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161.
基于腔面非注入技术的大功率半导体激光器 总被引:1,自引:0,他引:1
采用腔面电流非注入技术,提高了808nm半导体激光器灾变性光学损伤(COD)阈值。通过腐蚀GaAs高掺杂层的方法,在半导体激光器腔面附近形成电流非注入区,以此来减少腔面处的载流子注入。载流子注入水平的降低,减少了腔面处非辐射复合的发生,因而提高了激光器的灾变性光学损伤阈值。应用电流非注入技术制作的器件的最大输出功率达到3.7W;而应用常规工艺制作的器件的最大输出功率为3.1W。同常规工艺相比,采用该技术使器件的最大输出功率提高了近20%。 相似文献
162.
我国典型地区大气透过率的计算分析 总被引:1,自引:0,他引:1
主要分析了我国典型地区(西北地区、沿海地区及大陆地区)在2~12 µm波段整层透过率与标准大气模式(1976年美国标准大气、中纬度夏季及中纬度冬季)的偏差,并比较分析了上述两种大气模式下的6种主要吸收分子透过率偏差。结果表明:使用标准大气模式计算我国典型地区的整层大气透过率存在一定的偏差,引起我国典型地区透过率与标准大气模式偏差较大的原因来自H2O分子。1976年美国标大气模式计算我国沿海及大陆地区整层大气透过率的最大绝对偏差达到0.40和0.22;中纬度夏季计算我国沿海及大陆地区7月份整层大气透过率的最大绝对偏差达到0.31和0.29;中纬度冬季计算我国西北、沿海地区1月份整层大气透过率的最大绝对偏差达到0.1和0.36。采用标准大气模式计算我国典型地区整层大气透过率存在一定的偏差,在计算时我国区域内的大气透过率必须考虑我国的大气模式。 相似文献
163.
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165.
A typical arbitrary Lagrangian–Eulerian algorithm consists of a Lagrangian step, where the computational mesh moves with the fluid flow; a rezoning step, where the computational mesh is smoothed and repaired in case it gets too distorted; and a remapping step, where all fluid quantities are conservatively interpolated on this new mesh. In single‐material simulations, the remapping process can be represented in a flux form, with fluxes approximated by integrating a reconstructed function over intersections of neighboring computational cells on the original and rezoned computational mesh. This algorithm is complex and computationally demanding – Therefore, a simpler approach that utilizes regions swept by the cell edges during rezoning is often used in practice. However, it has been observed that such simplification can lead to distortion of the solution symmetry, especially when the mesh movement is not bound by such symmetry. For this reason, we propose an algorithm combining both approaches in a similar way that was proposed for multi‐material remapping (two‐step hybrid remap). Intersections and exact integration are employed only in certain parts of the computational mesh, marked by a switching function – Various different criteria are presented in this paper. The swept‐based method is used elsewhere in areas that are not marked. This way, our algorithm can retain the beneficial symmetry‐preserving capabilities of intersection‐based remapping while keeping the overall computational cost moderate. 相似文献
166.
A new trust region algorithm for bound constrained minimization 总被引:7,自引:0,他引:7
We introduce a new algorithm of trust-region type for minimizing a differentiable function of many variables with box constraints. At each step of the algorithm we use an approximation to the minimizer of a quadratic in a box. We introduce a new method for solving this subproblem, that has finite termination without dual nondegeneracy assumptions. We prove the global convergence of the main algorithm and a result concerning the identification of the active constraints in finite time. We describe an implementation of the method and we present numerical experiments showing the effect of solving the subproblem with different degrees of accuracy.This work was supported by FAPESP (Grants 90-3724-6 and 91-2441-3), CNPq, FINEP, and FAEP-UNICAMP. 相似文献
167.
袁修久 《纯粹数学与应用数学》1998,14(3):30-35
证明了用限制经验似然比构造的置信区域的置信概率的阶为O(n^-1),使用Bartlett修正方法将该误差的阶降为O(n^-2)。 相似文献
168.
M. Juy R. Maurel M. Rooryck I. A. Nugroho T. Hariman 《International Journal of Satellite Communications and Networking》1990,8(3):251-256
A campaign of measurements in Indonesia has been carried out according to a co-operation agreement concluded between the Indonesian and French Administrations with the aim of estimating rain attenuation on slant paths. The experiment was planned using two earth-stations, at Cibinong and Padang, both receiving a Ku-band beacon from an INTELSAT V satellite, coupled with rain-rate measurements at a number of sites. Rain-rate statistics are given for several locations in the Indonesian Archipelago. Cumulative distributions of attenuation and simultaneous rain rate, obtained at the earth-stations, are presented. The analysis of the results has led to the proposal of an adaptation of the CCIR attenuation prediction method for low latitudes. 相似文献
169.
燃气轮机总能系统特性模拟与优化的新思路探讨 总被引:4,自引:0,他引:4
符号表a,b时间区限e如燃烧室效率土时间。fco压气机设计效率Gi(t)即时燃料量ti。设计进气温度efto透平设计效率H。燃料热值取。t全工况效率ef。机械效率Ne(t即时功率。压比efe发电效率风设计进气压力1前言对热力系统及其部件特性的研究,前人已作了很多工作,但多以设计工况下的机组的热力性能与经济性来考虑设计和应用选型等问题,由于种种变工况因素,在设计工况下,机组的热力性能参数匹配及其它性能指标可能处于优化区域,而实际运行中,却处于非最佳运行工况。鉴于上述分析,对装置除了解其设计工况的性能外,还必须对其变工况乃… 相似文献
170.
Bicriterion differential games with qualitative outcomes 总被引:1,自引:0,他引:1
Combat games are studied as bicriterion differential games with qualitative outcomes determined by threshold values on the criterion functions. Survival and capture strategies of the players are defined using the notion of security levels. Closest approach survival strategies (CASS) and minimum risk capture strategies (MRCS) are important strategies for the players identified as solutions to four optimization problems involving security levels. These are used, in combination with the preference orderings of the qualitative outcomes by the players, to delineate the win regions and the secured draw and mutual kill regions for the players. It is shown that the secured draw regions and the secured mutual kill regions for the two players are not necessarily the same. Simple illustrative examples are given.This paper is based partially on research supported by the Council of Scientific and Industrial Research, India, through a Research Associateship Grant to the second author. 相似文献