Gaussian process assisted coevolutionary estimation of distribution algorithm for computationally expensive problems

In order to reduce the computation of complex problems, a new surrogate-assisted estimation of distribution algorithm with Gaussian process was proposed. Coevolution was used in dual populations which evolved in parallel. The search space was projected into multiple subspaces and searched by sub-populations. Also, the whole space was exploited by the other population which exchanges information with the sub-populations. In order to make the evolutionary course efficient, multivariate Gaussian model and Gaussian mixture model were used in both populations separately to estimate the distribution of individuals and reproduce new generations. For the surrogate model, Gaussian process was combined with the algorithm which predicted variance of the predictions. The results on six benchmark functions show that the new algorithm performs better than other surrogate-model based algorithms and the computation complexity is only 10% of the original estimation of distribution algorithm.     

浅议全球化背景下的城市定位与城市竞争力

一、问题的由来 城市定位，一个决定中国城市发展命运的主题。自20世纪90年代以来，经济的一体化和全球化突飞猛进，竞争日趋激烈。而经济一体化和全球化，使城市的作用变得日益突出——换言之，国家竞争力更多体现在城市竞争力上。与此同时，经济一体化和全球化引起的国际分工，导致了城市分工。因此，在全球化背景下，城市要实现最优化发展，必须扬长补短，对城市进行准确定位，并制定竞争和发展战略。     

~(19)F(p,αγ)~(16)O瞬发核反应测定茶叶中的含氟量

本文介绍了在400kV高压倍加器上,利用~(19)F(p,αγ)~(16)O瞬发核反应测量国内150余种茶叶样品含氟量的原理及实验装置,给出了一批典型的测量结果。结果表明:同一品种的茶叶,茶的品级数越大,含氟量越高;茶叶的品种越好,含氟量越低。     

Performance of N95 elastomeric respirators in high humidity and high coal dust concentration environmentOA

High humidity and high dust concentration in deep coal mines may severely challenge the performance of respirators worn by coal miners.This paper aims at quantitatively evaluating the respirators used in deep coal mines and providing scientific guidance for the respiratory protection of miners.Based on the self-designed in-situ PM_2.5collector,controllable PM_2.5generator,human breathing simulator,and respirator simulation testing system,under the simulated deep mine working ...     

氧化混凝法处理苎麻脱胶煮炼废水的试验研究

探讨了以Fenton试剂和石灰对苎麻脱胶煮炼废水进行氧化混凝处理的方法.试验表明,当FeSO4·7H20、H2O2(质量分数30%)、饱和石灰乳的投加量分别为3 g/L、3 mL/L和4 mL/L时,CODcr的去除率>50%,色度去除率>90%.更重要的是,处理后出水可部分回用于煮炼生产,从而节约生产用碱量,减少废水排放量,还可提高废水可生化性,为后续生物处理创造条件.该处理方法是一种清洁生产处理方法,具有较广阔的应用前景.     

水电站零压起动和变频技术在线路融冰中的应用

通过理论计算和现场在用的设备相结合,利用小水电站零电压起动、变频,均压起励的方法融冰取得良好、效果。     

High-speed ground moving target detection research using triangular modulation FMCW

The frequency modulated continuous wave (FMCW) radar has the characteristics of low probability of interception, good hidden property and the ability to counter anti-radiation missiles. This paper proposes a new method for high-speed ground moving target detection (GMTD) using triangular modulation FMCW. According to the characteristic of the opposite range shift induced by the upslope and downslope modulation FMCW, the upslope and downslope are imaged, respectively. After compensation of continuous motion of the platform and time difference between upslope and downslope signals for imaging, the moving target can be detected through displaced phase center antenna (DPCA) technology. When the moving target is detected, the moving target image is extracted, and correlation processing is used to obtain the range shift, which can be used to estimate the target radial velocity, and further to find the real position of the target. The effectiveness of this method is verified by the result of computer simulation. __________ Translated from Journal of Xidian University, 2008, 35(4): 586–591 [译自: 西安电子科技大学学报(自然科学版)]     

TC4合金锥体模锻过程的数值模拟

采用刚塑性有限元法对钛合金锥体的模锻成形进行有限元数值模拟,分析了锥形件模锻过程中的金属流动规律,应力场、应变场、变形区的压力分布,压力的变化规律等。模拟结果表明,锥体模锻成形分为3个阶段:初期变形过程是圆柱体变形为一个小曲率壳体的阶段,应力主要集中在上模的正下方,应变主要发生在此变形区;变形中期是与下模相接触的部分参与变形的体积逐渐增大,直至最后形成所需要的锥体形状;变形后期由于摩擦作用产生严重的不均匀壁厚减薄现象。     

机械合金化Cu－5Cr合金的组织性能研究

研究了机械合金化制粉、热静液挤压致密制备的Ｃｕ－５Ｃｒ合金的组织与性能。机械合金化Ｃｕ－５Ｃｒ合金由于细晶强化和弥散强化的作用，具有很高的强度（σｂ≥７５０ＭＰａ），经热处理后，合金具有较高的延伸率（δ≥８％）和导电性（≥６０％ＩＡＣＳ）。材料晶粒达到０．１μｍ级，析出的Ｃｒ粒子达到纳米级。     

高校学生欠费现象浅析

高校学生欠费是近几年来困扰高校发展的一个难题。分析指出家庭经济困难、学费标准偏高、学生诚信缺失是欠费现象形成的主要原因。提出国家应加大高等教育投入、高校应加大贫困大学生资助力度、大学生要加强自身诚信修养等解决欠费问题的对策措施。