Networks Essays - Local Area Networks, IEEE Standards,

Networks Network, in computer science, techniques, physical connections, and computer programs used to link two or more computers. Network users are able to share files, printers, and other resources; send electronic messages; and run programs on other computers. A network has three layers of components: application software, network software, and network hardware. Application software consists of computer programs that interface with network users and permit the sharing of information, such as files, graphics, and video, and resources, such as printers and disks. One type of application software is called client-server. Client computers send requests for information or requests to use resources to other computers, called servers, that control data and applications. Another type of application software is called peer-to-peer. In a peer-to-peer network, computers send messages and requests directly to one another without a server intermediary. Network software consists of computer programs that establish protocols, or rules, for computers to talk to one another. These protocols are carried out by sending and receiving formatted instructions of data called packets. Protocols make logical connections between network applications, direct the movement of packets through the physical network, and minimize the possibility of collisions between packets sent at the same time. Network hardware is made up of the physical components that connect computers. Two important components are the transmission media that carry the computer's signals, typically on wires or fiber-optic cables, and the network adapter, which accesses the physical media that link computers, receives packets from network software, and transmits instructions and requests to other computers. Transmitted information is in the form of binary digits, or bits (1s and 0s), which the computer's electronic circuitry can process. Network Connections A network has two types of connections: physical connections that let computers directly transmit and receive signals and logical, or virtual, connections that allow computer applications, such as word processors, to exchange information. Physical connections are defined by the medium used to carry the signal, the geometric arrangement of the computers (topology), and the method used to share information. Logical connections are created by network protocols and allow data sharing between applications on different types of computers, such as an Apple Macintosh and an International Business Machines Corporation (IBM) personal computer (PC), in a network. Some logical connections use client-server application software and are primarily for file and printer sharing. The Transmission Control Protocol/Internet Protocol (TCP/IP) suite, originally developed by the United States Department of Defense, is the set of logical connections used by the Internet, the worldwide consortium of computer networks. TCP/IP, based on peer-to-peer application software, creates a connection between any two computers. Media The medium used to transmit information limits the speed of the network, the effective distance between computers, and the network topology. Copper wires and coaxial cable provide transmission speeds of a few thousand bits per second for long distances and about 100 million bits per second (Mbps) for short distances. Optical fibers carry 100 million to 1 billion bits of information per second over long distances. Topology Common topologies used to arrange computers in a network are point-to-point, bus, star, and ring. Point-to-point topology is the simplest, consisting of two connected computers. The bus topology is composed of a single link connected to many computers. All computers on this common connection receive all signals transmitted by any attached computer. The star topology connects many computers to a common hub computer. This hub can be passive, repeating any input to all computers similar to the bus topology, or it can be active, selectively switching inputs to specific destination computers. The ring topology uses multiple links to form a circle of computers. Each link carries information in one direction. Information moves around the ring in sequence from its source to its destination (see Computer Architecture). Local area networks (LANs), which connect computers separated by short distances, such as in an office or a university campus, commonly use bus, star, or ring topologies. Wide area networks (WANs), which connect distant equipment across the country or internationally, often use special leased telephone lines as point-to-point links. Sharing Information When computers share physical connections to transmit information packets, a set of Media Access Control (MAC) protocols are used to allow information to flow smoothly through the network. An efficient MAC protocol ensures

Alexander Graham Bell, Inventor of the Telephone

Alexander Graham Bell, Inventor of the Telephone Alexander Graham Bell (March 3, 1847–August 2, 1922) invented the telephone in 1876 when he was just 29 years old. Soon after, he formed the Bell Telephone Company. Bell could have easily been content with the success of his invention. His many laboratory notebooks demonstrate, however, that he was driven by a genuine and rare intellectual curiosity that kept him regularly searching, striving, and always wanting to learn more and to create.   He would continue to test out new ideas throughout a long and productive life. This included exploring the realm of communications as well as engaging in a wide variety of scientific pursuits that involved kites, airplanes, tetrahedral structures, sheep-breeding, artificial respiration, desalinization, water distillation, and even hydrofoils. Fast Facts: Alexander Graham Bell Known For: Inventing the telephoneBorn: March 3, 1847 in Edinburgh, ScotlandParents: Alexander Melville Bell, Eliza Grace Symonds BellDied: August 2, 1922 in  Nova Scotia, CanadaEducation: University of Edinburgh (1864), University College London (1868)Publications: A founding member of the  National Geographic Society, he helped launce Science magazineAwards and Honors: Albert Medal (1902), John Fritz Medal (1907), Elliott Cresson Medal (1912)Spouse: Mabel Hubbard  (m.  1877–1922)Children: Elsie May, Marian Hubbard, Edward, RobertNotable Quote: The inventor looks upon the world and is not contented with things as they are. He wants to improve whatever he sees, he wants to benefit the world; he is haunted by an idea. The spirit of invention possesses him, seeking materialization. Early Life Bell was born on March 3, 1847, to Alexander Melville and Eliza Symonds  in Edinburgh, Scotland. He was immersed in the study of sound from the beginning. His father, uncle, and grandfather were authorities on elocution and speech therapy for the deaf. It was understood that Bell would follow in the family footsteps after finishing college. However, after Bells two other brothers died of tuberculosis, Bell and his parents decided to immigrate to Canada in 1870. After a brief period living in Ontario, the Bells moved to Boston, where they established speech-therapy practices specializing in teaching deaf children to speak. One of Alexander Graham Bells pupils was a young Helen Keller, who when they met was not only blind and deaf but also unable to speak. In 1872, Bell met Boston attorney Gardiner Greene Hubbard, who would become one of his financial backers and his father-in-law. Bell began to court Hubbards daughter, Mabel, in 1873. They married in 1877. From Telegraph to Telephone The telegraph and telephone are both wire-based electrical systems, and Bells success with the telephone came as a direct result of his attempts to improve the telegraph. When he began experimenting with electrical signals, the telegraph had been an established means of communication for some 30 years. Although a highly successful system, the telegraph was basically limited to receiving and sending one message at a time. Bells extensive knowledge of the nature of sound and his understanding of music enabled him to conjecture the possibility of transmitting multiple messages over the same wire at the same time. Although the idea of a multiple telegraph had been in existence for some time, no one had been able to fabricate one- until Bell. His harmonic telegraph was based on the principle that several notes could be sent simultaneously along the same wire if the notes or signals differed in pitch. Talk With Electricity By October 1874, Bells research had progressed to the extent that he could inform his future father-in-law about the possibility of a multiple telegraph. Hubbard, who resented the absolute control then exerted by the Western Union Telegraph Company, instantly saw the potential for breaking such a monopoly and gave Bell the financial backing he needed. Bell proceeded with his work on the multiple telegraph, but he did not tell Hubbard that he and Thomas Watson, a young electrician whose services he had enlisted, were also developing a device that would transmit speech electrically. While Watson worked on the harmonic telegraph at the insistent urging of Hubbard and other backers, Bell secretly met in March 1875 with Joseph Henry, the respected director of the Smithsonian Institution, who listened to Bells ideas for a telephone and offered encouraging words. Spurred on by Henrys positive opinion, Bell and Watson continued their work. By June 1875, the goal of creating a device that would transmit speech electrically was about to be realized. They had proven that different tones would vary the strength of an electric current in a wire. To achieve success, they needed only to build a working transmitter with a membrane capable of varying electronic currents and a receiver that would reproduce these variations in audible frequencies. Mr. Watson, Come Here On June 2, 1875, while experimenting with his harmonic telegraph, Bell and Watson discovered that sound could be transmitted over a wire. It was a completely accidental discovery. Watson was trying to loosen a reed that had been wound around a transmitter when he plucked it by accident. The vibration produced by that gesture traveled along the wire into a second device in the other room where Bell was working. The twang Bell heard was all the inspiration that he and Watson needed to accelerate their work. They continued to work into the next year. Bell recounted the critical moment in his journal:   I then shouted into M [the mouthpiece] the following sentence: Mr. Watson, come here- I want to see you. To my delight, he came and declared that he had heard and understood what I said. Other Inventions Alexander Graham Bells curiosity also led him to speculate on the nature of heredity, initially among the deaf and later with sheep born with genetic mutations. He conducted sheep-breeding experiments at his estate to see if he can increase the numbers of twin and triplet births.   In other instances, it drove him to try to come up with novel solutions on the spot whenever problems arose. In 1881, he hastily constructed a metal detector as a way to try and locate a bullet lodged in President James Garfield after an assassination attempt. He would later improve this and produced a device called a telephone probe, which would make a telephone receiver click when it touched metal. And when Bells newborn son, Edward, died from respiratory problems, he responded by designing a metal vacuum jacket that would facilitate breathing. The apparatus was a forerunner of the iron lung used in the 1950s to aid polio victims. Other ideas he dabbled in included inventing the audiometer to detect minor hearing problems and conducting experiments with what today are called energy recycling and alternative fuels. Bell also worked on methods of removing salt from seawater. Flight Technology These interests may be considered minor activities compared to the time and effort he put into making advances in flight technology. By the 1890s, Bell had begun experimenting with propellers and kites, which led him to apply the concept of the tetrahedron (a solid figure with four triangular faces) to kite design as well as to create a new form of architecture.   In 1907, four years after the Wright Brothers first flew at Kitty Hawk, Bell formed the Aerial Experiment Association with Glenn Curtiss, William Casey Baldwin, Thomas Selfridge, and J.A.D. McCurdy, four young engineers with the common goal of creating airborne vehicles. By 1909, the group had produced four powered aircraft, the best of which, the Silver Dart, made a successful powered flight in Canada on February 23, 1909. Later Years and Death Bell spent the last decade of his life improving hydrofoil designs. In 1919, he and Casey Baldwin built a hydrofoil that set a world water-speed record that was not broken until 1963. Months before he died, Bell told a reporter, There cannot be mental atrophy in any person who continues to observe, to remember what he observes, and to seek answers for his unceasing hows and whys about things. Bell died on Aug. 2, 1922,  at his estate in Nova Scotia, Canada. Other Works and Legacy Although working with the deaf would remain Bells principal source of income, he continued to pursue his own studies of sound throughout his life. Bells unceasing scientific curiosity led to the  invention of the photophone, a device that allowed for the transmission of sound on a beam of light. Despite being known for his invention of the telephone, Bell regarded the photophone as the greatest invention I have ever made; greater than the telephone. The invention set the foundation upon which todays laser and fiber optic communication systems are founded, though it would take the development of several modern technologies to fully capitalize on this breakthrough. With the enormous technical and financial success of his telephone invention, Bells future was secure enough so that he could devote himself to other scientific interests. For example, in 1881, he used the $10,000 award for winning Frances Volta Prize to set up the Volta Laboratory in Washington, D.C. A believer in scientific teamwork, Bell worked with two associates: his cousin Chichester Bell and Charles Sumner Tainter, at the Volta Laboratory. Their experiments produced such major improvements in Thomas Edisons phonograph that it became commercially viable. After his first visit to Nova Scotia in 1885, Bell set up another laboratory there at his estate Beinn Bhreagh (pronounced Ben Vreeah), near Baddeck, where he would assemble other teams of bright young engineers to pursue new and exciting ideas heading into the future. Sources Vanderbilt, Tom. â€Å"A Brief History of the Telephone, From Alexander Graham Bell to the iPhone.†Ã‚  Slate Magazine, Slate, 15 May 2012.â€Å"The History of the Telephone.†Ã‚  Google Books.infoundiscoveredscotland.co.uk, Undiscovered Scotland: â€Å"Undiscovered Scotland: Alexander Graham Bell.†Ã‚  Scotfax: Religion in Scotland on Undiscovered Scotland.A Century of Lawmaking for a New Nation: U.S. Congressional Documents and Debates, 1774 - 1875: The Alexander Graham Bell Family Papers. Charles Magnus.

Econometrics Essay Example | Topics and Well Written Essays - 750 words

Econometrics - Essay Example The classical linear regression model is written such that the coefficients of the independent variables measure the sensitivities of the dependent variable on the independent variables. It is usually assumed that there is an error term which measures the unexplained variance of the dependent variable that is not accounted for by the independent variable. Therefore, only a proportion of the variance is explained by the regression analysis. c) Any particular normal distribution can be related to the normal distribution because the normality assumption allows us to perform statistical tests concerning the estimated parameters using the normal distribution and related tests involving chi-square, t-distributions and F-distributions. d) It is not appropriate to take natural logarithms of interest rates, expressed as percentages because natural logarithms of interest rates are taken to minimize autocorrelations and render the interest rates scale free. However, interest rates expressed as percentages are scale free and uncorrelated already and therefore there is no need to take natural logarithms again. e) The Durbin Watson statistic can be used to estimat... (http://pages.stern.nyu.edu/churvich/Forecasting/Handouts/DWTest.pdf) 2. a) Omitting a significant variable from a regression analysis overstates the marginal impact of other variables in the model. For example, lets consider the impact of education on earnings. This relationship can be written in the form of a regression model as follows: (1) (Greene, 2003: p. 9). The above regression neglects the possibility that most people have higher incomes when they are older than when they are young, regardless of their education. (Greene, 2003: p. 9). Thus overstates the marginal impact of education on earnings. If age and education are positively related, then the regression model will associate all the observed increases in income with increases in education. Therefore a better way to study the determinants of income is to include the effects of age in the regression as follows: (2) according to Greene (2003: p. 9) earnings tend to rise less rapidly in the later earning years than in the early ones. To accommodate this possibility, the above model can be extended as follows: (3) (Greene, 2003: p. 9). b). Regression analysis studies the relationship between two or more variables. One variable is considered independent while two or more variables are considered to be independent. (Anderson et al, 2005). The aim of the regression analysis is to measure how changes in the dependent variable are explained by changes in the independent variables. Including an insignificant variable as one of the independent variables may minimize the effects of the actual variable causing the variation in the independent variable. Like in the example above, if truly age is not a determinant of income as

Research Essay Example | Topics and Well Written Essays - 1250 words - 1

Research - Essay Example He also feels this especially towards Biff who he thinks was doing particularly well until he went on to campus and failed his mathematics and thus never finished it. The psychological context is also brought out by the fact that Willy’s family and friends feel that he is losing his sanity (Miller 15). Happy and Biff discuss the mental degradation of their father but do not bring this out to him since they feel that he would not accept what they are telling him, his wife Linda is also aware of his mental problems but won’t tell him either because she is trying to unite the family which already appears on the verge of splitting up. Willy’s problems do however show themselves when he gets into an argument with his boss Howard over the rejection of his application for a town job. Willy loses his temper over a trivial matter showing his volatility and the dangers of depression. Willy’s spiral into depression is also shown by his constant hallucinations. He con stantly hallucinates of his past years of success such as 1928 when he was driving a red Chevrolet (Miller 13) of having conversations with his older brother as well point to his dementia. The constant hallucinations are thought to be a defense mechanism for the harsh realities that he is facing and were to prevent the onset of full scale depression, this however is not avoided as at the end of the play he still succumbs to it and commits suicide. Several factors are responsible for this depression the most important being his denial of the reality that he is not as successful as he imagines himself to be, and that Biff was never the successful football player that he imagines himself to be The success that Biff had was instead a touchdown that he scored while in high school. Willy’s imagination of success is shown when he goes to confront Howard’s father about his sacking citing the time in 1928 when he earned an extremely large bonus, he defends himself towards his b oss by citing the time twenty years ago when he found financial success and this is what he uses as his defense to have himself reinstatedâ€Å". The play is set in 1949 showing that Willy’s peak are twenty years past and yet he still clings on to them to prevent his acknowledgement that he is not as successful as he dreams(Miller 82). The theme of unrealistic parental expectations is constantly shown in Willy who believes that his son Biff is a failure, he wants his son to take up a job as a salesman and constantly berates him for not, he keeps reminding him about his high school successes and clings on them as proof that Biff has potential. He also keeps pressuring Bill to marry as he says that he was popular with everybody both boys and girls but as Linda points out Biff is rough with women and so it is difficult for him to settle down (Miller 31). The relationship between Linda and Happy also show how her expectations of him are more than what he can be even when trying, she complains that Happy should be doing more with his life and yet Happy is constantly providing money for her and Willy to use to supplement his income. Happy also has motivation to succeed and wants to become the manager of his store however

Textiles and the Environment Green Essay Example for Free

Textiles and the Environment Green Essay Sustainable building design attempts to make it healthier, less wasteful, and with fewer impacts on the natural environment through building design, materials, and building operations. Sustainable design tries to maximize overall efficiency and energy efficiency as well. Nowadays, however, the meaning of â€Å"green/sustainable design† encompasses not only buildings but all industries. The idea of â€Å"green† or â€Å"sustainable† entered the mainstream and has attracted public attention. There are many reasons why that concept is entering the mainstream and catch the attention of people: global warming, rising energy cost, the growing awareness and liability costs associated with â€Å"contamination of nature†, declining oil reserves, and concerns about limited supply. Green/sustainable design is measured according to environmental, financial and social factors. As focusing on industrial development, humans have destroyed much of the nature. It is essential to accept that humans are dependent on the natural environment for their survival and wellbeing. According to Edwin Datschefski, consultant in environmental management and sustainable product design, green design have to meet the following requisites to achieve sustainability in terms of environmental aspects: all materials for manufacturing products have to be reusable, energy comes from renewable sources such as solar, wind and water power, no hazardous substances are emitted to the environment during manufacture and use, and the efficiency of product is improved by requiring 90% less materials, energy and water than the counterparts providing equivalent utility did in1990. Social sustainability is the ultimate goal of green design is creating and maintaining quality of life for people while financial and environmental factors are means to the end. Social sustainability concerns protecting the mental and physical health of members of the public, encouraging community, treating people fairy, and providing essential services. People in good condition easily can afford to develop and maintain a healthy society. Financial factor is important for two reasons: the majority of businesses will not pursue sustainability without profits and plenty promises quality of life. Unlike misconception, the goal of financial benefits can agree with the goals of environmental and social advantages. Well designed products maximize profitability and generate long term revenue by minimizing consumption of resources, using infinite energy, and meeting increasing eco-conscious consumers’ needs. The green labels give advantages to the ethical customers and sustainable product industries both. Green labels have been tagged in order to communicate information to consumers. The labels ensure that the certified products by authority do not cause the environmental damages during manufacture and use: shoppers can tell at a glance that the product is safe for the nature and themselves as well due to the green labels. The logos encourage the customers to purchase the labeled products even though the products are more expensive than equivalents. Many people are sceptical of unjustified claims of companies, but green labels are the best way for the companies to prove that these claims are justified. It is very effective marketing strategy among any promotion or advertising plans. On the contrary, overusing labels could make shoppers confused. There are a number of organizations issuing green labels over the world. Green labels can be found everywhere having various designs usually in green or blue to be known intuitively by consumers. However, they cannot be sure that the label is issued by a reliable organization, the certification is achieved properly, and the manufacturers keep working to the requirement. 2) What is an eco-friendly textile? Why support Eco Friendly textile? Many of the clothes we wear today are made from synthetic materials

technology :: essays research papers

Introduction Even now, customer relationship management (CRM) is in its growth stage. Until recently, diverse individuals defined this concept differently. As the name suggests, the primary focal point is placed on the customer. If a company develops better customer relationships, it also improves business processes as well as its profits. In general CRM, is a more efficient automated method used to connect and improve all areas of business to focus on creating more solid customer relationships (CRM Research Center, 2001). All forces are coupled together to save, improve, and acquire greater business to customer relationships. The most common areas of business that are positively affected include marketing, sales, and customer service strategies (Digital Consulting Institute, 2002; CRM Research Center, 2001). CRM helps create time efficiency and savings on both sides of the business spectrum. Through correct implementation and use of CRM solutions, companies gain a better understanding of their s trongest and weakest areas and how they can improve upon these. Therefore, customers gain better products and services from their businesses of choice. In order to achieve better insight on CRM, it is essential to consider all of its components. Analogous to other technologies, CRM has its goals, costs, implementation strategies, and success and failure stories. Goals   Ã‚  Ã‚  Ã‚  Ã‚  If successful, CRM can assist businesses with many customer-oriented processes. In general, companies will be able to offer better customer service. By keeping track of customer preferences, a company will have a better idea of what type of questions to expect (Bannan, 2001). Through well-organized call centers they can provide faster more intelligent solutions to customers' questions and complaints. Costs   Ã‚  Ã‚  Ã‚  Ã‚  CRM does not come without its costs, however, according to a recent survey conducted by The Data Warehousing Institute, nearly half of the people surveyed stated that their CRM project expenses were less than $500,000. This demonstrates that not all CRM implementation has to be costly. On the other hand, this survey also presented that quite a few participants had budgets of more than $10 million (CRM Research Center, 2001).

Requirements for Research Essay

Abstract This study entitled â€Å"Orange (Citrus Sinensis) Peelings Extract as an Alternative shoe Polish† aims to aims to determine if orange peeling oil extract be a good alternative for shoe polish specifically to answer the following questions (1) What specific properties of the shoe polish produced are present/ identified? (2) What are the physical properties of the orange peeling extract shoe polish as to texture, color, and odor? (3) Is there significant difference/s between the orange peeling extract and coconut oil shoe polish with that of the other commercially sold shoe polish in terms of: polish-ness, odor, and texture? The researcher then conducted a series of experiments to test the project. These processes are the extraction of oil from the orange peelings that would be then mixed with the coconut oil produced (cooked) from the coconut plant and the testing and comparing of the alternative shoe polish made with that of the commercially sold shoe polish. The test was conducted with the use of leather shoes as the test object. The results showed that the alternative shoe polish produced has almost the same qualities as to that of the commercially sold shoe polish in terms of its physical properties. The produced shoe polish made the shoes shine a little bit and produced a nice odor considering the natural scent of the orange oil which is added to the mixture. The researcher recommends  trying testing different ratios of each and seeing in what trial it produced the best shoe polish. Further reading about the project is also recommended to widen the scope of study and to produce an alternative shoe polish that would be of help in aiming for the alternative shoe polish with the nearest qualities with that of commercial shoe polish. Acknowledgement The researcher wish to extend her sincerest appreciation to the following people who helped make this research. They are the ones who helped and supported me in performing this research. First to our Project Adviser and Research Teacher, Ma’am Juliet Ilustre-Herreria for continuously guiding and helping me throughout the making of my investigatory project; asked some tricky questions and suggested some opinions that eventually helped a lot in making the project. Next, to my cousin, Sherwin Keith Saringan for helping me choose what project to make and giving some information that could be of great help. To my parents, Mr. and Mrs. Balcorta for me giving support and supplying the materials that would be needed for this project to be completed. To my classmates and friends for giving encouragement whenever I lose hope and most of all to the Lord, up above, for answering my prayers and continuously guiding me in doing this research. Without these people around me, my investigatory project entitled, Orange (Citrus sinensis) Peeling Extract as an Alternative Shoe Polish, won’t be finished.