The study a library Essay Example for Free

The study a library Essay 2. 1 Background of the study A library is organized for use and maintained by a public body, an institution, a corporation, or a private individual. Public and institutional collections and services may be intended for use by people who choose not to — or cannot afford to — purchase an extensive collection themselves, who need material no individual can reasonably be expected to have, or who require professional assistance with their research. In addition to providing materials, libraries also provide the services of librarians who are experts at finding and organizing information and at interpreting information needs. Libraries often provide quiet areas for studying, and they also often offer common areas to facilitate group study and collaboration. Libraries often provide public facilities for access to their electronic resources and the Internet. Modern libraries are increasingly being redefined as places to get unrestricted access to information in many formats and from many sources. They are extending services beyond the physical walls of a building, by providing material accessible by electronic means, and by providing the assistance of librarians in navigating and analyzing very large amounts of information with a variety of digital tools. Kalayaan National High School started when Mrs. Esmelita P. Ulangca, the principal of Bagong Silang High School, felt an urgent need of an annex school in order to accommodate the heavy influx of enrolment of students. In 1996, the construction of two(2) three-storey building with 9 classrooms each were constructed in Phase 10 Bagong Silang, Caloocan. The first enrollment commenced on May 21,1997 where the first batch of 1,450 first year enrollees and organized into 14 sections with 18 teaches from Bagong Silang High School. As classes went on another three-storey with 15 classrooms was also constructed, 300 second year and 212 third year students from Bagong Silang Hish School were transferred. Along with them were 8 teachers. The first inauguration of the said buildings was held February 6,1998. In June 29,1998, a Division Memorandum No. 97 s. 1998 was issued to inform the field that the establishment of Kalayaan National High School(formerly Bagong Silang National High School Annex) as per Republic Act No. 8644 entitled â€Å"An Act Establishing a National High School in Bagong Silang, Caloocan City to be known as Kalayaan National High School and Appropriating Funds Thereof, lapsed into law on May 30,1998. Library System is one of Transaction Processing System because it can process large records and data of the school and it is also use for library transactions like borrowing and returning books. In Computerized Library System, the data are kept accurate in order to lessen errors in listing of books and computation of penalties. Library System is also designed to perform the process involve in acquisition, cataloguing, and circulation of books in the library. The proponents intend to propose to develop A Computerized Library System for Kalayaan National High School to enhance the transactions of the current procedure of their library. 2. 2 Overview of the current System Borrowing For those who are new borrowers they will be given a library card and fill up all the informations needed. The students are allowed to borrow as many books as they want inside the library premises. Anyone who wishes to borrow a book must physically check by himself the book stored in the shelf to know if it is available, if it is he should bring it to the librarian together with his library card. If he wishes to borrow it for over night he must return it the following day(excluding Saturday and Sunday), if he fails to return it he will need to pay for penalty per overdue books which cost 1 peso per day; if the student fails to pay for the penalties his clearance will be hold. But if the borrower is a Faculty there is a logbook provided for them to write their name, title of the book, date borrowed, and date returned and he is allowed to borrow the book for the whole school year and return it before the school year ends, if he lost or damaged the book his clearance won’t be cleared. Returning For returning the book the borrower will return it to the librarian and find his Borrower’s Card then the librarian will check if it is returned on the right date if it is not the borrower must pay for his acquired penalty. For Faculty members they will give the book to the librarian to record it on the logbook for faculty’s borrowed book the date they returned it. For all the penalties for overdue books,damage books and return boooks they will pay it to the librarian. For overdue books the students should pay penalty per overdue books which cost 1 peso per day. For lost or damage books the students should pay for the price of the book or replace it with a new one. Reports The librarian anually submitting the library’s annual inventory report by checking the books manually in the library, the librarian should physically check the books on the shelves and match it on the list of their books thatthey have. The report was done using Microsoft Excel. 2. 3 Project Rationale The following will be the beneficiaries of this study: * School They will be able to provide better service to their students because of a more organized records and user-friendly library. This study will also uplift the image of school by providing an optimal use of new technology. * Librarian He will be able to monitor the books easily and provide a record of library transactions such as borrowing and returning of books. Generating of reports such as list of books, list of Borrowers, list of Borrowers with offense, list of Damage books, list of Lost books, list of borrowed books, list of returned books, Inventory of Book will be more faster and easy. * Borrowers They do not need to search manually for the books they wished to borrow and they could easily know the availability of the book. The borrowing process could be more faster than their current procedure. * Library The library could easily monitor the condition of their books as well as its availability and stocks, because on their current system the librarian should physically check the books on the shelves. Generation of reports such as list of books, list of Borrowers, list of Borrowers with offense, list of Damage books, list of Lost books, list of borrowed books, list of returned books, Inventory of Books will be easier and faster. They could manage and easily update their records and transactions. * Proponents They would enhance their programming skills and knowledge in developing a system. * Future Researchers They could use this as a referrence for their study and guide for improving this system.

Dominos History and Analysis

Dominos History and Analysis History of Dominos Dominos Pizza was brought to America by Italian immigrants in the 1800s and it grew in popularity as a pie of choice and rose to popularity hence necessitating the nee for Dominos chain to be created. The companys business model was its reliance on delivery (which was set at 30 minutes) and a focus on efficient and streamlined processes of taking pizza orders, preparing them and delivering them to consumers. With Dominos success on its pizza delivery time the company it appeared as though the company substituted quality service for quality product hence the decline in Dominos shares. Dominos crisis. With the success of Dominos, customers where also demanding more from their pizza maker, they wanted better tasting pizza that had flavour. From the material provided, it is evident that Dominos became comfortable in their position to recognized as the leader in Pizza delivery and did not carry out any market research in other to find ways to improve their product and guarantee customer satisfaction. Marketing research generally comprises of a product research in terms of market need that a business wants to satisfy as well as the size and characteristics of the market (new or old) by identifying consumer preferences and buying behavior. Another reason for the Dominos Crisis was that the 30 minutes delivery time was not uniform for every Dominos outlet. Depending on how big a Dominos shop service area was the 30 minutes delivery time worked perfectly, but where the area is large and considering other factors the timing was different. Attribute analysis Attribute analysis is the process of breaking down a problem, idea, or thing into component parts and then thinking about the attributes of the problem rather than the thing itself by taking into consideration the crucial aspects of a companys business model and turning it around (IAF, 2009). What this means is that with rising customer dissatisfaction which is evident not only through surveys, feedbacks and word of mouth. There was the need for the Pizza turnaround programme because as at 2009 Dominos quarter revenue had dropped by 6.5% and as such there was the need for a massive overhaul of the companies financial and operational parameters. What was considered in this regard is how great pizza could be made while still maintaining the unique selling point which was the timing (30 minutes delivery time). Attribute analysis was used by simply identifying key problems that had been collated through customers feedback. This feedback was put together and to ensure customer loyalty product was improved and this improvement saw a 65% increase in repeat purchase by customers (Worldwide 2017). By meeting the challenges head on the turn around team did a road show with their franchises introducing the new and improved pizza as well as carried out blind test road show. From the road show a number of customers preferred the new taste. The success of any new initiative by an organization is highly dependant on the involvement of every member of the team directly involved in the product. Attribute analysis helped Dominos identify specific areas that needed improvement and then the next step was to inform senior management team of the negative feedback they had received from customers and management team saw the need to immediately turn around their pizza operations. In general, this case points to the fact that for any brand to successfully transform itself to one capable of competing for customers with the competition, creating a strong position for future growth is reliant on customer feedback, continued effort to improve product offering and in taking feedbacks and customer suggestions seriously. Concept testing approaches in my opinion created an opportunity for customers to be aware of the various efforts been made by Dominos to satisfy them through new and improved products. This no doubt helped Dominos grow and position itself favourably in the hearts of its customers. References Australian food News, February 2015. Dominos attributes record profits to innovations and new initiatives. Retrieved from: http://www.ausfoodnews.com.au/2015/02/11/dominos-attributes-record-profits-to-innovations-and-new-initiatives.html. Accessed 13 January 2017. IAF methods database. October 2009. Attribute analysis. Retrieved from: http://www.iaf-methods.org/node/11163. Accessed 13 January 2017. Worldwide.com. February 2017. How Dominos repositioned itself from pizza delivery to mealtime solution. Retrieved from: http://iris-worldwide.com/news/how-dominos-repositioned-itself-from-pizza-delivery-to-mealtime-solution/. Accessed 13 January 2017.

Losses In Xlpe Insulated Cables Engineering Essay

Losses In Xlpe Insulated Cables Engineering Essay Power cables, mainly underground power cables form a bulk part of electrical power systems network. Accordingly, when medium voltage XLPE cables were first installed in the late 1960s, cable manufacturers and electric utilities expected them to perform reliably for 20 to 30 years. However, history has shown that these cables had high percentage of life losses whereby the service life of some of these cables was far shorter than expected. Many cables failed after only 10 to 15 years in service. The failure of XLPE cables was happened due to the aging process. Aging of XLPE cables is related to the temperature of the insulation. For XLPE cables, the normal maximum operating temperature is 90  °C. At this maximum value, the consumption rate of anti-oxidant has been calculated to afford a cable life of 30 years. Increasing the XLPE cables operating temperature will increase the rate which the anti-oxidant is used up. Subsequently, it will reduce the service life of XLPE cables. The rea ction follows the Arrhenius relationship which is an exponential function. From this, even a small increase in temperature, it will hence give significant impact on the aging process of XLPE cables. Once the anti-oxidant in the cables is used up, the cables will start to oxidize and become easily broken. Then, the cables will be subject to stress cracking and electrical failure at positions of mechanical stress. In addition, the presence of harmonics in power system causes a conductor to overheat. This overheating process makes the cable to increase in term of temperature to its insulation. Therefore, cable will soften and the mechanical performances will reduce which is called as premature aging. Thus, it is important to investigate the presence of harmonic in any electrical equipment. From this we could know the temperature due to the overheating process and evaluate the life losses of any associated cables. TABLE OF CONTENTS CHAPTER TITLE PAGE DECLARATION 1 ACKNOWLEDGEMENT 2 ABSTRACT 3 TABLE OF CONTENTS 4 1 INTRODUCTION 8 1.1 Background 8 1.2 Premature Aging due to Harmonic 9 1.3 Development of Power Cables 9 1.3.1 Oil-Impregnated Paper Power Cables 10 1.3.2 Solid-Dielectric-Extruded Power Cables 11 1.3.2.1 Technology of XLPE Cables 13 1.4 Losses in Power Cables 15 1.5 Objectives of Study 16 1.6 Scopes of study 17 2 LITERATURE REVIEW 18 2.1. Introduction 18 2.2. Power System Harmonics 18 2.2.1. Definition of Harmonics 19 2.2.2. Source of Harmonics 19 2.2.3. The Harm of Harmonic 20 2.2.4. Effects of Harmonics on Power System 21 2.2.4.1 Motors and Generators 21 2.2.4.2 Transformers 22 2.2.4.3 Power Cables 22 2.2.4.4 Capacitors 23 2.2.5. Economical Damage due to Harmonic Losses 23 2.3 Underground Power Cables 24 2.3.1 Gas-filled Cable 24 2.3.2 XLPE Cables 27 3 EVALUATION OF THE AGING COST DUE TO HARMONIC LOSSES IN XLPE CABLES 29 3.1 Introduction 29 3.1.1 Flowchart 30 3.2 Calculation of Losses 31 3.2.1 Resistance of the conductor 31 3.2.2 Skin Effect 32 3.2.3 Proximity Effect 33 3.2.4 Total Power Losses 33 3.2.4.1 Joule Losses 34 3.2.4.2 Dielectric losses 34 3.3 Probabilistic Evaluation of the Economical Damage due to Harmonic Losses 35 3.3.1 Expected Value of the Aging Cost due to Harmonic Losses 35 3.4 Conclusion 39 4 DATA, MODELLING AND ASSUMPTIONS 40 4.1 Data 40 4.2 Assumptions 41 5 RESULTS, ANALYSIS, AND DISCUSSIONS 42 5.1 Results 42 5.2 Discussions 45 6 CONCLUSIONS AND RECOMMENDATIONS 46 6.1 Expected result 46 6.2 Conclusions 47 6.3 Recommendations 47 REFERENCES 49 APPENDICES APPENDIX A 52 APPENDIX B 58 APPENDIX C 67 APPENDIX D 68 APPENDIX E 69 APPENDIX F 72 APPENDIX G 73 Background By means of the discovery of electricity in the early 19th Century, all countries in the world nowadays have virtually utilized electricity as a source of light and energy. This has led to the existence of distribution-transmission line system carrying current, even if at different voltages and transporting it over long distances till the end users or customers. For the distribution-transmission line system, engineers had thought critically in finding the suitable power cables for power system. Mainly, most of the bulk electrical energy generated from the generation centers is being transported to major load centers within a large geographical area by the transmission systems using overhead lines [1]. In the other words, the distribution system delivers the electrical energy from these load centers to customers who are within a smaller geographical area. For safety, reliability and aesthetics, the electric circuits used to transport energy to such customers are usually underground power cables, though this kind of arrangement is expensive but has more advantages than the overhead lines [2]. Over the years, high demand of reliable electricity power supply has led the electricity markets to be highly competitive. Electric utility companies now have to develop means of maintaining, enhance the safety and reliability of their expensive power system components to operate advantageously and meet the demands of their customers. One of power system component that constitutes a bulk part of the distribution and transmission line systems in urban areas is the underground power cable. For instance, in the United Kingdom there are about 93000 km of 11 kV cable and more than 13000 km of 33 kV [6]. In Malaysia with rush of development has led to increasing demands of electrical energy. Doing this, underground cable distribution is increasing significantly. It is estimated that there are about 180000 km of underground cables in Malaysia, forming about 80 % of the underground power distribution system. This shows that, the technology of underground power cables has grown up very fast by the time as the world is moving extremely in science and technology. However, lately the presence of harmonic in electrical energy systems is well known [3]. The harmonics are due to nonlinear loads such as static converter and can damage the system components [6]. In the case of the cables, harmonics can cause relevant additional losses in the conducting and in the insulating materials which cannot be neglected. From the economical point of view, the presence of harmonics can cause economical damage which increasing the operating costs and decreasing the useful life of the system components. The economical damage due to harmonic losses can be defined as the summation of the operating costs and the aging costs. As stated in [13], the operating costs are referred to the costs of the incremental energy losses caused by the harmonic flow in the component, where the term incremental means that these losses are superimposed to the ones at the fundamental while the aging costs are referred to the incremental investment costs caused by the premature aging of the components caused by the harmonic pollution. Premature Aging due to Harmonic Aging failures have become a major and urgent concern in many utilities since many power system components are approaching the turning point to the end of life. For the case of power cables, the premature aging occurs due to harmonic pollution. The harmonic flow can lead to additional heating in power cables. Subsequently, temperature will rise and premature aging may result. Development of Power Cables [1] Power cable technology had its beginnings in the 1880s when the need for power distribution cables became pressing. With urban growth, it became increasingly necessary to replace some of the overhead lines for power transmission and distribution system with underground cables. The illumination of the larger cities proceeded at such a rapid pace that under some circumstances it was impossible to accommodate the number and size of feeders required for distribution, using the overhead line system approach. In fact this situation deteriorated so notably in New York City that, in addition to the technical and aesthetic considerations, the overhead line system began to pose a safety hazard to the line workers themselves, the firemen, and the public. As a result, the city passed an ordinance law in 1884 requires removing the overhead line structures and replacing them with underground power cables. Similar laws and public pressure were applied in other cities, with the consequence that by the early 1900s, underground electrification via insulated cables was on its way to becoming a well-established practice [14]. A practical lead press was invented in 1879 and subsequently employed to manufacture 2kV cables for Vienna in 1885. During the same period, vulcanized rubber was used to produce cables on a commercial scale, although use of guttapercha had already been made as early as 1846. Impregnated-paper power cables were first put on the market in 1894 by Callender Cables of England, using impregnant mixtures of rosin oil, rosin and castor oil and only in 1918 were these replaced by mineral oils. In North America, impregnated-paper cables were first supplied by the Norwich Wire Company. Varnished cambric cables were introduced by the General Electric Company in 1902. The behavior of these cables with hightemperature was subsequently improved the addition of black asphalt. Some of the more common early solid and liquid insulating employed in various underground cable installations were natural rubber, gutta-percha, oil and wax, rosin and asphalt, jute, hemp, and cotton. In 1890, Ferranti developed the first oil-impregnated-paper power cable. By following their manufacture, his cables were installed in London in 1891 for 10 kV operations. In addition, the cables were made in 20 ft lengths as the total circuit was 30 miles in length about splicing joints were four required. Nevertheless, these cables performed so well that the last cable length was removed from service only in 1933. Cable installation continued to proceed at a rapid pace, so that by the turn of the 20th century many major cities throughout the world had many miles of underground power cables. For example, already by the end of 1909, the Commonwealth Edison Company in Chicago had 400 miles of underground cable operated in the voltage range between 9 to 20 kV. Montreal had some 4500 ft cir cuits of three-conductor cables installed in ducts under the Lachine canal for 25 kV operations; the same voltage was used for cable traversing the St. Lawrence River in 1906. With some experiences behind them, cable manufacturers were increasingly gaining confidence and during the St. Louis Exposition in 1904 power cables developed for voltages as high as 50 kV were put on display [14]. Oil-Impregnated Paper Power Cables [14] During the period prior to World War I, extensive use was made of oilimpregnated paper cables of the three-conductor belted type for voltages up to 25 kV. Due to non-uniform stress distribution in the cable construction, the belted cable proved to be highly partial discharge susceptible when attempts were made to extend the operating voltage range with larger wall thickness to approximately 35 kV, to meet the increased power demand following World War I [18]. This problem was resolved by shielding the individual conductors, using 3-mil-thick copper tapes. The outside of the shielded conductors was thus maintained at the same ground potential. Figure 1.3.1 Cross-section of an Oil-impregnated Paper Insulated Cable In addition, the belt insulation was replaced with a binder consisting of fabric tapes and strands of interwoven copper wire. The purpose of the latter was again to maintain the shields of the three cables at the same potential. Over the years, the conductor shapes of the three-conductor shielded paper insulated cables have evolved into three forms, namely circular, oval, and sectoral. In many utilities a substantial portion of the present-day distribution load is still carried at 35 kV via three-phase oil-impregnated paper belted cables, with the three conductors individually grounded. There is little inducement to replace these cables with solid extruded dielectric cables, whose outer diameter for an equivalent power rating would exceed that of the ducts accommodating the more compact threephase oil-paper belted cables. Moreover, the oil-paper belted cables have been characterized by remarkably long in-service lifetimes that often exceed 65 years. Belted cables with unshielded conductors are still deployed but only for working voltages equal to or less than 15 kV. With the individual conductors shielded, it was possible to extend the use of the three-phase belted cables for voltages as high as 69 kV, though on the average their application has been confined to voltages below 35 kV. The main reason for this upper limit has again been associated with the occurrence of partial discharges, which had in numerous instances led to the deterioration and failure of the dielectric at the elevated voltages. The partial discharges were found to take place in voids, which were formed either during the manufacturing process or during the load cycling while in service. Solid-Dielectric-Extruded Power Cables [1, 14] With the discovery of the hydrocarbon thermoplastic polyethylene (PE) in England in 1933, polyethylene became rapidly, the insulant of choice for RF coaxial cables. PE was first used as an insulant for power cables in the 1950s. In the mid 1960s, conventional PE became the material of choice for the rapidly expanding URD systems in the United States. It was known to be superior to butyl rubber for moisture resistance, and could be readily extruded. It was used with tape shields, which achieved their semi-conducting properties because of carbon black. By 1968, virtually all of the URD installations consisted of polyethylene-insulated medium voltage cables. The polyethylene was referred to as HMWPE; this simply meant that the insulation used had a very high average molecular weight. The higher the molecular weight, the better the electrical properties. The highest molecular weight PE that could be readily extruded was adopted. Jacketed construction was seldom employed at that time. Extruded thermoplastic shields were introduced between 1965 and 1975 leading both to easier processing and better reliability of the cable [19]. XLPE was first patented in 1959 for a filled compound and in 1963 for unfilled by Dr. Frank Precopio. It was not widely used because of the tremendous pressure to keep the cost of URD down near the cost of an overhead system. This higher cost was caused by the need for additives (cross linking agents) and the cost of manufacturing based on the need for massive, continuous vulcanizing (CV) tubes. EPR was introduced at about the same time. The significantly higher initial cost of these cables slowed their acceptance for utility purposes until the 1980s. The superior operating and allowable emergency temperatures of XLPE and EPR made them the choice for feeder cables in commercial and industrial applications. These materials do not melt and flow like HMWPE. The emergence of power distribution cables insulated with PE have replaced a significant portion of the oil-impregnated-paper insulated power cables used at operating voltages up to 35 kV. But lower voltage PILC cables are still being manufactured, due to their in-service longevity and reliability. In spite the long record of service and reliability of PILC cables, they are being gradually replaced by the less hygroscopic polymeric insulated cables, XLPE. XLPE cables have distinct advantages which are lighter weight, better electrical and thermal properties, less maintenance, and easier terminating and jointing procedure etc. Today, XLPE cables are being extensively used in many countries all over the world. In 1959, Japan and USA commercialized XLPE cables up to medium voltage rating. Since then a fast development of XLPE cables has taken place. Presently, XLPE cable of 500 kV class has been installed in Japan. The introduction of XLPE has increased the capability of polymeric insulated cables because of their higher temperature ratings. XLPE insulations perform well at elevated temperatures. Their normal operating temperature is about 90  °C and designed to withstand an emergency overload and short circuit ratings of 130  °C and 250  °C, respectively. Technology of XLPE Cables XLPE has become the most favored insulant. Germany, USA, Asian and Scandinavian countries have installed gigantic quantities of such cables. Japan has developed XLPE cables up to 500 kV which is the highest voltage rating of XLPE cables manufactured so far. The basic material for XLPE cable is polyethylene (PE). PE has very good electrical properties. However, its mechanical strength decreases significantly above 75  °C restricting its continuous operating temperature to 70  °C only. The improved thermal characteristics of PE are obtained by establishing a large number of cross-links between its liner molecular chains employing suitable techniques. The introduction of XLPE has increased the capability of polymeric insulated cables because of their higher temperature ratings. The processes for converting PE to XLPE are electron irradiation, chemical cross linking, and organic silane method. Electron irradiation is a slow process and it is difficult to ensure an even degree of cross linking throughout the thick insulation required for power cables. Therefore this process is usually restricted to thin insulation of 1 to 2 mm thickness only. Chemical cross linking process is the process by which cross-linking of PE is established using organic peroxide such as dicumyl peroxide (DCP) at high temperature in the range 250 to 350  °C and pressure 15-20 kg/cm2. This method is employed in the production of XLPE cables of all voltage range, from LV to EHV. Sioplas technique is a relatively new method of cross linking PE into XLPE. Cross linking is achieved by mixing suitable silane to PE and exposing this to ambient conditions. This method has the distinct advantage of lower capital expenditure as no special arrangements to maintain high pressure and temperature are required. But the process is very slow for thick insulation and hence restricted to low voltage and medium voltag e XLPE cables. The general construction of XLPE cable consists of copper or aluminium conductor, extruded layer of semi conducting material over conductor (for voltage class above 3.3 kV), extruded XLPE insulation, extruded layer of semi-conducting material (for cables of voltage rating above 3.3 kV), copper wire or tape as metallic screen, armour, inner sheath and outer sheath, usually made of PVC etc. Three core XLPE cables are generally used up to maximum 33 kV. Cables of 66 kV and above voltage rating are of single core construction. Figure 1.3.2 Solid dielectric extruded power cable [14] The manufacturing process of XLPE cables consists of mixing of PE with cross-linking agent (DCP) and antioxidants, extrusion of semiconducting layers and insulation over the conductor, crosslinking the PE compound in curing lines at high temperature and pressure and cooling the core to ambient temperature. All these processes are carried out in one step employing catenaries lines for curing and cooling, hence the name continuous catenaries vulcanization. Semiconducting layers and insulation are extruded using triple extrusion technique. The curing process was initially carried out with steam at high temperature and pressure. This resulted in the formation of microvoids within the insulation and restricted the application of steam curing process up to 33 kV. To achieve reliable HV cables, it was therefore necessary to employ curing in the absence of steam. For this reason, dry curing methods were developed, where PE was crosslinked under nitrogen pressure in silicone oil, in molten salt and also in long dies. The numbers of microvoids were drastically reduced. A new curing process has recently appeared namely silane process which is more economical. Losses in Power Cables Losses in power cables include losses in conductor, insulation, sheath, and screens armors. Conductor losses (I2Rac losses) depend upon the rms current I effective AC resistance of the cable conductor. Dielectric losses comprise of losses due to leakage through the cable insulation and caused by dielectric polarization under AC stresses. It includes the net dielectric losses depend upon cable voltage, its frequency as well as the permittivity and loss tangent of the cable dielectric material, as shown by the equation below: Power loss = à Ã¢â‚¬ °CoV2ÃŽÂ µr tan ÃŽÂ ´ [2] (1) Generally, tan ÃŽÂ ´, which partially controls the dielectric losses, is significantly higher for oil-paper insulation as compared to XLPE insulation. For most of the dielectric materials used in cables, tan ÃŽÂ ´ depends upon temperature, applied stress and supply frequency. For oil-paper insulation tan ÃŽÂ ´ is also strongly influenced by moisture content. Therefore, in voltage cables, a moisture level of less than 0.05 % is desirable in order keep dielectric losses within acceptable limits. The presence of voids and microcracks can also influence dielectric losses. These voids are formed in the insulation or at the screens/insulation interfaces during manufacture, installation or operation. In polymeric cables, they are formed during the extrusion process while in paper-insulated cables, during the impregnation cycle. Voids may also form in cables by the differential expansion contraction of cable materials due to cyclic loading or short circuit conditions. These voids have a higher electric stress as compared to the bulk insulation. However, the gas inside a void usually has lower breakdown strength as compared to the main insulation. When the electric stress in void exceeds the breakdown strength of gas within the void, PD occurs. Any partial discharge in such voids increases the effective tan ÃŽÂ ´ value for insulation. Consequently, when the applied voltage is raised above the charge inception threshold, the dielectric losses exhibit a distinct increase. Similarly, impurities in the cable insulation and screening materials also increase dielectric losses. The AC current flowing along each cable conductor induces emf the metallic sheaths of the cable. Without grounding, such sheaths would operate at a potential above the ground potential and can pose a hazard. Furthermore, it will accelerate degradation of the jacket and materials, thereby affecting the cables life and reliability. When the sheaths are bonded, circulating current flows in them causing power losses. However, for three-core cables such losses are negligible. In addition to circulating currents, eddy currents are also induced in sheaths of both single and multi-core cables causing additional losses which usually are of small magnitudes. 1.5 Objectives of Study This project is conducted to evaluate the expected value of aging cost due to harmonic losses in XLPE cables. Therefore, this project is conducted regarding to these objectives: To investigate the effects of harmonics losses on XLPE cables from economical point of view. To evaluate the expected value of the aging cost due to harmonics losses in XLPE insulated cables. 1.6 Scope of study This study will focus on XLPE insulated cables This study will use the characteristics of single core underground cables. The effect of harmonics losses on XLPE cable will be investigated A program will be developed to evaluate the expected value of aging cost due to harmonic losses. The economical damage due to harmonic losses is quantified by means of the expected values of the operating costs and of the aging costs. For this, it will focus only for the calculation of the expected values of the aging costs. CHAPTER 2 LITERATURE REVIEW 2.1 Introduction We design power systems to function at the fundamental frequency [1]. In Malaysia, the fundamental frequency is standardized at 50 Hz. This design is prone to unsatisfactory operation. At the same time, failure will happen when subjected to voltages and currents those contain substantial harmonic frequency elements. Frequently, the electrical equipment may seem operate normally. However, when they operate under a certain combination of conditions it might enhance the impact of harmonics which cause results to damage [20]. Most people do not realize that harmonics have been around for a long time. Since the first AC generator began to operate more than 100 years ago (Sankaran, C., 1995), electrical power systems have experienced harmonics. When harmonics present in electrical equipment, it can cause the equipment to malfunction and fail to work. In this case proper design and rating are needed to prevent the presence of harmonics. 2.2 Power System Harmonics The objective of the electric utility is to deliver sinusoidal voltage at fairly constant magnitude throughout their system. In fact, in order to achieve this objective is reasonably complicated because there are loads that exist on the power system that will produce harmonic currents. These currents produced may result in distorted voltages and currents that can give negative impact to the system performance in different ways. As the number of harmonic producing loads has increased over the years, it has become increasingly necessary to address their influence when making any addition or changes to an installation. We should consider two important concepts that have to bear in mind with regard to power system harmonics. The first concept is the nature of harmonic current producing loads (non linear loads) and the second concept is the way in which harmonic currents flow and how the resulting harmonic voltages develop. Ideally, voltage and current waveforms are perfect sinusoids. However, because of the increased popularity of electronic and other non-linear loads, these waveforms quite often become distorted. This deviation from a perfect sine wave can be represented by harmonics sinusoidal components having a frequency that is an integral multiple of the fundamental frequency. Thus, a pure voltage or current sine wave has no distortion and no harmonics, and a non-sinusoidal wave has distortion and harmonics. To quantify the distortion, the term total harmonic distortion (THD) is used. The term expresses the distortion as a percentage of the fundamental (pure sine) of voltage and current waveforms. In addition, current harmonics can distort the voltage waveform and cause voltage harmonics. Voltage distortion affects not only sensitive electronic loads but also electric motors and capacitor banks. 2.2.1 Definition of Harmonic Harmonics are defined as current and voltages at frequencies that are integer multiples of the fundamental power frequency [4]. For example, if the fundamental frequency is 50 Hz, then the second harmonic is 100 Hz, the third is 150 Hz, and etc [5]. The presence of harmonics in electrical energy systems is well recognized due to nonlinear loads such as static converters and it can damage the system components [6]. These nonlinear loads will draw current in abrupt pulses rather than in a smooth sinusoidal manner. Then, these pulses cause distorted current wave shapes which in turn and cause harmonic currents to flow back into other parts of the power system. In the case of power cables, harmonics can cause relevant additional losses in the conducting and in the insulating materials which cannot be neglected in the cable size [6]. 2.2.2 Source of harmonics Most harmonics originate from the generation of harmonic current caused by nonlinear load signatures [4]. The major sources of power system harmonics include switching operations, power electronic devices and other nonlinear loads and etc [7]. Electronic devices are nonlinear and thus they create distorted currents even when supplied with a purely sinusoidal voltage. As nonlinear currents flow through a facilitys electrical system and the distribution-transmission lines, additional voltage distortions are produced due to the impedance associated with the electrical network. Thus, as electrical power is generated, distributed, and utilized, voltage and current waveform distortions are produced [8]. As the number and ratings of power electronic devices connected to the power systems increase, the harmonic currents injected into power system and the resulting voltage distortions have become a major problem for power quality. This is the current issues that always be taken into account nowadays. Furthermore, the installation of power factor improving capacitors may lead to resonance conditions that amplify specific harmonic currents flowing into transformers and generators. On the other hand, large industrial ac motors may also provide a path for the harmonic currents. These currents can cause overheating problems for the motors, generators, and transformers. Power grid connected electric devices which can generate harmonic currents in the power system include fluorescent light ballast transformers, induction motors, incandescent light dimmers, overexcited transformers, arc welding equipment, AC/DC rotary converters, battery chargers, computers, and any type of device that utilize s rectified AC power to drive DC equipment [9]. 2.2.3 The Harm of Harmonics Harmonics only mean trouble if the power system is not well designed to handle them. High harmonic neutral currents are a problem only if the neutral is not properly sized. Current harmonics are not a problem to a transformer if it is derated appropriately. Even some voltage distortion below 8 % THD at the point of utilization is acceptable as long as sensitive equipment is not affected. However, it is always important to be aware of the presence of harmonics and to try to minimize them by purchasing low distortion electronic ballasts and reactors for PWM ASDs. This will not only keep the harmonics in check and improve the power factor in the facility, but will also save energy by reducing losses on power system components. In addition, any time there is a considerable increase of non-linear loads, it is important to check power system components to prevent problems. 2.2.4 Effects of Harmonics on Power System Harmonic currents and voltage distortion are becoming the most severe and complex electrical challenge for th

touch senses :: essays research papers

The skin contains numerous sensory receptors which receive information from the outside environment. The sensory receptors of the skin are concerned with at least five different senses: pain, heat, cold, touch, and pressure. The five are usually grouped together as the single sense of touch in the classification of the five senses of the whole human body. The sensory receptors vary greatly in terms of structure. For example, while pain receptors are simply unmyelinated terminal branches of neurons, touch receptors form neuronal fiber nets around the base of hairs and deep pressure receptors consist of nerve endings encapsulated by specialized connective tissues. Receptors also vary in terms of abundance relative to each other. For example, there are far more pain receptors than cold receptors in the body. Finally, receptors vary in terms of the concentration of their distribution over the surface of the body, the fingertips having far more touch receptors than the skin of the back. Other types of receptors located throughout the whole body, including proprioceptive receptors and visceral receptors, receive information about the body's internal environment. Proprioceptive or stretch receptors, located in muscles and tendons, sense changes in the length and tension of muscles and tendons and help to inform the central nervous system of the position and movement of the various parts of the body. Each stretch receptor consists of specialized muscle fibers and the terminal branches of sensor neurons. The muscle fibers and sensor neuron endings are very closely associated and are encased in a sheath of connective tissue. Visceral receptors monitor the conditions of the internal organs. Most responses to their stimulation by an organ are carried out by the autonomic system. Several visceral sensors, however, produce conscious sensations such as nausea, thirst, and hunger. Touch Receptors are the nerves cells that tell your brain about tactile sensations. There are several types of touch receptors, but they can be divided into two groups. Mechanoreceptors that give the sensations of pushing, pulling or movement, and thermoreceptors that tell you about sensations of temperature. The mechanoreceptors contain the most types of touch receptors. Free nerve endings inform the brain about pain, and they are located over the entire body. Located in the deep layers of dermis in both hairy and glabrous skin, the pacinian corpuscles detect pressure, telling the brain when a limb has moved. After the brain has told a limb, such as an arm, to move, the pacinian corpuscles tells the brain that that limb has actually moved into the correct position. touch senses :: essays research papers The skin contains numerous sensory receptors which receive information from the outside environment. The sensory receptors of the skin are concerned with at least five different senses: pain, heat, cold, touch, and pressure. The five are usually grouped together as the single sense of touch in the classification of the five senses of the whole human body. The sensory receptors vary greatly in terms of structure. For example, while pain receptors are simply unmyelinated terminal branches of neurons, touch receptors form neuronal fiber nets around the base of hairs and deep pressure receptors consist of nerve endings encapsulated by specialized connective tissues. Receptors also vary in terms of abundance relative to each other. For example, there are far more pain receptors than cold receptors in the body. Finally, receptors vary in terms of the concentration of their distribution over the surface of the body, the fingertips having far more touch receptors than the skin of the back. Other types of receptors located throughout the whole body, including proprioceptive receptors and visceral receptors, receive information about the body's internal environment. Proprioceptive or stretch receptors, located in muscles and tendons, sense changes in the length and tension of muscles and tendons and help to inform the central nervous system of the position and movement of the various parts of the body. Each stretch receptor consists of specialized muscle fibers and the terminal branches of sensor neurons. The muscle fibers and sensor neuron endings are very closely associated and are encased in a sheath of connective tissue. Visceral receptors monitor the conditions of the internal organs. Most responses to their stimulation by an organ are carried out by the autonomic system. Several visceral sensors, however, produce conscious sensations such as nausea, thirst, and hunger. Touch Receptors are the nerves cells that tell your brain about tactile sensations. There are several types of touch receptors, but they can be divided into two groups. Mechanoreceptors that give the sensations of pushing, pulling or movement, and thermoreceptors that tell you about sensations of temperature. The mechanoreceptors contain the most types of touch receptors. Free nerve endings inform the brain about pain, and they are located over the entire body. Located in the deep layers of dermis in both hairy and glabrous skin, the pacinian corpuscles detect pressure, telling the brain when a limb has moved. After the brain has told a limb, such as an arm, to move, the pacinian corpuscles tells the brain that that limb has actually moved into the correct position.

Gender Emergence in England’s History Essay -- European History

Gender Emergence in England’s History "Historicizing Patriarchy: The Emergence of Gender Difference in England, 1660-1760" by Michael McKeon is a powerful and original hypothesis as to "how and why the modern system of gender difference was established during the English Restoration and eighteenth century" (295). McKeon, a professor of English literature at Rutgers University is also the author of several essays, including "Politics and Poetry in Restoration England" and "Origins of the English Novel." McKeon uses the term 'patriarchalism' because it attaches itself to a "traditional regime" which will in later centuries be replaced by the "modern conception of gender" (296). This term is mainly identified with as traditional because it is not normally questioned nor objected to; people interpret it as the natural order of things. McKeon's patriarchal system is founded on the belief that there was a "hierarchical notion of authority" which existed not only in Britain's government, but in the family as well. The oldest male figure of the household was most often looked upon as the leader; he simultaneously played the roles of father, husband, and ruler of the house. His word was absolute law for the family. As with most issues, there are two sides. Parliamentarian Henry Parker and feminist Mary Astell disagreed on many issues, including whether the family and state were both founded on the concept of absolute power. However, they both agree on the "continued plausibility of the analogy between family and state" (297). So, although many critics do not feel comfortable with absolute power being the ruling force of family and state, they do agree that there is a direct correlation between them. Debates continued until arou... ...es embraced it sooner than others. The ideology and rationale are there, yet this change has many exceptions and abstractions which will not allow historians to fully confirm their thesis. There are many overlapping levels of experience, class, and gender that encompass a broad sexual, political, economic, cultural, and intellectual range. A good metaphor that McKeon uses throughout the essay to compare gender to a web from which other lifestyles stem. McKeon cleverly sums up his argument by stating that "it is therefore a determinant regime in that it establishes the outer limits of our experience, and it is under the aegis of difference that we formulate our efforts to go beyond it" (316). Works Cited McKeon, Michael. "Historicizing Patriarchy: The Emergence of Gender Difference in England, 1660-1760." Eighteenth-Century Studies vol. 28, no. 3, 1995: 295-322.

Islamic civilization Essay

Islamic civilization which known as golden ages has a lot of contribution in mordent civilization. Islam is a religion which belief in one god Allah also encourages to gain knowledge from the creation of Allah. The last messenger of Islam Muhammad (May peace be upon him) advice his follower to seek knowledge. Islamic scientist and scholar had contributed a lots in mordent science starting from the medical science , mathematics , architecture , philosophy geography etc. from the two documentary â€Å" Islam and science† made by BBC and â€Å"short film about 1001 invention† which described the contributions of Islamic civilization in the mordent world. First of all talk about the contribution of Islamic scholar in mathematics. The language of modern science still has many references to Arabic roots. If we discuss about scientific terms like Algebra, Algoriddim, alkaline this word as Arabic. There will be no mathematic or no physics without Algebra, no computer without Algoriddim, no chemistry without alkaline. Surprisingly few people in the west today even scientist are aware of this medieval Islamic legacy. But it was not always so, from 12th to 17th century European scientism and scholars regularly refers to earlier Islamic text. European world realize that there way of doing arithmetic which is essentially based on Roman numerals which was hopelessly inefficient. Muhammad ibn-musa al-khwarizmi showed Europeans a batter way to doing arithmetic. In his book the Hindu Art of Reckoning he describes a revolutionary idea. He shows that we can represent any number we like with just ten simple symbols. Which are Indian Arabic digits or symbols Ù ¡Ã¢â‚¬Å½ to Ù © and Ù  Ã¢â‚¬Å½ and in English 1 to 9 and 0, by using this now we represent all the number we like. Al-Khwarizmi created the decimal points at time of translating Indian system to Arabic. By using this decimal now we can describe the fraction numbers not only the whole numbers. Islam always encourage to gain knowledge, prophet Muhammad Sallallaahu alayhi wa sallam, (May peace be upon him), advice his followers to seek knowledge. Abd al-Malik ibn Marwan one of the leader of Islamic empire 8th century (AD) select one common language Arabic to rule the Islamic empire. Selecting common language is not only for administrative connivance. He realizes the important to gain knowledge. As a result Abd Al Malik start collecting different books from other reason as, Greek, Persian and bring those books and translate to Arabic, this became known as  translation period. To collect books Abd Al Malik send his messengers different part of the world and anyone who brought a book that he did not have , he repaid that person by its weight in gold. As a result of translation movement scholars, scientist, physicians in Arab empire was familiar or aware of the latest remedies, innovation, theories introduced by the other scholar from the far away as India and china. The golden ages of Islam which is time between 8th century to 1258 when Mongol conquest of Bagdad. Through scholars and scientist of various faiths some of the most important discoveries known to man were invented in this time. Starting from the Islamic scholar Ibn sina , Al Zahrawi in medical science to Al Biruni who determined the size of the world. Al Rayhan Al Biruni successfully determined the size of the world by using his formula or method. To estimate the size of the world Al Biruni used the height of the mountain and the angle of dip of the flat horizon from the mountain. Ibn al-Haytham , whose idea led to the invention of camera. By explaining who our eyes work Ibn Haytham led the foundation for modern cameras. Abbas Ibn Firnas who is the first man in the history who believed that man can fly before many years before the Wright brother. On the other hand, not only the male scholar contributed or invented new technology in this golden ages. Beside all the male Islamic schola r there was a lots of female scholar contributed a lot by inventing new technology this period. Merriam Al Astrulabi, she invented sophisticated astrolabes which show the sky and the stars on a small flat plate. This used by the navigators, astrologers astronomers for predicting the position of the stars, sun, moon etc. Abu-Ali Husayn Ibn-abdullah Ibn-sina one of the greatest Islamic scholar. In 1025 he completed Al-Qanon fi Al-Tibb (canon of medicine) in it he collected and expanded all that gone before him, medical idea from Greek to India and turns them into a single work. In this book he describe how human body works, how disease work in general, what are the causes for different disease. Another great scholar in Islamic empire is Abu Al Qasim Al Zahrawi , known as greatest medieval surgeon. Abu Al Qasim Al Zahrawi well has known for his book Al Tasrif and inventing several surgical instruments, which still use in the mordent medical science. In his book Al Tasrif which consists thirty parts and he describe different issues in medical science.  The most important part Fro m his book Al Tasrif where he describe different surgical treatment which include surgery of eye ,ear , removal of stone from bladder etc. In conclusion, at the time of golden ages in Islamic civilization the scholar and scantiest in Islam contributed to science in a large extent. Which gave new theories, methods, scientific innovation in different field. Starting introduce new way to calculate the numbers, inventing instruments for doing surgery, who our boy work and cause of different diseases, determining the size of the world so on. Most of this theories and inventions are still using in the modern science. On the other hand translation period provide a great opportunity for the Islamic scientist to gain knowledge and use that knowledge to invent a new ideas.

The Positive and Negative Impacts of Technology on Family Life

The Positive and Negative Impacts of Technology on Family Life â€Å"Is technology tearing apart family life? Text messaging, social networking, and online video are changing the way parents and children see the world—and each other. † There are many technologies in today’s world that are widely used not just as a want, but as a necessity of life. This term paper will focus on relationship between family life and computer technologies, which have become the most widely used technology in the world due to its variety of functions including SNS, mailing, online face-to-face video chatting, and assignment completing tools. Computer technologies have both positive and negative effects on family life. As more and more families are beginning to own their own computers (computer internet users in North America reached to about â€Å"78. 3 %†) , the effects of technologies on family life is becoming more easily identifiable. This term paper will come across both the benefit and negative effects of using technologies on family life. There are the negative effects which include the isolation of family members, and parents bringing their work home. On the other hand, linking relatives together is one positive effect that technologies have on family life, and being instantly updated on other family members’ status is also a huge benefit. Overall, the benefits of using technologies outweigh the negative effects. One negative effect of computers on family life is less face-to-face contact between family members. In most families, each family member has their own computers or smart phones that are kept in their own rooms. Nowadays, the functions of computers and smart phones are not just limited to internet surfing, and assignment tools. They are also widely used for social networking services (SNS), such as; Facebook, Skype, and Twitter just to name a few. As a result of the increasing time consumption of using the functions on computers, family members are now more isolated from each other and cannot talk to each other face to face as often as before when technologies were not as important in day to day living. Even when there is only one computer per family, there is an interruption with family life. If one person is using the computer, then other family members do not want to just wait while the computer is being used, so they will go to a different room and each person will end up using the computers at their own leisure. The use of computer games is another thing that has reduced human contact between family members. Before computers were used in the home, if someone wanted to play a game, they usually had to find at least one other family member to play a board game or card game with them. That forced families to spend more time talking to each other. Now if someone wants to play a game that requires more than one person, they can just go on the computer and either play online against another person, or they can play against the computer. Playing games on the computer makes it easier to be isolated from physical contact with other family members. Now that you don’t have to ask person in your family to play a game, most families don’t spend as much time talking to each other and learning about each other. Another negative cause that computers have on family life is that many people now bring their work home with them instead of leaving it at work the way they used to. People’s work is now invading the privacy of their home. People find that it is easier and more convenient to work at home, so they bring their work home allowing it to invade their home. When people bring home their work, it separates families by causing parents to spend more time at home working, and less time with their family causing parents to not know as much about what is going on in their children’s lives. Bringing work home separates families, making them not as close knit as they would be if they spent more time together talking. Computer technologies have not just had negative effects on families; they have also had some positive ones. The use of Social Networking Service (SNS) through computer is one of the positive effects that technologies have had on families. With the use of computer functions such as; e-mail, Messengers, Twitter, and Skype, families can take care of things that they would otherwise have to leave the home to take care of. Using SNS also allow families to communicate with other family members who might not live close by. For example, I Skype (free online webcam chatting) my father in Korea at least twice a week. Without the use of SNS I wouldn’t be able to communicate with him nearly as much because phone bills would be too expensive for me to afford. So, because of SNS I am able to remain close to my father even though he is in Korea, and I am in Canada. A second positive effect that technologies have had on families is the use of instant texting service. This allows families to talk to each other and have a fairly normal conversation with each other even though they might not be in the vicinity. I personally use instant text messaging services to talk to my parents, my sister, and my relatives regularly because it keeps them updated on what is happening with me on a daily basis. While I am at school, I am still able to stay in touch with everyone back home without having to call each one of them separately. For many people who are away at school, instant texting services allow them to stay in touch with friends and family even though they are not at home. A third positive effect that technologies have had on families is computer web pages (Facebook). Web pages allow families to post pictures of themselves and other family members so that everyone in the family can go to the web page and view the pictures. My sister has a web page that explains things about her, and it has pictures of her and friends. One of my other uncles who lives in Korea also has his own web page. On his web page, he has pictures of his baby daughter. By going to my uncle’s web page, I have been able to see pictures of my baby cousin as she has grown and changed. Many other families have web pages similar to my families that they use to watch their families change even though they are not in the same country. In conclusion, the negative effects of using technologies posed can essentially be overcome by use of SNS technology through computer or phone. When there is lack of human contact between the family members, then Skype can be used to perform online face-to-face chatting. The use of technologies also proved to be more efficient when each family member want to be updated on each others’ status. Without the use of technology, instant messaging system would not be possible, so the relatives or family members would not be able to interact with each other as easily. APA 6th edition reference 1. Miniwatts Marketing Group (MARCH 31, 2011). WORLD INTERNET USAGE AND POPULATION STATISTICS. Retrieved from http://www. internetworldstats. com/stats. htm 2. Chris Barylick (June 21, 2001). Technology and Social Isolation. Retrieved from http://www. irchelp. org/irchelp/misc/tech. html 3. Gary Small, M. D. (June 19, 2009). Is Technology Fracturing Your Family. Retrieved from http://www. psychologytoday. com/blog/brain-bootcamp/200906/is-technology-fracturing-your-family.