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Radio-Electronics

1. The science of electronics belongs to the twentieth century, although many of its mathematical aspects were worked out in the latter part of the nineteenth century.

2. The field of electronics is usually thought of as electricity that is used in radio, television and other equipment where electron tubes and transistors are needed.

3. That the radio is the fastest and most reliable way to detect artificial sattelites is well known to everybody.

4. In picture transmission the amplitude of the waves radiated at any one time is made proportional to the light intensity of the part of the picture that is being transmitted at that instant.

5. One way to do this is to vary the amplitude of the radiated wave in accordance with the intelligence which is to be transmitted.

6. The process by which the signal being transmitted is reproduced from the radio-frequency currents present at the receiver is called detection, or sometimes demodulation.

7. The delay may amount to the time of several cycles although, of course, the output frequency is the same as the input frequency.

8. By properly controlling and mixing the signals in these many elements, the sonal system can steer the emitted pulse to the desired location and determine the direction that echoes are received from.

9. The manner in which the conductivity is altered is all important in determining the characteristics of devices fabricated in the silicon, but before we consider this we will compare the resistivity of intrinsic silicon with that of a good electrical conductor, copper, and that of a good electrical insulator, ceramic.

10. DSP can compress the pulse after it is received, providing better distance determination without reducing the operating range.

11. The direction to the object is found more simply: you know where you pointed the directional antenna when the echo was received.

12. While these applications have a common thread, each has its own specific problems and needs.

13. A general trend in this field is that techniques with high spatial resolution and high sensitivity gain more and more importance.

14. If an electric field higher than about 3kV/cm is applied to the stable GaAs diode, the existence of growing space-charge waves is possible.

15. Near the cathode of the stable diode, microwaves excite the space-charge waves, which grow as they travel down the electron stream.

16. As the amplification is due to space-charge waves traveling along the electron stream, the microwaves are not amplified if microwaves are injected into the anode side.

17. If the cross-section of the GaAs TWA sample is given, the saturation power of the first type is higher than that of the second type.

18. Since a low carrier-density bulk GaAs was compensated for by impurities forming deep levels, the temperature coefficient of resistivity was negative.

19. In order to realize a uniform electric field profile in the active region, we designed a tapered structure in which the cross-sectional area of the active region gradually increases from the cathode to the anode.



20. When bias voltages were also applied to the anode SBC, the electric field distribution became rather uniform in the active region.

 

Computer Engineering

1. As soon as more than one person is needed for an activity, each participants efforts will be influenced by their dependencies on what other team members are doing.

2. While experts agree about the size of nanotechnology that is smaller than a nanometer (thats one billionth of a meter) they disagree about what should be called nanotechnology and what should not.

3. It should be noted there is controversy and criticism regarding fuzzy logic.

4. Part of the Boost Graph Library is an interface for how the structure of graph can be accessed using a generic interface that hides the details of the graph data structure implementation.

5. Since we have general ideas about the structure and effect of each rule, it is straight forward to effectively initialize each rule.

6. Although the decomposed system is easier to analyze than a nondecomposed one, the overall system may be too large and not as compact as for neural networks.

7. The only disadvantage to the memory managers method is that because this read-ahead is done in the context of resolving a page fault it must be performed synchronously, while the thread waiting on the data being pages back into memory is waiting.

8. Asyoull discover in this chapter, the method Windows 2000 uses to access the cache depends on the type of data being cached.

9. If the rate at whichdirty pages are being produced is greater than the amount the lazy writer had determined it should write, the lazy writer writes an additional number of dirty pages that it calculates are necessary to match that rate.

10. In other words, the cache manager must find out whether a view of the file at the desired address is mapped into the system cache.

11. It is not clear whether such switching should be prevented orwhetherit provides certain advantage for homeostasis of connections.

12. Weve included this example just so you dont start thinking that all domain names have only four labels.

13. Because of the high degree of non-linearity a traditional PID controller is not really a viable option as the controller would not be valid in all regions of the process.

14. The work leading to this course was motivated by wondering why, in software engineering, there are some people who are one or two orders of magnitude more useful than most people.

15. When a new object is created, there must be no doubt about who is permitted what type of access to it.

16. However, before you can start the debugger, you must ensure that the application you are about to debug has been compiled with debugging information.

17. To avoid the MCU entering the Sleep Mode unless it is the programmers purpose, it is recommended to set the Sleep Enable (SE) bit just before the execution of the SLEEP instruction.

18. What is labeled design in fig.3.1 is not yet the product itself.

19. If two features contact each other, the one whose feature reference is higher is given the precedence.

20. For algorithms to do their work, they must examine every object in the range they are passed, and they do this in the way you would expect: the loop from the beginning of the range to the end.

21. Although the fixed network applications will drive the use of data over cellular network, they will also raise users expectations of the performance of cellular services.

22. Its only natural to seek a computer system that offers the freedom and flexibility to match your own creativity and needs.

23. AsI mentioned earlier, any initialization code that the DLL needs to execute can be done in the DLLs main code block.

24. Static loading means that your DLL is automatically loaded when the application that calls the DLL is executed.

25. Once you have finished with your ACM session it is time to free the resources we have used.

26. The codes you specified on your machine may not be available on a client machine.

27. Once you receive a buffer of data from the wave input device it is already compressed and ready for transmitting.

28. Before using the right-to-left evaluation of the expression first look to see ifany of the operators have different precedence.

29. The disadvantage of this approach is that if a DLL that the program references is missing, the program will refuse to load.

30. Graphs which are randomly generated, by making each pair of vertices an edge with fixed probability p, are almost always easy to solve by a simply backtrack routine with a very valve heuristic.

31. The graph authomorphism decision problem which asks ifthere exists a nontrivial authomorphism, is an interesting exception.

32. When desk top computers first appeared, it was thought by some thatTCP was too big and complex to run on a personal computer.

33. If larger clusters are formed, there would be fewer of them in number.

34. Ifthe number of rows into which the cells are placed is changed, the resulting clusters and also the impact on the simulated annealing algorithm will vary.

35. The broad criterion for clustering is thatcells within a cluster must have strong connections among themselves and weak connection to other cells.

36. For the simulated annealing applications, our experience indicates that to get good quality results, it is important to localize nets to within clusters.

37. Terminal count is the next important attribute, since it not only reflects strong connectivity within a cluster, but also impacts the computation time.

38. When clustering is used with simulated annealing the CPU time for clustering represents only a small fraction of the total CPU time for placement.

39. The distinguishing aspect of the various schemes is the order in whichthe clusters are selected for enlargement.

40. As new clusters are formed, they are immediately considered in evaluating whetherother clusters should be combined.

41. The algorithm terminates when no more clusters can be combined without violating the constraint on the size.

42. We use the estimated wire length to compare the quality of the results, since this is the cost function being minimized during simulated annealing.

43. Since we fixed the number of moves per cell per temperature at 100, the cost computation has somewhat of a linear dependency on the total number of terminals.

44. In addition to the improvement in CPU time, we also find that the quality of the results has improved.

45. For large problems, we can either achieve an additional improvement in the solution quality or a much more significant improvement in the CPU time, depending on whetheror not the number of moves per cell is increased to account for the larger search space.

46. In fact the scheme would be equally applicable to finding the strongest of several sinusoids provided one were not interested in any of the weaker ones.

47. To achieve the desired reduction in cross-over levels, which is now the cross-over between a natural and a synthesized cell, it is not essential that the shape of the latter should be the same as that of the former.

48. One disadvantage to the Delphi programming model is that it doesnt use traditional resources as other programming environments do.

49. This saturation time increases asthe solution space gets larger.

50. Since the radio medium can be accessed by anyone, authentication of users to prove that they are who they claim to be, is a very important element of a mobile network.

 

Information Security

1. Even professionals who work in information security do not agree exactly what terms like security, protection, and privacy mean.

2. If you dont know what you are protecting, why you are protecting it, and what you are protecting it from, your task will be rather difficult.

3. Whatyou need is to understand how to establish and apply uniform security policies.

4. For most organizations, unauthorized access is not a major problem unless it involves one of the other threats: disclosure of information or denial of service.

5. A well-thought-out security plan will help you decide what needs to be protected, how much you are willing to invest in protecting it, and who will be responsible for carrying out the steps to protect it.

6. An insidious aspect of DoS (Denial of Service) appears when your system becomes an unwitting tool of the attackers.

7. We are all familiar with cases where web vandals gain access to a web server and change the data on the server in order to embarrass the organization that runs the web site.

8. Denial of service can be a severe problem if it impacts many users or a major mission of your organization.

9. Some browsers (such as Mozilla Firefox and Opera) have an option to have the system clear cookies automatically whenever the user closes the browser.

10. What information an ISP collects, what it does with that information, and whether it informs its consumers, can pose significant privacy issues.

11. This may include recording times whenthe computer is in use, or which web sites are visited.

12. Computer security imposes requirements on computers that are different from most system requirements becausethey often take the form of constraints on what computers are not supposed to do.

13. This makes computer security particularly challenging because we find it hard enough just to make computer programs do everything they are designed to do correctly.

14. Strong authentication techniques can be used to ensure that communication end-points are who they say they are.

15. In 1983, Korean Airlines Flight 007, a Boeing 747 was shot down by Soviet SU-15 jets after a navigation computer malfunction caused the aircraft to steer 185 miles off course into Soviet Union airspace.

16. They inform people on how the business is to be run and how day to day operations are to be conducted.

17. Before ordering a product or service online, the user and the online service provider or merchant negotiate the type of personal data that is to be transferred to the service provider.

18. While this negotiation takes place, the online service provider communicates his requirements about the minimum amount of data he needs to provide the wanted service.

19. A virus is a piece of software designed and written to adversely affect your computer by altering the way it works without your knowledge or permission.

20. A virus that conceals itself until some predetermined date or time and then does nothing more than display some sort of message is considered benign.

21. Additionally, you should evaluate your router logs and examine status information on your routers periodically, to detect networking problems, and eventually change to restrictive or emergency access lists you have previously compiled, for the case thatnetwork critical events occur.

22. Another important service whichincident response and emergency consulting should offer is informal and anonymous consulting.

23. Because of the decentralized, non-authoritative nature of the Internet, information is being distributed over a variety of different channels, including security organizations, but also news groups, and media sites, which often do not provide reliable and complete information, causing unnecessary panic and paranoia on one hand, and insufficient awareness on the other.

24. Sincethe first traffic loggers and port scan detectors had been designed, classical intrusion detection has been relying on monitoring network traffic and system events and identifying unusual actions and objects to determine intrusions.

25. When a new protocol architecture is being described, software developers should at least be given hint about wherepossible caveats and vulnerabilities could be present.

 

Economics

1. Man wills himself by overwork in order to secure property. One's regret is thatsociety should be constructed on such basic, that man has been forced into a position in which he cannot freely develop what is wonderful, and fascinating, and delightful in him (O. Wilde).

2. Instead of being seen as an opportunity to diversity investment and therefore to spread risk, globalization has lately become muddled up with so-called "new paradigm" in America - the seductive doctrine, verging on clap-trap, that says thatinflation is dead, thatold economic laws have been repealed and that America's stock markets can therefore keep on growing indefinitely at their present rate.

3. Developing and marketing the technology jointly is the preferred option whena company controls the technology but lacks the resources to build one or more of the complementary assets needed to gain a competitive advantage - that is, the company cannot find a share-building or a growth strategy.

4. In one survey, 62 percent of shoppers surveyed said they had decided not to buy a product in a store in the past six month because sales clerks were not available to help them.

5. Whether on balance high taxes make people work more or less remains an open question.

6. Many consumers believe they are more pressed for time than ever before.

7. It has been estimated that if present trends for industrial and artistic use of gold continue, in a few years it will be equivalent to almost the whole of projected world supply, without making any allowance for additions to official reserves.

8. While giant corporations determine much of the nations economic behavior, entrepreneurs also have a significant impact on the American economy.

9. Because services are inseparable in that they are not produced until the time they are consumed, it is difficult to make a repurchase evaluation of quality.

10. Whether or not demand is elastic is the key piece of information required in setting the price of football tickets (as an example).

11. The food in a restaurant or the furniture of a hotel room may be outstanding, but if the waiter or the room attendant provides inattentive service, customers will be disappointed with their experience.

12. A couple may have chosen a restaurant becauseit is quiet and romantic, but if a group of loud tourists is seated next to their table, the couple will be disappointed.

13. If in the production of a commodity, one factor of production is increased by stages while the other factors are kept unchanged, the stage will sooner or later be reached where each further addition to the increasing factor will produce a smaller and smaller increase in output.

14. What determines whetherthe price elasticity of demand for a good is high or low?

15. If we assume that all the goods and services, which are produced are in fact sold and that households spend their entire income, then we have arrived at what economists call a neutral equilibrium.

16. Ifthe authorities withdraw funds through taxation and then fail to spend this tax revenue, the circular flow will reduce the level of activity in the economy.

17. Whatever the reason, if people save more they spend less and business suffer falling sales.

18. If an insurance company wishes you a happy birthday, take it as a sign that they view you as a target for a touch of cross marketing. In other words, having sold to you once or twice before, they would like to do it over and over again.

19. We dont know whether the new financial policy of the government will be successful.

20. They tell us whether the economy is working at full capacity using all or nearly all, available resources of labor, machinery and other factors of production or whether these resources are being under-utilized.

21. It has been estimatedthat if present trends for industrial and artistic use of gold continue, in a few years it will be equivalent to almost the whole of projected world supply, without making any allowance for additions to official reserves.

22. As trade becomes more complex and involves a greater number of goods, a monetary commodity usually emerges.

23. As the rates and terms vary, services have been set up allowing users to calculate savings available by switching cards, which can be considerable if there is a large outstanding balance.

24. Because of intense competition in the credit card industry, credit providers often offer incentives such as frequent flyer points, gift certificates, or cash back (typically up to 1 percent based on total purchases) to try to attract customers to their program.

25. Usually, if a customer is late paying the balance, finance charges will be calculated and the grace period does not apply.

26. A credit card's grace period is the time the customer has topay the balance beforeinterest is charged to the balance.

 

Tourism

1. The food in a restaurant or the furniture of a hotel room may be outstanding, but ifthe waiter or the room attendant provides inattentive service, customers will be disappointed with their experience.

2. A couple may have chosen a restaurant because it is quiet and romantic, but ifa group of loud tourists is seated next to their table, the couple will be disappointed. Classically, though, a motel is a hotel which is made convenient for people who, for whatever personal reason, wish to be able to have quick access from the outside world (especially from their parked car) to the hotel room - without passing the scrutiny of a receptionist or fellow guests.

3. There are also hotels which became much more popular through films like the Grand Hotel Europe in Saint Petersburg, Russia when James Bond stayed there in the blockbuster Golden Eye. Cannes hotels such as the Carlton or the Martinez become the center of the world during Cannes Film Festival (France).

4. The United Nations classified three forms of tourism in 1994 in its Recommendations on Tourism Statistics: Domestic tourism, which involves residents of the given country traveling only within this country; Inbound tourism, involving non-residents traveling in the given country; and Outbound tourism, involving residents traveling in another country.

5. Pilgrimages created a variety of tourist aspects that still exist - bringing back souvenirs, obtaining credit with foreign banks (in medieval times utilizing international networks established by Jews and Lombards), and making use of space available on existing forms of transport (such as the use of medieval English wine ships bound for Vigo by pilgrims to Santiago De Compostela).

6. The Fun Ski & Snow Festival, which has been organized annually by Korea tourism organization since 1998 and participated by about 10,000 tourists from Asia, is one of the most successful winter tourism products in Asia.

7. Because of the many associations with the term, it is difficult to characterize a term like behavior without specifying a context of discourse in which it is to take on meaning.

8. Travel consolidators or wholesalers are high volume sales companies thatare sometimes specialized in a niche.

9. Generally speaking, small or specialist tour companies do not sell their product through travel agents, since they could not afford to pay the rates of commission that would be expected.

10. In 2000, the Tourism and Leisure Research Group of the School of Management at the University of Surrey asked potential customers whether virtual tourism provided a viable alternative to traditional forms of travel (Baur 2000).

11. Tourism-related environmental damage can be extremely serious, not only because of the environmental and human health risks it imposes, but also because of the economic importance to many countries of the environment-dependent tourism trade.

12. The most cost-effective approaches generally focus pollution prevention, sinceit is less costly to ensure environmentally safe tourism through planning than to repair damage caused by uncontrolled tourism after it occurs.

13. Although dental tourism is technically part of the larger medical tourism industry, many would argue that it deserves a category of its own due to its specialized nature.

14. This is why any projections of growth in tourism may serve as an indication of the relative influence that each country will exercise in the future.

 

Psychology

1. Ifyou are afraid of poisonous spiders, it is logical. Ifyou are afraid of all spiders, even harmless ones, this is a phobia because it is illogical.

2. If you dream about something that is worrying you, you may wake up exhausted, sweating, and with a rapid heartbeat.

3. Since our world can sometimes be stressful, it is important to find ways to handle stress.

4. If you often feel angry and overwhelmed, like the stress in your life is spinning out of control, then you may be hurting your heart.

5. Ifyou put your energy into being your best self rather than wasting your energy on an image, you will reap rewards.

6. It was also found that the event had to be mentally upsetting to impair memory which indicated that such an event somehow interrupted full storage of information in memory.

7. One of the common criticisms of experimental work on the misinformation effect is that the findings are not general sable to real-world witnessing situations. However, studies, which try to account of this criticism, encounter problems of their own.

8. Over a hundred years ago it was shown that memory deteriorates at an exponential rate i.e. we forget more gradual( known as the forgetting curve).

9. The belief that memories are permanently recorded as though they were a video recording has been challenged by many psychologists.

10. Whether knowingly or otherwise, the effects of seeing red have been cleverly exploited by fast food chains.

11. At the centre of much debate have been the questions how dance can express emotions in any detailed way and whether it can be thought of as a kind of language.

12. When the force keeps a person within the bounds of justice, they impose nothing but a mere negation.

13. If you are a student who always revises on black coffee, perhaps it would be sensible to prime yourself with a cup before going into the exam.

14. If you are thinking about a problem or about something exciting that is going to happen the next day, get up and write about it.

15. Mind, that it is not wrong ifyou do not like a certain color, it simply provides information for you to explore.

16. Although we cannot observe the mind directly, everything we do, think, feel and say is determined by the functioning of the mind.

17. Since the German psychologist Wilhelm Wundt (1832-1920) opened the first experimental psychology lab in Leipzig in 1879, we have learned an enormous amount about the relationship between brain, mind and behaviour.

18. Positive psychology is a recent branch of scientific psychology that "studies the strengths and virtues that enable individuals and communities to thrive.

19. When people experience stress, they show increased heart rate, higher blood sugar, immune suppression, and other adaptations optimized for immediate action.

20. Physiological psychology is a subdivision of biological psychology thatstudies the neural mechanisms of perception and behavior through direct manipulation of the brains of nonhuman animal subjects in controlled experiments.

21. The storage in sensory memory and short-term memory generally have a strictly limited capacity and duration, which means that information is available for a certain period of time, but is not retained indefinitely.

 

Law

1. Questions related to an offence may not normally be put to a person as soon ashe or she has been charged with that offence.

2. That a person may be visited by a legal adviser in custody is well known to all citizens.

3. However, official statistics covers only crime recorded by the police and may thus be affected by changes in the proportion of crime which are undiscovered or unreported.

4. That the citizens must know the law and live their lives accordingly goes without saying.

5. Private law involves the various relationships that people have with one another and the rules that determine their legal rights and duties among themselves.

6. Unless the Governments strategy had been aimed at preventing crime where possible, more crimes would have bee committed in the country.

7. The police may delay a person for up to 36 hours in the interests of the investigation providedcertain criteria are met.

8. If a person breaks the law, he will be brought first before a Magistrates Court.

9. Unless the accused person was proved guilty beyond a reasonable doubt he would not be convicted.

10. If the court deals with minor criminal cases such as misdemeanors, it will impose penalties involving fines or jail terms of no more than one year of imprisonment.

11. Whether to conduct pre-trial hearings in serious criminal cases, including those at which bail is set, is decided by the state trial courts.

12. Whether the case may be filed in federal court is determined by a specific Federal statute.

13. Those who were skilled in the law that they could decide a novel or doubtful case were called juris prudentes , whether or not they were judges, and the body of law built up by their interpretation was called juris prudential.

14. If the defendant denies committing the acts charged against him, the court will have to choose between his version of the fact and the prosecutions.

15. The efforts of the police would not result in preventing crime ifthey did not coordinate good relations with the community.

16. Whether the High Court may impose a sentence of imprisonment for any term up to life depends on indictment.

17. There is a rapid growth in the number of locally run victim support schemes which offer practical help to the victims of crime on voluntary basis.

18. As soon as there is sufficient evidence to charge a person, the police must decide on an appropriate method of dealing with him or her.

19. An accused person should know whether he is entitled to apply for release on bail.

20. In many jurisdictions, jury trials in criminal cases are automatic unless they are waived by the defendant.

21. The rules all of us live by are provided by law which in many ways is cornerstone of culture.

22. Private law involves the various relationships thatpeople have with one another and the rules that determine their legal rights and duties among themselves.

23. Trust law applies to assets held for investment and financial security, such as pension funds.

24. The study of law raises important questions about equality, fairness and justice, which are not always simple.

25. Criminal law is the body of law that defines criminal offences and the penalties for convicted offenders.

26. The main alternative to the common law system is the civil law system, which is used in Continental Europe, and most of the rest of the world.

27. Scotland is often said to use the civil law system but in fact it has a unique system that combines elements of an uncodified civil law dating back to the Corpus Juris Civilis with an element of common law long predating the Treaty of Union with England in 1707.

28. The property agreement must satisfy all formalities required in the Country whereenforcement is sought.

 

Aircraft Building

1. The number of stages depends on whether the engine has one shaft or two and also on the relation between the power required from the gas flow, the rotational speed at which it must be produced and the diameter of turbine permitted.

2. In fact, the jet propulsion engine, whether rocket, athodyd, or turbo-jet, is an apparatus designed to accelerate a large stream of air and to expel it at a high velocity.

3. The question is not only whether such specific noise reductions are technologically feasible, but at what price to the air transport and travel industry they will be achieved.

4. If careful inspection reveals nothing, a check of all voltages within the unit vertical take-off and landing) will often show up the faulty circuit.

5. If the flow of exhaust gases is impeded by too small an exit, temperatures and pressures will be built up inside the engine, while too large an exit will make them fall, and create a loss of thrust.

6. Ifthe amount of thrust required for a particular aircraft exceeds the capacity of a single-engine aircraft, designers employ multi-engine configurations.

7. Because of the different ageing and reliability characteristics of semiconductors and the ease with which semiconductor devices can be inadvertently damaged during routine maintenance checks, a rather different approach towards electronic maintenance is developing.

8. Because of the expense that can result from a minor fault putting elaborate equipment out of action, considerable research into reliability, e.g. component reliability testing programmers, has been undertaken in recent years.

9. The types of jet engines differ in the way inwhich the engine supplies and converts the energy into power for flight.

10. At an altitude of 20,000 meters the pressure in the passenger cabins of the Tu144 is maintained at the level it would be ifthe plane were flying at 2,400 meters.

11. Its characteristic feature is the ability to explore the configuration space via configurations thatactually increase the cost function being minimized.

12. A parameter called temperature is defined, which is of the same dimension as the cost function.

13. A number of other experiments were intended to look at how solar panels and other equipment and materials could be operated even in the hostile and pervasively dusty environment of Mars.

14. Ifones aim is to increase the accuracy of spectrum analysis in general, then use the interpolation scheme is not recommended.

15. However it is of interest to see whetheran acceptable approximation is achievable in this way.

16. An aircraft is a vehicle which is able to fly through the air (or through any other atmosphere). All the human activity which surrounds aircraft is called aviation.

17. Rocket-powered missiles which obtain aerodynamic lift at very high speed due to airflow over their bodies, are a marginal case.

18. Many US airports still lease part or all of their facilities to outside firms, who operate specific functions such as retail management and parking. In the US, all commercial airport runways are certified by the FAA, but maintained by the local airport under the regulatory authority of the FAA.

19. The next big boost for the airlines would come in the 1970s, when the Boeing 747, McDonnell Douglas DC-10, and Lockheed L-1011 inaugurated widebody ("jumbo jet") service, which is still the standard in international travel.

20. Tithe government often intervenes to halt airline labor actions in order to protect the free flow of people, communications, and goods between different regions without compromising safety.

21. Full-service airlines have a high level of fixed and operating costs in order to establish and maintain air services: labor, fuel, airplanes, engines, spares and parts.

22. Supersonic flight brings with it substantial technical challenges, asthe aerodynamics of supersonic flight are dramatically different from those of subsonic flight (i.e., flight at speeds slower than that of sound).

23. The origin of the actual screw propeller starts, in the West, with Archimedes, who used a screw to lift water for irrigation and bailing boats, so famously that it became known as the Archimedes screw.

24. The first 'real-world' use of a propeller was by David Bushnell, whoused hand-powered screw propellers to motivate his submarine "The American Turtle" in 1776.

25. When used on powered gliders and single-engine turbine powered aircraft they increase the gliding distance.

26. Contra-rotating propellers use a second propeller rotating in the opposite direction immediately 'downstream' of the main propeller so as to recover energy lost in the swirling motion of the air in the propeller slipstream.

27. As air enters the duct, its speed is reduced and pressure and temperature increase.

28. The lifting body is an aircraft configuration where the body itself produces lift.

29. The internal combustion engine is an engine in which the combustion of fuel and an oxidizer (typically air) occurs in a confined space called a combustion chamber.

30. If the momentum of the exhaust stream exceeds the momentum of the intake stream, the impulse is positive, thus, there is a net forward thrust upon the airframe.

31. When a hydrocarbon burns in oxygen, the reaction will only yield carbon dioxide and water.

32. . Incomplete combustion occurs when there isn't enough oxygen to allow the fuel (usually a hydrocarbon) to react completely with the oxygen to produce carbon dioxide and water, also when the combustion is quenched by a heat sink such as a solid surface or flame trap.

 



Date: 2015-12-11; view: 242


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