William Shakespeare Essays (909 words) - Counties Of England

William Shakespeare The history of William Shakespeare, poet and playwright, is anything but one free of controversy. There are several arguments challenging his very existence. Over the years, every aspect of his life has been studied and researched comprehensively. One of the most intriguing aspects of his life undoubtedly is his relationship with his wife and his various love affairs. This essay aims to highlight and analyze the environment surrounding his marriage and attempt to compare it with information presented in the screenplay. The various scholars who have involved themselves in bringing to life his past have come up with stirring evidence about his marriage. What is for certain is the fact that Shakespeare did marry a certain Anne Hathaway. "On November 28, 1582 the Bishop of Worcester issued the marriage bond for 'William Shagspere' and 'Ann Hathwey of Stratford' This was almost beyond doubt, Anne Hathaway, daughter of Richard Hathaway of Shottery" (1582 Marriage). This quote not only confirms this fact, but also gives us the most accurate known date of Shakespeare's wedding. However, some records have changed the whole story surrounding Shakespeare's marriage. Ivor Brown, in his book Shakespeare, traces the circumstances that led up to the marriage. William Shakespeare may not have married Anne Hathaway out of choice. "On November 27, 1582, an entry was made in the Episcopal register at Worcester. This set down the issue of a marriage license to William Shakespeare and Anne Whatley of Temple Grafton. On the next day, two yeomen of Stratford, Fulk Sandells and John Richardson, agreed to pay forty pounds should any legal consideration arise to prevent the marriage of William Shagspere and Anne Hathway of Worcester." (Brown 45) The first theory that can be proposed after reading the excerpt is that an error occurred in the recording of the wedding and was promptly taken care of the next day. But, what if Anne Whatley really did exist? After all, the excerpt does claim that the two Annes were from different towns. It isn't hard to tribute an affair to Shakespeare at all. Shakespeare didn't need looks to captivate a lady's heart. Over the years, he has captured the hearts of millions worldwide with his penmanship. Arguably, such a man could, at that young an age, have easily seduced several women with the magic of his words. And, even though he is some ten years older in the screenplay, Norman and Stoppard have done a brilliant job of portraying Will as an individual brimming with passion and lust in the screenplay. Though a mix up in names was commonplace of that time, it is unlikely that it took place in this instance. Hathaway and Whatley are wholly different names and Temple Grafton could certainly not have been penned down as Stratford. "Now however sleepy a clerk may have become during the course of his day's penmanship and its refreshment intervals, it is extremely unlikely that he would transliterate Temple Grafton into Stratford" (Brown 48). This bit of evidence may be the clue that suggests the possibility of Anne Whatley's existence. Had there been an Anne Whatley from Temple Grafton and an Anne Hathaway, from Stratford, it would give a juicy twist to the story of William Shakespeare, the lover! But, we can only speculate as to what the truth actually was. Perhaps, Shakespeare had intended to marry Whatley all the way and an irresistible Hathaway had suddenly walked into his life. Another possibility could be that the playwright was having an affair with both women at the same time and had made false promises to both. And, the reason he ended up marrying Hathaway was that she was three months pregnant. " . . . because the bride was some three months pregnant and there was reason for haste in concluding the marriage" (1582 Marriage). This corresponds with what Will tells Dr. Moth in the screenplay. So, we arrive at the conclusion that Shakespeare did not marry Anne Hathaway by choice. This would obviously imply that the relationship would not be a happy one and would in fact be short-lived. Hence, we return to Will's statement in the screenplay about the detached relationship between him and his wife. "WILL: Four years and a hundred miles away in Stratford. A cold bed too, since the twins were born. Banishment was a blessing" (12). This statement not only describes the emptiness between the couple, but also runs parallel with the possibility that Will indeed never wanted Hathaway as his wife. Another strong pillar supporting this theory is a statement from Shakespeare's will.

A Brief Explanation of Evolution

A Brief Explanation of Evolution The theory of evolution is a scientific theory that essentially states that species change over time. There are many different ways species change, but most of them can be described by the idea of natural selection. The theory of evolution through natural selection was the first scientific theory that put together evidence of change through time as well as a mechanism for how it happens. History of the Theory of Evolution The idea that traits are passed down from parents to offspring has been around since the ancient Greek philosophers time. In the middle 1700s, Carolus Linnaeus came up with his taxonomic naming system, which grouped like species together and implied there was an evolutionary connection between species within the same group. The late 1700s saw the first theories that species changed over time. Scientists like the Comte de Buffon and Charles Darwins grandfather, Erasmus Darwin, both proposed that species changed over time, but neither man could explain how or why they changed. They also kept their ideas under wraps due to how controversial the thoughts were compared to accepted religious views at the time. John Baptiste Lamarck, a student of the Comte de Buffon, was the first to publicly state species changed over time. However, part of his theory was incorrect. Lamarck proposed that acquired traits were passed down to offspring. Georges Cuvier was able to prove that part of the theory incorrect, but he also had evidence that there were once living species that had evolved and gone extinct. Cuvier believed in catastrophism, meaning these changes and extinctions in nature happened suddenly and violently. James Hutton and Charles Lyell countered Cuviers argument with the idea of uniformitarianism. This theory said changes happen slowly and accumulate over time. Darwin and Natural Selection Sometimes called survival of the fittest, natural selection was most famously explained by Charles Darwin in his book On the Origin of Species. In the book, Darwin proposed that individuals with traits most suitable to their environments lived long enough to reproduce and passed down those desirable traits to their offspring. If an individual had less than favorable traits, they would die and not pass on those traits. Over time, only the fittest traits of the species survived. Eventually, after enough time passed, these small adaptations would add up to create new species. These changes are precisely what makes us human.   Darwin was not the only person to come up with this idea at that time. Alfred Russel Wallace also had evidence and came to the same conclusions as Darwin around the same time. They collaborated for a short time and jointly presented their findings. Armed with evidence from all over the world due to their various travels, Darwin and Wallace received favorable responses in the scientific community about their ideas. The partnership ended when Darwin published his book. One very important part of the theory of evolution through natural selection is the understanding that individuals cannot evolve; they can only adapt to their environments. Those adaptations add up over time and, eventually, the entire species has evolved from what it was like earlier. This can lead to new species forming and sometimes extinction of older species. Evidence for Evolution There are many pieces of evidence that support the theory of evolution. Darwin relied on the similar anatomies of species to link them. He also had some fossil evidence that showed slight changes in the body structure of the species over time, often leading to vestigial structures. Of course, the fossil record is incomplete and has missing links. With todays technology, there are many other types of evidence for evolution. This includes similarities in the embryos of different species, the same DNA sequences found across all species, and an understanding of how DNA mutations  work in microevolution. More fossil evidence has also been found since Darwins time, although there are still many gaps in the fossil record. The Theory of Evolution Controversy Today, the theory of evolution is often portrayed in the media as a controversial subject. Primate evolution and the idea that humans evolved from monkeys has been a major point of friction between scientific and religious communities. Politicians and court decisions have debated whether or not schools should teach evolution or if they should also teach alternate points of view like intelligent design or creationism. The State of Tennessee v. Scopes, or the Scopes Monkey Trial, was a famous court battle over teaching evolution in the classroom. In 1925, a substitute teacher named John Scopes was arrested for illegally teaching evolution in a Tennessee science class. This was the first major court battle over evolution, and it brought attention to a formerly taboo subject. The Theory of Evolution in Biology The theory of evolution is often seen as the main overarching theme that ties all topics of biology together. It includes genetics, population biology, anatomy and physiology, and embryology, among others. While the theory has itself evolved and expanded over time, the principles laid out by Darwin in the 1800s still hold true today.

Mrs. Fields Write Up... ISMG 3000 Case Study Example | Topics and Well Written Essays - 1250 words

Mrs. Fields Write Up... ISMG 3000 - Case Study Example This was followed by the creation of Combination Stores that were not merely Cookie Selling Stores but also offered a wide range of other bakery products like Croissants, Bread, Hot Soups and sandwiches etc that were all being sold initially under the brand name of La Petite Boulangerie separately that had now been purchased by the Fields’. Moreover, these were not only store outlets but were sit-down cafes as well. The Field’s took these actions because they wanted to expand on their existing business. They were afraid that their name was well established in the present times but this may not be persistent and the monotony in their products and sales outlets may lead to the drifting away of their trusted customers as well. Since they were earning stable benefits and all their business processes were running smoothly Mr. Field thought that the merging of one or more companies into their existing setup would bring the well hailed boost to their product line. Mr. Field was primarily eyeing the revenue that he expected would be generated when the merger of the purchased companies would eventually be complete. Mr. Field was foreseeing the purchasing over even more new stores as a result of the revenue he expected to earn after this practical merger. His main motive was that he will have enough profits to make future payments by them. The demographical strength of the fields’ store, he thought would not effect any slight fluctuations in the economy that might take place during the transitional process of incorporating new companies and earning profits for the further new companies that were expected to be added to the combinational Stores’ Chain. Being an LPB store manager I wouldn’t be the happiest person on Earth. The company thatwas managed by me was being sold to another owner and rather than being downsized. Thus the

Security versus privacy Essay Example | Topics and Well Written Essays - 1500 words - 1

Security versus privacy - Essay Example High security standards mean detailed checkup of individuals and hence a privacy concern. We needed to change our policies to cater for the changing threat scenarios. These came with an unavoidable trade-offs to be made between security and privacy, therefore, leaving room for supporters of each value to debate policies and applications. Security, however, should be preferred over privacy, as it ensures smooth functioning of our national system and guards our economic investments. It ultimately provides us with a threat minimized environment to practice our civil rights. Being the major entry or exit points, airports need a filtration system to ensure our own protection. Security should, therefore, be preferred over privacy concerns while checking passengers. However, since the two values are interlinked, a balance must be made to address concerns of privacy while maintaining desired level of security. This balancing must not overrule security requirements, but find ways within proce dures to settle privacy concerns as much as possible. The paper will look into the issue by incorporating sources from the web, reports and personal experiences and takes into account, concerns by advocates of privacy. Security is considered as the most overpowering aspects to any value, such as privacy. Survival is our most quantified preference and we need survival to enjoy any other aspect of our lives. Security measures have far reaching physical and psychological aspects than visible to our naked eye. These measures reduce terror threats and provide us with psychological security to give us the freedom to enjoy our lives. It may be argued that this security comes at a cost of our privacy, but in fact it provides us with psychological freedom to practice our civil rights and freedom privately, at a fraction of inconvenience. Airport security systems are the best examples to evaluate the

Discuss what you believe to be the purpose(s) of education today Essay - 1

Discuss what you believe to be the purpose(s) of education today - Essay Example â€Å"From various parts† is depicted by the fact that there are students and professors for each and every department of knowledge. In its rudimental and simple form, it’s a school of knowledge of each kind, consisting of learners and teachers from every quarter. A university in its sense seems to be a place for the circulation and communication of thoughts, through means of personal intercourse, over a wide range of country. A university contemplates our nature’s necessity and is one specimen within a particular medium, from many which could have been adduced in others, with a provision for that necessity. In a broad sense of word, mutual education, is among the incessant and great occupations of human society, that is carried on partially with set purpose and partially not. One generation forms the other; the existing generation is acts and reacts upon itself within the people of the individual members. Books, in this process, are one special instrument. It’s emphatically so and true in this age. Putting into consideration the prodigious press powers, and the way they are developed during this time in the never intermitting issue of tracts, tracts, periodicals, works in series, light literature and pamphlets; we have to allow that there was never a time that fairer dispensing every means of instruction and information. Spayde Jon (2000), views street education and college education as the different aspects of education. The question however is that among the two educational aspects, which one is more necessary and relevant for survival in the world today. Maybe education cannot provide the necessary tools for survival in the real world. As much as we aren’t wasting time in institutions; the real world usually is a bigger school as compared to the other schools that we attend. The definition of school in the 21st century, unfortunately, is technology for instance. Spayde Jon (2000) argues that for our

Design of Wind Turbine Control

Design of Wind Turbine Control ABSTRACT The main objective of this report is the design and analysis of the control of the wind turbine. In order to ensure an efficient energy capture from the wind and at the same time the mitigation of loads at natural frequencies, it will be designed the operating strategy of the machine. Furthermore, the control of the wind turbine will be also designed in order to ensure a stable performance of the system given the stochastic nature of the wind. As a last task, it will be analysed the differences and importance of having a system with a good or reduced crossover frequency. Introduction The exploitation of wind energy is undoubtedly the most popular tool for the tackling of climate change all over the world. The development of wind turbines has led to a variable speed pitch regulated configuration that aims to extract energy from the wind as efficiently as possible. As the penetration of wind energy becomes more and more significant in modern power systems, there is a need to meet certain criteria and quality of generation in order to maintain the reliability and security of supply above certain levels. In order to achieve an optimize energy capture and prevent the machine from excessive loads, the design of both operating strategy and controller of the plant need to be carried out. The difficulty of the design relies on the stochastic nature of the wind, so a carefully and detailed approach is needed. Also, as the controller of the turbine is the heart of its operation, the design of this will become more and more difficult with the size of the turbine [1]. The larger the turbine, the more structurally flexible the mechanical parts will become and it is at this point where the fatigue loads become a major concern, as they are closely related to the operating life of the machine and also to the operational and maintenance costs. The purpose of this report is to highlight the importance of the controller and the contribution to the energy capture, as well as the design of a suitable operating strategy that maximized the reduction of loads while ensuring an efficient performance. 2.1 Baseline and procedure The main objective of the control design of any wind turbine is to obtain a good trade-off between energy and loads. In variable speed pitch regulated turbines it is controlled both pitch and torque. The former is controlled to limit the aerodynamic power in above-rated power (hence, the loads), while the latter is primarily used to control the transmission torque in above rated wind speeds and to maximize energy capture below the rated power region. The operating strategy must be carefully design in order to achieve maximum power capture while limiting the aerodynamic loads in the mechanical parts of the wind turbine, as they are critical aspects of the lifetime of the machine. Therefore, the design of the operating strategy must include load reduction as an explicit objective. In this report, the design of the operating strategy has been carried out with a special focus on the control of the tower and drive train resonances, as well as the mitigation of the blade loads. In order to design the operating strategy, it has been provided a model of a 1.5 MW variable speed, pitch regulated turbine. In the model, it was obtained the mechanical characteristics of the machine (Blade length, Gearbox ratio and so on), along with the power coefficient values for below rated operation, where the pitch of the blades was -2 degrees and is fixed for below rated operation. With the above data, it was possible to set the Cp-ÃŽÂ » curve of the machine. This type of curves are used in wind turbine design to obtain rotor power for any combination of rotor and wind speed. By building this curve it is possible to obtain the maximum power capture. This is given by the power coefficient Cp, that it is a relationship between the power in the wind stream and the power generated by the turbine [2]. The desired operating strategy must try to achieve the maximum power capture, and hence the maximum value of Cp, and such operating point determines the optimum tip speed ratio ( ÃŽÂ »), which is the ratio between the rotor speed and the wind speed. Once the optimum point of power extraction is set, it is possible to build the model of the machine. For this machine, the generator will operate in a range between 1 rad/s and 170 rad/s. Therefore, having the gearbox ratio, it is possible to obtain the rotor speed given the following equation: By obtaining the range of rotor speeds of the machine, it can now be calculated the necessary wind speed for each rotor speed with the following equation: Where ÃŽÂ » represents the optimum tip speed ratio of the machine, which corresponds to a value of 8.4 in this design (for a Cpmax of 0.47). This range of wind speeds is used to obtain the aerodynamic torque, which is a function of the rotor speed and wind speed (when the pitch angle is fixed). Therefore, it is possible to derive the aero torque by the following equation: Where the values of and correspond to the optimum operating point. That is, for a given wind speed and rotor speed, the objective is to produce a torque such that the power extraction from the wind is maximum. Thus, the above equation will provide the torque values for the maximum energy tracking region. On the other hand, it is necessary to obtain the generator torque, as this will be used in order to determine the end of the first and second constant speed (To and T1). As it can be seen in the equation below, the damping losses have been considered. For this design, a damping of 5 has been assumed. The generator toque can be obtained by the following equation. Now it is possible to obtain the power generated in the machine by having an efficiency of 95% in this machine: And the torque at rated power of the machine is given by: The point where the rated power curve crosses with the second constant speed line, will determine the torque which will be generating at above rated operation. Finally, it has been calculated the values for the constant speed curves of the operating strategy. It has been applied equation 2.3, setting the wind speed constant (from 4 m/s to 12m/s) and calculated the torque for the different values of Cp and ÃŽÂ ». The resulting operating strategy will be such that will cross every constant wind speed by the point at which is the optimum power extraction point (Cpmax). 2.2 Operating strategy process Several factors must be considered in an operating strategy design. Having obtained the values in the previous section, it is possible to plot the maximum power extraction curve. The design must have special focus on the natural frequencies of the tower and blades. For this design, it has been provided the natural frequencies of both components. For the tower, the side-side and fore-aft frequencies. For the blades, the edge and flap frequencies were provided. Based on this, it must be analysed and compare those frequencies with the rotor speed (P), the 3P and the 6P component. It is desirable to design an operating strategy that avoids operating at multiples of the structural frequencies, as they are critical points of operation where the mechanical loads increase and the lifetime of the turbine can be reduced due to fatigue loads. Besides, the strategy must ensure a smooth switching at the first and second constant speeds with the operating curve. This has been achieved by setting both constant speed lines with a minimum length, in such way that the controller of the turbine is switching the to different operation modes excessively, as this could reduce the efficiency of the machine. Another important aspect to look at when designing the operating strategy, is to ensure that the wind turbine operation is not close to the stall front. The stall front curve is the curve that connects the maximum point of the constant wind speed curves. It determines the beginning of the stall region where the blades will be exposed to high loads and the power extraction will not operate efficiently. Based on the above, the design of the operating strategy was carried out. The first constant wind speed was set at 1.2 rad/s, avoiding a 6P frequency in the blades (flap natural frequency) that would appear at approximately 1 rad/s. As the design of the operating strategy must be a trade-off between energy capture and reduction of loads, it was decided the above as the best option for this machine. Rotor speed (rad/s) Generator torque (Nm) Aerodynamic Torque (Nm) Fist constant speed region (end) T0 1.2 1432.923 163076 Second constant speed region (beginning) T1 2.02 4640.24 462004 Rated torque 2.02 10137 853106 Table 2.0 generator torque at constant speed switching point The beginning of the second constant speed region is determined by the maximum generator speed which has been set at 170 rad/s (2.02 rad/s at the rotor side). It can be seen in Figure 2.0 the operating strategy curve of the machine, where it can be appraised that the operating strategy has avoided the 6P natural frequency stated above. The stall region is far enough from the operating region of the machine, ensuring a good performance and better efficiency. Figure 2.0 Aerodynamic torque-rotor speed diagram. Operating strategy curve of the wind turbine 2.3 Discussion of results In general terms, the design of the machine has been successfully carried out, as it can be seen in Figure 2.0, covering the following critical aspects of any operating strategy of a wind turbine: After carefully analysed the natural frequencies and compared with the 3P and 6P resonance frequencies, it has been set the cut-in speed of the machine at 1.2 rad/s. Also, this strategy will ensure that the damping losses in the machine do not have excessive effect on the power generated, as at very low rotor speeds the losses can overcome the power generated. The operating strategy ensures that the turbine will operate between the desired wind speed range. In this report, it has been set the wind speed range between 4m/s and 25m/s. It has been secured a smooth switching transient between the two constant speed regions and the maximum power tracking curve by establishing a reasonable size of the constant speed regions. It could be arguable whether this operating strategy is the most efficient or there are better options that would adapt to this wind turbine. The truth is that there are multiple options and different strategy plans depending on the preferences of the design. In this report, the aim has been to find a trade-off between load reduction and efficient power capture. 3.1 Baseline and procedure In order to achieve an efficient operation of the wind turbine, the control must play an important role in the operating strategy. An appropriate wind controller design will allow for a better wind energy capture as well as the mitigation of fatigue loads, as they considerably reduce the lifetime of the machine. Hence, the control task of a wind turbine is to maintain the appropriate operational state as the wind speed condition change, as well as enhancing its dynamic properties. In this report, the main goal is to design the operational controller, which is divided in two different regions, below rated and above rated power. At below rate conditions, the aim is to extract as much power from the wind as possible. This will be achieved by varying the reaction torque by measure the rotor speed or the output power. The second task of the controller is to ensure a smooth transition between the 1st constant speed region and the maximum power tracking curve. At above rated operation, the performance of the turbine will be carried out by pitching the blades. By doing so, it will allow the turbine to maintain the generation at the rated power value, take action to alleviate the increased loads at different parts of the wind turbine and to keep the desired stability margins of operation. For the above rated controller, it will be used a PI pitch controller along with an extra pole and zero and the set gain of the transfer function, resulting the transfer function as following: The nonlinearity nature of the wind turbine operation leads to a nonlinear control design. The gain scheduling is the most used control technique to accommodate the nonlinearities [3]. The performance of this technique is to continuously change the structure of the controller according to the local set points, such as aerodynamic torque, rotor speed and pitch angle. For instance, as the torque sensitivity varies nearly linear with pitch angle, it can be compensated by varying the overall gain of the controller linearly with pitch angle. As the design of the above rated controller is normally more tedious, it will be first designed the above rated controller and then, by varying the gain, redesign the below rated controller. Besides, when designing the controller of variable speed pitch regulated wind turbine, it must be paid special attention to the damage caused by the vibrations on the drive train, as it produces serious risks of failure. It has been noted that for the case of the wind turbine in this that the first drive train mode need to be actively damped, in order to alleviate the large torque transients at 13 rad/s. To obtain the transfer function of the drive train filter, it will be the general form of a band pass filter: The block diagram with the filter integrated can be seen in Figure 3.0. The design of the filter will be designed such that the filter feeds back only the oscillations at the resonant frequency. Figure 3.0 Plant with the drive train filter implemented As the drive train filter is located at the feedback loop, the equivalent transfer function of the plant and the filter will be given by the following equation: 3.2 Drive-Train Filter and Controller Design Drive Train Filter Design In order to damp to suppress the peak at the first drive train mode, it has been designed the transfer function of the filter. To do so, three parameters have been set in the transfer function. The gain (k), the frequency at which it is aimed to amplify in the feedback loop () and a scaling factor (n), which is used to set the frequency of the poles in the transfer function. After a trial and error procedure in MATLAB, the transfer function designed is the following: In Figure 3.1 is shown the Bode diagram of the system with and without drive train filter. It can be appraised that the peak in the drive train mode has been successfully damped, reducing the mechanical loads in the machine and hence, improving the lifetime of the turbine. Figure 3.1 Bode plot with the effect of the drive train filter in the system Controller Design for Above and Below Rated operation To control rotor speed and torque it is necessary to use pitch of the blades at above rated wind speeds. It has been designed a complete controller for the turbine for smooth switching between different operating modes. Apart from the pitch-PI controller, the gain scheduling technique has been applied to the design for the non-linear design section. The controller must assure a gain and phase margins above certain levels (4 dB and 30 degrees respectively) when checking the stability using the open loop functions, providing stability for the closed loop system. The aim is to provide good disturbance rejection at low frequencies, the required bandwidth at 1 rad/s, and good high frequency roll-off. With these main objectives, the transfer function designed for the given wind turbine is the following: It is shown in Figure 3.2 the Bode diagram of the controller, where it can be appraised the effects that the poles, zero and gain have on the systems. The proportional gain of the transfer function sets the initial gain value (20 log10 (|k|) and remains constant with the frequency. The proportional gain does not contribute to the phase of the transfer function.   Ãƒâ€šÃ‚   Figure 3.2 Bode diagram Above Rated Controller The pure integrator , produces constant gain contribution of -20 dB/dec from an infinite frequency. It also produces a constant phase of -90 degrees. The pole in the transfer function contributes to the gain with a negative 20dB/dec slope at its frequency of operation (1.95 rad/s). With respect to the phase, it contributes with a -45 deg/dec between a decade after and a decade before its frequency. That is, for a frequency of 1.95 rad/s, it starts to contribute at 0.195 rad/s and will end at 19.5 rad/s. The zero in the transfer function contributes to the gain with a positive 20 dB/dec slope and with a positive 45 deg/dec slope for the phase. Analogous to the pole, the phase contribution starts and ends one decade before and after the frequency of the zero. Knowing the above concepts and after a trial and error procedure, the gain scheduling technique was implemented and the design of the controller has been successfully completed. It can be seen in Figure 3.3 and 3.4 the differences between the effect of gain scheduling. It has been designed the controller for the plant dynamics at speeds of 12m/s,15m/s and 25m/s and applies for the same system with and without gain scheduling. Figure 3.3 Bode diagram of the plant without gain scheduling Figure 3.4 Bode diagram of the plant with gain scheduling It can be appraised that the system with the effect of the gain scheduling becomes stable, while without the gain scheduling system the gain and phase margins do not meet the requirements stated above for a feasible strategy. The design of the controller gives a positive gain and phase margin to the system at 1rad/s, ensuring the rejection of disturbances above these frequencies [4]. Once the above rated controller is designed, it has been carried out the design for the above rated operation. It has been tested for below rated wind speeds of 4m/s and 10m/s (resulting roughly the same response) and as it can be seen in Figure 3.5, the system has been successfully integrated as the phase and gain margin meet the specified requirements. As part of the gain scheduling implementation, the transfer function of the controller for below rated condition will just adjust the gain of the transfer function. After a trial and error procedure the transfer function obtained is given by the following equation. Figure 3.5 Bode diagram of below rated operation (with drive train filter) Note that for the below rated system analysis, there must be included the drive train filter at the feedback loop. 3.3 Discussion of results Based on the results, the design of the controller by applying gain scheduling technique has been successfully completed. As in any controller design, it must be aimed for good stability margin, both phase and margin, otherwise the system could destabilize and therefore cause high load fluctuations. Both below and above rated controller have been designed accordingly to these requirements and the phase and gain margin meet the minimum stablished (4dB for gain margin and 30 degrees for phase margin). 3.4 Effect of wind turbine size in the controller design. An important aspect of the controller design of a wind turbine is the size of the aforementioned. The wind turbine industry is going towards an increasingly bigger size of the turbines, which brings out new challenges when it comes to the design of the controller of the machine. As the rotor is continuously interacting with a very complex wind field, the prediction of the behaviour of the machine will become more difficult with an increase in size. In other words, as the size of the machine increases, it might be extremely difficult (when not impossible) to achieve the desired margins of stability, as the structural elements will become more flexible and dynamically more active. This does not necessarily mean that the system will become unstable with a bigger turbine, but proposes that controller need to be designed and tuned more carefully as the gain and phase margins will reduce. 4.1 Baseline and procedure As stated in section 3, the importance of the controller remains at the stability of the system. A system with low crossover frequency will present more fluctuations and a poor stability in terms of power generation, rotational speed or generator torque. The aim of this section is to give a better understanding of the design of a system with acceptable crossover frequency and also the importance of the drive train filter design, which as it was shown in the previous section, will help to damp the first drive train mode and therefore considerably reduce the mechanical loads. The will be compared for variables of the wind turbine for both above and below rated operation. The first tasks have been the comparison between the system with good crossover frequency and the system with no drive train filter. In order to do so, it has been compared the power output of the machine, the generator speed, generator torque and the pitch angle. For simplicity on the interpretation of the results, it will be compared the simulations at 15m/s of wind speed (above rated operation), and 9m/s of wind speed (below rated operation). For each wind speed, different turbulence of the wind field has been analysed. The second tasks have consisted on the comparison between a system with a good cross over frequency and a reduced cross over frequency. Again, to give the reader an easier understanding of the simulations, it will be compared the different systems at a wind speed of 15m/s. 4.2 Investigation of the controller performance Comparison between the good cross over frequency and no drive train filter systems It can be appraised in Figure 4.0, the power output of the turbine for wind speeds of 15 m/s and 9m/s. It is immediately apparent that for each speed, the higher the fluctuation, the higher the disturbance and therefore the less efficient energy production of the turbine. The mean production for 15m/s and higher disturbance accounts for 4.83MW and for 9 m/s is 2.8 MW. Compared with the wind field with small disturbance, the differences are not very noticeable, as the production accounts for approximately 4.7MW and 2.4 MW respectively. With respect to the comparison between the different systems, the figures show negligible differences between the system response at different disturbances. This is because both systems have a crossover frequency of 1 rad/s. Besides the reason why the system with no drive train filter seems to have no effect on the system is because as stated in section 3, the aim of the filter is to damp the drive train mode at a certain frequency. As it is being plotted the response over time, the slightly differences at the frequency of damping cannot be appraised in these figures. Figure 4.0 Power output of the turbine for 15m/s and 9m/s In terms of the generator speed (Figure 4.1), the same pattern than in the power output has been acknowledge. The higher the turbulence intensity in the wind, the more difficult the control of the generator speed, and therefore the higher the fluctuations. In terms of mean values, the 15 m/s wind speed produces a mean generator speed of approximately 120 rad/s for a high turbulence intensity, and 111 rad/s at 9m/s of wind speed. Figure 4.1 Generator speed of the turbine for 15m/s and 9m/s Talking about the generator torque, it presents the same patterns than the previous simulation, as it can be seen in Figure 4.2, where there are no apparent differences between the two systems, and the turbulence intensity influence the variation of generator torque. The mean values for the higher turbulence intensity are 26.2KNm and 42.4KNm for 9m/s and 15m/s respectively. For the lower fluctuation of wind, the mean values of torque account for 22.7KNm and 42.7KNm. Figure 4.2 Generator torque of the turbine for 15m/s and 9m/s As a final analysis, it has been plotted the pitch angle for the different system at different speeds. It can be appraised in Figure 4.3 that the pitching of the blades does not perform at 9m/s, except when the turbulence intensity is significantly high, in which case it might overpass the above rated wind speed and therefore the pitching start to act. By contrast, for the 15m/s simulation speed, the pitching angle varies constantly trying to absorb energy from the wind more efficiently. Figure 4.3 Pitch angle of the turbine for 15m/s and 9m/s Comparison between reduced and good crossover frequency It has been simulated the response of the two system with good and reduced crossover frequency. The good crossover system has a crossover frequency of 1 rad/s while the reduced crossover system is 0.5 rad/s. The results are shown in Figure 4.4 and 4.5, where some differences can be noticed. The reduced crossover frequency system has a more unstable generation of power for both turbulence intensity scenarios. As stated in Section 3, the system with a reduced crossover frequency will have a poorer performance under disturbances and will reject those more inefficiently than the one with a good cross over frequency. Figure 4.4 Power output and generator speed of the turbine for 15m/s and 9m/s Figure 4.5 Generator torque and pitch angle of the turbine for 15m/s and 9m/s Having designed and analysed the different aspect of a wind turbine controller, it can be concluded that the design has been carried out successfully, ensuring a stable performance of the system with an efficient mitigation of loads. It can be argued whether the design of both operating strategy and controller are the best option in terms of performance, but the main objective of this report is to give an understanding of the performance of the machine and the control system operation, as well as to understand the new challenges that the increasingly size of the wind turbines might bring to the design of the control strategy. [1] E. A. Bossanyi, The Design of Closed Loop Controllers for Wind Turbines, Wind Energy, vol. 3, pp. 149-163, 2000. [2] T. Burton, Cp-lamda performance, Chichester, Willey, 2011, pp. 173-174. [3] A. P. Chatzopoulos, Full Envelope Wind Turbine Controller Design for Power Regulation and Tower Load Reduction, University of Strathclyde, Glasgow, 2014. [4] H. D. B. A. R. J. M. Fernando D. Bianchi, Control of Variable-Speed Variable-pitch Wind turbines Using Gain Scheduling Techniques, in Wind turbine control systems, London, Springer, 2007.

“Cyberschool” by Clifford Stoll Essay

Cyberschool is a story well written by Clifford Stoll, who shows us what Cberschool is. Cyberschool is an idea, a reform, and a solution that has been explained in the story. The idea of Cyberchool is ironic and unceremonious, or at least explained that way. The use of technology is in play, trying to expand education by using technology. As a reform, they discussed getting rid of teachers, and that would cut back lot of other opportunities. Seeing a teacher is one thing that your not able to do, and sometimes is very important to get a face to face experience. It also eliminates luxuries such as, art lessons, and field trips. All these things that are being eliminated recoup the price of what’s spent on the computers. Money as well would have to be spent on CD-ROMs for educational games. Cyberschool is said to showcase technology and train students for the upcoming electronic workplace. Author Clifford Stoll expresses Cyberschool theme to us as tremendously satirical and informal. Bringing back reform, the paper is shown that it’s supposed to help, but rather far from that. Clifford Stoll has well expressed his thoughts, and theme with a clear understanding, but still slacked on some certain occasions. The idea is just crazy, but some may find it genius. After reading Cyberschool, it kept reminding me of online classes. I have personally taken them, and find them not as bad as some may think. It is an advantage to have a face-to-face discussion with a teacher though. If at anytime have questions, they wouldn’t be able to get the same answer as a teacher would give. Cyberschool to me was a well-written plan, and had ups and downs. It could save money and cost money, for example, getting rid of teachers, and buying computers and CD-ROMs.

Family Means

When asked â€Å"what does family mean? † I automatically think of the legal definition. The legal definition of family is a group of individuals consisting of parents, siblings, children, and other relatives, who have ties of blood, marriage, or adoption. Now that the legal definition is out of the way, we can get to my definition. Family also known as kin, folk, clan, relatives, or dynasty, to me is a little bit different from the legal definition. Family to me is a group of people who love you unknowingly but still unconditionally.Family is where you can be yourself and for me that is probably one of the turning points between family and close friendship. To others family might be the group of people that you tell boring stories to just because you know that regardless of anything they are still your family. There are times I find it hard to sleep at night and I text my cousin Lindsey and no matter what happens, I can tell her about it and she doesn't say anything to anybod y. There was one time when I thought I was failing a class because, this year especially, I feel like i'm slacking a little bit.So I told Lindsey about it and she said â€Å"stop playing games and study because I know your grandma does not play. † Just that one line kind of put everything in perspective because my grandma, no matter how nice she may seem, she really doesn't play when it comes to grades and her family. Family in short can make someone a part of something bigger than themselves. Family is the one word that can make someone go back somewhere they really didn't want to ever go back to. Some family members make you mad, angry, upset, frustrated.Some make you want to call them every name in the book, and by book I don't mean the Bible. But, at the same time your  family is the only thing you can find yourself confiding in, and crying to, and loving more than ever. So when it comes to family no one should feel like they have to have some type of guard up because t hese are the people that are supposed to care the most. Everyone's definition of family or kin is different but, to me that is what it should be. What's your definition?

Ladybugs, Family Coccinellidae

Ladybugs, Family Coccinellidae Ladybugs, or ladybirds as they are also called, are neither bugs nor birds. Entomologists prefer the name lady beetle, which accurately places these lovable insects in the order Coleoptera. Whatever you call them, these well-known insects belong to the family Coccinellidae. All About Ladybugs Ladybugs share a characteristic shape- a dome-shaped back and a flat underside. Ladybug elytra display bold colors and markings, usually red, orange, or yellow with black spots. People often believe the number of spots on a ladybug tells its age, but this is not true. The markings may indicate a species of Coccinellid, although even individuals within a species can vary greatly. Ladybugs walk on short legs, which tuck away under the body. Their short antennae form a slight club at the end. The ladybugs head is almost hidden beneath a large pronotum. Ladybug mouthparts are modified for chewing. Coccinellids became known as ladybirds during the Middle Ages. The term lady references the Virgin Mary, who was often depicted in a red cloak. The 7-spot ladybird (Coccinella 7-punctata) is said to represent the Virgins seven joys and seven sorrows. Classification of Lady Beetles Kingdom - AnimaliaPhylum - ArthropodaClass – InsectaOrder – ColeopteraFamily - Coccinellidae The Ladybug Diet Most ladybugs are predators with ravenous appetites for aphids and other soft-bodied insects. Adult ladybugs will eat several hundred aphids before mating and laying eggs on the infested plants. Ladybug larvae feed on aphids as well. Some ladybug species prefer other pests, like mites, white flies, or scale insects. A few even feed on fungus or mildew. One small subfamily of ladybugs (Epilachninae) includes leaf-eating beetles like the Mexican bean beetle. A small number of beetles in this group are pests, but by far the majority of ladybugs are beneficial predators of pest insects. The Ladybug Life Cycle Ladybugs undergo complete metamorphosis in four stages: egg, larva, pupa, and adult. Depending on the species, female ladybugs may lay up to 1,000 eggs within a few months from spring to early summer. Eggs hatch within four days. Ladybug larvae resemble tiny alligators, with elongated bodies and bumpy skin. Most species go through four larval instars. The larva attaches itself to a leaf, and pupates. Ladybug pupae are usually orange. Within 3 to 12 days, the adult emerges, ready to mate and feed. Most ladybugs overwinter as adults. They form aggregates, or clusters, and take shelter in leaf litter, under bark, or other protected places. Some species, like the Asian multicolored lady beetle, prefer to spend the winter hidden in the walls of buildings. Special Adaptations and Defenses of Ladybugs When threatened, ladybugs reflex bleed, releasing hemolymph form their leg joints. The yellow hemolymph is both toxic and foul-smelling, and effectively deters predators. The ladybugs bright colors, red and black in particular, may signal its toxicity to predators as well. Some evidence suggests that ladybugs lay infertile eggs along with fertile ones, in order to provide a food source for hatching larvae. When the natural food supply is limited, the ladybug lays a higher percentage of infertile eggs. Range and Distribution of Ladybugs The cosmopolitan ladybug can be found throughout the world. Over 450 species of ladybugs live in North America, though not all are native to the continent. Worldwide, scientists have described over 5,000 Coccinellid species.

American Developments 1860-77 essays

American Developments 1860-77 essays During the time period of 1860 1877, we fought to determine what position we would assume on many controversial issues. Black suffrage and the power of the national government against the power of the states were the two most prominent topics. The Constitution underwent crucial changes, reforms, and developments, yet Americas society, though affected by the Constitution, changed very little. God forbid these changes be called developments. South Carolina threatened secession because they were being denied many rights that were delegated to them by the Constitution. South Carolina and a better portion of the South felt that they had been denied their right to own slaves, because the federal government had left it up to the states to decide their position on slavery through popular sovereignty. Later, after the republicans had full control of Congress, they passed numerous bills freeing and benefiting the African-Americans. (Document A, American Pageant, Document D) With what seemed to be a follow up on former President Lincolns Emancipation Proclamation, Congress passed the 13th amendment accomplishing what Lincoln could not, freeing all the slaves. Still not satisfied, and yearning for equality the blacks called out for fair treatment and the 14th and 15th amendments were passed making African-Americans made primary citizens and granting them the right to vote. All the while encouraging the states to allow freedmen to vote. For a short time period Congress seemed like it was trying all that it could to promote black equality. (American Pageant, Document H) The Freedmens Bureau was formed to help the freedmen of the South find jobs and/or land to homestead. There were also many sympathizers that tried to help blacks utilize their newfound rights guiding them in gain offices, negotiating contracts, and voting. The scallywags and carpetbaggers within these groups promised to every freed sl...

The Phenomenon of Georgia OKeeffe Research Paper

The Phenomenon of Georgia OKeeffe - Research Paper Example With the combination of thin paint and her natural ideas put O'Keeffe years ahead of her time. O'Keeffe ancestors were of Irish and Hungarian origin. She grew as a thoughtful child who did things in a manner that was her own way. She decided to become a painter at a very early age and she said "That was the thing I can do the best because that was nobody else's business." Georgia O'Keeffe was a teenager when she moved to Williamsburg with her parents. At Williamsburg she attended the CPEI "Chatham Protestant Episcopal Institute" from where she graduated in the year 1905. In 1907 she joined Art Institute at Chicago and in the same year she also joined the Art Students League at New York. Her artistic ability developed when she started to draw the paintings using oil paint on the piece of canvas. She made a famous oil painting of "Dead Rabbit with Copper Pot." As a result scholarship was awarded to her and it was an early indication of O'Keeffe being a genius. (Weingarten, & Higgerson, 2001) This gave Georgia a sense of achievement as she felt her work very different from the other still painters of her time and the ones before her. For a very brief period she worked as a freelance commercial artist in the city of Chicago. Later she became an arts teacher at Chicago and considered this work to be more pliable. In the year 1914, she became supervisor of art for all the public schools in the city of Amarillo, Texas. In 1920 she became head of the department of art at the College of Normal in Canyon, Texas. (Weingarten, & Higgerson, 2001) In this period O'Keeffe stop painting for a while and studied the art theories of "Arthur Wesley Dow" who was a famous lecturer of art at the University of Columbia. Georgia learned to find and create two dimensional reality in pictorial art. Dow also taught her that these realities must be based on pure aesthetic principles and taught her that composition of pictorial art should be abstract and it must be based on color, line, dark masses and light, symmetry and repetition. O'Keeffe also learned that all these things are important along with solitude, state of isolation and emotional ferment. Georgia O'Keeffe Life in New York Georgia O'Keeffe had a boyfriend with whom she had a conflict over something and that gave her some personal touch in the field of art. All these factors contributed in starting full time painting once again. She experimented with watercolors, oil paints and also the drawing using charcoal. In 1915 Georgia mailed few of her charcoal drawings to her friend who lived in New York. These charcoal drawings brought her artistic immortality. The reason for this was that her friend showed these drawing to Alfred Stieglitz, who was a renowned photographer. Alfred Stieglitz exhibited all these drawing at "Art Gallery 291" on 5th Avenue in New York. These drawing drew the attention of general public. As a reticent person O'Keeffe went to New York to oppose the display of her drawings and demanded an immediate removal. However Stieglitz persuaded her and he wanted these paintings to remain and also wanted her to continue her carrier for her own interest in abstract designs. (Reily, 2007) The d esigns used by Georgia were bud-like forms which where rounded and jagged between undulating

Hispanic Diversity Essay Example | Topics and Well Written Essays - 750 words

Hispanic Diversity - Essay Example Diverse workforce acts as a competitive advantage to the companies. To a large extent organizational performance depends on handling its diversity issues. For selling products and services companies needs to handle many diversity issues because of their wide range of diverse customers. Organizations need to know diverse language, cultures, customers etc for fulfilling the needs and requirements of their customers and employees. This facilitates the company in achieving their goals and objectives (Jose 141). When a company understands the diverse needs, expectations and requirements of its organizational members and customer then it can enhance its business process and services which facilitates the firm in improving its performance and holding its place in the competitive global market. People of different cultures and countries are presently residing in U.S. Spanish people are presently dominating the U.S market. Business people, students, serviceman etc reside in U.S. Other than Spanish, people from another country like China, Latin America etc reside in the U.S. the basic differences among these people are in their culture, customs, habits etc. Hispanic people have covered the maximum part of U.S market. Hispanic people are very much associated with their family, unlike the present American people. The Spanish and Latinos people take care of their parents when they grow old. But the people of other cultures residing in America are very much concerned about themselves. American society believes in individualism but Hispanic people believe in collectivism. People of different income level stay in the U.S which enhances the socioeconomic differences in this state (Maffi 140). The market and workplaces of U.S are characterized with all of these differences for which companies operating in U.S market are trying to manage diversity issues.