期刊文献+
共找到8篇文章
< 1 >
每页显示 20 50 100
双层弹性点支承连续梁的静力计算 被引量:1
1
作者 邢书珍 《铁道学报》 EI CSCD 北大核心 1994年第1期80-86,共7页
本文提出了一个利用有限单元法计算一个实际的工程结构──双层弹性点支承连续梁的方法。本方法也适用于第一层梁是无限长而第二层梁是有限长的模型的计算。这种模型可以用来计算桥上无缝线路。最后,对于这两种情况(其中包括桥上无缝... 本文提出了一个利用有限单元法计算一个实际的工程结构──双层弹性点支承连续梁的方法。本方法也适用于第一层梁是无限长而第二层梁是有限长的模型的计算。这种模型可以用来计算桥上无缝线路。最后,对于这两种情况(其中包括桥上无缝线路的计算)均给出了具体的算例。 展开更多
关键词 双层弹性 支承 连续梁 静力计算
下载PDF
锗硅双层量子点的光电流特性 被引量:1
2
作者 周浩 蒋最敏 陆昉 《固体电子学研究与进展》 CAS CSCD 北大核心 2002年第4期441-444,共4页
在分子束外延 (MBE)系统上用自组织方式生长了硅基双层锗量子点结构 ,并对样品进行光电流谱的测试。通过调节不同外加偏压来改变量子点中的费米能级位置 ,量子点中载流子所处束缚能级将随之发生变化 ,所得到的光电流谱的峰位也将因此而... 在分子束外延 (MBE)系统上用自组织方式生长了硅基双层锗量子点结构 ,并对样品进行光电流谱的测试。通过调节不同外加偏压来改变量子点中的费米能级位置 ,量子点中载流子所处束缚能级将随之发生变化 ,所得到的光电流谱的峰位也将因此而改变。由光电流谱得到的实验结果与常规的光致发光谱的结果相吻合。与单层锗量子点结构相比 ,双层结构的样品在光电特性上有着明显不同 :光电流谱中 ,在 0 .767e V及 0 .869e V处出现了两个峰 ,分别对应于载流子在不同的量子点层中的吸收。 展开更多
关键词 双层量子 光电流 光致发光谱 分子束外延
下载PDF
双层量子点中的带负电荷激子(英文)
3
作者 黄锦胜 解文方 《广州大学学报(自然科学版)》 CAS 2007年第1期29-33,共5页
利用精确对角化方法,研究了抛物势双层量子点中带负电荷激子的1S态和3P态的关联能与量子点的束缚势大小的变化关系,以及1S态对应几个不同的量子点间点与点的距离的束缚能随束缚势大小的变化关系,计算了电子与空穴质量比为σ=0.677和σ=0... 利用精确对角化方法,研究了抛物势双层量子点中带负电荷激子的1S态和3P态的关联能与量子点的束缚势大小的变化关系,以及1S态对应几个不同的量子点间点与点的距离的束缚能随束缚势大小的变化关系,计算了电子与空穴质量比为σ=0.677和σ=0.197的缚能随束缚势大小的变化关系. 展开更多
关键词 双层量子 带负电荷激子 关联能 束缚能
下载PDF
一种有效的快速细化算法 被引量:5
4
作者 杨兴炜 刘文予 白翔 《小型微型计算机系统》 CSCD 北大核心 2006年第7期1343-1346,共4页
提出一种有效的快速细化算法,包括两个步骤:首先通过建立w e igh t-va lue的概念对模板进行分类,然后按照分类后的模板对象素进行删除,使之成为由双层点或单层点构成的子图像;为保证能将双层点细化为单层点,提出两个模板,依据这两个模... 提出一种有效的快速细化算法,包括两个步骤:首先通过建立w e igh t-va lue的概念对模板进行分类,然后按照分类后的模板对象素进行删除,使之成为由双层点或单层点构成的子图像;为保证能将双层点细化为单层点,提出两个模板,依据这两个模板进行并行细化从而得到单象素骨架.实验证明这个方法是快速有效的. 展开更多
关键词 细化 模板 双层点 weight—value
下载PDF
导电膜片叠层型电磁屏蔽胶合板的性能研究 被引量:3
5
作者 卢克阳 傅峰 +2 位作者 蔡智勇 付跃进 张耀明 《建筑材料学报》 EI CAS CSCD 北大核心 2011年第2期207-211,233,共6页
基于谢昆诺夫、瓦陶林多层屏蔽理论基础,参照夹层复合屏蔽体模型提出了叠层型电磁屏蔽胶合板结构模型,采用自制导电膜片与木质单板叠层复合制备新型电磁屏蔽胶合板.结果表明:单、双层导电膜片叠层胶合板电磁屏蔽效能随着导电膜片铜纤... 基于谢昆诺夫、瓦陶林多层屏蔽理论基础,参照夹层复合屏蔽体模型提出了叠层型电磁屏蔽胶合板结构模型,采用自制导电膜片与木质单板叠层复合制备新型电磁屏蔽胶合板.结果表明:单、双层导电膜片叠层胶合板电磁屏蔽效能随着导电膜片铜纤维填充量的增大而增大,当铜纤维填充量为200.0 g/m2时,双层导电膜片叠层胶合板电磁屏蔽效能为39.30~61.75 dB,平均值为49.65dB,电磁屏蔽效果中等.试验还表明:在总填充量相同的条件下,随着铜纤维填充量的增大,双层导电膜片叠层胶合板电磁屏蔽效能达到填充量双层屏蔽逆转点后减小,在填充量双层屏蔽逆转点,铜纤维填充量为50.0 g/m2. 展开更多
关键词 导电膜片 叠层型 电磁屏蔽胶合板 双层屏蔽逆转
下载PDF
A TWO-LAYER RECURRENT NEURAL NETWORK BASED APPROACH FOR OVERLAY MULTICAST
6
作者 Liu Shidong Zhang Shunyi Zhou Jinquan Qiu Gong'an 《Journal of Electronics(China)》 2008年第2期209-217,共9页
Overlay multicast has become one of the most promising multicast solutions for IP network,and Neutral Network(NN) has been a good candidate for searching optimal solutions to the constrained shortest routing path in v... Overlay multicast has become one of the most promising multicast solutions for IP network,and Neutral Network(NN) has been a good candidate for searching optimal solutions to the constrained shortest routing path in virtue of its powerful capacity for parallel computation. Though traditional Hopfield NN can tackle the optimization problem,it is incapable of dealing with large scale networks due to the large number of neurons. In this paper,a neural network for overlay multicast tree com-putation is presented to reliably implement routing algorithm in real time. The neural network is constructed as a two-layer recurrent architecture,which is comprised of Independent Variable Neurons(IDVN) and Dependent Variable Neurons(DVN) ,according to the independence of the decision variables associated with the edges in directed graph. Compared with the heuristic routing algorithms,it is characterized as shorter computational time,fewer neurons,and better precision. 展开更多
关键词 Neural Network (NN) NEURON Multicast Overlay network Constrained term Inde-pendent variables
下载PDF
Optimization and characterization of nimesulide bilayer tablets by response surface methodology 被引量:1
7
作者 单利 范云周 +3 位作者 王玉丽 陈红鸽 高春生 杨美燕 《Journal of Chinese Pharmaceutical Sciences》 CAS CSCD 2014年第2期89-93,共5页
The objectives of this present investigation were to develop and formulate nimesulide bilayer tablets by using different polymer combinations and fillers, to optimize the formulations for different drug release variab... The objectives of this present investigation were to develop and formulate nimesulide bilayer tablets by using different polymer combinations and fillers, to optimize the formulations for different drug release variables by orthogonal design and central composite design-surface methodology and to evaluate drug release pattern of the optimized product. The bilayer tablet containing a fast release layer(FRL) and a sustained release layer(SRL) provided an initial burst release of nimesulide, followed by the sustained release for a period of time. The optimal formulation obtained was as follows:(I) the formulation of FRL: nimesulide, 50 mg; lactose, 92 mg; starch, 22 mg; CCMC-Na, 14 mg; PVP K30, 1 mg; micronized silica gel, 1 mg; magnesium stearate, 0.9 mg; and iron oxide red, 0.1 mg; and(II) the formulation of SRL: nimesulide, 150 mg; HPMC K100LV, 26 mg; HPMC K4M, 33 mg; lactose, 54 mg; PVP K30, 1 mg; micronized silica gel, 1 mg; and magnesium stearate, 0.9 mg. According to the optimal formulation, the biphasic type of release was identified. The in vitro drug dissolution from the bilayer tablets was sustained for about 16 h after releasing 15% of drug in the first 10 min. The developed nimesulide bilayer tablets with improved efficacy can perform therapeutically better than the conventional tablets. 展开更多
关键词 NIMESULIDE Bilayer tablets Orthogonal design Central composite design-response surface methodology Sustainedrelease Fast release
原文传递
Location and Design Decisions of Facilities in a Distribution System with Elastic Customer Demand
8
作者 王雪峰 《Journal of Shanghai Jiaotong university(Science)》 EI 2009年第5期606-612,共7页
This paper describes a bi-level programming model that seeks to simultaneously optimize location and design decisions of facilities in a distribution system in order to realize company's maximal total profit subje... This paper describes a bi-level programming model that seeks to simultaneously optimize location and design decisions of facilities in a distribution system in order to realize company's maximal total profit subject to the constraints on the facility capacity and the investment budget.In the upper-level problem,twoechelon integrated competitive/uncompetitive capacitated facility location model,which involves facility location and design,is presented.In the lower-level problem,customer is assumed to patronize store based on facility utility which is expressed by service time cost in the store and its travel cost to customer.Customer's facility choice behavior is presented by a stochastic user equilibrium assignment model with elastic demand.Since such a distribution system design problem belongs to a class of NP-hard problem,a genetic algorithm(GA)-based heuristic procedure is presented.Finally,a numerical example is used to illustrate the application of the proposed model and some parameter sensitivity analyses are presented. 展开更多
关键词 facility location facility design distribution system bi-level programming
原文传递
上一页 1 下一页 到第
使用帮助 返回顶部