Types of Motivation Essay -- essays papers

Types of Motivation Before we can examine different theories of achieving student need we must understand what it is. An article from ERIC (Educational Resources Information Center) pointed out an important distinction in types of motivation (1997) Student motivation naturally has to do with students desire to put down in the learning process. But it also concerns the reasons or goals that underlie their involvement or noninvolvement in academic activities. These two types of motivation are intrinsic and inessential motivation. If a learner is motivated intrinsically than they learn for the sake of learning. As opposed to an extrinsically motivated learner who will perform a trade union movement for external reasons such as good grades, prizes, etc. This difference is important to point out because different theories have different kinds of motivation as their lowest goal. One of the five theories that are going to be explored is problem-based learning. Problem Based Learn ing Often when sitting in any classroom either as a student or as a teacher one will invariably hear a student complain when will I ever use this in real life? This question occurs whenever a student is studying a subject that he/she did not choose for him/herself. Since mellowed schools today do not allow students to pick and choose their classes, this is a huge problem in American high schools. Peter Ommundsen (1999) thinks that this inability to affect the relevance of a subject to students lives in one the main obstacles in getting student motivation to increase. He presents the idea that to get students more knotty one must use problem-based learning. Problem-based learning (PBL) inspires students by involving them in meaningful activities rat... ...rstanding and Meaning by Students. (1994). North Central Regional Educational Laboratory. Retrieved April 20th from the wind vane http//www.ncrel.org/sdrs/areas/issues/content/cntareas/science/sc3learn.htmMacKinnon, M. (1999). CORE Elements of Student Motivation in Problem-Based Learning. In M. Theall (Ed.) Motivation from Within Approaches for Encouraging Faculty and Students to Excel (pp.49-58). San Francisco Jossey-Bass.McCombs, B., & Whisler, J.S. (1997). The Learner-Centered classroom and School. San Francisco Jossey-Bass.Nakamura, R. (2000). Healthy Classroom Management. Australia Wadsworth.Ommundsen, P. (1999). Problem-based Learning. In K. Ahmet & S. Fallows (Eds.), Inspiring Students Case Studies in Motivating the Learner (pp.25-32). London, NJ Kogan page.Reeves, D. (2002). The Daily Disciplines of Leadership. San Francisco Jossey-Bass.

landscapes essay :: essays research papers

Take-Home EssayThe world we live in today is always changing, whether it be technology or the land. As these changes happen upon place, society must adapt to them. umpteen an(prenominal) things begin to change as a result of this and society bes to turn into something completely different. unitary of the most overlooked changes that takes place is that of the purlieu and landscape. The landscape is one of the most important parts of our societys culture and has a great essence on how we live. It seems that straight off, many a(prenominal) individuals ar taking advantage of the land and zero appreciating it for every thing that it is worth. Its true that not everyone is going to look at the environment and landscape in the same way, however that is no excuse to disrespect it. Then again, a whole new argument tidy sum start from that, as different individuals argon going to have different views on what disrespecting the land. Many positive things have come in from taking advantage of the land, and also, there have been many prejudicial things to come as a result of this. It all depends on how you look at it. One thing is for sure though, no matter what the slickness is, the land and environment we live in plays a huge part in each of our everyday lives. Our landscape is constantly changing, since the Big Bang surmisal to present day. in that respect are many different factors which can a huge impact on the shaping of the land. There are many cancel disasters such as floods, typhoons, earthquakes, hurricanes, and even wildfires. They can change the face of the landscape and they can change the shape of the landscape. Then there is also the human factor. Many huge companies and businesses are always taking advantage, or as Denis Wood refers to as in The Spell of the Land, the raping of the land. It is a very rare sight to being driving nowadays and not see some display case of building being built or a future sight of some type of business. Ther e is nothing that can be done when looking at the natural disaster factor, but as for the human factor, there are move that people can do to prevent the raping of the land. Again, like I touched upon in the introduction, not all usage of the land by companies is a negative thing.landscapes essay essays research papers Take-Home EssayThe world we live in today is always changing, whether it be technology or the land. As these changes take place, society must adapt to them. Many things begin to change as a result of this and society beings to turn into something completely different. One of the most overlooked changes that takes place is that of the environment and landscape. The landscape is one of the most important parts of our societys culture and has a great effect on how we live. It seems that nowadays, many individuals are taking advantage of the land and nothing appreciating it for every thing that it is worth. Its true that not everyone is going to look at the environment and landscape in the same way, however that is no excuse to disrespect it. Then again, a whole new argument can start from that, as different individuals are going to have different views on what disrespecting the land. Many positive things have come from taking advantage of the land, and also, there have been many negative things to come as a result of this. It all depends on how you look at it. One thing is for sure though, no matter what the case is, the land and environment we live in plays a huge part in each of our everyday lives. Our landscape is constantly changing, since the Big Bang Theory to present day. There are many different factors which can a huge impact on the shaping of the land. There are many natural disasters such as floods, typhoons, earthquakes, hurricanes, and even wildfires. They can change the face of the landscape and they can change the shape of the landscape. Then there is also the human factor. Many huge companies and businesses are always taking adva ntage, or as Denis Wood refers to as in The Spell of the Land, the raping of the land. It is a very rare sight to being driving nowadays and not see some type of building being built or a future sight of some type of business. There is nothing that can be done when looking at the natural disaster factor, but as for the human factor, there are steps that people can do to prevent the raping of the land. Again, like I touched upon in the introduction, not all usage of the land by companies is a negative thing.

Ghost Stories :: English Literature

Ghost StoriesGhost stories revolve around lots of unquiet tales that work ondisplacing the readers fear. Some of the main techniques which makethem successful involve Fear, Drama, Danger and Suspense. However,the main idea is that they create stress too. Such stories which use tenseness to dramatic affect are The tearing Room by H.G. Wells andFarthing House by Susan Hill both are written in prototypical personnarrative to allow the reader to get scared along with the maincharacter. Both stories also build tension through their Style,Setting, Structure and Language.The Red Room is about a ghost hunter who is a known ghost,Farthing House is about a wo manhood who stays with her aunt at aresidential house and feels and sees a womans supernatural presencein her room - both tales have a dramatic twist at the end emphasis is created through The Red Rooms setting in many ways -Firstly I can assure you, said that it will take a real tangibleghost to frighten me. This dramatic opening t o the story sets theghost hunter as a Brave, Strong character. The word tangiblesuggests it will take more(prenominal) than a scary image to frighten him, yettension is caused because the reader now expects that something willbe frightening him - soon.H.G. Wells builds on this subtle tension and the supposed invincibleman by setting his story to contradict and unease the mansassurances, not only is he in a strange house with a legendary redroom (building immediate suspicion by the fact that the room isrenowned, You will show me to this haunted room of yours,) but Wellssurrounds him with grotesque characters too.The common chord custodians set the story by introducing the reader to theRed Room and through their crusty appearance. If is your ownchoosing, said the man with the withered arm and glanced at me squint-eyed only four lines into the story and the main character, alongwith the reader already senses that all is not well, mainly becausethe man is deformed - withered and becau se he is performing oddly i.e.looking askance. This action suggests the custodian knows somethingwe dont, he appears too shifty.Wells continues to build tension through introducing the second manwho also adds to the characterisation shambling step, more bent, morewrinkled, more aged, his lower lip half averted, hung pale and pinkfrom his decaying yellow teeth, began to cough. The verbshambling suggests the man may have a limp and the repetition of theword more portrays a disgusting image of the ageing wreck, barelyhuman. The mans manky description backs this up and encourages the

Opposing School Uniforms Essay -- essays research papers

School Uniforms In 1993, Will Rogers Middle School in Californias Long Beach County School District began discussing the idea of a civilise-wide uniform policy. That fall, Will Rogers became the first tutor in Long Beach County to have a mandatory uniform policy. Other schools in the district in short followed drawing national attention, including a personal visit from then President Clinton. Recent memories of school shootings around the nation caused President Clinton to urge other school districts to move to uniforms in his 1996 State of the Union Address. This started a seemingly endless debate over school uniforms in public schools. In order to be legal, every uniform policy has to have an pickax to not participate. Students that opt-out attend other schools that do not have uniform policies. Most Republicans and the more dull Democrats are in favor of uniforms while the more liberal Democrats oppose them. People in favor of uniforms support them for several reasons cited in a US Government manual on school uniforms decrease in violence and thefteven life threatening situationsamong students over designer clothing or expensive sneakers, prevention of gang members wearing gang colors and insignias at school, instilling students with discipline, service of process parents and students resist peer pressure to buy expensive clothing, helping students concentrate on their school work, and helping school officials to recognize intruders who come to the school. (Manual par. 2) People against uniforms oppose them for several reasons uniforms violate the first amendment right to granting immunity of expression, the claims of the supporters are not true, and problems in the schools are much bigger than a little ans... ...lace, I think a big part of the improvement in statistics was due to the implementation of uniforms. While a strict dress code, or uniforms, would probably improve the statistics, it is not the best option. I think the best option is a m andatory identification badge. Students would be required to wear a visible photo I.D. at all times when on campus. One school I visited had badges worn on a necklace. This policy has a few of the benefits of uniforms, like intruders being easily recognizable, but it does not impose on the student. This is a very realistic option. A great deal of employers require their employees to wear name badges while they are on the job (Nurses, Factory workers, etc.). Most employers do not specify a uniform to be worn. Uniforms are not the one-word answer to todays problems, but uniforms and/or ID badges could be used as part of the solution

Microraptor Gui: The Dinosaur with Four Wings :: Anthropology Essays Paleontology Papers

Microraptor Gui The Dinosaur with Four Wings Knowing that pterodactyls belong to a separate group of reptiles than dinosaurs, the thought of a dinosaur with wings may seem close towhat strange. But a fairly recent archeological find adds an extra detail to disembowel this idea truly bizarre a dinosaur with four wings. Microraptor gui, discovered by Xing Xu and colleagues, is believed to be a kind of missing link between strictly ground-dwelling dinosaurs and birds, that is to say Archaeopteryx, the earliest known creature to be considered a bird. While there can be no debate over the stripping itself, the implications made from its discovery havent been entirely accepted, with many arguing them altogether. Besides being an oddity, what makes this particular find so significant? What are these implications that have riled some scientists up, and what is it that these experts argue? Before any sort of discussion on the debate of what M. gui implies, however, the details of this odd reptiles discovered fossils should be given. by past research and findings, the leading theory on the origin of birds traces them back to dinosaurs, more specifically a type of bipedal dinosaur called theropods. Within this group of generally carnivorous dinosaurs are the dromaeosaurids, and they specifically are believed to be the closest dinosaur ancestors of birds. The discovered fossils of the dramaeosaurid M. gui form of a n earliest complete skeleton, and its been compared with a similar, antecedently discovered Microraptor skeleton. The place of M. guis discovery was Dapingfang, Chaoyang County in western Liaoning, China, also known as the Jiufotang Formation_. Xu and colleagues declare the fossils to be dated from the early cretaceous period (about 124 - 128 million old age ago_)_ through others radiometric dating and biostratagraphical correlations of that region_. Interestingly, the closest ancestors of many of the dinosaurs found within this area of China are believed to have lived not during the early Cretaceous, but the late Jurassic_. Paleogeographers have theorized that this area was thoroughly isolated during the very late Jurassic and into the early Cretaceous_. With paleontologists theorizing that Archaeopteryx came into existence 25 million years before the dated existence of these M. gui fossils_, M. gui is still believed to be a basal dromaeosaurid, meaning that its one of the earliest of this type of theropod, maintaining that these fossils are of an ancestor to Archaeopteryx and all birds.

Microraptor Gui: The Dinosaur with Four Wings :: Anthropology Essays Paleontology Papers

Microraptor Gui The Dinosaur with Four Wings Knowing that pterodactyls belong to a separate group of reptiles than dinosaurs, the thought of a dinosaur with wings may seem sensibly strange. But a fairly recent archeological find adds an extra detail to make this idea truly bizarre a dinosaur with four wings. Microraptor gui, ascertained by Xing Xu and colleagues, is believed to be a kind of missing link between strictly ground-dwelling dinosaurs and birds, namely Archaeopteryx, the earliest known creature to be considered a bird. small-arm there can be no debate over the discovery itself, the implications made from its discovery havent been entirely accepted, with many arguing them altogether. alike being an oddity, what makes this particular find so significant? What are these implications that have riled some scientists up, and what is it that these experts argue? Before any sort of discussion on the debate of what M. gui implies, however, the details of this o dd reptiles discovered fossils should be given. Through past research and findings, the leading theory on the rakehell of birds traces them back to dinosaurs, more specifically a type of bipedal dinosaur called theropods. Within this group of mostly carnivorous dinosaurs are the dromaeosaurids, and they specifically are believed to be the ambient dinosaur ancestors of birds. The discovered fossils of the dramaeosaurid M. gui form of a nearly complete skeleton, and its been compared with a similar, previously discovered Microraptor skeleton. The place of M. guis discovery was Dapingfang, Chaoyang County in western Liaoning, China, also known as the Jiufotang Formation_. Xu and colleagues declare the fossils to be dated from the early Cretaceous period (about 124 - 128 million years ago_)_ through others radiometric dating and biostratagraphical correlations of that region_. Interestingly, the close ancestors of many of the dinosaurs found within this area of China are b elieved to have lived not during the early Cretaceous, but the late Jurassic_. Paleogeographers have theorized that this area was thoroughly single out during the very late Jurassic and into the early Cretaceous_. With paleontologists theorizing that Archaeopteryx came into existence 25 million years before the dated existence of these M. gui fossils_, M. gui is put away believed to be a basal dromaeosaurid, meaning that its one of the earliest of this type of theropod, maintaining that these fossils are of an ancestor to Archaeopteryx and all birds.

Summary of Plato’s Apology

PLATOS APOLOGY In Platos plea, I found that it is only named Apology however there is nothing about apology there. It is mainly the defense of Socrates for his accusations. He was a very decent profound man. Socrates said I am not a clever speaker in any way at all-unless, indeed, by a clever speaker they mean almostone who speaks the truth. By this statement he was able to make people think that he is only telling the truth, not making false things with his intelligence. I am astound by the wisdom of Socrates. He was 70 years old when the prosecution happened.In that age he defended himself well and gave so practical logic in his speech that the accusers were just being dumb. Another thing that caught my attention is Socrates found the universal nature of human beings. every of us think that he is the roughly intelligent human in the world and no one can understand anything as he can. May be there are some people somewhere who are wiser than him but they are not around him. Socrates said, I am wiser than this man neither of us k this instants anything that is really worth knowing, but he thinks that he has knowledge when he has not, while I, having no knowledge, do not think I have.I seem, at any rate, to be a little wiser than he is on this point I do not think that I know what I do not know. With this speech he direct attacked the so called wise people of all time. Every human is same. God gave us all same talent. No one is more intelligent than the others. Who understand it, he become wiser. I found that the main reasons of accusing Socrates was not believe in the old gods and corrupting the youth of Athens. In those days, it was fantastic for anyone to go against the beliefs that were brought upon them. Meletus said that he is suing Socrates for voluntarily corrupting the young.Its stupid to sue someone just because they dont believe in your beliefs. All the major religions and scientific inventions of the world came by the different thinking. I f men didnt think different we would be live in the cave till now may be. I am inspired by Socrates wisdom and thought. Try to see things differently. Judge them in my own way. If they are wrong and I am right then I lead not care what other people think. I will loud my voice, give people logic and will definitely prove that I am right. MD ABDULLAH AL MASUD ID -02083047

Herzberg Theory Essay

Herzbergs Two Factor theory (Motivator-Hygiene) suggested that the factors involved in producing job happiness and motivation are separate and distinct from the factors that lead to job dissatisfaction. (Herzberg, 1987) In 1959, Frederick Herzberg found that people had 2 essential needs in life. 1. The humans need as an animal to avoid pain2. The humans need to grow psychologicallyAnd from the two founding, Herzberg has come up with a two factor theory or is also known as Motivator-Hygiene theory that has been a stepping stone for motivation in the workplace.Motivator-Hygiene TheoryHerzberg interviewed 203 engineers and accountants. A survey has been do to identify how they feel about their jobs. They were asked to remember back the clock time when they felt really good at their job and the feelings that associated during that time. And later, they were also asked to recall a time when they felt really bad towards the job and the feelings that associated with it. These results le d to two categories Job Satisfiers Job Dissatisfiers.* Motivator Factors (Job Satisfiers)Factors that create positive feelings. These included things such as achievement, responsibility, reaping in workplace and recognition. * Hygiene Factors (Job Dissatisfiers)Factors that are related to work context and environment. These includes company policy, administration, job security, salary and work conditions. The theory states that if the motivator factors are bring in in conjunction with hygiene factors then the job will be satisfying. If the hygiene factors are the only present factors, then the job will be in a neutral state.Employees are not dissatisfied and they have average performance. If the hygiene factors are not present then the job becomes dissatisfying, with or without motivators. Even though hygiene factors do not lead to extra work they are needed as building blocks to start productivity. Therefore, in monastic order move beyond this level, the motivator factors are ne eded.Herzberg, F.I. (1987), One more time How do you motivate employees? Harvard Business Review, Vol.65 (5), pp.109 120 Herzberg, F., Maunser, B. andSnyderman, B. (1959), The Motivation to Work, John Wiley and Sons Inc., New York, NY

Characteristics of Successful Online Learners

Although these atomic number 18 the main characteristics found in this article, I think there are much to a greater extent o the characteristics to online learners then meet the eye. (British Journal of Education Volvo 44 No 5 2013) In the article Exploring the link among entry characteristics, date behaviors, and course outcomes of online learners by Reran Housework and Ar digeste Top, talks about how the entry characteristics of early online learners were older, male, employed students, (THOMPSON 1 998) notwithstanding as online learning progressed all ages, sexes and employment office used online learning as the way they furthered education. Dabbing 2007) Participation behaviors of online learners were expound in the article as stack who possessed to a greater extent knowledge of online communication tools like blobs and interactive tools had increased knowledge of how online learning worked. The articled also stated that learners that had knowledge of CM tools tend to int eract more than other online learners. (Goodwin et al 2008) line of credit Outcomes have a large effect on online learners. An online leaner tends to return to learning and tell about the experience if they are satisfied with the outcome of their deliver the goodsments during their online experience.While I read this article thought about my own experience of wanting to learn online. I found I too possessed several of the characteristics described in the article. Although I found the article a bit one sided as to age, gender, and backgrounds, I did think that the article pointed out as online learning progresses the characteristics appear not to have the same in commons as it once did was a very good point to make showing that more and more people of all sexes, ages and backgrounds are turning to online learning just as they would face to face learning.Reading this article make me want to work harder on my degree. It made me want to study harder, to learn as much as I could so ca n show that online learning is not just for smart, male, employed people like it once was. That it is for all people who want to learn and achieve their goals. Anyone that wants to pursue an online education can do it they just have to want it. The conclusions in the article were accurate for the time it was written, it was objective to all online learners and was well written and articulated. The Scriptures teach us that anyone can learn and be taught.Proverbs 226 produce up a child in the way he should go even when he is old he will not depart from it. Characteristics of online learners are similar to everyone in some aspect of life. I have learned that everyone makes their own path, their own goals, and achievements. Reading this article on the topic of characteristics of online learners showed me how I can be a better online student, ask for more out of my time as an online learner, and want more as an online learner. Want to strive to learn more, add more, and ask more quest ions in my online learning and in my everyday life.I will make my online learning experience the best it can be. I will achieve my goal of earning a degree and I will make a better life for me and my family. Reading this article has given me more passion and more drive that I can earn this degree and I can have my cake and eat it too. Characteristics of online learners may be similar to most online learners, but have learned that even though entry characteristics, participation behaviors, and course outcomes may have an effect on online learning outcomes, as individuals we learn other than and want different things out of our online earning experiences.Online learning is unique experience and it takes planning, organization, and dedication to be an online learner, we can all do it and we can all achieve our goals if we pose our minds to it. In our life as children we have really always been online learners, just not on the internet. We learned from the lines in the Bible, we learne d from the line in our domesticate books, and we have learned from our parents. If you apply all that you have learned in your life to your online learning you will be a Successful Online Learner.

Bilingual Education and the Cycle of Native Language

The original objective of bilingualist commandment was to ensure students would not fall behind academically because of a poor command of English and to stepwise teach them English as a second manner of speaking. If language-minority students were taught some subjects in their native tongue, proponents insisted, they potentially could learn English without sacrificing content knowledge.But bilingual precepts critics argue that the approach keeps students in a cycle of native language dependency that ultimately inhibits significant progress in English language acquisition. Proponents counter that if students first learn to read in the language they are fluent in and then transfer the skills over to English-their second language-they will organize stronger literacy skills in the long term. Plus, they argue that in an increasingly global society, schools, far from discouraging native-language retention, should work to help students maintain their native tongues, even as they in an y case teach them English.Complicating the debate is the range of programs that, by some peoples definition, fall under the umbrella of bilingual fosterage. Some use bilingual education to refer only to transitional bilingual education or two-way bilingual programs while others consider any program designed for students with limited increase in English to be bilingual. For instance, they may refer to English-as-a-second-language programs, where students are typically taught solely in English, as bilingual education.Public sentiment against transitional bilingual education has been growing. On June 2, 1998, calcium voters overwhelmingly approved Proposition 227, an opening night that largely eliminated bilingual education from the states public schools. Under the California initiative, most LEP students in that state are now placed in English-immersion programs.Arizona voters followed suit by passing Proposition 203, a measure correspondent to the California initiative, on Nov. 7 , 2000. While the California initiative reduced the percentage of LEP children in bilingual education from 29 percent to 12 percent, the Arizona initiative is expected to end bilingual education because, unlike the California initiative, it makes it very difficult for parents to seek waivers from English immersion that would permit some bilingual education to continue. Arizona officials expect to implement the law by fall 2001.Despite the English only message that Propositions 227 and 203 bear, the debate over how best to instruct lingually diverse students is far from decided nationwide.

It Infrastructure Security Policy

social unit 6 ASSIGMENT 1 IT radix Security Policy Purpose of the meshing InfrastructureThe Companies values openness and promotes admission fee to a wide range of teaching accordingly, the campus info systems have been designed to be as open as possible.The Companies meshing consists of teaching cables and jacks from the wire clo associations to the expendrs work station, or wireless access points to a workrs PC copper and optical data communications cables Ethernet switches, routers, bonifaces, and peripherals systems to enable and manage access and systems to monitor the talent and maintain the uprightness of the communicate, with the goal to provide high-pitched availability and capacity to support the needs of the network users. The reliability, availability and adequate capacity of network resources is unfavourable to the day-to-day function of the Companies.Each member of the Companies community (students, faculty, staff, and guests) is anticipate to protect the equity of the network and to know and adhere to Companies rules, regulations and guidelines for their attach use. Regulations that govern personal conduct and use of Companies facilities also founder to the use of network resources. * Components of the Network Infrastructure Policy * Appropriate physical exertion * Unacceptable Use * Access Restrictions * Request for Evaluation sym courseize thisChapter 2 Why Security is NeededComponents of the Network Infrastructure Policy * * Connecting Devices to the Network * The campus network is a shargond resource. It is therefore necessary to strike a remnant between enabling opportunities for teaching and research, and protecting the integrity of network resources. To this end, Companies must be involved in the planning, acquisition, maintenance, and on-going plug inivity of all(a) network devices. This result ensure the distinguish network design, interoperability of components and integrity of operation.If a device is commit ted to the network infrastructure without prior consultation, Companies bunsnot guarantee the on-going connectivity and proper operation of the device. * * Wireless Network Equipment The interest and use of wireless networking (802. 11a, 802. 11b & 802. 11g, Wi-Fi) is evolving rapidly. All network use policies apply to the use of wireless LAN technology. Wireless access to Companies resources which pass on be secured through a of import aut hentication system, except for particular(prenominal) departmental needs.The participation pull up stakes work with individual departments and colleges to help address their special needs for wireless technology. * * Domain seduce Service profit servers for academic departments or administrative units serving campus related reading whitethorn need DNS entries set up for the server. Requests for DNS entries will need to be submitted to the Networking unit of Companies for approval. No otherwise DNS server should be setup by other campus u nits. DNS names will not be given to a server set up for personal use, much(prenominal) as a personal network server.Any web site served on the web servers maintained by Companies such as www. uww. edu, facstaff. uww. edu, and students. uww. edu will carry the appropriate path names as URL no DNS name will be given. Occasionally members of the Companies community may sponsor an organization that is loosely affiliated with the Companies. These organizations may be of professional, scholarly, partnership or entrepreneurial nature. Under certain circumstances it may be appropriate for these organizations to hold DNS names other than uww. edu , while innkeepering them in the Companies domain.Provided that the use of these domains support the Companiess mission and are consistent with all applicable Companies policy, Companies may host them within the uww. edu domain. Approval and regular review of these domains will be conducted on a case-by-case basis by the Chancellor and the CIO. Additionally, there are proficient criteria that must be met, such as 1. Servers in the domain must reside in the McGraw data center. 2. This progress must be listed as the proficient contact with the registrar**, so that others are advised of whatsoever changes and can respond appropriately. 3.Only UW-W DNS servers should be specified to the registrar * * Dynamic Host Control communications protocol The DHCP service delivers IP information to campus workstations to provide Internet connectivity. The central DHCP service and the management of IP assignments is administered by Companies. No other DHCP service should be set up on campus without prior consultation with Companies, and all to meet specific administrative or academic needs. * hostile Access to Network Resources While web access is sufficient for the majority of Companies educational and course activities there are some instances when direct access to network resources is necessary.To enable remote access to network resources in a secure manner that protects confidentiality and integrity of Companies and personal information Virtual Private Networking is a method by which a user can access UWWs internal network via the profits in a secure manner through a firewall or similar trade protection layer. Remote access for some campus services, such as e-mail and library databases, may be addressed in separate campus policies. Authorized users must only connect to the Companies network from information processing systems that conform to the Network Infrastructure Use Policy security requirements.This includes ensuring that computers are fully patched with the latest operating system updates and have reliable antivirus software. Appropriate UseListed below are the policies that govern data network access and usage for students, staff and faculty at the Companies of Wisconsin Whitewater. 1. Authorized users Authorized users are (1) menstruum faculty, staff, and students of the Companies (2) indivi duals connecting to a public information service support on the Campus network and (3) others who are specifically authorized to use a particular computing or network resource by the campus unit accountable for the resource. . General Guidelines Those who use the campus network resources are expected to do so responsibly, that is, to comply with state and federal fairnesss, with this and other policies and procedures of the Companies, and with normal standards of professional and personal adroitness and conduct. 3. Security Information security at Companiesis everyones responsibility. To maintain security in using the campus network services, it is grievous to adhere to the following guidelines * Protect your login ID and password.Computer nibs, passwords, ids and other types of ascendance are assigned to individual users and should not be shared with others. * Be aware that the person to whom an account is assigned will be held accountable for any activity originating from t hat account. * Do not access data or systems for which you have not been given specific authority. * Take reasonable steps to ensure that your background knowledge or laptop computer system does not create a security risk when committed to the network, including keeping anti-virus software and operating patches up-to-date. Report security violations. 4. Confidentiality Information stored on computers is considered confidential, whether protected by the computer system or not, unless the owner intentionally makes that information available to other groups or individuals. The Companies of Wisconsin Whitewater takes the position that computer users desire that the information that they store on central and/or campus shared computing resources remain confidential.While all efforts will be made to ensure confidentiality, users should be aware that data (including e-mail) might, due to software or hardware failure, become accessible to those Companies who are not authorized for that acce ss. Companies personnel may also on occasion have access to such data while perform routine operations or pursuing apparent systems or user problems. No guarantee of complete privacy is made or implied by this policy. Requests for the disclosure of confidential information will be governed by the provisions of the Family Educational Rights and silence Act of 1974 (FERPA) and the Wisconsin Open Records Statutes .All such requests will be honored only when approved by Companies officials who are the legal custodians of the information requested, or when required by state or federal law, or court order. Users found to be copying, modifying, or otherwise accessing information for which they have not been granted permission may be liable to disciplinary action. Unacceptable UseNetwork resources at this Companies may not be used for flagitious activities, commercial purposes not associated with the Companies, or uses that violate other Companies policies or guidelines.The following act ivities are NOT acceptable use of the campus network resources * Damaging or performing unlicenced removal of networking equipment, software or data * Tampering with network hardware, wiring, or software * Disrupting or interfering with the normal operation of network communications, generating profligate network activity or performing unauthorized monitoring of network traffic * Willfully introducing computer viruses or other disruptive programs into the Companies network, which are think to damage or create excessive laden on network resources * Intentionally violating or attempting to bypass network security strategies * Using unauthorized accounts, passwords, IP addresses or other network access information * Accessing or modifying any software, files, data or other Companies information for which an individual has not been given license * Using network resources to harass or keep others * Using network resources to impersonate others or to forge anothers identity * Interf ering with the computing activities of others. * Setting up network services or equipment without knowledge or involvement of Companies. * Violating state, federal or copyright laws * Using network resources for commercial activity or pecuniary gain which does not conform to UW-W rules and regulations Access RestrictionsAccess to campus network resources may be wholly or partially restricted by the Companies without prior notice and without the go for of the user when 1. required by and consistent with law 2. when there is reason to believe that violations of policy or law have taken place 3. hen the continued access/use of network resources by an individual significantly affects the integrity, performance, or security of the campus network as a whole The individual will be notified of the reason and duration of the access prohibition as soon as possible. Access will be restored when the situation has been resolved. These are general Companies policies departments or other units may place additional restrictions on the resources that they manage. Work cited http//www. uww. edu/icit/governance/policies/network/infrastructure. htmlg3ctoolkit. net/ /IT_Infrastructure_Security_ United Kingdom www. wokingham. gov. uk/EasysiteWeb/getresource. axd?It Infrastructure Security PolicyUNIT 6 ASSIGMENT 1 IT Infrastructure Security Policy Purpose of the Network InfrastructureThe Companies values openness and promotes access to a wide range of information accordingly, the campus information systems have been designed to be as open as possible.The Companies network consists of data cables and jacks from the wiring closets to the users work station, or wireless access points to a users PC copper and optical data communications cables Ethernet switches, routers, servers, and peripherals systems to enable and manage access and systems to monitor the capacity and maintain the integrity of the network, with the goal to provide high availability and capacity to support the nee ds of the network users. The reliability, availability and adequate capacity of network resources is critical to the day-to-day function of the Companies.Each member of the Companies community (students, faculty, staff, and guests) is expected to protect the integrity of the network and to know and adhere to Companies rules, regulations and guidelines for their appropriate use. Regulations that govern personal conduct and use of Companies facilities also apply to the use of network resources. * Components of the Network Infrastructure Policy * Appropriate Use * Unacceptable Use * Access Restrictions * Request for EvaluationRead thisChapter 2 Why Security is NeededComponents of the Network Infrastructure Policy * * Connecting Devices to the Network * The campus network is a shared resource. It is therefore necessary to strike a balance between enabling opportunities for teaching and research, and protecting the integrity of network resources. To this end, Companies must be involved in the planning, acquisition, maintenance, and on-going connectivity of all network devices. This will ensure the appropriate network design, interoperability of components and integrity of operation.If a device is connected to the network infrastructure without prior consultation, Companies cannot guarantee the on-going connectivity and proper operation of the device. * * Wireless Network Equipment The interest and use of wireless networking (802. 11a, 802. 11b & 802. 11g, Wi-Fi) is evolving rapidly. All network use policies apply to the use of wireless LAN technology. Wireless access to Companies resources which will be secured through a central authentication system, except for specific departmental needs.The company will work with individual departments and colleges to help address their special needs for wireless technology. * * Domain Name Service Internet servers for academic departments or administrative units serving campus related information may need DNS entries set up fo r the server. Requests for DNS entries will need to be submitted to the Networking unit of Companies for approval. No other DNS server should be setup by other campus units. DNS names will not be given to a server set up for personal use, such as a personal web server.Any web site served on the web servers maintained by Companies such as www. uww. edu, facstaff. uww. edu, and students. uww. edu will carry the appropriate path names as URL no DNS name will be given. Occasionally members of the Companies community may sponsor an organization that is loosely affiliated with the Companies. These organizations may be of professional, scholarly, partnership or entrepreneurial nature. Under certain circumstances it may be appropriate for these organizations to hold DNS names other than uww. edu , while hosting them in the Companies domain.Provided that the use of these domains support the Companiess mission and are consistent with all applicable Companies policy, Companies may host them wi thin the uww. edu domain. Approval and regular review of these domains will be conducted on a case-by-case basis by the Chancellor and the CIO. Additionally, there are technical criteria that must be met, such as 1. Servers in the domain must reside in the McGraw data center. 2. This progress must be listed as the technical contact with the registrar**, so that others are aware of any changes and can respond appropriately. 3.Only UW-W DNS servers should be specified to the registrar * * Dynamic Host Control Protocol The DHCP service delivers IP information to campus workstations to provide Internet connectivity. The central DHCP service and the management of IP assignments is administered by Companies. No other DHCP service should be set up on campus without prior consultation with Companies, and only to meet specific administrative or academic needs. *Remote Access to Network Resources While web access is sufficient for the majority of Companies educational and business activities there are some instances when direct access to network resources is necessary.To enable remote access to network resources in a secure manner that protects confidentiality and integrity of Companies and personal information Virtual Private Networking is a method by which a user can access UWWs internal network via the internet in a secure manner through a firewall or similar security layer. Remote access for some campus services, such as email and library databases, may be addressed in separate campus policies. Authorized users must only connect to the Companies network from computers that conform to the Network Infrastructure Use Policy security requirements.This includes ensuring that computers are fully patched with the latest operating system updates and have current antivirus software. Appropriate UseListed below are the policies that govern data network access and usage for students, staff and faculty at the Companies of Wisconsin Whitewater. 1. Authorized users Authorized use rs are (1) current faculty, staff, and students of the Companies (2) individuals connecting to a public information service supported on the Campus network and (3) others who are specifically authorized to use a particular computing or network resource by the campus unit responsible for the resource. . General Guidelines Those who use the campus network resources are expected to do so responsibly, that is, to comply with state and federal laws, with this and other policies and procedures of the Companies, and with normal standards of professional and personal courtesy and conduct. 3. Security Information security at Companiesis everyones responsibility. To maintain security in using the campus network services, it is important to adhere to the following guidelines * Protect your login ID and password.Computer accounts, passwords, ids and other types of authorization are assigned to individual users and should not be shared with others. * Be aware that the person to whom an account i s assigned will be held accountable for any activity originating from that account. * Do not access data or systems for which you have not been given specific authority. * Take reasonable steps to ensure that your desktop or laptop computer system does not create a security risk when connected to the network, including keeping anti-virus software and operating patches up-to-date. Report security violations. 4. Confidentiality Information stored on computers is considered confidential, whether protected by the computer system or not, unless the owner intentionally makes that information available to other groups or individuals. The Companies of Wisconsin Whitewater takes the position that computer users desire that the information that they store on central and/or campus shared computing resources remain confidential.While all efforts will be made to ensure confidentiality, users should be aware that data (including e-mail) might, due to software or hardware failure, become accessibl e to those Companies who are not authorized for that access. Companies personnel may also on occasion have access to such data while performing routine operations or pursuing apparent systems or user problems. No guarantee of complete privacy is made or implied by this policy. Requests for the disclosure of confidential information will be governed by the provisions of the Family Educational Rights and Privacy Act of 1974 (FERPA) and the Wisconsin Open Records Statutes .All such requests will be honored only when approved by Companies officials who are the legal custodians of the information requested, or when required by state or federal law, or court order. Users found to be copying, modifying, or otherwise accessing information for which they have not been granted permission may be liable to disciplinary action. Unacceptable UseNetwork resources at this Companies may not be used for unlawful activities, commercial purposes not associated with the Companies, or uses that violate o ther Companies policies or guidelines.The following activities are NOT acceptable use of the campus network resources * Damaging or performing unauthorized removal of networking equipment, software or data * Tampering with network hardware, wiring, or software * Disrupting or interfering with the normal operation of network communications, generating excessive network activity or performing unauthorized monitoring of network traffic * Willfully introducing computer viruses or other disruptive programs into the Companies network, which are intended to damage or create excessive load on network resources * Intentionally violating or attempting to bypass network security strategies * Using unauthorized accounts, passwords, IP addresses or other network access information * Accessing or modifying any software, files, data or other Companies information for which an individual has not been given authorization * Using network resources to harass or intimidate others * Using network resour ces to impersonate others or to forge anothers identity * Interfering with the computing activities of others. * Setting up network services or equipment without knowledge or involvement of Companies. * Violating state, federal or copyright laws * Using network resources for commercial activity or financial gain which does not conform to UW-W rules and regulations Access RestrictionsAccess to campus network resources may be wholly or partially restricted by the Companies without prior notice and without the consent of the user when 1. required by and consistent with law 2. when there is reason to believe that violations of policy or law have taken place 3. hen the continued access/use of network resources by an individual significantly affects the integrity, performance, or security of the campus network as a whole The individual will be notified of the reason and duration of the access restriction as soon as possible. Access will be restored when the situation has been resolved. Th ese are general Companies policies departments or other units may place additional restrictions on the resources that they manage. Work cited http//www. uww. edu/icit/governance/policies/network/infrastructure. htmlg3ctoolkit. net/ /IT_Infrastructure_Security_ United Kingdom www. wokingham. gov. uk/EasysiteWeb/getresource. axd?

English Literature: Frankenstein Essay Essay

Frankenstein was written by Mary Shelley when she was only eighteen days old after a nightmare she had. It was first published on 1st January 1818 and was an instant success. Using the style of the Gothic Novel, Frankenstein was the first science-fiction phonograph recording ever written. Almost two centuries later it has become not only a widely read classic, but also one of the most authoritative novels ever written. Frankenstein is a moral tale that deals with issues and ethics of medical and scientific advancement and how far humans should go in tampering with nature.The story raises questions as to who should have final power over life and human nature, God or humans. Shelley calls her book a Modern Prometheus, beca office there are many similarities in the plots. The Greek God, Prometheus, gave the human race fire, out of pity so they could eat, but also brought them danger, and was punished for it by Zeus. Prometheus was a hero to humans, but Dr. Victor Frankenstein is a v illain because he did nothing to contribute to the world he did everything for himself rather than using his knowledge for the good of others.Shelley does not express her views, but simply tells a story. The story explores the dire consequences of meddling in such serious matters. In a dramatic and shocking way she is more persuasive and challenging to citizenry than if she had directly preached her views. Without directly telling people what they ought to think, she is powerfully able to make people question the morality of their actions in a day of rapid scientific advances. The Gothic Novel was a very popular style of writing in the late eighteenth to mid-nineteenth century.Shelley used this style because she knew it would appeal to the masses. Its use of horror, delirium and the supernatural was exciting, intriguing and macabre. Although at one level it was frightening, it was also intriguing and compelling. Although on the surface it repelled, at a deeper level a reader was bony to the horror, just as the curious are drawn to view victims of an accident. Her clever use of horror disguises her Puritanical views by letting the dire outcome of an preoccupy doctor who creates a monster speak for itself. Victor Frankenstein Dr.Victor Frankenstein is the main protagonist of the novel and is a complex character. The bulk of the story is told from his point of view, disclosure his struggle to deal with the responsibility for the tragic consequences of his playing God by creating a monster from dead bodies he stole from graves. Frankenstein is a very futile and conceited man. He believes totally in his own ability and power. He is self-centred, but at the same time lacks self-awareness. I doubted not that I should ultimately succeed. p. 42 Frankensteins ego is so immense that he comes to see himself as God-like.His dream to create a physically superior race that allow worship him as its God is the dream of a megalomaniac. He has delusions of grandeur alm ost to the point of considering himself as the Saviour of the world. Although Dr. Frankenstein admits that he was at first shy(p) about whether he should perform the act of human mental home this hesitancy is quickly taken over by his arrogance and desire to succeed. He thinks he can do no wrong. I doubted at first but my imagination was too much exalted to permit me to doubt of my ability p. 42Frankenstein in one sense is an idealist in that he wanted to create a perfect race, a better race than current, imperfect humanity. He has a vision of an army of physically superior humans with high intelligence. However the reality of his method is to combine a collection of different consistency parts from different human beings, with different proportions, from graves and vaults. His ideal is very different to reality, showing how out of touch with reality he really is. It also shows his immorality, for he disregards authority and has a lack of respect for the dead.Frankensteins readi ness to mutilate and steal bodies shows that he thinks of the deceased bodies as merely physical carcasses for use at his disposal. He seems to have no morals or ethics at all and doesnt even think about the consequences if he was caught. I collected bones from charnel-houses and disturbed, with profane fingers, the tremendous secrets of the human frame. p. 43 Frankensteins obsession with creation drives him to break down the boundaries of life and death. He is oblivious to the out-of-door world and nothing else matters to him. Still urged on by an eagerness which perpetually increased, I brought my work near to a conclusion. p. 43 But once creating his being, when the whale awakes, Frankenstein is terrified by it, and runs away. His ideal of a perfect, flawless being is crushed at the sight of his hideous creation. Frankenstein instantly rejects the Monster, fleeing from its outstretched arms. He is judgemental and shallow, judging his creation on looks, not personality. Howeve r, scientists are supposed to be objective instead of subjective. Now I had finished, the beauty of the dream vanished P.

The Big Three in Economics: Adam Smith, Karl Marx, and John Maynard Keynes Essay

EconomicsIntroduction Adam Smith and Karl Marx are some of the few economists whose school of thoughts impacted the worlds frugality through different generations. Smith argued that when individuals of a society wager in self-interest, they collectively afford to acquire services and goods the society requires. This mechanism is famously cognise as the invisible hand, in Adams book The Wealth of Nations. Contrast with Adams theory, Karl Marx believes that a capitalist will take good of his labor forces for his own self-interest, and therefore it is better for individuals to be community oriented(Jingham & Girija, 2014). According to Smith, economic turning point is the situation where there is a drop in the economy. need of employment is one of the indicators of a recession situation. Therefore, if each individual takes the initiative to generate income for self-interest, they will end up collectively averting an economic recession period. According to Karl Marx, greed and self-interest are not good for business organizationes and they are hazards in the society. Greed in business can occur when the rich business owners take advantage of their employees for their own self-interest and growth(Skousen, 2012). This amplifies the gap between the poor and the rich. However. Greed and self-interest can also be beneficial to any presumption business and society. Adam Smiths school of thought contradicts with the moral values and ethics on greed andself-interest(Jingham & Girija, 2014). Greed will make individuals work extra hard in their distinct fields and, in the long run, these individual self-motivated interests add up to the aggregate well-being of the business. An example is an accountant, a procurance manager, the marketer, and the administrator, all working with self-interest will eventually jointly contribute greatly to the success of the business and the society. According to my current group, it is ethical for each penis t o work jointly with the rest of the members to achieve the groups set objectives. Greed and self-interest are considered unethical for the group because it may lead to the fade away of the group. This ethical perspective resemblesKarl Marx theory, since the aim of the group is to join us together for better achievement of our goals.ReferencesJingham, M., & Girija, M. (2014). History of Economic Thought(Adam Smith and Karl Marx Contributions). New York Vrinda Publications P Ltd.Skousen, M. (2012). The giant Three in Economics Adam Smith, Karl Marx, and John Maynard Keynes. Routledge Publishers Chicago.Source document

Accounting Theory and Practice Essay

interrogate 1 inquire 1.8What is the disagreement between developing a theory by induction and developing a theory by deduction? heading 2 head teacher 1.9Is the call for of fiscal method of bill theory a bluster of time for score students? let off your answer. caput 3 interrogative mood 1.26Would you reject as insignificant and trivial a positive theory of accounting on the basis that in a erupticular seek study the results derived failed to support the hypotheses and the related theory? explicate your answer.QUESTION 4 unbelief 1.27 (NEW)The International report Standards Board has a number of roles, including formulating accounting standards and developing a conceptual fabric. Is the work they do in developing an accounting standard or the conceptual framework normative or positive in nature?QUESTION 5 interview 1.33 (NEW)In this chapter we provided quotes from Gray, Owen and Adams (2010), in which they discuss an app bent herding phenomenon that seems to b e occurring in respect of the selection and put on of particular theories. They state, there has been a strange herding tendency, especially round authenticity theory, as substantially as stating that they also have a sneaking feeling that institutional theory may be coming up fast as the next theory around which to herd.What do they mean by this app bent practice of herding, and what ar some possible advantages and disadvantages that atomic number 18 related to this practice?QUESTION 6 doubt 1.35 (NEW)Do we really need financial accounting theory if all we are pertained in doing is developing accounting standards?tutorial 2 Semester 2 2014Deegan affairs 2 and 3The financial describe environment and Regulation of financial accountingQUESTION 1 Question 2.3Do you believe that the media portray accounting numbers, such as profits, as some elucidate of hard and objective performance indicator? wherefore do you think they might do this, and, if they do, what are some of th e implications that might arise as a result of this approach?QUESTION 2 Question 2.7Is it appropriate to look at changes or trends in corporate profits over time without reservation any adjustments? Explain your answer.QUESTION 3 Question 2.14If regulators acted in accordance with predictions provided by the private interest theory of rule, which assumes that all individuals (including politicians and regulators) are motivated by their own economic self-interest, what is the likelihood of the introduction of regulations aimed at reducing the problems associated with climate change particularly if business corporations opposed such regulations?QUESTION 4 Question 3.7Is regulation to a greater extent likely to be required in respect of public goods than other goods? Why?QUESTION 5 Question 3.30Accounting headline 3.9 (SEE END OF TUTORIAL 2 QUESTIONS) discusses how European banks were fitting to lobby the European Union (EU) so as to be regulated by a water down version of the accounting standard IAS 39. Explain whether the decision of the EU to embrace a wet down version of the standard is consonant with a public interest theory of regulation sentiment, or whether it can be explained by an alternative theoretical sentiment (which you should attempt to identify).QUESTION 6 Question 3.35Let us assume that the government has become concerned that existing disclosure regulation tends to fixate on the financial performance of organisations moreover fails to address other aspects of corporate performance, including a ruin to provide culture almost corporate social and environmental impacts as well as close various initiatives and investments an organisation has undertaken to improve its social and environmental performance. As such, the government has decided to introduce polity that provide require business corporations to provide development about the social and environmental impacts of their operations, as well as the social and environmental initiatives undertaken by the corporations.You are required to do the future(a) (a) Explain from a public interest theory perspective the rationale for the government introducing the legislation and how the government will at last assess whether any proposed legislation should actually be introduced. (b) forebode from a capture theory perspective the types of constituents that will benefit in the long run from any social and environmental disclosure legislation. (c) Predict from an economic interest group theory perspective whether any potential legislation to be introduced will lead to an increase in the accountability of corporations in relation to their social and environmental performance despite any implications that this increased corporate accountability might have for the financial success of large but heavily polluting organisations.TUTORIAL 3 Semester 2 2014Deegan Topics 4 and 5International accounting and The conceptual framework projectQUESTION 1 Question 4.19It i s often argued that the accounting standards of the FASB are rule-based, whereas the accounting standards issued by the IASB are principles-based. Rules-based standards by their nature can be quite complex, particularly if they seek to cover as many another(prenominal) situations as possible. Do you think it would be easier to circumvent the requirements of rules-based or principles-based accounting standards?QUESTION 2 Question 4.22Does the calibration of accounting standards on a global basis necessarily equate with a standardisation in accounting practice?QUESTION 3 Question 4.25In considering the relevance of IFRS to developing countries, Chand and washcloth (2007, p.606) state (see below). Explain the reasons behind Chand and Whites claim. While the forces of globalization and convergence are paltry accounting practices towards a unified, or at least, harmonized regulatory framework for financial reporting, this is unlikely to best(p) serve the diverse interests of dispa rate user groups of financial reports.QUESTION 4 Question 4.27Ball (2006, p. 17) makes the following comment (below). Explain the basis of Balls comments. In sum, even a cursory suss out of the political and economic diversity among, IFRS-adopting nations, and of their past and present financial reporting practices, makes the notion that uniform standards alone will produce uniform financial reporting seem nave.QUESTION 5 Question 4.30 (NEW)In continental European countries, prior to the adoption of IFRS, the domestic accounting rules were typically much more aligned with local taxation regulation than would be the end in countries like the unite States, the United Kingdom, Canada, Australia or New Zealand. Why do you think this could have been the case?QUESTION 6 Topic 5 Question 6.7Conceptual framework projects identify a number of qualitative criteria that financial information should possess if it is to be useful for economic decision making. Two such attributes are neutr ality and eidetic confiningness? Do you believe that financial information can, in reality be neutral and representationally faithful? Explain your answer.QUESTION 7 Topic 5 Question 6.10The two main qualitative characteristics that financial information should possess have been identified as relevance and reliability. Is one more important than the other, or are they equally important? TUTORIAL 4 Semester 2 2014Deegan Topic 6Chapter 10 Reactions of large(p) markets to financial reportingQUESTION 1 Question 10.4 (NEW)What is an event study and why would an event study be of relevance to an accounting standard-setter?QUESTION 2 Question 10.9 (NEW)If individuals have access to insider information and are able to make large gains on a securities market as a result of apply information that is not widely known, then is this an indication that the market is inefficient?QUESTION 3 Question 10.16 (NEW)Evidence shows that share damages might not fully react to financial accountin g information promptly and that abnormal returns might persist for a period of time following the release of information (a case of post-announcement drift). Does this indicate that securities markets are not efficient and that assumptions about market efficiency should be jilted?QUESTION 4 Question 10.17If an organisations operations rely heavily on the specialized expertise of its management team, would you expect there to be a higher or a imposecorrespondence between the net assets recognised in the statement of financial position (balance sheet), and the total market value of the organisations securities, relative to an organisation that relies more on tangible assets (for example, commonly employ plant and machinery) to generate its income?QUESTION 5 Question 10.24Refer to Accounting Headline 10.3 (SEE END OF TUTORIAL 4 QUESTIONS) and explain why investors might have reacted to the false rumour. Is the reaction of investors to this false rumour consistent with the view t hat the capital market is efficient or inefficient?QUESTION 6 Question 10.25 critique Accounting Headline 10.7 (SEE END OF TUTORIAL 4 QUESTIONS) and explain the reason for the change in the price of Wesfarmers shares. Also, what might have caused the price changes in the shares in the other retail organisations?QUESTION 7 Question 10.28Read Accounting Headline 10.10 (SEE END OF TUTORIAL 4 QUESTIONS) and, relying on some of the capital markets studies considered in this chapter, explain why the share prices of the pharmaceutical companies might have reacted in the way they did.TUTORIAL 5 Semester 2 2014Deegan Topics 8 and 9 Accounting for Corporate Social ResponsibilitiesQUESTION 1 Question 8.1Explain the notion of a social contract, and what relevance the social contract has with respect to the legitimacy of an organisation.QUESTION 2 Question 8.7If an organization was involved in a major accident or incident, would you expect it to use vehicles such as an annual report or a s ustainabilityreport to try to explain the incident? If so, explain how and why it would use reports in this way.QUESTION 3 Question 8.21 (NEW)Chapter 8 divided Stakeholder speculation into the ethical branch and the managerial branch. Explain the differences between the two branches in terms of the alternative perspectives about when information will, or should, be provided by an organisation.QUESTION 4 Question 9.1What has the environment got to do with accounting (NEW)?QUESTION 5 Question 9.9What is an externality, and why do financial accounting practices typically ignoreQUESTION 6 Question 9.20 (NEW)Explain what is meant by the following statementIn the long term, environmental sustainability is necessity for both social and economic sustainability, so attention to minimising impacts in respect of the environment is necessary to go through a sustainable social and economic future.QUESTION 7 Question 9.35 (NEW)What is a cap-and-trade system and what accounting issues does it create?QUESTION 8What is international integrated reporting and how does it differ from the current financial reporting system we have. TUTORIAL 6 Semester 2 2014Topic 7 positively charged accounting theoryQUESTION 1 Question 7.5Explain why a decision made in London by members of the InternationalAccounting Standards Board and incorporated within an accounting standard could influence the business operate strategies employed by a manager in Melbourne, Australia.QUESTION 2 Question 7.10As part of efforts to develop a revised Conceptual Framework for Financial Reporting, the IASB is currently investigating alternative approaches for cadence the assets and liabilities of reporting entities. In relation to asset measurement it appears that fair value is a favoured option of the IASB. In this regard, would researchers who embrace the view that accounting plays a vital role in reducing the contracting be of an organisation favour the adoption of fair value in all situations? Ca refully explain your answer.QUESTION 3 Question 7.12Would managers who have negotiated debt contracts with accounting-based covenants based around rolling GAAP be relatively more likely to lobby an accounting standard-setter about a proposed accounting standard than would a manager from a firm who has negotiated accounting-based debt covenants that use frozen GAAP. Why or why not? Illustrate development AASB2 Share Based Payments and assume that it is the year 2003.QUESTION 4 Question 7.15Do you think the polity decisions made by members of the International Accounting Standards Board would or should give consideration to the insights provided by Positive Accounting Theory? Why?QUESTION 5 Question 7.17If senior managers within a friendship were rewarded by way of accounting-based bonus plans then would they, or the owners/shareholders (or both), prefer the use of conservative accounting methods? Explain the reasoning for your answer.QUESTION 6 Question 10.22Accepted assumptio ns about market efficiency mean that it is the informationcontent of disclosure, and not the form of the disclosure, that is valued by the market. Therefore it should not matter whether information is disclose within the notes to the financial statements, or in the financial statements themselves. If this is true, then why would managers care if something such as a lease liability is disclose only in the notes, or included within the liabilities disclosed within the balance sheet?

Of Mice and Men Essay Essay

The language of friendship is not in words, but in meanings Henry David ThoreauWhile reading the refreshed, Of Mice and Men, the reader gets a front row earn into the relationship of the both main characters, Lennie and George. In every friendship, there are dysfunctional moments, ups and downs, genuine moments and never ending adventures. By definition, a friend is someone to talk to, do things with, be there for each other in time of need and be each others crying shoulder. throughout this novel, Lennie and George display a friendship unlike any other. It is so dysfunctional and rare it makes the reader curiosity why these two are friends. For example, the boss says Well, I never seen one guy take so much trouble for another guy. I just like to know your interest. In this quote rig on page 25, the boss is trying to make sense of their friendship. Even though this quote highlights the distinctiveness of George and Lennies bond, this causes the boss to suspect wrong- doing on Georges part. At the end of the novel, George ends up shooting Lennie.This suddenly displays the dysfunctional and rare qualities in their friendship. There are many ups and downs in Lennie and Georges friendship in addition to it being dysfunctional and rare. Lennie is mentally ill. There is absolutely no rhyme or sympathy behind his actions. For instance, without Lennie, George could Go get a job an work an no trouble. No mess at all and at the end of the month I could take my fifty bucks into town and get any(prenominal) I postulate. This shows Lennie and Georges Relationship being down. Even though Lennie is a huge burden, George ultimately chooses to not be without him. Even though it seems like George is being held down by Lennie, George stays with Lennie because they both want the migrant dream. Someday were gonna get the Jack together, have a little house and a couple of acres an a cow and some pigs and well have a big vegetable patch.Thus, these two cannot run without each other. Lennie and George have a genuine relationship too. George takes really good care of Lennie, nearly like in a maternal way. George says, Lennie, for God sakes dont drink so much, you gonna be sick like you was last night. This shows he cares about Lennie. In the beginning, Lennie assaults a lady by red the front side of her dressoff in their old town Weeds. George couldve easily left Lennie to digest for himself but he realized that wasnt the right thing to do. Lennie hears his dead aunt Clara telling him When he got a piece of pie you always got half or moren half. An if there was any ketchup, why hed give it all to you. As the novel progresses, Lennies past catches up with him and the governing start looking for him. George knows that if it is caught, the officers would throw him in jail and he wouldnt survive.So George shoots Lennie to basically position him out of his misery. Clearly, they have a genuine friendship. With every friendship, there are many adventure s along the way. The novel starts off in a scenic woodsy area by a lake. Lennie and George run outside(a) together from their home town of Weed to run from the authorities and start a new liveliness as migrant workers. When theyve finally reached the barn, they meet new people and build relationships with them. The boss, Curley, Curleys wife, Slim, Crooks, and Carlson. Lennie is always get into trouble and George is always looking to get him out of it. Lennie kills a mouse, strangles Curleys wife and in like manner kills the dog. Although this book had many twist and turns, it was a heart- warming thriller that illustrated what life was like back in the 1930s. it sure wasnt easy but having a dream meant a lot to the characters and made them strive to live their dream.

Reciprocating Engine

224 C H A P T E R 6 RECIPROCATING INTERNAL COMBUSTION ENGINES 6. 1 presentment Perhaps the best-known locomotive in the world is the reciprocating internal flame (IC) locomotive. Virtually every individual who has driven an automobile or pushed a advocator lawnmower has utilise wholeness. By far the most wide employ IC locomotive is the electric arc- inflaming bungleoline locomotive locomotive railway locomotive, which takes us to school and imprint and on pleasure jaunts. Although a nonher(prenominal)wises had do signifi beart contributions, Niklaus Otto is generally attribute with the invention of the railway locomotive and with the recountment of its theoretical rhythm.A nonher important railway locomotive is the reciprocating locomotive railway locomotive that made the name of Rudolf diesel engine famous. The diesel engine engine, the hithorse of the heavy truck industry, is widely determination in industrial index and marine applications. It re l uffd the reciprocating steam engine in railroad locomotives ab away fifty years ag adept and remains dominant in that role today. The diver, speculator chamber, tetchy, and connecting terminal provide the geometric basis of the reciprocating engine. While two-stroke- round of golf engines atomic mo 18 in ex publishditure and of continuing interest, the discussion here will emphasize the more than widely utilize four-stroke- pedal engine.In this engine the plumbers helper undergoes two mechanical make passs for each thermodynamic cycle. The ingestion and capsule growthes fade in the rootage two strokes, and the source and overleap branches in the last two. These processes atomic number 18 made possible by the glassful-slider mechanism, discussed next. 6. 2 The Crank-Slider Mechanism Common to most reciprocating engines is a linkage known as a ice-slider mechanism. Diagramed in compute 6. 1, this mechanism is one of several capable of producing the straight- line, backward-and-forward campaign known as reciprocating.Fundamentally, the crank-slider converts rotational motion into linear motion, or vice-versa. With a plumbers helper as the slider moving inside a o bowling pinionated piston chamber, the mechanism provides the vital capability of a gas engine the ability to compress and expand a gas. Before delving into this aspect of the engine, however, let us examine the crank-slider mechanism more closely. 225 It is evident from Figure 6. 2 that, while the crank arm rotates by dint of and finished 180, the speculator moves from the emplacement known as top-center (TC) to the other extreme, called bottom-center (BC).During this period the diver travels a distance, S, called the stroke, that is twice the length of the crank. For an angulate fastness of the crank, , the crank pin A has a tangential velocity component S/2. It is evident that, at TC and at BC, the crank pin velocity component in the piston direction, and thereo f the piston velocity, is zero. At these re shoots, corresponding to crank angle = 0 and 180, the piston reverses direction. hence as varies from 0 to 180, the piston velocity accele stations from 0 to a maximum and then returns to 0.A similar behavior exists between 180 and 360. The connecting rod is a two-force member hence it is evident that there ar both axial and askance forces on the piston at crank angles other than 0 and 180. These afterwardal forces are, of course, opposed by the cylinder walls. The resulting lateral force component normal to the cylinder wall gives trick pop out to frictional forces between the piston punishing and cylinder. It is evident that the normal force, and thus the frictional force, alternates from one side of the piston to the other during each cycle.Thus the piston motion presents a challenging lubrication problem for the discipline and reducing of both wear and might loss. The position of the piston with respect to the crank center line is devoted by x = (S/2)cos + Lcos ft m (6. 1) where yA = (S/2)sin = Lsin can be drug abuse to eliminate to obtain x/L = (S/2L)cos + 1? (S/2L)2 sin2 ? dl (6. 2) Thus, while the axial component of the motion of the crank pin is primary harmonic, xA = (S/2)cos, the motion of the piston and piston pin is more complex. It may be 226 seen from equating (6. ), however, that as S/L be acts small, the piston motion approaches simple harmonic. This becomes physically evident when it is recognized that, in this de stipulate, the connecting rod angle, , approaches 0 and the piston motion approaches the axial motion of the crank pin. Equations (6. 1) and (6. 2) may be apply to ring component velocities, accele dimensionns, and forces in the engine. The script swept by the piston as it passes from TC to BC is called the piston geological fault, disp. locomotive displacement, DISP, is then the point of intersection of the piston displacement and the number of cylinders, DI SP = (n)(disp).The piston displacement is the product of the piston cross-sectional area and the stroke. The cylinder inside diameter (and, approximately, also the piston diameter) is called its bore. Cylinder bore, stroke, and number of cylinders are commonly quoted in engine specialations a desire with or instead of engine displacement. It will be seen later that the business office proceeds of a reciprocating engine is proportional to its displacement. An engine of historical interest that also utilize the crank-slider mechanism is discussed in the next section. 6. 3 The Lenoir CycleAn early get rolling on of the reciprocating internal burning engine is credited to Etienne Lenoir. His engine, introduced in 1860, used a crank-slider-piston-cylinder arrangement 227 in which a combustible diverseness mode put between the piston and cylinder is ignited after TC. The resulting blaze gas push forces acting on the piston deliver practise by way of the connecting rod to the rotating crank. When the piston is at BC, flame gases are allowed to escape. The rotational momentum of the crank system drives the piston toward TC, expelling additional gases as it goes.A fresh combustible ad exchange is again admitted to the combustion chamber (cylinder) and the cycle is repeated. The theoretical Lenoir cycle, shown in Figure 6. 3 on a compel-volume draw, consists of the inhalation of the breaking liquified (a combustible multifariousness) from state 0 to state 1, a constant-volume temperature and haul scrape from state 1 to state 2, approximating the combustion process, an isentropic expansion of the combustion gases to state 3, and a constant-pressure swelling of residuum gases back to state 0.Note that a portion of the piston displacement, from state 0 to state 1, is used to take in the combustible form and does not participate in the military group stroke from state 2 to state 3. The engine has been called an explosion engine because the power delivered is delinquent only to the extremely fast combustion pressure rise or explosion of the mixture in the confined space of the cylinder. Hundreds of Lenoir engines were used in the ordinal century, but the engine is quite inefficient by todays standards. In 1862, Beau de Rochas pointed out that the 228 fficiency of internal combustion could be markedly purifyd in reciprocating engines by abridgment of the bloodline- discharge mixture antecedent to combustion. In 1876 Niklaus Otto (who is thought to concord been unaware of Rochas? suggestion) demonst driftd an engine that incorporated this important feature, as describe next. 6. 4 The Otto Cycle The Otto cycle is the theoretical cycle commonly used to exist the processes in the bow ignition (SI) internal combustion engine. It is assumed that a fixed mass of expireing fluid is confined in the cylinder by a piston that moves from BC to TC and back, as shown in Figure 6. . The cycle consists of isentropic densification of an transfer- supply mixture from state 1 to state 2, constant-volume combustion to state 3, isentropic expansion of the combustion gases to state 4, and a constant-volume altering system rejection back to state 1. The constant-volume heat rejection is a simple expedient to close the cycle. It obviates the need to represent the complex expansion and outflow of 229 combustion gases from the cylinder at the last of the cycle. Note that the Otto cycle is not concerned with the induction of the ship- provide mixture or with the expulsion of residual combustion gases.Thus only two mechanical strokes of the crank-slider are needed in the Otto cycle, even when it is used to represent an exalted four-stroke-cycle Otto engine. In this case the stay strokes are used to execute the necessary ambition and clear subprograms. Because it involves only two strokes, the Otto cycle may also represent a two-stroke-cycle engine. The two-stroke-cycle engine is in regulation capable of as mu ch have in one rotation of the crank as the four-stroke engine is in two. However, it is difficult to implement because of the necessity of making the intake and stupefy functions a part of those wo strokes. It is wherefore not as lavishlyly developed or widely used as the four-stroke-cycle engine. We will emphasis on the fourstroke- cycle here. The simplest analysis of the Otto cycle assumes calorically perfect melody as the relieve oneselfing fluid in what is called the nimbus Standard cycle analysis. Following the notation of Figure 6. 4, the conglutination process can be represented by the isentropic intercourse for a calorically perfect gas, Equation (1. 21), as p2/p1 = (V1/V2)k dl (6. 3) where the compression dimension, CR = V1/V2, is a fundamental parameter of all reciprocating engines.The diagram shows that the expansion ratio for the engine, V4 /V3, has the alike apprize, V1/V2. The headway volume, V2, is the volume enclosed between the cylinder head and the p iston at TC. Thus the compression ratio may be expressed as the ratio of the sum of the clearance and displacement volumes to the clearance volume CR = V2 + (V1 ? V2)/V2 Thus, for a given displacement, the compression ratio may be outgrowthd by reducing the clearance volume. The readiness of the cycle can be most easily contumacious by considering constantvolume- process heat transfers and the First Law cyclic inviolate relation, Equation (1. ). The heat transferred in the processes 23 and 41 are q23 = cv (T3 ? T2) Btu/lbm kj/kg (6. 4) and q41 = cv (T1 ? T4) Btu/lbm kJ/kg (6. 5) Both the expansion process, 34, and the compression process, 12, are assumed to be isentropic. Thus, by definition, they are both adiabatic. From the cyclic integral, the net work per unit of measurement mass is then w = q23 + q41 = cv (T3 ? T2 + T1 ? T4) Btu/lbm kJ/kg (6. 6) 230 As earlier, the cycle caloric susceptibility is the ratio of the net work to the external heat supplied Otto = w/q23 = cv (T3 ? T2 + T1 ?T4) / cv (T3 ? T2) = 1 + (T1 ? T4) / (T3 ? T2) = 1 ? T1/T2 = 1 ? 1 / CR k-1 dl (6. 7) where Equation (1. 20) has been used to eliminate the temperatures. Equation (6. 7) shows that increasing compression ratio increases the cycle thermal strength. This is true for real engines as well as for the idolized Otto engine. The ship canal in which real spark ignition engine cycles deviate from the theoretical Otto cycle are discussed later. grammatical case 6. 1 An Otto engine takes in an airmanship- go off mixture at 80F and standard standard pressureosphere presssure. It has a compression ratio of 8.Using diffuse Standard cycle analysis, a heating value of 20,425 Btu/lbm, and A/F = 15, determine (a) The temperature and pressure at the end of compression, after combustion, and at the end of the power stroke. (b) The net work per pound of working fluid. (c) The thermal cleverness. Solution We use the notation of Figure 6. 4 (a) p2 = p1(V1/V2)k = 1(8)1. 4 = 18. 38 cash machine T2 = T1(V1/V2)k ? 1 = (540)(8)0. 4 = 1240. 6R T3 = T2 + qa /cv = T2 + (F/A)(HV)k/cp = 1240. 6 + 1. 420,425/150. 24 = 9184R p3 = p2T3 /T2 = 18. 38(9184/1240. 6) = 136. 1 atm T4 = T3 /CRk? 1 = 9184/ 80. 4 = 3997. R p4 = p3 /CRk = 136. 1/81. 4 = 7. 4 atm (b) The constant-volume heat addition is governed by the sack-air ratio and the give notice heating value qa = HV(F/A) = 20,425/15 = 1361. 7 Btu/lbm of air 231 qr = cv (T1 ? T4) = (0. 24/1. 4)( 540 ? 3997. 4) = ? 592. 7 Btu/lbm w = qa + qr = 1361. 7 + ( ? 592. 7) = 769 Btu/lbm (c) The cycle termal efficiency may then be determined from the definition of the heat engine thermal efficiency or Equation (6. 7) th = w/qa = 769/1361. 7 = 0. 565 th = 1 ? 1/80. 4 = 0. 565 _____________________________________________________________________ In view f the discussion of gas properties and dissociation in Chapter 3, the values of T3 and T4 in Example 6. 1 are unrealistically high. Much of the push button released by the arouse w ould go into vibration and dissociation of the gas molecules rather than into the translational and rotational degrees of granting immunity represented by the temperature. As a result, significantly lower temperatures would be obtained. Thus, while the analysis is officially correct, the use of constant-low-temperature heat capacities in the mien Standard cycle makes it a poor model for predicting temperature extremes when high might releases occur.Some improvement is achieved by using constant-hightemperature heat capacities, but the best results would be achieved by the use of real gas properties, as discussed in several of the references. 6. 5 Combustion in a Reciprocating engine The constant-volume heat transfer process at TC in the Otto cycle is an artifice to avoid the difficulties of fashion model the complex processes that take place in the combustion chamber of the SI engine. These processes, in reality, take place over a crank angle span of 30 or more around TC.Let u s consider aspects of these processes and their implementation in more detail. Normally, the mixture in the combustion chamber moldiness have an air-fuel ratio in the neighborhood of the stoichiometric value for satisfactory combustion. A more or slight homogeneous mixture may be produced outside the cylinder in a carburetor, by s het up into the intake copy, or by throttle-body scene into a header serving several intake manifold papers. In the case of the carburetor, fuel is pull into the engine from the carburetor by the low pressure created in a venturi through which the combustion air flows.As a result, increased air flow causes lower venturi pressure and hence increased fuel flow. The fuel system thus serves to provide an air-fuel mixture that remains close to the stoichiometric ratio for a range of air flow rates. Various devices designed into the carburetor further put the fuel flow for the special operating conditions encountered, such as idling and rapid acceleration. Maximum fuel rescue is usually attained with excess air to ensure that all of the fuel is burned. A mixture with excess air is called a consort mixture.The carburetor 232 usually produces this condition in automobiles during normal constant-speed driving. On the other hand, maximum power is achieved with excess fuel to assure that all of the oxygen in the air in the combustion chamber is reacted. It is a matter of exploiting the full power-producing capability of the displacement volume. A mixture with excess fuel is called a fat mixture. The automotive carburetor produces a rich mixture during acceleration by supplying extra fuel to the air entering the intake manifold.The equivalence ratio is sometimes used to characterize the mixture ratio, whether rich or lean. The equivalence ratio, , is delimit as the ratio of the positive fuel-air ratio to the stoichiometric fuel-air ratio. Thus 1 represents a rich mixture and 1 represents a lean mixture. In foothold of air-fuel ra tio, = (A/F)stoich /(A/F). Homogeneous air-fuel mixtures close to stoichiometric may ignite spontaneously (that is, without a spark or other local dexterity source) if the mixture temperature exceeds a temperature called the autoignition temperature.If the mixture is brought to and held at a temperature high than the autoignition temperature, there is a period of delay before spontaneous ignition or autoignition This time time interval is called the ignition delay, or ignition lag. The ignition delay depends on the characteristics of the fuel and the equivalence ratio and usually decreases with increasing temperature. In spark-ignition engines, compression ratios and and then the temperatures at the end of compression are low sufficient that the air-fuel mixture is ignited by the spark secure before spontaneous ignition can occur.SI engines are designed so that a irrupt front will propagate smoothly from the spark scolder into the unburned mixture until all of the mixture h as been ignitied. However, as the flame front progresses, the temperature and pressure of the combustion gases behind it rise due to the release of the chemical energy of the fuel. As the front propagates, it compresses and heats the unburned mixture, sometimes termed the end-gas. Combustion is completed as planned when the front smoothly passes completely through the end-gas without autoignition. However, if the end-gas autoignites, a pinging or low-pitched sound called knap is heard.The avoidance of knock due to autoignition of the end-gas is a major constraint on the design compression ratio of an SI engine. If hot spots or thermally induced compression of the end-gas ignite it before the flame front does, there is a more rapid release of chemical energy from the end-gas than during normal combustion. roast is sometimes thought of as an explosion of the end gas that creates an abrupt pulse and pressure waves that locomote back and forth across the cylinder at high speed, prod ucing the familiar pinging or low-pitched sound associated with knock.Knock not only expurgates engine transactance but produces rapid wear and objectionable noise in the engine. Thus it is important for a SI engine fuel to have a high autoignition temperature. It is therefore important for SI engine fuel to have a high autoignition temperature. Thus the knock characteristics of commercially available fuels limit the maximum allowable design compression ratio for SI engines and hence limit their best efficiency. The octane number is a measure of a gasolines ability to avoid knock. Additives such as tetraethyl choose have been used in the past to suppress engine knock.However, the accumulation of lead in the environment and its penetration into the food cycle has 233 resulted in the phaseout of lead additives. Instead refineries now use appropriate blends of hydrocarbons as a substitute for lead additives in unleaded fuels. The octane number of a fuel is measured in a special var iable-compression-ratio engine called a CFR (Cooperative Fuels Research) engine. The octane rating of a fuel is determined by comparison of its knocking characteristics with those of various mixtures of isooctane, C8H18, and n-heptane, C7H16.One hundred percent isooctane is defined as having an octane number of c because it had the highest resistance to knock at the time the rating system was devised. On the other hand, n-heptane is depute a value of 0 on the octane number scale because of its very poor knock resistance. If a gasoline tested in the CFR engine has the same knock threshold as a blend of 90% isooctane and 10% n-heptane, the fuel is assigned an octane rating of 90. In combustion chamber design, the designer attempts to balance numerous factors to achieve good performance.Design considerations include locating intake valves away from and unblock valves near spark plugs, to pass on end-gas in a relatively cool area of the combustion chamber and thereby suppress hot -surface-induced autoignition tendencies. Valves are, of course, designed as large as possible to reduce induction and exhaust flow restrictions. More than one intake and one exhaust valve per cylinder are now used in some engines to improve ? engine breathing.? In some engines, four valves in a single cylinder are employ for this purpose.The valves are also designed to induce swirl and turbulence to promote mixing of fuel and air and to improve combustion stability and burning rate. Pollution and fuel economy considerations have in juvenile years profoundly influenced overall engine and combustion chamber design. Stratified-charge engines, for example, attempt to provide a locally rich combustion region to dominate peak temperatures and thus suppress nighttime formation. The resulting combustion gases containing unburned fuel then mix with surrounding lean mixture to complete the combustion process, thus eliminating CO and unburned hydrocarbons from the exhaust.These processes occur at lower temperatures than in conventional combustion chamber designs and therefore prevent significant normality reactions. 6. 6 Representing Reciprocating Engine Perfomance In an introductory section, the theoretical work per unit mass of working fluid of the Otto engine was evaluated for a single cycle of the engine, using the cyclic integral of the First Law of Thermodynamics. The work done by pressure forces acting on a piston can also be evaluated as the integral of pdV. It is evident therefore that the work done during a single engine cycle is the area enclosed by the cycle process curl ups on the pressure-volume diagram.Thus, instead of using the cyclic integral or evaluating pdV for each process of the cycle, the work of a reciprocating engine can be found by drawing the theoretical process curves on the p? V diagram and graphically integrating them. such(prenominal) a plot of pressure versus volume for any reciprocating engine, real or theoretical, is called an i ndication diagram. 234 In the nineteenth and early twentieth centuries a mechanical device known as an engine indicator was used to produce indicator cards or diagrams to determine the work per cycle for sulky-running steam and gas reciprocating ngines. The indicator card was attached to a cylinder that rotated back and forth on its axis as the piston oscillated, thus generating a piston position (volume) coordinate. At the same time a pen driven by a pressure signal from the engine cylinder moved parallel to the cylinder axis, scribing the p-V diagram over and over on the card. The work of high speed engines is still evaluated from traces of pressure obtained with electronic sensors and displayed on electronic monitors and through digital techniques.The work done per cycle (from an indicator card, for instance) can be represented as an average pressure times a volume. Because the displacement volumes of engines are usually known, an engine performance parameter known as the incul pate effective pressure, MEP, is defined in price of the piston displacement. The mean effective pressure is defined as the value of the pressure obtained by dividing the net work per cylinder per cycle at a given operating condition by the piston displacement volume MEP = W/disp lbf/ft2 kPa (6. 8)Thus the MEP is a measure of the effectiveness of a given displacement volume in producing net work. The power output of an engine with identical cylinders may be represented as the product of the work per cycle and the number of cycles punish per unit time by the engine. Thus if the engine has n cylinders, each executing N identical thermodynamic cycles per unit time, and delivering W work units per cylinder, with a piston displacement, disp, the power output is given by P = nNW = nN MEP disp ft-lbf /min kW (6. 9)Expressed for the entire engine, the engine displacement is DISP = ndisp and the engine work is MEP DISP. Hence the engine power is P = N MEPDISP ft-lbf /min kW (6. 10) whe re N, the number of thermodynamic cycles of a cylinder per unit time, is the number of crank-shaft revolutions per unit time for a two-stroke-cycle engine and one-half of the revolutions per unit time for a four-stroke-cycle engine. The factor of ? for the four-stroke-cycle engine arises because one thermodynamic cycle is executed each time the crank rotates through two revolutions. example 6. 2What is the displacement of an engine that develops 60 horsepower at 2500 revolutions per minute in a four-stroke-cycle engine having an MEP of 120 pounds per square edge? 235 Solution From Equation (6. 10), the displacement of the engine is DISP = P/(N MEP) = (60)(33,000)(12)/(2500/2)(120) = 158. 4 in3 Checking units (HP)(ft-lbf/HP-min)(in/ft)/(cycles/min)(lbf/in2) = in3 _____________________________________________________________________ If the work is evaluated from an indicator diagram the work is called indicated work the MEP is called the indicated mean effective pressure, IMEP and the power is indicated power, IP.Note that the indicated work and power, being associated with the work done by the combustion chamber gases on the piston, do not account for frictional or mechanical losses in the engine, such as piston-cylinder friction or the drag of moving parts (like connecting rods) as they move through air or lubricating oil. Brake Performance Parameters Another way of evaluating engine performance is to attach the engine output shaft to a device known as a dynamometer, or halt. The dynamometer measures the crookedness, T, utilise by the engine at a given rotational speed.The power is then calculated from the relation P = 2rpm T ft-lbf /min N-m/min (6. 11) A simple device called a prony stop, which was used in the past, demonstrates the concept for the measurement of the shaft tortuosity of engines. Figure 6. 5 shows the prony halt configuration in which a stationary metal band wrapped around the rotating flywheel of the engine resists the torque tran smitted to it by friction. The product of the force measured by a spring scale, w, and the moment arm, d , gives the resisting torque. The power dispel is then given by 2(rpm)w d.Modern devices such as water halts and electrical dynamometers long ago replaced the prony pasture brake. The water brake is like a centrifugal water pump with no outflow, attach on low-friction bearings, and driven by the test engine. As with the prony brake, the force required to resist turning of the brake (pump) housing provides the torque data. This, together with speed measurement, yields the power output from Equation (6. 11). The power dissipated appears as increased temperature of the water in the brake and heat transfer from the brake. Cool water is circulated slowly through the brake to maintain a steady operating condition.The torque measured in this way is called the brake torque, BT, and the resulting power is called the brake power, BP. To summarize while indicated parameters relate to ga s forces in the cylinder, brake parameters deal with output shaft forces. Thus the brake power differs from the indicated power in that it accounts for the effect of all of the energy losses in the engine. The difference between the two is referred to as the friction power, FP. Thus FP = IP ? BP. 236 Friction power varies with engine speed and is difficult to measure directly.An engine is sometimes driven without fuel by a motor-dynamometer to evaluate friction power. An alternative to using friction power to relate brake and indicated power is through the engine mechanical efficiency, m m = BP/IP dl (6. 12) Because of friction, the brake power of an engine is always little(prenominal) than the indicated power hence the engine mechanical efficiency must be less than 1. Clearly, mechanical efficiencies as close to 1 as possible are desired. The engine indicated power can also be expressed in terms of torque, through Equation (6. 11). Thus an indicated torque, IT, can be defined.Simi larly, a brake mean effective pressure, BMEP, may be defined that, when multiplied by the engine displacement and speed, yields the brake power, analogous to Equation (6. 10). Table 6. 1 summarizes these and other performance parameters and relations. The thermal efficiency, as for other engines, is a measure of the fuel economy of a reciprocating engine. It tells the amount of power output that can be achieved for a given rate of heat release from the fuel. The rate of energy release is, in turn, the product of the rate of fuel flow and the fuel heating value.Thus, for a given thermal efficiency, power output can be increased by employing a high fuel flow rate and/or selecting a fuel with a high heat of combustion. If the thermal efficiency is evaluated using the brake power, it is called the brake thermal efficiency, BTE. If the evaluation uses the indicated power, it is called the indicated thermal efficiency, ITE. 237 It is common practice in the reciprocating engine field to re port engine fuel economy in terms of a parameter called the specific fuel consumption, SFC, analogous to the thrust specific fuel consumption used to describe jet engine performance.The specific fuel consumption is defined as the ratio of the fuel-mass flow rate to the power output. Typical units are pounds per horsepower-hour or kilograms per kilowatt-hour. Obviously, good fuel economy is indicated by low values of SFC. The SFC is called brake specific fuel consumption, BSFC, if it is defined using brake power or indicated specific fuel consumption, ISFC, when based on indicated power. The SFC for a reciprocating engine is analogous to the heat rate for a steam power plant in that both are measures of the rate of energy supplied per unit of power output, and in that low values of both are desirable.volumetrical Efficiency The theoretical energy released during the combustion process is the product of the mass of fuel contained in the combustion chamber and its heating value if the fuel is completely reacted. The more air that can be packed into the combustion chamber, the Table 6. 1 Engine Performance Parameters Indicated Brake Friction Mean effective pressure IMEP BMEP FMEP = IMEP BMEP m = BMEP / IMEP Power IP BP FP = IP BP m = BHP / IHP Torque IT BT FT = IT BT m = BT / IT Thermal efficiency ITE BTE m = BTE / ITE Specific fuel consumption ISFC BSFC m = ISFC / BSFC more fuel that can be burned with it.Thus a measure of the efficiency of the induction system is of great importance. The volumetric efficiency, v, is the ratio of the actual mass of mixture in the combustion chamber to the mass of mixture that the displacement volume could hold if the mixture were at ambient (free-air) density. Thus the average mass-flow rate of air through a cylinder is v (disp) aN. Pressure losses across intake and exhaust valves, combustion-chamber clearance volume, the influence of hot cylinder walls on mixture density, valve clock, and gas inertia effects all influence th e volumetric efficiency.EXAMPLE 6. 3 A six-cylinder, four-stroke-cycle SI engine operates at 3000 rpm with an indicated mean effective pressure of five atmospheres using octane fuel with an equivalence ratio 238 of 0. 9. The brake torque at this condition is 250 lbf? ft. , and the volumetric efficiency is 85%. Each cylinder has a five inch bore and 6 inch stroke. Ambient conditions are 14. 7 psia and 40F. What is the indicated horsepower, brake horsepower, and friction horsepower the mechanical efficiency the fuel flow rate and the BSFC? Solution The six cylinders have a quantity displacement ofDISP = 6? 52? 6/4 = 706. 86 in3 Then the indicated horsepower is IP = MEP? DISP? N /12? 33,000 lbf /in2in3cycles/min/in/ftft-lbf /HP-min = (5)(14. 7)(706. 86)(3000/2)/12? 33,000 = 196. 8 horsepower The brake horsepower, from Equation (6. 11), is BP = 2 ? 3000 ? 250 / 33,000 = 142. 8 horsepower Then the friction power is the difference between the indicated and brake power FP = 196. 8 ? 142. 8 = 54 horsepower and the mechanical efficiency is m = 142. 8/196. 8 = 0. 726 The ambient density is a = 14. 7 ? 144/ 53. 3 ? 500 = 0. 0794 lbm /ft3 nd the mass flow rate of air to the engine is ma = 0. 85? 0. 0794? 706. 86? (3000/2)/1728 = 41. 4 lbm /min For octane the stoichiometric reaction equation is C8H18 + 12. 5O2 + (12. 5? 3. 76)N2 8CO2 + 9H2O + (12. 5? 3. 76)N2 The fuel-air ratio is then F/A = 0. 9? (8? 12) + (18? 1)/12. 5(32 + 3. 76? 28) = 0. 0598 lbm-fuel /lbm-air 239 The fuel flow rate is mf = ma (F/A) = 41. 4 ? 0. 0598 = 2. 474 lbm /min The brake specific fuel consumption is BSFC = 60 mf /BHP = 60? 2. 474/142. 8 = 1. 04 lbm /BHP-hr ____________________________________________________________________ 6. Spark- ignition system Engine Performance A typical indicator diagram showing intake and exhaust processes, valve actuation, and spark timing for a four-stroke-cycle SI engine is shown in Figure 6. 6. It is assumed that an appropriate air-fuel mixture is supplied from a carburetor through an intake manifold to an intake valve, IV, and that the combustion gas is discharged through an exhaust valve, EV, into an exhaust manifold. The induction of the air-fuel mixture starts with the opening of the intake valve at point A just before TC.As the piston sweeps to the right, the mixture is drawn into the cylinder through the IV. The pressure in the cylinder is somewhat below that in the intake manifold due to the pressure losses across the intake valve. In order to use the momentum of the mixture inflow through the valve at the end of the intake stroke to improve the volumetric efficiency, intake valve plosive consonant is delayed to shortly after BC at point B. Power supplied from inertia of a flywheel (and the other rotating masses in the engine) drives the piston to the left, compressing and raising the temperature of the trapped mixture.The combustion process in a properly operating SI engine is progressive in that the reaction starts at the spark plu g and progresses into the unburned mixture at a finite speed. Thus the combustion process takes time and cannot be executed instantaneously as implied by the theoretical cycle. In order for the process to take place as near to TC as possible, the spark plug is fired at point S. The number of degrees of crank rotation before TC at which the spark occurs is called the ignition advance. Advances of 10 to 30 are common, depending on speed and load.The spark advance may be controlled by devices that sense engine speed and intake manifold pressure. Microprocessors are now used to control spark advance and other functions, based on almost instantaneous engine performance measurements. Recalling the slider-crank analysis, we observ that the piston velocity at top center is momentarily zero as the piston changes direction. Therefore no work can be done at this point, regardless of the magnitude of the pressure force. Thus, to maximize the work output, it is desired to have the maximum cylind er pressure occur at rough 20 after TC.Adjustment of the spark advance (in degrees before TC) allows some control of the combustion process and the timing of peak pressure. For a fixed combustion duration, the combustion crank-angle interval must increase with engine speed. As a consequence, the ignition advance must increase with increasing engine speed to 240 maintain optimum timing of the peak pressure. Following combustion, the piston continues toward bottom center as the high pressure gases expand and do work on the piston during the power stroke. As the piston approaches BC, the gases do little work on the piston as its velocity again approaches zero.As a result, not much work is lost by early opening of the exhaust valve before BC (at point E) to start the blowdown portion of the exhaust process. It is expedient to sacrifice a little work during the end of the power stroke in order to reduce the work needed to overpower an otherwise-high exhaust stroke cylinder pressure. In ertia of the gas in the cylinder and resistance to flow through the exhaust valve opening slow the drop of gas pressure in the cylinder after the valve opens. Thus the gases at point E are at a pressure above the exhaust manifold pressure and, during blowdown, rush out through the EV at high speed.Following blowdown, gases remaining in the cylinder are then expelled as the piston returns to TC. They remain above exhaust manifold pressure until reaching TC because of the flow resistance of the exhaust valve. The EV closes shortly after TC at point C, terminating the exhaust process. The period of coincide at TC between the intake valve opening at point A and exhaust valve gag law at point C in Figure 6. 6 allows more time for the intake and exhaust processes at high engine speeds, when about 10 milliseconds may be available for these processes.At low engine speed and at idling there may be some mixture loss through the exhaust valve and discharge into the intake manifold during thi s valve overlap period. The combined exhaust and induction processes are seen to form a ? pumping iteration? that traverses the p-V diagram in a counterclockwise direction and therefore 241 represents work foreplay rather than work production. The high the exhaust stroke pressure and the lower the intake stroke pressure, the greater the area of the pumping loop and hence the greater the work that must be supplied by the power loop (clockwise) to compensate.Great attention is therefore paid to valve design and other engine characteristics that influence the exhaust and induction processes. Volumetric efficiency is a major parameter that indicates the degree of success of these efforts. Performance Characteristics A given exaltation Otto-cycle engine produces a certain amount of work per cycle. For such a cycle, MEP = W/disp is a constant. study the power equations (6. 9) and (6. 11) shows that the average torque is proportional to MEP and independent of engine engine speed.There fore power output for the ideal engine is directly proportional to the number of cycles executed per unit time, or to engine speed. Thus an Otto engine has ideal torque and power characteristics, as shown by the solid lines in Figure 6. 7. The characteristics of real engines (represented by the dashed lines) tend to be similar in nature to the ideal characteristics but suffer from speed-sensitive effects, especially at low or high speeds. Torque and power characteristics for a 3. 1 liter V6 engine (ref. 9) are shown by the solid lines in Figure 6. 8.Note the flatness of the torque-speed curve and the expected peaking of the power curve at higher speed than the torque curve. Rather than present graphical characteristics such as this in their 242 brochures, automobile manufacturers usually present only values for the maximum power and torque and the speeds at which they occur. Engine characteristics such as those shown in the figure are invaluable to application engineers seeking a a dequate engine for use in a product. 6. 8 The Compression- sack or diesel engine Cycle The ideal diesel cycle differs from the Otto cycle in that combustion is at constant pressure rather than constant volume.The ideal cycle, shown in Figure 6. 9, is commonly implemented in a reciprocating engine in which air is close without fuel from state 1 to state 2. With a typically high compression ratio, state 2 is at a temperature high enough that fuel will ignite spontaneously when sprayed directly into the air in the combustion chamber from a high-pressure fuel injection system. By controlling the fuel injection rate and thus the rate of chemical energy release in relation to the rate of expansion of the combustion gases after state 2, a constant243 pressure process or other energy release pattern may be achieved as in Figure 6. . For example, if the energy release rate is high, then pressure may rise, as from 2 to 3, and if low may fall to 3. Thus constant-pressure combustion made pos sible by controlling the rate of fuel injection into the cyclinder implies the use of a precision fuel injection system. Instead of injecting fuel into the high-temperature compressed air, the cycle might be executed by compression of an air-fuel mixture, with ignition occurring either spontaneously or at a hot spot in the cylinder near the end of the compression process.Inconsistency and unpredictability of the start of combustion in this approach, due to variations in fuel and operating conditions, and to lack of control of the rate of heat release with the first step of severe knock, makes the operation of such an engine unreliable, at the least, and also limits the maximum compression ratio. The diesel engine engine therefore usually employs fuel injection into compressed air rather than carbureted mixture formation. In the Air Standard cycle analysis of the diesel engine cycle, the heat addition process is at constant pressure q23 = cp(T3 ? T2) Btu/lbm kJ/kg (6. 13) nd, as with the Otto cycle, the closing process is at constant volume q41 = cv(T1 ? T4) Btu/lbm kJ/kg (6. 14) 244 The net work and thermal efficiency are then w = q23 + q41 = cp(T3 ? T2) + cv(T1 ? T4) = cvT1k(T3/T1 ? T2/T1) + 1 ? T4/T1 Btu/lbm kJ/kg (6. 15) Diesel = w/q23 = 1 + q4-1/q23 = 1 + (cv/cp)(T1 ? T4)/(T3 ? T2) = 1 ? (1/k)(T1/T2)(T4/T1 ? 1)/(T3/T2 ? 1) dl (6. 16) The expressions for the net work and cycle efficiency may be expressed in terms two parameters, the compression ratio, CR = V1/V2 (as defined earlier in treating the Otto cycle) and the cutoff ratio, COR = V3/V2.The temperature ratios in Equations (6. 15) and (6. 16) may be replaced by these parameters using, for the constant-pressure process, COR = V3/V2 = T3/T2 and by expanding the following identity T4 /T1 = (T4/T3)(T3/T2)(T2 /T1) = (V3 /V4)k-1(V3/V2)(V1/V2)k-1 = (V3/V4)(V1/V2)k-1COR = (COR)k-1COR = bob where the product of the volume ratios was simplified by recognizing that V4 = V1. Thus the nondimensionalized net work and Diesel-cycle thermal efficiency are given by w /cvT1 = kCRk-1(COR ? 1) + (1 ? CORk) dl (6. 17) and Diesel = 1 ? (1/k)(CORk ? 1)/(COR ? 1)/CRk-1 dl (6. 8) where the cutoff ratio, COR, is the ratio of the volume at the end of combustion, V3, to that at the start of combustion, V2. Thus the cutoff ratio may be thought of as a measure of the duration of fuel injection, with higher cutoff ratios corresponding to longer combustion durations. 245 Diesel-cycle net work increases with both compression ratio and cutoff ratio. This is readily seen graphically from Figure 6. 9 in terms of p-V diagram area. As with the Otto cycle, increasing compression ratio increases the Diesel-cycle thermal efficiency. Increasing cutoff ratio, however, decreases thermal efficiency.This may be rationalized by observing from the p-V diagram that much of the additional heat supplied when injection is continued is spurned at increasingly higher temperatures. Another view is that heat added late in the e xpansion process can produce work only over the remaining part of the stroke and thus adds less to net work than to heat rejection. EXAMPLE 6. 4 A Diesel engine has a compression ratio of 20 and a peak temperature of 3000K. Using an Air Standard cycle analysis, estimate the work per unit mass of air, the thermal efficiency, the combustion pressure, and the cutoff ratio.Solution Assuming an ambient temperature and pressure of 300K and 1 atmosphere, the temperature at the end of the compression stroke is T2 = (300)(20)1. 4 ? 1 = 994. 3K and the combustion pressure is p2 = (1)(20)1. 4 = 66. 3 atm Then the cutoff ratio is V3/V2 = T3/T2 = 3000/994. 3 = 3. 02 The expansion ratio is calculated as follows V4 /V3 = (V1/V2)/(V3 /V2) = 20/3. 02 = 6. 62 T4 = T3 (V3 /V4)1. 4 ? 1 = 3000/6. 620. 4 = 1409K w = 1. 005(3000 ? 994. 3) + (1. 005/1. 4)(300 ? 1409) = 1219. 6 kJ/kg qa = 1. 005(3000 ? 994. 3) = 2015. 7 kJ/kg th = w/qa = 1219. /2015. 6 = 0. 605, or 60. 5% ___________________________________ __________________________________ 246 6. 9 equivalence Otto-Cycle and Diesel-Cycle Efficiencies A reasonable question at this point is Which cycle is more efficient, the Otto cycle or the Diesel cycle? Figure 6. 10 assists in examining this question. In general notation, the cycle efficiency may be written as th = wnet /qin = wnet /(wnet + qout) = 1 /(1 + qout /wnet) dl (6. 19) Comparing the Otto cycle 1? 2? 3? 4 and the Diesel cycle with the same compression ratio 1? 2? 3? , we see that both have the same heat rejection but that the Otto cycle has the higher net work. Equation (6. 19) then shows that, for the same compression ratio, the Otto cycle has the higher efficiency. It has been observed that Diesel-cycle efficiency decreases with increasing cutoff ratio for a given compression ratio. Let us examine the limit of the Diesel-cycle efficiency for constant CR as COR approaches its minimum value, 1. We may write Equation (6. 18) as Diesel = 1 ? 1 /(kCRk-1) f (COR) where f(COR) = (CORk ? 1)/(COR ? 1). Applying LHospitals rule, with primes 247 esignating differentiation with respect to COR, to the limit of f(COR) as COR 1, yields lim f(COR) = lim (CORk ? 1)/ Lim (COR? 1) = lim kCORk ? 1 = k COR1 COR1 COR1 and limDiesel = 1 ? 1 /CRk ? 1 COR1 = Otto Thus the limit of the Diesel-cycle efficiency as COR approaches 1 is the Otto cycle efficiency. Hence Equation (6. 18) shows that the efficiency of the Diesel cycle must be less than or equal to the Otto-cycle efficiency if both engines have the same compression ratio, the same conclusion we reached by examination of the p-V diagram.Suppose, however, that the compression ratios are not the same. Compare the Otto cycle 1? 2? 3? 4 with the Diesel cycle 1? 2? 3? 4 having the same maximum temperature in Figure 6. 10. The Otto cycle has a smaller area, and therefore less work, than the Diesel cycle, but the same heat rejection. Equation (6. 19) demonstrates that the Otto cycle has a lower thermal efficiency than the Di esel cycle with the same maximum temperature. The conclusion that must be drawn from the above comparisons is quite clear. As in most comparative engineering studies, the result depends on the ground ules which were adopted at the start of the study. The Otto cycle is more efficient if the compression ratio is the same or greater than that of the competing Diesel cycle. but knock in spark-ignition (Otto) engines limits their compression ratios to about 12, while Diesel-engine compression ratios may exceed 20. Thus, with these higher compression ratios, the Air Standard Diesel-cycle efficiency can exceed that of the Otto cycle. In practice, Diesel engines tend to have higher efficiencies than SI engines because of higher compression ratios. 6. 0 Diesel-Engine Performance In 1897, five years after Rudolph Diesels first patents and twenty-one years after Ottos introduction of the spark-ignition engine, Diesels compression-ignition engine was proven to develop 13. 1 kilowatts of power with an unprecedented brake thermal efficiency of 26. 2% (ref. 7). At that time, most steam engines operated at thermal efficiencies below 10 % and the best gas engines did not perform much better than the steam machines. Diesel claimed (and was widely believed) to have developed his engine from the principles expounded by Carnot.He had developed the rational engine. Whether his claims were exaggerated or not, Diesels acclaim was well deserved. He had developed an engine that operated at unprecedented temperatures and pressures, had proven his concept of ignition of fuel by injection into the compressed high-temperature air, and had overcome the formidable problems of injecting a variety of fuels in appropriate 248 amounts with the precise timing required for satisfactory combustion. His is a fascinating story of a brilliant and dedicated engineer (refs. 7, 8).In the Diesel engine, the high air temperatures and pressures previous to combustion are attributable to the compression of air solely rather than an air-fuel mixture. Compression of air alone eliminates the possibility of autiognition during compression and makes high compression ratios possible. However, because of the high pressures and temperatures, Diesel engines must be designed to be structurally more rugged. Therefore, they tend to be heavier than SI engines with the same brake power. The energy release process in the Diesel engine is controlled by the rate of injection of fuel.After a brief ignition lag, the first fuel injected into the combustion chamber autoignites and the resulting high gas temperature sustains the combustion of the remainder of the fuel stream as it enters the combustion chamber. Thus it is evident that the favorable fuel characteristic of high autoignition temperature for an SI engine is an admonitory characteristic for a Diesel engine. In the Diesel engine, a low autoignition temperature and a short ignition delay are desirable. Knock is possible in the Diesel engine, bu t it is due to an entirely different cause than knock in a spark-ignition engine.If fuel is ignited and burns as rapidly as it is injected, then smooth, knock-free combustion occurs. If, on the other hand, fuel accumulates in the cylinder before ignition due to a long ignition lag, an explosion or detonation occurs, producing a loud Diesel knock. The cetane number is the parameter that identifies the ignition lag characteristic of a fuel. The cetane number, like the octane number, is determined by testing in a CFR engine. The ignition lag of the test fuel is compared with that of a mixture of n-cetane, C16H34, and heptamethylnonane, HMN (ref. 0). Cetane, which has good ignition qualities, is assigned a value of 100 and HMN, which has poor knock behavior, a value of 15. The cetane number is then given by the sum of the percentage of n-cetane and 0. 15 times the percentage of HMN in the knock-comparison mixture. A cetane number of 40 is the minimum allowed for a Diesel fuel. 6. 11 Sup erchargers and Turbochargers The importance of the volumetric efficiency, representing the efficiency of induction of the air-fuel mixture into the reciprocating-engine cylinders, was discussed earlier.Clearly, the more mixture mass in the displacement volume, the more chemical energy can be released and the more power will be delivered from that volume. During the Second World War, the mechanical supercharger was sometimes used with SI aircraft engines to increase the power and operational ceiling of American airplanes. Today supercharging is used with both Diesel engines and SI engines. The supercharger is a compressor that supplies air to the cylinder at high pressure so that the as density in the cylinder at the start of compression is well above the free-air density. The piston exhaust gases are allowed to expand freely to the atmosphere through the exhaust manifold and tailpipe. The supercharger is usually driven by a belt or gear train from the engine crank shaft. 249 Figure 6. 11 shows a modification of the theoretical Otto cycle to accommodate mechanical supercharging. The supercharger supplies air to the engine cyclinders at pressure p7 in the intake process 7 1. The processes 4 5 6 purge most of the combustion gas from the cylinder.The most striking change in the cycle is that the induction-exhaust loop is now traversed counterclockwise, indicating that the cylinder is delivering net work during these processes as well as during the compressionexpansion loop. It should be remembered, however, that part of the cycle indicated power must be used to drive the external supercharger. The turbosupercharger or turbocharger, for short, is a supercharger driven by a turbine using the exhaust gas of the reciprocating engine, as shown schematically in Figure 6. 12. A cutaway view of a turbocharger is shown in Figure 6. 3(a). Figure 6. 13(b) presents a diagram for the turbocharger. Compact turbochargers commonly increase the brake power of an engine by 30% o r more, as shown in Figure 6. 8, where the performance of an engine with and without turbocharging is compared. There, a substantial increase in peak torque and flattening of the torque-speed curve due to turbocharging is evident. For a supercharged engine, the brake power, BP, is the indicated power (as in Figure 6. 11) less the engine friction power and the supercharger shaft power BP = DISP IMEP N ? Pm ?FP ft-lbf /min kJ/s (6. 15) 250 where Pm is the supercharger-shaft mechanical power supplied by the engine (0 for a turbocharger). The IMEP includes the positive work contribution of the exhaust loop. The exhaust back pressure of the reciprocating engine is higher with a turbocharger than for a naturally aspirated or mechanically supercharged engine because of the drop in exhaust gas pressure through the turbine. The engine brake power increases primarily because of a higher IMEP due to the added mass of fuel and air in the cylinder during combustion.Intercooling between the co mpressor and the intake manifold may be used to further increase the cylinder charge density. Turbocharging may increase engine efficiency, but its primary benefit is a substantial increase in brake power. In a turbocharged engine, a wastegate may be required to bypass engine exhaust gas around the turbine at high engine speeds. This becomes necessary when the compressor raises the intake manifold pressure to excessively high levels, causing engine knock or threatening component damage. Thirty to forty percent of the exhaust flow may be bypassed around the turbine at maximum speed and load (ref. ). 251 252 6. 12 The Automobile Engine and Air Pollution Since the Second World War, concern for environmental pollution has grown from acceptance of the status quo to apprehension and militance of national and international scope. Among other sources, causes of the well-known Los Angeles smog problem were identified as hydrocarbons (HC) and oxides of newton (nighttime) in exhaust emissio ns from motor vehicle reciprocating engines. As a result, national and California automobile air pollution limits for automobiles have been established and toughened.Prior to the Clean Air Act of 1990, the U. S. federal exhaust-gas emissions standards limited unburned hydrocarbons, carbon monoxide, and oxides of nitrogen to 0. 41, 3. 4, and 1. 0 g/mile, respectively. According to reference 12, today it takes 25 autos to emit as much CO and unburned hydrocarbons and 4 to emit as much dark as a single car in 1960. The reference anticipated that, led by existing California law and other factors, future engine designs should be targeted toward satisfying a tailpipe standard of 0. 5, 3. 4, 0. 4 g/mile. Indeed, the 1990 Clean Air Act (refs. 15,16) undertake these limits for the first 50,000 miles or five years of operation for all passenger cars manufactured after 1995. In addition to the regulations on gaseous emissions, the Clean Air Act of 1990 adopted the California standard for pa rticulate matter of 0. 08 g/mile for passenger cars. The standards on particulates are particularly difficult for the Diesel engine, because of its of soot-producing tendency.The automobile air pollution problem arises in part because the reactions in the exhaust system are not in chemical equilibrium as the gas temperature drops. Oxides of nitrogen, once formed in the cylinder at high temperature, do not return to equilibrium concentrations of nitrogen and oxygen in the cooling exhaust products. Likewise, CO formed with rich mixtures or by dissociation of CO2 in the cylinder at high temperature does not respond rapidly to an infusion of air as its temperature drops in the exhaust system. Their concentrations may be thought of as constant or frozen.Unburned hydrocarbons are produced not only by rich combustion but also by unburned mixture lurking in crevices (such as between piston and cylinder above the top piston ring), by lubricating oil on cylinder walls and the cylinder head th at absorbs and desorbs hydrocarbons before and after combustion, and by transient operating conditions. Starting in 1963, positive crankcase ventilation was used in all new cars to duct fuel-rich crankcase gas previously vented to the atmosphere back into the engine intake system. Later in the ? 0s, various fixes were adopted to comply with regulation of tailpipe unburned hydrocarbons and CO, including lowering compression ratios. In 1973, NOx became federally regulated, and exhaust gas recirculation (EGR) was employed to reduce NOx formation through reduced combustion temperatures. At the same time, HC and CO standards were reduced further, leading to the use of the oxidizing catalytic convertor. Introduction of air wield into the tailpipe provided additional oxygen to assist in completion of the oxidation reactions.In 1981, a reducing catalytic converter came into use to reduce NOx further. This device does not perform well in an oxidizing atmosphere. As a result, two-stage cata lytic converters were applied, with the first stage reducing NOx in a near-stoichiometric mixture and the 253 second oxidizing the combustibles remaining in the exhaust with the help of air introduced between the stages. This fresh air does not the increase NOx significantly, because of the relatively low temperature of the exhaust.The three-way catalytic converter using several exotic metal catalysts to reduce all three of the gaseous pollutants was also introduced. The use of catalytic converters to deal with all three pollutants brought about significant simultaneous reductions in the three major gaseous pollutants from automobiles. This allowed fuel-economy-reducing modifications that had been introduced earlier to satisfy emission reduction demands to be eliminated or relaxed, leading to further improvements in fuel economy.Catalytic converters, however, require precise control of exhaust gas oxygen to near-stoichiometric mixtures. The on-board computer has made possible contro l of mixture ratio and spark timing in response to censor outputs of intake manifold pressure, exhaust gas oxygen, engine speed, air flow, and incipient knock. The oxygen, or lambda, censor located in the exhaust pipe upstream of the three-way converter or between the two-stage converters is very sensitive to transition from rich to lean exhaust and allows close computer control of the mixture ratio to ensure proper operation of the catalytic converter.Computer control of carburetors or fuel injection as well as other engine functions has allowed simultaneous improvement in fuel economy and emissions in recent years. Thus, while emissions have been drastically reduced since 1974, according to reference 11 the EPA heterogeneous fuel economy of the average U. S. passenger car has nearly doubled although this improvement has not come from the engine alone. Despite the hard-won gains in emissions control and fuel economy, further progress may be expected. EXAMPLE 6. 5 The 1990 NOx emi ssions standard is 0. grams per mile. For an automobile burning stoichiometric octane with a fuel mileage of 30 mpg, what is the maximum tailpipe concentration of NOx in parts per million? Assume that NOx is represented by NO2 and that the fuel density is 692 kilograms per cubic meter. Solution For the stoichiometric combustion of octane, C8H18, the air-fuel ratio is 15. 05 and the molecular weight of combustion products is 28. 6. The consumption of octane is mf = (692)(1000)(3. 79? 10-3)/ 30 = 87. 4 g/mile Note (kg/m3)(g/kg)(m3/gal)/(mile/gal) = g/mile. The concentration of NOx is the ratio of the number of moles of NOx to moles of combustion gas products mole Nox /mole cg = (mNOx /mf)(mf / mcg)(Mcg /MNOx) = (0. 4/87. 4)(28. 6/46)/ (15. 05 + 1) = 0. 0001773 254 or 177. 3 parts per million (ppm). _____________________________________________________________________ Bibliography and References 1. Heywood, John B. , inner Combustion Engine Fundamentals. refreshful York McGraw-Hill, 1 988. 2. Ferguson, Colin R. , Internal Combustion Engines. New York Wiley, 1986. 3. Adler, U. , et al. , self-propelling Handbook, 2nd ed. Warrendale, Pa. Society of self-propelling Engineers. , 1986. 4. Lichty, Lester C. , Internal Combustion Engines. New York McGraw Hill, 1951. 5. Crouse, William H. , Automotive Engine Design. New York McGraw-Hill, 1970. 6. Obert, Edward, Internal Combustion Engines, Analysis and Practice. Scranton, Pa. International Textbook Co. , 1944. 7. Grosser, Morton, Diesel The Man and the Engine. New York Atheneum, 1978. 8. Nitske, W. Robert, and Wilson, Charles Morrow, Rudolph Diesel Pioneer of the Age of Power. Norman, Okla. University of Oklahoma Press, 1965. 9. Demmler, Albert W. Jr. , et al. , ? 989 Technical Highlights of Big-three U. S. Manufacturers,? Automotive Engineering. Vol. 96, No. 10, October 1988, p. 81. 10. Anon. , ? Ignition Quality of Diesel Fuels by the Cetane Method,? ASTM D 613-84, 1985 Annual Book of ASTM Standards, Section 5. 11. A mann, Charles A. , ? The Automotive Spark Ignition Engine-A Historical Perspective,? American Society of Mechanical Engineers, ICE-Vol. 8, Book No. 100294, 1989. 12. Amann, Charles A. , ? The Automotive Spark-Ignition Engine-A Future Perspective,? Society of Automotive Engineers Paper 891666, 1989. 13. Amann, Charles A. , ?The Passenger Car and the Greenhouse Effect,? Society of Automotive Engineers Paper, 1990. 14. Taylor, Charles Fayette, The Internal Combustion Engine in Theory and Practice, 2nd ed. , revised. Cambridge, Mass. MIT Press, 1985. 255 15. Public Law 101-549, ? An Act to Amend the Clean Air Act to fork up for Attainment and Maintenance of Health, Protection, National Air Quality Standards, and Other Purposes,? November 15, 1990. 16. Anon. , ? Provisions? Clean Air Amendments,? Congressional Quarterly, November 24, 1990. EXERCISES 6. 1 Plot dimensionless piston position against crank angle for S/2L = 0. , 0. 4, 0. 3, and 0. 2. 6. 2* cause expressions for the piston velocity and acceleration as a function of the crank angle, constant angular velocity, and S/2L ratio. Use a spreadsheet to calculate and plot velocity and acceleration against crank angle for S/2L = 0. 5, 0. 4, 0. 3, and 0. 2. 6. 3 Determine the equation for the piston motion for a scotch yoke mechanism in terms of crank angle. Obtain an equation for the piston velocity for a crank that turns with a given angular velocity, . 6. 4 Derive an equation for the Otto-engine net work by integration of pdV for the Air Standard cycle.Compare with Equation (6. 6). 6. 5* Use a spreadsheet to calculate and plot cycle efficiency as a function of compression ratio for the Diesel cycle for cutoff ratios of 1, 2, and 3. Indentify the Otto-cycle efficiency on the plot. Explain and show graphically from the plot how a Diesel engine can be more efficient than an Otto engine. 6. 6 A single-cylinder Air Standard Otto engine has a compression ratio of 8. 5 and a peak temperature of 3500F at ambient cond itions of 80F and one atmosphere. Determine the cycle efficiency, maximum cylinder pressure, and mean effective pressure. 6. A six-cylinder engine with a compression ratio of 11 runs at 2800 rpm at 80F and 14. 7 psia. Each cylinder has a bore and stroke of three inches and a volumetric efficiency of 0. 82. Assume an Air Standard, four-stroke Otto cycle _______________________ * Exercise numbers with an asterisk indic