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991.
992.
This paper presents an algorithm for finding a global minimum of a multimodal, multivariate and nondifferentiable function. The algorithm is a modification to the new version of the Price’s algorithm given in Brachetti et al. [J. Global Optim. 10, 165–184 (1997)]. Its distinguishing features include: (1) The number-theoretic method is applied to generate the initial population so that the points in the initial population are uniformly scattered, and therefore the algorithm could explore uniformly the region of interest at the initial iteration; (2) The simplified quadratic approximation with the three best points is employed to improve the local search ability and the accuracy of the minimum function value, and to reduce greatly the computational overhead of the algorithm. Two sets of experiments are carried out to illustrate the efficiency of the number-theoretic method and the simplified quadratic model separately. The proposed algorithm has also been compared with the original one by solving a wide set of benchmark problems. Numerical results show that the proposed algorithm requires a smaller number of function evaluations and, in many cases, yields a smaller or more accurate minimum function value. The algorithm can also be used to deal with the medium size optimization problems. 相似文献
993.
研究了ZnO-Bi2O3系压敏陶瓷等效势垒高度eff随着归一化电压的变化规律,发现等效势垒高度eff随着归一化电压的增加先逐渐增大,达到最大值后持续下降.由于在外加电压作用下反偏势垒高度高于正偏势垒高度,等效势垒高度eff主要取决于反偏势垒.因此,这种变化规律说明了ZnO压敏陶瓷晶界的导电过程可能存在三个阶段.在低归一化电压区,晶界区域中的电子从正偏势垒区注入到晶界无序层的速率低于电子从晶界无序
关键词:
ZnO压敏陶瓷
归一化电压
等效势垒高度
导电过程 相似文献
994.
Q.-H Chen Y.-H. Ren Z.-K Jiao 《The European Physical Journal B - Condensed Matter and Complex Systems》1998,3(3):307-313
The general properties of one-dimensional large Fr?hlich polarons in motion are investigated with the previous extended coherent
states where two-phonon correlations are considered. As a result, the polaron energy, velocity, effective mass, and average
number of virtual phonons as a function the polaron total momentum are evaluated in a wide range of the coupling constant.
In addition, rich information about virtual phonons emitted by the electron in motion is obtained. More importantly, some
intrinsic features of 1D moving polarons are presented for the first time, which may also be suited to moving polarons in
more than one dimensions.
Received: 23 October 1997 / Revised and Accepted: 27 January 1998 相似文献
995.
By using of the invariant theory, we have studied the phase of two-body Bose-Einstein condensates with collision, the dynamical
and geometric phases are presented respectively. The Aharonov-Anandan phase is also obtained in the case of considering the
cyclical evolution. 相似文献
996.
Hongbin Wang Fangfang Ge Hongjie Liu Guoquan Ni Xiangdong Yang Yuqiu Gu Xianlun Wen Weimin Zhou Guangchang Wang Tianshu Wen Yingling He Chunye Jiao Shuanggen Zhang Xiangxian Wang 《中国光学快报(英文版)》2006,4(5)
A deuterium cluster jet produced in the supersonic expansion into vacuum of deuterium gas at liquid nitrogen temperature and moderate backing pressures are studied by Rayleigh scattering techniques. The experimental results show that deuterium clusters can be created at moderate gas backing pressures ranging from 8 to 23 bar, and a maximum average cluster size of 350 atoms per cluster is estimated. The temporal evolution of the cluster jet generated at the backing pressure of 20 bar demonstrates a two-plateau structure. The possible mechanism responsible for this structure is discussed. The former plateau with higher average atom and cluster densities is more suitable for the general laser-cluster interaction experiments. 相似文献
997.
998.
研究了正交表矩阵象的不变性,利用正交表矩阵象的不变性有时容易发现并证明两个正交表之间的正交性,并且用例子说明了这种方法的应用. 相似文献
999.
采用电子谱仪测量了飞秒激光-金属薄膜靶相互作用中靶前和靶后产生的超热电子能谱.结果显示:靶前超热电子能谱的峰出现在约430 keV处,靶后超热电子能谱的峰出现在约175 keV处;靶前超热电子的有效温度分别为218 keV和425 keV,靶后超热电子能谱出现“软化”现象,其有效温度分别为96 keV和347 keV.靶前和靶后超热电子能谱明显不同是由于超热电子输运穿越过密等离子体和冷材料的靶,并在靶后建立Debye鞘,鞘电场使靶后超热电子能谱峰向低能端移动,鞘电场和自生磁场导致靶后超热电子能谱产生“软化”,估算出的鞘电场小于激光电场. 相似文献
1000.
Yin Li Chongqing Jiao Jirun Luo 《International Journal of Infrared and Millimeter Waves》2007,28(12):1155-1160
A mode converter with multi-waveguide output for millimeter wave gyro-device applications is proposed in this article, which
is used to convert the TE01 circular waveguide mode into the TE10 rectangular waveguide mode. Computer simulations with Ansoft HFSS code show that the energy transmission coefficient of larger
than 95.96% may be reached in the frequency range from 34.094 GHz to 35.8 GHz (a bandwidth of 1.706 GHz) at a VSWR of lower
than 1.5 for the input operating mode. 相似文献