The Theories Of Motivation Psychology Essay

The Theories Of Motivation Psychology Essay Motivation can be defined as giving a reason, incentive, enthusiasm or interest that causes a person to adopt a specific action or behavior. A simple example could be that our act of eating is motivated by hunger. We can classify motivation into two main types: Intrinsic motivation: when people do something for pleasure, importance or desire (internal) Extrinsic motivation: when external factors motivate a person to adopt a certain act or behavior(external) (Lionel, 1994) Theories of motivation: Incentive theory: A tangible or an intangible reward is given after the occurrence of an action/behavior with the intention of causing the behavior/action to occur again. Some studies show that if the reward is given quickly, the effect is greater than if the incentive is given after increased passage of time. This repetitive action-reward combination makes the specific behavior a habit.(Robert, 1995) This theory is promoted by many famous behavioral psychologists such as B.F.Skinner and emphasizes that if actions are positively received, people are more likely to carry them on again and again while if they are negatively received, people avoid carrying out those acts/behaviors again. Incentive theory differentiates itself from other theories such as drive theory in terms of behaviorism in such a way that it involves positive reinforcement i.e the act is reinforced to make the person happy and encourage him to carry it on again for example a person knows that eating food or drinking water will make him satisfied and happy, while in the drive theory, use of negative reinforcement is made i.e the stimulus has been associated with the removal of the punishment for example a person knows that when he will consume food if he is hungry, it will eliminate the negative feeling of hunger.(Wilson,1992) In simpler words, incentive theory suggests that people are motivated to do things because of external rewards. Behavioral concepts such as association and reinforcement play an important role in this theory of motivation.(Wilson, 1992) Drive reduction theory: This theory emphasizes that people have certain biological needs or drives (example hunger, sleep and sex) and as the time passes, the strength of the desire increases if it is not fulfilled or satisfied. Upon satisfying the drive, the strength is reduced and the organism returns to a state of homeostasis. In simpler words, people are motivated to carry out some actions in order to reduce the internal tension caused by unmet needs. An example of application of this theory is that when you drink a glass of water to reduce the internal state of thirst. Another example is if we were hot, we would seek for a shade, this seeking for shade and drinking glass of water is an example of drive reducing behavior. The problem however, faced with this theory is that the drives are not always, purely motivated by physiological needs. For example, a person may smell freshly baked bread and want to eat it although he has already done his breakfast little time ago. In this case the drive hunger is not motivating him to do this action but he is just eating the bread because he is attracted to the smell and he knows that a freshly baked bread tastes very good.(Lepper, 1995) Maslows theory of hierarchy of motives: Maslow emphasized that once our basic needs, which ensure our survival are met, our attention is diverted to our relationship with others, self esteem and fulfilling personal potential. (Maslow, 1970) Physiological needs are the first needs (hunger, sex etc) that need to be satisfied. Safety needs are listed as second needs and these mainly mean the feelings of security that the world is a safe placefor an individual to live. Belongingness and love needs are listed as third most important need which refer to being loved by others and accepted so that the individual can also give love to others. Esteem need is the fourth most important need. This means that a person has feelings of his self esteem which can be achieved through receiving respect from other people and recognition. Self actualization refers to reaching ones own unique potential. The final need is to find a meaning in the world beyond ones self or self transcendence.(Whyte, 1980) This hierarchy of needs is drawn in a shape of pyramid with the most important need starting from the bottom: Arousal theory of motivation: This theory suggests that people carry out some specific actions in order to increase or decrease their levels of arousal. More clearly we can say, that this theory motivates us in order to maintain our arousal level at an optimum point, not below it, not higher. A clear example of application of this theory could be when the arousal levels gets below the optimum point, the person may go to watch a movie or go for a jog. This is likely to boost up his arousal level. Similarly, if the arousal level gets high, the person is likely to seek ways in which he can bring it down, i.e ways that make him relax such as meditating or reading a book.in monkeys, curiosity motivates them how to open a latch door or a window. (butler, 1954). This theory is very popular both in the field of psychology or physiology. It was originated by Lindsley. According to him, too little stimulation can cause a person to get bored while too high level of stimulation can cause anxiety, which results in sensation seeking. Such sensation seekers are more impulsive and likely to participate in risky behavior. Impulsivity refers to inability of a person to judge the consequences of a risky action he is going to perform. Such impulsive people might not be able to correctly process cognitive information.(lynam and miller, 2004) Instinct theory of motivation: In accordance with this theory, people behave in specific way because they are evolutionarily programmed to. People do not actually learn to behave like that, it is an inborn behavior. A clear example of such a behavior is the migrations that occur in animals world.(forbes,2011) William james created a list of instincts which included: Modesty love Attatchement Play Fear Anger Shyness However, the main problems faced by this theory were that it did not explain behavior, but just described. It described the effect of genetics and heresity on human behavior. Most of our behaviors are not unlearned and thus, these instincts are not likely to motivate us. According to Sigmund freud, human behavior is driven by two biological instincts: eros and thenatos, the life instinct and the death instinct respectively. The life instinct includes sexual motivation, the death instinct includes aggression motivation. He suggested that people should handle these aggressive instincts carefully and non-violently by engaging in competitive activities.(steven,2002) William mcdougal also pioneered an instinct theory, in his theory, instincts compose of three parts; perception, behavior and emotion. Humans have perceptual predisposition to focus on stimuli that are important to his goals. Humans have the drive and energy called the emotional core between perception of the goal and the movement towards it. Mcdougal listed 17 instincts including: Hunger Rejection of particular substances Curiosity Escape Pugnacity Sex Maternal/paternal instinct Gregariousness Self-assertion Submission Construction Acquisition Crying Laughter Comfort Rest Migration (steven,2002) Cognitive evaluation theory: This theory suggests that there are actually two types of motivation; intrinsic and extrinsic which correspond to two types of motivators: Intrinsic motivators; that come from actual performance of the task e.g achievement, responsibility and competence Extrinsic motivators; that come from a persons environment or controlled by others e.g pay, promotion, feedback and working conditions. Any of these could be a more power motivator for an individual.(Lepper,1995) Intrinsically motivated people perform mainly for their own satisfaction and achievement.if they start to believe that they are working for pay or work conditions or for any other extrinsic reason, they begin to lose motivation. It emphasizes that powerful extrinsic motivators can decrease a persons intrinsic motivation, especially if the extrinsic motivators are believed to be controlled by others by the individual.(Lepper, 1995) Hezbergs two factor theory: According to hezberg, two kinds of factors are likely to affect motivation, and they do it in different ways: Hygiene factors: if these are absent, an individual is motivated. However, their presence has no perceived effect. These are the things that when u take away from a person, he gets dissatisfied and tries to take them back. Examples include decent working conditions, pay, security, company policies and interpersonal relationships. Motivators: these are factors whose presence motivates. Their absence does not cause dissatisfaction but just fails to motivate people. We can say that hygiene factors cause dissatisfaction while motivators cause satisfaction. The two scales are independent and one can be high on either or both.(Piers, 2007) MEASUREMENT OF MOTIVATION Measurement of motivation can be classified into two types: Measurement of social drives Measurement of biological drives (Chavajay, 2002) Measurement of social drives can be done through the following ways: Personality questionnaire Projective techniques Situational tests Observation Interviews 1-personaity questionnaire: in these questionnares, subjects are asked as to how will they respond to certain situations or conditions. Various tests are used in these questionnares such as interest inventory, Minnesota multiphase personality inventory and California psychological inventory. (Chavajay,2002) 2-projective techniques: these present simple and ambiguous stimuli that allow the subject to respond with projection of both sexes in their personality. These tests are conducted by showing abstract pictures, writing stories to subjects and include other tests like Rorschach inkblot test and Thematic Apperception Test. Psychologists have experienced that these tests can provide valuable insight into ones personality. However, it is easy to misinterpret the responses and an inexperienced tester can misuse the information that is collected. Projective tests are also known as objective tests. 3-situational tests: social drive or affiliation can be measured by giving a person choice between waiting in a need to achieve or the need to affiliate with others such as drives for works, compliance drives, social approval drives, self actualization drives. 4-observation: observation can be defined as watching an individuals behavior over a period of time. It can be done in natural environment or in clinical settings. Through observation, psychologists also try to know about behavioral problems. 5-interviews: its a way to gather information face to face from the person who is being evaluated. A successive interview is that in which the interviewee is made to talk openly about his feelings, drives and experiences.(Chavajay,2002) Measurement of biological drives can be done through following ways: Speed of learning of individual Preferences shown by an individual when given choices between more than one goal Rate of response of an individual Amount of obstruction required to prevent the animal from reaching a goal Action of nervous system Amplitude of a response Gross motor activity of an individual The stimuli presented can be varied and can be internal or external. (Chavajay, 2002) LISTS OF PRIMARY AND SECONDARY MOTIVES Primary motives are also known as biological moitves have a definite physiological basis and are biologically important for an individuals survival. These arouse the behavior of an organism in directions that lead to a change in the internal environment. Sources of biological motivational needs include increase/decrease simulation, activate senses, decrease hunger, thirst, discomfort and maintaining homeostasis, balance. (Harter, 2011) The primary motives consist of: Hunger Thirst Pain Sexual drive Air or need for respiration Fatigue Sleep Maternal drive Secondary motives are individualistic in nature as they are related to self esteem, self exhibition, self security, self freedom and self assertion. These are also known as psychological motives and are very important in the development of an individuals behavior and personality.(Harter, 2011) The secondary motives include: Need for affiliation Need for approval Need for achievement Need for security Curiosity motive Competence motive Power motive Aggression motive Self actualization (Harter, 2011)

Anger by Gender

Popular stereotypes typically do not associate females with the direct expression of anger. Brody and Hall ( 1993) reviewed research on gender and emotion and found that people very clearly see females as more expressive than males when it comes to many emotions, but not in regard to anger, which was associated with males.They cite studies that indicate the consistency of such beliefs; people from various socioeconomic and age backgrounds share the belief that anger is expressed more often and more intensely by males. Cultural norms encourage or at least allow males to respond angrily when provoked; cultural defmitions of femininity make it difficult for females to be openly hostile or angry. If women fail to restrain their anger, they tend to be viewed as emotional or hysterical (Buss, 2001).These assumptions are reflected in the research literature, which focuses primarily on male-to-male or male-to-female hostility and aggression, rather than hostility and aggression on the part o f females directed at either at men or other women.This double standard is beginning to erode. Some observers believe that women can be more aggressive and assertive today, although they are still subject to more limits than men (Averill, 1992).Francesca Cancian and Steven Gordon (1988) document a normative shift in the twentieth century, which actually encourages women today to express emotions such as anger. Their research linked marital emotion norms to political and cultural events and found that in periods of social upheaval, women are encouraged to be more open with their anger.Research presents mixed findings in regard to gender and various measures of anger and hostility.For self-reported hostility, paper-and-pencil measures such as the Buss-Durkee Hostility Inventory have not revealed sex differences. Barefoot. et al. ( 1991), using a large national sample, found that men outscored women on cynical hostility regardless of age. James Check and Neil Malamuth ( 1985) assessed hostility in Canadian women and men and found that the men's average score was slightly higher than the women's (8.79 versus 7.57).When men and women were asked to keep track of specific anger experiences, Campbell ( 1993) found no significant differences in the frequency of such experiences: over a oneweek period, men reported that they became angry between six and seven times, and women between five and six times. (Buss, 2001)Tavris ( 1989) examined sex differences in anger and found no differences in how anger is experienced, how it is expressed, how well it is identified, or what categories of things arouse anger. She believes, however, that although women do not feel anger any less strongly than men, they are less likely to express it because of the costs associated with their lower social status.Tavris points out that men and women become angry about the same categories of offenses, such as condescending treatment, injustice, and attacks on self-esteem, but they often disagree about what they consider to be condescending treatment, injustice, or attack.Frodi and Macaulay ( 1977) found that both women and men were angered by condescending treatment: women regardless of the provoker's sex and men by a superior attitude on the part of a female. Men were more angered than women by physical and verbal aggression on the part of another male.Brody and Hall ( 1993) reviewed studies showing that there are fairly clearcut differences in regard to positive emotions (with women experiencing and expressing them more), but in regard to negative emotions, especially anger, the findings are less consistent. Females were more likely to feel and express â€Å"intropunitive† emotions (such as shame, sadness, and guilt), and men were more likely to feel and express â€Å"outward directed† emotions (such as contempt).However, for anger, differences between the sexes are often very small or males are more angry than females. Kopper and Epperson (1991) looked at the relationship between sex and sex role identity on anger expression and found sex not to be an important factor in the expression or suppression of anger (however, sex role identity was).Some research finds more anger on the part of females. The review article by Brody and Hall ( 1993) cites research by Brody that found more anger on the part of women toward imaginary male protagonists.Mirowsky and Ross ( 1995) investigated whether women's greater distress accounts are a function of women's greater expressiveness (they are not) or whether they truly experience more distress (they do). In the process of their work they found that females experience various feelings, including anger, more often than males.Reiser ( 1994) explored respondents' feelings of anger toward the other sex using a random sample of North Carolina residents and found a significant sex difference, with female respondents reporting greater anger than male respondents. Conger et al. (1993, cited by Miroswky and R oss 1995) surveyed 451 married couples who lived in the rural Midwest and found that the women reported significantly greater levels of marital hostility than the men.

Houston †How to Talk to a Hunter Essay

Through her How to Talk to a Hunter short story, author Pam Houston uses the second-person point of view to describe a rather controversial relationship between a certain liberal woman and a conservative man. The author thus explores the dynamics of gender relations through this unconventional and subtle approach. By employing this unusual point of view, the author seeks to involve all her readers in the story’s happenings. Further it is notable that Houston dwells on a rather sensitive topic of gender relations. Usually conservative societies seek to unjustly subordinate women to male power. The author thus deems it fit to make use of the second-person point of view to inform readers of, not what the story’s characters are experiencing, but rather, to explore the readers’ thoughts and feelings. This approach accommodates a great variety of readers into the story’s plot by entertaining persistent ambiguity that leaves the interpretation of the narrative’s theme open to audience speculation. To illustrate, by describing the reaction that the hunter will have towards the lady in the second-person, the author avoids being unnecessarily antagonistic in the story’s development (Houston 12). Instead, Houston allows readers to, firstly, examine their sentiments towards the story’s happenings and secondly, to identify with the some of the story’s happenings. In effect, the author leads the reader in developing the story’s plot as opposed to unilaterally telling the story by herself. In addition, this second-person point of view enables the author to avoid taking sides with regard to the gender debate. Rather, Houston incorporates both gender in analyzing and critiquing the existing gender relations. This technique thus makes the literary work acceptable to a wide variety of people from both the female and male gender. Houston capitalizes on the ability to arouse readers’ feelings as she seeks both female and male acceptance, and identification with, her How to Talk to a Hunter story.

The Healing Power Of Music - 1612 Words

The Healing Power of Music The Alzheimer’s Foundation of America, defines Alzheimer’s as being the most common form of dementia, occurring in 60% to 80% of people suffering from symptoms of dementia (Clair Tomaino, 2016). The foundation also states that it is an irreversible disease that progresses over time, destroying cognitive functions such as: memory, learning, and language skills. Furthermore it may alter behaviors and mood, cause disorientation, as well as agitation (Clair Tomaino, 2016; Witzke, Rhone, Backhaus, Shaver, 2008, p. 46). Those percentages are quite large, and they are only going to keep rising. How can those of us in the medical field, and out of the field attempt to repair or slow down the effects of this disease? What options do we have at our disposal? Interventions that can be used to assist in relieving symptoms are animal-assisted therapy (AAS), music therapy, and light therapy as well as massage (Witzke, Rhone, Backhaus, Shaver, 200 8, p. 46). Although Witzke, Rhone, Backhaus, Shaver (2008) state that in Japan music therapy is preferred as opposed to animal assisted therapy for dementia and Alzheimer patients due to the fact that they have had issues trying to control the breeding as well as control infection. They also recorded that there is the possibility of a patient not liking animals or having an allergy to the animal. Music has the ability to bring us back in time and recreate a memory just from hearing a few cords of aShow MoreRelatedThe Healing Power Of Music1863 Words   |  8 PagesThe Healing Power Of Music Music has survived throughout the course of human history because it has always been such a huge part of the human life. Music allows us to feel joy, sadness and fear. It can bring us pleasure, express what we cannot express in words. In fact, no matter what culture, race, or ethnicity you will find music is always present and contains an important role in society. 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Key Pieces of Film Studies Essay Topics

Key Pieces of Film Studies Essay Topics Film Studies Essay Topics Explained One of the greatest approaches to select your topic is to find one which you get a strong opinion about. Your specific ideas and opinions in the paper has to be supported with arguments. Last word of advice is to seek advice from your teacher before the last decision about this issue selection for argumentative essays. You will have to back up your viewpoint with well-researched facts and data also. The Key to Successful Film Studies Essay Topics The difference is in the intellectual capabilities connected with the age of students, and their levels of exposure. In the modern society, gender means a whole lot more than it used to. You should have your reasons, and our primary concern is that you find yourself getting a great grade. Discover how studies utilize a complicated research library. Whispered Film Studies Essay Topics Secrets Like the custom of oncology nursing, it's an emotionally in add ition to professionally demanding experience. The student may give the particulars of the topics to the firm. So should you need help with any writing task, don't hesitate to get in touch with our expert services. If you are searching for assistance with your essay then we provide a comprehensive writing service given by fully qualified academics in your area of study. By way of example, in college, you might be requested to compose a paper from the opposing standpoint. A review of each major point and concluding thoughts utilizing a rate system, dependent on numbers, will certainly help your film studies paper stick out. The character of the issue selected is important in picking the correct strategy. You might think about history for a branch of study that falls away from the realm of social studies. The distinctive writing assignment suggests that you've studied a variety of films, technical facets, and theories. In reality, a film studies writing assignment provides the chance for an assortment of thoughts and topics. The reality is that a film study writing assignment provides the chance for assorted thoughts and themes. Specifically, you're going to be expected to take thorough notes to analyse the exceptional manners of filming, together with videography. Academic Sciences writers can direct you on each step of the procedure to make certain that you understand how to compose a film studies essay. Most students enjoy watching movies for a number of unique factors. Creating a preliminary structure for the essay before you've finished collecting information is the most helpful. Showing awareness about recent changes in this issue you're writing on is very important to win an excellent grade. You will have to figure out the kind of essay you're going to be writing and which of the aforementioned analytical elements you will include. Apart from that, it also needs to be known that essay is only a wide category and within this, there are several kinds of essays and every one of them have another type of pattern. The very best argumentative essay writing service on the net is an organization that supplies good quality and very affordable help on argumentative essay and argumentative essay topics. Argumentative essay topics cover a w ide selection of subjects, and can be quite persuasive if an excellent essay represents them. Occasionally, selecting an excellent argumentative essay topics will be quite tough. There are several interesting and challenging Shakespeare essay topics to pick from. Therefore, either you wish to learn more about how to compose an essay, or you desire some essay writing services or even in the event that you would like to go through some sample essays, then just refer to WritingBest and all of your requirements will be fulfilled once possible. Both principal kinds are the crucial essay and the theoretical essay. Choosing great essay topics for middle school must be a careful procedure, where a balance must be struck between topics that could be too simplistic, more proper for the main school, and choosing argumentative essay topics that can be too complicated or controversial. Following are a few of the advised sociology essay topic for those students that are unable to decide on a great topic for their assignment.

Similarities and Differences between Gilgamesha dn Enkindu

Similarities and Differences between Gilgamesh and Enkindu The Myth known today as the epic of Gilgamesh was considered in ancient times to be one of the great masterpieces of cuneiform literature.The tale revolves around a legendary hero named Gilgamesh, who was known said to be the king of the Sumerian city of uruk.Gilgamesh was known to have supernatural abilities and be half human and half god similar to his best friend who was later known known as Enkindu.This person was also blessed with supernatural abilities and was half human-half animal.Gilgamesh and Enkindu both have similar traits such as they both use love as a motivating force and they both clearly are half human-half supernatural.They also have differences such†¦show more content†¦Then on page 21 Enkindu stood watch for the shepherds against the lions so that the shepherds could get a good night sleep, this protects the shepherds and feeds them. This shows the power that Enkindu has by fighting of lions, capturing wolves and keeping the shepherds safe. So basically G ilgamesh who is half human and half God, he thinks he is the most powerful person on this Earth and thinks he can do whatever he wants whenever he wants. He takes every woman there is, even the ones that are getting married. Since he is very ignorant and doesn’t care about his people, the people complained to the Gods who then create a double of Gilgamesh who is called Enkindu, who was just as smart and strong as Gilgamesh. Gilgamesh and Enkidu also had differences it seemed that they had their own journey within each other’s journey. Enkidu’s journey starts of when the prostitutes were order by Gilgamesh to go and get Enkidu. This is because Enkidu saves his former animal friends from cages. This to me to is the starting point of Enkidu journey towards Gilgamesh. This journey was mentored by the prostitute who was also the tempter. As Enkidu finds his way to Gilgamesh this starts a whole new journey.This journey was shortlived because later on as the story goes on Gilgamesh and enkindu goes on and kills both humbaba and the bull of heaven,which the godess Ishtar sends to punish Gilgamesh for spurring her advances.As a punishment for these actions,the gods sentence Enkindu

Internal Combustion Engines Essay Summary Example For Students

Internal Combustion Engines Essay Summary Internal Combustion EnginesIntroductionInternal Combustion Engine, a heat engine in which the fuel is burned (that is, united with oxygen ) within the confining space of the engine itself. This burning process releases large amounts of energy, which are transformedinto work through the mechanism of the engine. This type of engine differentfrom the steam engine, which process with an external combustion engine thatfuel burned apart from the engine. The principal types of internal combustionengine are : reciprocating engine such as Otto-engine, and Diesel engines ; androtary engines, such as the Wankel engine and the Gas-turbine engine. In general, the internal combustion engine has become the means ofpropulsion in the transportation field, with the exception of large shipsrequiring over 4,000 shaft horsepower ( hp). In stationary applications, size of unit and local factor oftendetermine the choice between the use of steam and diesel engine. Diesel powerplants have a distinct economic advantage over steam engine when size of theplant is under about 1,000 hp. However there are many diesel engine plants muchlarge than this. Internal combustion engines are particularly appropriate forseasonal industries, because of the small standby losses with these enginesduring the shutdown period. HistoryThe first experimental internal combustion engine was made by a Dutchastronomer, Christian Huygens, who, in 1680, applied a principle advanced byJean de Hautefeuille in 1678 for drawing water. This principle was based on thefact that the explosion of a small amount of gunpowder in a closed chamberprovided with escape valves would create a vacuum when the gases of combustioncooled. Huygens, using a cylinder containing a piston, was able to move it inthis manner by the external atmospheric pressure. The first commercially practical internal combustion engine was built bya French engineer, ( Jean Joseph ) Etienne Lenoir, about 1859-1860. It usedilluminating gas as fuel. Two years later, Alphonse Beau de Rochas enunciatedthe principles of the four-stroke cycle, but Nickolaus August Otto built thefirst successful engine ( 1876 ) operating on this principle. Reciprocating EngineComponents of EnginesThe essential parts of Otto-cycle and diesel engines are the same. Thecombustion chamber consists of a cylinder, usually fixed, which is closed at oneend and in which a close-fitting piston slides. The in-and-out motion of thepiston varies the volume of the chamber between the inner face of the piston andthe closed end of the cylinder. The outer face of the piston is attached to acrankshaft by a connecting rod. The crankshaft transforms the reciprocatingmotion of the piston into rotary motion. In multi-cylindered engines thecrankshaft has one offset portion, called a crankpin, for each connecting rod,so that the power from each cylinder is applied to the crankshaft at theappropriate point in its rotation. Crankshafts have heavy flywheels andcounterweights, which by their inertia minimize irregularity in the motion ofthe shaft. An engine may have from 1 to as many as 28 cylinders. The fuel supply system of an internal-combustion engine consists of atank, a fuel pump, and a device for vaporizing or atomizing the liquid fuel. InOtto-cycle engines this device is a carburetor. The vaporized fuel in mostmulti-cylindered engines is conveyed to the cylinders through a branched pipecalled the intake manifold and, in many engines, a similar exhaust manifold isprovided to carry off the gases produced by combustion. The fuel is admitted toeach cylinder and the waste gases exhausted through mechanically operated poppetvalves or sleeve valves. The valves are normally held closed by the pressure ofsprings and are opened at the proper time during the operating cycle by cams ona rotating camshaft that is geared to the crankshaft . By the 1980s moresophisticated fuel-injection systems, also used in diesel engines, had largelyreplaced this traditional method of supplying the proper mix of air and fuel;computer-controlled monitoring systems improved fuel economy and reducedpollu tion. IgnitionIn all engines some means of igniting the fuel in the cylinder must beprovided. For example, the ignition system of Otto-cycle engines , the mixtureof air and gasoline vapor delivered to the cylinder from the carburetor and nextoperation is that of igniting the charge by causing a spark to jump the gapbetween the electrodes of a spark plug, which projects through the walls of thecylinder. One electrode is insulated by porcelain or mica; the other is groundedthrough the metal of the plug, and both form the part of the secondary circuitof an induction system. The principal type of high-tension ignition now commonly used is thebattery-and-coil system. The current from the battery flows through the low-tension coil and magnetizes the iron core. When this circuit is opened at thedistributor points by the interrupter cam, a transient high-frequency current isproduced in the primary coil with the assistance of the condenser. This inducesa transient, high-frequency, high-voltage current in the secondary winding. Thissecondary high voltage is needed to cause the spark to jump the gap in the sparkplug. The spark is directed to the proper cylinder to be fired by thedistributor, which connects the secondary coil to the spark plugs in the severalcylinders in their proper firing sequence. The interrupter cam and distributorare driven from the same shaft, the number of breaking points on the interruptercam being the same as the number of cylinders. Cooling SystemBecause of the heat of combustion, all engines must be equipped withsome type of cooling system. Some aircraft and automobile engines, smallstationary engines, and outboard motors for boats are cooled by air. In thissystem the outside surfaces of the cylinder are shaped in a series of radiatingfins with a large area of metal to radiate heat from the cylinder. Other enginesare water-cooled and have their cylinders enclosed in an external water jacket. In automobiles, water is circulated through the jacket by means of a water pumpand cooled by passing through the finned coils of a radiator. Some automobileengines are also air-cooled, and in marine engines sea water is used for cooling. Christopher Columbus EssayThe exhaust gases are then expelled through an exhaust port through the actionof the turning rotor. The cycle takes place alternately at each face of therotor, giving three power strokes for each turn of the rotor. The Wankelengines compact size and consequent lesser weight as compared with the pistonengine gave it increasing value and importance with the rise in gasoline pricesof the 1970s and 80s. In addition, it offers practically vibration-freeoperation, and its mechanical simplicity provides low manufacturing costs. Cooling requirement s are low, and its low center of gravity contributes todriving safety. Gas TurbineAlso called as combustion turbine, engine that employs gas flow as theworking medium by which heat energy is transformed into mechanical energy. Gasis produced in the engine by the combustion of certain fuels. Stationary nozzlesdischarge jets of this gas against the blades of a turbine wheel. The impulseforce of the jets causes the shaft to turn. A simple-cycle gas turbine includesa compressor that pumps compressed air into a combustion chamber. Fuel ingaseous or liquid-spray form is also injected into this chamber, and combustiontakes place there. The combustion products pass from the chamber through thenozzles to the turbine wheel. The spinning wheel drives the compressor and theexternal load, such as an electrical generator. In a turbine or compressor, a row of fixed blades and a correspondingrow of moving blades attached to a rotor is called a stage. Large machinesemploy multistage axial-flow compressors and turbines. In multi-shaftarrangements, the initial turbine stage (or stages) powers the compressor on oneshaft while the later turbine stage (or stages) powers the external load on aseparate shaft. The efficiency of the gas-turbine cycle is limited by the need forcontinuous operation at high temperatures in the combustion chamber and earlyturbine stages. A small, simple-cycle gas turbine may have a relatively lowthermodynamic efficiency, comparable to a conventional gasoline engine. Advancesin heat-resistant materials, protective coatings, and cooling arrangements havemade possible large units with simple-cycle efficiencies of 34 percent or higher. The efficiency of gas-turbine cycles can be enhanced by the use ofauxiliary equipment such as inter-coolers, regenerators, and reheaters. Thesedevices are expensive, however, and economic considerations usually precludetheir use. In a combined-cycle power plant, the considerable heat remaining in thegas turbine exhaust is directed to a boiler called a heat-recovery steamgenerator. The heat so recovered is used to raise steam for an associated steamturbine. The combined output is approximately 50 percent greater than that ofthe gas turbine alone. Combined cycles with thermal efficiency of 52 percent andhigher are being put into service. Gas turbines have been applied to thepropulsion of ships and railroad locomotives. A modified form of gas turbine,the turbojet, is used for airplane propulsion. Heavy-duty gas turbines in bothsimple and combined cycles have become important for large-scale generation ofelectricity. Unit ratings in excess of 200 megawatts (MW) are available. Thecombined-cycle output can exceed 300 MW. The usual fuels used in gas turbines are natural gas and liquids such askerosene and diesel oil. Coal can be used after conversion to gas in a separategasifier. Internal-Combustion Engines and Air PollutionAir pollution from automobile engines ( smog ) was first detected about1942 in Los Angeles, CA. Smog arises from sunlight-induced photochemicalreactions between nitrogen dioxide and the several hundred hydrocarbons in theatmosphere. Undesirable products of the reactions include ozone, aldehydes, andperoxyacylnitrates ( PAN ). These are highly oxidizing in nature and cause eyeand throat irritation. Visibility-decreasing nitrogen dioxide and aerosols arealso formed. Five categories of air pollutants and percent contribution from alltransportation source and the highway vehicle subset are show in Table -1. Virtually all of the transportation CO, about half the hydrocarbons, and aboutone-third of the nitrogen oxides come from gasoline engines. Diesel enginesaccount for the particulate. Emissions from internal-combustion engines include those from blowby,evaporation, and exhaust. These can vary considerably in amount and compositiondepending on engine type, design, and condition, fuel-system type, fuelvolatility, and engine operating point. For an automobile without emissioncontrol it is estimated that of the hydrocarbon emission, 20 to 25 percent arisefrom blowby, 60 percent from the exhaust, and the balance from evaporativelosses primarily from the fuel tank and to a lesser extent from the carburetor. All other non-hydrocarbon emissions emanate from the exhaust. At least 200 hydrocarbon (HC) compounds have been identified in exhaust. Some such as the olefin compounds react products. These are termed reactivehydrocarbons. Others such as the paraffin are virtually unreactive. Special DevelopmentsThe Stratified-Charge Engine a modification of the conventional spark-ignition piston engine, the stratified charge engine is designed to reduceemissions without the need for an exhaust-gas recirculation system or catalyticconverter. Its key feature is a dual combustion chamber for each cylinder, witha prechamber that receives a rich fuel-air mixture while the main chamber ischarged with a very lean mixture. The spark ignites the rich mixture that inturn ignites the lean main mixture. The resulting peak temperature is low enoughto inhibit the formation of nitrogen oxides, and the mean temperature issufficiently high to limit emissions of carbon monoxide and hydrocarbon. Two rather distinct means for accomplishing the stratified chargecondition are under consideration :1. A single combustion chamber with a well-controlled rotating airmotion. This arrangement is illustrated (Fig.6) by the Texaco Combustion Process(TCP), patented in 1949. 2. A prechamber or two-chamber system. This is illustrated by Fig.7,which shows the general arrangement of the Honda Compound-vortex controlled-combustion (CVCC) system. For both systems, very careful development has proved to be necessary toobtain complete combustion of the fuel under the wide range of speed and loadconditions required of an automotive engine. English