Abstract This paper analyzes the efficiency of the access algorithms in IEEE 802.11 infrastructure wireless LANs. The first part of the paper provides an overview of the access algorithms that are in used in IEEE 802.11 implementations. A mathematical model of the carrier sense protocols is introduced and analyzed through the second part. The main part of the paper is devoted to simulation of IEEE 802.11 infrastructure networks. For this purpose a discrete event simulator has been designed and implemented. Finally the results are presented and discussed.
Table of Contents
IEEE 802.11 Wireless LANS
IEEE 802.11 Access Algorithms
Mathematical Analysis of the Carrier Sense Protocols
Non-Slotted Non-Persistent CSMA
Slotted Non-Persistent CSMA
Simulation of IEEE 802.11 Infrastructure WLANS
Traffic Modeling
The Simulation Model
Simulation Results
Summary
References
The Simulator Source Codes
From the Paper "Nowadays, wireless LANs, also known as WLANs, are used widely as an alternative for the wired LANs. In Comparison with the traditional wired LANs, WLANs provide more flexibility and higher ROI (Return On Investment) for both providers and customers. Also in some cases (such as disaster discovery), it is impossible to set up a wired LAN. Since setting up a WLAN does not need a great starting investment (especially in the case of ad hoc operation), it is considered to be an ideal choice for any temporary network connectivity requirement in local scales. For these reasons, the WLAN's productivity has increased rapidly during recent years."
Abstract This paper discusses the genetic engineering field of reprogenetics. It covers the history and overview of biotechnology, reprogenetics current practices (from IVF to amniocentesis and chorionic villus sampling) as well as potential future possibilities as well as bioethics and its implications on society.
Outline
Introduction
Biotechnology: Overview and History
Introduction to Reprogenetics
Current Practices of Reprogenetics
The Future of Reprogenetics
Bioethics
Conclusion
From the Paper "The future of Reprogenetics is based around Genetic Engineering of the Germline (Silver, 2000). This essentially refers to the art of modifying or adding to, the embryo, any gene imaginable and any number of genes. Genetic Engineering of the Germline would allow parents to basically design their offspring, from physical characteristics to mental capacity, realising the concept of 'designer babies'. This technology has been used with increasing efficiency on mice, pigs and sheep. However, not until recently has it been considered possible to apply it to humans. This was largely due to quite a low success rate combined with ethical questions. Powerful new modification and screening technologies could allow scientists to overcome this low success rate. The question of ethics however, may remain indefinitely."
Abstract This paper states that quality in construction is the goal of every dedicated worker involved in any construction project. The paper contends that many factors pose a risk to the overall quality of construction. The paper examines two of the major problems facing the construction industry today, inferior materials and a shortage of skilled workers. The paper claims the necessity of comprehensive programs to be put into place to ensure quality construction.
From the Paper "In the modern Western world, quality construction is generally taken for granted. Although it was once expected that each member of a town or village participate in construction. few people today are involved in the building of their own homes. Only a small percentage of the population is involved in the construction of the roads on which the majority of the population drives. It is a vast minority of people that have played any part in the creation of the structures in which they live, work, or shop. To the average person, there is little connection made mentally between the solid floors supporting his or her weight many stories above the ground, or the protective roof keeping out the elements overhead, and the actual labor which was put into these things. If the construction process is flawless, then no one will have to think about it once completed. However, if the quality of the project is not high, people will not only think about the construction, but also be rightfully upset."
Abstract In support of TQM, this essay goes in depth to define TQM, describe various functions of TQM and applies it to today's business world. As technology and production vastly improved over the past decade, the need for quality process improvements became apparent more than ever. The paper shows practical applications of TQM today (with examples) and also briefly describes various quality awards.
From the Paper "The major new element in world market competition is quality and maintaining that level of quality. During the 1970's and 1980's, the Japanese and their U.S. companies demonstrated that high quality is achievable at lower costs and greater customer satisfaction. It was the result of using the management principles of total quality management (TQM), continuous process improvements (CPI) and quality improvement tools. More and more U.S. companies have demonstrated that such achievements are possible using TQM as a new way to manage. Such companies also found that they were recognized with everyone pulling in the same direction, with the creation of quality awards such as Malcolm Baldridge and ISO 9000."
Abstract This paper examines how Major General Hobart was given an assigned task during World War II to develop some of the most unusual pieces of military equipment ever seen. It looks at how Hobart and his division designed tanks that were named "Hobart's Funnies" and how among these specialized tanks were the Bobbin, Crab, Fascine, Small Box Girder, Crocodile, AVRE Recovery vehicle, ARC Mark II, Bulldozer and the DD Tank. It shows how these tanks were important because they helped the Allies overcome German obstacles and made a huge difference in the D-Day operations.
From the Paper "Percy Hobart graduated from the Royal Military Academy in 1904 where he was commissioned into the Royal Engineers. He served in India, France, and Iraq during World War I, where he gained the respect of his comrades and became know as a "Brilliant but independent-minded officer". Hobart believed that tanks were the future of ground warfare and joined the brand-new Royal Tank Corps in 1923. He then became a Colonel in 1928 and in 1934 he formed and gained command of the 1st Tank Brigade, where he began to develop new tank tactics in the content of mobile warfare. "
Abstract This essay provides a short biography of Orville and Wilbur Wright and their invention of the airplane early last century. The paper explains that the airplane was a technical mystery for many years, but relying on each other's strengths, they worked very well as a team to solve the problems. It concludes that even though the brothers were not formally educated, they succeeded in inventing one of the most revolutionary technologies of all time.
From the Paper "The Wrights' growing local reputation as skillful cyclists and mechanics led to many requests from friends to fix their bicycles. In 1893 they capitalized on the situation and opened a small rental and repair shop. Their bicycle business provided them with an adequate and enjoyable living, an upstanding reputation in the local business community, and an outlet for their mechanical interests. Knowledge and experience with bicycles also proved valuable to the Wrights' development of a successful airplane."
Abstract This paper explains that smart materials are devices, which can sense various stimuli from outer environment such as thermal, electrical and magnetic changes and can respond accordingly; basically, they are materials that sense and respond like living things. The author points out that two families of passive seismic control devices exploiting the peculiar properties of SMA kernel components have been implemented and tested within the MANSIDE project (Memory Alloys for New Seismic Isolation and Energy Dissipation Devices: Special braces for framed structures and isolation devices for buildings and bridges. The paper states that, with these smart materials, engineers are able to build the best and safest structures where possible catastrophic changes in the environment are sensed and precautions are taken directly. 10 figures.
Table of Contents
Introduction
What is a Smart Material?
Types of Smart Materials
Classification Based on Input
Electrical Fields
Thermal Fields
Magnetic Fields
Comparison Based on Output
Strain
Changes in Other Properties
Applications
In Civil Engineering
Uses of Shape Memory Alloys
Smart Concrete
In Other Areas
Conclusion
From the Paper "The first experimental demonstration of the piezoelectric properties in relation to crystal structure was published in 1880 by Pierre and Jacques Curie. This effect was considered quite important and was referred to as "piezoelectricity" in order to distinguish it from other areas of scientific phenomenological experience such as "pyroelectricity" (electricity generated from crystals by heating). As an aside, piezoelectrics also tend to be pyroelectrics. The Curie brothers did not predict that crystals exhibiting the direct piezoelectric effect (electricity from applied stress) would also exhibit the converse piezoelectric effect (stress in response to applied electric field). This property was mathematically deduced and hypothesized by Lippmann in 1881. The Curies then confirmed the existence of the converse effect, and continued on to obtain quantitative proof of the complete reversibility of mechanical deformations in piezoelectric crystals."
Abstract This paper overviews light rail technology and, specifically, Houston's light rail system. It also investigates whether or not the light rail has been a partial solution to Houston's crowded streets. Also, the costs of the system are discussed as well as future expansion plans.
Table of Contents
Light Rail Technology Overview
The Houston Light Rail System
Has the Houston Light Rail Been a Partial Solution
to Traffic Congestion in Houston
Costs of Building and Operating the Houston Light Rail
System and Future Expansion Plans
Opportunity Costs
MetroRail Accidents
From the Paper "Light rail systems typically are operated by electricity that is delivered through overhead lines. Occasionally, they use a third rail for its electrical power, whether they are standard or special third rail systems that only transmit power when the train is on that segment of the track. A few use diesel powered trains; however, this is often used as an interim measure until funding is available for the installation of electric power."
Abstract This paper uses the example of an actual working organization, The Standard Register Company, to investigate the wide variety of problems that fall under the area of supply engineering management.
From the Paper "Warehousing Logistics Transportation is an Engineering Task made up of many and varied components depending upon the complexities of the business. For example, a company dealing with a low number of products as output, with a corresponding low number of raw materials needed for the production of the output has easily solvable Warehousing Logistical Transportation problems. On the other hand a company dealing in a plethora of products as output and even more complex raw materials required in the manufacturing process presents a tremendous Engineering challenge."
Abstract This paper outlines the history of the Titanic steam liner, providing many details about the entire process of the ship's construction. The paper discusses the plans for building the ship, the construction process, and describes the safety features that were built into the ship. Included with the paper is a questionnaire concerning various aspects of the Titanic's construction and history.
Outline
Introduction
History of the Plan to Build the Titanic
Discuss the companies and individuals involved in the
building of the ship.
Describe locations, workers and the overall attitude in
building the ship, inclusive of gantry detail, famous quotes
and competing companies and ships.
Construction of the Ship
When, where and how the ship was constructed
Description of the ship itself, inclusive of tonnage, size, engines,
propellers, unique designs, and materials involved.
Discussion of the ship's dressings, considering such things as
restaurants, lounges, promenade deck, central staircase,
elevators, 1st, 2nd, 3rd class conditions.
Safety Features of the Titanic
Consideration of design features regarding safety of the vessel,
including watertight compartments and hull design.
Other safety features aboard ship, such as lifeboats, floatation
devices, wireless communications systems.
Conclusion
From the Paper "Determined to eclipse the appointments of earlier Atlantic steam liners, White Star Lines set out in 1908 to build 3 ships, all of the same design, that would provide the company with a weekly east- and west- bound carrier service. These ships, the Olympic, the Titanic, and the Gigantic (later to become the Brittanic), were to have a passenger and cargo capacity which doubled that of the Cunard Line, White Star's main competitor in North Atlantic crossings. They were to be longer than Cunard's Lusitania and Mauretania by over 120 feet each, and heavier than those vessels by at least 12,000 tons."
Abstract This paper explains the variables that must be considered in the decision to develop nuclear power capability such as (1) the actual location of a nuclear power plant, (2) the question of security and (3) the compatibility of entering into a nuclear program within the context of the country's long-range energy plans, international policies and aspirations and their level of scientific and technical education. The author points out that the critical gap in plans to expand British civil nuclear programs, which is widely recognized both by promoters and opposers of nuclear power, is the problem of managing radioactive wastes. The paper relates that the French policy differs from from the British policy in that it has gone beyond the concept of "nuclear substitution", designed to diversify and stabilize energy-producing capacity, into a policy of "nuclear electrification" under which the growth of electricity consumption has been deliberately encouraged.
From the Paper "The lack of progress in the British industry reflects a number of fundamental differences between the two nations. One is relatively energy-rich while the other is energy-poor, and the insecurity experienced by the French has been much less marked on the other side of the Channel. On the contrary, the British have enjoyed a flexibility in energy options that is enviable. But beyond commercial questions, and beyond questions of energy supply and demand, lie the differences in institutional power and control and differences in political planning processes that expose the actions of the British industry to far more democratic scrutiny. The anti-nuclear lobby, though less volatile than its French equivalent, is stronger and more consistent. Faced with the luxury of choice, the decision-making process slows to the point of meandering and energy planning wallows in incoherence. This has two, sometimes, conflicting, consequences. Precipitate action on a major scale is checked, but the price of these checks may be slackening technical impetus and loss of commercial advantage."
Abstract On 28 January 1986, the world was shocked by the destruction of the Space Shuttle Challenger, and the death of its crew. This paper examines the processes used in deciding to launch the ill-fated mission. It focuses on the flawed culture within the National Aeronautics and Space Administration (NASA) and its associated mismanagement. It analyses how this culture influenced NASA's beliefs, its decision-making process and its performance.
Outline
Background
Engineering
Management Issues
Belief Systems
Conclusion
Bibliography
From the Paper "President Nixon endorsed the Shuttle during the 1972 election year because it would increase employment. In a crime against the English language, he announced that the vehicle would "revolutionise transportation into near space, by routinising it." He also recognised that it was politically unacceptable not to maintain a manned presence in space. However, the Office of Management and Budget continued to monitor the programme's costs. NASA was forced to make savings in the short term, at the expense of higher operational costs and greater risks. Solid-rocket boosters were chosen because they were less expensive to develop and could be more quickly refurbished than boosters using liquid propellants."
Abstract This paper examines how the 'M6 Toll' was born as the Birmingham Northern Relief Road and how its transformation was far deeper than its name suggests, as the project represented a radical model for infrastructure projects in the United Kingdom. It looks at how the concession and funding arrangements resulted in a focus on the development of long-term revenue, rather than building cheaply to meet a short-term budget.
Outline
Introduction
MEL and CAMBBA
Public Relations
Belief Systems
Conclusions
Bibliography
From the Paper "MEL was very successful in promoting the BNRR. Its success was partly due to the involvement of private industry, which was able to use innovative techniques to convey its message. There is a great contrast between the project's newsletters and the staid announcements from the Highway Agency, eg when the road was officially designated the 'M6 Toll'. (The name itself betrays the Agency's lack of imagination. What will happen if tolls are ever charged on the current M6? Does nobody recall the turnpikes of the 18th and 19th Century?) Shenstone is one of the closest villages to the route. The Chairman of the Parish Council admitted "It has not been as bad as everybody thought it would be. Those involved in the construction have been very pro-active and the disruption has not been as bad." (Edge 2003)"
Tags: birmingham, bnrr, cambba, motorway, nlp, staffordshire, transport, value
Abstract This paper discusses the history of traffic and the effect of population growth, technology and trade on the state of traffic in the city. Providing statistics it expands, through examples, on the results of heavy traffic and the reasons for the increase. In conclusion, the author offers examples, strategy and reasoning of how cities have managed to overcome major urban traffic problems.
From the Paper "Indeed, there are classic examples worldwide of cities where population growth and its resulting issues have created traffic problems. Of course, New York City is the epitome of legendary traffic problems that have stemmed from population growth. Specifically, as the city's economy has boomed, traffic congestion has worsened, and the result is increased costs and lowered productivity for companies large and small. In fact, last year, a nonprofit consulting firm, Community Consulting Services, Inc. estimated that traffic congestion would cost New York City businesses $8.3 billion, which is an increase of 25% from 1997 (Lentz 1)."
Tags: transportation, city, mobility, planning, strategy
Abstract This paper explains that the invention of the steam engine, which led to the steamboat and the steam locomotive, began mankind's technological leap forward that continues today. The author points out that, secondary to the invention of the steamboat was the locomotive steam engine, which allowed direct transportation from cities on the Atlantic Ocean to cities on the Pacific Ocean without having to traverse the Cape of Good Hope in the extreme southern hemisphere, making it more affordable to ship goods and farm products. The paper relates that public transportation was not available in the United States until after the Civil War; its availability was responsible for the creation of the suburbs.
Table of Contents
Transportation Prior to the 19th Century
The Steamboat
The Steam Wagon
Conclusion
From the Paper "How did the invention of the steam engine change the face of American history? The United States was rich in rivers, most especially the Mississippi Rivers that connected the Great Lakes (eventually connected by the Hudson River through the Erie Canal from Chicago to Louisiana. The Louisiana Purchase would have been a poor bargain if it did not include access through the Mississippi and Missouri rivers. Until the steamboat became practical, large river barges were poled by hand and smaller boats such were paddled. Both methods were highly labor intensive and slow. Sailboats were not practical outside of the oceans and Great Lakes. Even then, the vessels were dependent on prevailing winds (or lack thereof)."
Tags: steamboat, steam-locomotive, direct, public, power
