Procurement Strategy Supply Chain Management - 1170 Words

1 Introduction Procurement strategy is the important strategy involve the supply chain management, It provides the business could access the opportunities to reduce the cost, makes the quality promise, consequensely, gain the profit. The supplier selection process starts with the requirements of the materials for the business. The processes of the supplier selection include supplier identification, supplier evaluation and set the contract with the supplier. Supplier selection is designed to ensure their quality, safety and efficiency. 2 The main body 2.1 Supplier selection process 2.1.1 supplier identification At first, the business must identify potential suppliers applied to the procurement strategies as described in the procurement†¦show more content†¦Green Chilly has to analyze all the information together about potential suppliers. Generally, the business make 3 types of request to suppliers, request for information(RFI), request for proposal(RFP), request for quote(RFQ), (Beil and Ross, 2009) the suppliers must give the response according to these three requests. There are more complex factors take into consideration to select the suppliers, such as environmental, social, political, and customer satisfaction. It is important to identify the requirement and the criteria for the different types of the supplier in the business, the quality and the price is widely used in the supplier selection, according to the Green Chilly restaurant, the criteria can be divided into the food supplier and nonfood supplier, because of the restaurant request a high requirement for the fresh foo d, delivery is the most important factors to consider, the non-monetary term is applied to the food supplier. The equipment in the restaurant could use the monetary criteria to reduce the cost. Additionally the supplier s operational capacity, technical capability and financial ability should be taken under consideration (Solish and Semanik 1999). 2) Determine Sourcing Strategy . It is important to determine the sourcing strategies,

Short Story My Genre - 1356 Words

Short Story My genre is a short story. The length is around 10 to 25 pages usually. With around 1500 to 2500 words. Short stories started around the 15th century, In the medieval period. Short stories were used as entertainment and also used to annotate history and beliefs. Short stories are basically a story focused on one point. Everything is based of on one single structure or event, and everything goes on around it. For example, if you are aiming at a target, instead of looking around it, you will look straight in the middle where you re going to aim and nowhere else. This is how you write a short story. Some of the characteristics of a short story are that, they are less complex than a novel, single setting, and fewer characters. The narrative modes will never change, a person can use first person, second person and if needed third-person point of view. Furthermore, if the author wants to change a few things, he can do it because a short story doesn t have any specific set of rules. The cha racteristic usually just helps the author to start a story, but no one has to follow those rules. The context of a short story is pretty much a summary of the whole story in a few sentences. The audience can be anyone from a child to an adult.depending on who the author wanted to read his or her story. If the story was made for little kids than anyone could read it people such as teachers, students, kids and parents. If the book was made for a college class than the audienceShow MoreRelatedThrough My Creative Writing And Reading Experience, I Have1156 Words   |  5 PagesThrough my creative writing and reading experience, I have been exposed to a variety of literary genres. My preferred genres have consistently been free verse poetry, fiction, and non-fiction. For the purpose of this class, I have chosen the genre of creative non-fiction. 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The critical essay â€Å"Haunted House/Haunted Heroine: Female Gothic Closets in â€Å"The Yellow Wallpaper†Ã¢â‚¬  by Carol Margaret Davison is an analysis of the short story, focusing on the genre of female gothic and the themes of loss of identity, self discovery, the darkRead MoreWriting Strategies : Developing Believable Characters And Writing Drafts Essay1283 Words   |  6 PagesThe two main writing strategies my placement has focused on thus far, are developing believable characters and writing drafts. To develop characters, we have taught the students to use the skills they learn in their reading lessons, and transform them onto the pages of their notebook. As mentioned, we have been working on identifying, and empathizing, with characters in reading. These same skills are needed for both reading about and writing about characters. 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Human rights in kuwait Essay Example For Students

Human rights in kuwait Essay Human Rights: Yet another commodity for the new society or a necessity? As one stands on the doorsteps of a new millennium, one can only imagine the future ahead. With the globalization movement making its way around the world, issues such as human rights are coming up, and are becoming international issues of concern rather than local ones. International organizations monitor governments and note the extent to which those governments adhere to and respect human rights. In the age of globalization, free trade between the nations of the world exists along with a sizeable transfer of knowledge and technology. And for one nation to succeed in that new environment it must have positive relations with others. For this good relation to evolve and develop, a nation must first address its inner issues of which human rights is a part of, for the human factor is prime in the globalization age that is based mainly on human-brain based industries. The Director of the Kuwait Information Office in Washington, in a lecture at Georgetown University, said, The democratic process taking place in Kuwait is compatible with the Western definition of democracy, and it is clear when tracing countrys modern history that there is in fact a true democratic process presently sweeping the country.; In 1948, the United Nations adopted the ;Universal Declaration of Human Rights; which included the minimum requirements that nations around the world must aim for to achieve and maintain mans fundamental freedoms and rights. This included principles of equality without regard to race, color, sex, language, religion etc. in addition to the right to life, liberty and security. The Declaration was the platform on which all people should act. Any breach of its articles would put the breaching Nation under great pressure and criticism from its peers, who usually aim to correct the situation. Al-Ghabra added, It has become increasingly difficult to maintain authortarian government in the modern era. By 1997, more that 116 nations had a president chosen by elections, up from only 39 nations in 1974. In the middle eastern nation of Kuwait, human rights have come a long way towards achieving a formidable status for the 38 years old nation has taken measures that surpass those taken by older nations. Kuwaits constitution that dates back to the year 1962 ensured human rights in many of its articles. Kuwaiti Parliament member AbdulMohsen Jamal said that the constitution is a, ; great achievement that has gained Kuwait the respect of the international community. ; The constitution took a humanitarian capitalistic approach towards dealing with citizens and society. It based national economy on social justice and equal cooperation between public and private sectors aiming to achieve economic development and a better standard of living for its citizens. The constitution allocated a full chapter that deals with rights and public duties, guaranteeing personal freedom, freedom of religion, press and gathering, and the right to education and work. Article 6 states that Kuwait is a democratically ruled nation. Article 7 states that freedom and fairness are the basic principles of society where cooperation and mercifulness is the closest tie between citizens. Article 8 deals with providing security and opportunities by the nations government. Article 29 states that all people are equal in their responsibilities and public duty without indifference due to race, sex, language or religion. Article 30 states that personal freedom is guranteed. Article 35 provides for freedom of religions. Article 43 deals with the freedom to establish non governmental organizations on national basis using peaceful means adopted by law. Article 80 states that a parliament is made up of 50 members elected by the people. In addition to its constitution, Kuwait has signed most international treaties that deal with human rights such as treaty against all forms of discrimination against women, treaty for kids rights, treaty against torture, and was the first Arabian Gulf country to ratify the two international treaties formulated by the International Committee for Human Rights in 1954 called the International Covenant on Economic, Social and Cultural Rights and the International Covenant on Civil and Political Rights. Martin Luther Essay Summary With a firm basis, Kuwait took a step further in 1999 when the Amir signed a decree giving women in Kuwait the right to vote and run for .

The Crusades A History, Second Edition Essay Sample free essay sample

The Crusades were a critical chapter in European and Christian history. deeply impacting the times in which they occurred. every bit good as the hereafter of Christianity itself. Jonathan Riley-Smith’sThe Crusades– about 400 pages in length – provides a extremely elaborate history of all the campaign motions that took topographic point. Written by Riley-Smith. writer and editor of several books on the Crusades and the Middle Ages in general. the book is composed of two forewords. an debut. 10 chapters. and closes with an afterword. The meat of the book is the 10 chapters. each of which is broken down into several subdivisions. therefore leting for a elaborate analysis of every facet of each campaign. The first two chapters provide an history of the events taking up to the start of the campaign motion. every bit good as an in-depth focal point on the first campaign itself. Riley-Smith makes it clear that the intent of this first campaign was to salvage the Holy Land from the heathen Muslims. We will write a custom essay sample on The Crusades: A History, Second Edition Essay Sample or any similar topic specifically for you Do Not WasteYour Time HIRE WRITER Only 13.90 / page He emphasizes the point that the campaign was to be about release. non merely for the Holy Land. but besides for all those who were evildoers. If they fought for the release of Jerusalem. they would see religious release. The 3rd and 4th chapters focus on the colony. development. and defence of the Latin East. Riley-Smith provides an account of the events following the first campaign. which ended in triumph for the reformers. They were able to set up little provinces. of which they were the exclusive swayers. However. this would merely last for a brief period of clip. as the tensenesss that led to the campaign were still simmering. Those tensenesss lead Riley-Smith to discourse the slightly forgettable 2nd campaign in the 5th chapter. He emphasizes that hapless executing resulted in low morale among the reformers. which in bend led to really few triumphs during that peculiar campaign. He besides makes the point that. at this phase. the fighting motion was in a period of adolescence. Like all striplings. it was traveling through the awkward stage. but it would come of age with the 3rd campaign. The 6th chapter covers the 3rd. 4th. and 5th campaigns. every bit good as the children’s campaign and other minor campaigns led by single swayers. This chapter shows the growing that the fighting motion experienced. every bit good as the seeds of its eventual death. The 7th chapter continues in the same yarn as the old 1. supplying histories of fighting motions in Spain. Prussia. and Livonia. every bit good as campaigns launched by St. Louis of France. It closes with a treatment refering why there was no great fighting motion following 1276. The eight chapter focuses one time more on the Latin East. discoursing the assorted political developments happening at that place between 1192 and 1291. The concluding two chapters discuss the assorted developments within the crusading motion itself. every bit good as the ultimate death of the fighting motion. Despite what most history books province. the fighting motion did non stop with the last official campaign. but instead died a slow decease. non petering out until the late 1790s. Finally. the afterword brings the book to a stopping point. It provides treatments how different groups have viewed and explained the significance of the fighting motion. every bit good as the consequence the motion had on the survey of history. and history in general. Upon completion of the book. it becomes evident that. while it is rather detailed in its history of the full crusading motion. it is a slightly dry read. There are intimations of wit. but for the bulk of the book. the information is presented in simple narrative. However. one redeeming quality is the use of maps. which enable the reader to hold a ocular to travel along with the narrative. This book would be an first-class tool for a class that focused merely on the Crusades. but for merely reading for personal enjoyment. it would be a spot hard to acquire through. Despite these little drawbacks. the existent format of the book is rather good. The linguistic communication is straightforward. and slightly simple to read. However. the great sum of item can be a spot dashing for those merely seeking a general history of the fighting motion. Overall. Riley-Smith accomplishes the undertaking he set out: to supply the reader with an in-depth account and analysis of the fighting motion. His huge cognition of the Crusades. every bit good as the period of the Middle Ages in general. are what allow this book to be a success.

Understanding Induction Motor Nameplate Information Essay Example

Understanding Induction Motor Nameplate Information Essay Keeping the language common among manufacturers is critical to making motors interchangeable The U. S. motor industry has worked on a standardized basis for more than three-quarters of a century. The standardization agency — National Electrical Manufacturers Association (NEMA) — was established in 1926 â€Å"†¦ to promote the standardization of electrical apparatus and supplies. † As a result of this groups efforts, you can expect â€Å"standard† motors from different manufacturers to meet or exceed minimum performance parameters and, for the most part, be about the same size. A critical part of making motors interchangeable is ensuring that nameplate information is common among manufacturers. The common language of the motor nameplate enables installation and maintenance personnel to quickly understand and recognize exactly what type of motor theyre dealing with during a new installation or replacement procedure. The NEC states that the motor nameplate must show the following information: * Rated voltage or voltages * Rated full-load amps for each voltage level * Frequency * Phase * Rated full-load speed * Insulation class and rated ambient temperature Rated horsepower * Time rating * Locked-rotor code letter * Manufacturers name and address In addition to this required information, motor nameplates may also include data like frame size, NEMA design letter, service factor, full-load efficiency, and power factor. Finally, some nameplates may even include data like bearing identification numbers, certification code, manufacturer serial number, and symbols a nd logos. Basic nameplate data. In order to fully understand the details presented on motor nameplates well examine each of these items more closely and explain its importance. We will write a custom essay sample on Understanding Induction Motor Nameplate Information specifically for you for only $16.38 $13.9/page Order now We will write a custom essay sample on Understanding Induction Motor Nameplate Information specifically for you FOR ONLY $16.38 $13.9/page Hire Writer We will write a custom essay sample on Understanding Induction Motor Nameplate Information specifically for you FOR ONLY $16.38 $13.9/page Hire Writer Rated voltage  Ã¢â‚¬â€ Motors are designed to yield optimal performance when operating at a specific voltage level, or a combination of voltage levels in the case of dual-voltage or tri-voltage motors. This value is known as the nameplate voltage. In recognition of the fact that voltage changes on your power distribution system occur due to changing load conditions within your facility and on the utility supply that feeds your facility, motors are designed with a 10% tolerance for voltage above and below the rated nameplate value. Thus, a motor with a rated nameplate voltage of 460V should be expected to operate successfully between 414V and 506V. Rated full-load amperage  Ã¢â‚¬â€ As the torque load on a motor increases, the amperage required to power the motor also increases. When the full-load torque and horsepower is reached, the corresponding amperage is known as the full-load amperage (FLA). This value is determined by laboratory tests; the value is usually rounded up slightly and recorded as the nameplate value. Rounding up allows for manufacturing variations that can occur and some normal voltage variations that might increase the full-load amps of the motor. The nameplate FLA is used to select the correct wire size, motor starter, and overload protection devices necessary to serve and protect the motor. Frequency  Ã¢â‚¬â€ To operate successfully, the motor frequency must match the power system (supply) frequency. In North America, this frequency is 60 Hz (cycles). In other parts of the world, the frequency may be 50 or 60 Hz. Phase  Ã¢â‚¬â€ This concept is fairly simple in the United States. You either have a single-phase or 3-phase motor. Rated full-load speed  Ã¢â‚¬â€ This is the motors approximate speed under full-load conditions, when voltage and frequency are at the rated values. A somewhat lower value than the actual laboratory test result figures is usually stamped on the nameplate because this value can change slightly due to factors like manufacturing tolerances, motor temperature, and voltage variations. On standard induction motors, the full-load speed is typically 96% to 99% of the no-load speed. Insulation class and rated ambient temperature  Ã¢â‚¬â€ A critical element in motor life is the maximum temperature that occurs at the hottest spot in the motor. The temperature that occurs at that spot is a combination of motor design (temperature rise) and the ambient (surrounding) temperature. The standard way of indicating these components is by showing the allowable maximum ambient temperature, usually 40 °C (104 °F), and the class of insulation used in the design of the motor. Available classes are B, F, and H. Rated horsepower  Ã¢â‚¬â€ Horsepower is the measure of how much work a motor can be expected to do. This value is based on the motors full-load torque and full-load speed ratings and is calculated as follows: Horsepower (hp)=[Motor Speed? Torque (lb-ft)]? 5,250 The standardized NEMA table of motor horsepower ratings runs from 1 hp to 450 hp. If a loads actual horsepower requirement falls between two standard horsepower ratings, you should generally select the larger size motor for your application. Time rating  Ã¢â‚¬â€ Standard motors are rated for continuous duty (24/7) at their rated load and maximum ambient temperature. Specialized motors can be designed for â€Å"short-time† requirements where intermittent duty is all thats needed. These motors can carry a short-time rating from 5 minutes to 60 minutes. The NEMA definition for short-time motors is as follows: â€Å"All short-time ratings are based upon corresponding short-time load tests, which shall commence only when the windings and other parts of the motor are within 5 °C of the ambient temperature at the time of the test. † By using short-time ratings, its possible to reduce the size, weight, and cost of the motor required for certain applications. For example, you may choose to install an induction motor with a 15-minute rating to power a pre-operation oil pump used to pre-lube a gas turbine unit because it would be unusual for this type of motor to be operated for more than 15 minutes at a time. Locked-rotor code letter  Ã¢â‚¬â€ When AC motors are started with full voltage applied, they create an inrush current thats usually many times greater than the value of the full-load current. The value of this high current can be important on some installations because it can cause a voltage dip that might affect other equipment. There are two ways to find the value of this current: * Look it up in the motor performance data sheets as provided by the manufacturer. It will be noted as the locked-rotor current. * Use the locked-rotor code letter that defines an inrush current a motor requires when starting it. Manufacturers name and address  Ã¢â‚¬â€ Most manufacturers include their name and address on the motor nameplate. Optional nameplate data. In addition to the required items noted above, more information is typically included on a motor nameplate. Frame size  Ã¢â‚¬â€ Under the NEMA system, most motor dimensions are standardized and categorized by a frame size number and letter designation. In fractional horsepower motors the frame sizes are two digits and represent the shaft height of the motor from the bottom of the base in sixteenths of an inch. For example, a 56-frame motor would have a shaft height (â€Å"D† dimension) of 56/16 of an inch, or 3. 5 inches. On larger 3-digit frame size motors, 143T through 449T, a slightly different system is used where the first two digits represent the shaft height in quarters of an inch. For example, a 326T frame would have a â€Å"D† dimension of 32 one-quarter inches, or 8 inches. Although no direct inch measurement relates to it, the third digit of three-digit frame sizes, in this case a 6, is an indication of the motor bodys length. The longer the motor body, the longer the distance between mounting bolt holes in the base (i. e. greater â€Å"F† dimension). For example, a 145T frame has a larger F dimension than does a 143T frame. When working with metric motors (IEC type), the concept is the same as noted above with one exception — the shaft height above the base is now noted in millimeters rather than inches. The frame size is the shaft height in millimeters. NEMA design letter  Ã¢â‚¬â€ Certain types of machinery may require motors with specialized performance characteristics. For example, cranes and hoists that have to start with full loads imposed may require motors with operating characteristics much different from what is required for pumps and blowers. Motor performance characteristics can be altered by design changes in lamination, winding, rotor, or any combination of these three items. Most standard motors for general-purpose applications meet or exceed the values specified for Design B motors in NEMA MG-1, Standard for Motors and Generators. Design A motors are sometimes used on applications that require high breakdown (pull-out) torque, such as injection molding machines. Design C motors are selected for applications that require high starting (locked-rotor) torque, such as inclined conveyors. Design D motors, also called â€Å"high slip† motors, are sometimes used to power hoists and cycling loads, such as oil well pump jacks and low-speed punch presses. Fig. 1. These graphs show typical torque-speed curves for Design A, B, C, and D motors. Fig. 1  shows the general shape of torque-speed curves for motors with NEMA Design A, B, C, and D characteristics. Bear in mind that the curves shown in Fig. 1 and the figure in the sidebar on page 24 are general shapes. In real motors, each motor would have its own distinct values different from the percentages reflected in these figures. Service factor  Ã¢â‚¬â€ Service factor (SF) is an indication of how much overload a motor can withstand when operating normally within the correct voltage tolerances. For example, the standard SF for open drip-proof (ODP) motors is 1. 15. This means that a 10-hp motor with a 1. 15 SF could provide 11. 5 hp when required for short-term use. Some fractional horsepower motors have higher service factors, such as 1. 5, 1. 35, and even 1. 50. In general, its not a good practice to size motors to operate continuously above rated load in the service factor area. Motors may not provide adequate starting and pull-out torques, and incorrect starter/overload sizing is possible. Traditionally, totally enclosed fan cooled (TEFC) motors had an SF of 1. 0, but most manufac turers now offer TEFC motors with service factors of 1. 15, the same as on ODP motors. Most hazardous location motors are made with an SF of 1. 0, but some specialized units are available for Class I applications with a service factor of 1. 5. Full-load efficiency  Ã¢â‚¬â€ As energy costs have increased, conservation efforts have become more important to commercial and industrial operations. As a result, its become important to have full-load efficiency information readily available on motor nameplates. The efficiency is given as a percentage and indicates how well the motor converts electrical power into mechanical power. The closer this value is to 100%, the lower the electricity consumption cost is going to be. Generally, larger motors will be more efficient than smaller motors. Todays premium efficiency 3-phase motors have efficiencies ranging from 86. 5% at 1 hp to 95. 8% at 300 hp. The efficiency value that appears on the nameplate is the nominal full-load efficiency as determined using a very accurate dynamometer and a procedure described by IEEE Standard 112, Method B. The nominal value is what the average would be if a substantial number of identical motors were tested and the average of the batch were determined. Some motors might have a higher value and others might be lower, but the average of all units tested is shown as the nominal nameplate value. Guaranteed minimum is another efficiency thats sometimes noted on a nameplate. This value is determined from a mathematical relationship that assumes that the worst efficiency of any motor in the batch — used to determine the average (nominal) value — could have losses as much as 20% higher than the average. As a result, each nominal efficiency value would have a corresponding minimum efficiency value. You can view these values in Table 12-8 in NEMA MG-1. Power factor  Ã¢â‚¬â€ Power factor is the ratio of motor load watts divided by volt-amps at the full-load condition. Power factor for a motor changes with its load. Power factor is minimum at no load and increases as additional load is applied to the motor. Power factor usually reaches a peak at or near full load on the motor. Final spin. Changing motors out becomes a lot easier when you can quickly recognize the key items that describe a motors size, speed, voltage, physical dimensions, and performance characteristics. All of this information and more is usually available on the motors nameplate. Its your responsibility to be able to correctly interpret the information on this nameplate, correctly apply it in the field, and verify conformance to NEMA, IEC, or other industry standards. Editors Note:  This text was written by Ed Cowern when he was a district manager for Baldor Electric Co. in Wallingford, Conn. He has since retired. Sidebar: The Delicate Relationship of Motor Speed and Torque This is a typical torque-speed curve for a standard AC induction motor. Its important to understand some details of motor performance as shown by a typical Torque-Speed curve in the  Figure  to the right. The plot shows what happens in terms of output torque and motor speed when a motor is started with full voltage applied. The motor is initially at zero speed and develops locked-rotor torque (Point A). As the motor accelerates, some motor designs produce a slight dip in torque. If they do, the lowest point on this curve is called the pull-in or pull-up torque (Point B). As the speed increases further, the torque generally increases to the highest point on the curve (Point C), which is called the pullout or breakdown torque. Finally, when the motor is loaded to its full-load torque, the motor speed stabilizes (Point D). If the motor isnt driving anything, its speed goes up to its no-load speed or synchronous speed (Point E). For example, on a four-pole motor operating at 60 Hz, the no-load speed might be 1,799 RPM and synchronous speed would be 1,800 RPM. Each of these points (A, B, C, and D) has absolute values (usually expressed in pound-feet). However, theyre frequently given in terms of a percentage of the full-load torque. For example, a 20-hp, 60-Hz, four-pole motor could have a full-load torque of 59. 5 pound-feet and a locked-rotor torque of 116 pound-feet. This is shown as: (116? 59. 5)? 100=195% Similarly, the breakdown torque of 199 pound-feet could be shown as: (199? 59. 5)? 100=334%

Experiment to investigate the Factors affecting the Energy Transfer Involved in the Cooling of Water Essays

Experiment to investigate the Factors affecting the Energy Transfer Involved in the Cooling of Water Essays Experiment to investigate the Factors affecting the Energy Transfer Involved in the Cooling of Water Essay Experiment to investigate the Factors affecting the Energy Transfer Involved in the Cooling of Water Essay Water cools in many different ways due to a variety of different reasons, which depend on the way in which the water is contained. I will be considering how water in a plastic cup cools. If I put hot water in a plastic cup I would expect heat to be lost by radiation from the sides and the top, conduction through the base and evaporation from the top. If however, the sides and base were highly insulated; most heat would be lost by evaporation and radiation from the top. Here are the ways in which heat is lost from cooling water: 1) Radiation Radiation is the movement of heat energy by electros of radiation are the sun radiating heat through space and a central heating radiator radiating heat into a room. 2) Conduction Conduction can take place in solids, liquids and gases. When a material is heated the particles nearest to the heat gain kinetic energy. They then start to vibrate faster due to this energy and as they do they touch other particles and transfer the kinetic energy to them. This process is repeated and the energy is transferred through out the object from hot regions to cooler regions. As the water looses heat from the sides of the cup conduction will cool the mass of the water. Conduction will also occur through the walls of the cup and then radiate and through the base of the cup into the surface on which the cup stands. 3) Convection When a liquid of gas is heated (convection can not take place in solids), the molecules move faster and push each other further apart. The fluid expands and becomes less dense. The less dense fluid then rises upwards taking its thermal energy with it. This rising fluid is then replaced by cooler fluid and a convection current is set up. Thermal energy is transferred by the molecules themselves moving from the hot region to the cooler one. As the water nearest the sides of the plastic cup cools due to radiation, convection with in the water will cool all the water. 4) Evaporation When water is heated the molecules gain kinetic energy and move around very quickly. Some of these molecules manage to gain enough energy to break free from the liquid. This process is called evaporation. As the water evaporates it takes away some of the thermal energy. As the temperature of water increases the molecules gain more and more energy so the rate of evaporation also increases. Evaporation can be reduced by sealing the top of the plastic cup with a very small air space above the water. The water vapour will then condense and drip back into the water. 5) Temperature differential The difference in temperature between room temperature and the temperature of water can alter the rate of which the water cools. If there is a big difference and the water is very hot and the room temperature is fairly low then the rate of cooling will be much larger than if the temperatures were very close together. 6) Insulation Insulation is a material with low conductivity which is used to reduce the amount of heat lost from a hot object such as a hot water tank. By wrapping the plastic cup with insulation the rate of conduction through the wall of the cup will be reduced. Air is a very good insulator and so many insulators have small air pockets with in them which can prevent large convection currents being set up. 7) Energy The thermal energy of water can be calculated by measuring the volume of water and its temperature. The energy change = the specific heat capacity à ¯Ã‚ ¿Ã‚ ½ mass à ¯Ã‚ ¿Ã‚ ½ temperature change The specific heat capacity of water is 4200 Joules per Kg per à ¯Ã‚ ¿Ã‚ ½K For example to heat up 1kg of water by 10 à ¯Ã‚ ¿Ã‚ ½C would require: 4200 à ¯Ã‚ ¿Ã‚ ½ 1à ¯Ã‚ ¿Ã‚ ½ 10 = 42000 Joules. The energy loss can then be calculated by measuring the reduction in temperature provided the volume of water remains unchanged. Plan I have chosen to investigate the effect of insulation on the rate of energy loss from the water because it is more easily measured than the other factors. By increasing the thickness of insulation surrounding the water, I can measure the rate at which heat is lost from the water for different thicknesses and determine the relationship between the rate of heat loss and the thickness of insulation. To do this I will need to reduce the loss of heat by evaporation by sealing the top of the container. In this experiment heat will be conducted through the insulation and then radiate into the air. The amount of radiation will change because the surface temperature of the insulation will reduce as the insulation becomes thicker and the external surface area of the insulation increases due to the extra thickness around a circular cup. Experiment to investigate the effect of insulation on the rate of heat loss from a plastic cup of water Aim: To investigate the change in the rate of heat loss from a plastic cup by varying the thickness of insulation surrounding the cup and to see if there is a relationship between the rate of heat loss and the thickness of insulation. Apparatus Item Purpose Plastic cup To contain the water Thermometer To measure the temperature of the water Digital Timer To allow measurement of the temperature at regular intervals Kettle To heat the water Measuring cylinder To measure the quantity of water Expanded polystyrene sheet insulation used for lining walls under wallpaper. 2mm thick To wrap around the cup in layers to insulate it Cling film To seal the top of the cup from evaporation Sellotape To hold the insulation around the cup Clamp stand and cotton To suspend the thermometer in the water so that it does not touch the sides or bottom Foam mat 20mm thick To stand the cup on so that heat is not lost through the base Water Ruler To measure thickness of 10 layers of insulation to determine the average thickness. Preliminary experiment In order to determine the probable range of results it was necessary to carry out a preliminary experiment by filling the plastic cup with water and measuring how long it took to cool. The following information was found. 1. The quantity of water to fill the cup to leave only a small air space at the top. 2. The starting temperature of the water in the cup was found to be about 85à ¯Ã‚ ¿Ã‚ ½C so it was decided to start reading the temperatures once the temperature had fallen to 80à ¯Ã‚ ¿Ã‚ ½C 3. It as found that it took about 25 minutes for the temperature to fall to 60à ¯Ã‚ ¿Ã‚ ½C with no insulation. With thick insulation it would take much longer so it was decided to monitor the temperature for 30 minutes to give a good range of results. 4. It was found that it would be sufficient to take readings at one minute intervals. Otherwise at high levels of insulation the variation in temperature would be very small. 5. It was found that it was possible to measure read the temperature on the thermometer to an accuracy of about 0.25 C. 6. The preliminary experiment confirmed that the set up of the apparatus was correct with the thermometer at the right level and easy to read and that using a digital clock it was possible to time the readings accurately. Prediction I would expect that the rate at which the water cools to reduce as the insulation becomes thicker. While insulation is supposed to stop heat loss it will still act as a conductor of heat. The amount of energy transferred through a conductor is proportional to the thermal gradient. By doubling the thickness of insulation the thermal gradient is halved. So I would expect the energy lost though the insulation to reduce to half. Insulation has a strength to prevent heat loss which is measured as its U value. The U value is measured as Watts per mà ¯Ã‚ ¿Ã‚ ½ per à ¯Ã‚ ¿Ã‚ ½C and is for a given thickness of insulation. Double the thickness and the U value will halve. Rate of heat loss = U value à ¯Ã‚ ¿Ã‚ ½ surface area à ¯Ã‚ ¿Ã‚ ½ temperature difference. So if the insulation doubles in thickness, the U value will halve and the rate heat loss will halve. Diagram Method Room temperature was taken using the thermometer which had been allowed to adjust to the room temperature and this was recorded. The apparatus was arranged so that a plastic cup stood on a layer of foam insulation with a thermometer suspended from a clamp stand so that the bulb of the thermometer would be hung in the middle of the water in the cup. For the first test no insulation was wrapped around the cup. For the later tests, layers of insulation were tightly wrapped around the cup using sellotape so that once the air was trapped between them none could escape. This was also done to the base of the cup. The kettle was boiled and 150mlà ¯Ã‚ ¿Ã‚ ½ of hot water was measured out using the measuring cylinder. This was then poured into the plastic cup. A piece of cling film was then stretched over the top of the cup to form a seal so that no evaporated water could escape. Square pieces of insulation (bigger than the cup) were placed on top of the cup. The number of squares depended on the number of layers of insulation being tested. A hole was pierced through the centre of the lid. A thermometer was then suspended using cotton and the clamp stand and then pushed through the hole so that the end hung in the centre of the cup. The lid was then taped down securely. When the temperature had fallen to 80 à ¯Ã‚ ¿Ã‚ ½C, the stop clock was started and the temperature of the water was taken every minute for 30 minutes. The results were recorded. After the first test, the cup was emptied and two layers of insulation were fixed around the cup as described above. The test was then repeated for the two layers of insulation. Further tests were then carried out for 4, 6, 8 and 10 layers of insulation. All results were recorded. Room temperature was taken again at the end of the experiment to see if it had varied. The average thickness of the insulation was measured by measuring 10 layers and dividing the result. Fair test * The thermometer was suspended so that it did not touch the sides of the cup so that the reading was the temperature of the centre of the water. * Taking room temperature before and after the experiment to see if there had been any change which would affect the results of the experiment. * The same volume of water was used in each test. * The layers of insulation were fixed in the same way by the same person each time. * By repeating the test for a wide range of thicknesses of insulation anomalies would show up as the results are plotted. Safety * Safety glasses were worn to protect our eyes from splashes of hot water. * Gloves were worn to protect hands from the hot water * Laboratory coats were worn to help protect our bodies from the hot water. * We stood up so that if the water did spill we could move away quickly * The experiment was done under supervision. * The thermometer was suspended so that there was no risk of dropping it. * The apparatus was set up in a position where it could not easily be knocked over. Results Room temperature at start of experiment = 22.5à ¯Ã‚ ¿Ã‚ ½C Room temperature at end of experiment = 23.0à ¯Ã‚ ¿Ã‚ ½C Table 1 Temperature change for varying thicknesses of insulation. Time in Minutes Temperature in à ¯Ã‚ ¿Ã‚ ½C Layers 0 layers 2 layers 4 layers 6 layers 8 layers 10 layers 0 80.00 80.00 80.00 80.00 80.00 80.00 1 78.50 79.75 80.00 79.00 80.00 79.25 2 77.00 79.00 79.25 78.75 79.00 78.50 3 76.00 78.50 78.75 78.25 78.75 78.00 4 75.25 77.75 78.25 78.00 78.50 77.50 5 74.25 77.25 78.00 77.50 78.00 77.25 6 73.00 76.75 77.25 77.00 77.75 76.75 7 72.50 76.25 77.00 76.75 77.23 76.50 8 71.75 75.75 76.50 76.50 77.00 76.00 9 70.75 75.25 76.00 76.00 76.75 76.00 10 70.00 75.00 75.50 75.75 76.25 75.50 11 69.25 74.50 75.00 75.25 76.00 75.00 12 68.50 73.75 74.75 75.00 75.75 75.00 13 68.00 73.25 74.50 74.75 75.25 75.00 14 68.00 72.75 74.00 74.50 75.00 74.25 15 66.00 72.25 73.50 74.00 75.00 74.00 16 65.25 71.75 73.00 73.50 74.75 73.75 17 65.00 71.25 72.76 73.25 74.25 73.50 18 64.25 70.75 77.25 73.00 74.00 73.25 19 63.50 70.25 72.00 72.50 73.75 73.00 20 63.00 70.00 71.50 72.00 73.50 72.75 21 62.25 69.50 71.00 72.00 73.00 72.50 22 62.00 69.00 70.75 71.50 73.00 72.25 23 61.00 68.50 70.25 71.00 72.75 72.00 24 60.25 68.00 70.00 71.00 72.50 71.75 25 60.00 67.50 69.75 70.50 72.00 71.25 26 59.50 67.00 69.50 70.00 72.00 71.00 27 58.75 66.75 69.00 70.00 71.75 71.00 28 58.00 66.00 68.75 69.75 71.25 70.75 29 57.50 65.75 68.50 69.50 71.00 70.50 30 57.00 65.25 68.00 69.00 71.00 70.25 Energy loss after 30 minutes in Joules 14490 9292 7560 6930 5670 6142 Table 2 Temperature change at 10 minute intervals Time in Minutes Temperature in à ¯Ã‚ ¿Ã‚ ½C Layers 0 layers 2 layers 4 layers 6 layers 8 layers 10 layers 10 10 5.00 4.5 4.25 3.75 4.5 20 17.00 10.00 18.50 8.00 6.5 7.25 30 23.00 14.75 12.00 11.00 9 9.75 Conclusion The results in Table 1 are shown graphically in Fig.1. Room temperature changed only slightly, so it will not have affected the results. From Fig 1 it is clear that the rate of heat loss from the water is reduced by increasing the amount of insulation. With no insulation the temperature fell by 23 à ¯Ã‚ ¿Ã‚ ½C in 30 minutes. With two layers this reduced to 14.75à ¯Ã‚ ¿Ã‚ ½C in 30 minutes. Figure 1 shows that by adding more and more layers of insulation the reduction in energy reduces to a point where it changes very little and may even increase. Figure 1 also shows that the rate of loss of heat is almost a straight line but there is a slight curve. This is most clearly seen from the curve with no insulation. This is because; as the water cools the temperature differential between the water and room temperature reduces so the energy loss will reduce. The curves for the insulation are straighter because the change in temperature differential is less. Table 2 compares the reduction in temperature at 10, 20 and 30 minutes for the various thicknesses of insulation. Fig. 2 shows that the reduction in temperature reduces with the number of layers to a low point at about 8 layers and it rises again a little for 10 layers. This is not what I expected in my prediction. This is because of radiation. Insulation can be used to prevent heat loss however it does not prevent heat loss by radiation. Heat which does get through the insulation will be radiated away. The amount of radiation will depend upon the temperature differential between the outside surface of the insulation and room temperature. As the insulation gets thicker less heat passes through and the outside temperature is lower so the amount of radiation should reduce. However, with a circular cup, the surface area of the insulation increases so the amount of radiation also increased and this may be what is stopping the reduction in heat loss. The surface area without insulation is approximately 250 cmà ¯Ã‚ ¿Ã‚ ½. The surface area with insulation is 620 cmà ¯Ã‚ ¿Ã‚ ½ which is 2.48 times as much. The experiment suggests that there is an optimum thickness for the insulation Evaluation Accuracy Figure 1 shows the curves for the temperature readings. Some of the points do not fit on the smooth best fit curve which could be drawn through the points. This shows that there was an error in the readings for those points. However, the errors are not sufficient to affect the overall conclusions. Table 3 shows the temperature steps between each reading and Fig 3 shows the irregularities for three of the tests. With this experiment it is not possible to retake or double check readings because the temperature keeps changing. If money were no expense, it would be better to use an automatic measuring system where a computer records the readings at the exact interval rather than allowing for human response. A digital thermometer would be used to record the temperature because it could readings of 0.1 of a degree rather than 0.25. From the results in Fig 1, I can see that the time at which the clock is started at 80à ¯Ã‚ ¿Ã‚ ½C is very critical because the temperature is only falling at about 1/2 a degree Celsius per minute. This could lead to an error of about 2 minutes. This could possibly explain the discrepancy between 8 and 10 layers. Further investigation I would like to investigate the effect of adding even more insulation to see if the rate of loss of energy increases due to the increase in surface area increasing the amount of radiation. I would do this because as you can see in Fig 2. The curve begins to slope up showing an increase in change of temperature. I would like to investigate this further and see if this trend continues with more layers of insulation. The experiment could also be repeated for different temperature ranges between the water and room temperature.

Funny Quotes About Women

Funny Quotes About Women Women are not easy to understand, at least according to the famous authors, poets,  entertainers, and comedians who have written on the nature of women. None of them claim to fully fathom the female mind. Find out what they really think of these  funny quotes about women - some written by men, some by women. Read wisecracks about a womans nature that make most women exclaim, Whats all the fuss about? But men say, How true, how true! Will Rogers There are two theories to arguing with a woman. Neither works. Robert Heinlein Women and cats will do as they please, and men and dogs should relax and get used to the idea. Nancy Reagan A woman is like a tea bag. She only knows her strength when put in hot water. Sigmund Freud Despite my thirty years of research into the woman soul, I have not yet been able to answer the great question that has never been answered: What does a woman want? Margaret Mead I do not believe in using women in  combat  because females are too fierce. Aristotle If women didnt exist, all the money in the world would have no meaning. James Thurber I hate women because they always know where things are. Malcolm de Chazal A woman knows how to keep quiet when she is in the right, whereas a man when he is in the right, will keep on talking. Freya Stark The great and almost only comfort about being a woman is that one can always pretend to be more stupid than one is and no one is surprised. Gloria Steinem Someone once asked me why women dont gamble as much as men do and I gave the commonsensical reply that we dont have as much money. That was a true but incomplete answer. In fact, womens total instinct for gambling is satisfied by marriage. Some of us are becoming the men we wanted to marry. Dave Barry Scientists now believe that the primary biological function of breasts is to make men stupid. Joseph Conrad Being a woman is a terribly difficult task since it consists principally in dealing with men. Ogden Nash I have an idea that the phrase weaker sex was coined by some woman to disarm some man she was preparing to overwhelm. Virginia Woolf For most of history, Anonymous was a woman. Charlotte Whitton Whatever women do they must do twice as well as men to be thought half as good. Luckily this is not difficult. Chris Rock There are only three things women need in life: food, water, and compliments. Mae West Good girls go to heaven. Bad girls go everywhere. Mike Vanatta Woman arent confusing. Theyre a Sudoku-Jenga puzzle surrounded by Rubiks cubes strapped to a terrorist screaming at you in another language. Ann Landers Women complain about sex more often than men. Their gripes fall into two major categories: (1) Not Enough. (2) Too Much. Harry Haenigsen Feminine intuition is a fiction and a fraud. It is nonsensical, illogical, emotional, ridiculous and practically foolproo..