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Recent isotopic analysis of meteorites and interplanetary dust has identified solid-state materials of pre-solar origin. We can now trace the origin of these inorganic grains to the circumstellar envelopes of evolved stars. Moreover, organic (aromatic and aliphatic) compounds have been detected in proto-planetary nebulae and planetary nebulae, which are the descendants of carbon stars. This implies that molecular synthesis is actively happening in the circumstellar environment on timescales as short as several hundred years. The detection of stellar grains in the Solar System suggests that they can survive their journey through the interstellar medium and that they are a major contributor of interstellar grains. 相似文献
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立体视频编码中的关键问题之一就是视差估值.文中利用分层复数吏登变换域相位相关方法进行匹配提出了一种新的视差估值方法.理论分析和仿真试验证明,本文中的方法克服了传统方法的缺点,提高了视差场的平滑度,减少了视差估值的计算负荷. 相似文献
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Solving traveling salesman problems by genetic algorithms 总被引:6,自引:0,他引:6
LIANG Yanchun GE Hongwei ZHOU Chunguang LEE Heow Pueh LIN Wuzhong LIM Siak Piang LEE Kwok Hong 《自然科学进展(英文版)》2003,13(2):135-141
The gene section ordering on solving traveling salesman problems is analyzed by numerical experiments. Some improved crossover operations are presented. Several combinations of genetic operations are examined and the functions of these operations are analyzed. The essentiality of the ordering of the gene section and the significance of the evolutionary inversion operation are discussed. Some results and conclusions are obtained and given, which provide useful information for the implementation of the genetic operations for solving the traveling salesman problem. 相似文献
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Xinmin Li Wangfun Fong Pengfei Kwok Mengsu Yang Patrick C. L. Wong Jiazuan Ni 《科学通报(英文版)》1999,44(4):331-331
Effects of La3+ and Gd3+ on Ca2+ influx were investigated in rat hepatoma H-35 cells by measuring the initial rate of45Ca2+ uptake. It was found that the maximum initial rate of Ca2+ uptake was increased six-to ten-fold at low concentrations of La3+ and Gd3+. Kinetic analyses by measuring the initial rate of Ca2+ influx at different external Ca2+ concentrations indicated the existence of two intracellular exchangeable components in the basal Ca2+ system, with low and high affinities for Ca2+, and only one class of Ca2+ binding sites was observed in the La3+-or Gd3+-treated cells. For high affinity, La3+ and Gd3+ increased both kinetic parametersK
m andV
max of basai Ca2+ influx. La3+ and Gd3+ compete directly with Ca2+ for Ca2+ binding site for low affinity. The kinetics is competitive. 相似文献
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LIN Wuzhong LIANG Yanchun LEE Kwok Hong LIM Siak Piang LEE Heow Pueh 《自然科学进展(英文版)》2003,13(3):219-227
A doubly clamped microbeam actuated by electrostatic force with squeezed gas film damping is a well-known and standard micro-device in microelectromechanical system (MEMS) for many researchers to demonstrate how reduced-order dynamic macromodel is an effective way to faithfully capture the device behaviors. However it still takes time to directly recompute the time-dependant nonlinear terms in macromodels which are generated by a proper orthogonal decomposition (POD) method with Galerkin procedure at every time step during the macromodel simulation. This paper proposes two methods for speeding up the computation of macromodel simulations. In the first method, the computation speedup is achieved based on the concept of precomputation upon the basis functions are available. In the second method, cubic splines approximation is used to interpolate the basis functions and their first and second derivatives, and spatial integration is performed by application of the Gaussian quadrature. Numerical results show both methods could enhance the efficiency of the macromodel simulation compared with our previous computation results 相似文献
46.
The aim of this study explored the importance of colour application on clothing and investigated whether there is a preference of colour on clothing among children under hospital environment. A modified colour associated test based on the Luster Color Test was used to carry out the survey. Fifty child patients aged four to sixteen were asked to look at two specially designed colour cards and to name their preferences and associations on each of the colour. 相似文献
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一种基于种群熵估计的自适应遗传算法 总被引:9,自引:0,他引:9
为获得运行过程中对搜索空间勘探和开采的平衡 ,该文提出了一种基于种群熵估计的参数自适应遗传算法。该算法每一进化代的新种群由保留、繁殖和随机 3部分子种群组成 ,其数量则由相应的参数进行控制。通过引入种群熵的概念对种群内个体的多样性进行度量并使用一种简单的方法对其进行估计以确定各控制参数 ,该算法实现了参数的自适应调节。试验结果表明该算法能够有效协调勘探和开采 ,在处理复杂问题时表现出较高的性能 相似文献