Managing Human Resources Essay Example | Topics and Well Written Essays - 4000 words

Managing Human Resources - Essay Example As a work motivational approach, Cummings and Worley (2009, p. 434) explained that rewards can either be intrinsic or extrinsic by nature. In line with this, intrinsic rewards include the use of sincere acknowledgement for a good performance whereas extrinsic rewards can be in a form of increased salary, stock options, work promotion, or bonus given to employees (Cummings and Worley, 2009, p. 434). As compared to the use of extrinsic rewards, it is easier to implement intrinsic rewards because HR managers can easily make it a habit to acknowledge the effort of each employee in making the organizational goal attainable rather than requesting the business owners and board of directors to increase the available fund which can be use to reward employees for any improvements in their work performance (Shamir et al., 1993). According to Pfeffer (1998, p. 110), HR managers often ask the question â€Å"how much to pay employees† or â€Å"how much compensation package should be includ ed in the company’s reward system† in order to increase the work performance of each employee. Pertaining to the importance of developing and implementing effective pay and reward system, this report will focus on discussing how internal factors (i.e. organizational vision and mission, organizational structure, organizational culture, business objectives and business strategies) and external factors (i.e. competitors’ pay and reward system that is heavily influenced by economic pressures, the current labour market condition, government implemented labour policies, legal issues concerning the basic labour requirements, and the global labour environment) could shape the organizational approaches when designing a business organization’s pay and reward system (Heneman, Fisher and Dixon, 2001; Zingheim, Ledford and Schuster, 1996). Based on the research findings, the researcher will analyze how each factor is link with the other identified factors when designin g pay and reward systems. Internal Factors that Shapes the Organizational Approaches when Designing Pay and Reward Systems Several research studies revealed that internal factors that could significantly affect the shaping of organizational approaches when designing pay and reward systems includes the organizational vision and mission, organizational structure, organizational culture, business objectives and business strategies (Heneman, Fisher and Dixon, 2001; Zingheim, Ledford and Schuster, 1996). Depending on organizational vision and mission, organizational structure, business objectives and business strategies, a business organization can develop a culture with regards to its accepted and widely practiced pay and rewards system. Communicating the organizational vision to the rest of the employees serves as a guide in the development and implementation of strategic planning. In line with this, a shared vision can be use as a guide in developing the kind of reward system which co uld effectively motivate each employee to improve their work performance (Worldatwork, 2007, p. 39). Upon analyzing the significance of organizational vision and mission in the designing of pay and rewards systems, it is necessary for HR managers to be familiar with the organizational

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.

Tibetan Oracles: Fact or Fiction? :: Tibet Oracle Oracles Essays

Tibetan Oracles The miraculous feats of the Tibetan oracles are well known sources of mysticism. Stories of men who can bend metal swords with their bare hands, dance wildly and proclaim the future have piqued the curiosity and fascination of many. However, most rationale people will question, how real is the Tibet oracle? Are these men really visited by the deities who they claim to be visited by or are they merely masters of illusion? â€Å"The desire to know the future is probably as old as the human race. Early cultures all over the world have left fragments of evidence telling us that divination was of paramount importance in their daily lives.† (Housdan, 7) This desire causes most Tibetans to fervently believe in the power of these oracles. Like most other cultures, the Tibetans are curious about the future and use the methodology of the Oracle as a means for divination. The Tibetan oracles are highly respected members of the community whom the Tibetans consult to find out the future of their own lives as well as the future of the Tibetan country. Despite the Tibetan’s belief in the spiritual nature of the trance, anthropologists who have studied it have been able to come up with other explanations for the trance state that do not involve the religious belief in spirit possession. These explanations often involve subjects such as psychology and neurology that look at the physiological state of the body during the trance. Through scientifically analyzing the trance state, it raises the question of whether or not the oracles who enter into these trances are able to do so intentionally and if an oracle can willfully enter into a trance, then how does an oracle become valid? The Tibetan oracles are both sources of mysticism but they have also been sources of great controversy in Tibet for these questions involving the authenticity of the oracle. The traditional Tibetan belief is that Tibetan deities will take possession of men or women in society who act as mouthpieces of the gods. â€Å"Spiritual possession is defined as an altered state of consciousness that is characterized by desertion of a person’s original personality, followed by temporary replacement of another.†(AvRuskin, 286) The god enters into the body of the medium and the medium will enter a trance-like state during which the deity is using the mediums body as a tool. Tibetan Oracles: Fact or Fiction? :: Tibet Oracle Oracles Essays Tibetan Oracles The miraculous feats of the Tibetan oracles are well known sources of mysticism. Stories of men who can bend metal swords with their bare hands, dance wildly and proclaim the future have piqued the curiosity and fascination of many. However, most rationale people will question, how real is the Tibet oracle? Are these men really visited by the deities who they claim to be visited by or are they merely masters of illusion? â€Å"The desire to know the future is probably as old as the human race. Early cultures all over the world have left fragments of evidence telling us that divination was of paramount importance in their daily lives.† (Housdan, 7) This desire causes most Tibetans to fervently believe in the power of these oracles. Like most other cultures, the Tibetans are curious about the future and use the methodology of the Oracle as a means for divination. The Tibetan oracles are highly respected members of the community whom the Tibetans consult to find out the future of their own lives as well as the future of the Tibetan country. Despite the Tibetan’s belief in the spiritual nature of the trance, anthropologists who have studied it have been able to come up with other explanations for the trance state that do not involve the religious belief in spirit possession. These explanations often involve subjects such as psychology and neurology that look at the physiological state of the body during the trance. Through scientifically analyzing the trance state, it raises the question of whether or not the oracles who enter into these trances are able to do so intentionally and if an oracle can willfully enter into a trance, then how does an oracle become valid? The Tibetan oracles are both sources of mysticism but they have also been sources of great controversy in Tibet for these questions involving the authenticity of the oracle. The traditional Tibetan belief is that Tibetan deities will take possession of men or women in society who act as mouthpieces of the gods. â€Å"Spiritual possession is defined as an altered state of consciousness that is characterized by desertion of a person’s original personality, followed by temporary replacement of another.†(AvRuskin, 286) The god enters into the body of the medium and the medium will enter a trance-like state during which the deity is using the mediums body as a tool.

Guava Extract Soap Essay

Significance In finding a cure for the said problem, we conducted a research and we found out that there are natural compounds that can contribute in treating these kinds of problem. Natural compounds that are used for making soap are more appropriate than chemical-based products. I. Introduction II. Abstract III. Statement of the Problem This study determined the effectivity and practically of 4 Season Fruits in making a homemade facial soap. It sought to answer the following questions: IV. Hypothesis The researchers hypothesize that the product, Four seasons soap, can be a viable alternative to the ordinary facial soap in treating different types of skin problems including acne and pimples due to its â€Å"4 seasons† fruits component. â€Å"Effectiveness of 4 Season Fruits as a treatment for pimples and acne.† Sacred Heart Catholic School of Cainta Investigatory Project Nowadays, having pimples and acne is a common problem for teenagers and adults aside from growing of their facial hair, eye bags and the like. This is due to exposure from dirt, dust, pollution and many agents that can produce skin reaction and form pimples and acne. These natural ingredients namely: Pineapple ( (Ananas Comosus), Mango (Mangifera Indica), Guava (Psidium Guajava) and Orange (Citrus Sinensis) (commonly called as 4 Seasons). These fruits have healthy benefits for the skin and some of their common effect are for treating pimples and acne. Is the component of the 4 Seasons soap is effective as an alternative treatment for skin problems? Is it an effective treatment for pimples and acne? What are the possible effects of 4 Seasons soap for the skin? Since it is a homemade soap, Is it possible that an individual can create soap just like this easily and safely? Our investigatory project focused in different benefits that can heal skin problems due to daily exposure to pollution, dust and other agents that can contribute to similar skin problems. These fruits have healthy benefits for the skin and some of their common effect is for treating pimples and acne. We researchers have guessed that the 4 seasons fruits are effective in treating pimples and acne because it contains Vitamin C which has antioxidant properties. But since it is a homemade soap, is it possible that an individual can create soap just like this easily? The possible effects of the 4 seasons soap are: Cleansing,  Moisturizing, Exfoliating and Clearing pimples and pimple marks. The researchers believed that because of the most of the components can be found at home, It is possible that any individual can make their 4 seasons soap easily and safely if they just follow the steps carefully and faithfully. To recognize all the healthy benefits of each of the four seasons for the skin. To determine if the 4 season soap is an effective antioxidant and its anti-aging properties. VII. METHODOLOGY MATERIALS: PROCEDURES: VI. Scope and Limitation Scope The study was conducted to reveal some of the advantages and disadvantages of the 4 season fruits for making soap as treatment for some major skin problems. The study aims to prove that not all chemical-based soaps are used in treating pimples and acne. The study concentrates on how fruits( Pineapple, Mango, Orange and Guava) can benefit human skin. Limitation The study is limited in human skin problems. 3 tbsp. Oil 1/2 tbsp. Guava leaves extract 1/2 tbsp. Mango extract 1/2 tbsp. Orange extract 1/2 tbsp. Pineapple extract 1 tbsp. NaOH or Lye 3 tbsp. H2O or Water Tools Used: Bowl Soap Molder Sauce pan Spoon Stirring rod Rubber gloves Masks Plastic cups Prepare the things to be needed. First, get the extract of each fruit ( Guava, Orange, Mango & Pineapple) . Note: For the Guava, We will be using the leaves for the extract. FOR THE EXTRACT: Remove the peelings of the fruits, and then set aside. In a small pot, put the peelings of each fruit (Note: Separate the peelings of each fruit from another fruit. Don’t combine it with other fruits when getting extracts, it might have different chemical reaction). Then Add water with this amount: 10 tbsp. for peelings of 3 mangoes. 13 tbsp. for the peelings of 5 oranges. 15 tbsp. for the peelings of 2 pineapples. 15 tbsp. for the guava leaves. Prepare the stove to be used. Boil it for 10 minutes (Low Heat); Separate the skin from the extract. Put it in a clean container, let it cool and then set aside. Prepare the Sodium Hydroxide (NaOH) or Lye. Put in a container. (Note: Read first the directions in using Lye. For Example: Don’t put the NaOH on aluminum containers. You must use rubber gloves and Masks in dealing with lye and with other chemical substances. Don’t play with them and Keep out of reach of children.) Put some oil (3 tbsp.) and Water (3 tbsp.). Mix it thoroughly. Put the extract of the fruits to the mixture. (1/2 tbsp.). Stir the mixture continuously in a single direction. ( Note: Make sure the mixture is viscous) Let it dry for about 2 days or more. VIII. FINDINGS & RESULTS The researchers found out that the 4 seasons fruits can help minimize pimples and pores. It can also help clear skin impurities because of the anti-oxidants that the soap contains. This research gave us a hard time because there are a lot of instances that the measurements of the ingredients would not compliment the desired results. There can also be a downside in this experiment because the soap is not intended to be used in scars because it might irritate it and it stings. IX. Conclusions The researchers therefore conclude that the 4 seasons soap can reduce pimples and other skin impurities. This is shown by the experiment that we conducted by putting various kinds of ingredients in different amounts and sizes. The experiment was successful because the researchers came up with their desired result even after several tries. This product can be a solution in the problem of many teenagers, including the researchers because of its effectiveness during our experiment. X. RECOMMENDATION The researchers recommend that the further experiments similar to this that will be performed by others must use variety of fruits and not just focus on the 4 seasons used in this experiment. It is also suggested that they test the product before producing to help decrease the chances of having skin irritations and rashes. If given a chance, the researchers suggest that they test it on animal skins that are most likely to be similar to the human skin in order to have a possible result as how it would be on the human skin. The researchers hopoe that you may have a successful study and an imporved product in the future.

Bluetooth Technology

Technology already tracks or monitors animals, people, vehicles and other objects to eliminate the need for constant human observation. These technologies need to be small, economical and consume a minimal amount of power. Bluetooth technology is being used extensively in hand-held devices and wireless computing [Pico Communications] because of its characteristics mentioned above. This project aims to use Bluetooth technology to monitor and track animals in the wild. More specifically, this project deals with the off-loading of data from a device situated on an animal. The aim of this literature survey is to investigate the Bluetooth technology, focusing on routing in Bluetooth networks, as well as current animal tracking and monitoring technologies. Current technologies used in tracking and monitoring Many of these projects make use of the Global Positioning System (GPS), Global System for Mobile (GSM) or directional radio transmission tracking. One of them is described in â€Å"Save the Elephants† GSM tracking project, sponsored by Safari. com in Kenya, which makes use of the GPS system to gather locational information of tags placed on elephants [Douglas-Hamilton, I. t al (February 2004)]. These tags also have GSM modules that allow the locational data to be downloaded periodically. Objectives of this project are to develop small tags that have a long battery life, are cheap and light. Before the safari. com project, VHF (Very High Frequency) radio was used to download the GPS data from the animals about every 3 months. Sending data using VHF requires a large amount of power consumption, hence downloads were only done every three months. GSM technology lowers this power consumption enabling more regular data retrieval. Data, such as that elephants usually travel about 10km a day but can walk 30km or more, was collected using this technology. The Kenya wildlife service use this knowledge to plan things like human-animal interaction and fence positioning. A company called Digital Angle has developed a chip that is embedded into animals [Hostetter, J (April 2003)]. While these chips do not produce locational information, they enable a person to electronically identify an animal as well as get its current body temperature. The company is looking at using these â€Å"bio chips† to track an animal's blood pressure and hormonal changes [Hostetter, J (April 2003)]. The bio chips are very small and light but data can only be collected with a hand held reader which provides the chip with power via magnetic induction, similar to RFID technology. Most animal tracking projects are interested in the movements of animals. We are interested in the interaction of animals and possibly data concerning individual animals using the technology being developed by Digital Angle. Because we aim to only use Bluetooth technology (and not GPS), an animal's location could be roughly plotted by tagging physical positions, for example watering holes and trees. The tracking and monitoring systems above use VHF or GSM technologies to download data from animals. We want to look at the feasibility of using Bluetooth networks to download this data. Bluetooth is suited to this application because it is small, light and uses a minimal amount of power, whereas GSM and GPS devices have a short battery life and are large and heavy. In an application that does not involve animals, Ron Alterovitz from the computer science department at Caltech University in California has done a research project involving message routing over a Bluetooth scatternet. Alterovitz, R (2001)] His aim was to make wireless-enabled vehicles communicate while in motion. The ad-hoc properties of piconets and scatternets enable the vehicles to pass messages between them while they are in motion. The vehicles were linked up to a positioning system and set to run around in a 1000Ãâ€"1000 cm room. Each vehicle was able to transmit up to a distance of 250cm. The vehicles were left to move around the room randomly while the positioning system and vehicles passed messages amongst each other to stop them crashing. The routing tables, used to pass messages, were only allowed to be updated at set intervals. It was found that message packets were lost if the speed of the vehicles was increased while the routing interval was kept the same [Alterovitz, R (June 2001)]. Although Bluetooth has been used for tracking small autonomous vehicles, there is no evidence of the use of this technology to track animals. However, wireless devices, for example Bluetooth enabled cell phones, could be used to track human beings. This raises ethical and privacy issues [Potter, B (November 2003)]. Bluetooth as the Underlying Technology The above technologies aim to provide a means of tracking or message-passing through the use of devices that are physically small, use minimal amounts of power and support an ad-hoc type of communication. Bluetooth supports realistic data rates of up to 600Kbps and claims to make a battery last from 50% to 300% longer than other wireless technologies [PicoCommunications, (November 2002)]. There are two classes of Bluetooth device. The class 2 radio allows a range of ten meters while class 1 radios allow for transmission over 100 meters. Bluetooth operates in the license-free 2. 4GHz band making use of frequency hopping at a rate of 1600 hops per second. Although Bluetooth has limitations in its transfer speed and communication distance, its market share is rising while 802. 11 (WiFi) has slowed down in its growth [Dursch, A. et all (December 2003)]. The rising interest in Bluetooth will increase production, causing the already cheap technology to become easily obtainable. The Bluetooth stack Illustration 1The Bluetooth Stack Each Bluetooth packet has a fixed format that starts with a 72-bit access code. This is followed by a 54-bit header containing error correction, retransmission and control information. Finally the packet contains a payload of 0 to 2745 bits. Three methods, Forward Error Correction (FEC), Automatic Repeated Request (ARQ) and Cyclic Redundancy Checks (CRC) are used for error correction during Bluetooth communication [Forum Nokia (April 2003)]. This project is interested in the following Bluetooth stack layers: The Link Manager Protocol (LPM) layer is responsible for setting up the links between Bluetooth devices and deals with master/slave switching, low power modes, clock offsets and packet size negotiation. This layer, although not critical to this project, also handles the exchange of authentication and encryption information. The Logical Link Control and Adaptation Protocol (L2CAP) enables multiplexing of the protocols above it by segmenting and reassembling packets [Pico Communications inc]. The Service Discovery Protocol (SDP) enables Bluetooth devices to advertise and discover services. SDP passes bitmasks, representing advertised services, to all backbone nodes. This allows other devices to discover the type and location of a service on a Bluetooth network quickly [Nordbotten, N, A. et al (2004)]. RFCOMM is a serial port emulation protocol enabling RS232 control and data signaling over Bluetooth. It allows services such as the Point to Point Protocol (PPP) to be used over Bluetooth. IP is the standard protocol used on the Internet [Pico Communications inc]. Bluetooth profiles Bluetooth profiles describe the main usage models of Bluetooth. The current Bluetooth specification contains four general profiles. [Forum Nokia (April 2003)] The Generic Access Profile defines the discovery of other Bluetooth devices, link management and connectivity, security levels and common format requirements for user interfaces. All Bluetooth devices have to support this profile and all other profiles require and use it. The Service Discovery Application Profile defines procedures for a Bluetooth application to discover services advertised by another Bluetooth device, and should be followed should this project make use of services during implementation. The Serial Port Profile defines the Bluetooth requirements for setting up emulated serial cable connections. This profile is also an option should this project transfer data over RS232 connections. The Generic Object Exchange Profile is used by applications that need object exchange capabilities. This profile is also an option should we want to model our data as objects and pass these objects from device to device and then finally to a data sink [Forum Nokia (April 2003)]. Ad-Hoc Bluetooth Networks Bluetooth enabled devices form ad-hoc networks when they come into contact with one another. These networks are built using scatternet and piconet formation algorithms as described by [Law, C. et al (2001)]. Between 1 and 7 devices can form a piconet. One device is designated to be the master. This decision is made by each device generating a random number determining whether the device will assume to be the master and seek slaves or assume to be a slave and scan for the master. Because only 7 nodes are allowed to participate in a piconet, scatternets are formed by linking many piconets together via shared slave nodes. The number of piconets to which a device belongs is termed its degree. A master node in a piconet may only have a degree of one, meaning a master node may not be shared between two piconets. The shared slaves are time multiplexed between the piconets to which it belongs and data sent between the piconets must be sent via the shared slave [Law, C. et al, (2001)]. The time it takes for data to be passed through a shared slave is dependent on the manner in which the shared slave switches between piconets. Shared slaves need to have timed rendezvous points with piconet masters in order to exchange data [Misic, J. et al (February 2004)]. The masters and shared slaves are collectively referred to as back bone nodes of the formed scatternet. The piconet and scatternet formation algorithms allow nodes to move and migrate between piconets and allow small piconets to be merged [Law, C. et al (2001)]. These ad-hoc properties of piconets and scatternets enable data to be exchanged between many Bluetooth devices while those devices are moving between piconets within a scatternet, effectively enabling the devices to physically move around while data is being exchanged amongst them. Conclusion This literature search has found no evidence that Bluetooth has been used to track or monitor animals in the wild. It has however found many applications where Bluetooth networks have been used for mobile devices needing to exchange data. The literature shows that there is a need for small, inexpensive animal tracking devices that consume a minimal amount of power. It is also shown that Bluetooth is already being used for hand-held and mobile computing applications for these same reasons. Our aim is to build upon the device and network technologies surveyed in this paper, to determine the feasibility of a Bluetooth-based animal tracking and monitoring system, which has a low degree of human probe effect.

Protists Organisms in the Kingdom Protista

Protists Organisms in the Kingdom Protista Protists are organisms in the kingdom Protista. These organisms are eukaryotes, meaning they are made up of single or multiple cells which all contain a nucleus enclosed by a membrane. The protists are a diverse group of eukaryotes that cannot be classified as animals, plants, or fungi. Organisms in the Protista kingdom include amoebae, red algae, dinoflagellates, diatoms, euglena, and slime molds. How Protists Are Defined Protists are defined by  how they obtain nutrition and how they move.  Protists are typically divided into three categories, including animal-like protists, plant-like protists, and fungus-like protists. Protists vary in how they move, which can range from cilia, flagella, and pseudopodia. In other words, protists move by microscopic hair that flaps together, by a long tail that moves back and forth, or by extending its cell body, similar to an  amoeba. Nutritionally,  protists tend to gather energy in a variety of ways. They can either eat food and digest it inside of themselves, or they may digest outside of their bodies by secreting enzymes. Other protists, like algae, perform photosynthesis and absorb energy from sunlight to make glucose. Animal-Like Protists Some protists look like animals and are typically referred to as protozoa. Most of these types of protists are made up of a single cell and are similar to animals in nature because they are  heterotrophs and able to move around. While they are not considered animals themselves, it is often thought that they may be a shared ancestor. Examples of animal-like protists include: Zooflagellates – flagellaSarcodines – extensions of cytoplasm (pseudopodia)Ciliates – ciliaSporozoans Plant-Like Protists There is also a large and diverse group of protists that are plant-like and known as algae. While some are single-celled, others like seaweed have multiple cells. For example, one type of protist in the marine environment is  Irish moss, which is a species of red algae. More plant-like protists include: DinoflagellatesDiatomsEuglenoidsRed algaeGreen algaeBrown algae Fungus-Like Protists Lastly, there are funguss of fungus-like protists may include: DictyosteliomycotaMyxomycotaLabyrinthulomycotaOomycetes The Benefits to Our World Protists are important to the world in several ways. You may be surprised to learn that chalk is made from the fossil shells of protists, which is helpful in our classrooms and our childrens creativity and play. Additionally, protists produce oxygen which is helpful for the planet. Many protists have a high nutritional value which can help improve illnesses. Protists like protozoa are used in foods like sushi and are good for our water, as protozoa are used to prey on bacteria and help to clean water for us to use.

Free Essays on Descartes Discourse

Descartes' first discussion of scientific method is in an unfinished work of 1628 titled Rules for the Direction of the Mind. The first 12 of the planned 36 rules deal with the general aspects of his proposed methodology, and are considered early versions of principles which made their way into his later writings. In 1633 Descartes prepared for publication a work on physics called Le Monde which defended a heliocentric view of the universe. That same year the Catholic Church condemned Galileo's Dialogue (1632). Descartes did not think Galileo's views were prejudicial to religion and he worried that his own views might be censured. Thus he suspended publication of it. In 1637 Descartes published a collection of essays titled Optics, Meterology, and Geometry. Prefaced to these essays was a work titled "Discourse on the Method of Rightly Conducting the Reason and Seeking Truth in the Sciences." Most of the "Discourse" was written before the 1633 condemnation of Galileo's Dialogue. Howev er, he later added a concluding section which explained that he insisted on publishing, in spite of political risks. The simple reason was that he counted on the public to help confirm his scientific theories. In the Discourse, Descartes offers a method of inquiry quite different from Bacon's. Whereas Bacon advocated induction, Descartes insists on a more deductive approach. Most of the Discourse is autobiographical insofar as it traces Descartes intellectual development and how his method assisted him in his investigations. Descartes realized that he needed to reject much of the teachings of his youth. This raised the question as to exactly how he should proceed in replacing old theories with new ones. He found his answer by observing how old parts of cities are replaced with the new. The more elegant cities are those which are methodically built from scratch, not those which continually renovate old sections. Descartes explains that he had learned a va... Free Essays on Descartes Discourse Free Essays on Descartes Discourse Descartes' first discussion of scientific method is in an unfinished work of 1628 titled Rules for the Direction of the Mind. The first 12 of the planned 36 rules deal with the general aspects of his proposed methodology, and are considered early versions of principles which made their way into his later writings. In 1633 Descartes prepared for publication a work on physics called Le Monde which defended a heliocentric view of the universe. That same year the Catholic Church condemned Galileo's Dialogue (1632). Descartes did not think Galileo's views were prejudicial to religion and he worried that his own views might be censured. Thus he suspended publication of it. In 1637 Descartes published a collection of essays titled Optics, Meterology, and Geometry. Prefaced to these essays was a work titled "Discourse on the Method of Rightly Conducting the Reason and Seeking Truth in the Sciences." Most of the "Discourse" was written before the 1633 condemnation of Galileo's Dialogue. Howev er, he later added a concluding section which explained that he insisted on publishing, in spite of political risks. The simple reason was that he counted on the public to help confirm his scientific theories. In the Discourse, Descartes offers a method of inquiry quite different from Bacon's. Whereas Bacon advocated induction, Descartes insists on a more deductive approach. Most of the Discourse is autobiographical insofar as it traces Descartes intellectual development and how his method assisted him in his investigations. Descartes realized that he needed to reject much of the teachings of his youth. This raised the question as to exactly how he should proceed in replacing old theories with new ones. He found his answer by observing how old parts of cities are replaced with the new. The more elegant cities are those which are methodically built from scratch, not those which continually renovate old sections. Descartes explains that he had learned a va...