Outsiders Summary Essays - Italian Politicians, Niccol Machiavelli

Outsiders Summary Annonymous In The Prince Niccolo Machiavelli presents a view of governing a state that is drastically different from that of humanists of his time. Machiavelli believes the ruling Prince should be the sole authority determining every aspect of the state and put in effect a policy which would serve his best interests. These interests were gaining, maintaining, and expanding his political power.1 His understanding of human nature was a complete contradiction of what humanists believed and taught. Machiavelli strongly promoted a secular society and felt morality was not necessary but in fact stood in the way of an effectively governed principality.2 Though in come cases Machiavelli's suggestions seem harsh and immoral one must remember that these views were derived out of concern Italy's unstable political condition.3 Though humanists of Machiavelli's time believed that an individual had much to offer to the well being of the state, Machiavelli was quick to mock human nature. Humanists believed that An individual only'grows to maturity- both intellectually and morally- through participation' in the life of the state.4 Machiavelli generally distrusted citizens, stating that ...in time of adversity, when the state is in need of it's citizens there are few to be found.5 Machiavelli further goes on to question the loyalty of the citizens and advises the Prince that ...because men a wretched creatures who would not keep their word to you, you need keep your word to them.6 However, Machiavelli did not feel that a Prince should mistreat the citizens. This suggestion once again to serve the Prince's best interests. If a prince can not be both feared and loved, Machiavelli suggests, it would be better for him to be feared bey the citizens within his own principality. He makes the generalization that men are, ...ungrateful, fickle, liars, and deceivers, they shun danger and are greedy for profit; while you treat them well they are yours.7 He characterizes men as being self centered and not willing to act in the best interest of the state,[and when the prince] is in danger they turn against [him].8 Machiavelli reinforces the prince's need to be feared by stating: Men worry less about doing an injury to one who makes himself loved than to one who makes himself feared. The bond of love is one which men, wretched creatures they are, break when it is to their advantage to do so; but fear is strengthened by a dread of punishment which is always effective.9 In order to win honor, Machaivelli suggests that a prince must be readily willing to deceive the citizens. One way is to ...show his esteem for talent actively encouraging the able and honouring those who excel in their professions...so that they can go peaceably about their business.10 By encouraging citizens to excel at their professions he would also be encouraging them to ...increase the prosperity of the their state.11 These measures, though carried out in deception, would bring the prince honor and trust amongst the citizens, especially those who were in the best positions to oppose him. Machiavelli postulates that a prince must also deceive those who attempt to flatter him. [In] choosing wise men for his government and allowing those the freedom to speak the truth to him, and then only concerning matters on which he asks their opinion, and nothing else. But he should also question them toughly and listen to what they say; then he should make up his own mind.12 Since each person will only advice the prince in accord to his own interests, the prince must act on his own accord. Machiavelli discourages action to taken otherwise ...since men will always do badly by [the prince] unless they are forced to be virtuous.13 Machiavelli actively promoted a secular form of politics. He laid aside the Medieval conception of the state as a necessary creation for humankinds spiritual, material, and social well-being.14 In such a state,[a] ruler was justified in his exercise of political power only if it contributed to the common good of the people he served, [and] the ethical side of a princes activity...ought to [be] based on Christian moral principles....15 Machiavelli believed a secular form of government to be a more realistic type. His views were to the benefit of the prince, in helping him maintain power rather than to serve to the well being of the citizens. Machiavelli promoted his belief by stating: The fact is that a man who wants to act virtuously in every way necessarily comes to grief among those who are not virtuous. Therefore, if a prince wants to maintain his rule he must learn not to be so virtuous, and to

Faster, Better, Cheaper essays

Faster, Better, Cheaper essays The National Aeronautics and Space Administration (NASA) is a government agency which invents and implements aeronautical, space, and Earth science programs. NASA is currently led by an administrator, Daniel Goldin, who has done a good job leading NASA into the twenty- first century. In the early 1990s, through Goldins leadership, NASA adopted the Faster, Better, Cheaper (FBC) approach to the project management of its space and Earth science missions. The goal was to shorten development times, reduce cost, and increase the scientific return by flying more missions in less time. This goal was driven by politics and funding. Politics play an important part in NASAs management strategies and has led to many changes in management style. Politics for all intents and purposes started NASA. NASA was formed as a result of Russias Sputnik program successes. The official start of NASA was October 1, 1958. NASA inherited the earlier National Advisory Committee for Aeronautics (NACA), and other government organizations, and almost immediately began working on options for human space flight. NASAs first high profile program was Project Mercury, an effort to learn if humans could survive in space, followed by Project Gemini, which built upon Mercurys successes and used a spacecraft built for two astronauts. NASAs human space flight efforts then extended to the Moon with Project Apollo, culminating in 1969 when the Apollo 11 mission first put humans on the lunar surface. After the Skylab and Apollo-Soyuz Test Projects of the early and mid-1970s, NASAs human space flight efforts resumed in 1981 with the Space Shuttle program that continues today to help build the International Space Station. In 1992, NASA Administrator Dan Goldin challenged all of NASA, including its industry and contractors, to do projects in a Faster, Better, Cheaper (FBC) mode. Moving into the last decade of t...

The Inner Person Essay Example | Topics and Well Written Essays - 500 words

The Inner Person - Essay Example It is also made up of the display of a number of characteristics including perseverance and resistance. Courage helps me in facing my strengths, which means that it gives me the will power to believe in my ability to deliver more what the good things I have undertaken before. Most commonly when a person undertakes a certain outstanding achievement, he is tempted to believe that it happened by chance and that it is not possible for such a feat to happen again. But a courageous person would believe in his abilities and try to be a better person than he had been before (Twumasi, 2010) and this is what I have always done. With courage, I have devised the saying that the sky cannot even be my limit because there is enough space beyond the skies. Courage has also helped me in facing my weaknesses. Basically, my weaknesses are those kinds of things that happen to me that are not pleasant and welcoming. For a non-courageous person, when such weaknesses arise, chances are that he would be drawn back and never make a move to rise again. But as a courageous person and as a person having courage as a value, I have always told myself that the downfall of a person is not the end of his life and so even if I fall 1000 times, I shall arise 1000 times. Due to this, I have always given a second chance to myself in trying that very thing in which I failed previously. It is worth emphasizing that my value of courage has transformed my life tremendously. With courage, I was able to land on my very first job, which fetched me so much capital to set myself up in life. It happened that I was confronted by an entrepreneur after he had seen one of my school results and asked me if I could take up a top job in his organization. Even though I was only a student at the time and had no prior experience, I was courageous enough to say yes and that was how my whole economic fortunes changed. Courage has indeed made me and will make

Sales Management Assignment Example | Topics and Well Written Essays - 1000 words

Sales Management - Assignment Example There were also reports of overstating his performance for assigned products. In this regard, as the Sales Director, the following concerns are hereby addressed: a. Explanation on How Paul can Create an Ethical Work Climate in his Department Upon review of the scenario, it was apparent that the top performing salesperson evidently violates codes of conduct by exhibiting unethical behavior, such as use of company resources and time for personal goals and interests; overstating reported individual performance to supposedly comply with the department’s quota, and coercing customers to purchase products with ill-intent. Therefore, to respond to Paul on the ways to create an ethical work climate, the following areas need to be appropriately addressed: i. Policies and rules There is a need to evaluate the policies and rules of the organization in terms of provision and clear dissemination of policies on strict adherence to ethical, moral and legal standards. Likewise, there must be a system of rewards and punishments to impose sanctions for violating these rules and to provide incentives for exemplary performance. There should also be a system of reporting (even through confidential means) of noted violations and appropriate committee to investigate the allegations. If proven that an employee indeed violates policies, sanctions ranging from reprimand, warning, suspension without pay, and dismissal must be enforced. ii. Trust and responsibility The organization must encourage corporate values of trust, responsibility, professionalism and social responsibility. These values must be clearly communicated to all personnel, together with the mission and vision statement; as well as the code of discipline and ethical behavior. Any violations noted on policies, rules, and code of discipline should be subject to sanctions, as recommended. iii. Peer behavior It is the responsibility of colleagues within the organization, irrespective of rank or position, to ensure that ethical behavior is manifested at all times. Any manifestation of unethical behavior contrary to the values indicated and in violation of the policies and rules should immediately be reported to higher authorities for proper review, evaluation, and imposition of sanctions. iv. Bottom line sales emphasis The actions, roles, responsibilities of salespeople and other members of the organization should be noted as contributory to the increase in sales and bottom line (net profit). These financial figures are needed in order for the organization to sustain and support continued operations in the future. In no way should employee behavior be exemplifying conflict of interests by focusing on personal gains and the use of company time and resources. v. Book and Hold Recording future sales transactions in current periods are contrary to the rules in accounting. Any transactions made to comply with sales quota for the current period could not be subject to reversals or refund. In cases that c ustomers refund products purchased, any recorded credits to salespersons’ quotas would be reverted to new levels (after the return) and any rewards or bonus rendered would be deducted in current sales performance. b. Description of the â€Å"Perceived Seriousness† of the Salesperson’s Behavior The behavior manifested and exemplified by the supposedly top performing salesperson is unethical and clearly violates policies, rules, codes of conduct and ethical behav

Baby Bottle Tooth Decay Research Paper Example | Topics and Well Written Essays - 1000 words

Baby Bottle Tooth Decay - Research Paper Example The first advantage associated with acquisition is the undeniably, outright growth of an existing business. For instance if company A buys company B, the size of company A now becomes A+B, which means that there become an outright growth. This outright growth caters for the possibilities associated with starting a business and failing. It also caters for other basic company routines such as recruitment, placement and orientation; some of which do not always end well. Leading on from the first advantage, acquisition ensures that the buyer enjoys a ready-made organizational structure, system and culture. In business, there is no denying the fact that establishing an organization may not be as difficult as establishing or setting up a organizational structure, system or culture. Gourley notes that â€Å"organizational culture is defined as the shared values, norms and expectations that govern the way people approach their work and interact with each other.† This explains the extent to which organizational culture could be difficult for most businesses that are started from the scratch. Buying a company therefore saves an entrepreneur from the hassle of getting a new organizational culture in place. The very last advantage has to do with the inheritance of corporate publicity. Corporate publicity simply refers to the kind of popularity a company has in the eyes of consumers and buyers. These days, most investors target well established and publicized companies when they are buying. This makes it possible for them to inherit the popularity of the existing company. It also makes money voted into publicity very minimal. The best part of inheriting corporate popularity is the inheritance of customers. Customers are the lifeline of every company. It is their inputs that make up the revenues for companies. Building a strong customer base is however very difficult to do. When a person buys an existing company however, he automatically have the customers of the

Harmonics In Domestic Power Consumption Engineering Essay

Harmonics In Domestic Power Consumption Engineering Essay The objectives of this project are to design a model in Matlab/Simulink of a Domestic power system. The model represents a domestic power source and load that contains both linear and non-linear devices. It will be a time-based model which means these devices will be switched ON and OFF at various timings. Means of monitoring the voltages and currents responses are also added to this model and they are discussed in the results discussion part of this report. Finally, harmonic filters are added to the power system and their influence in reducing the harmonics content is observed. The approach taken for this project was to study the methods of simulation using Simulink and the examples related to Harmonics provided by this program. After that, a survey of Non-linear devices was conducted to observe the harmonics effects and to measure the values of the Total Harmonic Distortion (THD) and current amplitudes of the odd orders of the harmonics (i.e. 3rd, 5th, 7th harmonics and so on) of each device using a power quality meter. After completion of the survey, the measurements were added to the model and simulation of the power system is conducted. The results showedà ¢Ã¢â€š ¬Ã‚ ¦. Acknowledgements Table of Contents LIST OF TABLES LIST OF FIGURES CHAPTER 1 INTRODUCTION Background Power system quality has become a major concern for both the power supplier and the end-user especially with the various aspects of power quality disturbance. The impact of harmonics on the modern power systems in specific has become a serious issue to the electrical power utilities and to the costumers as it may cause huge economic losses. The impact of harmonic distortions on domestic power systems can be categorized to two categories: impact on the electrical power utilities of the power supplier and impact on the customer equipment and devices. From the power suppliers prospective, harmonic distortion may harm their major components like transformers, overhead transmission lines and cables. It might cause a reduction in the components lifetime and hence cause economic losses to the power supplier due to maintenance and reinstallation. This, in turn, will increase the system losses and as a result will reduce the efficiency of the power plant. From costumers prospective (residential area or domestic load in this case), a distorted domestic power system will affect the equipment and the devices that are being used. Harmonic distortion may cause them to overheat and reduces their lifetime. As a result, an increase in the electricity bills and economic losses to the customer may occur. The aim behind this project is to have a full understanding about non-linear domestic loads that exist in current residential power systems and their contribution to harmonic distortions. This project consists of a survey of measurements from a number of selected non-linear devices that may have an effect in the domestic power system in term of harmonics. After collecting these measurements, the distortion level will be compared to the international standards and a model will be designed in Simulink to represent the harmonics effect of these non-linear devices and then adding harmonic filters to mitigate their effect. Problem Definition The harmonics distortion produced by the non-linear devices in the domestic load can cause negative impacts on the domestic power system. Both the utilities and the customers are affected economically. Objectives Measuring and evaluating the harmonics that are produced by non-linear devices available in todays domestic loads than model them on Simulink. After that, further analysis and investigation for a solution to this harmonic distortion is to be done. Scope and Limitations This project will be focusing on the domestic loads that are connected to domestic power systems. It will only look into a specific power quality issue, which is harmonics and will disregard any other types of power quality disturbance. For this reason, the mitigation technique to reduce the total harmonic distortion will be considered is a passive harmonic filter. Report organization The final report consists of six chapters which are divided into sections and subsections for a better explanation of the contents of this report. Chapter one discusses about the background of the project and explains briefly the impacts of the harmonics on the utilities and the customers and the relationship between harmonics and the economic losses. It also defines the problem, the objectives and the scope and limitations to this project. Chapter two covers the literature review of research topic. It includes a proper definition of harmonics and lists their effects on power systems in terms of technical and economic losses. Moreover, the chapter gives information about harmonic sources and the available mitigation techniques that can be used to reduce the harmonics distortion. Chapter three is about the practical and experimental work that has been done. It will discuss how the measurements and the evaluation of the harmonic distortion have been done and the equipment that were used. It will also include a subsection about the modelling part of the project and the blocks that were used in Simulink. Chapter four will discuss the results acquired from the experimental work and briefly compare the harmonic distortion of the non-linear devices and the international standard. Chapter five is about conclusion and implications of the project. It includes a final discussion, a conclusion and recommendation for further work or issues to be pursued. CHAPTER 2 Literature Review 2.1 Introduction Power Quality disturbances can be defined as any power disturbance that will lead to voltage, current or frequency fluctuation that result in failure or misoperation of customer equipment. Power quality is considered to be a very important factor due to the fact that power is a part of our daily lives and any interruption or disturbance may cause into several problems such as data corruption, equipment damage, and data transmission errors and reduce equipment life. All these problems can result in huge economic losses to both the utility and the customers. There are several types of power quality disturbances as listed below [4]: Harmonics Transients Short-Duration Voltage Variations Long-Duration Voltage Variations Voltage Imbalance Waveform Distortion Voltage Fluctuation Power Frequency Variations This project will focus on one of the most important power quality disturbances which are harmonics. Harmonics are important to be analyzed as they occur in the industrial loads, residential loads and also in the utility. Analyzing harmonics will help to design a more stable system by applying the appropriate mitigation techniques that reduce harmonics. 2.2 What is Harmonics? A harmonic is a component of a periodic wave having a frequency that is an integral multiple of the fundamental power line frequency 50-60 Hz. Total harmonic distortion is the contribution of all harmonic frequency currents to the fundamental [5]. http://referencedesigner.com/books/si/images/fouriertransform.png 2.3 What is Inter-Harmonics? Inter-harmonics are additional frequencies which are not an integer of the fundamental frequency that can be observed between the harmonics of the power frequency voltage and current. It appears as discrete frequencies or as a wide-band spectrum and can be found in power systems of all voltage classes [1]. There are different sources of inter-harmonic waveform distortion such as static frequency converters, cyclo-converters, induction motors, arching devices and power line carrier signals. The corresponding effects of these inter-harmonics are affecting power line carrier signalling and induce visual flicker in display devices such as cathode ray tubes (CRTs) [1]. 2.4 Harmonic Effects Harmonics have many impacts on the electrical systems and equipment that it may cause overheating for some of the system components which will result in power losses that may decrease the life time of the components which means high economic losses for the utilities. Also if a consumer is having distorted waveforms, it will affect the life time of the equipment therefore again more losses for the consumer as well. Bottom line, harmonics impact is a chain reaction each problem will lead to many other problems [1]. Harmonics cause problems both on the supply system and within the insulation which can be summarized into the following [7]: Overloading of Neutrals: When the loads are not balanced, only the net out of balance current flows in the neutral. Installers (with the approval of the standards authorities) have taken advantage of this fact by installing half-sized neutral conductors. However, although the fundamental currents cancel out, the harmonic currents do not in fact those that are an odd multiple of three times the fundamental, the triple-N harmonics, add in the neutral [8]. 2. Effects on Transformers Transformers are affected in two ways by harmonics. Firstly, the eddy current losses increase at full load with the square of the harmonic number. This results in a much higher operating temperature and a shorter life time. Fortunately, few transformers are fully loaded; however the effect must be taken into account when selecting plant. The second concern is the triple-N harmonics. When reflecting back to a delta winding they are all in phase, which leads the triple-N harmonics to get trapped and circulate in the delta winding and does not get absorbed onto the supply. However, the non-triple-N harmonics can pass through the delta connection winding. The circulating current has to be taken into account when rating the transformer [4]. 3. Nuisance Tripping of Circuit Breakers Residual current circuit breakers (RCCB) operate by summing the current in the phase and neutral conductors if the result is not within the rated limit, disconnecting the power from the load. Nuisance tripping can occur in the presence of harmonics for two reasons. Firstly, the RCCB device may not sum the higher frequency components correctly and therefore trips. Secondly, the kind of equipment that generates harmonics also generates switching noise that must be filtered at the equipment power connection. The filters normally used for this purpose have a capacitor from line and neutral to ground, which might lead into current leakage to ground [4]. 4. Power Factor Correction Capacitors Power-factor correction (PFC) capacitors are provided in order to draw a current with a leasing phase angle in order to compensate for the lagging current that is drawn by the inductive loads such as induction motors. The impedance of the PFC capacitor reduces as the frequency increases, while the source impedance is generally inductive and increases when the frequency increases. As a result, the capacitor is likely to carry high harmonic currents which may lead to it getting damaged, unless it has been specifically designed to with stand that high amount of current [4]. 5. Skin Effect The skin effect is said to happen when the alternating current tends to flow on the outer surface of a conductor. Skin effect is normally ignored as its effect is minor at power supply frequencies. However at above about 350Hz which occurs at the seventh harmonic and above, the skin effect will become significant and will be taken into consideration. As it will be causing additional losses and heating [4]. 6. Induction Motors Harmonics may affect the induction motors in a way that the harmonics may induce a flux to the rotor in an opposite direction to the rotor rotation which will reduce the motor efficiency also harmonics may increase the eddy current in the rotor which therefore will increase heat dissipation [9]. 7. Zero-Crossing Noise Many electronic controllers detect the point at which the supply voltage crosses zero volts to determine when loads should be turned on. This is done because switching inductive loads at zero voltage does not generate transients which may lead into reducing electromagnetic interference and stress on the semiconductor switching devices [9]. 8. Harmonic Problems Affecting the Supply When a harmonic current is drawn from the supply it gives rise to a harmonic voltage drop proportional to the source impedance at the point of common coupling (PCC) and the current. Since the supply network is generally inductive, the source impedance is higher at higher frequencies. Of course, the voltage at the PCC is already distorted by the harmonic currents drawn by other consumers and by the distortion inherent in transformers, and each consumer makes an additional contribution [9]. 2.5 Sources of Harmonics Different non-linear loads produce different but identifiable harmonic spectra. This makes the task of recognizing the harmonics that are produced from those loads easier. Utilities and users of electric power have to become familiar with the signatures of different waveform distortions produced by specific harmonic sources. This will help us figure out better mitigation methods in order to reduce the harmonics produces from the source. This will reduce the harmonics penetration to the electrical power system. At the development of power electronic switching devices, harmonic current propagation was looked at from the perspective of design and operation of power apparatus devices with magnetic iron cores, like electric machines and transformers. At that time the main source of harmonics must have involved substation and customer transformers operating in the saturation region. Harmonics are the by-products of modern electronics. They occur frequently when there are large numbers of personal computers (single phase loads), uninterruptible power supplies(UPSs), variable frequency drives (AC and DC) or any electronic device using solid state power switching supplies to convert incoming AC to DC. Non-linear loads create harmonics by drawing current in abrupt short pulses, rather than in a smooth sinusoidal manner [1]. All variable frequency drives cause harmonics because of the nature of the frontend rectifier design. The 6-pulse rectifier is the standard power circuit elementary configuration for most pulse width modulated variable frequency drives with Diode Bridge rectifiers sold in the marketplace today. Harmonics are generated by non-linear loads, and can be divided into [1]: à ¢Ã¢â€š ¬Ã‚ ¢ Saturable Devices à ¢Ã¢â€š ¬Ã‚ ¢ Arcing Devices à ¢Ã¢â€š ¬Ã‚ ¢ Power Electronics 2.5.1 Saturable Devices Saturable devices are devices which operate under steady state conditions (constant voltage and current). Examples of saturable devices are: à ¢Ã¢â€š ¬Ã‚ ¢ Transformers à ¢Ã¢â€š ¬Ã‚ ¢ Rotating Machines 2.5.2 Arcing Devices Arcing devices are devices that consume high amount of current such as lighting ballasts, arc furnaces, welding machines and fluorescent lamps. à ¢Ã¢â€š ¬Ã‚ ¢ lighting ballasts Electronic lighting ballasts have become popular in recent years because of the overall improved efficiency. The light level can be maintained over an extended lifetime by feedback control of the running current and as result of changing the current it generates harmonics in the supply [1]. Small Uninterruptible Power Supplies (UPS) For high power units, UPS is used. The aim is to make the power supply load look like a resistive load so that the input current appears sinusoidal and in phase with the applied voltage as a result of that UPS is a source of harmonics [1]. Compact Fluorescent Lamps (CFL) The harmonic current spectrum is produced in CFL. These lamps are being widely used to replace filament bulbs in domestic properties and especially in hotels where serious harmonic problems are suddenly becoming common [1]. 2.5.3 Power Electronics Devices Switched mode power supplies (SMPS) Majority of companies use modem electronic units like SMPS. The advantage to the equipment manufacturer is that the size, cost and weight is significantly reduced and the power unit can be made in almost any required form factor. But its disadvantage is that, rather than drawing continuous current from the supply, the power supply unit draws pulses of current which contain large amounts of third and higher harmonics and significant high frequency components [1]. Figure 2.2 Switched Mode Power Supplies (DC-to-DC Converter) 6-Pulse Thyrister Rectifier Variable speed controllers, UPS units and DC converters in general are usually based on the three-phase bridge. The six pulse bridge produces harmonics as 6n (- or +) 1. As we increase Pulse Bridge, harmonics will be less [11]. 2.6 Mitigation Techniques There are many ways to reduce harmonics, ranging from variable frequency drive designs to the addition of auxiliary equipment. The primary methods used today to reduce harmonics are: à ¢Ã¢â€š ¬Ã‚ ¢ 12-Pulse Converter In this configuration, the front end of the bridge rectifier circuit uses twelve diodes instead of six. The advantages are the elimination of the 5th and 7th harmonics to a higher order where the 11th and 13th become the predominate harmonics. This will minimize the magnitude of harmonics, but will not eliminate them. The disadvantages are cost and construction, which also requires either a Delta-Delta and Delta-Wye transformer, Zig-Zag transformer or an autotransformer to accomplish the 30 ° phase shifting necessary for proper operation. This configuration also affects the overall drive system efficiency rating because of the voltage drop associated with the transformer configuration requirement. Transformers Transformers have reactance and resistance which makes it represent the majority of the impedance found in lines feeding non-linear loads. Reactive impedance increases directly with frequency, naturally attenuating harmonics by reducing available current at higher frequencies. This technique is commonly used in reducing the current distortion of electric motor drives in industrial applications. Delta-Delta connected transformers for some drives and Delta-Wye connected transformers for the remaining drives are used in order to trap the triple-n harmonics. This will lead into current distortion reduction [7]. Line Reactors This method consists of connecting a line reactance in series with the harmonic source at which the reactance will reduce the harmonic current. However, the line reactance method has different advantages and disadvantages as shown in the Table 2.l[12]. Advantages Disadvantages Low Cost Harmonics reduction is insignificant Available in different values Dynamic characteristics depend on the line capacity Small power losses At very low load conditions it may damage the line due to high harmonic currents Table 2.1 Advantages and disadvantages of Line Reactors The amount of harmonic that can be reduced is a function of the impendence of the line reactor the higher the line impendence the higher the reduction in harmonics. Active Filters Active harmonic filters uses power electronic devices in order produce harmonic current components that cancel the harmonic current components that are produced by the nonlinear loads. The active harmonic filter is configured based on a pulse width modulated (PWM) voltage source inverter that interfaces to the system through a system interface filter. The active filter configuration that is shown in Figure 2.6 is referred as a parallel active filter as the filter is connected in parallel with the nonlinear load that is compensated. Figure 2.6 show the concept of the current cancelation so that the current being supplied from the source is sinusoidal. The voltage source inverter is used in the active filter in order to control the harmonics. This inverter uses dc capacitors as the supply and can switch at high frequencies to generate a signal that can cancel the harmonics produced by the non-linear loads. The voltage distortion is reduced because the harmonic currents that flow through the source impedance are reduced [13]. http://ars.els-cdn.com/content/image/1-s2.0-S0019057811001133-gr1.jpg Passive Filters Passive filters consist of capacitor, inductor and a resistor connected in parallel to a nonlinear load. Passive filters will provide a low impedance path for the harmonic current therefore will inject them to ground. Passive filters can be tuned to absorb one type of harmonic current or several types as shown in the Figure 2.7 [14]. Figure 2.7 Passive Tuned Filters: (a) Single Tuned (b) Double Tuned Another important feature of the passive filters is that they can improve the power factor since they have a capacitance in their construction. Moreover, filters can be specified according to the connection type into two main groups, the series connection and parallel. The filters power losses depends on the material used so the lower the losses the higher the cost of the filter so after all its a trade of between the power losses and the filter cost [15]. In conclusion, many techniques by which harmonics can be mitigated from the system but always there are some advantages and disadvantages for each technology which makes it appropriate for some applications and not for others. Moreover, the decision of using which mitigation technique depends mostly on the cost, reliability and power losses. Always important to keep in mind that theoretical calculation and assumptions for the type/size of mitigation technique does not always match with the practical findings due to some voltage disturbance and phase unbalancing. 2.7 Harmonic Evaluation and Measurements 2.7.1 Introduction Evaluating harmonic system is a very important step in the analysis and design process. In order to evaluate the harmonics sources we should follow some standards that are set by IEEE as they have specified some guidelines and limits that we should follow. Following those guidelines will be helpful during measurements and understanding the devices used. 2.7.2 Harmonics Limits There are many standards which have been set by many organizations (national/international) in order to improve the quality of service provided and to protect the customers from all different effect of disturbances that may occurs in electrical systems. For this project we will discuss the limits specified by the Institute of Electrical and Electronics Engineers. 2.7.3 Institute of Electrical and Electronics Engineers (IEEE) According to IEEE 519-1992 standards the total voltage distortion and the total current distortion limits should be within the specified limits as shown in Table 3.1 and Table [2]: Table 3.1 Total Voltage Distortion Limits According to IEEE 519-1992 Table 2.7 Total Current Distortion Limits According to IEEE 519-1992 SCR is the ratio of the maximum short circuit current to the maximum fundamental frequency load current at the point of common coupling (PCC)[]. 2.7.4 Harmonics Evaluation Harmonic currents produced by nonlinear loads can interact with the utility power supply. This interaction often gives a rise to voltage and current harmonic distortion observed in many places in the system. Therefore, to limit both voltage and current harmonic distortion, as seen in the limits set by the IEEE standard 519-1992 in order to limit the harmonic current injection from the end users to make the harmonic voltage levels on the overall power system acceptable [8]. The two most common used indices measuring the harmonic waveform are: à ¢Ã¢â€š ¬Ã‚ ¢ Total Harmonic Distortion (THD) à ¢Ã¢â€š ¬Ã‚ ¢ Total Demand Distortion (TDD) Since there are two parties involved in limiting the total harmonic distortion which are divided between the utility and the customers, the evaluation is divided into two parts which are: à ¢Ã¢â€š ¬Ã‚ ¢ Measurements of the currents that are being injected by the loads à ¢Ã¢â€š ¬Ã‚ ¢ Calculations of the frequency response of the system impedance The total harmonic distortion (THD) is a measure of the effective value of the harmonic components of a distorted waveform relative to the fundamental. In order to calculate the total harmonic distortion for the voltage or current Equation (1) or (2) are used [1]: (1) (2) The total demand distortion (TDD) is expressed in terms of the maximum demand load current. TDD can be calculated using Equation (3) [1]: (3) In computing the short circuit level at the point of common coupling the normal system condition that will result in minimum short circuit level will be taken into consideration as it causes the most severe impact to the system. The short circuit current can be calculated using Equation (3.3) [8]: Where MVA and kV represent the three-phase short-circuit capacity in megavolt amperes and the line-to-line voltage at the point of common coupling in kV, respectively. The load current should be evaluated in order to determine the short circuit ratio Equation (3.4) can be used to calculate the load current [8]: 3.6 How to Evaluate Compliance Harmonic currents produced by nonlinear loads can interact adversely with the utility supply system. The interaction often gives rise to voltage harmonic distortion and current harmonic distortion observed in many places in the power system. Therefore, it is required to identify the point of common coupling (PCC) in order to have a more accurate measurement and evaluation. For industrial and commercial end users, the PCC is usually at the primary side of a service transformer that supplies the facility as shown in figures 3.1 and 3.2.

Hawthornes Scarlet Letter - Rev. Arthur Dimmesdale and the Scaffold Scenes :: Scarlet Letter essays

The Scarlet Letter   - Dimmesdale and the Scaffold Scenes In Nathaniel Hawthorne's "The Scarlet Letter," there are three very important scenes that all take place at the town scaffold, a place of great shame in their strict Puritan society. These scenes represent the progression of Reverend Arthur Dimmesdale over the course of the story. Each scene involves him in some way and one can easily see that he has changed dramatically in all three. The first scaffold scene takes place in the very beginning of the story. Hester Prynne, a woman who has committed adultery and will not name the father of her child, is forced to stand upon the scaffold in shame for three hours in front of a crowd of people. Dimmesdale, who is later revealed as the father, openly denies his sin and even goes as far as telling Hester to "speak out the name of thy fellow-sinner and fellow-sufferer," in order to make sure that nobody suspects him. While the author doesn't make his guilt very obvious, he does give a few hints that suggest Dimmesdale does have some sort of hidden secret. In this scene, the Reverend shows his original strength of character, which he slowly loses over the course of the story. Seven years later, in the middle of the night, Dimmesdale finally admits to his sin while standing on the scaffold, just as Hester did so very long ago. It has been eating away at him all this time and feels that he also must be punished, though he cannot bring himself to confess publicly. He even brands his chest with the same letter "A" that Hester has been forced to wear upon her clothing to show that she is an adulterer. In the third and final scaffold scene, Dimmesdale finally reveals his secret to the public. And as "Pearl kissed his lips...a spell was broken," Dimmesdale conquers his guilt and dies right there on the scaffold with an open conscience. He also escapes