Explain and Evaluate How Markets Create New Forms of Authority Essay

Explain and Evaluate How Markets Create New Forms of Authority - Essay Example Decentralization engulfs varied concepts that must be understood and controlled before setting any business programs, or projects. Therefore, the need for authority in this sense is to support reorganization of administrative, financial and service delivery within that business venture effectively (Taylor, 2010; p. 122). Notably, authority can be understood in the terms or application of the decentralization concepts since it refers to responsibility and authority for public functions, especially of the central government to quasi or subordinate independent government organization or private sectors (Smith & Sutherland, 1998; p. 319). How markets create new forms of authority is a complex multifaceted concept since it involves wide understanding varying from different characteristics, conditions for success, and policy implications. Numerous forms of authorities influence different markets; therefore, there is a rising need for markets to from authorities that makes them autonomous. However, most of these authorizes are influenced by other factors including political, fiscal, administrative, and other market authorizes that are pegged of different types of markets or market decentralizations (Smith & Sutherland, 1998; p. 219). Hence, there is a need to highlight concepts differentiating each form of authority as well as the need to coordinate these authorities. Moreover, different markets affect and apply to political, fiscal, and administrative authorities differently across different market domains and regions or countries. The demanding nature of the economy has made different market demands to reshape or reform the political authorities. The political authority often aims at giving the elected representatives immense power in public decision-making (Le?cuyer, 2002; p. 137). This form of authority is associated with representative government and pluralistic politics; however, it can lead to decentralization by giving the elected representatives, or citizens, more influence to the implementation of the national policies (Taylor, 2010; p. 122). Some of these policies used to determine what business and business performs were to engaging in business within what political domain. However, markets have so far changed and political policies are being redefined to accommodate or allow their citizens and government to engage in businesses within a large market domain. The political authorities have been forced to advocate for flexibility in their marketing and market policies; otherwise, they will remain powerful without powerful or reasonable economies to control (Ferguson, 1995; p. 173). Therefore, different markets have forced different political authorities to assume certain decisions that will all greater participation with more relevant and better-informed diverse interests of societies and other national or international authorities (Smith & Sutherland, 1998; p. 219). These reforms or concept implies that markets have forced or is curre ntly compelling the public or citizens to elect representatives with better political policies towards marketing and markets. The actions of any political authority require statutory or constitutional reforms towards developing pluralistic political policies that will be friendly to markets. Markets have led to administrative decentralization with the aim of distributing administrative authorities towards effective market management. It influenced the administrative decentralization to redistribute responsibility and financial resources authorities towards providing the public services with different levels of governances in order to understand market demands and requirement at

Women Rising From the Ashes of War Essay Example | Topics and Well Written Essays - 1000 words

Women Rising From the Ashes of War - Essay Example Women Rising From the Ashes of War When World War Two broke out, it was a signal that turbulent times were ahead. Men were recruited to fight for their countries. Women had no choice but to let go of their men. It was unknown to everyone what the future will bring, but when the war broke out, it seemed that a bleak tomorrow threatened the world. Women, in particular, assailed by a series of unending attacks to their humanity and had to claw at what appears to be a hint of hope for survival. Class distinctions broke down and the formerly rich women adjusted to life’s painful realities that they had to live like the rest of the commoners. â€Å"Mass observation surveys conducted during 1941 found that many who advocated conscription believed it would force ‘idle rich girls’ to work.† (Smith: 215) The war demanded enormous manpower, not just in the armed forces, but also in industry. Millions of men joined the forces, which left many industries without a satisfactory workforce. The government realised that this shortfall had to be filled, approximately one and a half million workers were needed in munitions alone and it was vital to keep up the production of essential wartime machinery and equipment. The government therefore, took the decision to draft women into ‘men’s’ jobs, just as they had done during the First World War, in an attempt to keep production at a steady level. The new realities faced by the women necessitated that they likewise take part in the war effort in any capacity they can. Most women had to leave their homes to work in a variety of occupations.

Explain and Evaluate How Markets Create New Forms of Authority Essay

Explain and Evaluate How Markets Create New Forms of Authority - Essay Example Decentralization engulfs varied concepts that must be understood and controlled before setting any business programs, or projects. Therefore, the need for authority in this sense is to support reorganization of administrative, financial and service delivery within that business venture effectively (Taylor, 2010; p. 122). Notably, authority can be understood in the terms or application of the decentralization concepts since it refers to responsibility and authority for public functions, especially of the central government to quasi or subordinate independent government organization or private sectors (Smith & Sutherland, 1998; p. 319). How markets create new forms of authority is a complex multifaceted concept since it involves wide understanding varying from different characteristics, conditions for success, and policy implications. Numerous forms of authorities influence different markets; therefore, there is a rising need for markets to from authorities that makes them autonomous. However, most of these authorizes are influenced by other factors including political, fiscal, administrative, and other market authorizes that are pegged of different types of markets or market decentralizations (Smith & Sutherland, 1998; p. 219). Hence, there is a need to highlight concepts differentiating each form of authority as well as the need to coordinate these authorities. Moreover, different markets affect and apply to political, fiscal, and administrative authorities differently across different market domains and regions or countries. The demanding nature of the economy has made different market demands to reshape or reform the political authorities. The political authority often aims at giving the elected representatives immense power in public decision-making (Le?cuyer, 2002; p. 137). This form of authority is associated with representative government and pluralistic politics; however, it can lead to decentralization by giving the elected representatives, or citizens, more influence to the implementation of the national policies (Taylor, 2010; p. 122). Some of these policies used to determine what business and business performs were to engaging in business within what political domain. However, markets have so far changed and political policies are being redefined to accommodate or allow their citizens and government to engage in businesses within a large market domain. The political authorities have been forced to advocate for flexibility in their marketing and market policies; otherwise, they will remain powerful without powerful or reasonable economies to control (Ferguson, 1995; p. 173). Therefore, different markets have forced different political authorities to assume certain decisions that will all greater participation with more relevant and better-informed diverse interests of societies and other national or international authorities (Smith & Sutherland, 1998; p. 219). These reforms or concept implies that markets have forced or is curre ntly compelling the public or citizens to elect representatives with better political policies towards marketing and markets. The actions of any political authority require statutory or constitutional reforms towards developing pluralistic political policies that will be friendly to markets. Markets have led to administrative decentralization with the aim of distributing administrative authorities towards effective market management. It influenced the administrative decentralization to redistribute responsibility and financial resources authorities towards providing the public services with different levels of governances in order to understand market demands and requirement at

Is it better to use GDP per Essay Example for Free

Is it better to use GDP per Essay Many numbers could be calculated to make a judgment on an economy. But we need a general number that measures the total economys strength, but is it better to use the cruel GDP number to measure the level of growth of a particular economy, or calculate the GDP per head number to get a better judgment? On March 13th under the title of Grossly distorted picture in the Journal The Economist an article talked about that issue and compared between the two measures with evidences and examples. The writers opinion The writer tries to grab our attention to the fact that maybe using the total GDP does not show the real state of the economy, but a better way to measure the economy is the GDP per head which the writer is considering it a rough guide to average living standards. (GDP, 2008). So, according to the writer (2008) opinion the amount of total GDP doesnt necessarily indicates to the real growth of the economy, even sometimes the level of economic growth in a particular country could be higher than another country that has a higher GDP number because of the lower level of growth in population. The writer (2008) in this article demonstrates two obvious examples which they are America and Japan, while the US economy made a growth of 2. 9% Japans economy made a growth of 2. 1%, so most people would say immediately that the US economy scored better but we must consider also the level of population growth, while the GDP per head growth in US was 1. 9% it scored 2. 1% in Japan, higher domestic increase in population and a very high level of new people come from abroad cause a 1% growth in population, but in Japan the GDP per head growth reached the level of 2. 1% because Japans population has been decreasing. (GDP, 2008). Shortcomings Anonymous (2008) also gives other example of how using GDP per head tells a completely different story than using the GDP, as using the GDP growth doesnt necessarily provide the right image of a countrys welfare, but population growth must be regarded too. The writer (2008) provides examples like Brazil which has been in a fast growing economy, but for the last fast year the GDP per head increase by only 2. 3% because of the high growth of population, and the writers (2008) gives the opposite example which is Russia who has a GDP growth near the level of Brazil, but yet still the GDP per head tripled for Russia because population rapidly decrease. In general, the GDP is a tricky measure but GDP per head provides a clearer image according to what the writer (2008) say. Should recession be redefined? the standard definition of a recession—a decline in real GDP over some period . (GDP, 2008). But, should this definition still be used? The writer (2008) disagrees with that as recession doesnt necessarily mean an actual decrease in GDP but simply a decrease in GDP per head, and for example he imagines that in Japan where the population is decreasing if the GDP growth was 0% the GDP per head will increase, but in America the GDP per head growth will be considered dropping over the past couple of months because the population growth exceeded the GDP growth, so the writer (2008) suggests that the right definition of recession should be a fall in average income per Person. Conclusion The writer (2008) suggests GDP per head not just for the fact the GDP per head considers the growth of population, but he thinks that using GDP per head can boost up economies. By giving Japan as an example the writer (2008) recommends that government announces GDP per head which is increasing because of decreasing population instead of disappointing GDP number, this will make people optimistic and make them consume more and economy gains. References Grossly distorted picture. (2008, March 13). Retrieved April 6, 2008, from http://media. economist. com/finance/displaystory. cfm? story_id=10852462

Literature Review Of Load Shedding Methods

Literature Review Of Load Shedding Methods In chapter 1, a brief discussion about active distribution networks was presented. The importance of operation of islanded distribution networks was discussed. This chapter is intended to give the reader a better understanding of the load shedding methods currently applied and proposed over the years. However, it is assumed that the reader is familiar with basic power system engineering. In section 2.2, the area of probability of islanding and the need for load shedding is discussed. To achieve this objective, existing load shedding methods are reviewed to understand their working principle, requirements, advantages and limitations. The main categories identified are the following (i) Manual / SCADA Load Shedding (ii) Load Shedding using thresholds, (iii) Adaptive Load Shedding, (iv) Intelligent Load Shedding and (v) Load Shedding Based on Static Optimisation which are described and discussed in sections 2.2 through 2.7 respectively. Finally a summary is given in section 2.8 from which a new load shedding method for an islanded distribution network able to address the limitations of existing methods will be proposed. probability of islanding There is by now a considerable amount of literature on load shedding. That most of the literature however deals with large interconnected systems. For smaller systems when a loss of mains / grid event occurs the islanded distribution network have different operating characteristics and restrictions that require different load shedding guidelines. These are due to the low inertia of the distributed generators, the limited spinning reserve and limited communication systems [0] [0]. Load shedding is a practice used power system and serves as a function to try to arrest any frequency or voltage drop when a fault isolating part of the distribution network occurs. Faults in power systems are inevitable, for various reasons such as adverse weather conditions, ageing and failure of equipment, accident, and animal contact. In general, faults happen when an abnormal physical contact occurs between lines or on lines to earth that create a short-circuit path. If the system is not well protected, the high fault current due to the short-circuit path can cause damage to the equipment in the system. Faults also affect the reliability and quality of the power supply, leading to power interruption by frequency and voltage collapse and voltage sag events. Regardless of the interruption period, the losses are often enormous both to the customers and power utility companies. There are two types of fault, determined by the physical nature of the short-circuit path: temporary or permanent. Common causes of temporary faults on overhead lines are lightning strike resulting in a flashover of the insulator; bird or animal contact; and momentary contact due to wind or trees. Faults caused by these events exist for a very short period of time. On the other hand, a permanent fault remains in the system until the short-circuit path is removed. Common causes of permanent faults in power system networks are cable insulation failure, objects falling on the overhead lines, dirt on insulators and lines falling to the ground. When faults occur, a protection device operates to isolate the faulty line from the rest of the system (loss of mains / grid). The generators designated to provide voltage and frequency control will respond to control the island voltage and frequency. In order to achieve smooth transition to island operation, the generators must firstly ride through the fault or failure and secondly act to balance the active and reactive power in the islanded network. With a carefully designed load shedding method the operation of the islanded distribution network might be possible. It is important however that the design of the load shedding method is designed on the understanding of the characteristics of the system involved, including system topology and dynamic characteristics of its generation and load. A poorly design method may be ineffective and eventually lead to total customer interruption. Over the years, however, utility experience and extensive studies on a number of systems have resulted in different methods guidelines. In the following section, principles and guidelines for load shedding methods are reviewed. manual / SCada Load Shedding Manual or operator initiated load shedding [0] is not a reliable method to be used to avoid frequency deviation. However it can be used by some utilities to manually shed load or open ties (interconnectors) with adjacent areas at a frequencies below automatic underfrequency thresholds. This type of action might be necessary to prevent any further frequency deviation and to recover the frequency back to the nominal value. This load shedding scheme cannot be used for the islanded distribution network as it will be very slow as the frequency and voltage in the network will collapse within few seconds making it impossible for the operator to decide the correct defence action required for safe operation. automatic Load Shedding using thresholds An automatic load shedding for transmission system using different schemes such as underfrequency, undervoltage and combinations of the two can be employed to avoid frequency or voltage collapse during a significant imbalance between generation and load. These types of load shedding methods are very dependant on off line studies of the systems dynamic performance and only consider the greatest probable imbalance between generation and load. These methods have to be coordinated with the protections of the generating units, shunt capacitors and other automatic actions that occur in the system during frequency and voltage variations. Underfrequency load Shedding The underfrequency load shedding scheme as explained in the following papers [0] [0] uses relays detecting the systems frequency. These are designed to operate on the instantaneous frequency value where they trip when the frequency drops below the set point of the relay. The shedding is accomplished in the systems distribution or transmission stations where major load feeders can be controlled by tripping of the circuit breakers (CB) automatically. Different settings can be applied in these load shedding schemes. Multiple stages can be used in the scheme [0]. The substation loads can prioritised and grouped according to the importance of the load. The relays can be set to control one or more groups of loads and when there is a frequency drop these can be disconnected sequentially where the group with the highest probability being disconnected the last. Each group disconnected should contribute to the system rate of change of frequency decline. If the load to be disconnected is small compared to the overall imbalance then the contribution will be insignificant and would cause further problems to the systems frequency decline. Another setting usual for this type of scheme is the time delay [0]. The time may can be required and used usually to avoid any frequency transient dips that could arise in the system. The time delay also avoids unnecessary load shedding by allowing the load / frequency controls in the system to respond to the frequency deviation. However load shedding performed with long time delays should be set appropriately as it will make the system more vulnerable to system stability if eventually load shedding is required. This method will work adequate in a situation where the system frequency decline is slow. For example, as discussed in [0], in the UK as stated in the NationalGrids GridCode each transmission area has to disconnect a defined percentage of the peak Demand that each Network Operator whose system is connected to the GB Transmission System shall disconnect by low frequency relays at a range of frequencies. The defined frequencies and the amount of loads are given in Table 1 -1. Table 1à ¢Ã¢â€š ¬Ã¢â‚¬Ëœ1: Load Shedding Scheme employed in the UK Frequency (Hz) % Demand disconnection for each Network Operator in Transmission Area NGET SPT SHETL 48.8 5 48.75 5 48.7 10 48.6 7.5 10 48.5 7.5 10 48.4 7.5 10 10 48.3 48.2 7.5 10 10 48.0 5 10 10 47.8 5 Total % Demand 60 40 40 The percentages in Table 1 -1 are cumulative such that, for example, should the frequency fall to 48.6 Hz in the NGET Transmission Area, 27.5% of the total Demand connected to the GB Transmission System in the NGET Transmission Area shall be disconnected by the action of low frequency relays. A significant drawback of this method is that the systems frequency must be already be low before the relay can operate which can delay the load shedding action and the frequency recovery of the system. Additionally these types of schemes usually shed more than the required amount of load. Undervoltage load Shedding Undrevoltage load shedding method has been successfully deployed in transmission systems to protect them from voltage collapse [0] [0]. System studies are required to determine which systems are potential candidates for suitable the undervoltage load shedding method. This method is most useful in slow decaying systems where the undervoltage load shedding relay time relays can coordinated accordingly and operate to alleviate the system from overload conditions and low voltages. Voltage collapse can be studied using steady state simulations for the identified areas using a power flow analysis. System planning engineers conduct numerous studies using P-V and Q-V as well as other analytical methods to determine the amount of load required to be shed to preserve voltage stability under different disturbances. Dynamic simulations can then determine the speed of the collapse and load shedding settings. An example as discussed in [0] in the US in the Puget Sound area, which is prone to voltage collapse has been studied. The voltage trip thresholds were determined from the results of steady state simulations of worst contingencies. The time delays for the relays were coordinated to address control actions of the automatic capacitor switching, generator limits, on load tap changing transformer using dynamic simulations. Table 1à ¢Ã¢â€š ¬Ã¢â‚¬Ëœ2: Load Shedding Scheme employed in the US Voltage (pu) Time delay (s) % Demand disconnection for Network Operator in Transmission Area 0.90 3.5 5 0.92 5.0 5 0.92 8.0 5 When the monitored bus voltages fall to 0.90 pu or lower for a minimum of 3.5 s then 5% of the load is disconnected. Additionally another 5% of load disconnection should occur when the voltage falls to 0.92 pu or lower for 5.0 s. There limitation associated with proper application of undervoltage load shedding is the location of its application.to where the relaying may be appropriately applied. If it is placed on a distribution line the effects of auto tap changers mask a system overload condition from the relay, or alternatively a line switching operation or the startup of a large industrial plant on one feeder could fool the relay. The relay would not be appropriate at locations directly adjacent to generation powerful enough to control bus voltages even during severe overloads. The relay is best applied to locations with fairly stiff voltages under all normal conditions, so a low voltage condition will reliably indicate a severe overload condition, as may be assumed to be the case at large substations associated with bulk power transmission lines and therefore this method cannot be effectively applied in islanded distribution networks where DG unit power and load demand varies. combination load Shedding In order to increase the security of the above discussed methods for underfrequency load shedding the relay could be set up to supervise the voltage, the current or the rate of change of frequency. According to their combined settings, the relay could either be blocked or initiate tripping of the CB to avoid any misoperations. One combination load shedding scheme is to use an underfrequency load shedding relay with voltage supervision. Basically the operation procedure of load shedding is blocked from operating unless the voltage is below a given threshold. The underfrequency relay will be able to trip the CB as long as the bus voltage it is monitoring is lower than a set point. Another combination is to use current supervision instead of the voltage. The purpose of the current supervision is to select which feeders to trip. This can achieved by monitoring which feeders are loaded above a certain point and then the relay will initiate the load shedding signal. An alternative is to use the rate of change of frequency for supervision [0] [0]. During a disturbance the supervision of the rate of change of frequency can block the tripping for very fast frequency changes but would allow for typical frequency decay rates. Also instead of measuring the instantaneous rate of change of frequency supervision is to use the frequency change trend. In other words by monitoring the average rate of frequency change will provide a more secure decision for tripping during disturbances. The load shedding decision of the scheme is made by monitoring the frequency change over a specified amount of time usually few hundred milli seconds. Therefore making the operation of the relay slower than the ones employing the rate of change of frequency. automatic ADAPTIve Load Shedding Adaptive control involves updating the amount of load to shed used by the method to cope with the fact that the conditions such as the power imbalance between generation and load of the system are time-varying or uncertain. It is important in these circumstances to minimise consumer disruption through proper design of the load shedding arrangements. An adaptive load shedding, is based on the relays reacting to a disturbance either by being instructed the amount to shed or by having certain defined criteria based on the rate of change of frequency. Anderson and Mirteydar in [0] present an adaptive methodology for setting of underfrequency relays that is based on the initial rate of change of frequency at the relay. The frequency performance of the islanded is represented by a linear system frequency response as shown in Figure 1 -1 and presented in more detail in the literature in [0]. Figure 1à ¢Ã¢â€š ¬Ã¢â‚¬Ëœ1: Simplified frequency response with disturbance input where: H = inertia constant (s) FH = fraction of total power generated by HP turbine TR = reheat time constant (s) Km = mechanical power gain factor R = droop characteristic (pu) D = damping factor Clearly the only observed quantity that gives any clue as to the size of the disturbance is the initial slope of frequency decline. The use of the initial slope to estimate the magnitude of the disturbance requires that every substation in the island will observe slightly different slopes and will therefore shed load based on different estimates of the disturbance. However on average the system as a whole will shed approximately the correct amount of load. To set the parameters for the relays as explained they are based on a simulation of the frequency response for the system. In the example given (H = 3.5 s, FH = 0.3, TR = 8.0 s, Km = 0.85, R = 0.06 and D = 1) the evaluation of the frequency and its slope against different amounts of disturbances are given in Table 1 -3. Table 1à ¢Ã¢â€š ¬Ã¢â‚¬Ëœ3: Initial Slope and Maximum Deviation vs Upset (frequency nominal 60 Hz) Pstep df/df ΆÃƒ Ã¢â‚¬ °max fmin pu pu/s Hz/s Hz Hz -0.2 -0.0286 -1.7143 -1.6438 58.356 -0.3648 -0.0521 -3.1260 -3.0000 57.000 -0.4 -0.0571 -3.4286 -3.2876 56.712 -0.6 -0.0857 -5.1429 -4.9313 55.069 -0.8 -0.1143 -6.8571 -6.5751 53.425 -1.0 -0.1429 -8.5714 -8.2189 51.781 The lowest frequency permitted in the system is 57 Hz from the nominal 60 Hz. Therefore when a magnitude greater than -0.0521 pu/s is observed load shedding must be triggered. This method relies on the fact that the amount of load shedding is a function of only the inertia constant and the observed slope. The inertia constant is the rotating kinetic energy of all units in the island divided by the total connected volt ampere rating of the units. This parameter has to be estimated. Therefore, the initial slope is the only unknown. The load shedding amount is computed in per unit, which makes it easy to apply to every load and to every load shedding relay. A positive is that communication is not required between relays and the boundaries of the island are not required to be known. However the drawbacks are that if it is applied for the islanding application of islanded networks this might not be possible as the method needs good estimates of the inertia of the system D, R, TR, Km and FH. This can significantly change with the varying DG units and loads in the distribution network. Another adaptive load shedding method presented by Terzija in [0] uses similarly as the previous method a variation of the typical swing equation. Due to the dynamic responses of turbines, governors, other control actions, spinning reserve, loads are not taken in account in the calculation of the required amount of load to be shed as given in . Where H is the inertia constants and assumed to be known in advance to the disturbance. The adaptive approach is based on real time estimation of fc (frequency of equivalent inertial centre) which is proposed to be calculated centrally by measuring the local frequencies at each generator. The proposed method assumes that the time constants in the power system are large and with modern communication this method would be possible for big power systems. However in distribution networks communication is believed not to change drastically in the near future making this application difficult to implement. This is because the estimation and control information are evaluated after the disturbance occurred. Van Cutsem and Otomega proposed a method in [0] which relies on a set of load shedding controllers distributed over the region susceptible to voltage instability. Each controller monitors the bus voltage and act on a set of loads located at that bus. Each controller acts when its monitored voltage falls below some threshold and trips at different time according the severity of the drop. The action can be repeated until the voltage is above the threshold voltage. The principle of operation of the controller is described as follows. The delay à Ã¢â‚¬Å¾ depends on the time evolution of V as follows. A block of load is shed at a time t0 + à Ã¢â‚¬Å¾ such that: where C is a constant to be adjusted. This control law yields an inverse-time characteristic: the deeper the voltage drops, the less time it takes to reach the value C and, hence, the faster the shedding. The larger C, the more time it takes for the integral to reach this value and hence, the slower the action. Furthermore, the delay is lower bounded: to prevent the controller from reacting on a nearby fault. Indeed, in normal situations time must be left for the protections to clear the fault and the voltage to recover to normal values. Similarly, the amount ΆPsh of power shed at time t0 + à Ã¢â‚¬Å¾ depends on the time evolution of V through where K is another constant to be adjusted, and ΆVav is the average voltage drop over the [t0, t0 + à Ã¢â‚¬Å¾]interval, i.e., Moreover, the whole system will tend to shed first where voltages drop the most. This location changes with the disturbance. Hence, the proposed scheme automatically adjusts the shedding location to the disturbance it faces. Note that the above features are achieved without resorting to a dedicated communication network. The controllers do not exchange information, but are rather informed of their respective actions through the power system itself. The drawback for this method for distribution network is that the tuning which consists of choosing the best values for Vth, C and K. A C and K combination suitable can be identified by minimising the total load shedding over all disturbance scenarios. Clearly this method would shed more loads for some scenarios. An additional concern is that the dynamic performance of the DG units and loads is not taken in account when performing load shedding if applied to the islanded distribution network and by trying to shed in steps the frequency drop in the network might drop significantly. automatic Intelligent Load Shedding Applications of intelligent load shedding in power system engineering (e.g. genetic algorithms, artificial neural networks, MonteCarlo etc.) have been demonstrated in [0] [0]. The characteristics which are inherent to intelligent methods, such as the ability to learn and generalization make it feasible for applications such as load shedding. You et al. in [0] discuss of a method that uses the rate of change of frequency to load shed. The method uses the same approach to calculate the required amount of load as in [0] and at the same time, the conventional load shedding method with undefrequency thresholds is incorporated to form a new two level load shedding method. The conventional load shedding method has longer time delays and lower frequency thresholds which can be used to prevent unnecessary load shedding in response to small disturbances. If the disturbance is large, the second layer will be activated and a block signal to the first layer is enabled. The second layer based on the rate of change of frequency load shedding will shed more load quickly at the early stage of the disturbance. Similarly as to paper [0], this method will have the same limitations when applied to the islanded distribution network. In the paper [0] which follows this study, the explanation of the selection of the settings for the relays is discussed. Agent technology is to try to assure that the method will withstand all possible disturbances. Traditionally after a major disturbance, the system is revisited and settings of devices and control actions are changed so that the system will withstand the same disturbance in the future. This however due to analysis of the system significant time and cost will be required. For the autonomous and adaptive learning capability for the agents, the reinforcement learning technique is used. Reinforcement learning is learning by interaction. The agent tries actions on its environment and then, the tendencies of taking particular actions are reinforced by receiving scalar evaluations of its actions. Thus determining the amount of load to be shed required to avoid collapse. The paper does not discuss whether the technique is applied online or offline through simulation. Clearly for the online this would not be ideal as it will take a lot of number of failures until the agents are properly set for that particular disturbance. For the offline simulation a concern is that for islanded distribution networks the topology, DG unit power and load demand will change thus making the decision of the action of the agents is difficult to train. Another concern is communication between agents. Fast communication would be required for coordinated decisions. Another approach to load shedding is the use of fuzzy expert system and is described in [0]. In this paper Sallam and Khafaga described a method to control the voltage instability by load shedding using fuzzy technique as fuzzy controller. The operation of the method relies on the experts knowledge which is expressed by language containing ambiguous or fuzzy description. The aim of this study is to design and analyse a fuzzy controller for the study to control against load and voltage instability by calculating the optimum load shedding as output. Similarly in [0] the authors propose genetic algorithms for the optimum selection of load shedding. These techniques search and optimise the amount of load shedding using objectives and constrains required for a practical load shedding method. Also in [0] the authors introduce another technique using the artificial neural networks is presented. To prepare the training data set for the artificial neural network, transient stability analysis of the power system is required and to find the minimum load shedding for various scenarios. By selecting the total power generation, total load demand and frequency decay rate as the input neurons for the method, the minimum of load shedding is determined to maintain the stability of the power system. In paper [0] Thalassinakis and Dialynas introduce a computational method using MonteCarlo simulation approach for the calculation of the settings of the underfrequency load shedding relays is discussed. The frequency performance as previously discussed in section 1.5 is used here as well. The strategy for the relay settings will be determined against amount of load to shed, time delay, rate of change of frequency and underfrequency level. A new strategy is developed by changing these settings. The MonteCarlo then computes the system through reliability indices of generating units, the system frequency and load shedding indices. load shedding based on static optimisation The first theory of applying load shedding using an on line dynamic simulation of the power system network was introduced by La Scala et al. [0]. Followed by an improvement of the method combing a control action to ensure angle and voltage stability enhancement in [0]. The first paper that introduced the same concept applied for large power systems to the smaller distribution network is described in [0] by Nelson and Aponte. A more recent study using similar technique is also presented in [0]. The paper presented in [0] describes the philosophy and the implementation of a preventive load shedding control algorithm for the application in dynamic security assessment. The methodology is based on nonlinear programming techniques, for assessing control actions to guarantee the dynamic security of power systems. The basic idea is that the online dynamic preventive control can be seen as a static optimisation problem with minimising function and equality and inequality constrains. The equality constrains consist in the discretisation at each time step of the differential algebraic set of equations representing the power system. The inequality constrains define a domain where the system trajectories should be contained in order to satisfy the requirements for the system performance stability and steady state voltage dips. In [0] the formulation includes corrective actions based on load shedding. The proposed method assumes that the analysis is performed to detect particular disturbances threatening the dynamic security of the system. The analysis is based suing the n-1 rule which is performed in advanced and applying the results immediately after the detected contingency. Each analysis has its associated strategies consisting with the corresponding amount of load to be shed at a fixed number of controlled nodes. The optimisation however is evaluated based on the steady state values of angle, voltage and active power (generator and load). Load shedding based on static optimisation performs load flow to calculate the initial P, V for all the nodes in the system. Then the method performs a transient simulation assessment to ensure the system is stable against angle and voltage. Followed by an approach to the minimisation of a function in presence of equality and inequality constrains consist in incorpora ting the inequalities in the cost function by adopting the penalty factor method and treating the whole problem as a minimisation in presence of the sole equality constrains by the use of Lagrange multipliers. This method has been used for synchronous generators in transmission systems. However in distribution networks because of the diversity of the generators and their ride through capability this approach could result in conditions where optimised solutions do not meet the requirements as shown in Figure 1 -2 [0]. Figure 1à ¢Ã¢â€š ¬Ã¢â‚¬Ëœ2: Ride through capability of Generating Unit, DC Converter or Power Park Modules. Explanation of graph required. Each Generating Unit, DC Converter or Power Park Module shall remain transiently stable and connected to the system without tripping. However for small generating units connected in the distribution network their transient behaviour could be as shown in Figure 1 -2 b and c where local protection and circuit breaker operation of generators or sensitive equipment will be disconnected after such a response. Similar to the voltage is for the frequency range. Therefore the load flow with corrective control for angle and voltage stability approach for the load shedding optimisation is not appropriate for distribution networks. In [0] and [0] describe of a method implemented in distribution networks where not only the amount of load shedding is optimised but also the time for the disconnection. The current trend is to apply the corrective measures as soon as possible or delayed for the sake of event discrimination. The study and results however show that when the corrective action is applied at the optimal time increased damping and enhanced response are observed. summary The use of load shedding as a tool to keep the network stable has been constantly evolving, and different approaches have been formulated. Relaying schemes like underfrequency and ROCOF [0] [0] are some examples of the mechanisms implemented to trigger a load shedding event. Typical load shedding schemes based on predefined threshold set points is quick, simple and reliable measure against system disturbance. When the frequency of the system reaches a specified threshold value, a time delay is inserted prior to the shedding action in order to avoid overshedding and assist the coordination of the next stage of load shedding action. This technique however when adopted for the islanded operation of small distribution networks would have several disadvantages. Too few frequency levels could lead to overshedding, but on the other hand, time delays between stages could add up and may not allow for enough load to be shed in time to re-establish nominal frequency. The implementation of ROCOF techniques mitigates some of these problems. The ROCOF value calculation is an immediate indicator of the power imbalance; but for the distribution network the variation of the DG units operation would make this measurement unreliable. Also the average ROCOF calculation may take too long and eventually make the load shedding method slow in operation. Even if accurate measure of the islanded distribution network ROCOF valu

Camaro Essay -- Automobiles Chevrolet Camaros Essays

Camaro The name â€Å"Camaro† came from a French word for friend. The decision on the name came down to the last minute, with most of the world sure the car would be named, â€Å"The Panther.† Although the strange name had to be explained to the public, Camaro fit in with other Chevy names- Corvette, Chevelle, Chevy 2, and Corvair. The main reason the Camaro was introduced was because of the huge success of the Ford Mustang. The Camaro was roughly the same size as the Mustang, a little wider and based more on performance. The Camaro is one of the last remaining muscle cars still in production today. It is only fitting that buyers still expect maximum performance from their Camaros. It is that expectation that has kept the Camaro alive for all these years, while many other cars have faded away, lost in memory. The Mustang GT only only offered the 289- cubic inch or an 390- cubic inch V8 in 1967. The Camaro rolled out with 302, 327, 350, and 396 cubic inch V8’s (Camaro 14) The Camaro’s style was much smoother as well. The introduction of the Camaro threw pony car development into a frenzy. Before the Camaro, the Mustang and Barracuda were not quite considered full muscle cars. Most serious performance enthusiasts still opted for intermediate sized GTO’s or the Chevelle Super Sports (SS). The Camaro changed the image of those sport coupes. (Camaros, Eric Ethan) The Z28 and the stout SS-396 were more than just a stylish ride. Under the hood Camaros were well respected. Such respect helped establish the Camaro as the premier high-performance pony car. Camaro sales increased each year form 1967-1969. To this day, these Camaros are the favorite among enthusiasts. The Camaro brings a bad-boy image to the street and the track. The car has always been based on racing even when the Camaro was not officially involved. â€Å"It’s at home drag racing, and racing away from convenience stores after hold-ups. Because of this, media has given the Camaro a bad boy reputation.†(American Muscle Cars, 47) 1969 saw several noteworthy changes to the Camaro. The grill became deeper set, the taillamps were longer and thinner and broken into three segments. A heavy "eye-brow" crease was added on the both sides of the car extending from the front wheel well to the rear wheel well. A matching crease went from the rear wheel well to the rear quarter panel. Endura rubbe... ...white was perhaps better suited to the older cars, but the look was still striking. Chevrolet even revived the interior with 30th anniversary logos. White wheels added to the effect. 1998 was a big year for the Camaro. It received a major refreshening with body upgrades including a new front fascia, a new hood, composite reflector headlamps, and new fenders. The 1998 model also received chassis upgrades, a new 4-wheel disc brake system and a new anti-lock brake system (ABS). But the biggest upgrade was the all new LS1 V8 engine for the Camaro Z28. This new engine produces 335 horsepower. That’s more than twice the standard horsepower offered in the 1982 Z28, to shine a little perspective on the state of modern high-performance. Although most Camaros sold through the years have not been performance models, it is still the image and reputation of the various Super Sports, Z28’s, Pace Cars, and IROC-Zs that have defined the Camaro and kept the car in the public eye. While other car fashions have changed, Camaro buyers still want powerful V8s driving the real wheels, preferably with a manual transmission between the two. Given the opportunity, they will buy performance.

Themes in Silas Marner :: Silas Marner Essays

Themes in Silas Marner Silas Marner, written by George Eliot in 1861, attempts to prove that love of others is ultimately more fulfilling than love of money. This theme shows throughout the book, though the manner in which it is revealed leaves a bit to be desired. Often Silas Marner is criticized for being such a simple, unrealistic story. It does seem odd that after fifteen years of almost solitary confinement, Silas can trade his love of gold for his love of a daughter overnight. Despite Eliot’s attempt to portray Silas’s reawakening to society as a slow transition, the reader interprets his change of heart as a direct and immediate result of Eppie’s arrival. Despite these flaws in the story, the overall theme that man cannot live in a vacuum is portrayed by Eliot very well. Though Silas finds some satisfaction in his tenacious weaving and hoarding of gold, he only discovers true happiness after he dedicates himself to inter-personal relationships. Though his exile from Lantern Yard proves devastating to his self confidence and trust in others and God, fifteen years later Silas makes a full recovery, adopting Eppie to replace his love of money with love of a daughter. The fact that Lantern Yard has disappeared years later when Silas and Eppie go to visit it suggests that this town is no longer dear to Silas. In fact the removal of the town serves as a metaphor for Silas’s ability to find happiness outside his past. Also, near the conclusion of the story, the "fits" of Silas seem to have subsided. This makes sense because since the bachelor weaver has recovered and Eppie has opened his eyes to the reality of the world again, his soul is no longer separate from his body. While before, his soul was exiled and held in a purgatory of sorts before he found Eppie, now his spirit is alive and well, living in the present. Yet he still has relapses, suggesting that the fifteen years of self-torture have left permanent scars on his troubled soul. One lesser theme of the book is in regards to the Cass family. Eliot, through her portrayal of Godfrey and Dunstan as wealthy, selfish scoundrels who try to use one another and others to their personal advantage, asserts that the upper class has damaged society. While the Cass family, thinking that their wealth gives them undue privilege and rights to property (Godfrey’s attempt to seize Eppie from Silas), seems incredibly egocentric, Silas, representing the lower class, is seen as a humble victim of class bias.