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GPSA The Global Positioning System is a space-based triangulation system using satellites and computers to measure positions anywhere on earth. It is first and foremost a defense system developed by the United States Department of Defense, and is referred to as the "Navigation Satellite Timing and Ranging Global Positioning System" or NAVSTAR GPS. The uniqueness of this navigational system is that it avoids the limitations of other land-based systems such as limited geographic coverage, lack of continuous 24-hour coverage, and the limited accuracies of other related navigational instruments. The high accuracies obtainable with the Global Positioning System also make it a precision survey instrument. GPS Components: the Space Segment, the Control Segment, and the User Segment.B The Space Segment of the system consists of the GPS satellites. These space vehicles (SVs) send radio signals from space. The GPS Operational Constellation consists of 24 satellites that orbit the earth in 12 hours. There are often more than 24 operational satellites as new ones are launched to replace older satellites. The satellite orbits repeat almost the same ground track (as the earth turns beneath them) once each day. The orbit altitude is such that the satellites repeat the same track and area over any point approximately each 24 hours (4 minutes earlier each day). There are six orbital planes (with four SVs in each), equally spaced (60 degrees apart), and inclined at about fifty-five degrees with respect to theequatorial(赤道的) plane. This constellation provides the user with between five and eight SVs visible from any point on the earth.C The Control Segment consists of a system of tracking stations located around the world. The Master Control facility is located at Schriever Air Force Base (formerly Falcon AFB) in Colorado. These monitor stations measure signals from the SVs which are incorporated into orbital models for each satellites. The models compute precise orbital data and SV clock corrections for each satellite. The Master Control station uploads orbital data and clock data to the SVs. The SVs then send subsets of the orbitalephemeris(星历表) data to GPS receivers over radio signals.D The GPS User Segment consists of the GPS receivers and the user community. GPS receivers change SV signals into position, speed, and time estimates. Four satellites are required to compute the four dimensions of X, Y, Z (position) and Time. GPS receivers are used for navigation, positioning, time distribution, and other research. Navigation in three dimensions is the primary function of GPS. Navigation receivers are made for aircraft, ships, ground vehicles, and for hand carrying by individuals. Precise positioning is possible using GPS receivers at reference locations providing corrections and relative positioning data for remote receivers. Surveying, geodetic control, and plate tectonic studies are examples.E Time and frequency distribution, based on the precise clocks on board the SVs and controlled by the monitor stations, is another use for GPS. Astronomical observatories, telecommunications facilities, and laboratory standards can be set to precise time signals or controlled to accurate frequencies by special purpose GPS receivers. Research projects have used GPS signals to measure atmospheric parameters.F At present the system consists of 24 satellites at an altitude of about 20,000 km having an orbital inclination of 55 degrees. The orbits are almost circular and it takes 12 hours for a satellite to complete a pass around the Earth. GPS signals are broadcast from a cluster of 24 or more earth orbiting satellites. Because the GPS signals are derived from the atomic frequency standards on board each satellite, they are widely used as a reference for time synchronization and frequency adjustment. The real time positioning accuracy of a single receiver is normally up to 100 meters horizontally and 150 meters vertically. However, various methods have been developed which enable much higher accuracy (centimeter level).G There are a variety of different types of GPS receivers on the market for commercial and public use. Prices range from $500 to $30,000, reflecting the accuracy and capabilities of the instruments. For the general outdoorsman, a good GPS receiver should have 8 satellite tracking capability and be capable of receiving the GPS satellite signals through forest covering in northern Ontario shield area; for the professional user, a minimum 8 satellite tracking capability, high memory capacity, differential GPS capability, and resistance to signal weakening under forest covering is essential; for the professional surveyor requiring high level precision and accuracy capability, they should assess the project or application for which the technology is to be used with the help of an unbiased consultant, in order to determine the most cost effective and appropriate instrument.H Small hand held navigational units at relatively low cost allow boaters and hikers to know their position within a few hundred meters. This accuracy is sufficient for recreational use. A hand held or similar mapping unit at mid-range price that is linked to a fixed broadcast base station. These units allow utility companies, municipalities and others to locate various items (telephone poles, waterlines, valves) with a positional tolerance of several meters. This is suitable for some Geographical Information Systems (GIS) mapping purposes.I GPS technology offers numerous benefits to law enforcement agencies of all types. For some agencies, the navigational capabilities offered by GPS enhance efficiency and safety. These navigational applications can be used to support a variety of policing and criminal justice functions. Other agencies use GPS positioning technologies to carry out special operations or to provide enhanced personnel safety. For example, using computerized maps of their rights given by law, cooperated with GPS, aviation personnel can determine location, speed and time.J The positioning capabilities offered by GPS may also contribute to the success of specialized law enforcement operations such as in controlling vehicles. One such program operated in Minneapolis led to a 60% reduction in auto theft after only one month. The automatic vehicle location systems can not only provide efficiency of response and help ensure officer safety, but also provide officer with accurate information concerning the best response route to an incident. What"s more, they can provide officers information that allows the closest patrol officers to be dispatched to a particular incident.K Advanced Transportation Management Systems (ATMS) are heavily dependant upon GPS technology to provide data about the road system. GPS allows for law enforcement personnel to clear roadway blockages to ensure the safety of motorist. Most people associate law enforcement with the prevention, reduction, and prosecution of criminal activity. In fact, a large portion of local law enforcement resources are involved in facilitating the movement of people and vehicles in a safe manner. In conclusion, large-volume commercial applications such as cellular phones, personal communication systems, and in-vehicle navigation systems will fuel continued development of these technologies. What was ultimately the domain of the Department of Defense is rapidly becoming available for business, private, and general government use. Policing and public safety in general, will benefit from these market forces. It is clear that there are a number of GPS applications for policing. For recreational use, the accuracy of a hand held GPS unit at relatively low price is good enough.
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Sex prejudices are based on and justified by theideology(意识形态) that biology isdestiny(命运). According to the ideology, basic biological and psychological differences exist between the sexes. These differences require each sex to play a separate role in social life. Women are the weaker sex—both physically and emotionally. Thus, they are naturally suited much more so than men, to the performance of domestic duties. A woman"s place, under normal circumstances, is within the protective environment of the home. Nature has determined that women play care-taker roles, such as wife and mother and homemaker. On the other hand men are best suited to go out into the competitive world of work and politics, where serious responsibilities must be taken on. Men are to be the providers; women and children are "dependents".The idea also holds that women who wish to work outside the household should naturally fill these jobs that are in line with the special capabilities of their sex. It is thus appropriate for women, not men, to be employed as nurses, social workers, elementary school teachers, household helpers, and clerks and secretaries. These positions are simply an extension of women"s domestic role. Informal distinctions between "women"s work" and "men"s work" in the labor force, according to the ideology, are simply a functional reflection of the basic differences between the sexes.Finally, the ideology suggests that nature has worked her will in another significant way. For the human species to survive over time, its members must regularly reproduce. Thus, women must, whether at home or in the labor force, make the most of their physical appearance. So goes the ideology. It is, of course, not true that basic biological and psychological differences between the sexes require each to play sex-defined roles in social life. There is much evidence that sex roles vary from society to society, and those role differences that do exist are largely learned.But to the degree people actually believe that biology is destiny and that nature intended for men and women to make different contributions to society, sex-defined roles will be seen as totally acceptable. The author most probably believes role differences exist because ______.
Six years ago, a Miami woman walking through the hall of an office building casually noticed two men standing together. Several minutes after her leaving, the men murdered a person working in the building. Police investigators determined that the woman was the only witness who had seen the two suspects, and could possibly describe them. In an interview with police, her memory of the men proved disappointingly unclear.Several days later, psychologist Ronald P. Fisher was brought in to obtain a more complete account from the woman. Fisher"s interview produced abreakthrough(突破)—the woman reported a clear picture of one of the suspects. She then recalled several details about his appearances. This information gave police important leads that enabled them to arrest the suspects and close the case.Police investigators sought the help from Fisher because of his rich knowledge in conducting the so-calledcognitive(认知的) interview, a kind of memory-rebuilding process. In its original form, the cognitive interview focuses on guiding witnesses through four general recalling techniques: thinking about physical surroundings and personal feelings that existed at the time of past events, reporting everything that comes to mind about those events no matter how broken or unconnected, retelling events in a variety of time orders, beginning to end, end to beginning, forward or backward, and adopting different perspectives while recalling events.Usually, an interviewer begins the cognitive approach by encouraging the witness to take an active role in recalling information rather than giving answers only to someone else"s questions. The witness first describes what happened in his or her own words, with no interviewer interruptions. The interviewer then goes further with specific techniques, such as having the witness tell the details of what happened from different perspectives.Experiments with police detectives trained in this demanding interview method find that they get nearly 50% more information from witnesses than before training, while error rates remain about the same. It can be inferred from the passage that in a cognitive interview, the interviewer mainly plays a ______ role.
治理通货膨胀可以采取紧缩总需求的政策，以下属于紧缩性财政政策的有______。
企业操纵市场、人为抬高产品价格所引起的通货膨胀，属于______通货膨胀。
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