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81.
The author predicts the future of the Internet. The Internet was first used for remote terminal login, then file transfer, e-mail, and newsgroups. A long time later, we got Web publishing. Now there's Web commerce. Where next? Well, as broadband is deployed and the Internet heads toward all-optical, there will be a lot more e-mail, a lot more Web commerce, and so on. But what new applications will develop? For one thing, the Internet will subsume the telephone network. Telephone traffic is increasing less than 10 percent per year, while Internet traffic is doubling every four months. If Internet traffic did not surpass telephony by the end of the millennium, it will soon. Voice over Internet Protocol (VoIP) will be a trivia sidelight of the Internet right after that. After telephone, television. Internet protocols and bandwidth will need upgrading before television can be carried well, but it inevitably will move to the Internet. Why? The Internet can make television interactive: give it a million channels. The author does not mean turning your TV into a PC monitor, and he doesn't mean carrying the Internet on television networks (CTMs). He means carrying television on the Internet, in packets, using Internet packets: TVoIP. After that: Internet telepresence. There will be major substitutions of communication for travel. Less commuting. Less tedious business travel to press the flesh. We'll wire up our homes and (mostly) stay there 相似文献
82.
军工/航天和商用电子元器件市场常常被认为是两个不同的市场,但实际上,二者之间的共同之处正在不断增加。由于高可靠性业务的数量显著较少,该领域的采购商似乎把目光放在商业客户的对应型号上,当然前提是满足起码的性能要求。这些采购商开始仿照商用标准产品的客户,越来越多地通过分销商来采购所需的元器件。那些军工和航天领域的巨头不再局限于原有的垂直集成业务模式,开始象那些商业OEM厂商一样,考虑将电路板组装业务通过离岸合同制造的方式外包出去,以降低他们的成本。 相似文献
83.
Accurate measurement of cognitive strategies is important in diverse areas of psychological research. Strategy self-reports are a common measure, but C. Thevenot, M. Fanget, and M. Fayol (2007) proposed a more objective method to distinguish different strategies in the context of mental arithmetic. In their operand recognition paradigm, speed of recognition memory for problem operands after solving a problem indexes strategy (e.g., direct memory retrieval vs. a procedural strategy). Here, in 2 experiments, operand recognition time was the same following simple addition or multiplication, but, consistent with a wide variety of previous research, strategy reports indicated much greater use of procedures (e.g., counting) for addition than multiplication. Operation, problem size (e.g., 2 + 3 vs. 8 + 9), and operand format (digits vs. words) had interactive effects on reported procedure use that were not reflected in recognition performance. Regression analyses suggested that recognition time was influenced at least as much by the relative difficulty of the preceding problem as by the strategy used. The findings indicate that the operand recognition paradigm is not a reliable substitute for strategy reports and highlight the potential impact of difficulty-related carryover effects in sequential cognitive tasks. (PsycINFO Database Record (c) 2011 APA, all rights reserved) 相似文献
84.
目前我国软件产业规模小、人员分散、抗风险能力低下,处于发展的初级阶段,但人才优势与发展册时并存。面对挑战,必须有相应的大举措,如联合、重组、兼并,如多方筹资、加大投入,如强化管理、政策扶植等等,最终做出正确选择。 相似文献
85.
This paper presents a vision-based collision avoidance technique for small and miniature air vehicles (MAVs) using local-level frame mapping and path planning. Using computer vision algorithms, a depth map that represents the range and bearing to obstacles is obtained. Based on the depth map, we estimate the range, azimuth to, and height of obstacles using an extended Kalman filter that takes into account the correlations between obstacles. We then construct maps in the local-level frame using cylindrical coordinates for three dimensional path planning and plan Dubins paths using the rapidly-exploring random tree algorithm. The behavior of our approach is analyzed and the characteristics of the environments where the local path planning technique guarantees collision-free paths and maneuvers the MAV to a specific goal region are described. Numerical results show the proposed technique is successful in solving path planning and multiple obstacle avoidance problems for fixed wing MAVs. 相似文献
86.
A. Arnette C. Zobel D. Bosch J. Pease T. Metcalfe 《Environmental Modelling & Software》2010,25(11):1459-1469
More effective methods of eliciting and summarizing stakeholders' goals can assist in improving watershed management. This paper discusses the process of summarizing the goals that were generated during a workshop of watershed stakeholders in Virginia by using the Vector Analytic Hierarchy Process, and then grouping them into homogeneous subgroups by using two different methods: 1) assigning subgroups based on individuals' stated affiliations from a participant bio-sheet; and 2) assigning subgroups based on the similarity of individuals' actual preferences between the goals. Several different clustering approaches are considered for creating the preference-based subgroups, and the relative advantages and disadvantages of each approach are discussed. The process of combining the subgroups to generate a single overall preference structure for the group as a whole is also considered, and the final results are compared based on both the resulting rankings and the coherence, or variability of opinion, that they reflect. Determining the “best” set of subgroups can be valuable not only in exploring the underlying nature of the population's preferences, but also in supporting additional discussion and analysis of the results. As such, it can ultimately lead to much stronger and better informed decision-making by the stakeholders. 相似文献
87.
Jane Loevinger died unexpectedly on January 4, 2008. She was well-known for her work in psychometrics, her theory of ego development, and her widely used assessment instrument, the Washington University Sentence Completion Test. Among the first to focus on women as a demographic, Loevinger obtained funding from the National Institute of Mental Health. She developed measures of women's attitudes and formed a research group of her own that focused on the problems facing mothers and women in general. Loevinger was a perennial iconoclast and skeptic within her fields of interest. Despite her wry wit, or perhaps because of it, her opinions and contributions came to be greatly valued by her colleagues. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
88.
This study addressed two questions: Do daily fluctuations in mood exhibit a 7-day (circaseptum) cycle, and are there reliable individual differences in how entrained peoples' moods are to such a weekly cycle? Spectral analysis of daily mood over 84 occasions revealed a strong weekly rhythm in the temporal organization of mood in a sample of 74 undergraduates. A sine wave with a period of 7 days accounted for 40% of the variance in the daily mood data. Individual differences were also found in how entrained subjects' moods were to this weekly rhythm. We predicted that extraverts (compared with introverts) should be less entrained to a weekly cycle. Results suggest that the novelty- and sensation-seeking behavior of extraverts most likely serves to lessen the cyclical predictability of their day-to-day moods. The origin and psychological meaning of the 7-day week are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
89.
Egbert Woelk Holger Jürgensen Randy Rolph Tim Zielinski 《Journal of Electronic Materials》1995,24(11):1715-1718
We use low pressure MOVPE to grow indium antimonide films on groups of eight 3 inch GaAs wafers per run. The films are used
for the production of magnetoresistive position sensors for the car industry. To meet the narrow specifications for automotive
components, the standard deviation of the sheet resistivity, and the thickness of the films have been reduced below 1.5%.
This uniformity is the result of an optimization process encompassing the determination of the best susceptor temperature
and the optimum flow. The gas velocity was found to have a large impact on the uniformity of the layers. Rotation of the wafers
and the use of an optimum gas velocity results in extremely uniform layers. 相似文献
90.
Rika E. Anderson Alexis D. Ostrowski Danielle E. Gran Jesse D. Fowler Alan R. Hopkins Randy M. Villahermosa 《Polymer Bulletin》2008,61(5):563-568
Summary Various diameters of polyaniline (PANI) nanofibers were easily made by varying the sweep rate in the
electrochemical polymerization of the aniline monomer. At a sweep rate of 5 mV/s, the PANI nanofibers have
an average diameter of 450 nm with a median of 440 nm. The fibers are short, on the order of a few microns
in length, and exhibit a branched geometry. Increasing the sweep rate to 50 mV/s produced longer nanofibers
with a smaller average diameter of 200 nm. Nanofibers synthesized at 100 mV/s were noted to be smaller
with an average and median diameter of 100 nm. These results illustrate the ease in which the morphology
of nanostructured PANI can be altered and indicate that the method has the potential to create multi-diameter
fibers or mixed-morphology materials. 相似文献