Analysis - I have written my article about cloning Essay Example for Free

Analysis I have written my article about cloning Essay I have written my article about cloning. The opinions I have used in it are a highly exaggerated depiction of extremist views. I have shown, how ridiculous and outrageous these views are by overstressing every point and going to immense extremities, such as the master race and the worker race, these are so severe that the worker race would even be kept underground. I used pictures in my writing to make it easier for people to visualize the images that I am talking about because then they will be able to understand my ideas better. I have inserted a picture of Britney Spears, as she is a well-known, famous star, that many people like, or would like to be. The reason that I have included this particular image is because many people long to live like these stars and by using the image I am implying that if we introduce cloning and the so- called master race then everyone will be able to live like this. Many people believe that she is a perfect human being and this is the idea that I am trying to convey with the master race, that after using the system for a couple of decades, what will be left will be a, supposedly, perfect human race, which for many people the picture used illustrates perfectly. If I had room for more pictures on the page I would have used a picture of another stereotypical perfect male star to appeal to both sexes, but I wanted the article to look professional so I tried to keep the number of pictures too minimum. The picture will also encourage people to read the article because if they have turned over the page and they then see the picture of Britney. If they are an admirer, then they will most probably turn back to the start of the article to read it the whole way through. The reason that the picture has been repeated three times is because it shows what could be achieved by cloning, not just one, allegedly, flawless human being but as many as wanted, a whole race of them even. The repetition shows the main process of cloning as well, making an identical copy of something/ someone. I also use pictures of Morlocks from the film of the book The Time Machine by H. G Wells. The book and the films are set far into the future, this is also a little indication of the fact that this is could really happen in the future. These creatures were humans but as time has passed they started to live underground as they were using all of the earths resources, that is the main reason that I am using this picture to show what the, as I have called them in my article, worker race, would be like as my extreme plan is to have them working day and night, underground to provide the master race with everything they need. The reason that I have used such a ghastly picture is because I want it shock the reader, it will also draw attention to the article. The workers wont be good-looking, as they will never of had sunlight on their skin and never of had any of the beauty products and treatments we take for granted so the picture is an accurate representation of what they would actually look like. The contrast between the purportedly picture perfect Britney and the hideous, unsightly Morlock should make people start to think that they would much rather be with the master race rather than the workers. There is also the idea that this is what the human race has become as it has evolved and that cloning could save us from this atrocious fate and instead bring us to the attractive future that the master race offers. Two of the pictures are in black and white, these are the pictures of the worker race, these are in black and white to give a feel of darkness to the pictures and to imply that this is the sort of life they would have, never seeing any colour, whereas the picture of the master race is brightly coloured and shows an image that people feel drawn to look at unlike the pictures of the Morlocks and the ants. This means that the contrast is even more noticeable between the two sets of pictures. I have used the layout of having the pictures cutting into the writing, so that you cant help looking at the pictures while you are reading, helping the readers to picture the ideas I am putting into their heads, I have also put captions underneath the pictures to show what the pictures are of and how they relate to the topic of the article. The pictures are large and stand out from the page causing them to catch the readers eye whilst they are flicking through the paper, meaning that they read the article. I have used a strong title, Hitler Was Right, to fascinate the reader even before they have started reading the article. Including a strong political figure compels people to read the article as it looks like it could be an article of great importance. They will straight away wonder what the article could be about, causing suspense that will keep them reading until the very end of the article when they will realize that I was simply, apparently, agreeing with one very simple part of Hitlers range of ideas, that the world would be a better place if just one master race was to occupy it. This title has been written in Times New Roman and is in font size 36, I have done this so that the title stands out from all of the other things on the page. People wont be able to help noticing the title and this will generate interest in the article. The main body of the writing is in a quite large text; this is because I want it to stand out and not to be too small. The effect of this is that the article will not look as much of a difficult task to read, encouraging more people to read it. The prologue to the article is written in bold writing slightly bigger than in the main body of the text, this is so that this will stand out just a little bit more and people will read it before they read the main article. The writing in this prologue is encouraging people to read the main article. By ending it with a question the question is: why not? It makes people read on, as they want to find out the answer to this question, Straight away, in this first prologue I have shown my opinion, that I agree with cloning and all of the brilliant ideas that come along with it, this means that people will be under no disillusion while they are reading the article.

The Ferranti Effect

The Ferranti Effect As the length of the line increases specially in extra high voltage (EHV) lines, beyond 200km, we observe a phenomenon called Ferranti Effect in no load or low load conditions. This is due to the fact that as the line length increases the capacitance of the line increases, and the shunt capacitance generates the reactive power in the line. Since there is no load or low load to consume that excessive power, this results in excessive reactive power in the line and hence the receiving end voltage gets higher than the sending end voltage. This rise in voltage may well go beyond the operative ratings of the terminal and hence might give rise to many cascading events damaging the equipments. The continuous increase of the voltage of transmission, line length and number of sub-conductors per bundle has emphasized the importance of the excessive line MVAR in EHV systems as well as associated voltage and reactive controls. During the line charging volt-amperes of the line which have exceeded the inductive VARs consumed and operation at light loads, there is an undesirable voltage rises along the line. This voltage rise in turn demands a much higher insulation level, which poses a great problem. Moreover, if the insulation against these over-voltages were to be provided in the system, then the cost of the line becomes enormous. To overcome this phenomenon, shunt reactors are required to be installed at optimized location to absorb the excessive reactive power. Though this solution has a financial cost, but this is inevitable, since the load is a random variable and the generation of the power cannot be exactly planned for sudden tripping off of the loads. Aims and objectives: The aim of this thesis project is to investigate the Ferranti effect for long length transmission lines using PowerWorld simulations on a radial system. The following are the key objectives covered in this project. Impact by varying Line lengths: Investigate the system behavior regarding Ferranti effect with different transmission line lengths. This was done by investigating the profile of the effect for long length lines and hence distributed models were considered for this analysis. 2-Impact by varying loading levels: Since Ferranti effect is the phenomenon where receiving end voltage (Loads) is lower than sending end, it was important to look into the loading factor by varying the loading levels for different line lengths. 3- Investigation for optimum load levels to avoid effect: A series of experiments were done to find the minimum values of load required for varied line lengths in order to avoid Ferranti Effect and to contain the terminal voltage near 1p.u. 4- Minimum ratings for reactors for compensation: With a varied number of simulations and experiments, the minimum ratings of required reactors have been realized in order to maintain optimized terminal ratings at receiving end. Scope of thesis: This thesis will commence with an overview of the problems encountered with EHV long transmission line. This would be followed up by a literature review that covers the research of useful background theories. The result from the performed simulations will be discussed in detail. Finally, some recommendation for future works in this area of research. Chapter 2. INTRODUCTION TO TXN LINES: The electric lines which are used to carry electric waves are called transmission lines. The transmission line parameters like inductance and capacitance are not separable unlike the lumped circuits. The transmission parameters are distributed all along the length of the transmission line. Hence the method of analyzing the transmission lines is different from analyzing the lumped circuits. In the analysis of the transmission line, only steady state currents and voltages are concerned. The analysis includes the measurement of current and voltages at any length of the line, when a known voltage is applied at one end of the transmission line. The end at which the voltages are applied is called sending end and the end at which the signals are received is called receiving end of the transmission line. 2.1-transmission line parameters: For the analysis and design of transmission lines, it is important to have knowledge of electric circuit parameters, associated with the transmission lines. Various electric parameters associated with the transmission lines are as below, 1-Resistance: Depending upon the cross sectional area of the conductors, the transmission lines has resistance associated with them. The resistance is uniformly distributed all along the transmission line. Its total value depends upon the total length of the transmission line. Hence its value is given per unit length of the transmission line. It is denoted as R and is given in ohms per unit length. 2- Inductance: When the conductors carry the current, the magnetic flux is produced around the conductors. It depends upon the magnitude of the current flowing throw the conductors. The flux linkages per ampere of the current, gives rise to the effect called inductance of the transmission line. It is also distributed all along the length of the transmission line. It is denoted as L and measured in Henry per unit length of the transmission line. 3- Capacitance: The transmission lines consist of two parallel conductors or single line w.r.t earth separated by dielectric like air. Such conductors separated by an insulating dielectric produce a capacitive effect. Due to this, there exists a capacitance associated with the transmission line which is also distributed all along the length of the conductor. It is denoted as C and measured in Farads per unit length of the transmission line. 4- Conductance: The dielectric between the conductors is not perfect. Hence a very small amount of current flows through the dielectric called displacement current. This is nothing but leakage current and this gives rise to the leakage conductance associated with the transmission line. It exists between the conductors and is distributed all along the transmission line. It is denoted as G and measured as mho per unit length of the line. Thus the four important parameters of the transmission line are R, L, C and G. as the current flows from one conductor and complete the path through other conductor, the resistance of both the wires is included when specifying the resistance per unit length of the line. These line parameters are constant and are called the primary constants of the transmission line. Revisit snaps(4-16(1)) 2.2-performance equation of long transmission line: kundar book We can analyze the performance of the line on per phase basis. The relationship between current and voltage along the one phase of the line in terms of distributed parameters can be seen in the FIG below = series impedance per unit length/phase. = shunt admittance per unit length/phase. = length of the line. The voltages and current in the figure are the phasors representing sinusoidal time varying quantities. For a differential section of the line of length at a distance from receiving end, the differential voltage can be given as . hence (2.1) The differential current flowing through shunt admittance can be given as Similarly (2.2) Differentiating eq 1 and 2 yeilds (2.3) and (2.4) Now for the general equation for voltage and current at distance x from receiving end, if the receiving end voltage and current are known, can be given as (2.5) (2.6) Whereas this is called characteristic impedance. and = = this is called propagation constant. The constant and are complex quantities. The real part of propagation constant () is called the attenuation constant , while the imaginary part is called the phase constant . Now the first term in eq.5 increase in magnitude and advances in phase as the distance increases. This term is called incident voltage. While the second term in eq.5 decreases in magnitude and distorts in phase from receiving end towards sending end, this term is called reflected voltage. At any point along the line the voltage is the sum of incident and reflected voltage. The same is true for eq.6 . If a line is terminated at its characteristic impedance , then there is no reflected voltage and the line is called a flat line or infinite line. For a typical power line, G is practically zero and R Zc = = (2.7) = = (2.8) If losses are completely neglected the is a real number and is an imaginary number. Similarly for a lossless line eq.5 and 6 can be simplified as (2.9) (2.10) The voltage and current vary harmonically along the line length. A full cycle of voltage and current along the line length corresponds to 2 radians. If is the phase shift in radians per meter, the wavelength in meters is (2.11) 2.3-Equivalent circuit representation of long transmission line: A line with length more than 160km is considered a long transmission line and the parameters are assumed to be distributed uniformly along the line as a result of which the currents and voltages would vary from point to point. Let us consider the figure below series impedance per unit length shunt admittance per unit length length of the line total series impedance total shunt admittance The elemental equivalent of the above figure can be redrawn as follows. For analysis purpose we take receiving end as reference for measuring the distance. Assume we have an elemental length at the distance of x from the receiving end. If the voltage and current at distance x are and, so at the distance of so the voltage and current becomes + and + respectively. 2.12 By manipulating above equations Similarly 2.13 With above can be written as 2.14 And 2.15 By differentiating eq 2.14 2.16 The solution of eq 2.16 is 2.17 From eq 2.14 and 2.16 2.18 Where is the characteristic impedance and is the propagation constant. Eq 2.17 and 2.18 can be written as 2.19 2.20 If receiving end voltage and current are known then Substituting above values in eq 8 and 9 Again substituting values of A and B in eq 2.19 and 2.20 2.21 2.22 Since and are the voltage and current at any point distance x from receiving end as evident from expression and (magnitude and phase) are functions of distance , receiving end voltage and receiving end current , which means that they vary as we move from receiving end towards sending end. Now the quantities and are complex For a lossless line; When dealing with high frequencies or surges normally the losses are neglected and the characteristic impedance becomes surge impedance. Due to large capacitance and lower inductance in the cables the surge impedance values can be very low. For = = the real part of propagation constant () is called the attenuation constant , while the imaginary part is called the phase constant . Eq 2.11 can be written as 2.23 The first term in the above expression is called incident voltage wave and its value increases as x is increased. Since receiving end is our reference end and as x increases the value of voltage increases meaning the magnitude of voltage decreases as it travel towards the receiving end. Thats why the first part of expression is called incident voltage and the second is called reflected voltage for the similar reason. Same can be said about the current expression as well. Voltage and current expressions can be rearranged as below 2.24 And for current 2.25 For , and 2.26 2.27 The above derived quantities are related by the general equations 2.28 2.29 Where are such that Compairing the coefficients of above expression with eq 2.28 and 2.29 From this it is clear that 2.3.1-Equivalent representation: Considering the same two terminal condition with sending and receiving end voltage and current, the network can be represented as figure below. From the above network we can derive the following expressions 2.30 2.31 By comparing eq 2.30 and 2.31 with eq 2.26 and 2.27 2.32 2.33 2.34 2.35 From eq 2.33 we can derive We can conclude from this that to get the series impedance should be multiplied with . Now to get the shunt arm of equivalent circuit we substitute in eq 2.32 Here is the total shunt admittance. So to get the total shunt arm of the equivalent th eshunt arm of the nominal should be multiplied with , so the equivalent circuit can be drawn as below. 2.3.2 Equivalent representation of long line: A similar derivation of equivalent circuit can be, the equivalent circuit can be represented as Figure below. By analyzing the circuit following expression can be extracted 2.36 2.37 Comparing eq 2.36, 2.37 with 2.26, 2.27. 2.38 2.39 2.40 2.41 Now using eq 2.40 for shunt branch of equivalent circuit we get, Therefore its evident that to get the shunt branch of equivalent circuit, we have to multiply with the shunt branch of nominal circuit. For series impedance eq 2.40 is substituted in eq 2.38, which gives So here we get the factor for multiplication with nominal circuit to get equivalent circuit impedance. And the resultant circuit can be drawn as figure below. 2.4-Fundamental requirements in ac power transmission: Bulk transmission of electrical power by ac in possible only if the following two fundamental requirements are satisfied. Major synchronous machines must remain stable in synchronism: The major synchronous machines in a transmission system are the generators which are incapable of operating usefully other than in synchronism with all the others. And this also is the fundamental of stability. Voltages must be kept near to their rated values: The second main requirement in ac transmission is the maintenance of correct voltage levels. Power systems are not inherently tolerant of abnormal voltages even for short periods. Undervoltage: this is generally associated with heavy loading and/or shortage of generation, causes degradation in the performance of loads. In heavy loaded systems, undervoltage may be an indication that the load is approaching the steady state stability limit. Sudden undervoltages can result from the connection of very large loads. Over voltages: this is a dangerous condition because of the risk of flashover or the breakdown of insulation. Over voltages arise from several causes. The reduction of load during certain parts of the daily load cycle causes a gradual voltage rise. Uncontrolled, this overvoltage would shorten the useful life of insulation even if the breakdown level were not reached. Sudden overvoltage can result from the disconnection of loads or other equipment, while overvoltages of extreme rapidly and severity can be caused by the line switching operation, faults and lightning. In the long transmission line this would limit the power transfer and the transmission distance if no compensating measures were taken. Chapter 3 compensated/uncompensated lines 3.1-Charging current in lines: Despite being able to avoid wire resistance through the use of superconductors in this thought experiment, we cannot eliminate capacitance along the wires lengths. Any pair of conductors separated by an insulating medium creates capacitance between those conductors: (Figure ) Voltage applied between two conductors creates an electric field between those conductors. Energy is stored in this electric field, and this storage of energy results in an opposition to change in voltage. The reaction of a capacitance against changes in voltage is described by the equation i = C(de/dt), which tells us that current will be drawn proportional to the voltages rate of change over time. Thus, when the switch is closed, the capacitance between conductors will react against the sudden voltage increase by charging up and drawing current from the source. According to the equation, an instant rise in applied voltage (as produced by perfect switch closure) gives rise to an infinite charging current. However, the current drawn by a pair of parallel wires will not be infinite, because there exists series impedance along the wires due to inductance. (Figure below) Remember that current through any conductor develops a magnetic field of proportional magnitude. Energy is stored in this magnetic field, (Figure below) and this storage of energy results in an opposition to change in current. Each wire develops a magnetic field as it carries charging current for the capacitance between the wires, and in so doing drops voltage according to the inductance equation e = L(di/dt). This voltage drop limits the voltage rate-of-change across the distributed capacitance, preventing the current from ever reaching an infinite magnitude: Equivalent circuit showing stray capacitance and inductance. The effect of capacitance of an overhead transmission line above 160km long is taken into consideration for all calculations. The effect of the line capacitance is to produce a current called charging current. This current will be in quadrate of the applied voltage. It flows through the line even if the receiving end is open-circuited. The charging current of the open circuit line is referred to as the amount of current flowing into the line from sending end to receiving end where there is no load. In many cases, the total charging current of the line is determined by multiplying the total admittance of the line by the receiving end of the voltage. This would be correct if the entire length of line has the same voltage as that of receiving end voltage. However this method of finding the charging current is sufficiently accurate for most lines. The actual value of the charging current will decrease uniformly from its maximum value at sending end to the minimum value at receiving end. Due to the charging current, there will be power loss in the line even the line is open circuited. 3.2-Surge Impedance Loading (sil pdf) As power flows along a transmission line, there is an electrical phase shift, which increases with distance and with power flow. As this phase shift increases, the system in which the line is embedded can become increasingly unstable during electrical disturbances. Typically, for very long lines, the power flow must be limited to what is commonly called the Surge Impedance Loading (SIL) of the line. (dr) or SIL is defined as the amount of power delivered by a lossless transmission line when terminated by a load resistance equal to surge or characteristics impedance. Surge Impedance Loading is equal to the product of the end bus voltages divided by the characteristic impedance of the line. Since the characteristic impedance of various HV and EHV lines is not dissimilar, the SIL depends approximately on the square of system voltage. A transmission line loaded to its surge impedance loading: (i) Has no net reactive power flow into or out of the line, and (ii) Will have approximately a flat voltage profile along its length. (dr) with load at the receiving end equal to SIL. Volts (3.1) It is clear from the equation that voltage magnitude at any point along the transmission line is constant with the magnitude equal to the receiving end voltage. Also, at SIL the general expression for current can be rewritten as . Amperes (3.2) Using (3.1) and (3.2), the complex power flowing at any point along the transmission line can be calculated as. (3.3) Hence, the amount of real power flowing along a lossless transmission line loaded at SIL is constant as expected. Also, noticed that the reactive power flowing in the line is zero. This point is crucial in understanding the phenomenon called Ferranti effect. When the line is terminated at SIL the net reactive power needed to deliver the real power by keeping the voltage constant is zero. In other words, the reactive power internally produced by shunt capacitance is just sufficient to fulfill reactive power required. However, when the loading conditions change from SIL or moderate loading to light load to heavy load, there will be imbalance in reactive power required to transmit the real power. In the absence of devices to control and compensate for reactive power, situation could result in lack or surplus of reactive power. Hence, create a low or high voltage profile, respectively in the receiving end of the transmission line. Typically, stability limits may determine the maximum allowable power flow on lines that are more than 160 km in length. For very long lines, the power flow limitation may be less than the SIL as shown in Table 0-1. Stability limits on power flow can be as low as 20% of the line thermal limit. Typical stability limits as a function of system voltage are given in table below: 3.3-The uncompensated line on open circuit: tjmiller The lossless line that is energized by the generators at the sending end and is open circuited at the receiving end is described by following equation with . 3.4 And 3.5 Voltage and current at the sending end can be given as 3.6 3.7 and are in phase, which is in consistent , with the fact that there is no power transfer. The phasor diagram shown in the figure. The voltage and current profiles in equation 1 and 2 are more conveniently expressed in terms of . 3.8 Phasor diagram of uncompensated line on open-circuit Voltage and current profile at no load condition. The general form of these profiles shown in fig 3.5 above. For a line 300km in the length at 50Hz, 3600 60 per 100km, so à °Ã‚ Ã…“ ½=6*3=180. Then and based on the SIL. The voltage rise on open circuit is called Ferranti Effect. Although the voltage rise of 5% seems small, the charging current is appreciable and in such a line it must all be supplied by the generator, which is forced to run at leading power factor, for which it must be underexcited. The reactive power absorption capability of a synchronous machine is limited for two main reasons The heating of the ends of the stator core increases during the under excited operation. The reduced field currents results in reduced internal emf of the machine and this weakens the stability. Note that a line for which à °Ã‚ Ã…“ ½=à °Ã‚ Ã¢â‚¬ ºÃ‚ ½Ãƒ °Ã‚ Ã¢â‚¬ ºÃ‚ ¼=à °Ã‚ Ã…“†¹/2 has a length of ÃŽÂ »/4 (one quarter length wavelength, i.e, 1500km at 50Hz) producing an infinite voltage rise. Operation of any line approaching this length is completely impractical without some means of compensation. In case of the sudden open-circuit of the line at the receiving end, the sending end voltage tends to rise immediately to open-circuit voltage of the sending end generators, which exceeds the terminal voltage by approximately the voltage drop due to the prior current flowing in their short circuit reactances. 3.4-Compensated transmission lines: Reactive power compensation means the application of reactive devices To produce a substantially flat voltage profile at all levels of power transmission. To improve stability by increasing the maximum transmissible power, and/or To supply the reactive power requirements in the most economical way. Ideally the compensation would modify the surge impedance by modifying the capacitive and/or inductive reactances of the line, so as to produce a virtual surge impedance loading that was always equal to the actual power being transmitted. Yet this is not sufficient to ensure the stability of the transmission, which depends also on the electrical line length. The electrical length can itself be modified by the compensation to have a virtual à °Ã‚ Ã…“ ½shorter than the uncompensated value, resulting in an increase in the steady state stability limit This consideration suggests two broad classification scheme, Surge impedance compensation and line length compensation. Line length compensation in particular is associated with series capacitors used in long distance transmission. Another compensation is called compensation by sectioning, which is achieved by connecting constant voltage compensators at intervals along the line. The maximum transmissible power is that of the weakest section but since this is necessarily shorter than the whole line, an increase in maximum power and , therefore , in stability can expected. 3.4.1-Passive and active compensators: Passive compensators include shunt reactors and capacitors and series capacitors. They modify the inductance and capacitance of the line. Apart from the switching, they are uncontrolled and incapable of continuous variation. For example, shunt reactors are used to compensate the line capacitance to limit voltage rise at the light load or no load condition. They increase the virtual surge impedance and reduce the virtual natural load Shunt capacitor may be used to augment the capacitance of the line under heavy loading. They generate reactive power which tend to boost the voltage. They reduce the virtual surge impedance and increase . Series capacitors are used for line length compensation. A measure of surge impedance compensation may be necessary in conjunction with series capacitors, and this may be provided by shunt reactors or by a dynamic compensator. Active compensators are usually shunt connected devices which have the property of tending to maintain a substantially constant voltage at their terminals. They do this by generating or absorbing precisely the required amount of corrective reactive power in response to any small variation of voltage at their point of connection. They are usually capable of continuous variation and rapid response. Active compensators may be applied either for surge impedance compensation or for compensation by sectioning. In compensation they are capable of all the functions performed by fixed shunt reactors and capacitors and have additional advantages of continuous variability with rapid response. Compensation by sectioning is fundamentally different in that it is possible only with active compensators, which must be capable of virtually immediate response to the smallest variation in power transmission or voltage. The table below summarizes the classification of the main type of compensators according to their usual functions. 3.4.2-Shunt compensation: Shunt reactors are used to limit the voltage rise at the light load or no load conditions. On long transmission they may be distributed at intermediate substations in shown in figure below voltage and current profile of shunt compensated system at no load. Consider the simple circuit above in figure, it has a single shunt reactor of reactance at the receiving end and a pure voltage source at the sending end. The receiving end voltage can be given as 3.9 3.10 Equation 7 shows that and are in phase, in keeping with the fact that the real power is zero. For receiving end voltage to be equal to sending end voltage , must be given by 3.11 The sending end current can be given as 3.12 using equation 3.9 and 3.11 3.13 Since , this means that the generator at the sending end behaves exactly like the shunt reactor at the receiving end in that both absorb the same amount of reactive which is evident from equation below. 3.14 Chapter 4 Ferrenti effect 4.1 Ferranti effect: A long transmission line draws a substantial quantity of charging current. If such a line is open circuited or very lightly loaded at the receiving end, the voltage at receiving end may become greater than voltage at sending end. This is known as Ferranti Effect and is due to the voltage drop across the line inductance (due to charging current) being in phase with the sending end voltages. Therefore both capacitance and inductance is responsible to produce this phenomenon. Another way of explaining Ferranti effect is based on net reactive power flow in the line. It is known that if the net reactive power generated in lie is more than the reactive power absorbed, the voltage at that point in the line becomes higher than the normal value and vice versa. The inductive reactance behaves like a sink in the line whereas the shunt capacitance generates the reactive power. If the line loading corresponds to the surge impedance loading, the voltage is same everywhere as reactive power absorbed in the line is equal to the reactive power generated. If the loading is less than SIL, generated power is more than generated power absorbed, therefore, the receiving end voltage is higher than sending end voltage. The capacitance (and charging current) is negligible in short line but significant in medium line and appreciable in long line. Therefore this phenomenon occurs in medium and long lines. Represent line by equivalent model. And the vector diagram can be given as OM = receiving end voltage Vr OC = Current drawn by capacitance = Ic MN = Resistance drop NP = Inductive reactance drop Therefore; OP = Sending end voltage at no load and is less than receiving end voltage (Vr) Since, resistance is small compared to reactance; resistance can be neglected in calculating Ferranti effect. From model, For open circuit, no load, There fore Or Or By neglecting resistance The quantity is constant in all line and is equal to velocity of propagation of electromagnetic waves (= 3 ÃÆ'- 102 km/sec) By substituting the values in the above derived equation And And finally From the above equation So or Receiving end voltage is greater than sending end voltage and this effect is called Ferranti Effect . 5.1, fig 4.10,4.6,4.4,4.2,4.1,3.5,3.4,2.1 Chapter 5 results and discussion Results and discussions: To simulate for my analysis, a radial system in the following figure was modeled as test system. Practical industrial data was acquired from Queensland Electric Commission which follows the Australian standard for conductors and enforces the transmission and distribution company to follow the standards. This acquisition was important to incorporate for more realistic analysis and observe the phenomenon as it is appeared in the real life transmission systems. Conductor types for the simulation were chosen from the provided list

How People Interact With Search Engines

How People Interact With Search Engines A search engine is a web-based tool that enables users to locate information on the World Wide Web. Popular examples of search engines are Google, Yahoo!, and MSN Search. Search engines utilize automated software applications (referred to as robots, bots, or spiders) that travel along the Web, following links from page to page, site to site. The information gathered by the spiders is used to create a searchable index of the Web. When people use the term search engine in relation to the Web, they are usually referring to the actual search forms that searches through databases of HTML documents, initially gathered by a robot. There are basically three types of search engines: Those that are powered by robots (called crawlers; ants or spiders) and those that are powered by human submissions; and those that are a hybrid of the two. HOW DO SEARCH ENGINES WORK? Every search engine uses different complex mathematical formulas to generate search results. The results for a specific query are then displayed on the SERP. Search engine algorithms take the key elements of a web page, including the page title, content and keyword density, and come up with a ranking for where to place the results on the pages. Each search engines algorithm is unique, so a top ranking on Yahoo! does not only a short period before the search engines developers become wise to the tactics and change their algorithm. More likely, sites using these tricks will be labeled as spam by the search engines and their rankings will plummet. animation mean nothing to search engines, but the actual text on your pages does. It is difficult to build a Flash site that is as friendly to search engines; as a result, Flash sites will tend not to rank as high as sites developed with well coded HTML and CSS (Cascading Style Sheets a complex mechanism for adding styles to website pages above and beyond regular HTML). If the terms you want to be found by do not appear in the text of your website, it will be very difficult for your website to yield high placement in the SERPs. Crawler-based search engines are those that use automated software agents (called crawlers) that visit a Web site, read the information on the actual site, read the sites meta tags and also follow the links that the site connects to performing indexing on all linked Web sites as well. The crawler returns all that information back to a central depository, where the data is indexed. The crawler will periodically return to the sites to check for any information that has changed. The frequency with which this happens is determined by the administrators of the search engine. Human-powered search engines rely on humans to submit information that is subsequently indexed and catalogued. Only information that is submitted is put into the index. In both cases, when you query a search engine to locate information, youre actually searching through the index that the search engine has created -you are not actually searching the Web. These indices are giant databases of information that is collected and stored and subsequently searched. This explains why sometimes a search on a commercial search guarantee a prominent ranking on Google, and vice versa. To make things more complicated, the algorithms used by search engines are not only closely guarded secrets, they are also constantly undergoing modification and revision. This means that the criteria to best optimize a site with must be surmised through observation, as well as trial and error and not just once, but continuously. Gimmicks less reputable SEO firms tout as the answer to better site rankings may work at best for engine, such as Yahoo! or Google, will return results that are, in fact, dead links. Since the search results are based on the index, if the index hasnt been updated since a Web page became invalid the search engine treats the page as still an active link even though it no longer is. It will remain that way until the index is updated. So why will the same search on different search engines produce different results? Part of the answer to that question is because not all indices are going to be exactly the same. It depends on what the spiders find or what the humans submitted. But more important, not every search engine uses the same algorithm to search through the indices. The algorithm is what the search engines use to determine the relevance of the information in the index to what the user is searching for. One of the elements that a search engine algorithm scans for is the frequency and location of keywords on a Web page. Those with higher frequency are typically considered more relevant. But search engine technology is becoming sophisticated in its attempt to discourage what is known keyword stuffing, or spamdexing. Another common element that algorithms analyze is the way that pages link to other pages in the Web. By analyzing how pages link to each other, an engine can both determine what a page is about (if the keywords of the linked pages are similar to the keywords on the original page) and whether that page is considered important and deserving of a boost in ranking. Just as the technology is becoming increasingly sophisticated to ignore keyword stuffing, it is also becoming more savvy to Web masters who build artificial links into their sites in order to build an artificial ranking. SEARCH ENGINE OPTIMIZATION Search engine optimization (SEO) is the process of affecting the visibility of a website or a webpage in a search engines natural or un-paid (organic) search engine results In general, the earlier (or higher ranked on the search results page), and more frequently a site appears in the search results list, the more visitors it will receive from the search engines users. SEO may target different kinds of search, including image search, local search video search, academic search news search and industry-specific vertical search engines engines. As an internet marketing strategy, SEO considers how search engines work, what people search for, the actual search terms or keywords typed into search engines and which search engines are preferred by their targeted audience. Optimizing a website may involve editing its content ,HTML and associated coding to both increase its relevance to specific keywords and to remove barriers to the indexing activities of search engines. Promoting a site to increase the number of back links or inbound links, is another SEO tactic. HOW PEOPLE INTERACT WITH SEARCH ENGINES We like to say Build for users, not search engines. When users have a bad experience at your site, when they cant accomplish a task or find what they were looking for, this often correlates with poor search engine performance. On the other hand, when users are happy with your website, a positive experience is created, both with the search engine and the site providing the information or result. What are users looking for? There are three types of search queries users generally perform: Do Transactional Queries Action queries such as buy a plane ticket or listen to a song. Know Informational Queries When a user seeks information, such as the name of the band or the best restaurant in New York City. Go Navigation Queries Search queries that seek a particular online destination, such as Facebook or the homepage of the NFL. When visitors type a query into a search box and land on your site, will they be satisfied with what they find? This is the primary question search engines try to figure out millions of times per day. The search engines primary responsibility is to serve relevant results to their users. It all starts with the words typed into a small box. KEYWORD RESEARCH It all begins with words typed into a search box. Keyword research is one of the most important, valuable, and high return activities in the search marketing field. Ranking for the right keywords can make or break your website. Through the detective work of puzzling out your markets keyword demand, you not only learn which terms and phrases to target with SEO, but also learn more about your customers as a whole. Its not always about getting visitors to your site, but about getting the right kind of visitors. The usefulness of this intelligence cannot be overstated with keyword research you can predict shifts in demand, respond to changing market conditions, and produce the products, services, and content that web searchers are already actively seeking. In the history of marketing, there has never been such a low barrier to entry in understanding the motivations of consumers in virtually every niche.

Living Through God: The Meaning of a Christian :: social issues

Living Through God: The Meaning of a Christian "Without God, the thinkers of the world will never grasp the meanings of life, origin and destiny†, so the strong spirited young woman remarks about life. Teenagers today appraise their lives through school, work, and friends. Often times, there is one type of teenager that displays a greater attitude, in which whom goes beyond the obvious by simply shining a little brighter. A courageous teen of determination, providing inspiration, possesses such positive attributes, gives reason to classify her by inspiring and strengthening the youth of today. On October 25, 1985, an individual, so concise, diminutive, or what seemed to be not much of great impact of this world, was born. Subsequently, becoming one that gives profound importance in the hearts of those she will touch. Arica Helaine Ingratta, a teenager of uniqueness in every way, persists by perceiving life by one entity, God. Initially, Arica procures from a family consisting of a younger brother, an older sister, a set of parents, one dog, two cats, and a hamster. Indeed, one may perceive this family to be a little unconventional; it is. Born and raised in Windsor, Ontario, Arica grew up with a strong grasp on life from the very beginning. Her story entitles one to be unique, inspiring, and meaningful. â€Å"Arica Helaine†, derives from her father’s name, Ericolino, and Helen, the name of her mother. Her beginnings of education sets out at St. Gabriel’s catholic school where, in grade 4, she transferred schools to the Maranatha Christian Academy and later to First Lutheran Christian Academy where she developed a fundamental Christian basis. She was an intelligent, little princess that was often called â€Å"peanut†. An asset to her character is her genuine smile. Filled with energy and ambitions, she carries a strong spirit in whatever she does or is determined in becoming; so on to discover the meaning of life. Having acquired from a Christian family, she learns the meaning of God through her parents and school. While the world celebrated the coming of the New Year on December 31st of 1998, Arica was celebrating a rather different event. At a Christian concert, she became saved by accepting God into her life. She developed a personal relationship with God while continuing to live through Him. While many young teenagers were thriving about their girlfriends or boyfriends, their physical appearances, or the newest pop artist, Arica, by age 14, determined in becoming a youth Evangelist.

Analysis of The Tulse Luper Suitcases Trilogy Essay -- Peter Greenaway

History and time are considered to be cultural formations since a History cannot be detached from the culture in which it is produced and received. It is through culture that a historical sense is achieved and in fact, each culture experiences History in a different way leading us to the current perception of History as not being one, but many histories depending on the cultural groups involved. Historians have fought throughout the centuries on whether such thing as â€Å"objective History† can exist but in the end, even materialist historians will admit that the reality of History is so complicated and contradictory that no single version could possibly represent the truth; consequently different interpretations are inevitable. This is where Peter Greenaway comes in with his trilogy The Tulse Luper Suitcases in which the eponymous suitcases (of which there are 92) contain the collected memories of Tulse Luper, a manic collector of forgotten records and other evidence of the twentieth century. Devised as a trilogy, Peter Greenaway’s multimedia project concentrates on a period between 1928, the year in which the element uranium was discovered in Colorado, and 1989, the year when the Berlin wall came down and the Cold War came to an end. The two central events of the past one hundred years – the confrontation between East and West and the threat of atomic warfare – have left their mark on writer and realizer of projects Tulse Luper, who spends most of his time detained in some form of prison or another. Luper’s role is hard to define: his many encounters, the injuries he has sustained and fragments of sentences that surface from his memory, all combine to produce a complex weave or structure that includes both various periods in time a... ...aware of in his film, through the opposition between the reality of History on the one hand and the fiction of the Luper project on the other, the truth and stability of what really happened and the playful construction presented by Greenaway, the unincarnated omniscience of reality and the awkward contextualization provided by the Luper point-of-view. According to Greenaway, History does not exist in an absolute, unmediated form, but will always be filtered through the perceptions, interpretations and values of subjects as experiencers, filing instances, historians and readers. The event "as it was" thus can never be recovered in an absolute form and that is why â€Å"there is no such thing as History, [but] only historians† whose collective work only, can serve as a somewhat effective record of History.

Factors Influencing Unemployment Essay

According to economists, employment and unemployment results when the supply and demand for human resources or labour is out of balance. Supply and demand are influenced by a range of forces that are the result of the interaction of economic, structural and policy factors. Economic Factors Economic factors affect both the supply and demand sides of labour. Demand for goods and services stimulate production which, in turn, generates employment. The resulting demand for workers affects the supply side as more workers are attracted to a vibrant labour market. The market never reaches this ideal state of balance due to a number of factors. Business cycles  ¾ Agreement among economists is rare, but they do agree that market-driven economies move in cycles and it is during the dips that unemployment may result. The cause of cycles is not as clear, but it is generally agreed that it is a function of supply and demand. Industrial adjustment  ¾ Production may move from high wage countries to low wage countries, from old inefficient facilities to newer ones, and these leave a trail of unemployed workers. Not enough jobs  ¾ Shifts in the world economy affect job availability. Not enough jobs to go around can result from a declining manufacturing sector, a growing service sector, changing consumption patterns, technological developments, or third world competition. Hundreds of thousands of jobs have been lost in manufacturing and goods producing industries in Canada, while at the same time numerous jobs have been created in the technology and service sectors. Unfortunately, the creation of new jobs does not always make up for lost jobs, particularly when jobs overall move to low-wage countries. Structural factors Factors such as the aging of the population, labour force participation rates, migration patters, skills available/demanded, environmental regulations, technological change and the rate of job changes all the number of unemployed. A growing labour supply  ¾ Since 1981, Canada’s labour supply has grown more than anytime in its history. Women, persons with disabilities and Native peoples entered the labour force in growing numbers. Imbalance between skill supply and demand  ¾ This results in structural unemployment. People may not be able to take advantage of job opportunities because they lack the skills needed for the jobs available in their area. The matching of skills in demand with those available is a common and persistent cause of unemployment. Education and training  ¾ Companies continually complain that the literacy levels of the work force do not meet the skill needs of the economy. As Canada shifts to a more knowledge-based economy, the availability of jobs for those without high levels of education will shrink. Movement between jobs  ¾ Called frictional unemployment; this phenomenon simply refers to people who switch jobs. While they are between jobs, they are considered unemployed. Seasonal lay-off  ¾ People get laid off in seasonal occupations such as resource industries, construction, tourism and fisheries. Canada is particularly affected by this due to the nature of our economy. Cost of production and productivity  ¾ Low productivity may result from obsolete plant and equipment, high cost of labour per unit, high transportation costs, bad management, and high taxes. The value of the Canadian dollar relative to other currencies, particularly the US dollar, also has a major impact on the business costs and competitiveness. Technological changes  ¾ Increased automation may result in a decreased demand for labour. It can also result in skill redundancy where the original workers do not have the technological skills necessary in the new types of occupations. On the positive side, technological change can result in new products, new markets, or increased productivity. Internal migration  ¾ Rural to urban migration can increase unemployment until the moving people find jobs. Policy Factors Government policies continue to be used to affect the economic outcomes such as the rate of inflation, deficit levels, and international trade. This all affects employment levels. Interest rate and exchange rate policies  ¾ High interest rates to combat inflation increase the cost of doing business and increase the cost of financing the government deficits. This may lead to unemployment. The exchange rate policy of keeping the dollar artificially high may make Canadian products less competitive.

Florence Nightingale: Her life and dedication Essay

Florence Nightingale was born in Florence, Italy, May of 1820 and was named after this city. She was home schooled by her father, a highly educated man. Both Florence’s parents were wealthy and loved to travel. Although Florence’s family wanted her to marry, she knew from an early age that this was not for her. She had many callings from God, her first being when she was 17. In 1843, a man who tutored Florence asked her to marry him. She turned him down then and two years later, turned him down again. In 1842 Florence had her first thoughts about nursing. She became aware of hungry people in towns and villages and was aware of workhouses, hospitals and prisons that were completely overfilled. Florence became concerned for the poor and sick of villages that contained agriculture workers and weavers. She asked her mother for food, bedding and clothes and usually her mother would have helped her out, but not this time. Florence became unhappy with her life and felt that getting married like her mother wanted would not satisfy her. At the age of 24, she received another calling from God and decided to follow it. She felt she belonged in hospitals caring for the sick. When she asked her parents to learn more about nursing, they were not suitable with the idea and did not agree with it. In 1846, she decided that she might receive training in Germany at a hospital run by deacons and pastors where discipline and supervision was strictly enforced. Florence traveled to Kaiserwerth where she worked with the children in the hospital and attended an operation. Although there was no nurse training at kaiserwerth, she was happy to be helpful assistance to the patients. In March of 1854, England and France declared war on Russia known as the Crimean war. Sidney Herbert who was Secretary at War contacted Florence regarding her taking a party of nurses to the hospitals of the British Army. An article was written and published in October of 1854 stating that there was much anger that there were no sufficient medical preparations for the proper care of the wounded. Along with Florence, there were 14 other professional nurses and a number of people from religious institutions. When Florence returned from the Crimea, she was very much in demand, and received many social invitations, but refused them all. Although tired, she still wanted to continue with her work. She was concentrating on working for the reform of the Army Medical Services where she wanted to set up a Royal Commission. Although she had become tired and slightly ill, she still managed to work hard and turned all her attention to the Nightingale Training School. While she had to go back home to care for her parents and her sister, she still worked on the reconstruction of the Nightingale School. Her parent’s sickness became worse and the only way for her to keep control of the school was by writing letters or paying visits when she could. Nightingale was now left to enjoy her old age. She received an award which was a great honor because it was the first time it had been given to a woman. When people read about this great victory, she received many letters of congratulations and flowers. August of 1910, Florence Nightingale passed. She requested to not have a National funeral and to be buried alongside her parents at East Wellow. Florence Nightingale was an extremely important leader during the Crimean war and long after as well. What many might not know about this highly dedicated woman is there is an unusual part about her. Florence once noted â€Å"A small pet animal is often an excellent companion for the sick†¦Ã¢â‚¬  Since then, the medical profession has encouraged the use of animal companionship as a means to improve human health. Florence has been reported to carry a small owl with her that she named â€Å"Athena.† She carried the owl for years during the Crimean War. She also kept a pet tortoise in her pocket that she named â€Å"Jimmy† and took around with her when she traveled. This is weird because most people leave their pets at home, however Florence kept it with her for luck.