An optimization algorithm based on stochastic sensitivity analysis for noisy objective landscapes

A function minimization algorithm that updates solutions based on approximated derivative information is proposed. The algorithm generates sample points with Gaussian white noise, and approximates derivatives based on stochastic sensitivity analysis. Unlike standard trust region methods which calculate gradients with n or more sample points, where n is the number of variables, the proposed algorithm allows the number of sample points M to be less than n. Furthermore, it ignores small amounts of noise within a trust region. This paper addresses the following two questions: how does the derivative approximation become worse when the number of sample points is small? Can the algorithm find good solutions with inexact derivative information when the objective landscape is noisy? Through intensive numerical experiments using quadratic functions, the algorithm is shown to be able to approximate derivatives when M is about n/10 or more. The experiments using a formulation of the traveling salesman problem show that the algorithm can find reasonably good solutions for noisy objective landscapes with inexact derivatives information.     

分形图像压缩的信源信道联合编码

本文针对分形图像压缩编码后所得各部分压缩数据的特点，分析了分形图像压缩各部分数据在传输中对传输信道干扰的敏感程度，并根据各部分数据对信道干扰的敏感程度的不同，提出了一种分形图像压缩的信源信道联合编码方法。仿真结果表明，采用所提出的分形图像压缩的信源信道联合编码方法后，分形图像压缩数据对传输信道的敏感程度降低，图像质量有较大提高。     

云南东川泥石流沟与非泥石流沟~(137)Cs示踪法物源研究

运用1 37Cs示踪法调查云南东川小江流域 6条泥石流沟、6条非泥石流沟和主河的泥沙来源。泥沙主要来源于冲沟侵蚀和滑坡崩塌堆积、坡耕地和草地。坡耕地和草地表层土壤1 37Cs平均含量分别为 0 9Bq m2 和1 98Bq m2 ,冲沟沟壁和滑坡崩塌堆积土体1 37Cs。作者通过 3种源地土体1 37Cs含量的比较 ,分析了细粒泥沙(<0 0 1mm)的来源。 6条泥石流沟冲沟侵蚀和重力侵蚀 (滑坡崩塌 )的相对产沙量变化于 90 2 %～ 1 0 0 % ,平均值为 95 1 % ,6条非泥石流沟的相对产沙量变化于 74 5 %～ 83 3% ,平均值为 78 9%。小江主河为 81 4 %。     

减少氮、磷流失的多目标控制排水模型

运用多目标决策技术,减少农田排水氮、磷输出,保持适宜作物生长的土壤含水量,探讨地表控制排水的控制时间。通过田间试验和SPSS回归模拟,应用均值土壤一维垂直入渗Philip公式计算累计入渗量,研究田间尺度降雨排水中氮、磷浓度的变化规律,拟合控制排水氮、磷浓度对数函数模拟方程。建立减少氮、磷流失和排涝、除渍的多目标控制排水模型,提出求解模型的非劣解和均衡解的方法。     

局部散射源参数估计的非线性算子方法

本文利用单次快摄数据的两个非线性算子估计局部散射源中心波达方向和角扩展,与多维参数搜索和其他低复杂性的局部散射源参数估计算法不同,非线性算子方法给出了单次快摄的局部散射源参数估计的闭式解,无需进行多维搜索和子空间分解。     

膜-粉末炭反应器净化微污染源水

采用膜-粉末炭反应器处理微污染源水的试验结果表明,该工艺对水中的有机物具有较好的净化效果,在水温《10℃的条件下,处理可生化性很低的三家店水库水时对CODMn的去除率仍保持在65%左右;工艺对CODMn、UV254、UV410的去除效果依次增强.     

基于约束优化的联想记忆模型学习算法

本文提出了一种对称互连神经元网络的学习策略,利用全局约束优化方法确定连接权。优化过程采用了梯度下降技术。这种学习算法可以保证训练样本成为系统的稳定吸引子,并且具有优化意义上的最大吸引域。本文讨论了网络的存储容量,训练样本的渐近稳定性和吸引域大小。计算机实验结果说明了学习算法的优越性。     

Effect of epitaxial realignment on the leakage behavior of arsenic-implanted,as-deposited polycrystalline Si-on-single crystal Si diodes

When dopants are indiffused from a heavily implanted polycrystalline silicon film deposited on a silicon substrate, high thermal budget annealing can cause the interfacial “native” oxide at the polycrystalline silicon-single crystal silicon interface to break up into oxide clusters, causing epitaxial realignment of the polycrystalline silicon layer with respect to the silicon substrate. Anomalous transient enhanced diffusion occurs during epitaxial realignment and this has adverse effects on the leakage characteristics of the shallow junctions formed in the silicon substrate using this technique. The degradation in the leakage current is mainly due to increased generation-recombination in the depletion region because of defect injection from the interface.     

沈阳太平洋广场空调冷热源方案比较

对一幢１１．５万ｍ＾２的四星级综合建筑的空调冷热源不同的蓄冷和取冷比较了四种方案，论证了其中直燃型溴化锂吸收式冷热水机组供冷供暖、小型燃油锅炉供蒸汽的方案最为合理。     

微机核子秤在大型尿素装置中的应用

介绍了大型尿素装置中微机核子秤的系统构成，测量原理、安装、调校及在调试过程中发现的问题。