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991.
Describes a low-complexity equalization technique for improving the reliability of portable radio links in the presence of multipath time delay spread. A technique that operates on hard-limited received signals, with only the phase information available, is presented. Suboptimum receivers based on a maximum likelihood estimation criterion are discussed, including a sequence estimator and a decision feedback phase detector. A low-complexity adaptive phase equalizer structure using decision-directed phase tracking is proposed. The equalizer does not require the multiplication operations required in most conventional equalization algorithms. The author also proposes a receiver that includes a time-reversal structure and a joint estimator for optimum timing recovery and equalizer training. The time-reversal structure plays a crucial role in maximizing the compensation capability of the phase equalizer. The combined use of phase equalization and diversity reception is also considered 相似文献
992.
The present experiments examined several strategies designed to reduce interval overconfidence in group judgments. Results consistently indicated that 3–4 person nominal groups (whose members made independent judgments and later combined the highest and lowest of these estimates into a single confidence interval) were better calibrated than individual judges and interactive groups. This pattern held even when participants were directly instructed to expand their interval estimates, or when interactive groups appointed a devil's advocate or explicitly considered reasons why their interval estimates might be too narrow. Interactive groups did not perform substantially better than individuals, although participants frequently had the impression that group judgments were far superior to individual judgments. This misperception resembles the "illusion of group effectivity" found in brainstorming research. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
993.
Gradient interpenetrating polymer networks 总被引:5,自引:0,他引:5
The methods of synthesis and properties of gradient interpenetrating polymer networks (IPN) are discussed based on literature
and authors' own experimental data. Gradient IPN can be treated as a sequence of an infinite number of layers of IPNs, whose
composition and properties vary gradually from the surface to the core of specimens. These are analysed the most important
properties of gradient IPNs: temperature transitions, thermodynamic and physico-mechanical characteristics and the main direction
of practical application of gradient IPN-based materials. 相似文献
994.
The successful use of palladium ion implantation into polyimide to seed an electroless plated film of copper on the polyimide surface is reported. Polyimide (Hitachi PIX 3400) was implanted with palladium ions to doses of 1.5 × 1015 − 1.2 × 1017 ions cm−2 using a MEVVA ion implanter. The implanted ions acted as sites for nucleation of copper film. A copper film was then deposited on implanted polyimide using a commercial electroless plating solution. The ion energy was kept low enough to facilitate a low critical ‘seed’ threshold dose that was measured to be 3.6× 1016 Pd ions cm−2. Test patterns were made using polyimide to study the adaptability of this technique to form thick structures. Plated films were studied with optical microscopy, Rutherford Backscattering Spectrometry (RBS) and Profilometry. The adhesion of films was qualitatively assessed by a ‘scotch tape test’. The film growth (thickness) was observed to be linear with plating time. A higher implantation dose led to greater plating rates. The adhesion was found to improve with increasing dose. 相似文献
995.
J. M. Criado M. J. Dianez F. Gotor C. Real M. Mundi S. Ramos J. DEL Cerro 《Ferroelectrics Letters Section》1992,14(3):79-84
The Constant Rate Thermal Analysis method has been used under different experimental conditions to obtain barium titanate powder of very small grain size. Both a crystallographic and a dielectric study ham been carried out on samples sintered at different temperatures. It is deduced that the formation of small coherently diffracting domains is improved by the generation of oxygen vacancies and the cubic phase stabilization depends on the coherently diffracting domain size rather than on the particle size. 相似文献
996.
The strength values obtained in four series of bend tests on two monolithic ceramic materials have been statistically evaluated. Statistical mapping procedures were used to check whether a Weibull distribution fits the strength data. Where this has been found to be the case, the value of the Weibull parameters determined according to different evaluation methods fall within each other's confidence interval. The values of the modulus m and of the characteristic strength σ0 of the two-parameter distribution can differ significantly from the corresponding values in the three-parameter distribution. 相似文献
997.
Translated from Khimicheskoe i Neftyanoe Mashinostroenie, No. 1, p. 32, January, 1992. 相似文献
998.
999.
G. V. Martyusha S. A. Semenov T. A. Kartasheva N. V. Zubkova I. A. Timokhin 《Chemistry and Technology of Fuels and Oils》1992,28(8):468-469
Translated from Khimiya i Tekhnologiya Topliv i Masel, No. 8, pp. 29–30, August, 1992. 相似文献
1000.