Comparison of HVDC and HVAC transmission systems

Comparison of HVDC and HVAC transmission systems A substantial development of offshore wind farms is taking place in different parts of the world, yet the major issue is the technique used to transfer the energy from the wind farms to the grid. Two of the major technologies used are: High-Voltage DC known as HVDC and High-Voltage AC known as HVAC. The main concern of electrical power engineers is that the transferring of energy occurs with low losses. Taking that into consideration, the advantages and disadvantages of both technologies have been studied and compared in order to choose the most efficient scheme. The HVDC system has been put in many power transmission projects, even though some disadvantages have been spotted. The components used in this system are as follows [1]: * AC and DC filters * Converter Stations * Smoothing reactor * DC cable and return path * Cooling devices Converters in this system have been the element of inconvenience for several reasons. Some of these reasons is that converters are relatively high in price; moreover they need reactive power and have the potential to produce lots of harmonics. In addition, the HVDC system has a restricted ability when it comes to the handling of overloads. Furthermore, the most important negative aspect in HVDCs is the treatment of faults. Noting that the rated power of the recent circuit breakers tend not to be so high which in return introduces us to another problem, and this is that the current and voltage in a DC line can never traverse 0. This however makes it tough to solve the fault, but a solution has been found and it is done by the help of the AC lines circuit breakers [2]. On the other hand, HVDC systems are characterized by its admirable advantages. The latter, is considered to be uncomplicated when it comes to construction. This had a positive effect on the system since it allows it to b e interconnected at different frequencies and causes the short circuits in the DC lines to become minimized. Moreover, there is no significant environmental effect since there will be no interference with the radio electromagnetic waves and the corona effect is supposed to be even less. Finally the DC system supplies an adaptable and a relatively fast power flow [2]. The following figure shows the interconnection of offshore wind turbines with HVDC technology [2]: On the other hand, the HVAC system has almost the same advantages as the HVDC but its disadvantages are distinct. For instance, the underground HVAC cables have very low characteristic impedance and yet it needs a very high charging current. Moreover these cables are not able to pass on any load. This makes the DC cables more popular since the mentioned drawbacks are not part of their characteristics. On the other hand, the earth-return ability is available with HVDC transmission and not with the HVAC system. Major analysis has been made on both HVDC and HVAC and it was realized that distance plays a major role in the amplitude of losses. According to Brakelmanns theory, the allocation of current along the cable and the temperature it possesses play a major role in the calculation of losses. The formulae used during calculation of power losses in the submarine cables are as follows [1]: However the formula used to calculate the losses in the HVDC cables is as follows [1]: It was realized that the power produced by both technologies is almost the same, yet the HVDC could achieve marginally higher voltages per conductor. Moreover, the distance over which the cables are stretched has an influence on the losses. HVAC system have minimum losses along short distances ranged between 50 to 70 km, while as the distance increases above 70 km it is preferred to use HVDC. The following graph shows the technology to be used as the distance gets longer [3]: More factors are taken into consideration, such as the cost, consistency, quality and technical capability. Quality wise, HVDC Light technology has been introduced to the market and its advantages for connecting offshore wind farms to the grid have been remarkable. One of the main features that make the latter more suitable than HVAC is the minimized area and mass of the cables. This however permits the HVDC cables to function under maximum electric field stress. Moreover, HVDC cables are preferred to HVAC cables when it comes to installation at a very deep range, since the mass of HVAC cables are double that of the HVDC cables [4]. Finally HVDC cables have been tested in systems of 150 KV and 400 MW were the result was positive [3]. The following figure shows a pair of submarine and land Light cables used for offshore wind farm connections [3]: Offshore HVDC Grid Building an offshore HVDC grid has been an idea that most of the European countries have been discussing. Not long ago these administrations and organisations have accepted it, yet taking into consideration the technical challenges within it. As mentioned above, the HVDC system is composed of two converter stations. The converters first used are the LCC (Line Commutated Converters), but a modern system has been introduced to the HVDC system and is called the VSC (Voltage Source Converters). The latter is considered better and more efficient than the LCC since its made up of a smaller amount of components, the circuit is easier to analyze when faults occur, and the has lower losses. The following figure shows the difference in both circuits [5]: The challenge concerning these converters is that when an offshore grid has to be built both converters need to be used, since most of the submarine cables constructed are for LCC yet can function with VSC. The solution is to build a system composed of both converters and this is considered hard because of two major drawbacks: The extremely high cost of the converters and the losses. Moreover one of the tough challenges is the consistency of the system, and this leads us to the issue of the circuit breakers that have to be more efficient in order to ensure that the system is protected. Finally, the problem seems to be the funding because the technology is available [5, 6].

Ethics in Project Management

ETHICS IN PROJECT MANAGEMENT 1ABSTRACT This essay will describe about ethics in project management which will provide us an overview of the aspects how the organizations develop the ethics in an organization and about the differences in the ethical decision making among various professionals in their given field. In order to understand various aspects of the chosen topic various literature have been examined including peer reviewed articles which have been carefully chosen. In today’s world all the professional fields have adopted the ethical code of conduct in one way or another but there are differences in the decision making because of variation in company culture and the ethical values of a project manager and the employees. 2INTRODUCTION Ethics basically define the values and the standards or customs of a particular person or a group of people. There are two things that provide the specification for the ethics. First, ethics refers to well based standards of right and wrong that set what humans ought to do, usually in terms of rights, obligations, benefits to society, fairness, or specific virtues. Secondly, ethics refers to the study and development of one's ethical standards. As mentioned above, feelings can deviate from what is ethical. So it is necessary to constantly examine one's standards to ensure that they are reasonable and well-founded. Ethics also means, then, the continuous effort of studying our own moral beliefs and our moral conduct, and striving to ensure that we, and the institutions we help to shape, live up to standards that are reasonable and solidly-based. To make good ethical decisions it is essential that the professionals must have trained sensitivity to the ethical issues and a methodology that will help in exploring the ethical aspects of a decision making. In the business world, ethics scandals have caused the downfall of global corporations and non-profits, causing public outrage and sparking increased government regulations. Globalization has brought economies closer together but has caused a realization that our practice of ethics may differ from culture to culture. The rapid, continuing pace of technological change has provided new opportunities, but has also introduced new challenges, including new ethical dilemmas. The Code of Ethics and Professional Development was approved by the PMI Board of Directors in October 2006. Breach of Code of Ethics: Should, in the opinion of the National Council, a breach or a series of breaches of the Code of Ethics indicate that the member concerned has conducted himself/herself in a manner seriously prejudicial to the profession, then the Council shall advise the member that his/her name shall be removed from the Register of Members and in the case of Registered Project Managers, from the Register of Project Managers. The other important issue is importance of monitoring to control unethical problems. There is no doubt, control is necessary to prevent unethical problems, especially illegal ones, like frauds, and it helps organisations to ensure the accepted policies perform properly. However, there are some possible conflicts here, especially about considering people’s privacy and answer to this question that how far should this control go? People do not like their personal actions to be watched by others and they expect their privacy to be respected, also in some situations, applying very strictly suspect view to control causes people feel to have to try to prove their innocence because someone thinks they are guilty. In my opinion, definitely people‘s right to have their privacy respected could not be ignored, but there are other rights for people too, they want to feel secure when they trust to an organisation and give their information to the organisation and it’s responsible to protect them against someone that tries to access the information and use it to abuse them, or they also want the information related to their banking transactions to be secure. In all of these cases, it is not a acceptable excuse to these organisations not to check their staffs’ or customers’ suspect actions just because of being care about respecting to people privacy rights. As we see, beside to privacy right, there are other rights that should be considered as well. So the someone privacy right should be respected as far as it does not provide possibility of break other people‘s right. Ethics in IT: Mentioned by Strassmann, there is an issue for which, about our personal responsibility to other’s unethical behaviour and deciding whether or not play the role of the ethics police for people including our colleagues, partners, customers or even our boss. Bill Nance, a professor of management information systems at San Jose State University, disagree with such a way of thinking, he believes this â€Å"don't ask, don't tell† policy might end up costing a lot more than the money saved by the illegal money-saving strategies. He gave reason that â€Å"If a client or co-worker is doing something that is beyond unethical –something that is illegal — and others involved know or `could have reasonably known,' as lawyers say in court, they could be considered an accomplice†. I personally think in this sort of situation expectation of always acting as a moral cop is to some extent idealist and not realistic; sometimes because of the side effects of playing such a role, it could cost too much, such as losing job or popularity, so it would not worth to do so. Following are the main objectives that are meant to be achieved with the implementation of ethics in the organization:- Inspiration: To inspire members of the profession to act more ethically in the work environment. Sensitivity: To give encouragement to the members to remain sensitive towards the moral aspects of their jobs Discipline: To enforce certain rules of the profession on its members to achieve integrity Advice: To provide advice in cases of moral complexity and ethical dilemma Awareness: To alert employers and clients as to what they can expect of the member when performing his or her job. Ethics in Construction: The American Society of Civil Engineers claims that corruption accounts for an estimated $340 billion of worldwide construction costs each year. Corruption (including bribery, embezzlement, kickbacks, and fraud) in construction projects undermines the delivery of infrastructure services. Further, corruption poses significant risks to construction and engineering companies themselves. Owners, while trying to minimize their costs for construction projects, are also required to address the ethical and social responsibilities to their shareholders. Terms such as â€Å"socially responsible investments,† â€Å"integrity,† â€Å"honesty,† and â€Å"ethical business conduct† can be found in the operation statements or codes of ethics of almost all public companies. Whistleblowing: In the past thirty years numerous pieces of legislation have been passed to offer protection to whistleblowers from retaliation for disclosing organisational wrongdoing. An area that remains uncertain in relation to whistleblowing and its related policies in organisations is whether these policies actually increase the individualisation of work, allowing employees to behave in accordance with their conscience and in line with societal expectations or whether they are another management tool to control employees and protect organisations from them. In the professional environment, defining what is ethical could be too subjective. So providing enough information about accepted ethical values is very helpful to make ethical decisions. In other words, it is organisations’ responsibility to have related ethical policies and inform people, who need to know about that, properly. Another point is that some people usually take lightly of what is considered unethical behaviour in the industry while they may think that this behaviour is highly unethical or even illegal in real life. This situation emphasizes necessity to pay more attention to cultural infrastructure to promote ethical issues e. g. in construction, medical or IT area. Finally, considering that The Project Management Institute does have a Code of Ethics and Professional Conduct, every professional should accustom to commit to the code seriously and adhere to it in all circumstances. Also enforcement of the ethical standards should be a must for the organization to maintain a reputation and also to protect the interest of the public. REFERENCES 1) Reedy, Patrick. 2008. ‘Mirror, Mirror, on the Wall: Reflecting on the Ethics and Effects of a Collective Critical Management Studies Identity Project. ’ Management Learning Vol. 39 Issue 1 p 57-72. EBSCOhost viewed September 25, 2008. ) Garrett, Michael. 2008. ‘What Will You Do When Your Desire to Please and Ethics Collide? ’ Business Source Complete, p 42-44, EBSCOhost viewed September 25, 2008. 3) Small, M. 2006, ‘A Case for Including Business Ethics and the Humanities in Management Programs’ Journal of Business Ethics, Vol. 64 Issue 2, p195-211, EBSCOhost viewed Se ptember 26, 2008 4) Tsahuridu, E. , & Vandekerckhove, W. 2008, ‘Organisational Whistleblowing Policies: Making Employees Responsible or Liable? ’ Journal of Business Ethics, Vol. 82 Issue 1, p107-118, EBSCOhost viewed September 26, 2008 5) Sohail, M. , & Cavill, S. 008, ‘Accountability to Prevent Corruption in Construction Projects’ Journal of Construction Engineering & Management, Vol. 134 Issue 9, p729-738, EBSCOhost viewed September 25, 2008 6) Annas, G. 2008, ‘Military Medical Ethics – Physician First, Last, Always’ New England Journal of Medicine, Vol. 359 Issue 11, p1087-1090. EBSCOhost viewed September 26, 2008 7) Swartz, N 2003, ‘Business Leaders Form Ethics Organization’, Information Management Journal, Vol. 37 Issue 2, p14. EBSCOhost, viewed September 23, 2008 8) Belsie, L 2002, ‘Watching for technology abuse at work’, Christian Science Monitor, Vol. 0, Issue 184, EBSCOhost, viewed 24 September 2008. 9 ) Strassmann, P 2000, ‘Practice ethical IT’, Computerworld, vol. 34, no. 14, EBSCOhost, viewed 24 September 2008. 10) Jane, R 2002, ‘Facing ethical dilemmas’, InfoWorld, vol. 20, no. 52/01, p. 73, EBSCOhost, viewed 26 September 2008. http://www. acm. org/about/code-of-ethics http://www. pmi. org/info/AP_PMICodeofEthics. pdf http://www. scu. edu/ethics/practicing/decision/framework. html http://www. cpsr. org/act/contest/4wi2 http://gbr. pepperdine. edu/052/itmatters. html http://www. misq. org/archivist/vol/no16/issue4/effyoz. pdf

A Note On Macro, Micro Evolution There Is Important For...

First off, when talk about macro, micro evolution there is much falsehood about these two words, but, understanding them is maybe the vital essential for comprehension the creation or development issue. Macroevolution alludes to major developmental changes after some time, the inception of new sorts of creatures from beforehand existing, yet distinctive, tribal sorts. On the other hand, Microevolution alludes to assortments inside of a given sort. Change happens inside of a gathering, however the relative is unmistakably of the same sort as the precursor. According to Berkeley.edu, â€Å"Macroevolution generally refers to evolution above the species level. So instead of focusing on an individual beetle species, a macroevolutionary lens might require that we zoom out on the tree of life, to assess the diversity of the entire beetle clade and its position on the tree.† Macroevolution includes the most amazing patterns and changes in development, for example, the beginning of warm-blooded animals and the radiation of blooming plants. Macro evolutionary examples are by and large what we see when we take a gander at the substantial scale history of life. It is not as a matter of course simple to see macro evolutionary history; there are no firsthand records to be perused. Rather, we reproduce the historical backdrop of life utilizing all accessible confirmation: geography, fossils, and living beings. 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Some Skills For Studying Psychology - 1185 Words

Some Skills for Studying Psychology (SSSP) (2) Mindfulness Video 1. The essence of Dan Harris’s personal message regarding mindfulness meditation is that meditation is good for the brain. It helps to tame the voices individuals hear in their mind. It is a good form of exercise for the brain and consents the brain to relax from everyday stressing thoughts. Blood pressure decreases and improves the immune system. 2. (a). In the book â€Å"The healing power of meditation: Leading experts on Buddhism, psychology, and medicine explore the health benefits of contemplative practice.†, in the â€Å"Chapter: Meditation and Neuroscience†, neuroscientist Sara Lazar shows results in her investigation in a MRI scan, which shows that the grey matter in the†¦show more content†¦It may change the effect the independent variable has on the dependent variable. (d). Retrospective measure: A measure in which the data collected was formed through the use of past events and the recollection of what had happened in the experiment. 2. The primary research question that the paper is attempting to investigate is whether or not going under training to prevent mind wandering will help the mind to focus on the task on hand. The paper is investigating whether external distractions may be reduced with the use of a mindfulness training course. It is exploring whether decreasing external distractions to keep the mind concentrated on a task may improve and enhance cognitive performance. 3. The primary hypothesis of this investigation is that through the decrease of mind wandering, performance in tests, Working Memory Capacity (WMC) and Graduate Record Examinations (GRE) will improve. When the mind is trained to focus on a task, it will lead to the improvement in the results in the academic ability tests, which signifies an improvement in cognitive capacity and performance. The independent variables in this experiment is the level of mindfulness training that is received. The dependent variables in this experiment are accuracy on verbal graduate record examinations (GRE), Working memory capacity, Probe-caught task-unrelated thoughts (TUT’s), Retrospective self-reported TUT’s during performance of the working memory capacity measure and self-caught