Racism in Roll of Thunder Essay Example for Free

Racism in Roll of Thunder Essay Mildred Taylors remarkable novel, Roll of Thunder, Hear My Cry, annotates, portrays, and demonstrates the vivid image of the ugly race prejudice, effectively, that the African Americans experienced in the 1930s, during the American Depression. In Taylors enthralling novel, racism comes across as a major and influential theme as the novel progresses and revolves around a young girl, Cassie Logan, who matures with racial conflict around her. Racism is apparent from the beginning of the novel. It is depicted from the beginning that African Americans are treated terribly, and they must work extremely hard, to earn the money they need to provide their family, with shelter, and food. Papa must work away from home to earn himself a good salary to keep the Logans own land, rather than working as sharecroppers on someone elses land. The second example of the callous segregation is evident, as it is seen that the elite white community have transport to school, while the harshly treated African Americans are deprived of this service, and are forced to walk to school. Also, the whites are inconsiderate, intentionally splashing mud on the blacks clothes. The Berrys burnings is a significant incident revealing the cruel manner the white community behave towards the African Americans, burning them taking a match to them, without any justifiable reason, portraying the discrimination between the people. At school, an important instance of racism takes place, when the students of the black school, The Great Faith Elementary School, received new books. These books were in the poorest condition, as they were the left-overs of the whites. The inside cover of the books were highly provocative, both insulting and offensive to the African Americans, using repulsive comments to describe their race such as nigra. The law also seems to be in favour of the white community, showing the extensive segregation between the whites and blacks. It is evident when Mr. Morrison explains why he lost his job Mr. Morrison was blamed in a fight with the whites, although it wasnt his fault. There are rarely any whites who are friendly with the whites, and those who are, are despised. This is the case with Jeremy, who walks to school everyday with the blacks. He is often bullied, mocked, and teased at school, and is beaten at home. The abhorrence of the underprivileged blacks by the whites is remarkably large, throughout the novel. As the novel progresses it is seen that Papa tries to explain to Stacey to hang out less with Jeremy, We Logans dont have much to do with the white folks. You know why? Papa says, believing that whites and blacks will never really be friends, Cause white folks mean trouble, with this it also demonstrates hatred between the two races. The intensity of racial discrimination is massive when TJ talks about the night men. The whites tarred and feathered him, making the African Americans feel inferior treating them of no value and worthless. Cassie, herself, is a victim of one of the racism incidents. On her visit to Strawberry, she is forced to apologize repeatedly to Lillian Jean, a white, humiliating herself greatly. Even her family, who are strong-willed, cannot prevent such things from happening trying to stay away from consequences. Cassie is mentally hurt after this situation. Racist comments are at is summit as the story progresses. Kaleb Wallace, to Mr. Morrison, sputtered, You big black nigger, I oughta cut your heart out for what you done! My brothers laid up like they is and you still runnin around free as a white man. Downright sinful, thats what it is! Why? I oughta gun you down right where you sit. This quote shows the filthy comments the whites use towards the blacks. As the story nears its conclusion, TJ gets influenced by the white community, and gets into stealing. TJ goes to a Barnetts store with his white friends, to get himself the pearl handed pistol. At the shop, the whites wearing a mask kill Mr. Barnett, a white man. TJ Avery is immediately entirely blamed for the sequence of events. This shows, again, the law in much favour of the whites as the police dont even look into the issue they dont care who is guilty, but immediately find a black man to blame. If the roles had been reversed, circumstances and the events that took place would have been completely different. The whites simply want to punish some blacks, and they can do so easily, as no one dares to stop them. Throughout the story, there are several racist remarks passed to the African Americans emphasizing the conditions they faced. Life for the African Americans in the 1930s was completely unjust. Judgment based solely on physical appearance exists, to date, and is still a controversial issue.

Tribological Audit Of Rolling Element Bearings

Tribological Audit Of Rolling Element Bearings 1. INTRODUCTION: In the current scenario, conservation of material and energy is very much important. As the principal cause of material wastage is wear, any reduction in wear leads to savings. Friction is the main cause of wear which leads to energy dissipation and damage to equipments. [1] Friction occurs when one surface drags upon another surface. The magnitude of frictional force depends upon the interaction of mating surfaces. All surfaces consist of minute asperities and depressions even though the surface has high degree of finish. From close observation it is clear that frictional force is produced due to the distortion of the micro asperities when one surface slides over the other. As most of the surfaces are elastic up to a limit, the original shape is regained afterwards. In extreme cases the asperities get removed due to plastic flow of materials. [4] This process of removal of material from one or both of two surfaces in contact is known as wear. [6] Lubrication is the most effective me thod to lower the friction and to control wear and tear. Lubrication is the process of interposing a solid liquid or gaseous lubricant in between two surfaces in relative motion in order to decrease wear and tear. [6] Tribology is the science of interacting surfaces in relative motion and of related subjects and practices. [5] Tribology is derived from the Greek word Tribos which means rubbing. It deals with relative motion of the bodies, friction, wear and lubrication. The motion of the bodies includes sliding, rolling, spinning, bouncing or combination of these. [5] The written history of tribology is as old as about five thousand years. In olden days itself people were concerned about friction and the ways to reduce it. Assyrians used rollers made of wood to move massive stones. [2] Later carts are developed as rolling friction is less than sliding friction. Although the ways to reduce friction was highly concerned from the olden days itself, the word tribology was introduced in 1966. [5] The minimum film thickness in tribological machine elements was in the order of 10 µm to 100 µm at the start of the century. Later advance in the tribology led to the development of components with film thickness up to 1 µm. The thickness is further reduced to 0.1 µm by the end of the century. In short, tribolo gy in the important factor in design of machine elements and selection of lubricants. [5] 2. ROLLING BEARINGS: Invention of wheel led to minimise the effort of moving an object as rolling friction is less than that of sliding friction. Even though rolling motion produces less friction, man was seeking different ways to decrease the rolling friction. This led to the discovery that bearing based rolling motion consumes less power. Hence it was implemented in all rolling systems including complex machine mechanisms. In earlier periods the roller bearings was not able to compete with the hydrodynamic sliding bearings as it cannot meet with the endurance characteristics of the other. The roller bearing was universally accepted in the 20th century by the development of superior bearing materials and advanced techniques. This helped to manufacture roller bearing assemblies with extreme accuracy and long life. The competition among the manufacturers increased in early 1970s which led to a sudden increase in the production of high quality products at relatively low costs. [2] Rolling bearing includes all types of bearings to permit minimum friction between two moving surfaces relative to one another. The main application of roller bearing is to rotate a shaft relative to some fixed or oppositely rotating structure. It also allows relative linear motion of a fixture in a fixed direction provided by a stationary shaft. [3] Usually a bearing consists of two steel rings each of which consists of a hardened raceway. The hardened steel balls or rollers roll in these raceways. These rolling elements are usually held in an angular spaced structure which is called separator or retainer. [2] ball.gif Figure 1- Ball Bearings [7] There are different types of roller bearings based on their analysis of operation. A brief description on various types of bearings is explained below. 2.1 BALL BEARINGS: 2.1.1 Radial Ball Bearings: Radial ball bearings are the most popular rolling bearings. This type of ball bearings has an inner and outer raceway grooves in between the balls are inserted. The grooves have curvature radii of about 53% of the size of the ball diameter. The inner groove is concentrically fixed inside the outer groove and the ball bearings are present in between the grooves. The bearings are separated uniformly. A cage is used to maintain the separation. Deep groove ball bearings have the capacity to carry more loads as it is having large ball diameter. It can carry radial as well as thrust loads. Seals are present to keep the lubricant in and protect from external dirt. [2] Figure 2- Radial Ball Bearings [8]radial-bearings.jpg 2.1.2 Angular Contact Ball Bearings:406px-Angular-contact-ball-bearing_single-row_din628_type-b_120.png Angular contact bearings are designed to withstand heavy thrust loads or a combination of both thrust and radial loads. The ball bearings have a contact angle which does not exceed 40 degrees. Single and double row ball bearings are usually used depending upon the nature and magnitude of force to withstand. In this type of ball bearings, the outer raceway is the part of a sphere. The load applied on the outer raceway is minimised as the balls do not conform well into it. By using large balls the load on each ball can be minimised. This type of bearings can be used in applications where the parallelism of shaft and the housing are not exact to each other. [2] Figure 3- Angular Contact Ball Bearings [9] 2.1.3Thrust Ball Bearings: thrust-ball-bearing_din711_ex.png Thrust bearings are those bearings having a contact angle of 900 which can withstand thrust loads. These types of bearings are meant for high speed applications. The thrust bearings are mounted on spherical seats to obtain high degree of alignment ability. These bearings cannot be used to hold any radial loads. [2] They are mainly used in automotive, marine and aerospace applications. These increase smoothness and help in noise reduction thereby reducing friction in the attached part. Small size, reduced friction and long life are the main advantages of thrust bearings. [10] Figure 4- Thrust Ball Bearings [11] 2.2 ROLLER BEARINGS: Roller bearings are used in applications where the bearings have to support very high loads. Rollers are used in these bearings instead of balls. In these roller is cylindrical in shape and so line contact is formed between rollers and raceways. This spreads the load out a large area. Hence they have more load supporting capability. [12] They supply more fatigue endurance than ball bearings. Also the cost of manufacturing is high. These bearings consist of two concentric raceways which consist of rollers in between the two. To increase the load carrying capacity, cylindrical bearings with two or more rows of rollers are constructed. Different types of roller bearings include needle roller bearings, tapered roller bearings, thrust roller bearings and spherical roller bearings. [2] Roller-Bearing.jpgLB_OP_Linear_Motion_Bearing_250x250.jpg Figure 5- Roller Bearings [13] Figure 6- Linear Motion Bearing [14] 2.3 LINEAR MOTION BEARINGS: Linear motion bearings are the recent products developed in order to provide free motion in one dimension. In machine tool slide ways, very high friction is developed. Linear motion bearing consists of balls which carry the loads laterally in a particular direction and hence wear and tear can be minimised. They provide smooth, precision, guiding surface. The rolling element of a linear bearing rides over it thereby reducing friction. [15] 3. TRIBOLOGICAL FACTORS: Tribology deals with friction, wear and lubrication. The two key factors related to tribology are interacting surfaces and relative motion. It is clear that tribology is concerned with two surfaces in relative motion which are adequately close to one another. Usually a poor tribological interface is designed and then various lubricants are used to lower the friction between the surfaces. The most acceptable way is to design a better interface which includes the selection of a good lubricant also to minimise the friction and wear to the lowest. [5] Various tribological factors are to be taken into consideration while taking a situation. The important tribological factors include: Material Surfaces Lubricants Operating Conditions [5] 3.1 MATERIAL: The initial step to be taken while designing a product is the material selection. There are various factors which are taken into consideration while selecting the material. For tribological point of view the following factors are to be given importance before material selection. Basic Mechanical Properties Friction Wear Resistance Compatibility [5] 3.1.1 Basic Mechanical Properties: The basic mechanical properties of the material such as elastic modulus, Poissons ratio, yield stress, hardness, fatigue resistance, ultimate tensile strength and thermal conductivity are to be analysed. [5] Also the availability and cost of the material are also taken into account. Based on these observations the best material suitable for the manufacturing of bearings is selected. The selection of material used for bearings is to be done carefully based on standard specifications. The material plays an important role in the performance of the bearings. This affects the overall performance of the machinery also. The selected material is used to manufacture the load bearing parts of the bearings like raceway grooves and balls or rollers only. Retainers and cages are made from some other soft materials with desired qualities. [17] 3.1.2 Friction: Friction is the resistance offered by two interacting surfaces in relative motion. The degree of friction is denoted by coefficient of friction  µ. [6] Friction occurred during sliding is known as sliding friction and which occurred during rolling is known as rolling friction. The main factors which cause friction are adhesion between surfaces, surface hardness, asperities etc. [6] 3.1.2.2 Laws of Friction: There are different laws of friction which are applicable to dry friction between interacting surfaces. The first and second laws were put forward by Leonardo da Vinci and third law was introduced by Coulomb. [6] The first law of friction states that force required to initiate or sustain sliding FT is proportional to FN, the normal force. [6] Thus FT ÃŽ ± FN or FT =  µ.FN [6] Where  µ = Coefficient of friction The second law of friction states that the friction force FT is independent of the apparent area of contact Aa [6] The third law of friction states that friction is independent of sliding speed. [6] It was found that the first two laws of friction are obeyed in almost all experimental conditions. Lubrication systems can be used to lower the friction developed within the bearings. Friction in bearings depends upon the viscosity of lubricant and shear rate. Self lubricated bearings are widely used as it offers only very low friction. [20] 3.1.3 Wear: Wear can be termed as the material loss or volume loss from the surface of the materials in contact. [21] The main types of wear occurring on material surfaces are adhesive wear, abrasive wear, fatigue wear, corrosive wear. The local pressure at the asperities becomes extremely high when the normal pressure is acted upon the mating surfaces. When the pressure exceeds a certain limit, the asperities deform plastically until the area of contact increased sufficiently to withstand the load. The wear produced due to adhesion process has been explained by Archard equation. Wad = K [22] Where Wad = wear rate K = wear coefficient F = normal load H = hardness of softer material When two dissimilar materials slide over one another, the softer material gets scratched away. Thias type of wear is called as abrasive wear. Fatigue wear occurs when a rotating shaft is subjected to reversal of bending stresses. Corrosive wear is due to the reaction of the material surface with the environment or an external agent. [6] Wear occurs in ball and roller bearings due to corrosion, shock loading of fatigue. Atmospheric agents like dirt and girt are the other external factors which are responsible for wear. [4] 3.1.4 Compatibility: Alloys are usually selected as bearing materials. Alloy is a solid composition consisting of two or more metals and elements in fixed proportions. The two alloys which are used to manufacture the bearings are Chrome Steel and Stainless Steel. Steel is an alloy of iron and carbon. [17] Various other elements like silicon, manganese, phosphorous, sulphur, chromium and molybdenum are added in chrome and stainless steels in order to increase the strength, hardness and corrosion resistance of the alloys. [18] Carbon is used in the alloy to form cementite structure and to formation of pearlite, spheroidite, bainite, and iron-carbon martensite. This improves hardenability of the alloys up to 0.65%. Wear resistance is increased up to 1.5%. Toughness of the alloy reduces and the brittleness increases when carbon is added. Manganese increases the hardness penetration of steel. Chromium is added to increase hardness, toughness and wear resistance to steel. Silicon acts as the deoxidiser during the manufacturing process. [19] 3.1.4.1 Chrome Steel Chrome steel is one of the widely used alloys to manufacture bearings. It is used mainly in high load bearing applications as this material is capable of withstanding very high loads. The machinability of the material is as high as highly finished, less noisy bearings are obtained. Also the life of the bearings is also very high. Under test conditions, the Rockwell hardness of the material is observed as 60 64 C. This material is used in applications where corrosion is not considered. [16] The constituent elements in the chrome steel are given in the table 1. 3.1.4.2 Stainless Steel The standard material used for the bearings is 400 series Martensitic Stainless Steel. This type of steel is highly resistant to corrosion and hence stainless steel bearings are used in applications where corrosion is to be taken into account. It is having less load withstanding capacity when compared to chrome steel. There are three types of 400 series Stainless Steel suitable for making bearings. These materials are developed by manufacturers to be used for certain specific applications. [16] 3.1.4.2.1 DR Stainless steel This material is highly resistant to corrosion and is used in applications which deal with highly corrosive medium. The material can be precisely machined so as to obtain high degree of finish to the surface of bearing. This helps in smooth, low noise operation of the bearings. The Rockwell hardness of the material is observed as 58 60 C. [16] The chemical composition of the material is given in table 2. 3.1.4.2.2 AISI 440C Stainless Steel AISI 440C Stainless Steel is highly resistant to corrosion and is easily available. But it is not widely used now a day when more modern materials are developed. The Rockwell hardness of the material is 58-60 C. [16] The chemical composition is given in table 3. 3.1.4.2.3 ES1 Stainless Steel: This material is highly resistant to corrosion and has high machinability. Thus highly finished surfaces can be produced. The material is having a Rockwell hardness number of 58 60 C. [16] The composition of the material is given in table 4. 3.2 SURFACE: Surface quality of the materials is one of the major tribological factors which determine the efficiency of the product. [4] Surface finish decides the amount of friction and wear of the material. Surface texture and conformity are the terms which are to be given importance. 3.2.1 Surface texture: The surface of the material is the part which interacts with the environment. The surface may not be highly finished due to several reasons. It may be due to the imperfections caused during manufacturing, due to external agents or due to loads acting on the surface. The deviations observed on the surface can be mainly classified into three which includes roughness, waviness and error of form. [23] Roughness is the surface irregularities which consist of rises and valleys. This creates an uneven surface pattern. Waviness is the small ups and downs on the surface which is having less amplitude that of roughness. These may be caused due to work piece deflections, vibration or heat treatment. Error of form is the slight deviations from the nominal shape. [6] The surface profiles can be traced by using different apparatus like Abbott profilometer, Tomilson surface finish recorder and Talysurf surface finish recorder. [4] 3.2.2 Conformity: Conformity is the degree of agreement between the surfaces. [5] An interface consisting of two plates is said to have high conformity. Journal bearing is an example for high conformity material. An interface consisting of a plate and a ball is said to be having low conformity. Ball bearing is an example for low conformity material. Conformity is an important factor which is to be considered as it has an important role in determining the pressure, shear stress and temperature in the interface. [5] Figure 7- Surface Texture [23] 3.3 LUBRICANTS: Lubrication is the technique employed to reduce wear by the interposition of a solid, liquid or gas between the two surfaces which come into contact with one another. It was a persistent problem for man for centuries from the day he used to move materials. Friction consumes and wastes energy whereas wear leads to the damage of the equipment which are undesirable and it has to be avoided at any cost. Every moving part of machinery is subjected to friction leading to wear and tear which has to be avoided. Lubrication plays a vital role in avoiding the friction between mating surfaces. The history of lubricant begins thousands of years before. It was found that the ancient Egyptians used lubricants to avoid friction in the wheels of chariots. [24] In ancient times lubricants were of animal, plant and marine origin. Later mineral oils were started to use as lubricant. The new science of lubrication based on hydrodynamics came in 1880s. [24] Lubricants are of solids, liquids and gases but liquid lubricants are widely used. These include mineral oil, synthetic oil, grease, vegetable oil and water. Lubrication is done by applying a thin film of lubricant between the surfaces in contact. [6] Thus undesirable problems like friction, wear, noise and vibrations can be reduced to a very high extent. 3.3.1 Viscosity: Viscosity of a lubricant is the main characteristic which is taken into account before selecting it for a specific application. Friction, heat generation, film thickness and load carrying capacity depend upon the viscosity of lubricant used. Generally viscosity can be stated as the hindrance of the fluid to flow. But based on lubrication, viscosity is the measure of ability of fluid to maintain lubrication at specific operating conditions. [24] 3.3.2 Lubrication Regimes: Lubrication can generally be classified into four different regimes based on the thickness of the fluid film in between the surfaces in contact. They include: Hydrodynamic Lubrication Boundary Lubrication Mixed Lubrication Elastohydrodynamic Lubrication 3.3.2.1 Hydrodynamic Lubrication: image8.jpg Figure 7- Hydrodynamic Lubrication [25] In hydrodynamic lubrication, a fluid film is formed in between the two surfaces in contact. Thus one surface floats on the other and there occurs no direct contact between the surfaces. In microscopic level the surfaces of the materials consist of asperities. In normal condition without lubrication, the asperities are in direct contact with each other. When one surface slides over the other, the asperities get deformed producing friction and hence wear. Hydrodynamic lubrication helps avoid the friction as there is no direct contact between the surfaces. The viscosity of the lubricant helps to increase the fluid pressure in between the surfaces. Thus the lubricant layer holds the surfaces apart. As the lubricant layer formed is thicker than the surface roughness of the material, one material slides over the other without damaging the surface. It is observed that the thickness of the film is more than 1 µm. [24, 25] The surface is separated apart by hydrostatic lift. A fluid flowing over a surface immediately takes the speed of the surface. Similarly when the fluid moves in a converging gap, the pressure increases and the surface is lifted. [25] 3.3.2.2 Boundary Lubrication: Boundary lubrication is a type of lubrication in which the surface roughness of the material is same as that of the fluid layer thickness. Thus when one surface moves upon the other, the asperities comes into contact. When load is applied the asperities gets plastically deformed which leads to friction and wear. As friction is not desirable different methods are also adopted to reduce friction in this type of lubrication. This includes the use of various additives to the lubricants. The additives are classified according to the surface action exhibited on the material surface. They are mainly of three types. Physically absorbed layers Chemically absorbed layers Chemical reaction layers 3.3.2.2.1 Physically adsorbed layers: When the lubricant is applied, it forms a layer on the material surface. The weak intermolecular force called van der Walls force exerted by the layer of the lubricant helps to attach to the surface. This layer lubricates and allows the other surface to slide over the other without causing friction. As the lubricant is not undergoing any chemical reaction, the process is reversible. The bonds formed by van der Walls force are weak and it can be removed. The main disadvantage of the physically adsorbed lubricants is that they have a temperature limit above which the lubricant melts. 3.3.2.2.2 Chemically adsorbed layers: Chemically adsorbed layers are those formed due to the chemical reaction with the surface material. Chemisorption is a type of adsorption in which the molecules are hold tight by the valence force of the molecules of the lubricant. The bonds created are stronger than the physically adsorbed layers. Usually chemically adsorbed lubricants form long chain fatty acid molecules, which has high affinity to metal surfaces. Fatty acid additives like stearic and oleic acid forms chemically adsorbed layers. The typical thickness of the boundary film is about 3 µm. As chemical reaction takes place in the interface, the adsorbed layer can be removed only under extreme conditions like high temperature, vacuum or by using some chemical treatments. [26] 3.3.2.2.3 Chemical reaction layers: Chemical reaction layers are formed by the reaction of additives in the lubricant with the surface of the material on which it is applied. In this adsorption is not taking place, instead a chemical reaction that bonds the lubricant and the material occurs. Thus the layers formed are permanent. The main disadvantage of physisorption and chemisorptions is the temperature limit above which the lubricant gets ineffective. In this type of reaction the working temperature is not a factor. Hence this type of lubrication is used in high speed and high load operating systems as high temperature is developed in these cases. Zinc dialkyl dithiophosphate (ZDDP) is widely used as an additive to produce effective chemical reaction films. [24] 3.3.2.2 Mixed Lubrication: Mixed lubrication has the features of both hydrodynamic lubrication and boundary lubrication. In hydrodynamic lubrication the contact surfaces are separated apart by the pressure of the lubricant interposed between the surfaces. Hence there will not be any contact between the two surfaces in motion. But in boundary lubrication, one surface rests on the other. When the surface moves the asperities gets plastically deformed which causes friction and wear. Mixed lubrication acts between the two extremes of hydrodynamic and boundary lubrication. In mixed lubrication regimes a fluid film layer is developed where contact takes place between the asperities of the surfaces. Thus a slight deformation is formed while sliding occurs which is highly desirable. The film thickness ranges from 0.05 µm to 0.1 µm. [25] 3.3.2.3 Elastohydrodynamic Lubrication: Elastohydrodynamic lubrication is a type of lubrication which brings together hydrodynamic lubrication, hertzian contact and change in viscosity with pressure. In this method of lubrication, the surface is modified to minimise friction. Elastohydrodynamic lubrication is used in applications where low conformity and highly loaded tribological interfaces are present. Roughness of the wearing surface is taken into consideration in this lubrication. Roughness is taken as the average of high and low points of the surface which is called as the centreline average. [27] A non conformal contact can produce pressure to a very high level. When the pressure increases it directly affects the viscosity of the lubricant. In normal conditions the viscosity of the lubricant is less noticeable but during elastohydrodynamic lubrication the viscosity increases which makes the lubricant act as a semi solid. This creates a thin film of oil in between the mating surfaces. [25] 3.4 OPERATING CONDITIONS: Operating conditions are the main aspect to be taken into account while designing a mechanical component including bearings. There are different factors which comprises the operating conditions. Load Relative Motion Temperature Environment 3.4.1 Load: The load applied on each ball and roller is to be determined to manufacture the bearings which can operate at the desired applications without failure. In order to calculate the load deflection relationship is to be developed for roller element contacting raceways. In almost all the applications the outer or inner raceways is in steady state rotation. The speed of the rotation may not be large enough to affect significantly the distribution of the load equally on each roller or ball elements. The rigidly supported bearing is subjected to radial load which may lead to deflection. The radial deflection at any rolling element is given by ÃŽ ´ÃË† = ÃŽ ´r cos ψ  ½ Pd [2] Where ÃŽ ´ÃË† = radial deflection r = ring radial shift ÃŽ ¨ = angular location Pd = diametral clearance Thrust load and roller bearings are also subjected to thrust loads which are distributed equally among the rolling elements. The thrust load can be calculated using Q = Fa / Z Sin ÃŽ ± [2] Where Q = thrust load Fa = applied load Z = number of rollers per row ÃŽ ± = contact angle 3.4.2 Relative Motion: Relative motion is the motion of either one or both surfaces with respect to each other. There are different forms of relative motion depending upon the style of motion. They include sliding, rolling, spinning and bouncing. Sliding refers to the smooth movement over a surface maintaining the contact between each other. Rolling is the movement by revolving within the axis. Spinning is the rotation of a material within its axis. Bouncing is the rebounding due to an impact. Chance for sliding occurs in the rolling bearings due to thrust loads. Bouncing may occur due to sudden fluctuation in loads which may lead to destruction of bearing material. 3.4.3 Temperature: Operating temperature is a factor which is to be taken into consideration for the smooth functioning of the bearings at load conditions. Temperature rise may occur in the bearings during operation which may be due to different reasons. One factor which causes the rise in temperature is the application of excess load. If excess load is applied, the material may not be designed to withstand that much high load. So it may lead to failure. Another reason for the temperature rise is the absence of lubricant. The lubricant should be interposed to the surfaces in contact. If it fails to continuously supply the lubricant to the surface, friction is produced which results in gradual rise in temperature. Various coatings are also used to overcome temperature extremes. 3.4.4 Environment: Nature of environment is the feature which can influence the efficiency and life of the bearings. There are different agents which affect the operating conditions of the bearings which may be harmful. These include contaminations like dust, wear particles, air, water, process fluid etc. Insulations are to be provided to avoid exposure to these external agents. This can be done by using seals or coatings. 4. CONCLUSION: The various tribological factors are to be considered while designing rolling bearings. This tribological audit looks for the different factors which affect the performance and life of the bearings. The major tribological factors found include material, surface, lubrication and operating conditions. Different solutions are available which can be applied to each factor to lower the friction. Material should be wisely selected which can be easily machined to obtain highly finished surfaces and should possess the strength to withstand the loads applying on it. The material should be selected according to the application. Surface texture and conformity of the material is to be carefully observed as the surface finish is one of the major factors which cause friction. Lubrication plays a major role in the performance of the equipment. Right method of lubrication is selected. Elastohydrodynamic lubrication forms the film with minimum thickness which is the most desirable in bearings. Operat ing conditions affects the performance and life of the bearings which includes contaminations like dirt, wear particles, water, corrosive process fluid etc. Proper measures are to be taken to avoid exposure to these agents. From this audit it is clear that we have to take care of the tribological factors and select the most suitable ones to obtain maximum performance and life to the rolling bearings.

The Role Of Religion In International Relations

The Role Of Religion In International Relations In this book, it is informed that how vital is religion in international relations. The resurgence of religion seen as the driving force behind the clash of civilizations. According to Pavlos Hatzopoulos and Fabio Petito, religion remains as a threat to international relations own existence. In other words, politics with reference of religion became a threat to security, order and civility. PART I INTERNATIONAL RELATIONS THEORY AND RELIGION Resurgence of religion and cultural pluralism in international relations challenged the Western culture of modernity and the institutions of international society. This resurgence is part of the larger crisis of modernity. It reflects a deeper and more widespread disillusionment with a modernity that reduces the world to what can be perceived and controlledthrough reason, science, technology and bureaucratic rationality , and leaves out considerations of the religious, the spiritual, or the sacred. And also, the global resurgence of religion is the failure of the modernizing, secular state to produce both democracy and development in the Third World. Moreover, the global resurgence of religion can be seen as a revolt against the West in developing countries.  [1]   People always want to belong to different faith communities or to none. Now, there is a growing evidence in international relations to what different kind of religious perspectives may have offer to the world. The rejection of the study of religion is more stronger in international relations than in most other social sciences. The common ethical principles among the main world religions on war, peace, the just war, pacifism, human rights and peace building are identified by the scholars in international relations, Christian Ethics, and Religious Studies. These social ethics are also examined by various nongovernmental organizations such as the World Conference on Religion and Peace (Amman, Jordon, 1999) and the Parliament of the Worlds Religions.  [2]   Deep pluralism focuses the approach called virtue-ethics. It focuses on virtues, practisesand community rather than the individual or or a cosmopolitan community of humankind as a whole. The necessary dinstinction between theology(faith) and reason and leaded this question, which is superior faith or reason? A virtue-ethics approach shows how humanitarian practises can help to build up communuties in their faith as well as empower them as part of development. It maybe the case that two should go together if there is to be lasting political stability, democracy and development.  [3]   Theological and religious thinking causes debates about the role of the culture on the international politics. The presumed unity of ethics and politics mostly disappered along with it . The concequences of extinction , and the changes in theoretical perspective entailed other political models or view points . A community is not merely an artificial set of arrangemets between people. An it certainly cannot be a moral community. Humans create the state out of their own self interest means that the state can exist only so long as it appeals to peoples sinful needs rather than to any capacity for virtue tahat e denies most possess in any case. And also people obey law because it is in their self interest to do so, not because they believe it is the morally correct thing to do so. For him does not consider political activity to be natural to people nor does he believe that people engage in politics for y reason except promoting their own self interest. The article analyzes several specif ic theological views on multiculturalism in world politics, including religious pluralism, apologetics and syncretism.  [4]  Each of these perspectives challenge the exclusivist views of religion. Theological pluralism has many similarities with liberalism, yet analyses more deeply and ultimately challenge liberalisms Enlightenment presuppositions. On the other hand, apologetics is a dialogical processes which are designed to overcome the problems associated with alterity apologetics is a dialogical processes which are designed to overcome the problems associated with alterity. Syncretist religious ethics points to the contingency and multiplicity of identity. Taking these approaches seriously may well resonate with the aspects of the English School.  [5]   It shouldnt be ignored that traditional preoccupation with the problem of power in assessing the value of theological ethics. Stressing power similarities and differences, and differences including whether religious practices reinforce or challenge dominant economic and political structures of power is a contribution to the study of religion. PART II WAR, SECURITY, AND RELIGION Often the political resurgence of religious communities is accompanied by violent clashes in and between nations among others. We can give as examples; the bloody conflicts in Algeria, Bosnia, East Timor, Kashmir, Nigeria, Palestine and Sri Lanka. Primordialists argue that differences in religious traditions should be viewed the most important variable to explain violent interactions in and between nations. The resurgence of religion represents a big challenge to the existing status quo. Primordialists argue that differences in religious traditions should be viewed the most important variable to explain violent interactions in and between nations.  [6]  Instrumentalists think that conflicts may be aggravated by divergent religious creeds but they insist that the yare rarely if ever caused by them. According to them, the correlation between violent clashes and resurgence of religion is not surprising but it is necessary.  [7]  By contrast, moderate constructivists argue that a cts of violence requiers legitimization and religion and religious leaders provide such legitimization.  [8]   There is three theorethical perspectives on the impact of faith on political conflict: primordialism, instrumentalism, and moderate constructivism. In this view, cultural similarities and dissimilarities produce converging and diverging state interests. Most religious conflicts in international politics are asymmetric. States which have similar religious traditions and cosmologies will want to form alliances against whom they share little cultural and religious ideas. Violence will be largely confines to interactions that take place between civilizations. Under the conditions of scarcity and value pluralism, conflicts among groups are a universal feature of social life. They can not be avoidedbut must be taken as a result of human nature.  [9]  The sources of conflicts are usually very complex. Religious factors sometimes play a subordinate role as a source of conflicts. There is four determinants of elites strategic choices. The first one is; the degree of mobilization depends on the nature of conflict. The second one is; the degree of mobilization depends on the self-sacrificing attitudes of the groups members. The more commited the more to invest time and resources, the more practicable will be. The other determinant is; the degree of mobilization depends on the relationship between the conflict parties. And lastly, the degree of societal support depends on the public justification for the use of violence. Also there is two conditions for a successful implementation of the dialogue strategy. First, there is a dilemma between the different religious communuties. Before they resist against the violence, they have to be sure about the other communuties do the same. If this does not happen,peace would become the stupid according to conservative scholars. Secondly, all great religious communuties are more or less entangled in violent political clashes. The sources of conflicts are usually very complex. Religious factors sometimes play a subordinate role as a source of conflicts. Since the end of the Cold War, conflicts and wars are less because of political or ideological systems. And also they are not much caused by economic motives or territorial and because of gaining power. The motivations of conflicts are increasingly related to culture and identity. Or in other words, conflicts cause by ethnic or clash of civilizations. The resurgence of religion represents a big challenge to the existing status quo. And also they are not much caused by economic motives or territorial and because of gaining power. Most religious conflicts in international politics are asymmetric. Often secular states are attacked by religious groups. A threat from a religious group known for using terrorist methods. And this situation generally seen as a direct threat to sovereignty of the state. A religious attack on a secular state can be seen as one of the three main ways in which religion can be addressed within the realm of security politics  [10]  : A religious group is considered to be a threat to the survival of the state. Faith is seen as threatened by whoever or whatever nonreligious actor or process (the state, technology, industrialism, modernism, etc.). Faith is seen as threatened by another religious discourse or actor. Especially securitization on behalf of secularization against fundamentalism justifies many violations of democracy and civil liberties around the world. From a secular platform, religion as such can be depicted as a threat to political culture. On this issue international relations theory is not neutral observer as it pretends to be. It is implicated by its own secularist self perception.  [11]   PART III POLITICIZING RELIGION: TOWARD A NEW GLOBAL ETHOS? Inclusivism strives for a religious identitiy that exceed the locus of the sovereign state and the time frame of the present; it alternatively rests on a future fulfillment. Inclusivist religion can help to diminish the obstacles to a needed and desirable reconciliation of science, reason and sprituality.  [12]  Religion can bring clarity and charity to debates about a range of grievances regarding past abuses. Humane global govarnance can only ocur as the outcome of human struggle and to past efforts to overcome colonialism, slavery. The cultural division between East and West was historically neat and rigid. Between Christian and Islamic spirituality we can see familiar themes, but also a kind of sea change. In the Islamic context, intellectual spirituality is not a compact movement and it subscribe to a unified doctrine. Desecularization becomes a very important dimension of the intellectual and historical context. In this context, religion becomes an increasingly important factor in transnational and international relations. Because of the significance of religion in political arena, the Islamic resurgence in twentieth century viewed as the rise of political Islam. As a consequence, while the resurgence involves many dimensions, its political impacts received more attention. Political Islam have many types of movements. There have been movements advocating internal legal reform, the transformation of social institutions through legislation as well as social persuasion, revolutionary change of the political regime or political system. The resurgence of political Islam represents a big challenge to the existing status quo. And also it means that it is a challenge to political systems institutions and their moral and intellectual foundations.  [13]   The context of international relations has been experiencing significant transformations. Many older slogans, paradigms and ideologies that had shaped conceptual frameworks have been discredited or replaced. The collapse of Soviet Union and the end of the Cold War encouraged many to look for and identify new global threats, new enemies and conflicts. For some, political Islam became the next threat and global terrorism. But the realities of Muslim politics reflect a more complex and dynamic reality. The resurgence of religion and ethnicity has been global. Relations between Islam and the West show a process of conflict and change. Islamic jihads and Western clash of civilizations face new realities. Islamically inspired schools, medical clinics,hospitals, social services and financial institutions increased. Islamic parties demonstrated their ability to participate within the system and provide a political alternative to the regimes.Ä ±slamic activists served in cabinets became prime ministers and presidents.  [14]  The terrorism of 11 September highlighted the importance of the struggle within the Muslim world between the violent jihadist vision and the visions of pluralism and dialogue.  [15]  

Analysis of The One Minute Manager by Kenneth Blanchard and Spencher Jo

Analysis of The One Minute Manager by Kenneth Blanchard and Spencher Johnson The One Minute Manager by Kenneth Blanchard, Ph.D. and Spencer Johnson, M.D., seems like a practical simple plan on managing people and there for other areas of one’s life, however I must admit I am a little skeptical. The three philosophies do make sense especially once analogies are used to put them into more simple terms. Being in the work force for more than fourteen years I have witnessed many types of mangers. I have worked for hostile managers, calm caring managers and managers who fit somewhere in between. My skepticism with this theory is simply applying its use. On paper this method sounds great and makes a lot of key points, but again after seeing first hand the types of people in management positions I think the challenge comes from undoing current behavior. My observation of people in general, is that they unwelcome change and find it uncomfortable. The first philosophy â€Å"One Minute Goal Setting† makes tasks assigned to the individual clear and precise. The manager first expresses goals that need to be accomplished. Once an agreement is made, each goal is written down in 250 words or less. It is strongly held that it should take no more than a minute to read. You should reinforce each goal throughout the day. Also take time to look at your performance and see if your behavior matches your goals. I agree with this theory and think there should be more interaction at the beginning of an assignment. With One Minute goal setting everything is out on the table. There is no dispute on what should have been done or didn’t get done. The bowling analogy used has a lot of truth to it. If there were a sheet in front of the pins with a supervisor standing behind it, it would be hard to tell how well your doing because you can’t see the pins or goal. Only the supervisor knows your score. I see this a lot in staff meetings. There are usually conflicts between my manager and staff because of misunderstandings on the task assigned. This is where the conflict resides. The employee feels they did exactly what was asked while the employer thinks the job was done incorrectly. This usually causes my boss to criticize the work and most if not all people take it personally. Then, once the meeting is over, my peers will get defensive and complain t... ...my relationships with family, friends and loved ones I have a habit of not dealing with disappointing feelings right away because I don’t want to cause conflict. My feelings begin to fester and I become more sensitive to other things that normally wouldn’t tick me off, but do, because I am still upset about the first problem. Before you know it, I blow up and everything comes out anyway. Usually the person I am upset with has to hear about what they did a month ago and everything in between. This puts that person on the defense and nothing really gets accomplished until a few days later when we all calm down to discuss the issue. So logically if I dealt with my feelings in the beginning, the blowouts could be avoided and I could calmly get my point across with little conflict. Overall the â€Å"One Minute Manager† concept seems like a dynamic way to keep employees happy and content in their jobs. In my opinion, I think the theory appears too good to be true. I am skeptical because managers would need to struggle with changing their current behavior. I think for me to be convinced that this would work in the real life of business, I would need to experience it first hand.

Chicanoism Today :: essays research papers

Chicanoism Today   Ã‚  Ã‚  Ã‚  Ã‚  For a more symbolic meaning of the word Chicano/a, to many of us it is the mixture of both American and Mexican culture. It had become a political term for those who wanted to find a more specific word to identify themselves with than Hispanic, a word to classify all who spoke Spanish in America from Latin America. In the 60s the word Chicano/a grew strong with many political Mexican-American’s and used it as a source of pride. Today, the older generation of Chicano/as’, some but many, see young Chicano/as’ as those who live in the past or use the pasts’ struggle to reflect on their own lives and go no where to empower their society. For the most part I disagree, I understand and I am grateful for what the older Chicano/as’ have done historical for us newer generations of Chicano/as’ but I resent that I’m labeled as a â€Å"wannabe†. In the definition of what it is to be the newer race of Chicano/as’ I will have to interpret it from what the past has led us to be now.   Ã‚  Ã‚  Ã‚  Ã‚  In many historical moments of the 60s, you could find many racial groups emerging for their rights to liberation from oppression. The Chicano/a movement was certainly one you couldn’t miss in the books. Organizations like the United Farm Workers or the Brown Berets, as well as protests and rallies such as, pro-Affirmative Action, helped in glorifying the meaning of Chicano/a power. It made many Mexican-Americans proud and not alone in a country that didn’t want them there. Yet with such an upraising in praise and pride for this new identity, the movement declined gradually throughout decades to come. Not much political activism had gone on but the word Chicano/a carried on but not in the sense that the Chicano/as of the 60s intended it to be. It would become an identity to those born in America of Mexican parents.   Ã‚  Ã‚  Ã‚  Ã‚  By this time around, now in the 90s, I could have the choice on any application to indicate, optionally, what ethnicity I am. It was either Latino/other, or Mexican/Mexican-American/Chicano. With my parents consent of what I was, I’d proudly pick the box that had Chicano beside it. I grew up proud being Chicana because my dad always had pride in what he was, Mexican. Now, as I write/say this, it isn’t pride so much but honor. I honor being Chicana for what the past Chicano/as’ have done to be recognized but now, I honor what the newer Chicano/as’ will do for themselves and society.

Marketing strategies, tactics, and techniques: A handbook for practitioners Essay

Psychological marketing Introduction   Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚   In a broad spectrum, there are different techniques that are used by sellers, marketers as well as the entire production companies to market their products as an endeavor to lure customers towards their side. One of those techniques is known as â€Å"Other-enhancement†. Essentially, other enhancement is one of the techniques that is used by the advertisers to make consumers or the targeted audience have positive attitude towards them. It is mostly done to perfection through gratifying them and is elemental in some of the product promotion endeavors as a means of advertisement.   Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚   As a matter of fact, the advertisers use exaggeration in portraying the positive side of the company in a bid to make customers to prefer working with them. For instance, Travel Company tries to sell tickets and uses the comments in commercial, â€Å"you deserve this, because you work hard.† When the customers read and analyze the comment, they feel recognized and their hard work recognized in the bid to make the company happy, they end up buying more goods or services as a means of awarding them.   Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚   According to the L’Oreal, the cosmetic company technique of advertisement in the ad, Other-enhancement proves to be key as the company creates new red rouge. Inherently the advertisement uses other-enhancement technique to emphasize the unique characteristics of every woman, saying â€Å"rouge as unique as you are.† This makes customers feel different and special from others and at the same time, the company relates their unique feature of product relates to every woman’s uniqueness. â€Å"Your lips deserve more than just color â€Å"Tailored just for you and your smile, because you are worth it† creates the value of self-recognition. Here, the company shows the specialty of a commodity even if in the real sense it is not. The items value is exaggerated to catch the attention of the customers and make them buy their goods. L’REAL, uses words â€Å"enhancing luxurious feel† to sell their makeups us ing this technique.   Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚   In summary, most companies employ the psychological selling techniques as discussed. L’OREAL employs such methods to make their sales. The goods being sold are not as valuable as they are made look. The sellers play with the minds of potential buyers to trap them and make them buy their items. This marketing technique is adopted by most of the selling companies to promote the stock clearance. References Dobkin, J. (2008). Direct marketing strategies. Merion Station, PA: Danielle Adams Pub. Paley, N. (2008). The Marketing Strategy Desktop Guide. London: Thorogood. Rogers, S. C. (2001). Marketing strategies, tactics, and techniques: A handbook for practitioners. Westport, Conn: Quorum Books. Source document

North Renaissance 1400

Patronage in northern Europe is different from the one in Italy. In the early renaissance, main patron in Italy is the Medici family. This big merchant family benefits a lot from the fast development of Italian economy. They spent a large number of funds on art region, promoting the renaissance to expand. However, in the Northern Europe, English and France still fought each other in the Hundred-Year war. Two competing Popes still resided in Rome and Avigon. These conflicts influenced the economic system of Northern Europe so patrons were unable to provide funds as much as the Medici did.Dukes of Burgundy were major patrons of that age. Patrons provided financial supports for artists to create while their requirements also influenced and limited the styles and contents. The art works had prominent features for private use. For instance, Some Dukes preferred furnishings and tapestries so the forms of art were influenced. Small altarpieces became popular as well. Because of the interest s of the patrons, the styles and contents of art work were limited. Oil painting became popular because it could facilitate the exactitude in rendering details.With oil medium, artists created richer color than previously had been ossible, giving their paintings an intense tonality, the illusion of glowing light and enamel-like surfaces. Robert Campin was one of the earliest masters of oil painting. His most famous work is Merode altarpiece, a private commission for household prayer. Oil painting allowed the artist to paint every detail subtly. Jan van Eyck was also an artist who paid much attention on details. He used color to depict the soft texture of hair, the luster of pearls and the flashing of gems.In Italy renaissance, artists focused more on the scientific methods combining color using while artists in Northern Europe tended to depict the appearance. Donor portraits, which meant portraits of the individuals who donated the works, were another form of art pieces in that era. In Jan van Eyck's Ghent Altarpiece, two of the exterior panels depict the donors, Jodocus Wd and his wife. Jan van Eyck was the first Netherlandish painter to achieve international fame. He was the count painter of Philip the Good, Duke of Burgundy.In Italy Renaissance, artists preferred the classical culture and revealed the Greeks and Romes. The sculpture David by Donatello was a good example of their interest. However, in Northern Europe, artists worked more on the religion and bible. For example, Jan van Eyck's Ghent Altarpiece was about the bible. Dirk Bouts was a later Flemish painter. In his â€Å"Last supper†, he did not focus on the biblical narrative itself, but presented Christ in the role of a priest instead.This painting employed single vanishing-point perspective and included four servants in Flemish attire. Hugo van der Goes's â€Å"Portinari Altarpiece† was a rare instance of the awarding of a major commission in Florence to a Flemish painter. Hugo van der Goes was good at the depicting of details and the human character as well. Influenced by the Gothic style, Northern European paintings were more realistic while Italian paintings were more naturalistic. Matthais Grunewald was German Renaissance painter.His works focused on religion, but they also had specific meanings for viewers. In his work â€Å"Isenheim Altarpiece†, Grunewald presented his altarpiece's iconography to be particularly meaningful for viewers at Isenheim hospital. The painting depicted Bosch was the most famous Netherlandish painter. Bosch was the most imaginative and enigmatic painter of his era. Scholars cannot find a universal interpretation of his work â€Å"Garden of Earthly Delights†. This was similar to Leonardo's â€Å"Mona Lisa†. They were both mysterious.But the content should be more similar to Raphael, who did more on humanism. Albrecth Durer was a dominant artist in Holy Roman Empire. His style was more similar to Leonardo. Lik e Leonardo, Durer also did much research on perspectives and the ideal in human proportions. In short, Northern Europe Renaissance occurred after the Italy Renaissance, but it developed its own styles rather than imitate Italian style simply. Due to the regional differences, various styles and cultures made the Renaissance era rich and colorful.