Modern Chinese History Essay Example | Topics and Well Written Essays - 1750 words

Modern Chinese History - Essay Example According to him, self-strengthening programs that advocated for training led to the introduction of modern schools and arsenal. To achieve National and personal strength, he acknowledged that it does not only arise from the  physical effort  but also the will to acquire and preserve. He argued that a strong leadership and physical prowess merely depend on the will of the individuals to act heroically (Schell 205). These notions intertwined with Confucius teachings help to shape the beliefs and behavior of the nation. Although some individuals despised his concepts and ideas, he demonstrated, taught, and inspired Chinese through his writing through his publications. These writings were effective in cultivating moral standard inspired by truth. This resulted in the eruption of May Fourth Incident in 1919, where individuals demonstrated. A movement by the name May Fourth movement emerged with a collective desire to liberate China and cultivate a new Chinese culture (Schell 207). It targeted to change the political system of the country to make it flexible to accommodate further changes that may occur in the future. Although the movement did not have a clear objective, they opted to attract good governance even though it shall be through violent and harsh manner. The group appreciated the concepts that Mao taught in Chen Duxius, New Youth. According to the movement, direct violent among other political actions are fundamental ingredients for revolutionary action. After working for a longer time in the university library, Mao Zedong returned home in 1920 to form a study group. The group discussed Marxism and socialist  ideologies.Within the group, he emphasized the concept of Marxism especially the historical materialism that described history and dynamics of developing the  history.

A illustrated time line 1945 1997 Coursework Example | Topics and Well Written Essays - 250 words

A illustrated time line 1945 1997 - Coursework Example As a result, the coalition government ended as Labour leader Clement Attlee clearly won majority seats over Winston Churchill. In addition to this, the year also finished with celebration of the victory in the World War II. In 1948 National Health Service was established and Labour government made significant changes that promote medical services. Moreover, a free paid system was introduced to those who registered with a doctor. Labour Leader Clement Attlee was re-elected as Prime minister in 1950. Later British troop were sent to support the USA in the cold War at South Korea. In the year 1951, Winston Churchill won the general election under Conservative party and became the Prime Minister for the second time at the age of 76. He promoted foreign affairs, reduced pressure of Cold War and maintained good relationship with the USA. He once said that â€Å"We see nothing but good and hope in a richer, freer, more contented European commonalty. But we have our own dream and our own ta sk. We are with Europe, but not of it. We are linked, but not comprised. We are interested and associated, but not absorbed† (Britannica.com). After the death of George VI in 1952, his daughter Elizabeth II became the Queen and the Prime Minister supported her. In 1955 Winston Churchill at the age of 80 went on retirement due to the health issues. His successor was Anthony Eden who won the general elections in 1956. Furthermore, British power station was turned on for the first time. However, Egypt decided to nationalize the Suez Canal and American intervention made Britain and France to withdraw and Egypt got the canal back. As a result, it placed America higher over them. In the year 1957, The Prime Minister Sir Anthony Eden resigned due to Suez Crisis and was taken over by Harold Macmillan. Besides, Britain tested its first hydrogen bomb and joined to Soviet Union. The Conservatives leader Harold Macmillan won the general election with great margin of votes

Team Reflection Essay Example for Free

Team Reflection Essay Novelty products for retail sale Capital expenditure purchases of large equipment that are used for the business. Kitchen Equipment (Grill, Refrigeration, Dishwasher) Air Conditioning Unit Copy or Fax Machines Computers Weekly Topics Related to the Common Contracts This week we reviewed how the statute of frauds apply to common law Contracts that involve the sale of an interest of land Contracts that cannot be performed in under one year. Contracts to pay the debt of another (such as a loan surety) Contracts made in consideration of marriage (such as a prenuptial) We also discussed contract performance and the obligation of the parties to perform within the requirements or agreement of a contract. The parties agree on terms and perform the contractual obligations in good faith in order to complete the contract. Topics Comfortable With How the UCC Article 2 can be applied on a contract for the sale of goods between two merchants. Understanding the different types of contracts. Identifying the appropriate source of law for each contract type. The duty to mitigate, It was surprising to learn that the law imposes an obligation to take appropriate steps in order to avoid incurring damages and losses. As long as one can avoid the damages with reasonable effort, without undue risk or expense, they may not be able to sue the other party. Topics Struggled With Anticipatory Repudiation – how is the non-breaching party entitled to a remedy The IRAC method is still a topic most of us are still struggling with.

Introduction Of Melamine Milk History Essay

Introduction Of Melamine Milk History Essay In 2008, Chinese milk was a food safety incident in China involving milk, infant formula, other food materials and components added with melamine. Melamine is used to manufacture melamine-formaldehyde resin a type of plastic known for its flame retardant properties. They added melamine that has nitrogen-rich and is illegally added to food products to increase their apparent protein content. It has also been used as non-protein nitrogen in soy meal, corn gluten meal and cottonseed meal used in cattle feed. Melamine is known to cause renal and urinary problems in humans and animals when it reacts with cyanuric acid inside the body sometimes in drinking water and in animal feed. The Kjeldahl and Dumas test the protein levels fail to distinguish between nitrogen in melamine and naturally occurring in amino acids allowing the protein levels to be falsified. Introduced into milk, it can help conceal its fraudulent dilution with water. November 2008 China reported 300,000 victims, six infants dying from kidney stones and other kidney damage. The chemical appeared to have been added to milk in order to cause it to appear to have higher protein content. In a separate incident four years before, watered-down milk had resulted in 13 infant deaths from malnutrition. The scandal broke on 16 July, after sixteen infants in Gansu Province who had been fed on milk powder produced by Shijiazhuang-based Sanlu Group were diagnosed with kidney stones. After the initial focus on Sanlu market leader in the budget segment government inspections revealed the problem existed to a lesser degree in products from 21 other companies. The issue raised concerns about food safety and political corruption in mainland China, and damaged the reputation of Chinas food exports with at least 11 countries stopping all imports of mainland Chinese dairy products. A number of arrests occurred as a result of the scandal; the head of Sanlu, seven local government officials, as well as the Director of the Administration of Quality Supervision, Inspection and Quarantine (AQSIQ) were fired or forced to resign in response to the incident. In late October 2008, similar adulteration with melamine was discovered in eggs and possibly other food, traced to melamine being added to animal feed-despite a ban imposed in June 2007 following the scandal over pet food exported to the United States. As of July 2010, Chinese authorities were still reporting some seizures of melamine-contaminated dairy product in some provinces, though it was unclear whether these new contaminations constituted wholly new adulterations or were the result of illegal reuse of material from the 2008 adulterations Source of contamination The World Health Organization (WHO) said that melamine may be found in a variety of milk and milk products at varying levels, from low (part per billion) ppb to (part per million) ppm ranges. One academic suggests it may have been part of the food chain in China for a long time, as cyromazine (a melamine derivative) is a very commonly used poison in China. Cyromazine is absorbed into plants as melamine, and may therefore be present in the food chain, which includes poultry, eggs, fish, and dairy products. It is not known where in the supply chain the melamine was added to the milk. The chemical is not water-soluble and must be mixed with formaldehyde or another chemical before it can be dissolved in milk. Caijing reported that spiking fresh milk with additives such as melamine was no longer a secret to Hebei dairy farmers for the past two years. Caijing reported that the melamine in the tainted milk may have come from scrap melamine costing  ¥700 per tone less than one-tenths of the price of 99% pure industrial grade melamine. The melamine production process produces pure melamine by crystallization; the melamine remaining in the mother liquor is impure (70%) and unusable for plastics, so it is scrapped. It said that Sanlus baby formula melamine content was a result of tampering by adding low cost vegetable protein (such as low grade soya powder), and large amounts of scrap melamine as filler. Scrap melamine contains impurities such as cyanuric acid that form more insoluble crystals than melamine alone, aggravating the problem. Victims On 17 September 2008, Health Minister Chen Zhu stated that tainted milk formula had sickened more than 6,200 children, and that more than 1,300 others, mostly newborns, remain hospitalized with 158 suffering from acute kidney failure. By 23 September, about 54,000 children were reported to be sick and 4 had died. An additional 10,000 cases were reported from the provinces by 26 September. A World Health Organization official said 82 percent of the children made ill were 2 years of age or below. The Hong Kong Centre for Food Safety said that 99% of victims were aged less than 3 years. Ten of Hong Kong children were diagnosed with kidney problems at least four cases were detected in Macau and six in Taiwan. Non-human included a lion cub and two baby orangutans which had been fed Sanlu milk powder at Hangzhou Zoo. The government said on 8 October it would no longer issue updated figures because it is not an infectious disease, so its not absolutely necessary for us to announce it to the public. Compiled figures reported by local media across the country, and said the toll stood at nearly 94,000 at the end of September, excluding municipalities. Besides that, 13,459 children had been affected in Gansu, Reuters quoted Xinhua saying. Henan had reported over 30,000 cases, and Hebei also had nearly 16,000 cases. In late October, the government announced that health officials had surveyed 300,000 Beijing families with children of less than 3 years of age. It disclosed that approximately 74,000 families had a child who had been fed melamine-tainted milk, but did not reveal how many of those children had fallen ill as a result. Due to the many months before the scandal was exposed, media suggests that official figures are likely to be understated. Kidney stones in infants started being reported in several parts of China in the past two years. A number of yet to be officially acknowledged cases were reported on by the media. However, those deaths without an official verdict may be denied compensation. On 1 December, Xinhua reported that the Ministry of Health revised the number of victims to more than 290,000 and 51,900 hospitalized authorities acknowledged receiving reports of 11 suspected deaths from melamine contaminated milk powder from provinces, but officially confirmed 3 deaths On treatment of urinary stones in affected infants, the New England Journal of Medicine printed an editorial in March 2009, along with reports on cases from Beijing, Hong Kong and Taipei. Urinary calculi specimens were collected from 15 cases treated in Beijing and were analyzed as unknown objects for their components at Beijing Institute of Microchemistry using infrared spectroscopy, nuclear magnetic resonance, and high performance liquid chromatography. The result of the analysis showed that the calculus was composed of melamine and uric acid and the molecular ratio of uric acid to melamine was around 2:1. In a study published in 2010, researchers from Peking University studying ultrasound images of infants who fell ill in the 2008 contamination found that while most children in a rural Chinese area recovered, 12 per cent still showed kidney abnormalities six months later. The potential for long-term complications after exposure to melamine remains a serious concern, the report said. Our results suggest a need for further follow-up of affected children to evaluate the possible long-term impact on health, including renal function. Sanlu group The scandal began with revelations of contamination of Sanlu milk products. The New Zealand dairy cooperative Fonterra which owns a 43% stake in Sanlu, said they were alerted to melamine contamination on 2 August (almost a month before the issue became public), and have said to have pushed hard for a full public recall. Although there was an immediate trade recall, Fonterra said that local administrators refused an official recall Apologize On 15 September, the company issued a public apology for the contaminated milk powder. Sanlu was ordered to halt production, and to destroy all unsold and recalled products. Authorities reportedly seized 2,176 tons of milk powder in Sanlus warehouses. An estimated 9,000 tons of product had been recalled. Tian Wenhua, Chairwoman and General Manager of Sanlu and Secretary of the Sanlu Communist Party chapter was stripped of her party and functional posts during an extraordinary meeting of the Hebei provincial standing committee of the four Shijiazhuang officials, including vice mayor in charge of food and agriculture, Zhang Fawang, were reportedly removed from office. Shijiazhuang Mayor Ji Chuntang resigned on 17 September. Li Changjiang minister in charge of the AQSIQ was forced to resign on 22 September after the State Council inquest concluded that he was responsible for the negligence in supervision. Investigators also blamed the Shijiazhuang government. Local Party Secretary Wu Xi anguo was fired on the same day. Arrests Sanlu GM Tian was charged under Articles 144 and 150 of the criminal code. A spokesman for the Hebei Provincial Public Security Department said police had arrested 12 milk dealers and suppliers who allegedly sold contaminated milk to Sanlu, and six people were charged with selling melamine. 300  kg of suspicious chemicals, including 223  kg of melamine, were confiscated. Among those arrested were two brothers who ran a milk collection centre in Hebei for allegedly supplying three tones of adulterated milk daily to the dairy the owner of another collection centre which resold seven tons of milk a day to Sanlu, was arrested, and his operation was shut down. Zhang Yujun (alias Zhang Haitao), a former dairy farmer from Hebei, produced more than 600 tons of a protein powder mixture of melamine and maltodextrin from September 2007 to August 2008. He and eight other traders, cattle farm owners and milk purchasers who bought the powder from him were arrested in early October, bringing the total to 36. During the week of 22 December 2008, 17 people involved in producing, selling, buying and adding melamine in raw milk went on trial. Tian Wenhua, former Sanlu general manager and three other company executives appeared in court in Shijiazhuang, charged with producing and selling milk contaminated with melamine. According to Xinhua, Tian pleaded guilty, and told the court she learned about the tainted milk complaints from consumers in mid-May. She then apparently headed a working team to handle the case, but did not report to the Shijiazhuang city government until 2 August. The Intermediate Peoples Court in Shijiazhuang sentenced Zhang Yujun and Geng Jinping to death, Tian Wenhua to life in prison, on 22 January 2009. Zhang was convicted for producing 800 tons of the contaminated powder, Geng for producing and selling toxic food. The China Daily reported Geng had knelt on the courtroom floor and begged the victims families for forgiveness during the trial. The court also sentenced Sanlu deputy general managers Wang Yuliang and Hang Zhiqi to fifteen years and eight years in jail respectively, former manager Wu Jusheng to five years. Several defendants have appealed. Zhang Yujun and Geng Jinping were executed on 24 November 2009. Effect on the company The value of the company plunged as a result of the scandal. On 24 September, Fonterra announced that it had written down the carrying value of its investment by NZ$139  million (two-thirds), reflecting the costs of product recall and the impairment of the Sanlu brand because of the criminal contamination of milk. By 27 September, China Daily reported that Sanlu was close to bankruptcy, and might be taken over by the Beijing Sanyuan Foods Company. The company is also facing lawsuits from parents. The Beijing Review said that Sanlu expects to have to pay compensation claims totaling 700  million, and it became clear that the company would be broken up and sold. On 25 December, Shijiazhuang court accepted a creditors bankruptcy petition against Sanlu. Media commentators expected the Sanlu distribution network to be sold. Trade and industry impact for Chinese industry The State Council ordered the testing of product of all dairy producers, and to this end, some 5,000 inspectors were dispatched. The mainland Chinese market has grown at an average annual rate of 23% since 2000. In 2006, milk production reached 30  million tons, ten times the volume of a decade before. It was valued at some  ¥122  billion (US$18  billion) in 2007, and consumers have severely lost confidence in the industry. The events have exposed the often incestuous relationship between local business and local government. In addition to the tax revenues to local authorities Sanlu contributed  ¥330  million in 2007, many companies invite local officials to become silent partners in their corporations in return for protection at the political level; former Sanlu chairman Tian Wenhua, was made honorary deputy to the Provincial Peoples Congress. The scandal has also highlighted structural problems of inadequate production volume, inherent quality issues, and poor production methods. The Inner Mongolia region produces over one-fourth of Chinas milk and Mengniu and Yili have invested millions to establish state-of-the-art dairy facilities in its capital, Hohhot the companies still rely on small-scale farmers for over 90% of their production because of the capacity constraint of the modern facilities. Both companies were said by farmers and agents to have habitually purchased milk which failed quality tests, for only two-thirds the normal price. A new policy was put in place on 17 September to stop that practice. Foreign operations in China Mengniu-Arla, joint-venture between Danish/Swedish co-operative Arla Foods and Mengniu halted production on 16 September 2008 after three out of 28 tests taken from Mengniu showed traces of melamine; contaminated batches had been recalled.Mengniu, milk supplier to Starbucks was replaced by Vitasoy when the coffee retailer eschewed milk in favor of soya milk in its China operations. KFC also suspended selling Mengniu milk. Tokyo-headquartered Lotte Group a major snacks maker, recalled its Koalas March cookies in Hong Kong and Macau because of contamination, and promised to look deeply into all the details of the manufacturing process in order to preserve customer confidence. The range was also ordered off Dutch and Slovakian shelves. Its Chocolate Pie was seized when samples tested positive in Malta. On 29 September, British confectionery group Cadbury withdrew all of its 11 chocolate products made in its three Beijing factories, on suspicion of melamine contamination. The recall affected the mainland China markets, Taiwan, Hong Kong and Australia. Tests in Hong Kong found excessive amounts of melamine in China-made Dairy Milk products. On 30 September, Unilever recalled its Lipton milk tea powder after the companys internal checks found traces of melamine in the Chinese milk powder used as an ingredient Heinz recalled cases of baby cereal in Hong Kong after discovering they contained melamine. Nestlà ©s factory in Heilongjiang was also implicated: the Taiwanese Department of Health forced the delisting of six Neslac and KLIM products on 2 October for containing minute traces of melamine, although the minister said they did not pose a significant health risk. Since the milk crisis broke, Nestlà © says it has sent 20 specialists from Switzerland to 5 of its Chinese plants to strengthen chemical testing. On 31 October, it announced the opening of a $10.2  million Beijing research and development centre, to serve as the base and the reference in food safety for Nestlà © in Greater China. Nestlà © Chief Technology Officer said that the centre was equipped with highly sophisticated analytical tools for detecting trace amounts of residues and undesirable compounds like melamine or veterinary drugs or natural toxins http://en.wikipedia.org/wiki/2008_Chinese_milk_scandal EFFECT ON INTERNATIONAL TRADE ADVANTAGES: No problem of dead baby. No problem of infant breast. DISADVANTAGES: Loss job. Increase in countrys income. Relationship between local business and local government. Ruin relationship with other country. CONCLUSION The foods that have melamine content bring bad impact not only to the customers who are using the product but to the producer. It also gives impact to the China industry. It also makes consumer loss confident to the industry. RECOMMENDATION Government must test the product before market it. Government must take action to the people who make poison product. The organization should run their business with honestly and do not take advantages. Customer should careful before their buy the product.

Microcontroller Based DC Motor Speed Controller

Microcontroller Based DC Motor Speed Controller In this report I present a microcontroller based DC motor speed controller. DC motors play a vital role in most of the industrial areas. They are mainly used for the mechanical movements of physical applications such as media drives, power plants, lifts, elevators, conveyers, belt driven loads (printing press) etc. The controller implements the control strategy governing the load and motor characteristics. To match the load and motor, the input to the microcontroller is manipulated by the controller. The purpose of a motor speed controller is to capture a signal representing the demanded speed, and to drive the motor at that speed. The controller may or may not actually measure the speed of the motor. If it does, it is called a Feedback Speed Controller or Closed Loop Speed Controller, if not it is called an Open Loop Speed Controller. Feedback speed control is better, but more complicated, and may not be required for a simple circuit design. The former (closed loop) is implemented in the presented controller design. The subject arrangement consisted of a tachometer attached to the shaft of the motor. A controller design cannot be more accurate than methods aimed at measuring actual motor speed. This is readily attained by coupling the motor shaft with a tachometer. The tachometer output signal is converted to a dc voltage signal acceptable to the microcontroller. The microcontroller is programmed to drive the motor accomplishing the load requirement. The operation of dc motor was studied. Several types of motors and various control types were investigated. The project also intends to familiarize us with the efficiency of PIC in control systems. To evaluate the effectiveness of the controller, analysis will be conducted driving variable load while maintaining constant speed of the motor. The advantages of using microcontrollers to control dc motor were studied. INTRODUCTION 1.1 MOTOR An electric motor is an electromechanical device that converts electrical energy to mechanical energy. The mechanical energy can be used to perform work such as rotating a pump impeller, fan, blower, driving a compressor, lifting materials etc. It is estimated that about 70% of the total electrical load is accounted by motors only. 1.2 CLASSIFICATION OF MOTORS Electric Motors Alternating Current (AC) Motors Direct Current (DC) Motors Synchronous Induction Three-Phase Single-Phase Self Excited Separately Excited Series Shunt Compound FIG-1.1 classification of motors 1.3 AC MOTORS An AC motor is a motor that is driven by an alternating current. It consists of two basic parts, an outside stationary stator having coils supplied with alternating current to produce a rotating magnetic field, and an inside rotor attached to the output shaft that is given a torque by the rotating field. 1.3.1 TYPES OF AC MOTORS There are two types of AC motors, depending on the type of rotor used. The first is the synchronous motor, which rotates exactly at the supply frequency or a sub multiple of the supply frequency. The magnetic field on the rotor is either generated by current delivered through slip rings or by a permanent magnet. The second type is the induction motor, which turns slightly slower than the supply frequency. The magnetic field on the rotor of this motor is created by an induced current. 1.3.2 TYPES OF INDUCTION MOTORS Squirrel-Cage Induction Motors The most simple and reliable of all electric motors. It is essentially a constant speed machine, which is adaptable for users under all but the most severe starting conditions. Requires little attention as there are no commutator or slip rings, yet operates with good efficiency. Wound-Rotor (Slip Ring) Induction motor It is used for constant speed-service requiring a heavier starting torque than is obtainable with squirrel cage type. Because of its lower starting current, this type is frequently used instead of the squirrel-cage type in larger sizes. These motors are also used for varying-speed-service. Speed varies with this load, so that they should not be used where constant speed at each adjustment is required, as for machine tools. Single Phase Induction Motors This motor is used mostly in small sizes, where polyphase current is not available. Characteristics are not as good as the polyphase motor and for size larger than 10 HP, the line disturbance is likely to be objectionable. These motors are commonly used for light starting and for running loads up to 1/3 HP Capacitor and repulsion types provide greater torque and are built in sizes up to 10 HP. Synchronous Motors Run at constant speed fixed by frequency of the system. Require direct current for excitation and have low starting torque. For large motor-generators sets, frequency changes, air compressors and similar apparatus which permits starting under a light load, for which they are generally used. These motors are used with considerable advantage, particularly on large power systems, because of their inherent ability to improve the power factor of the system. 1.4 DC MOTOR Direct-Current motors, as the name implies, use a direct-unidirectional current. A DC motor has three main components: Field pole. The interaction of two magnetic fields causes the rotation in a DC motor. The DC motor has field poles that are stationary and an armature that turns on bearings in the space between the field poles. A simple DC motor has two field poles: a north pole and a south pole. The magnetic lines of force extend across the opening between the poles from north to south. Armature. When current goes through the armature, it becomes an electromagnet. The armature, cylindrical in shape, is linked to a drive shaft in order to drive the load. The armature rotates in the magnetic field established by the poles, until the north and south poles of the magnets change location with respect to the armature. Once this happens, the current is reversed to switch the south and north poles of the armature. Commutator. This component is found mainly in DC motors. Its purpose is to overturn the direction of the electric current in the armature. The commutator also helps in the transmission of current between the armature and the power source. 1.4.1 OPERATION OF A DC MOTOR: When a dc motor is subject to dc voltage, the current flows through the armature coil. A wire carrying current also has a magnetic field around it. This magnetic field distorts the parallel magnetic field of stator to produce a force which causes the armature coil to turn. FIG-1.2 operation of motor Each coil of the armature is not only connected to the brushes but the brushes are connected first to one end and then to the other end of the coil. This commutating action is necessary to maintain the same direction of the current flow in the armature coils relative to the magnetic field lines in the field poles. The motor would never turn without commutation. FIG-1.3 cross section diagram of a motor 1.4.2 Types of Excitations There are two basic elements in a DC motor. The way in which these are connected results in various types of DC motors. SHUNT WOUND: The construction and principle of operation of a shunt motor is similar to any DC motor. This type of motor is called shunt because the field is in parallel or shunts the armature. The shunt field is directly connected in parallel with the armature circuit. Shunt windings require large number of turns to produce a strong magnetic field. SERIES WOUND: In a series wound motor, the field is connected in series with the armature. In this type, the speed tends to increase until the back EMF equals the impressed voltage. The EMF also decreases the current in the field and armature. As the field weakens more speed is required to maintain the counter EMF. Thus a series motor is used only where the load is attached e.g. A lift truck, an electric crane. Etc. COMPOUND WOUND: A compound motor has two field windings, the shunt field and series field. The shunt connected in parallel with the armature and the series field connected in series with the armature. The combination of both fields gives double advantages. It has a greater torque than the shunt motor due to the series field and fairly constant speed due to the series field winding. The compound motor has both shunt and series motor characteristics. These will be discussed along with their control techniques in the next chapter. 1.5 TACHOMETER A tachometer is an instrument that measures the rotational speed of the shaft of the motor. It functions in a similar fashion as compared to a speedometer on a car. It tells you the speed of the car. Similarly the tachometer is used to measure the motor speed. In a closed loop control system the information about the instantaneous state of the output is fed back and compared with the input and difference is used to modify the output in such manner as to achieve a desired condition. Similarly a tachometer is coupled to the shaft of the motor. Thus a signal representing the speed of the motor is produced. This signal is fed back to the input where it is compared to the speed command voltage. The error produced is actuated by the speed of the motor. In my designed controller the error actuating and motor control is achieved by programming the microcontroller. It is used to control the rotation of the motor. It senses the input and process it using the program burned in it and gives the required PWM output on the required port pins. This output controls the on/off time of the mosfet and thus controls the motor. This technique and mosfets will be discussed in the next chapter. As long as the speed command voltage is held constant, the motor will run at a proportional constant speed regardless of the mechanical load. The set speed control gives a dc voltage input, for example 12 volts for maximum speed and zero for stationary. This could be a potentiometer providing any voltage in a range from zero to +12 volts. The microcontroller (PIC) amplifies the difference between the two input voltages (tachometer and potentiometer) and the error is actuated. 1.6 MICROCONTROLLER (PIC) The name PIC initially referred to Programmable Interface Controller. Advantages of using PIC over other controlling devices for controlling the DC motor are given below: SPEED The execution of an instruction in PIC IC is very fast (in micro seconds) and can be changed by changing the oscillator frequency. One instruction generally takes 0.2 microseconds. COMPACT: The PIC IC will make the hardware circuitry compact. RISC PROCESSOR The instruction set consists of only 35 instructions. EPROM PROGRAM MEMORY Program can be modified and rewritten very easily. INBUILT HARDWARE SUPPORT Since PIC IC has inbuilt programmable timers, ports and interrupts, no extra hardware is needed. POWERFUL OUTPUT PIN CONTROL Output pins can be driven to high state, using a single instruction. The output pin can drive a load up to 25mA. INBUILT I/O PORTS EXPANSIONS This reduces the extra ICs which are needed for port expansion and port can be expanded very easily. INTEGRATION OF OPERATIONAL FEATURES Power on reset and brown/out protection ensures that the chip operates only when the supply voltage is within specification. A watchdog timer resets PIC if the chip ever malfunctions and deviates from its normal operation. The speed of motor is directly proportional to the DC voltage applied across its terminals. Hence, if we control the voltage applied across its terminal we actually control its speed. A PWM (Pulse Width Modulation) wave can be used to control the speed of the motor. Here the average voltage given or the average current flowing through the motor will change depending on the ON and OFF time of the pulses controlling the speed of the motor i.e. The duty cycle of the wave controls motor speed. This wave is generated by the PIC. . CHAPTER 2. 2.1 DC SHUNT MOTOR FIG -2.3 Shunt windings require large number of turns to produce a strong magnetic field. This is because a small gauge wire cannot handle heavy currents. As a result, when voltage is applied, very little current flows through the shunt coil. The interaction of the magnetic fields between the one from armature and the one from shunt coil causes the motor to rotate. The speed can be controlled by varying the field strength or armature voltage. Current is supplied from the stationary housing to the rotating armature through commutator brushes arrangement. As the stator is stationary, power is applied directly to it. 2.1.2 SPEED CONTROL OF A DC SHUNT MOTOR This type of motor runs at a constant speed practically, regardless of the load. It is the type generally used in commercial practice. Speed of the shunt wound motors may be varied in two ways: First, by inserting resistance in series with the armature, thus decreasing speed (FIG ) And second, by inserting resistance in the field circuit. In this case the speed will vary with each change in load. This normally works with any controller setting i.e. it maintains constant speed despite variable load. Therefore, a shunt motor has proved its efficiency in adjustable speed service and loads requiring a low starting torque. 2.2 DC SERIES MOTOR In a series motor, the field winding (shunt field) is connected in series with the armature winding (A) as shown in the figure. The field current is therefore equal to the armature current. Speed is restricted to 5000 RPM It must be avoided to run a series motor with no load because the motor will accelerate uncontrollably. FIG-2.5 V = Supply voltage E = Generated e.m.f I = Supply current RA = Armature resistance RF = Field resistance 2.2.2 SPEED CONTROL OF A DC SERIES MOTOR The speed of a series motor depends almost entirely on the flux. The stronger the field flux, the lower the speed. Likewise, decrease in load current and therefore in field current and field flux causes an increase in speed. This can be achieved by adding a resistor in parallel with the series field winding. This causes the field current to decrease and the flux drops accordingly. This causes the motor speed to increase. The speed can be decreased by adding an external resistor in series with the armature and the field winding. This would cause a reduction in the armature supply voltage causing the motor speed to decrease. 2.3 DC COMPOUND MOTOR A DC compound motor is a combination of shunt and series motor. In a compound motor, the field winding (shunt field) is connected in parallel in series with the armature winding (A). For this reason this motor has a good starting torque and a stable speed. The higher the percentage of compounding (i.e. percentage of field winding connected in series), the higher the starting torque this motor can handle. For example, compounding of 40-50% makes the motor suitable for hoists and cranes, but standard compound motors (12%) are not. There are 2 major types of compound motors. These are given below: Cumulative compound motors Differential compound motors FIF-2.6 CUMULATIVE COMPOUND MOTOR FIG-2.7 DIFFERENTIAL COMPOUND MOTOR 2.3.2 SPEED CONTROL OF A COMPOUND MOTOR The speed of a compound motor can easily be controlled by changing the voltage supply to the motor. A solid state AC variable frequency motor drive can also be used to vary the speed of an AC motor. 2.4 PWM (PULSE WIDTH MODULATION) PWM, or Pulse Width Modulation, is a method of controlling the amount of power to a load without having to dissipate any power in the load driver. Imagine a 10W light bulb load supplied from a battery. In this case the battery supplies 10W of power, and the light bulb converts this 10W into light and heat. No power is lost anywhere else in the circuit. If we wanted to dim the light bulb, so it only absorbed 5W of power, we could place a resistor in series which absorbed 5W and then the light bulb could absorb the other 5W. This would work, but the power dissipated in the resistor not only makes it get very hot, but is wasted. The battery is still supplying 10W. An alternative way is to switch the light bulb on and off very quickly so that it is only on for half of the time. Then the average power taken by the light bulb is still only 5W, and the average power supplied by the battery is only supplying 5W also. If we wanted the bulb to take 6W, we could leave the switch on for a little longer than the time it was off, then a little more average power will be delivered to the bulb. This on-off switching is called PWM. The amount of power delivered to the load is proportional to the percentage of time that the load is switched on. Pulse-width modulation (PWM) or duty cycle variations are commonly used in speed control of dc motor. The duty cycle is defined as the percentage of digital high to digital low and digital high pulse-width during a PWM period. Thus by varying the pulse width, we can vary the average voltage across a DC motor and hence its speed In my presented controller design the PWM (Pulse Width Modulation) function of PIC is used for the electric current control to drive a motor. PWM can change the duty of the pulse to output into CCP1 by the data. The duty of the pulse of CCP1 is controlled in the voltage (the control voltage). When the control voltage is higher than the regulation value, the H level time of the CCP1 pulse is made long and the number of rotations of the motor is lowered. When the control voltage is lower than the regulation value, the H level time of the CCP1 pulse is made short and the number of rotations of the motor is raised. This mechanism will be discussed and elaborated in the next chapter. 2.5 MOSFETS The speed controller works by varying the average voltage sent to the motor. Imagine a light bulb with a switch. When you close the switch, the bulb goes on and is at full brightness, say 100 Watts. When you open the switch it goes off (0 Watts). Now if you close the switch for a fraction of a second, and then open it for the same amount of time, the filament wont have time to cool down and heat up, and you will just get an average glow of 50 Watts. This is how lamp dimmers work, and the same principle is used by speed controllers to drive a motor. When the switch is closed, the motor sees 12 Volts, and when it is open it sees 0 Volts. If the switch is open for the same amount of time as it is closed, the motor will see an average of 6 Volts, and will run more slowly accordingly. As the amount of time that the voltage is on increases compared with the amount of time that it is off, the average speed of the motor increases. This on-off switching is performed by power MOSFETs. A MOSFET (Metal-Oxide-Semiconductor Field Effect Transistor) is a device that can turn very large currents on and off under the control of a low signal level voltage 2.5.1 TYPES OF MOSFETS. There are NPN type and PNP type as the semiconductor part. When no voltage is applied no electric current flows between the drain and the source. NPN type is called N-channel and PNP type is called P channel. An oxide film is put to the semiconductor of NPN or PNP and metal is put onto it as the gate. In case of NPN, the part of N is a source pole and a drain pole. In case of PNP, the part of P is the polar side. When positive voltage is applied to the gate of the N-channel MOS FET, the electrons of N-channel of source and drain are attracted to the gate and go into the P-channel semiconductor among both. With the movement of these electrons, it conditions itself like spans a bridge for electrons between drain and source. The size of this bridge is controlled by the voltage to apply to the gate. . This type (N CHANNEL) of mosfet is used in the presented controller. FIG 2.8 In case of P-channel MOS FET, the voltage is opposite but does similar operation. When negative voltage is applied to the gate of P-channel MOS FET, the holes of P-channel of source and drain are attracted to the gate and go into the N-channel semiconductor among both. With the movement of these holes, a bridge for holes is spanned and the electric current flows between drain and source. Transistor controls an output current by the input current. However, in case of FET, it controls an output current by input voltage (Electric field). The input current doesnt flow. To handle a MOS FET, needs attention because the oxidation insulation film is thin. This film is prone to the high voltage of the static electricity and so on. CHAPTER 3 The highlighted part in the figure represents the shaft which links the motor and the tachometer. The speed of the motor is directly proportional to the frequency of the tachometer. The dc voltage input is provided by the potentiometer. The microcontroller operates on a dc voltage. The output from the tachometer is a sine wave which has to be rectified in order to operate the pic. This is achieved using an F/V converter. The converter releases a dc logic signal which operates the pic. CIRCUIT EXPLANATION: The input voltage to the main motor is controlled by a potentiometer. This variable resistor could be adjusted manually to provide a 0-12 v input. This voltage sets the number of rotations of the main motor. The input voltage of PIC becomes low when bringing VR1 close to the side 1 and PIC increases the drive electric current of the motor. That is, the revolution of the motor rises. The input voltage of PIC becomes high when bringing VR1 close to the side 3 and PIC reduces the drive electric current of the motor. That is, the revolution of the motor slows down. Control voltage is defined as the feedback signal which is produced to rectify the error between the desired and controlled speed. This is provided by the tachometer in our case. The output from the tachometer is a sine wave which cannot operate the microcontroller to perform the programmed functions. This is converted to a dc voltage signal compatible with the pic microcontroller. This changed voltage is used to enable the CCP feature of the PIC resulting in motor drive. The CCP feature will be discussed in detail later in the chapter. The control voltage to PIC is thus governed by the fluctuations of the main motor. This control voltage (feedback signal) is directly proportional to the rotational speed of the motor. The PIC microcontroller is the brain of the circuit controlling all actions to be done and the output. PIC controls the electric drive current for the control voltage to become a regulation value. When the revolution of the motor slows down, i.e. control voltage goes down, the drive electric current of the motor is increased and number of rotations is raised. When the control voltage reaches a regulation value, a drive electric current at the point is held. When the number of rotations of the motor is high, i.e. the control voltage is high, the drive electric current of the motor is reduced and number of rotations is lowered D1 is used to protect PIC when the voltage of the detection motor is high. The voltage which is applied to the terminal of PIC is a maximum of +5V. This zener diode prevents the destruction of PIC when the speed detection voltage of the motor exceeds 5V. CCP FEATURE Capture, Compare and Pulse Width Modulation feature is abbreviated to form CCP. Capture This is the function to capture the 16 bits value of timer1 register when an event occurs on pin RC2/CCP1. This can be used for the measurement of the period time of the signal like the frequency counter and so on Compare Generate an interrupt, or change on output pin, when Timer 1 matches a pre-set comparison value PWM Create a re-configurable steady duty cycle square wave output at a user set frequency. The timer resource of the capture and compare is timer1 and the timer resource of PWM is timer2. The following steps should be taken when configuring the CCP module for PWM operation: Set the PWM period by writing to the PR2 register. PWM Period equals [(PR2+1)]*4Tosc*(timer 2 prescale value), and the resultant PWM frequency equals 1/ PWM_Period. Tosc stands for time period of the oscillations. Set the PWM duty cycle by writing to the CCPR1L register and CCP1X and CCP1Y bits of CCP1CON register. Duty Cycle is based on CCPRxL, most significant byte, and CCPxCON, least significant two bits. CCPRxL functions as a comparative value with timer 2 and a scaling factor to determine the number of counts of CCPx. PWM logic remains high, without considering CCPxCON. The two least significant bits, CCPxCON, determine the percentage of the maximum resolution the PWM duty cycle is extended. Make the CCP1 pin an output by clearing the TRISC. Set the TMR2 prescale value and enable Timer2 by writing to T2CON register. Configure the CCP1 module for PWM operation. PWM can change the duty of the pulse to output into CCP1 by the data. When the time period of the H level of the pulse of CCP1 is short, the time of ON (the L level) becomes long in TR2 which implies that the drive electric current of the motor increases. Oppositely, when the H level time of the pulse of CCP1 is long, the ON time of TR2 becomes short and the drive electric current of the motor decreases. The duty of the pulse of CCP1 is controlled by the control voltage (feedback signal) which was taken in with input circuit. When the control voltage is higher than the regulation value, the H level time of the CCP1 pulse is made long and the number of rotations of the motor is lowered. When the control voltage is lower than the regulation value, the H level time of the CCP1 pulse is made short and the number of rotations of the motor is raised. A three terminal regulator is used for getting the operate voltage for pic. PARTS PIC16F873 3 Terminal regulator ( 7805) Transistor for MOS FET drive ( 2SC1815 ) Power MOS FET ( 2SK3142 ) Zener diode ( RD5A ) IC socket Resonator Variable resistor for motor speed setting Resistors Capacitors Printed board VFC 320 (F/V CONV) Bipolar transistor 2N222 FURURE WORK: Dec: complete circuit design and order components. January: software design and circuit assembly February: Simulation and preparation of final report and presentation March: review and appendices April: submission.

Earthquakes :: essays research papers

Earthquakes Earthquakes occur almost everyday all over the world. Most of the time earthquakes are not strong enough to be felt by people, but the shaking caused by an earthquake can be recorded by a seismometer. These machines are located all over the world to ensure detection of earthquakes of all strengths. Only occasionally will a larger magnitude earthquake strike and cause damage to the region. There are many faults around the world and depending on where these faults are plays a major factor in determining where an earthquake will occur. It is these faults that are the reason for earthquakes. The information seismologists know about past earthquakes and earthquakes in general give them a limited ability to generally predict when and where earthquakes are going to occur. An earthquake is the shaking of Earth’s surface caused by rapid movement of the earth’s rocky outer layer. â€Å"Earthquakes occur when tension stored in rocks suddenly releases† (Vogt 12). Faults occur at these places where rocks on either side of the crack have moved. Oceans are very common places for major tectonic plates to shift. When two plates separate, new oceanic crust is made near the fault as magma rises and eventually sets on the sea floor. If the plates on either side of the fault continue to spread then the ocean slowly becomes larger in width. This is called seafloor spreading. Mid-ocean ridges are characterized by a crack like valley at the fault. This crack like valley is caused by the tension pulling the plates apart, causing normal faulting to occur a number of times in the divergent boundary.   Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚   Shevchik 2 The most common type of fault is a normal or dip-slip fault. These occur when two blocks of earth are thrust toward each other, causing one to ride up over the other (Britt 1). â€Å"The hanging wall moves downward relative to the footwall† (Tarbuck 244). A reverse fault is the opposite of a normal fault. â€Å"The hanging wall moves upward relative to the footwall† (Tarbuck 244). A very powerful type of fault is the strike-slip fault that occurs when two plates slide past one another. The San Andreas Fault in California is a very good example of this type of fault. A great deal of damage is done when any type of fault shakes the soil under structures in a low-lying, waterlogged areas, causing liquefaction. Liquefaction occurs when an earthquake shakes the wet, sandy soil near a body of water.

Gothic Culture Essay -- Goths Renaissance History Essays

Gothic Culture You're walking down the street and all of a sudden you encounter a group of oddly dressed youngsters all in black, or perhaps wearing elaborate lace and brocade, looking strangely like they came out of eighteenth century. You immediately feel a bit of apprehensions as you clutch your child closer to and wonder what exactly it is that these kids are up to. Are they part of a Satan worshiping cult, or just a band of traveling actors? In either case their strange dress and pale likenesses took you aback and made you a bit prone to prejudge. What you were probably looking at were a group of Goths. What exactly is a Goth you may ask, and why the weird dress and affinity for black. This along with the origins, and some of the trials and tribulations faced by this extraordinary group of individuals, along with dispelling some common misconceptions is the objective of my writings. First lets take a look at what Goth is and where it began. Gage Canadian Dictionary defines "Goth." as "an uncivilized person, barbarian."( 1975:425) the origin of the word dates back to the third or fourth centuries when a Germanic tribe called the VisiGoths overran the Roman Empire and settled in what is now Sweden and the surrounding area (Shultz,1984:325). The word gained its modern meaning during the Italian Renaissance when the word was used to describe the architecture that was emerging at the time. The architecture was considered barbaric because of its pointed arches and steep roofs, along with the frequent use of the gargoyle, which was thought to ward of evil spirits. The modern Gothic movement and its origins are not as easily defined, and varies according to your source. I've combined the two to show an evolution of how it all... ...nformation has always been the key to help ease prejudices and discrimination, by introducing the ideology behind the Goth culture and explaining the reason behind the dress; I hope that it has brought about a better understanding of these people and their plight to a peaceful existence. Bibliography Fulton, Ben "Goths For Goodwill."City Beat (1998): 2p. Online. Internet. June 4,1998. www.slweekly.com/news/citybeat/cb 980604 a.html "Dictionary of Goth" 6/24/98 http:www.jesus.cam.ac.uk/~vkc20/goth/qzhtml Shultz, James.(1975) Germanic Tribes (3rd ED), Published by Weber and Van Syckle: Berlin Sangange, Eretica "Darkness Can be Felt"(1999): Online.Internet. June 30, 1999. http://pages.prodigy.com/Fifth Dream/goth.htm Yvain, Euphrosyne "Origins of Modern Gothic Culture"(1999) Online. Internet June 24,1999. http:www.blood-dance.net/goth/origins.html