Lifestyle Incongruence :: Economy, Minorities, Poverty

The situation that places African-Americans along with other minorities at an economic disadvantage because blacks tend to earn less than whites which often force blacks to pick between paying rent or providing food to make it daily. The hierarchy of needs are not being meet psychologically is a stressor that can produce health related illness that can effect a community as a whole if no intervention are made. (16) In exploring the impact that cultural model on the African-American community, William Dressler and James Bindon case study entitled, â€Å"The Health consequence of cultural consonance; cultural dimension of lifestyle, social support and arterial blood pressure in an African American community. â€Å" In the case study, Dressler and Bindon focus on the areas of society, culture and individual health; cultural models, cultural consonance and cultural consonance; and blood pressure in the African American community. The first goal of this research involves determining if there are shared models of lifestyle and social support in the community. Two, determine what the separate associations of cultural consonance in lifestyle and cultural consonance in social support are with blood pressure. Lastly, determine if there is a synergism between cultural consonance in social support in relations to stress (blood pressure). In society, culture and individual health, Dressler and Bindon noted that, socioeconomic status refers to the position of the individual in a system of ranked status based on criteria that include occupation, income and education. (9). Social integration refers to the degree to which individuals report social connections based on marital status, membership in voluntary associations, and interaction with friends and relative. (10) In return, a lower ranking on socioeconomic status is associated with an increase risk of disease. Higher levels of social integration are associated with a reduced risk of disease. (11) Furthermore, being lower in the status hierarchy, or being socially, isolated, could conceivably be associated with a wide variety of factors from not getting a sufficient amount of exercise to perceptions of stress on a daily basis. (12) Perspective epidemiological research designs are fairly efficient at ruling out alternative explanations by taking into account (or controlling for) exposure to other kinds of risks. (13) Thus, numerous studies have shown that the risk of disease associated with status role positions remains unaffected by controlling for pre-existing health problems, obesity access to medical care, dietary patterns, smoking; drinking and similar sorts of factors known to have effects on health.

Proud to Be an Indian Essay

India, a country with a culture having more than ten thousand years has enriched the global scientific, educational, economic and cultural scenario significantly. That is the reason why mark Twain has stated â€Å"India is the cradle of the human race, the birthplace of human speech, the mother of history, the grandmother of legend and the great grandmother of tradition.† Being born in such a great country, you have millions of reasons to feel proud as an Indian. Some of them are : 1 .Indian culture is the best in the world The very word culture started from the country India. When the people of today’s developed nations were wandering like nomadic, Indians built Harappa and Mohenjo-Daro, the first ever planned city of the world. India is the home to four major religions of the world. The first epic of the world was written in India. Sanskrit, according to a major group of linguistics is considered as the mother of all European languages. Forbes magazine has rated Sanskrit as the most suitable language for software applications. 2. First university of the world was established in Takshila(in Modern Bihar) in the year 700BC. More than 60 subjects were taught here to near about 10,500 students who came from different parts of the world. 3. We have never invaded any country in the entire history of 5000 years. Rather, Buddha and Gandhi taught the world the power of non-violence and truth. Recently, American president Barak Obama has openly admitted that Gandhi is an ideal for him. 4. Till 1896, India was the only known source of diamond in the world. Tremendous wealth of India attracted several invaders and traders. Till the invasion of British East India Company, India was the richest country of the world. 5. Number system is the greatest contribution of India to science in general and mathematics in particular. Indian Mathematician Aryabhatta invented zero. Bhaskaracharya, in fifth century, calculated the time taken by earth to rotate around sun exactly. Budhayana calculated the value of pi. Algebra, trigonometry and calculus had their origin India during sixth century. 6. Ayurveda, the earliest school of medicine has its origin in India. Surgery was done for the first time India by Sushruta 2600 years back. 7. India taught the art of navigation to the world on River Sind 6000 years back. Proof to it is the derivation of the very word navigation from NAVGATIH (a Sanskrit word). 8. Just like Indian culture and lifestyle of India , Indian Food has also been influenced by various civilizations and Regional Cultures. Traditional Indian food is not only famous worldwide for its spicy and lip-smacking taste, but also popular for its importance in the direction of maintaining a healthy life style. Indian food is both delicious and good for health. It matches to the requirements and taste of both vegetarians and non-vegetarians. Indians like hot, fresh and nutritious food in their daily diet. However, each part of India has its own unique cuisine and way of preparing recipes. In North India, Roti is proffered over rice. Use of cheese, curd, milk and vegetables in preparing different dishes is primarily marked in North-India. Tandoori is one of the most important dishes of North India which has a pan -Indian acceptance. Use of oil in preparing tandoori is minimal and only selected Indian spices are added while preparing any tandoori recipe. In south India, use of tamarind and pepper while preparing recipes is common. Here, people prefer to eat rice over Roti. Use of coconut oil in preparing dishes is marked in several south Indian states. Dosa is one of the most popular South Indian foods that have a pan-Indian appeal. In eastern part of India, people are generally fond of rice and fish. This is due to the availability of fish in abundance. Fish recipes of several types are vital aspects of East Indian food. In the western-part of India, spicy food is the first preference of people. Here also you can mark dominance of cheese while preparing dishes. Both rice and roti are popular in western India. 9. Family is the longest surviving institution of India irrespective of the ages, transformations, religious and political views compared to any other country and it shows how rich is our Indian culture. 10. I am proud to be Indian because of our country’s achievements in space and missile technology. India has launched a number of satellites in space for helping us in weather forecast, communications, medical research, and education. The missiles such as Agni, Prithvi strengthened our nation’s security and ensured a place in the elite group of the world’s powerful countries. Moreover, our scientists have lifted India’s pride by placing our Tri-colour on the moon and are now looking for landing in the planet Mars. 11. India is a country where people respect elders live in peace and harmony. India is the only country where there are people of different languages, religions and race, but all of them live together in harmony. There are 22 official languages a nd over 1600 dialects spoken. Nearly 650 different recognised tribes reside across the country. 12. India is the largest democracy in the world. It has a civilisation that is more than 5000 years old and boasts of multiple cultural origins. There is an emerging global, scientific and technological superpower. 13. It is a land of holy rivers like Ganga, Yamuna, Brahmaputra, Cauvery,Mahanadi etc and beautiful mountains spread densely in north and eastern india and dense forests scattered all over india . We find many seas in the South of India. There is natural beauty in our country. 14. My country with its rich heritage and tradition I say is the most beautiful nation. We are also recognised for being the world’s second largest in population. But unity in diversity is the main reason for my pride in being an Indian. We have different languages, different cultures, food, clothes, and traditions and yet we stand united. Non violence, democracy, intelligence based on our high standards of education, our natural wealth, harmony, festivals, family, system, caring for the aged, service and sacrifice are some of the things that I am proud of our land. 15. Among the finest institutions this country has produced are the Indian Armed Forces. It is the world’s third largest standing army comprising over 1.1 million men in uniform. 16. I am proud also of the education provided by the Indian Institutes of Technology (IITs) and the Indian Institutes of Managements (IIMs) which can boast of standards equal to the best in the world at far less cost. Products of these institutions now head global organizations and play a major role in organizations like NASA. Indians are familiar as doctors and scientists in many developed countries. 17. We Indians are the wealthiest among all ethnic groups in America , even faring better than the whites and the natives. There are 3.22 millions of Indians in USA (1.5% of population). YET, 38% of doctors in USA are Indians. 12% scientists in USA are Indians. 36% of NASA scientists are Indians. 34% of Microsoft employees are Indians. 28% of IBM employees are Indians. 17% of INTEL scientists are Indians. 13% of XEROX employees are! Indians. 18. Chess and Hockey was invented in India. I have got tons of reasons to love my country, but the most important thing is I love my country and I need no reason for it. Jai Hind! I am proud to be an Indian !

Synchronous Motor

Chapter (11) Synchronous Motors Introduction It may be recalled that a d. c. generator can be run as a d. c. motor. In like manner, an alternator may operate as a motor by connecting its armature winding to a 3-phase supply. It is then called a synchronous motor. As the name implies, a synchronous motor runs at synchronous speed (Ns = 120f/P) i. e. , in synchronism with the revolving field produced by the 3-phase supply. The speed of rotation is, therefore, tied to the frequency of the source.Since the frequency is fixed, the motor speed stays constant irrespective of the load or voltage of 3phase supply. However, synchronous motors are not used so much because they run at constant speed (i. e. , synchronous speed) but because they possess other unique electrical properties. In this chapter, we shall discuss the working and characteristics of synchronous motors. 11. 1 Construction A synchronous motor is a machine that operates at synchronous speed and converts electrical energy into mechanical energy. It is fundamentally an alternator operated as a motor.Like an alternator, a synchronous motor has the following two parts: (i) a stator which houses 3-phase armature winding in the slots of the stator core and receives power from a 3-phase supply [See (Fig. (11. 1)]. (ii) a rotor that has a set of salient poles excited by direct current to form alternate N and S poles. The exciting coils are connected in series to two slip rings and direct current is fed into the winding from an external exciter mounted on the rotor shaft. The stator is wound for the same number of poles as the rotor poles.As in the case of an induction motor, the number of poles determines the synchronous speed of the motor: Fig. (11. 1) 293 Synchronous speed, N s = where 120f P f = frequency of supply in Hz P = number of poles An important drawback of a synchronous motor is that it is not self-starting and auxiliary means have to be used for starting it. 11. 2 Some Facts about Synchronous Motor Some salient features of a synchronous motor are: (i) A synchronous motor runs at synchronous speed or not at all. Its speed is constant (synchronous speed) at all loads. The only way to change its speed is to alter the supply frequency (Ns = 120 f/P). ii) The outstanding characteristic of a synchronous motor is that it can be made to operate over a wide range of power factors (lagging, unity or leading) by adjustment of its field excitation. Therefore, a synchronous motor can be made to carry the mechanical load at constant speed and at the same time improve the power factor of the system. (iii) Synchronous motors are generally of the salient pole type. (iv) A synchronous motor is not self-starting and an auxiliary means has to be used for starting it. We use either induction motor principle or a separate starting motor for this purpose.If the latter method is used, the machine must be run up to synchronous speed and synchronized as an alternator. 11. 3 Operating Principle The fact that a synchronous motor has no starting torque can be easily explained. (i) Consider a 3-phase synchronous motor having two rotor poles NR and SR. Then the stator will also be wound for two poles NS and SS. The motor has direct voltage applied to the rotor winding and a 3-phase voltage applied to the stator winding. The stator winding produces a rotating field which revolves round the stator at synchronous speed Ns(= 120 f/P).The direct (or zero frequency) current sets up a two-pole field which is stationary so long as the rotor is not turning. Thus, we have a situation in which there exists a pair of revolving armature poles (i. e. , NS ? SS) and a pair of stationary rotor poles (i. e. , NR ? SR). (ii) Suppose at any instant, the stator poles are at positions A and B as shown in Fig. (11. 2 (i)). It is clear that poles NS and NR repel each other and so do the poles SS and SR. Therefore, the rotor tends to move in the anticlockwise direction. After a period of half-cycle (or ? = 1 /100 second), the polarities of the stator poles are reversed but the polarities of the rotor poles remain the same as shown in Fig. (11. 2 (ii)). Now SS and NR attract 294 each other and so do NS and SR. Therefore, the rotor tends to move in the clockwise direction. Since the stator poles change their polarities rapidly, they tend to pull the rotor first in one direction and then after a period of half-cycle in the other. Due to high inertia of the rotor, the motor fails to start. Fig. (10. 2) Hence, a synchronous motor has no self-starting torque i. e. , a synchronous motor cannot start by itself.How to get continuous unidirectional torque? If the rotor poles are rotated by some external means at such a speed that they interchange their positions along with the stator poles, then the rotor will experience a continuous unidirectional torque. This can be understood from the following discussion: (i) Suppose the stator field is rotating in the clockwise direction and the rotor is als o rotated clockwise by some external means at such a speed that the rotor poles interchange their positions along with the stator poles. (ii) Suppose at any instant the stator and rotor poles are in the position shown in Fig. 11. 3 (i)). It is clear that torque on the rotor will be clockwise. After a period of half-cycle, the stator poles reverse their polarities and at the same time rotor poles also interchange their positions as shown in Fig. (11. 3 (ii)). The result is that again the torque on the rotor is clockwise. Hence a continuous unidirectional torque acts on the rotor and moves it in the clockwise direction. Under this condition, poles on the rotor always face poles of opposite polarity on the stator and a strong magnetic attraction is set up between them.This mutual attraction locks the rotor and stator together and the rotor is virtually pulled into step with the speed of revolving flux (i. e. , synchronous speed). (iii) If now the external prime mover driving the rotor is removed, the rotor will continue to rotate at synchronous speed in the clockwise direction because the rotor poles are magnetically locked up with the stator poles. It is due to 295 this magnetic interlocking between stator and rotor poles that a synchronous motor runs at the speed of revolving flux i. e. , synchronous speed. Fig. (11. 3) 11. Making Synchronous Motor Self-Starting A synchronous motor cannot start by itself. In order to make the motor self-starting, a squirrel cage winding (also called damper winding) is provided on the rotor. The damper winding consists of copper bars embedded in the pole faces of the salient poles of the rotor as shown in Fig. (11. 4). The bars are short-circuited at the ends to form in effect a partial Fig. (11. 4) squirrel cage winding. The damper winding serves to start the motor. (i) To start with, 3-phase supply is given to the stator winding while the rotor field winding is left unenergized.The rotating stator field induces currents in the damper or squirrel cage winding and the motor starts as an induction motor. (ii) As the motor approaches the synchronous speed, the rotor is excited with direct current. Now the resulting poles on the rotor face poles of opposite polarity on the stator and a strong magnetic attraction is set up between them. The rotor poles lock in with the poles of rotating flux. Consequently, the rotor revolves at the same speed as the stator field i. e. , at synchronous speed. iii) Because the bars of squirrel cage portion of the rotor now rotate at the same speed as the rotating stator field, these bars do not cut any flux and, therefore, have no induced currents in them. Hence squirrel cage portion of the rotor is, in effect, removed from the operation of the motor. 296 It may be emphasized here that due to magnetic interlocking between the stator and rotor poles, a synchronous motor can only run at synchronous speed. At any other speed, this magnetic interlocking (i. e. , rotor poles facing o pposite polarity stator poles) ceases and the average torque becomes zero.Consequently, the motor comes to a halt with a severe disturbance on the line. Note: It is important to excite the rotor with direct current at the right moment. For example, if the d. c. excitation is applied when N-pole of the stator faces Npole of the rotor, the resulting magnetic repulsion will produce a violent mechanical shock. The motor will immediately slow down and the circuit breakers will trip. In practice, starters for synchronous motors arc designed to detect the precise moment when excitation should be applied. 11. 5 Equivalent Circuit Unlike the induction motor, the synchronous motor is connected to two electrical systems; a d. . source at the rotor terminals and an a. c. system at the stator terminals. 1. Under normal conditions of synchronous motor operation, no voltage is induced in the rotor by the stator field because the rotor winding is rotating at the same speed as the stator field. Only the impressed direct current is present in the rotor winding and ohmic resistance of this winding is the only opposition to it as shown in Fig. (11. 5 (i)). 2. In the stator winding, two effects are to be considered, the effect of stator field on the stator winding and the effect of the rotor field cutting the stator conductors at synchronous speed.Fig. (11. 5) (i) The effect of stator field on the stator (or armature) conductors is accounted for by including an inductive reactance in the armature winding. This is called synchronous reactance Xs. A resistance Ra must be considered to be in series with this reactance to account for the copper losses in the stator or armature winding as shown in Fig. (11. 5 (i)). This 297 resistance combines with synchronous reactance and gives the synchronous impedance of the machine. (ii) The second effect is that a voltage is generated in the stator winding by the synchronously-revolving field of the rotor as shown in Fig. 11. 5 (i)). This generat ed e. m. f. EB is known as back e. m. f. and opposes the stator voltage V. The magnitude of Eb depends upon rotor speed and rotor flux ? per pole. Since rotor speed is constant; the value of Eb depends upon the rotor flux per pole i. e. exciting rotor current If. Fig. (11. 5 (i)) shows the schematic diagram for one phase of a star-connected synchronous motor while Fig. (11. 5 (ii)) shows its equivalent circuit. Referring to the equivalent circuit in Fig. (11. 5 (ii)). Net voltage/phase in stator winding is Er = V ? Eb Armature current/phase, I a = where 2 Zs = R 2 + X s a hasor difference Er Zs This equivalent circuit helps considerably in understanding the operation of a synchronous motor. A synchronous motor is said to be normally excited if the field excitation is such that Eb = V. If the field excitation is such that Eb < V, the motor is said to be under-excited. The motor is said to be over-excited if the field excitation is such that Eb > V. As we shall see, for both normal an d under excitation, the motor has lagging power factor. However, for over-excitation, the motor has leading power factor.Note: In a synchronous motor, the value of Xs is 10 to 100 times greater than Ra. Consequently, we can neglect Ra unless we are interested in efficiency or heating effects. 11. 6 Motor on Load In d. c. motors and induction motors, an addition of load causes the motor speed to decrease. The decrease in speed reduces the counter e. m. f. enough so that additional current is drawn from the source to carry the increased load at a reduced speed. This action cannot take place in a synchronous motor because it runs at a constant speed (i. e. , synchronous speed) at all loads.What happens when we apply mechanical load to a synchronous motor? The rotor poles fall slightly behind the stator poles while continuing to run at 298 synchronous speed. The angular displacement between stator and rotor poles (called torque angle ? ) causes the phase of back e. m. f. Eb to change w. r. t. supply voltage V. This increases the net e. m. f. Er in the stator winding. Consequently, stator current Ia ( = Er/Zs) increases to carry the load. Fig. (11. 6) The following points may be noted in synchronous motor operation: (i) A synchronous motor runs at synchronous speed at all loads.It meets the increased load not by a decrease in speed but by the relative shift between stator and rotor poles i. e. , by the adjustment of torque angle ?. (ii) If the load on the motor increases, the torque angle a also increases (i. e. , rotor poles lag behind the stator poles by a greater angle) but the motor continues to run at synchronous speed. The increase in torque angle ? causes a greater phase shift of back e. m. f. Eb w. r. t. supply voltage V. This increases the net voltage Er in the stator winding. Consequently, armature current Ia (= Er/Zs) increases to meet the load demand. iii) If the load on the motor decreases, the torque angle ? also decreases. This causes a smaller phase shift of Eb w. r. t. V. Consequently, the net voltage Er in the stator winding decreases and so does the armature current Ia (= Er/Zs). 11. 7 Pull-Out Torque There is a limit to the mechanical load that can be applied to a synchronous motor. As the load increases, the torque angle ? also increases so that a stage is reached when the rotor is pulled out of synchronism and the motor comes to a standstill. This load torque at which the motor pulls out of synchronism is called pull—out or breakdown torque.Its value varies from 1. 5 to 3. 5 times the full— load torque. When a synchronous motor pulls out of synchronism, there is a major disturbance on the line and the circuit breakers immediately trip. This protects the motor because both squirrel cage and stator winding heat up rapidly when the machine ceases to run at synchronous speed. 299 11. 8 Motor Phasor Diagram Consider an under-excited ^tar-connected synchronous motor (Eb < V) supplied with fixed excitation i. e. , back e. m. f. Eb is constantLet V = supply voltage/phase Eb = back e. m. f. /phase Zs = synchronous impedance/phase (i) Motor on no loadWhen the motor is on no load, the torque angle ? is small as shown in Fig. (11. 7 (i)). Consequently, back e. m. f. Eb lags behind the supply voltage V by a small angle ? as shown in the phasor diagram in Fig. (11. 7 (iii)). The net voltage/phase in the stator winding, is Er. Armature current/phase, Ia = Er/Zs The armature current Ia lags behind Er by ? = tan-1 Xs/Ra. Since Xs >> Ra, Ia lags Er by nearly 90Â °. The phase angle between V and Ia is ? so that motor power factor is cos ?. Input power/phase = V Ia cos ? Fig. (11. 7) Thus at no load, the motor takes a small power VIa cos ? phase from the supply to meet the no-load losses while it continues to run at synchronous speed. (ii) Motor on load When load is applied to the motor, the torque angle a increases as shown in Fig. (11. 8 (i)). This causes Eb (its magnitude is constant as excitation is fixed) to lag behind V by a greater angle as shown in the phasor diagram in Fig. (11. 8 (ii)). The net voltage/phase Er in the stator winding increases. Consequently, the motor draws more armature current Ia (=Er/Zs) to meet the applied load. Again Ia lags Er by about 90Â ° since Xs >> Ra. The power factor of the motor is cos ?. 300 Input power/phase, Pi = V Ia cos ?Mechanical power developed by motor/phase Pm = Eb ? Ia ? cosine of angle between Eb and Ia = Eb Ia cos(? ? ? ) Fig. (11. 8) 11. 9 Effect of Changing Field Excitation at Constant Load In a d. c. motor, the armature current Ia is determined by dividing the difference between V and Eb by the armature resistance Ra. Similarly, in a synchronous motor, the stator current (Ia) is determined by dividing voltage-phasor resultant (Er) between V and Eb by the synchronous impedance Zs. One of the most important features of a synchronous motor is that by changing the field excitation, it can be made to operate from lagging to eadin g power factor. Consider a synchronous motor having a fixed supply voltage and driving a constant mechanical load. Since the mechanical load as well as the speed is constant, the power input to the motor (=3 VIa cos ? ) is also constant. This means that the in-phase component Ia cos ? drawn from the supply will remain constant. If the field excitation is changed, back e. m. f Eb also changes. This results in the change of phase position of Ia w. r. t. V and hence the power factor cos ? of the motor changes. Fig. (11. 9) shows the phasor diagram of the synchronous motor for different values of field excitation.Note that extremities of current phasor Ia lie on the straight line AB. (i) Under excitation The motor is said to be under-excited if the field excitation is such that Eb < V. Under such conditions, the current Ia lags behind V so that motor power factor is lagging as shown in Fig. (11. 9 (i)). This can be easily explained. Since Eb < V, the net voltage Er is decreased and turn s clockwise. As angle ? (= 90Â °) between Er and Ia is constant, therefore, phasor Ia also turns clockwise i. e. , current Ia lags behind the supply voltage. Consequently, the motor has a lagging power factor. 301 ii) Normal excitation The motor is said to be normally excited if the field excitation is such that Eb = V. This is shown in Fig. (11. 9 (ii)). Note that the effect of increasing excitation (i. e. , increasing Eb) is to turn the phasor Er and hence Ia in the anti-clockwise direction i. e. , Ia phasor has come closer to phasor V. Therefore, p. f. increases though still lagging. Since input power (=3 V Ia cos ? ) is unchanged, the stator current Ia must decrease with increase in p. f. Fig. (11. 9) Suppose the field excitation is increased until the current Ia is in phase with the applied voltage V, making the p. . of the synchronous motor unity [See Fig. (11. 9 (iii))]. For a given load, at unity p. f. the resultant Er and, therefore, Ia are minimum. (iii) Over excitation T he motor is said to be overexcited if the field excitation is such that Eb > V. Under-such conditions, current Ia leads V and the motor power factor is leading as shown in Fig. (11. 9 (iv)). Note that Er and hence Ia further turn anti-clockwise from the normal excitation position. Consequently, Ia leads V. From the above discussion, it is concluded that if the synchronous motor is under-excited, it has a lagging power factor.As the excitation is increased, the power factor improves till it becomes unity at normal excitation. Under such conditions, the current drawn from the supply is minimum. If the excitation is further increased (i. e. , over excitation), the motor power factor becomes leading. Note. The armature current (Ia) is minimum at unity p. f and increases as the power factor becomes poor, either leading or lagging. 302 11. 10 Phasor Diagrams With Different Excitations Fig. (11. 10) shows the phasor diagrams for different field excitations at constant load. Fig. (11. 10 (i )) shows the phasor diagram for normal excitation (Eb = V), whereas Fig. 11. 10 (ii)) shows the phasor diagram for under-excitation. In both cases, the motor has lagging power factor. Fig. (11. 10 (iii)) shows the phasor diagram when field excitation is adjusted for unity p. f. operation. Under this condition, the resultant voltage Er and, therefore, the stator current Ia are minimum. When the motor is overexcited, it has leading power factor as shown in Fig. (11. 10 (iv)). The following points may be remembered: (i) For a given load, the power factor is governed by the field excitation; a weak field produces the lagging armature current and a strong field produces a leading armature current. ii) The armature current (Ia) is minimum at unity p. f and increases as the p. f. becomes less either leading or lagging. Fig. (11. 10) 11. 11 Power Relations Consider an under-excited star-connected synchronous motor driving a mechanical load. Fig. (11. 11 (i)) shows the equivalent circuit for one phase, while Fig. (11. 11 (ii)) shows the phasor diagram. Fig. (11. 11) 303 (i) (ii) Input power/phase, Pi = V Ia cos ? Mechanical power developed by the motor/phase, Pm = Eb ? Ia ? cosine of angle between Eb and Ia = Eb Ia cos(? ? ? ) Armature Cu loss/phase = I 2 R a = Pi ? Pm a Output power/phasor, Pout = Pm ?Iron, friction and excitation loss. (iii) (iv) Fig. (11. 12) shows the power flow diagram of the synchronous motor. Fig. (11. 12) 11. 12 Motor Torque Gross torque, Tg = 9. 55 where Pm N-m Ns Pm = Gross motor output in watts = Eb Ia cos(? ? ? ) Ns = Synchronous speed in r. p. m. Shaft torque, Tsh = 9. 55 Pout N-m Ns It may be seen that torque is directly proportional to the mechanical power because rotor speed (i. e. , Ns) is fixed. 11. 13 Mechanical Power Developed By Motor (Armature resistance neglected) Fig. (11. 13) shows the phasor diagram of an under-excited synchronous motor driving a mechanical load.Since armature resistance Ra is assumed zero. tan? = Xs/Ra = ? an d hence ? = 90Â °. Input power/phase = V Ia cos ? Fig. (11. 13) 304 Since Ra is assumed zero, stator Cu loss (I 2 R a ) will be zero. Hence input power a is equal to the mechanical power Pm developed by the motor. Mech. power developed/ phase, Pm = V Ia cos ? Referring to the phasor diagram in Fig. (11. 13), (i) AB = E r cos ? = I a X s cos ? Also AB = E b sin ? ? E b sin ? = I a X s cos ? or I a cos ? = E b sin ? Xs Substituting the value of Ia cos ? in exp. (i) above, Pm = = V Eb Xs VEb Xs per phase for 3-phaseIt is clear from the above relation that mechanical power increases with torque angle (in electrical degrees) and its maximum value is reached when ? = 90Â ° (electrical). Pmax = V Eb Xs per phase Under this condition, the poles of the rotor will be mid-way between N and S poles of the stator. 11. 14 Power Factor of Synchronous Motors In an induction motor, only one winding (i. e. , stator winding) produces the necessary flux in the machine. The stator winding must draw re active power from the supply to set up the flux. Consequently, induction motor must operate at lagging power factor.But in a synchronous motor, there are two possible sources of excitation; alternating current in the stator or direct current in the rotor. The required flux may be produced either by stator or rotor or both. (i) If the rotor exciting current is of such magnitude that it produces all the required flux, then no magnetizing current or reactive power is needed in the stator. As a result, the motor will operate at unity power factor. 305 (ii) If the rotor exciting current is less (i. e. , motor is under-excited), the deficit in flux is made up by the stator. Consequently, the motor draws reactive power to provide for the remaining flux.Hence motor will operate at a lagging power factor. (iii) If the rotor exciting current is greater (i. e. , motor is over-excited), the excess flux must be counterbalanced in the stator. Now the stator, instead of absorbing reactive power, a ctually delivers reactive power to the 3-phase line. The motor then behaves like a source of reactive power, as if it were a capacitor. In other words, the motor operates at a leading power factor. To sum up, a synchronous motor absorbs reactive power when it is underexcited and delivers reactive power to source when it is over-excited. 11. 15 Synchronous CondenserA synchronous motor takes a leading current when over-excited and, therefore, behaves as a capacitor. An over-excited synchronous motor running on no-load in known as synchronous condenser. When such a machine is connected in parallel with induction motors or other devices that operate at low lagging power factor, the leading kVAR supplied by the synchronous condenser partly neutralizes the lagging reactive kVAR of the loads. Consequently, the power factor of the system is improved. Fig. (11. 14) shows the power factor improvement by synchronous condenser method. The 3 ? ? load takes current IL at low lagging power factor cos ?L. The synchronous condenser takes a current Im which leads the voltage by an angle ? m. The resultant current I is the vector sum of Im and IL and lags behind the voltage by an angle ?. It is clear that ? is less than ? L so that cos ? is greater than cos ? L. Thus the power factor is increased from cos ? L to cos ?. Synchronous condensers are generally used at major bulk supply substations for power factor improvement. Advantages (i) By varying the field excitation, the magnitude of current drawn by the motor can be changed by any amount. This helps in achieving stepless control of power factor. ii) The motor windings have high thermal stability to short circuit currents. (iii) The faults can be removed easily. 306 Fig. (11. 14) Disadvantages (i) (ii) (iii) (iv) There are considerable losses in the motor. The maintenance cost is high. It produces noise. Except in sizes above 500 RVA, the cost is greater than that of static capacitors of the same rating. (v) As a synchronous m otor has no self-starting torque, then-fore, an auxiliary equipment has to be provided for this purpose. 11. 16 Applications of Synchronous Motors (i) Synchronous motors are particularly attractive for low speeds (< 300 r. . m. ) because the power factor can always be adjusted to unity and efficiency is high. (ii) Overexcited synchronous motors can be used to improve the power factor of a plant while carrying their rated loads. (iii) They are used to improve the voltage regulation of transmission lines. (iv) High-power electronic converters generating very low frequencies enable us to run synchronous motors at ultra-low speeds. Thus huge motors in the 10 MW range drive crushers, rotary kilns and variable-speed ball mills. 307 11. 17 Comparison of Synchronous and Induction Motors S. Particular No. 1.Speed 2. 3. 4. Power factor Excitation Economy 3-phase Induction Motor Remains constant (i. e. , Ns) from Decreases with load. no-load to full-load. Can be made to operate from Operates a t lagging lagging to leading power factor. power factor. Requires d. c. excitation at the No excitation for the rotor. rotor. Economical fcr speeds below Economical for 300 r. p. m. speeds above 600 r. p. m. Self-starting No self-starting torque. Auxiliary means have to be provided for starting. Complicated Simple More less Synchronous Motor 5. Self-starting 6. 7. Construction Starting torque 308

The Complete Writing Guide on a Public Relations Term Paper

The Complete Writing Guide on a Public Relations Term Paper Being a student means being challenged with ideas of where to start or how to finish any given assignment. Meanwhile, the teaching and studying processes always are aimed at revealing the already existing ideas and concepts, and at the same time encouraging students to develop their thoughts. Once you get the task to write a term paper, your professor probably waits for your paper as soon as possible. Know why? Not only because he/she wants to put a mark for your research and writing, but because your term paper is a source where everyone can familiarize with new explorations of the field. In your case, it is Public Relations. Nonetheless, most students fail to write their term papers. The common reason for such failures is a disregard of basic writing instructions or the lack of knowledge or skills about what writing a specific type of paper means. Let’s discover your particular assignment a public relations term paper in detail. Get Started to Write a Term Paper on Public Relations So the time has come for writing your first term paper. If your discipline is Public Relations, then writing a term paper sounds even more challenging just because of the variety of topics in public relations. Nonetheless, the first point which you have to familiarize with is what a term paper means and why it is so specific for you. As a type of research paper, a term paper is especially important because it accounts for the largest part of a grade. With that in mind, a term paper appears to be more valuable in comparison to essays or other research papers. However, it means that you shouldn’t pay much attention to essay and research paper writing on public relations. Term papers are writing assignments in which a student is supposed to argue a specific point. That is why, presenting an interesting, controversial topic is a basic step to start with. First of all, you should brainstorm the issues you can write about. In order to brainstorm effectively, take a paper and a pen. Write the main concept or a topic which came into your mind. You may even use colored pencils for categorizing your research elements. Choose the Most Interesting Topic in Public Relations for a Term Paper Further, think of the other concepts and problems the main topic associates with. When it comes to term paper writing, think of the material which you learn during the term: What assumptions appear interesting to you? What ideas do you agree/disagree with? What field of study would you like to investigate more? and so on. At the same time, think of the notions you strongly disagreed with. The more topics and controversial ideas you find, the more opportunities to choose a definite subject you have. Usually, a professor offers a list of topics for term papers. However, students are sometimes asked to find a topic by themselves. While searching for a topic, focus on the innovation which your term paper may present. For instance, the use of technologies in modern public relations. The title of your term paper may sound like â€Å"The Use of Digital Elements in Public Relations† or â€Å"The Importance of Technological Progress in Public Relations.† Here is a list of public relations term paper writing topics which you may find interesting for writing a term paper on public relations. Negative and Positive Influence of Social Media on Public Relations; Employee Generated Content and Public Relations; X Modern Changes in the Public Relations Agency Model; Public Relations Agency Model in the Future; How to Make the Crisis and Reputation Management Effective; The Relationship of Public Relations and Globalization. All topics are related to the importance of public relations in the communication with external organizations. Along with that, public relations term papers can communicate the social significance of a company as well as increase its credibility and reputation, yet the company’s status in the business world. Find the Best Sources of Information for Your Term Paper After you define the topic of your term paper, you may start your research. Make a list of the sites and databases which may contain the useful information. The most helpful databases are JSTOR, Google Scholar, ScienceDirect. Remember that you should use only credible sources. While performing in-depth research, try to make notes whether in schemes or just text passages. You may be surprised how such notes may be useful in case you have run out of ideas. Develop a Strong Thesis Statement for Your Public Relations Term Paper Further, you should create a thesis statement which is a â€Å"heart† of your term paper. Thesis statement implies a meaningful idea which you are going to offer to the audience or in other words, a simple notion to defend which meanwhile is an answer to the core question of your paper. For instance, if you have chosen a topic â€Å"The Use of Digital Elements in Public Relations,† then your primary question is â€Å"Why are digital elements important in Public Relations?† Later, your thesis statement, which is an answer to the question above, may sound as following: ‘The use of digital elements is extremely useful in the public relations as the former constitutes the entire system of messaging between the internal elements of the company and the external organizations.’ Remember that any statement needs significant reasoning. With that in mind, a statement like â€Å"Digital elements are important in public relations† is not enough to persuade your reader and prove the meaningfulness of your assumptions. Be creative but present only credible information. Prepare a Well-Organized Outline of Your Term Paper The last preparation step is an outline. Certainly, you may skip this step and start writing immediately. However, such an approach may complicate your process of writing as you may lose your track of thoughts, and your paper will look messy because of unexplored ideas, yet confuse the reader. Obviously, to make your essay perfect, you should write down an outline to set your ideas in order. Though the Internet may offer you some specific types of outlines, the most common type contains the following parts: Introduction with the thesis statement, Body parts, Conclusion and recommendations. Our Experts Give Advice on the Principal Amount of Work on a Public Relations Term Paper The first part of any academic paper is an introductory paragraph. The latter provides a basic knowledge of a subject which is going to be discussed. In academic papers, an introductory paragraph does not have to grab the reader’s attention as such type of a paper is not a magazine or newspaper article. Indeed, the first sentence should represent the overall facts about the topic. For instance, an introductory paragraph for a term paper which discusses the above-mentioned topic â€Å"The Use of Digital Elements in Public Relations† may start with the following sentence: ‘Technological progress has become an irreplaceable part in the modern world and has constantly been affecting the businesses.’ Do not start your introductory paragraph with your thesis statement! Further, you should add more information about the issue you are going to investigate and its importance. For instance, you may refer to the history of the digital elements in regards to public relations and find how digital discoveries passed into the system of public relations. The last sentence of your introductory paragraph should be the thesis statement. Congratulations! You have done everything to start persuading your readers by strong arguments which are going to constitute the main part of the paper its body. The body paragraphs should contain no less than four full lines. Additionally, keep in mind the need to use transitional words and phrases for the primary reason of connecting the sentences and creating a logical presentation of argumentations. At the same time, remember to use transitional words for comparison, clarification, contrast, conclusion, etc. Also, never start your sentences with conjunctions. To achieve a proper structure, divide draft variant of the paper into several sections which would contain the main concepts. In accordance to the topic â€Å"The Use of Digital Elements in Public Relations,† your sections may be as following: â€Å"The General Implementation of Digital Elements in Public Relations†, â€Å"Electronic Public Relations†, â€Å"The Suggestions for the Future Development of Digital Elements in Public Relations† As you see, all sections of your paper should discuss different subtopics which reveal the subject of your paper and serve as a definite proof for the thesis statement. At last, the paragraphs should contain references which are also additional credible evidence for your assumptions. The last part of your paper is conclusion which usually goes as a separate section. In the conclusion part, you should mention the results of your study or to be more precise, rephrase the thesis statement and then demonstrate the evidence which you have come to during your research process. Being a summary of the paper, the conclusion is the most well-developed part which presents the results in proper order. Remember the strict rule while writing your conclusion: do not include new information which has not been mentioned in the paper as this confuses the reader and makes your track of thought unclear. Create a list of sources you referred to. An appropriate system of referencing will help avoid plagiarism as academic integrity is the main condition which allows the professor to trust you and makes you a professional writer. Depending on the format which your paper requires, the name of the list which contains sources will be called References (for the APA format), Bibliography (for the Chicago style) or Work(s) Cited (for the MLA format). The Internet will offer you various citing programs. However, it is recommendable that you check your citations by the special guides. Such book as How to Write a Lot: A Practical Guide to Productive Academic Writing (LifeTools: Books for the General Public) by Paul J. Silvia will be of great help to you. Meanwhile, installing an anti-plagiarism software is another efficient step to avoid academic dishonesty, for instance, PlagTracker and PlagScan. The most popular plagiarism and grammar checker of modernity is Grammarly. It is easy for everyone to get access to Grammarly as the program is free. Though any plagiarism checker is considered an effective tool for the detection of academic dishonesty, the additional grammar checking is highly advisable. After checking the grammar by the software, read your paper one more time. Use the following questions to stay confident about the quality of your paper: Is the text properly divided into paragraphs? Are the words in the names of the sections and subsections capitalized? Is your paper well-structured? Does it contain the repeating thoughts which should be avoided? Is the additional information properly cited? Are the sources presented in alphabetical order in the List of References? While checking the paper, pay attention to the structure of the sentences and the language. Do not make the sentences cumbersome it is better to divide a complex sentence into some short sentences if the complex structure makes the sentence messy. Be specific in your evidence and be clear in your track of thoughts. At the same time, avoid using non-academic language, for instance, the elements of slang or colloquial words: use â€Å"allow† instead of â€Å"let,† â€Å"child† instead of â€Å"kid,† etc. Remember that language is your tool for writing the paper, yet you should present an excellent knowledge of an academic language that will help you write a high-quality paper. Now let’s sum up the tips of writing a term paper! The Ingredients of a Good Public Relations Term Paper Writing Process: Brainstorm and research the topic; Create a strong thesis statement; Write a detailed outline; Write the body paragraphs: the part where you will present your evidence for the argumentation; Conclude logically; Write a list of references; Check the style and format; Check the grammar. 3 Points to Avoid While Writing a Term Paper on Public Relations: Boring and meaningless topics. Pretend to be an innovator and find an issue which would be interesting for being explored. Think of innovation. Ask yourself: how can my idea be meaningful? Your professor will value your attempt to demonstrate the thinking-outside-the-box skills. Plagiarism. Academic dishonesty is the main enemy you have to fight with to deliver a high-quality paper. Certainly, your professor has already familiarized with the majority of the professional literature. Now your professor is interested in your ideas. Be free to surprise your instructor. Non-academic language. Your professor knows what the words â€Å"dude† or â€Å"guy† mean. However, it would not be a bright idea to put them in a term paper. Remember that formal language is the best option for an major textual assignment. 3 Points to Consider While Writing a Term Paper in Public Relations: This means that the more thoughts are yours, the higher are your chances to get an excellent grade. Nonetheless, this does not mean that you should not refer to the studies of other researchers. Indeed, you must refer to the credible sources and properly cite them to avoid academic dishonesty. Proper research. This means the use of credible sources and perfect knowledge of the investigated subject. That is why using credible databases and sites is highly advisable while searching for information. Such databases as JSTOR, Google Scholar, ScienceDirect, and Web of Science will appear to be helpful for your research. Writing style. As it has been mentioned, academic language is the core requirement in any academic paper. To refine your grammar, use the grammar-checking software along with the anti-plagiarism one. For this purpose, Grammarly is the best option as the program will allow you to simultaneously check the grammar and avoid plagiarism. In addition, the program is free which is a wonderful advantage if you are a student. Though perfectness is difficult to achieve, no one has forbidden you at least to try to reach it. Now, you’re ready to write a term paper on Public Relations as required by your instructor. We’re sure you’ll do it effectively for your academic performance and the field of study in particular. Just follow our public relations term paper guide step by step!

A Day in the Life of Alex Sander Essays

A Day in the Life of Alex Sander Essays A Day in the Life of Alex Sander Paper A Day in the Life of Alex Sander Paper Greiner and Collins article A Day in the Life of Alex Sander: Driving in the Fast Lane at Landon Care Products discusses the personality traits and behavior of Alex Sander and how it not only limits his career growth but also affects others within the organization.  Alex Sander, a MBA graduate of MIT, is a product manager in the Toiletries division at Landon Care Products, Inc. Alex is a highly talented individual, a fast learner, has entrepreneurial skills with extensive market and product knowledge, is self confident, and self driven. He successfully rebranded two skin care products in over a years time. However, Alex is emotionally immature and aloof from his colleagues at work. He has a commanding personality as he not only micromanages people but also derides them if he is not satisfied with their work output and this behavior alienates him from other people in the organization. Alex admits that he gets ticked off pretty easily, is very inflexible at work relationships, and expects everyone to put in extra hours even if they have prior commitments. He thinks that his temper is actually an effective management tool that makes people finish tasks on time but does not realize that he is losing credibility among his peers and subordinates. Despite his work effectiveness and efficiency, Alexs difficult behavior and disregard for co-workers feelings is limiting his desire to move further up in the organization. Based on the feedback from other people at his work place, Alex works tirelessly. However, the flip side is that Alex expects others to work the same way, and if they do not meet his expectations, then he feels that they lack commitment and dedication. Alex contributes to a negative work environment through humiliation and yelling causing nervous and frustrated co-workers. While Alexs subordinates and coworkers respect him, they dont see him as a leader due to his lack of ability to motivate people and get work done through other people. This was revealed during Alexs 360 review with his manager Sam Glass. Sam wants to keep Alex as he is a valuable asset to the company; however, Sam wants to find ways to help Alex take charge on changing his behavior.  In conclusion of the article, Alexs manager Sam discusses this issue with another colleague at his hierarchy level to identify the best possible option to rectify Alexs attitude and behavior. Comments and Recommendations Alex needs to show more concern to the feelings and insights of his peers, as well as take the 360 review more seriously as a tool to improve his weaknesses. Alex should take emotional intelligence (EI) training that can help him read emotional and social cues from others. He should also focus on developing his interpersonal skills and leadership qualities including leading through motivation and leading by example. Further, his manager, Sam should enforce Alex to implement a reward system to praise co-worker contribution.

Major Types Of Essays

Major Types Of Essays Learn the Most Widespread Types of Academic Essays In order to be successful in academic writing, you should be familiar with different types of essay. It is essential to understand what this particular kind of essay requires from you. There are a lot of top essay writing services which are always eager to help you perform your writing task no matter what type of essay it is. But don`t worry if you have never dealt with a descriptive or an argumentative essay. Almost all good writings begin with the terrible first efforts. You start from nothing and learn as you go. Here are the descriptions of the most popular types of essay. Describe Somebody or Something in Vivid Detail in Your Descriptive Essay â€Å"Describe a place you always wanted to visit†, â€Å"Describe a place where you feel safe and protected†, â€Å"Describe your best friend† – if you have received a similar writing prompt, it means that you are asked to write a descriptive essay. So, what is it actually? While writing this type of essay, you can take advantage of your artistic freedom and vivid imagination. Your main task is to create the unforgettable image by using imagery creatively. What is important to remember while writing a descriptive essay? Your title and introduction should be creative and appealing. Use quality, relevant and telling details. Don`t use repetitive ideas throughout. Let your audience feel, smell, picture and imagine things you are describing. Add your personality. Write from your knowledge or experience. h2Make a Claim and Prove Your Point in Your Argumentative Essay/h2 In the argumentative essay, you have to give your opinion on issues our society care most about. For example, you can be asked to answer such questions: - How should schools address bulling? - Does technology make us more alone? - Does reality TV promote dangerous stereotypes? Your primary aim is to change your reader`s attitude towards something by using proved facts, vivid illustrations and firm language. Of course, there can be a lot of people, who may have the opposite ideas. So, be always ready to fight against them. What is important to remember while writing an argumentative essay? Consider both sides of the argument before you choose your position. Show your ability to refute and anticipate any opposing arguments. Present the argument judiciously and fairly. Support your points with research and examples to strengthen your position. Don`t forget to explain to your audience why this particular issue is commonly debated. Explain a Topic or Inform Your Readers about Something in Your Expository Essay The purpose of a good expository essay is to explain, describe and inform. You are not allowed to write in the first person or reveal your personal feelings and emotions. Just use facts, statistics, and examples to define your topic. This type of essay requires a profound research to be carried out. The expository essay will help you practice your informative writing skills. There can be a variety of topics to choose from: Think about an occupation that is considered demanding or difficult. Describe true leadership. Describe the major stressors in teen`s lives. It is quite simple to write an expository essay if you bear such important things in mind: Organize your thoughts by using effective brainstorming techniques. Evaluate your sources for reputability and timeliness. Use attention getters such as questions, quotes or interesting facts. Explain in detail one of the main ideas in each body paragraph. Present information in logical and organized fashion. Reflect on the significance of the information you present. It is important to remember that expository essay encompasses many essay variations such as: HOW-TO ESSAY – explain how to do something paying close attention to details. CAUSE AND EFFECT ESSAY – explain the results or the reasons of the situation or effect. COMPARISON AND CONTRAST ESSAY – explain differences and similarities between two subjects. PROCESS ESSAY – explain to your audience how to perform a particular task. Create a Story in Your Narrative Essay Let your creativity flow here. Your task is to make up a good story that is worth of excitement. You do not have to forget about several important elements if you want to do it in a right way. These elements include theme, mood, setting, characters, and plot. You can pick the question that inspires you the most to tell an interesting story. For example: What challenges have you overcome? What are your fears and phobias? When have you failed? What is important to remember while writing a narrative essay? Introduce your characters and describe the setting in the introduction. The body of your essay should contain most of the plot. Finish describing the action in the conclusion. Deliver the moral of your story or make a revelation or a prediction in your final sentences.

Article Review Example | Topics and Well Written Essays - 750 words - 12

Review - Article Example The major functions generally involve searching of the relevant literature for establishing the contact with the discipline for writing the relevant literature. At the time of searching of the literature, practitioners are faced with various challenges. In this regard, the practitioners search for the journals which are not accessible for everyone. Some journals are only accessible for key users, which are recognized as one of the big issues for the practitioners. The second problem relates to the accessing of the journals during the research. There are few prominent solutions, to this issue, such as many sites are provided for accessing the articles without any subscription charges and the research scholars are suggested to figure out a list of the relevant journals for the research purpose (Carr &Briggs, n.d.). The study is based upon the indirect behavioral observation. Thus, the study is qualitative in nature. Correspondingly, the research design has been established. The study can be referred to base on indirect observation as it involves reviewing the articles of others. The research design will be rated three as per the SMRS application (The National Autism Center, 2009). The measurement of the dependent variable is related to the availability of the subject related literature articles. The practitioners are engaged in exploring articles of others. Hence, they are dependent upon the availability of such accessible articles. The indirect observation also explains that the problems related to the unavailability of the accurate articles are the dependent variable of the research. On the basis of the given information, the writer will rate four by using the SMRS (The National Autism Center, 2009). The independent variable of the study is the subject of the research paper. On the basis of the indirect observation, it can be determined that approximately 80% of the literature review to be