Ball Mill free essay sample

CHAPTER 1- INTRODUCTION Ball Mill plays an important role in paint industry. The manufacture of pigmented paint involves the dispersion of the pigments into binder and solvent components. This is an important part in the manufacturing process of paints. For this purpose grinding devices like ball mill, bead mill, sand grinder, roll mill or high-speed grinders are used. Though compared to ball mill the other devices provide better dispersion, they require constant attention, semi-skilled labor, high power requirements and have low rate of production, making the ball mill an important and significant part of paint industry. This report comprises of basic information related to paints, principles of grinding, the use of ball mill in paint industry, factors governing the efficiency of mill and various technological aspects regarding the use of ball mill in paint industry. CHAPTER 2- PAINT 2. 1 Paint It is a coating consisting mainly of resin, a solvent, additives, and pigments. We will write a custom essay sample on Ball Mill or any similar topic specifically for you Do Not WasteYour Time HIRE WRITER Only 13.90 / page It made its earliest appearance about 30,000 years ago. Cave dwellers used crude paints to leave behind the graphic representations of their lives that even today decorate the walls of their ancient rock dwellings [1]. 2. 2 Components of paint Paint comprises of various components. They are as follows: Pigments- Pigments are finely ground particles or powders that are dispersed in paints. They impart qualities such as color and opacity and influence properties such as gloss, film flow, and protective abilities. They can be categorized into two main types: 1. Prime or hiding pigments- They provide whiteness and color. They are also a source of hiding capacity. Eg- TiO2. They also protect the substrate from the harmful effects of ultraviolet light. 2. Inert or extender pigments-Extender pigments or extenders provide bulk at relatively low cost. They impact many properties like sheen, scrub resistance, exterior color retention [2]. Binder- It is the actual film forming component of the paint. It imparts adhesion, binds the pigments together, and strongly influences properties such as gloss, exterior durability, flexibility, and toughness. Binders include synthetic or natural resins such as acrylics, polyurethanes, polyesters, melamine resins, epoxy or oils [2]. Solvent Vehicle- Solvent is used to adjust the viscosity of the paint. Vehicle acts as a carrier for paint application. Usually solvent and vehile are same. The vehile or the solvent is volatile and does not become part of the paint film. It can also control flow and application properties. Its main function is as the carrier for the non volatile components. Eg- water, alcohols, ketones, esters, glycols and ethers [2]. Additives- They impart specific properties like pigment stability, anti-freeze properties and foam control [2]. Misc. Fillers are used to thicken the film, support its structure and simply increase the volume of the paint. Eg-talc, lime. Catalysts, Thickeners, Stabilizers, Emulsifiers, Texturizers, Adhesion promoters, Flatteners (de-glossing agents) are also added [2]. . 3 Important characteristics of paint The important characteristics of paint are as follows [3] :- 1. Hiding or covering power 2. Required color 3. Required sheen or gloss 4. Weather resistance 5. Dirt resistance 6. Blister resistance 7. Resistance to peeling 8. Anti-corrosive properties 9. Proper consistency or viscosity 10. Non-Toxicity 11. Low cost 2. 4 Paint Applications The main purpose of use of paints is to protect products from environmental corrosion and to improve their consumer appeal. The various applications of paint are [1]:- 1. Paints are used as protective coating for equipments and structures in industries. . Paints are used as marine coatings, mainly as coatings to protect new and existing commercial ships or offshore oil and gas rigs and equipments. 3. Paints are used for highway or traffic markings. 4. Paints are used as architectural coatings. 5. Paints are used to protect food and beverages in metal cans from spoilage and contamination. 2. 5 Paint Manufacturing Process The various steps of paint manufacturing process are as follows [4] :- 1. The pigment is mixed with sufficient binder and solvent or vehicle to make a paste, which has the correct consistency for grinding. . The paste is grinded in a mill until the aggregates are broken down, as indicated by the ‘fineness of grind’ test and that the p igment gets dispersed in the paste. 3. After the required dispersion the paste is thinned to the required consistency. 4. Performance enhancers and preservatives are added to improve the properties. 5. Tinting of batch is done to get the required color. 6. Testing is done to determine physical properties and performance requirements. 7. Filling and packing of paints is done. Figure 1 gives a detailed description of the various steps of paint anufacture. Figure 1: Process Flow Diagram of Paint Production[4] CHAPTER 3- GRINDING 3. 1 Grinding Grinding is a unit operation designed to break a solid material into smaller pieces. There are many different types of grinding mills and many types of materials processed in them. Historically mills were powered by hand (mortar and pestle), working animal, wind (windmill) or water (watermill). Today they are also powered by electricity. The grinding of solid matters occurs under exposure of mechanical forces that trench the structure by overcomin g of the interior bonding forces. After the grinding the state of the solid is changed: the grain size, the grain size disposition and the grain shape. As represented in figure 2, grinding, in which size reduction of the particles takes place, can occur in two ways, either by collision or compressive forces between the particles or by rubbing or attrition forces. Grinding may serve the following purposes in engineering: 1. Magnification of the surface area of a solid 2. Manufacturing of a solid with a desired grain size 3. Pulping of resources [5] [pic] Figure 2: Schematic representation of compressive and attrition forces in grinding [5] . 2 Energy and power requirements in grinding During size reduction the particles of feed material are first distorted and strained. The work necessary to strain them is temporarily stored in the solid as mechanical energy of stress. As additional force is applied to the stressed particles they are distorted beyond their ultimate strength and suddenly rupture into fragments and ne w surfaces are created. Every unit area of solid has a definite amount of surface energy, the creation of new surface requires work which is supplied by the release of energy of stress when the particles break [6]. 3. 3 Grinding laws In spite of a great number of studies in the field of fracture schemes there is no formula known, which connects the technical grinding work with grinding results. To calculate the needed grinding work against the grain size changing three half-empirical models are used: 1. KICK for d 50 mm [pic] Equation- 1 According to Kick’s law (in 1885, based on stress analysis of plastic deformation within elastic limits) work required for grinding a given mass of material is constant for the same reduction ratio, that is the ratio of initial particle size to final particle size. 2. BOND for 50 mm d 0. 5 mm [pic] Equation- 2 According to Bond’s law (in 1952) the work required is inversely proportional to the square root of the diameter of the particles. 3. RITTINGER for d 0. 05 mm [pic] Equation- 3 According to Rittinger (in 1867) work required is proportional to new surface created. It also means that for a given material and a given machine the grinding efficiency is indepe ndent of size of feed and product. In all these postulates W is the grinding work in kJ/kg, c is the grinding coefficient, dA is the grain size of the source material and dE is the grain size of the ground material. A reliable value for the grain sizes dA and dE is d80. This value signifies that 80% (mass) of the solid matter has a smaller grain size. To calculate the KICKs and RITTINGERs coefficients following formulas can be used : [pic] Equation- 4 [pic] Equation- 5 with the limits of BONDs range : upper dBU = 50 mm and lower dBL = 0. 05 mm [5] [6]. 3. 4 Grinding degree To evaluate the grinding results the grain size of the source material (1) and of the ground material (2) is needed. Grinding degree can be expressed by various parameters: 1. Grinding degree referring to grain size d80 pic] Equation 6 Instead of the value of d80 also d50 or other grain diameter can be used. Grinding degree referring to specific surface [pic] Equation 7 The specific surface area referring to volume Sv and the specific surface area referring to mass Sm can be found out through experiments [5]. CHAPTER 4- MILLS USED FOR GRINDING 4. 1 Ball mill A typical type of fine grinder is the ball mill. A slightly inc lined or horizontal rotating cylinder is partially filled with balls, usually stone or metal, which grinds material to the necessary fineness by friction and impact with the tumbling balls. The feed is at one end of the cylinder and the discharge is at the other [5]. 4. 2 Pebble mill A rotating drum causes friction and attrition between rock pebbles and ore particles. It can be used where product contamination by iron from steel balls is to be avoided [5]. 4. 3 Rod mill A rotating drum causes friction and attrition between steel rods and ore particles. The rods range from 25 mm to 125 mm in diameter [5]. 4. 4 Tube mill It is a continuous mill with a long cylindrical shell. Tube mills are excellent for grinding to very fine powders in a single pass when the amount of energy consumed is not of primary importance [5]. . 5 Compartment mill When slotted transverse partitions are used in a tube mill then it is called a compartment mill. The compartments have balls of different sizes. One having large heavy balls, the other small balls and another having pebbles. This segregation of grinding media in the various compartments helps in avoiding waste work as heavy balls break on ly the large particles. The smaller ones fall only on the small particles and not on large lumps, which they cannot work [5]. 4. 6 Conical ball mill The feed enters through a 60o cone into the grinding zone where the diameter of the shell is maximum. Product leaves through the 30o cone. Such a mill contains balls of different sizes all of which wear and become smaller as the mill is operated. New balls are added periodically. As the shell rotates the large balls move toward the point of maximum diameter and small balls migrate to the discharge [5]. Figure 3 gives the detailed description of a conical ball mill. Figure 3: Conical Ball Mill [6] 4. 7 SAG mill SAG is an acronym for Semi-Autogenous Grinding, and applies to mills that utilize steel balls in addition to large rocks for grinding. The SAG mills use a minimal ball charge of 6 to 15%. SAG mills are primarily used in the gold, copper and platinum industries with applications also in the lead, zinc, silver, alumina and nickel industries [5]. [pic] Figure 4: Principle of SAG Mill Operation [5] Principle of SAG Mill operation As shown in figure 5, in SAG mill a rotating drum throws large rocks and steel balls in a cascading motion, which causes impact breakage of larger rocks and compressive grinding of finer particles. Attrition in the charge causes grinding of finer particles. SAG mills are characterized by their large diameter and short length. The inside of the mill is lined with lifting plates to lift the material inside up and around the inside of the mill, where it then falls of the plates and falls back down. 4. 8 Autogenous mill A rotating drum throws large rocks in a cascading motion, which causes impact breakage of larger rocks and compressive grinding of finer particles. It is similar in operation to a SAG mill but does not use steel balls in the mill. Attrition in the charge causes grinding of finer particles. It is also known as ROM or Run Of Mine grinding [5]. CHAPTER 5- USE OF BALL MILL IN PAINT INDUSTRY 5. 1 Role of ball mill in paint industry The manufacture of pigmented paint involves the dispersion of the pigments into part of the binder and solvent components. This is the key component of the manufacturing process. For this various grinding devices like balling mill, bead mill, sand grinder, rolling mill or high-speed grinder are used. As compared to ball mill though the other devices provide better dispersion but they require constant attention, require semi-skilled labor, require high power and have low rate of production [7]. 5. 2 Ball Mill The ball mill is a horizontal cylindrical vessel, which is used for size reduction. It can reduce size of a particle upto one-tenth of a micron. It rotates about a horizontal axis. It is partially filled with the material to be grounded and the grinding medium. The various advantages of a ball mill are: 1. It is a well-established technology. 2. It is a simple technology not requiring many moving parts. Hence it is a robust construction. 3. It is possible to recirculate the ground material and achieve finer grinding. It is also possible to regulate the amount of recirculated product to control the final product. 4. Apart from grinding ball mills are also used for mixing. . By using different media in the same drum we can process wide variety of feed [8]. 5. 3 Applications of Ball Mill in paint industry The applications of ball mill in paint industry are as follows [9]: 1. Ball mills are used for reduction of size of pigments. 2. They are used to make pigments uniform in the finished product. 3. They are used for grinding inexpensive coarse extender pigments in the batch, which gives more hiding power. 4. In case of agglomerated pigments resulting from storage and handling, ball mills are used. Steel ball mills and pebble mills are sed in the paint industry. CHAPTER 6- STEEL MILL PEBBLE MILL 6. 1 Pebble Mill The pebble mill can be obtained in various diameters and lengths with almost any capacity desired. The ends or heads of the mill are usually cast iron and the shell is steel. The inside of the cylinder is lined with either porcelain or stone (Silex or French Buhrstone). A shaft extends from center of each head. These shafts ride in very heavy bearings supported on trunions or legs, which can be mounted either on the floor or from the ceiling. The machine is suspended in a horizontal plane. A charging gate is located on one side of the cylinder with a grilled discharge valve on the opposite side. Removable plug is provided in one end for taking the samples. A large ring gear of the same diameter as the mill is bolted to one end of the cylinder for rotating. The grinding charge consists of porcelain balls for the porcelain-lined mills and flint pebbles for stone lined mills. These mills can be used for grinding white gloss and semi-gloss enamels or house paints. The advantage of pebble mill is that there is no discoloration of products because the components do not contact any metal surface. The diameter of the cylinder should be large enough to allow proper cascading of pebbles or balls of proper size when the mill is rotated [7]. Figure 5 shows a photograph of pebble mill, provided by Paul O Abbe Inc. 6. 2 Steel Ball Mills Steel ball mills operate on the same principle as pebble mills but they are jacketed for water-cooling. The shell is made of chrome-manganese steel. The grinding charge is usually composed of chrome-manganese steel balls that are 5/8 in. in diameter. This tough and hard metal is used to reduce wear and minimize discoloration. Water cooling jackets are necessary to remove heat generated by contact of metallic surfaces when the mill is in operation. Fine grinds and better dispersion are usually obtained with ball mills in a much shorter time than with the pebble mills, as the steel balls are heavier and of higher density as compared to flint pebbles or porcelain balls. Hence small size balls can be used thereby providing more grinding contacts for each revolution of the cylinder. However they cannot be used for white or light colored paints as abrasive action of steel on steel can produce free iron to discolor the light colored batches. The discoloration is not significant in case of darker colors. Apart from this steel mills can’t handle materials affected by metallic contamination [7]. Figure 6 shows a photograph of steel mill, provided by Paul O Abbe Inc. Figure 5: Pebble Mill [10] Figure 6: Steel Mill [10] 6. 3 Essential features of Ball and Pebble Mill The essential features of ball and pebble mill are as follows [7]: 1. They are simple to load and unload. 2. They can be operated by unskilled labor. 3. These mills do not require premixing of paste. 4. They can be run during off-peak loads and hence they are economical to operate. 5. They are well suited to continuous batch grinding of the same pigment, hence excessive cleaning between the batches is avoided. 6. They require no attention during operation, hence can be loaded in the afternoon and run overnight and can be unloaded in the morning. 7. However in 24-hour operation, four hours are required to load and unload a mill. 8. If the mill is run for more than one day, it is run for even days plus the original 20-hour interval. 9. They are well suited to continuous batch grinding, hence avoiding excessive cleaning between the batches. . 4 Types of grinding media used in Ball or Pebble Mill There are three types of grinding media that are most commonly used: 1. Flint Pebbles 2. Porcelain Balls regular and high density 3. Steel and other metal Balls Flint Pebbles These are the oldest type of grinding media in use. They can be used with all types of lining and even in the chrome manganese mills. They are exceptionally tough and longwearing and last for many years regardless of the kind of service. Porcelain Balls This is a pure white ceramic material with a dense, highly vitrified body that does not chip or crack in service. High Density Media This is another grinding media developed for ball and pebble Mills. They are made with a high alumina oxide content and have a density 40 to 50% greater than the regular porcelain balls. They are also fired at higher temperature making them harder and more abrasion resistant. High-density media are available in various shapes including spheres, cylinders and ovals resembling the natural flint pebbles. It is advantageous to use high density grinding media when the product is hard to grind and requires all the energy available to break it down or where higher viscosities can be developed as in the case of paint industry. Steel and other Metal Balls Steel balls are used for faster grinding job than any of the other commercially available media. They are especially valuable in the paint industry. The following metals are used to make balls, which are commonly used in ball mills: 1. High carbon high manganese steel with alloying elements or molybdenum, chromium or nickel. 2. Cast Nickel Alloy 3. Stainless Steel 4. Chilled Iron 5. Forged Low Carbon Steel 6. Other more special types include bronze or brass, aluminum, tungsten or carbide [9]. 6. Linings used in Ball or Pebble Mill The various linings, which are used in ball or pebble mill are as follows: Burrstone lining- It is a pure flint lining, noted for its exceptional durability. It is one of the toughest lining materials available for Pebble Mills. Burrstone lined mills can run for a continuous production schedule for more than 25 years without repairs. Apart from its exceptional wearing quality, Burrstone has a natural rough surface, which help s prevent the charge from sliding or slipping thereby insuring a more efficient grinding action. Porcelain lining- This is a pure white ceramic lining which has a dense, tough structure especially developed for Pebble Mill service. It can stand up for many years under the most severe kind of service and is highly recommended where requirements call for a white lining. High density porcelain lining– It is made with a high alumina content, it is the toughest and most abrasion resistant of the synthetic linings and under normal conditions, it will outlast the standard porcelain lining several times. Metal linings- The cylinders of batch type steel ball mills are usually made of abrasion resistant alloy steel like chrome manganese. Apart from this, linings of other metals like chilled iron, manganese, high carbon, stainless steel, bronze can be also used [10]. 6. 6 Operations of Pebble or Ball Mill The various operations of pebble or ball mill are as follows [7]: 1. The pigment and a predetermined portion of the vehicle are placed in the mill. 2. First the liquid or the vehicle is loaded followed with the pigment as it gives better initial wetting and there is less danger of ball formation. If the pigment is loaded first it prevents liquids from penetrating through the pebble voids and makes the mill more difficult to load and an extra session of spinning of mill might be required. Sufficient vehicle should be put into the mill to come just to the top of the ball level. 3. After loading, the mill is then revolved. Loading and discharge closures are checked to ensure that they are tight and do not leak. At the end of the run time (predetermined by number of hours or revolutions required) a sample of paste is checked for fineness of grind. Grinding gauges are used to test the degree of fineness of grind. Removable plug is used to take the sample. If the fineness is not satisfactory the mill is operated for longer time until the correct degree of dispersion is obtained. 4. The mill is then stopped and enough of the remaining vehicle is added to produce a consistency suitable for discharging the ground paste from the mill. 5. The mill is closed again, rotated for 15 to 30 minutes to ensure uniform mixing and then the slurry of paste is discharged either by gravity or by means of pumping device. When pumping is used, the suction line may be attached directly to the discharge valve or cover. A safety screen is provided to prevent damage to the pump by a pebble or ball chip, which might be sucked through the discharge grate by the pump. The vent plug should always be removed so that the pump may do its work without being hindered by the vacuum, which would build up in the mill if the vent were left closed. When blowing, the air line is connected to the vent opening and the air pushes on top of the material forcing it out the discharge opening. 6. When the charge has been removed a portion of the thinning vehicle is put in the mill, which is then closed and rotated again. This is used to wash the mill. 7. The pebble or ball charge is to be periodically checked to ascertain if the correct volume of grinding medium is present and to check for the wear of the pebbles. At least once a year the pebble charge is unloaded from the mill and the pebble or the balls are screened and those who are badly worn, broken, defective or are undersized are replaced. In order to have daily production of 2000 gallons of paste product the following equipments are used: 1. Two 13 x 32 in. high-speed mills each equipped with a 25 hp explosion proof motor. 2. One 13 x 32 in. roller mill equipped with a 20 hp explosion proof motor. 3. One 4 x 5 ft Buhrstone lined pebble mill equipped with a 10 hp explosion proof motor. One 3. 5 x 4 ft chrome manganese steel ball mill equipped with a 10 hp explosion proof motor [7]. 6. 7 Grinding Mechanism The working of pebble and steel ball mill depends on the movement of stone or porcelain pebbles or steel balls within revolving cylinders for dispersion of dry pigments in liquid vehicles. Each mill rotates at such a rate of speed that the pebbles or balls are carried up on the side of the cylinder by centrifugal action, but at a speed that enables the force of gravity or the centripetal force to overcome the centrifugal force and allow the pebbles to fall and cascade over each other. The balls or the pebbles break contact from the wall at the â€Å"angle of break†. Thus the material, which is being grounded, is subjected to crushing by impact of pebbles on pebbles and by slipping or rolling of pebbles against each other and the lining of the cylinder. This process is continued as long as is necessary to obtain the desired degree of dispersion. The speed of rotation should be less than critical speed. At critical speed centrifugal force is so high that balls are carried over. No grinding takes place the mill is said to be centrifuging [7]. Figure 7 gives the pictorial representation of the various forces and the directions in which their components are acting on a particle in a ball mill operation Figure 7: Forces acting on a particle in a ball mill operation [6] 6. 8 Slip in Ball or Pebble Mill The term â€Å"slip† means relative motion between the layer of grinding media nearest the lining and the surface of the lining itself. Slip may be caused by several factors: 1. A smooth inside surface on the lining 2. A low viscosity batch of material 3. Material with a very low co-efficient of friction 4. A very light weight charge of grinding media and material. The effects of slip are detrimental to efficient and economical grinding. The angle of break drops sharply when excessive slip occurs and as a result, the grinding media break away from the periphery of the mill too soon, thereby developing less grinding energy. The grinding time and power costs increase considerably. Some grinding does occur between the shell and the grinding media, but this action is considerably less than that which accompanies the rolling, cascading, sliding, and relative motion in the center of the charge which occurs when the correct angle of break is maintained. Hence it is important to have a correct angle of break to have proper dispersion. The most detrimental effect of slip is that the grinding media in contact with the lining slide around the entire weight of the charge forcing them down onto the lining. As a result the mill interior becomes full of ruts and ridges and wears away very rapidly. Then the lining has to be replaced which is costly, time consuming operation. Apart from this the wear on the lining results in excessive batch contamination. Slip is most prevalent in steel ball mills but it can also create a problem in porcelain-lined mills. To prevent it burrstone lining, with rough surface can be used to prevent the slip problem. In some cases, where slip occurs, it can be removed by increasing the viscosity of the batch. However mechanical means of controlling the slip known as baffle bars are usually used. In steel ball mills baffle bars are made of special, chip -proof, hardened steel. In porcelain -lined mills the baffle bars are made of high-density material. The bars are spaced equally in a horizontal position around the inner circumference of the lining. The quantity used is dependent upon the diameter of the mill and the type of operation involved. They project above the inside lining surface just enough to prevent the first layer of grinding media in direct contact with the lining from slipping backwards on the smooth lining while the mill is turning. Baffle bars with relatively, flat sides are more effective than any other design. The flat sides secure the maximum locking effect along the cylinder wall with the first layer of grinding media held stationary relative to the lining surface until they reach the angle of break. Backward slipping of the media and material is completely eliminated. The outer edges of the baffle bars in contact with the media charge should be smoothly rounded to prevent excessive wear and chipping [10]. The figure number 8 shows the principle of slip, angle of break and the use of baffle bars in a ball mill. pic] Figure 8: Angle of Break, Principle of slip baffle bars [7] 6. 9 Jackets The use of a jacket on a ball or pebble Mill makes possible the control of the batch temperature while the mill is in operation. If mill temperatures are too low, many products will run at much higher viscosities than are recommended. This would lead to slow grinding time. If mill temperatures are too high, lower viscositi es will usually result. This causes excessive wear on linings and grinding media and therefore batch contamination. Another danger of grinding at high temperatures is that of pressure buildup. The jacket is usually fitted around the cylindrical shell only, but it can be also extended to enclose both ends of the mill according to the situation. Fluids as hot water, steam, or hot oil pass through the jacket and maintain the fluid consistency. Cold water or brine passing through the jacket, maintain cool temperatures while grinding. Cooling is necessary for paste production in the mill in paint industry [10]. 6. 10 Venting and pressure in mills The vent plug in the head of the mill has two primary functions: 1. It aids in the loading and discharging of the mill. The use of a vent helps in loading of the liquids in the batch. During unloading, the vent plug should be removed before the cover or discharge valve is opened. The vent permits more rapid discharging. The vent plug is removed so that the pump can discharge the material from the mill without being hindered by the vacuum, which would build up in the mill if the vent were left closed 2. The second use of the vent is for reducing pressure, which may build up in a mill during operation due to volatile liquids or heat being generated in the mill. Ball and Pebble Mills are not normally built for pressure operation. Therefore it is important to make certain there is no excessive pressure built up during the grinding cycle, to avoid damage to the mill end and lining. Special care should be exercised when grinding volatile solvents, as these are most apt to cause high pressures if heat develops while grinding. The mill is vented about one -half hour after starting a new batch and it is followed with such periodic ventings. Periodic venting to prevent pressure buildup has resulted in increased grinding efficiency. It is possible in many cases to withdraw air from the interior of the mill, causing a vacuum. This draws air from the bubbles in the batch, thus removing them. As a result it helps in easier and quicker grinding [10]. 6. 11 Discharge procedure Built-in discharge valves are generally located in the mill directly opposite the manhole opening. When the mill is spotted with the valve on the bottom to discharge, the manhole opening will be at the top. After the finished material is unloaded the discharge valve is closed, the manhole cover is removed, and a new batch of material may be dumped into the cylinder without having to turn the mill [10]. 6. 12 Cleaning of mill Good cleaning procedure is one of the most important factors in avoiding batch contamination. Where cleaning is necessary, the established procedure is to run the mill with a solvent or other liquid so that any of the products remaining around the media or sidewalls of the mill may be picked up and subsequently discharged. A good method of cleaning is to dump a small quantity of solvent into the mill, run it for 15 to 30 revolutions and dump it immediately. If necessary, the cycle can be repeated two or three times. In this way thorough cleaning is accomplished and batch contamination is avoided. The mill should not be run during cleaning for longer period of time. When no protective film is around the grinding media they will wear down very quickly. During a long cleaning run, a considerable amount of contamination is picked upon the surface of the grinding media. When the cleaning material is dumped out, a lot of this contamination remains in the mills. When a new batch of material is loaded, this dirt is absorbed and will come up in the finished product. At the same time the grinding media wear away, needing more frequent replenishing or dumping and sorting and excessive wear can also occur on the lining. Therefore, when cleaning, running time should definitely be kept to a minimum [10]. 6. 13 Maintenance of mill A well-made ball or pebble Mill will give many years of service with a minimum of maintenance costs and trouble. However, as with any equipment having moving parts, periodic maintenance checks are required for smooth performance and for low operating costs. These checkups take very little time or effort and are suggested to prevent any trouble from developing. Some of these checks include: 1. Material should not be allowed to accumulate on the outside of the cylinder. This adds to the weight and throws mill off balance. 2. Threads on the tightening bolts of the cover should be kept clean and occasionally oiled. 3. Lubricants recommended by the manufacturer should be strictly adhered to. 4. Lubricating periods are best determined by the operator and are generally controlled by existing conditions. 5. The level of the grinding media should be frequently checked. If it falls below the correct operating level, the required grinding media should be added. At longer intervals the charge should be dumped and inspected. All grinding media, which are excessively worn or damaged, should be removed and replaced with new media. 6. Even though a Mill may be perfectly aligned when new, occasionally it will settle after being in operation a while, due to the floor sag or settling of foundations. For this reason the alignment should be checked occasionally. 7. The foundation bolts should be examined periodically to see that they are secure [10]. 6. 14 Mill efficiency The controlling factors that govern the grinding efficiency of cylindrical mills are as follows [7]: 1. Speed of mill affects capacity, also liner and ball wear up to 65–75 percent of critical speed. 2. Ball charge equal to 35–50 percent of the mill volume gives the maximum capacity. 3. Minimum-size balls capable of grinding the feed give maximum efficiency. 4. Bar-type lifters are essential for smooth operation. 5. Higher circulating loads tend to increase production and decrease the amount of unwanted fine material. 6. Ratio of solids to liquids in the mill must be considered on the basis of slurry characteristics. 6. 15 Cares during mill operation The various cares to be taken during mill operation are [10]: 1. There should be enough material in the batch to cover the grinding media. 2. Grinding time is to be watched carefully to avoid excessive grinding. 3. Excessive buildup of heat should be avoided. In paint grinding, this may lower the operating viscosity beyond the critical point. A reduction in mill speed may help to avoid overheating, but it is more desirable to circulate a cooling medium around the cylinder. If the mill is not jacketed, a water spray can be used. 4. The smallest possible grinding media should be used. This reduces the danger of overheating. They also provide faster and better results. 5. When using extenders, their abrasive nature may cause excessive wear. To avoid this, extenders are held out until the grinding is almost complete and then they are added for the final operation. CHAPTER 7- FACTORS AFFECTING EFFICIENCY OF MILL 7. 1 Factors affecting the efficiency of the mill The various factors affecting the efficiency of the mill are as follows [7]: 1. Speed of Rotation 2. Relative volume of grinding medium and batch. 3. Size and density of grinding medium. 4. Consistency of batch. 7. 2 Speed of rotation There is a specific operating speed for most efficient grinding. At a certain point, controlled by the mill speed, the load nearest the wall of the cylinder breaks free and forms a cascading, sliding stream containing several layers of balls. The top layers in the stream travel at a faster speed than the lower layers thus causing a grinding action between them. There is also some action caused by the gyration of individual balls or pebbles. A pebble mill of the same size as that of ball mill usually runs at a slightly faster speed. This is due to the smaller inside diameter of the pebble mill with its lining, which is lacking in the ball mill. There is a point where the charge, as it is carried upward, breaks away from the periphery of the mill. This is called the â€Å"break point† or â€Å"angle of break† as it is measured in degrees. It is measured up the periphery of the mill from the horizontal. Usually the angle of break ranges from 50 to 60 degrees from the horizontal with the lower range recommended for wet grinding operations like paint manufacture and the higher break point (which provides a more severe grinding action) for dry materials. Angle of break should be lower for larger mills as compared to smaller mills because of severe grinding action in the mill. While in the old days operating speeds were determined by trial and error, now a days correlations are used to determine the critical speed, which is the speed at which the grinding media, without material, begin to centrifuge. The speed of rotation ranges from 50-60% of critical speed. According to Fischer [7] S=K/(D) ? Equation- 8 Where S is critical speed, K is constant and D is the diameter of the mill in ft. According to Coghill and De Vaney [7] S=54. 18/(R) ? Equation- 9 Where S is critical speed and R is the radius of the mill in ft. The smaller the mill the faster in RPM it has to run to attain critical speed. For example, 4. 5† diameter mill has a critical speed of 125 RPM, and 90† diameter ball mill has 28 RPM [7][9]. 7. 3 Relative volume of grinding medium and batch The volume of grinding medium and the volume of the paste in a mill affect the grinding time. For fastest grinding a pebble mill should contain 50-55% by volume of pebbles and a ball mill 45-50% of steel balls and in each case the paste should be sufficient to cover the grinding media slightly. Ball mills can contain as low as 33. 3% by volume of steel balls. This reduces the cost of balls and permits a larger loading space in the mill. However the grinding time is longer than with a 50% charge of balls. The grinding efficiency of the one -half charge is considerably greater than for the one-third, hence power consumption per gallon output will be less. Apart from this, the mills containing a low ball or pebble charge are harder to clean than when they are half full because paste tends to adhere to the ends of the mill and is difficult to remove when the charge is low. When the mill is half filled the grinding medium is continuously cleaning this area. The volume of voids between the spherical grinding media does not change with the size of the media. When a mill is charged with pebbles to 50% of its volume the voids among the pebbles are about 20% of the total volume of the mill. The minimum charge of paste is 25% of mill volume, which would give the fastest dispersion to the required fineness. The void volume between the grinding media, with a one-third charge of grinding media is 13 ? %. Fastest grinding occurs where there is just sufficient material in a batch to fill all voids and slightly cover the grinding media. This gives highest ratio of medium to paste. This equals approximately 25% of the total volume with a half ball charge and 18% with a one -third ball charge. The material should never be allowed to drop below the surface of the grinding media because when this happens excessive wear occurs to the mill and grinding media and contaminates the material itself. The largest size batches should not exceed 60% of total mill volume. Usually the minimum load of paste is 40-45% of mill volume and it can increase up to 60% but the grinding time also gets increased considerably. A 40% load requires twice the grinding time of the minimum 25% and the 60% load requires four times as long. It is not always necessary that the shortest grinding time is the most desirable. The mill can operate overnight without any attention therefore the loading can be increased to correspond to the overnight period and a larger yield of paste will be obtained. The size of load can be adjusted to conform to the specific working hours or the production schedules but in no case the load should be below the level of grinding medium, as it would result in excessive wear of the medium [7] [9]. 7. 4 Size and density of grinding medium The most common cause for faulty operation in a ball mill is regarding the size of grinding media. Usually smallest feasible grinding media are used. The optimum size of media should not change with mill size. If the laboratory pebbles or small balls successfully grind a sample batch in a lab ill, the same size grinding media can do the best job in a production mill irrespective of the size of the mill. The criteria is that the size and density of grinding media should be great enough to prevent them from floating in the material and to obtain the maximum amount of grinding surfaces. For steel balls the optimum size of balls recommended are ? † and 5/8†. However, balls of size as small as ? † in p roduction mills can be used and they are found to be extremely advantageous when exceptionally fine grinds are required. Figure 9 shows ? † and ? † sized steel balls. Porcelain balls range from 1-1. 5 in.. The heavy balls exert more force between them than light weight balls. However as the size of ball increases, to give it more weight, the surface area per weight decreases. To overcome this situation grinding medium of maximum possible density should be used, hence steel balls are preferred over pebbles in most of the cases. Balls of mixed size can provide greater area of contact between the balls. However there are chances of increased wear and more uneven wear of the balls with the possibility of large pebbles cracking or chipping the smaller ones. The advantages of small size grinding media are as follows: 1. They provide many more grinding contacts per revolution than larger media. This results in much quicker grinding action. One-inch balls have approximately 38 contacts per pound whereas 5/8 in. balls have 144. 2. They provide smaller voids, limiting the size of particles or agglomerates, which can exist there. 3. They do not create excessive energy, which cannot be utilized. Oversized grinding media frequently develop more grinding energy than is needed for the job. This excess builds up heat and wears down the media and the lining, introducing contamination in the batch. The disadvantages of small size grinding media are as follows: 1. Smaller balls tend to float or rise in the paste as the mill rotates. This can be overcome by lowering the pigment concentration to reduce the paste viscosity. However a stage reaches where reduced the grinding time is overbalanced by the smaller quantity of pigment ground. 2. Smaller balls or pebbles make a mill harder to discharge because of smaller channels in the mass through which the paste can flow, hence increased surface tension in the smaller voids. However, the reduced grinding time by using smaller media offsets this disadvantage. Slight air pressure can be used to assist in more rapid discharge. 3. Balls of too small a size will not be held back by the screen or grate in the discharge opening of the mill. These can cause serious trouble if they lodge in valves or in the pumping mechanism. 4. Small pebbles because of relative small size are less effective in breaking up large agglomerates of paste or pigment and may tend to promote formation of pigment balls in a mill. The attempts to increase the area of contact between the grinding media have produced tubular or rod shaped porcelain media. They have outside diameters of 13/16 in. nd 1 ? in. and lengths of the same dimensions. Porcelain balls of higher than normal density are also used. High density balls are used when the material is hard to grind or when the paste is of high viscosity [7] [9]. Figure 9: Steel Balls of ? † and ? † [5] 7. 5 Consistency of batch The consistency should be such so as to permit the particular size and density of grin ding media to move through the paste smoothly. The correct paste consistency is difficult to determine because it depends on the ball size, diameter of the mill, speed of the mill and density of the paste. If the consistency is too thick the entire charge moves as a mass and there will be no individual movement of balls and no grinding action takes place. If the paste is too thin there will be excessive wear on balls and mill lining, resulting in discoloration of the batch by abraded material, contamination and heat build-up. If the low viscosities cannot be avoided then small grinding media should be used. The range of the viscosities of the paste, handled by the various grinding media is shown in Table 1: Grinding Media |Size |Viscosity of paste (cp) | |Flint Pebbles |1 ? † |600-1100 | |Porcelain Balls |1- ? † |600-1100 | |High Density Balls |- |1100-2100 | |Steel Balls |? ? † |1100-2400 | Table 1: Viscosity of paste handled according to grinding media and size Small size balls are used for low viscosity paste while large size balls are used for high viscosity pastes. Consistency changes with difference in ratio of pigment to vehicle and with variation in solid con tent of the vehicle. To develop maximum shear the paste should be a viscous fluid however ball mill operation does not permit high consistency. Therefore the vehicles of relatively low solid content are used with high ratio of pigment to vehicle. The sound of the mill in operation is used to determine whether the consistency is correct or not. An experienced operator is able to tell if the sound volume is too high or too low for best grinding conditions. Though a noise meter can be also used but usually it is used in grinding ore or cement and not in paint industry. The consistency is affected by temperature hence it is important to know the operating temperature and it has to be maintained uniformly from batch to batch. Many mills like steel ball mills are jacketed for water cooling and temperature control [7] [9]. CHAPTER 8- TECHNOLOGICAL ASPECTS 8. 1 Technological Aspects The various technological aspects, which have to be taken care of during ball mill operation process, are: 1. When unloading materials that do not flow well some of the vehicle is held out until most of the batch has been removed from the mill. This vehicle is then added to the mill to help in removing as much of the batch as possible [7]. 2. Small size mills are used to produce small batches of paints [7]. . Ball formation in a mill is a major problem. In this situation a mass of pigment, balls or pebbles and some vehicle form a large round ball that will roll in the mill for hours and would not be broken. It is caused due to too high a paste level, too low a pebble level and too thin a paste. Increasing the consistency of a too thin paste will eliminate the ball formation because the more viscous paste tends to pull the round mass down below the surface of the grinding medium where all the dispersing action takes place [7]. 4. One of the most successful techniques employed in the dispersion of pigment in vehicle and solvent is known as low solids grinding [9]. The advantages of this technique are: a. Dispersion is accomplished quickly. b. A greater pigment quantity can be dispersed in a mill batch. 5. There are a few pigments on which it is desirable to avoid direct impact and attrition and dispersion of pigment relies mostly on shear, such as toluidine red. Excessive grinding through impact can destroy the pigment structure thereby reducing its hiding power. To avoid excessive grinding by impact the consistency should be heavier than for normal operation and the size batch should be sufficient to induce spreading of the grinding media in order to prevent direct contact and merely induce a shearing action [9]. 6. Step loading is more advantageous than tightly packing a bulky pigment to try and get it all in the mill in one loading as excessive packing can cause reaggregation of pigment particles [9]. 7. Periodic venting of the Mill relieves internal pressures and also helps in grinding [9]. 8. The use of wetting agents has greatly increased the capacity of ball mills and pebble mills without altering the viscosity during the grind. The capacity of the mill can increase from 50% (prior to the addition of wetting agent) upto 85% of solid content by using wetting agents. The wetting agents help in reducing the surface tensions of the aggregated particles, therefore grinding operation can occur in faster time and the finished product has greater stability [9]. 9. It is important to ensure that the batch size is consistent with the allowable running time. For example: if a 25% batch takes 9 hours, this would be too long for an 8-hour shift. In that case the batch size is increased and the mill is run to the next working day. Now if a 40% batch takes 9 hours, then a slight cutback can make it possible to turn out a batch within an 8-hour working day. Hence it is better to do a little experimenting with the batch size and to try to develop a system that will work out best as per the grinding conditions. However the grinding media must be covered with paste [9]. There are occasions where additional thinning of the batch after grinding may be done to increase the yield of the Mill. For example: in case of a pebble mill of volume of 450 gallons, a minimum material charge of 25% for this Mill would be 112 gallons and the maximum charge of 60% would be 270 gallons. After grinding, if the mill were loaded to the extreme top with thinner, the yield produced would be 315 gallons or 70% of the total volume of the mill [9]. 8. 2 Technological upgradation An example of technological upgradation is the use of adjustable timers in ball mills in liquid paint processing in Asian Paints Ltd. , Kasna Plant (UP). In Kasna Plant the ball mills in liquid paint processing used to run idly after the completion of grinding time in absence of any control switchgear. Hence adjustable timers were used. Table 2(a) shows the motor capacity, power consumption and running cost before the installation of the timers, while Table 2(b) gives the motor capacity, power consumption and running cost details after the installation of the timers. It has been observed that by the use of timers an annual saving of 0. 46 lacs has been achieved. [11] |Motor Capacity |55. kW | |Power consumption |3. 64 lacs kWh/annum | |Running Cost |15. 30 lacs/annum | Table 2(a): Kasna Plant details before installation |Motor Capacity |55. 2 kW | |Power Consumption |3. 3 lacs kWh/annum | |Running Cost |14. 83 lacs/annum | Table 2(b): Kasna Plant details after installation CHAPTER 9- CONCLUSIONS The followings conclusions can be made out regarding the use of ball mill in paint industry: 1. Paint manufacture involves dispersio n of pigment into binder and solvent components. 2. Steel ball mills and pebble mills are used for this purpose 3. Ball or pebble mills are used to make pigments uniform in the finished product. 4. They are used for grinding inexpensive coarse extender pigments in the batch to give more hiding power to the paint. 5. They are used in case of agglomerated pigments resulting from storage and handling. 6. Speed of rotation, volume of grinding medium and that of batch, size and density of grinding medium and consistency of the batch affect the efficiency of ball and pebble mills. CHAPTER 10- REFERENCES 1. Paint industry information, facts and figures by National Paint Coatings Association, Washington, US, www. aint. org 2. Paint from wikipedia, www. wikipedia. org 3. Gopala Rao. M and Sittig. Marshall: â€Å"DRYDEN’S OUTLINES OF CHEMICAL TECHNOLOGY†, Affiliated Eat West Press Pvt. Ltd. , 3rd Edition 2004 Reprint, pp 307-312. 4. Chemical fact sheet on paints by Orica Limited. Copyriht 1992-98. ACN 004 145 868. 5. Grinding from wikipedia, www. wikipedia. org 6. McCabe W. L, Smith J. C. , Harriott Peter: â€Å"UNIT OPERATIONS OF CHEMICAL ENGINEERING†, McGraw Hill Book Company, 6th Edition, International Edition 2001,pp 965-977. 7. Biblac V. C. , Edgar W. S. : â€Å"PAINTS WARNISH PRODUCTION MANUAL†, 1991, John Wiley and Sons, NY, pp 40-46, 132-137, 996-1004. 8. Presentation given by P. Poornima, R. Sreenivasan, Ankit Bhatnagar in IIT-Chennai on ball mill operation. 9. Handbook of grinding by Paul O Abbe, A division of Aaoron Engineered Process Equipment, Inc. , 1994 10. Ball mill handbook by Paul O Abbe, A division of Aaoron Engineered Process Equipment, Inc. , 1994. , www. pauloabee. com. 11. Asian Paints Ltd. , Kasna Plant, UP, Unit Profile, www. asianpaints. com

Mudarse Conjugation in Spanish, Translation, and Examples

Mudarse Conjugation in Spanish, Translation, and Examples The reflexive verb mudarse means to move in the sense of changing ones residence, such as moving to a new house or apartment. For all other meanings of the verb to move, Spanish uses the verb mover. The non-reflexive verb mudar means to change, but it is not used very frequently. Mudarse is a much more commonly used verb. Therefore, this article contains mudarse conjugations in its reflexive form in the indicative mood (present, past, conditional, and future), the subjunctive mood (present and past), the imperative mood, and other verb forms. Mudarse Present Indicative The verb mudar is a regular -ar verb, so it follows the regular conjugation pattern. To conjugate mudarse, the reflexive pronoun should be included before each conjugated form. Yo me mudo I move Yo me mudo al dormitorio con mi compaà ±era. Tà º te mudas You move Tà º te mudas a otra ciudad por tu trabajo. Usted/à ©l/ella se muda You/he/she moves Ella se muda a un apartamento ms grande. Nosotros nos mudamos We move Nosotros nos mudamos a un condominio. Vosotros os mudis You move Vosotros os mudis a la casa nueva despuà ©s de la boda. Ustedes/ellos/ellas se mudan You/they move Ellos se mudan a otro paà ­s para asistir a la universidad. Mudarse Preterite Indicative The preterite tense is used to describe completed actions in the past. Yo me mudà © I moved Yo me mudà © al dormitorio con mi compaà ±era. Tà º te mudaste You moved Tà º te mudaste a otra ciudad por tu trabajo. Usted/à ©l/ella se mudà ³ You/he/she moved Ella se mudà ³ a un apartamento ms grande. Nosotros nos mudamos We moved Nosotros nos mudamos a un condominio. Vosotros os mudasteis You moved Vosotros os mudasteis a la casa nueva despuà ©s de la boda. Ustedes/ellos/ellas se mudaron You/they moved Ellos se mudaron a otro paà ­s para asistir a la universidad. Mudarse Imperfect Indicative The imperfect tense is used to describe ongoing or repeated actions in the past. It can be translated as was moving or used to move. Yo me mudaba I used to move Yo me mudaba al dormitorio con mi compaà ±era. Tà º te mudabas You used to move Tà º te mudabas a otra ciudad por tu trabajo. Usted/à ©l/ella se mudaba You/he/she used to move Ella se mudaba a un apartamento ms grande. Nosotros nos mudbamos We used to move Nosotros nos mudbamos a un condominio. Vosotros os mudabais You used to move Vosotros os mudabaisa la casa nueva despuà ©s de la boda. Ustedes/ellos/ellas se mudaban You/they used to move Ellos se mudaban a otro paà ­s para asistir a la universidad. Mudarse Future Indicative The future tense is conjugated with the infinitive form mudar and the future tense endings (à ©, s, , emos, à ©is, n). Yo me mudarà © I will move Yo me mudarà ©al dormitorio con mi compaà ±era. Tà º te mudars You will move Tà º te mudars a otra ciudad por tu trabajo. Usted/à ©l/ella se mudar You/he/she will move Ella se mudar a un apartamento ms grande. Nosotros nos mudaremos We will move Nosotros nos mudaremosa un condominio. Vosotros os mudarà ©is You will move Vosotros os mudarà ©isa la casa nueva despuà ©s de la boda. Ustedes/ellos/ellas se mudarn You/they will move Ellos se mudarn a otro paà ­s para asistir a la universidad. Mudarse Periphrastic  Future Indicative   When conjugating the periphrastic future, remember to place the reflexive pronoun before the conjugated verb ir (to go). Yo me voy a mudar I am going to move Yo me voya mudar al dormitorio con mi compaà ±era. Tà º te vasa mudar You aregoing to move Tà º te vasa mudar a otra ciudad por tu trabajo. Usted/à ©l/ella se vaa mudar You/he/she isgoing to move Ella se vaa mudar a un apartamento ms grande. Nosotros nos vamosa mudar We aregoing to move Nosotros nos vamosa mudar a un condominio. Vosotros os vaisa mudar You aregoing to move Vosotros os vaisa mudar a la casa nueva despuà ©s de la boda. Ustedes/ellos/ellas se vana mudar You/they aregoing to move Ellos se vana mudar a otro paà ­s para asistir a la universidad. Mudarse Present Progressive/Gerund Form The gerund or present participle can be used as an adverb or to form progressive tenses like the present progressive. Progressive tenses often use the auxiliary verb estar. There are two options for placing the reflexive pronoun in the present progressive tense. It can be placed before the conjugated verb estar, or attached to the end of the present participle. Present Progressive ofMudarse se est mudando / est mudndose Is moving Ella se est mudando a un apartamento ms grande. Mudarse Past Participle The past participle is often used in perfect tenses like the present perfect. The present perfect uses the auxiliary verb haber. In this case, the reflexive pronoun must be placed before the conjugated verb haber. Present Perfect of Mudarse se ha mudado Has moved Ella se ha mudado a un apartamento ms grande. Mudarse Conditional Indicative The conditional tense can used to talk about possibilities. It is conjugated using the infinitive form and the conditional endings. Yo me mudarà ­a I would move Yo me mudarà ­aal dormitorio con mi compaà ±era si hubiera espacio. Tà º te mudarà ­as You would move Tà º te mudarà ­as a otra ciudad por tu trabajo si te dieran la promocià ³n. Usted/à ©l/ella se mudarà ­a You/he/she would move Ella se mudarà ­a a un apartamento ms grande si lo pudiera pagar. Nosotros nos mudarà ­amos We would move Nosotros nos mudarà ­amosa un condominio, pero no tenemos suficiente dinero. Vosotros os mudarà ­ais You would move Vosotros os mudarà ­aisa la casa nueva despuà ©s de la boda, pero no estar lista. Ustedes/ellos/ellas se mudarà ­an You/they would move Ellos se mudarà ­an a otro paà ­s para asistir a la universidad si les dieran la beca. Mudarse Present Subjunctive The present subjunctive of -ar verbs is formed with the endings e, es, e, emos, à ©is, en. Que yo me mude That I move La directora pide que yo memudeal dormitorio con mi compaà ±era. Que tà º te mudes That you move El jefe espera que tà º temudes a otra ciudad por tu trabajo. Que usted/à ©l/ella semude That you/he/she move La familia quiere que ella semude a un apartamento ms grande. Que nosotros nos mudemos That we move Carlos quiere que nosotros nos mudemos a un condominio. Que vosotros os mudà ©is That you move El abuelo recomienda que vosotros os mudà ©is a la casa nueva despuà ©s de la boda. Que ustedes/ellos/ellas semuden That you/they move La profesora sugiere que ellos semuden a otro paà ­s para asistir a la universidad. Mudarse Imperfect Subjunctive The imperfect subjunctive can be conjugated in two different ways. Option 1 Que yo me mudara That I moved La directora pedà ­a que yo memudaraal dormitorio con mi compaà ±era. Que tà º te mudaras That you moved El jefe esperaba que tà º temudaras a otra ciudad por tu trabajo. Que usted/à ©l/ella semudara That you/he/she moved La familia querà ­a que ella semudara a un apartamento ms grande. Que nosotros nos mudramos That we moved Carlos querà ­a que nosotros nos mudramosa un condominio. Que vosotros os mudarais That you moved El abuelo recomendaba que vosotros os mudarais a la casa nueva despuà ©s de la boda. Que ustedes/ellos/ellas semudaran That you/they moved La profesora sugerà ­a que ellos semudaran a otro paà ­s para asistir a la universidad. Option 2 Que yo me mudase That I moved La directora pedà ­a que yo memudase al dormitorio con mi compaà ±era. Que tà º te mudases That you moved El jefe esperaba que tà º temudases a otra ciudad por tu trabajo. Que usted/à ©l/ella semudase That you/he/she moved La familia querà ­a que ella semudase a un apartamento ms grande. Que nosotros nos mudsemos That we moved Carlos querà ­a que nosotros nos mudsemosa un condominio. Que vosotros os mudaseis That you moved El abuelo recomendaba que vosotros os mudaseis a la casa nueva despuà ©s de la boda. Que ustedes/ellos/ellas semudasen That you/they moved La profesora sugerà ­a que ellos semudasen a otro paà ­s para asistir a la universidad. Mudarse Imperative To give orders or commands you need the imperative mood. Notice that in positive commands, the reflexive pronoun is placed after the verb, while in negative commands, the reflexive pronoun is placed before the verb. Positive Commands Tà º mà ºdate Move!  ¡Mà ºdate a otra ciudad por tu trabajo! Usted mà ºdese Move!  ¡Mà ºdese a un apartamento ms grande! Nosotros mudà ©monos Let's move!  ¡Mudà ©monos a un condominio! Vosotros mudaos Move!  ¡Mudaos a la casa nueva despuà ©s de la boda! Ustedes mà ºdense Move!  ¡Mà ºdense a otro paà ­s para asistir a la universidad! Negative Commands Tà º no te mudes Don't move!  ¡No te mudes a otra ciudad por tu trabajo! Usted no se mude Don't move!  ¡No se mude a un apartamento ms grande! Nosotros no nos mudemos Let's not move!  ¡No nos mudemos a un condominio! Vosotros no os mudis Don't move!  ¡No os mudis a la casa nueva despuà ©s de la boda! Ustedes no se muden Don't move!  ¡No se muden a otro paà ­s para asistir a la universidad!

Experimental economics summary paper Essay Example | Topics and Well Written Essays - 500 words - 15

Experimental economics summary paper - Essay Example information regarding quality and to ensure quality control is through the use of a third party that certifies and endorses products to comply with certain standards. A total of 21 buying sessions with 20 trading periods per session were conducted having 5 sellers and 6 buyers per period. The sellers could sell two super or two regular grade products per session. They had to pre-commit to quality in secret prior to any selling taking place. The fact that regular costs less to produce is a universal fact and all subjects were aware of it. They did not however know the actual difference. Offers were posted up on a whiteboard and at the end of each period, the grades of goods sold revealed. The reputation-only phase of the experiment kept the identities of sellers and hence their sales records revealed. The cheap-talk signaling phase gave sellers the option of either displaying a grade to buyers, or displaying no grade and just the pricing information and numbers up for sale. The certification part entailed ‘paying’ a fixed amount by the seller to certify their goods. The findings hence are in the categories of reputation, perception cr eated by â€Å"cheap-talk† and third-party certification and endorsement. It was discovered that reputation alone may not be enough to satisfy buyers of the quality they were paying for. The number of goods sold increased when compared to the baseline model where no information regarding quality was available. In the second part of the study, sellers were asked to label their goods with vague environmental quality claims. These also were discovered to be not enough in increasing efficiency or the number of high-quality units. This sort of cheap-talk signaling was found to be effective only when buyers were experienced. In the final part of the study dealing with certification, it was found that verifiable claims where a third party was introduced to monitor quality can help consumers find the information they need before buying.

M4A1 PART A Essay Example | Topics and Well Written Essays - 500 words

M4A1 PART A - Essay Example Schein (2010) has rightly affirmed that a common pattern of basic assumptions should be shared among the group members so that they can effectively solve the problems; when everyone has the same set of values and norms, then internal integration and external adaptation becomes easier and it has worked positively for the overall organization. The new members of an organization should be taught the same way of perceiving, thinking and feeling about the problems so that the conflicts are avoided. Hence, it is stated by Schein that an effective manager has to ensure that he/she advances in the organizational studies by observing the real behavior of the workforce which are labeled as values, assumptions and artifacts (Bohlander & Snell, 2007). According to Jung et al. (2009), Schein categorized the signals of cultures and subcultures in three stages; the first stage is known as ‘artifacts’ which are the attributes that are evident as they can be heard, felt and seen such as dressing style, communication medium, tone of voice, stories and etc. Artifacts are in the form of company’s mission, slogans, written communication mediums and slogans; all of them are easy for observation but challenging for deciphering (Cameron & Quinn, 2011). The second stage is known as ‘values’ which is slightly complicated in nature but are observable to a certain extent. For instance, during the interview process, a manager can make some judgment about the candidate’s values by observing him/her. Finally, in the third stage which is known as ‘basic assumptions’ are the most difficult ones to be observed as they are deeply embedded in the person’s behavior. They behavior becomes evident when the person starts working in the organization. Hence, all of these stages combine to define the attention aspect for the HR manager because it

Describe an incident or situation that has occured during your student Essay

Describe an incident or situation that has occured during your student practice and discuss a related professional issue - Essay Example So I asked her, in a discreet manner what was wrong. She explained that she was embarrassed so I wheeled her back into her room and fed her in there. If this lady had been asked where she would like to eat, her choice would have been to stay in her room and eat where she felt her dignity would have been maintained. If I had not of spoken to her she would rather chose not to eat, or other patients, having no intentions, will invade her privacy and see her feed. As a nurse, it is vital that a patient’s dignity is respected at all times. By preserving dignity, a nurse can also preserve the integrity of the patient. In this scenario, it is clear that a violation in privacy and person’s dignity occurred through humiliation, embarrassment, not respecting patient’s autonomy regarding preferred feeding, and depersonalization (Watson, 2008, p. 133). Healthcare delivery in the contemporary era focuses on being patient centered, risk managed, quality assured and cost effective (Mallik, 2009, p. 14). Accountability has grown increase importance in delivering quality health care by expanding the responsibility of caring and accountability to a health team instead of individuals. Accountability is defined as being accountable of your actions by explaining and justifying why and what you did. It involves assessment of the best interests for patients, knowledge and judgment in decision-making, and explanation to defend course of action (Walsh, p. 89). Since accountability promotes the best interests of the patients, it is essential that nurses respect privacy, which is one basic right of human dignity. Privacy is a major factor considered in caring. Among of the privacy concerns of patients are depersonalization and intimate questions, hospital procedures, and treatments (Watson, 2008, p. 133). Privacy was linked to preservation of human dignity and maintenance of integrity and hence is considered as an essential health need

The Vital Capacity Test In Football

The Vital Capacity Test In Football Football has become a sport that interest by all population in this world. To play or become a good football player, the person must master many skills and have a healthy physical and mental. Football players also must combine speed, strength, agility, power, and endurance as basic qualities before the individual skills inherent to the playing of soccer can be utilized and depend on the position such as defense, strikers, midfielder and goal keeper. The understanding of the physical and the mental demands of the sport will enable a more scientific approach to the training of soccer players by (Bell and Rhodes 1975; Caru et. al. 1970; Fardy 1969). Football is one of the sports that need high intensity of workload or physical activity, for example the combination of walk and repeated sprints need sufficient recovery between activity. Stated by (Nicks et. al. 2006) and Romer et.al. So the player must have strong muscles, high muscular endurance, have strong core and have high level of aerobic capacity because the football game are played for 90 minutes. So the training must contain high aerobic training to improve cardiovascular and pulmonary functions so the athlete can cope with the sport. Physiological assessment of athletes can provide an opportunity to examine or test the adaptation to specific types of exercises and training. These adaptations can be valuable to the clinician, coaches and athletes themselves. For example, lab test that can be proceed to examine the adaptation to specific types of exercises and training. To test the adaptation to the lung we can use pulmonary functions test to examine the effectiveness of lung muscles functioning, to check the vital capacity and to estimate the lung volumes. The function of the lung is to deliver O2 to gas exchanged surface and exhaust CO2 to atmosphere. To achieve this with brain functioning normally, breath begins with contraction of inspiratory muscle enlarging the thorax, lowering intrathoracic and pleural pressures, enlarging the alveoli and airways, expanding the alveolar gas so reducing its pressure below atmospheric. Air at atmospheric pressure must flow into the thorax where it is conducted to, and diffuses, out into the alveoli. The carriage of air through the airways depends on the patency of the tube as well as on the consistency of the lung and the power of the respiratory muscles. At any one moment approximately 100ml of desaturated blood, with a strong affinity for O2, is spread over an area of 70 square meters( area of pulmonary capillary bed ) separated from air by a membrane 0.2 micron thick. Oxygen from alveolar air diffuses rapidly across the alveolar capillary membrane and is finally chemically combined with hemoglob in molecules within the circulating red blood cells (RBC), CO2 diffuses into opposite direction and is eliminated in expired gas. The Vital capacity test is one of the oldest and most common respiratory tests. The measurement of vital capacity (VC) simply requires that an individual blow as large a breath of air as possible into a spirometer. Thus, the person expels three of the four components of the total lung volume when performing the vital test. There are inspiratory reserve volume (IRV), tidal volume (TV) and expiratory reserve volume (ERV). It provides an indirect indication of the size of the lung, although it is not a complete measure of the entire lung size because it does not account for residual volume. In general facts, vital capacity relate to three uncontrolled characteristics which are age, stature and gender. Lung function measurements also may be made for several reasons. They are useful in describing the lung for diagnostic purpose and subsequently in monitoring change. Accuracy and consistency are therefore very important, and a convention exists for the procedure of measurement and expression of result. In general, a measurement will only be accepted after multiple attempts have been scrutinized and expressed under standard conditions. These are usually body temperature and atmospheric pressure. To guarantee accuracy, laboratory practice should include regular physical and biological calibration of the equipment. Standard for good laboratory conduct have been described greatly by British Thoracic Society or association of respiratory technologist and physiologist 1997. In health there are several factors which influence the magnitude of the lung function. These include height, sex, age, and to a lesser degree weight and ethnic origin (Cotes1979, Anthonisen1986). As a result, assessment of normalcy can only be compared with reference values. The better can be obtained from the study of larger numbers of normal people from the relevant population (European community for Coal and Steel 1983). Once obtained, results can be expressed as percentage predicted or, more correctly, by comparison with the 95% confidence interval for the valves. Problem statement. It is interesting to know whether there are any different of lung volumes and lung capacities base on the different position in the football team such as striker position and defenses position. In football team, the defenders position tasks are different with the striker position task, for example the defensive position, the job of the centre backs or  central defenders  is to stop opposing players, particularly the strikers, from getting the opportunity to score, and to clear the ball from their own penalty area. So usually the defense has big physical to stop the striker, but different with the striker position, usually the strikers position players have not too big physical, because these positions are for the fast person to score the goal. This study of pulmonary function of the Uitm football players base on position, have taken students group of both striker position and defense position of aged between 19-25 years and focused on essential parameters including, FVC and has used Spirometer. The spirometer device used to assess these parameters. This study mainly concentrates on lung parameters including Forced Vital Capacity (FVC) and how far it varies base on the position such as striker and defense. The FVC also use to assess the lung function of Uitm soccer players. Operational Terms 1.2.1 Exhalation is act or an instance of exhaling air. From journal sources Masaoka Y, Satoh H, Akai L, Homma I. (2010) 1.2.2 Inhalation is the drawing of air or other substances into the lung. From internet sources http://en.wikipedia.org/wiki 1.2.3 Total lung capacity are refers to the total amount of air in the lungs after taking the deepest breath possible. From internet sources http://en.wikipedia.org/wiki 1.2.4 Ventilation is a cyclic process of inspiration and expiration whereby optimal levels of Oxygen and cabondioxide are maintained in the alveoli and arterial blood. 1.2.5 Tidal Volume (VT) is defined as the amount of air that is inspired and expired during normal resting ventilation. 1.2.6 Forced Vital Capacity (FVC) is the maneuvers in which the maximum amount of air that can be exhaled following a inspiratory effort. 1.2.7 Maximum voluntary ventilation (MVV) can be defined as the maximum volume of air that can be breathed by a person in one minute. From internet sources http://www.answer.com/topic/maximum-breathing-technique Objectives In this study, there are some purposes or objective that can be seen. They are; To measure the level of fitness of Uitm football players by using force vital capacity y test. To determine whether there is a different in pulmonary functions base on position in football team such as defense and striker. 1.4 Hypothesis H °-There is no significant different on pulmonary functions in football position such as striker and defense H ª-There is significant different on pulmonary functions in football position such as striker and defense 1.5 Significant of the study The significant of this study is mainly to measure and compare the lung volumes and capacities among the Uitm football player base on their position. Does the football position such as striker position and defenses position have differences effects on the lung volumes and capacities? The study is important because it can help certain peoples such as coach, physiotherapy and athletes especially in any kinds of sports to improve pulmonary functions. In addition, this study also can increase knowledge of coach and athletes, and show them how important is to have efficient and strong lung to improves their performances for their sport. 1.6 Delimitation The first delimitation is the number of any kinds of research subjects, which consists thirty (n=30) age range from 19-25 years old will take part in this study. The subjects are selected in the Uitm football team and physically active and all the participants must be healthy. The subjects are divided into two groups of defense and striker. The others delimitation is the subject gender and age. The test will be conduct in Physiology Lab. Limitation In this study, the participants involved may have some experience in vital capacity test. The participants that will be selects in this study will be participating in the lab test by using spirometer. The participation is important in this study because it can affect the results and data if the participants do not cooperate and participate willingly. Besides that, the time constrains also can be one of the factors because the participants have their own schedules and will clash with the test schedules and can not attend the test. In addition, money can be a problem because, there is no sponsored in this study. The daily activities of the participants will not be controlled. Assumption In this study, it can be assumed that all the participants can do and completed the vital capacity test. Thus, I also believe and make sure that all the participants will understand and follow all the instruction given by the technician. The researchers also predict that all the participants are physically active and healthy. The researcher assumed that the test in this study instrumentation was appropriate for the target population. I also predict that all the participants fully understood the types of test and method and how to perform it correctly.

Human Resource Management Essay -- Business Resource Managing Essays

Human Resource Management Effective human resource management is undoubtedly critical to the success of virtually all firms. Thus its importance is huge in the study of business strategy; which is the system of the firm’s important choices that are critical to the firm’s survival and relative success (Boxall and Purcell 2003). Getting more specific, strategic human resource management as a field of study is concerned with the strategic choices associated with the use of labour in firms and with explaining why some firms manage them more effectively than others (Boxall and Purcell 2003). Traditionally there has been much debate in the field of strategic HRM over two main schools of thought; â€Å"best fit† (contingency theory), and â€Å"best practice† (universalism). The â€Å"best fit† school of thought argues that HR strategy will be more effective when it is appropriately integrated with its specific organizational and broader environmental context (Boxall and Purcell 2003). This proposes questions about which are the most critical contingencies in this context and how they are best connected. The ‘best practice’ school of thought argues that all firms will see performance improvements if only they identify and implement best practice. This perspective requires top management to commit themselves to key HR practices. Basically, the idea is that a particular bundle of HR practices has the potential to contribute improved employee attitudes and behaviours, lower levels of absenteeism and labour turnover, and higher levels of productivity, quality and customer service. This has the ultimate effect of generating higher levels of profitability (Boxall and Purcell 2003). Both of the aforementioned â€Å"best theory† approaches to strategic HRM place emphasis on critical choices associated with competitive strategy; such as which industry to enter and what competitive position to seek in it (Boxall and Purcell 2003). However, these models make some serious assumptions of the firms HRM. They assume that the firm already has a clever leadership team that makes the competitive strategy choices effectively. They also assume that human resource issues such as hiring and training a capable workforce are straightforward and basic. The resource-based view (RBV) of strategy, a modern school of thought in the field of strategic HRM, sees these issues as strategic rather than stra... ... over time, and their importance to sustained competitive advantage (Boxall and Purcell, 2003). Works Cited Boxall, Peter and Purcell, John. Strategy and Human Resource Management. Palgrave  Ã‚  Ã‚  Ã‚  Ã‚  Macmillan. 2003. Deephouse D. ‘To be different, or to be the same? It’s a question (and theory) of   Ã‚  Ã‚  Ã‚  Ã‚  strategic balance’ , Strategic Management Journal, Vol. 20, 1999. pp147-166 Mabey, Christopher and Salaman, Graeme and Storey, John. Human Resource   Ã‚  Ã‚  Ã‚  Ã‚  Management: A Strategic Introduction. Blackwell Business. 1998. Marchington, Mick and Wilkinson, Adrian. People Management and Development:   Ã‚  Ã‚  Ã‚  Ã‚  Human Resource Management at Work. CIPD Enterprises Ltd. 2002. Purcell, John. â€Å"Business Strategies and Human Resource Management: Uneasy   Ã‚  Ã‚  Ã‚  Ã‚  Bedfellows or Strategic Partners?† University of Bath. April 27, 2005   Ã‚  Ã‚  Ã‚  Ã‚  [http://www.bath.ac.uk/werc/pdf/business_strategies_and_HRM.pdf] Sisson, Kieth and Storey, John. The Realities of Human Resource Management:   Ã‚  Ã‚  Ã‚  Ã‚  Managing the Employment Relatoinship. Open University Press:   Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Buckingham.   Ã‚  Ã‚  Ã‚  Ã‚  2000. Schuler, Randall S. and Jackson, Susan E. Strategic Human Resource Management.   Ã‚  Ã‚  Ã‚  Ã‚  Blackwell Publishers Ltd. 1999.

An Investigation into using Artificial Intelligence in Education

Over the past decennary, educational establishments have progressively offered online, web-based classs. While there has been a great trade of research comparing the effectivity of online and traditional classs ( Young, 2006 ) , there has been less research on how to utilize instructional design schemes to increase pupil battle, pupil satisfaction, and accomplishment in online classs ( Gunter, 2007 ) . Research has shown that instructional immediateness can increase knowledge and pupil success ( LaRose & A ; Whitten, 2000 ) . Educators learning online have turned to assorted engineerings to better student-to-instructor interactions. Personal response systems, teleconferencing tools, and computer-supported collaborative acquisition ( CSCL ) environments have been used ( Soh, Khandaker, & A ; Jiang, 2008 ) . Educators have used confabs Sessionss to ease communicating, every bit good. However, pupils frequently are required to run into in a confab room or teleconferencing during preset times. While holding synchronal meetings does better student-to-instructor interaction, these systems are mostly inactive ( Soh et al, 2008 ) . Artificial intelligence is a engineering that can supply immediate responses to user inquiries and it can accommodate to single users demands. This paper will discourse what unreal intelligence is and how unreal intelligence has been used. It is hypothesized that the usage of unreal intelligence in online classs will increase pupil success and battle. Artificial intelligence can be defined as the scientific discipline and technology of making intelligent machines, computing machine plans in peculiar ( McCarthy, 2007 ) . There are multiple subdivisions of unreal intelligence or AI, as it will be referred to for the balance of this paper. Logical AI refers to what a plan knows about the universe in general and the facts of a peculiar state of affairs in which it must move. Goals are represented by mathematical logical linguistic communication and the AI Acts of the Apostless by infering which actions are appropriate for accomplishing its ends ( McCarthy ) . Search AI plans study big Numberss of possibilities. A cheat playing computing machine is an illustration of a hunt AI plan. There are pattern acknowledgment AI plans. These types of AI plans are programmed to compare what it sees with a form. There are AI plans that can be after or larn from experience ( McCarthy ) . These illustrations of assorted AI plan types are non thorough . AI plans have been designed for multiple educational intents. I-MINDS is an AI plan that has been created to assist teachers with schoolroom direction and to increase pupil coaction. The theoretical model of the I-MINDS intelligent computer-supported collaborative acquisition ( CSCL ) environment was based on three cardinal rules. In the first rule, the writers proposed constructing a CSCL system that was â€Å" antiphonal, flexible, distributed, and adaptative to single pupil behaviours † ( Khandaker et al. , 2008, p. 3 ) . In the 2nd rule, the writers desired to construct a CSCL â€Å" that is able to germinate over clip in footings of its pedagogical cognition, pupil and even group mold, and public presentation in determination support † ( Khandaker et al. , 2008, p. 3 ) . In the 3rd rule, the writers proposed constructing a CSCL system â€Å" is able to organize effectual pupil larning groups on its ain † ( Khandaker et al. , 2008, p. 3 ) . The writers studied the impact of I-MINDS on structured concerted acquisition. A two-semester survey was launched at the University of Nebraska during the Spring and Fall semesters of 2005. I-MINDS was deployed and evaluated in an introductory computing machine scientific discipline class. The survey utilized a control subdivision where a group of pupils did non utilize I-MINDS. The writers ‘ consequences show â€Å" that I-MINDS can back up concerted larning efficaciously in the topographic point of face-to-face coaction among pupils in hebdomadal research lab Sessionss † ( Khandaker et al. , 2008, p. 28 ) . The consequences besides show that modular extension to the system is supported. Finally, I-MINDS collected informations that provided critical information on pupil group activities. This showed that I-MINDS can be used efficaciously as a test-bed for educational research. AI plans can be developed to supply individualised and adaptative linguistic communication acquisition and vocabulary tutoring. In Personalization of Reading Passages Improves Vocabulary Acquisition by Heilman, Collins-Thompson, Callan, & A ; Eskenazi, the REAP tutoring system, which provides English as a Second Language vocabulary pattern, was examined. Harmonizing to the writers, â€Å" REAP can automatically personalise direction by supplying pattern readings about subjects that match involvements every bit good as domain-based, cognitive aims † ( Heilman, Collins-Thompson, Callan, & A ; Eskenazi, 2010 ) . The writers pointed out that most old research on motive in intelligent tutoring environments has focused on increasing extrinsic motive. The writers focused their survey on increasing personal involvement. The pupils in the survey were indiscriminately split into control and intervention groups. The control status coach selected texts to maximise domain-based ends. The t reatment-condition coach besides preferred texts that matched personal involvements. The consequences show positive effects of personalization. In add-on, the importance of negociating between motivational and domain-based ends was demonstrated ( Heilman et al. , 2010 ) . Gunter, G. ( 2007 ) . The effects of the impact of instructional. International Journal of Human and Social Sciences, 2 ( 3 ) , 195-201. Heilman, M. , Collins-Thompson, K. , Callan, J. , & A ; Eskenazi, M. ( 2010 ) . Personalization of reading transitions improves vocabulary. International Journal of Artificial Intelligence in Education, 20, 73-98. LaRose, R. , & A ; Whitten, P. ( 2000 ) . Re-thinking instructional immediateness for web classs: A societal cognitive geographic expedition. Communication Education, 49 ( 4 ) , 320-338. McCarthy, J. ( 2007, November ) . What is Artificial Intelligence? Retrieved February 14, 2011, from Basic Questions: hypertext transfer protocol: //www-formal.stanford.edu/jmc/whatisai/node1.html Soh, L. , Khandaker, N. , & A ; Jiang, H. ( 2008 ) . I-MINDS: a multiagent system for intelligent computer-supported collaborative acquisition and schoolroom direction. International Journal of Artificial Intelligence in Education, 18 ( 2 ) . Young, S. ( 2006 ) . Student positions of effectual online instruction in higher. The American Journal of Distance Education, 20 ( 2 ) .

To investigate a factor which will affect, the resistance of wire Essays

To investigate a factor which will affect, the resistance of wire Essays To investigate a factor which will affect, the resistance of wire Essay To investigate a factor which will affect, the resistance of wire Essay Aim: to investigate a factor which will affect, the resistance of wire.There are four different factors we could choose to vary:-1. Thickness/diameter of the wire2. Length of wire3. Material of wire4. temperature of wireWe decided to change the factor length because it allows us to get continuous data in a large range. It is also the easiest to vary. I decided against Diameter of wire because it is hard to compare to resistance (they cannot be plotted against one another because as resistance goes up the thickness goes down), I also decided not to vary the material the wire is made of because it would give us discrete data which is hard to analyse. Temperature is a very bad variable because it is so hard to control; the circuit will increase in temperature whatever I do, so I need to take that into account.RESISTANCEResistance is anything in the circuit which slows the flow down. We know that Length affects this because as length increases so does resistance. Ohms Law, Potential Difference (V) across a conductor is directly proportional to the current (I) flowing through it, providing the temperature is the same.R=V/I resistance= voltage/currentResistivity: p=RA/lResistivity=resistance X cross section of the wire / length of wirePRELIMINARY REULTSWe did a short preliminary experiment to see how the resistance affected the temperature of the wire, when we put one crocodile clip at 0mm and one at 100mm the wire got so hot it began to burn and give off smoke. From this preliminary experiment we decided not to take any measurements under 100mm because it could become unsafe.RANGE OF RESULTSWe have decided to take results at 100mm, 200mm, 300mm, 400mm, 500mm, 600mm, 700mm, 800mm and 900mm we shall take each measurement twice. This should give us a wide enough range of results to plot on Graphs we will also re-do any anomalous resultsPREDICTIONI predict that as the length increases so will the Resistance because Ohms law states that potential difference is directly proportional to current and the current will increase as the length of the wire increases because there will be more resistance on it (it will be more spread out, current is carried by electrons in metals)SAFE TESTTo make sure everything is safe whilst carrying out the experiment safety goggles must be worn and the wire must not be touched while current is flowing round it and shortly after because it will be hot.FAIR TESTTo make sure the investigation is fair, we will use the same equipment each time, monitor the temperature (if the wire start to give off smoke we will stop and give it time to cool down to reduce anomalies) and we will measure our wire using a micrometer to check the width before doing any equations.EQUIPEMENTPower pack, to power our experiment so current flows through the wire.Ammeter, to measure the current flowing round our circuit.Voltmeter, to measure the voltage of our circuit.1m Nicrome Wire, to test.Wire, to put, our circuit together with.Metre rule, to measure the lengths of wires.Crocodile clips, to hold wires in place.DIAGRAMMETHOD1. set up apparatus as above2. Put crocodile clips at 0mm and 900mm3. Turn power pack on4. record Current and Volts5. Turn off Power pack6. Repeat steps 1-47. Repeat steps 2-6 but with 800mm.700mm, 600mm,500mm,400mm,300mm,200mm and 100mmWe can clearly see my results are correct because the constant is constant. To make our results accurate we used the same equipment each time, kept an eye on the temperature(When the wire started to give off smoke we stopped and give it time to cool down to reduce anomalies), we used digital a digital ammeter and voltmeter to reduce human error and we measured our wire using a micrometer to check the width before doing any equations. The width was 26mgs which is : 0.45 mm.ANAYLSISWe can clearly se that our graph supports our prediction, As the length increases so does the resistance, this tells us that Length and resistance are directly proportional. We can now work out the resistivity of the different lengths of wire:100mmResistivity=0.785 x 0.45100Resistivity=0.00353200mmResistivity=1.49 x 0.45200Resistivity= 0.00335300mmResistivity=2.11 x 0.45300Resistivity= 0.00352400mmResistivity=1.34 x 0.45400Resistivity= 0.00151500mmResistivity= 1.055 x 0.45500Resistivity= 0.00095600mmResistivity= 0.88 x 0.45600Resistivity= 0.00066700mmResistivity=0.81 x 0.45700Resistivity= 0.00052800mmResistivity=0.71 x 0.45800Resistivity=0.00040900mmResistivity= 0.62 x 0.45900Resistivity= 0.00031EVALUATIONOnly one anomalous result was obvious whilst carrying out our investigation (at 700mm) so we went back and did it again. Unfortunately when looking at my graph it seems there were more anomalies, I have circled them in the table and on the graph. I think the anomalies may have occurred because our battery pack broke and we had to get a replacement. Apart from the battery pack everything else went safely and well. Our preliminary experiments allowed us to make sure the wire did not get too hot which meant we did not get any anomalies around 100mm and that we were safer. I think our range was big enough but if we had more time I would have liked to done another repeat and possibly take measurements at 50mm intervals to achieve a greater range of results.I thought our results were really good they clearly supported our prediction that as length increases so does resistance. If I was to further this experiment I would use different metals and see which had the best resistivity, I would not use a metre rule because it was easy for human error to occur as it was not particularly detailed perhaps a digital measuring device would have been better. I might also try a different variable such as diameter of wire to see how that affected the resistance. Overall I was very pleased with our investigation and think that we did all we could to do it well.

Caprivis new course Essays - Zambezi Region, German Empire

Caprivi's new course Essays - Zambezi Region, German Empire Caprivi's new course Caprivi?s new course The Kaiser had been so taken by the success of tariff reform that Caprivi had been given the noble title of count. However, powerful voices quickly and effectively raised doubts: Court conservatives. To start with, Wilhelm 11 himself backed Caprivi?s social policy in the belief that the improvements would discourage people from supporting the socialists. Yet, Wilhelm 11 sympathy began to wane and many of Wilhelm?s advisers at court disagreed with caprivi?s socialist policies. Some encouraged the Kaiser to ditch him and to assume a more authoritarian personal rule. Moving on and the landowners were deeply upset by the commercial treaties since they threatened to reduce their profits. In 1893 the Agrarian league was formed to put pressure on parliament and to win support and privileges for landowners. It quickly grew into an effective and well organised lobby of a third of a million members that acted as a powerful pressure group on behalf of the conservative parties. Finally in 1893 t here had been resentment in military circles when Caprivi made concessions over the army Bill in the Reichstag by reducing the length of conscription for national service from three years to two. The army bill was actually rejected, resulting in the Reichstag being dissolved and the following election brought things to a head. There were conservative concerns about anarchist outrages across Europe and the increase in the total number of social democrat seats to 44. Opponents of Caprivi now reinforced Wilhelm11 own doubts about his chancellor?s suitability for office and Wilhelm11 pressed Caprivi to draw up an anti-socialist subversion bill. The chancellor refused and this led to an extraordinary plan by Wilhelm11 and his supporter Eulenburg. Their plan was to set aside the powers of the Reichstag, crush socialism and establish a more authoritarian system centred on the Kaiser himself. This was the final straw for caprivi. He successfully talked the Kaiser out of such a course of act ion, but he had lost the will to carry on. In October 1894 caprivi resigned and gladly retired from the political scene. Caprivi?s four years as chancellor neatly illustrate the difficulties of trying to cope with the pressures of the various political forces in imperial Germany. In his attempt to create a genuine base of parliamentary support for the government, Caprivi showed his understanding of the need, in a modern industrial society, for a political approach that recognised the concerns and aspirations of the mass of the population. However, Caprivi?s new course foundered because it was opposed to established forces of power and influence. He was subjected to considerable abuse from the conservative press and he was the focus of opposition intrigue at court. In the end, he could not rely on the consistent support of the Kaiser whose delusions of greatness were now taken up with thoughts of personal rule and weltpolitik.

Personal leadership Essay Example | Topics and Well Written Essays - 1250 words

Personal leadership - Essay Example One of the most notable things about this individual was how they learned to lead. While a handful of managers at the restaurant had experience in hospitality management from formal training, this particular manager had learned his management skills from on the job work. In these regards, his skill-set stood out slightly from managers that had the formal background and in some instances one could detect a slight sense of superiority from those that had actually gone through formal schooling. Instead, this manager had begun his career as a host in one of the less populated restaurants, and later moved to serving. As he succeeded at these positions upper level management soon offered him a managerial position at that particular restaurant; after succeeding at this restaurant he transferred to the larger restaurant, where I came into contact with him. Consider this brief background account, it’s clear that the individual developed their leadership and managerial skills from in-ho use interactions and personal life experience rather than formal training. In examining his leadership skills this was evident as there seemed to be a greater level of understanding, efficiency, and empathy with the employees and business practices than the managers that predominantly had formal training. In terms of defining leadership there are a number of issues that must be considered in relation to this individual’s philosophy. While some my disregard the insight that can be gleamed from the perspective of a restaurant manager, this paper argues that in actuality this perspective is highly relevant to nearly all forms of business as it consists of a combination of a variety of class understandings. For instance, the restaurant provides a solid combination of lower, middle, and upper class patrons that must be considered and negotiated with; there is also a highly diverse workforce, with different ages and nationalities that must be managed. In these respects the position demands a highly malleable individual. In terms of this man’s leadership philosophy it was clear that he adopted a policy of mutual respect for employees. He treated all individuals equitably and had a general understanding demeanor. If there were any specific leadership philosophies embodied in his approach I believe they would generally be linked to this element as a base factor. Extending beyond the equitable treatment of employees and customers there were a number of elements within his treatment of employees that were highly notable. In terms of new employees he was understanding and open, allowing them to develop in a constructive and not overly critical way. In terms of experienced employees his approach was one wherein rather than having to demand respect through professional rank, he gained respect by being a reliable and efficient employee. In very few instances was there employee disrespect, as the general consensus in regards to his leadership approach was positi ve. In achieving this level of respect it was clear that it was accomplished through his daily actions. For example, he always showed up for work on time and was highly efficient in terms of restaurant tasks. One such skill was his ability to route food orders to the specific waiters and ensure the food arrived at the table in a timely way. Another skill was being able to speak with all customers on a level that made them feel comfortable with his