Prediction of eukaryotic gene structures based on multilevel optimization

Computational gene structure prediction, which is valuable for finding new genes and understanding the composition of genomes, plays a very important role in various kinds of genome projects. For eukaryotic gene structures, however, the prediction accuracy of existing methods is still limited. This paper presents a method of predicting eukaryotic gene structures based on multilevel optimization. The complicated problem of predicting gene structure in eukaryotic DNA sequence containing multiple genes can be decomposed into a series of sub-problems at several levels with decreasing complexity, including the gene level (single-exon gene, multi-exon gene), the element level (exon, intron, etc.), and the feature level (functional site signals, codon usage preference, etc.). On the basis of this decomposition, a multilevel model for the prediction of complex gene structures is created by a multilevel optimization process, in which the models dealing with sub-problems at low complexity level are first optimized respectively, and then optimally combined together to form models for those sub-problems at higher complexity level. Based on the multilevel model, a dynamic programming algorithm is designed to search for optimal gene structures from DNA sequences, and a new program GeneKey (1.0) for the prediction of eukaryotic gene structures is developed. Testing results with widely used datasets demonstrate that the prediction accuracies of GeneKey (1.0) at the nucleotide level, exon level and gene level are all higher than that of the well known program GENSCAN. A web server of GeneKey(1.0) is available at http://infosci.hust.edu.cn     

正态分布和t分布下风险价值计算的对比研究

针对金融数据的尖峰、厚尾性，先在单变量情形下用经验贝叶斯方法得出正态分布和t分布下风险价值(VaR)的计算公式，然后探讨了当金融数据服从多变量分布时，应用delta-gamma二次近似法，分别得出正态分布和t分布下的组合VaR计算方法，从而为解决厚尾问题提供了基础。     

基于模糊逻辑的感应电动机直接矢量控制系统

为了提高感应电动机直接矢量控制系统对参数变化和负载扰动的鲁棒性，提出并设计了两种模糊逻辑控制器分别对系统的速度和磁链进行控制，速度和磁链控制器的结构均为模糊PI型，优化模糊控制器的隶属函数分布以增强其控制性能，结果表明它们能明显改善系统的动态和静态性能。     

遗传算法在陀螺温控系统中的应用研究

由于惯性导航系统中陀螺受到温度的影响,故常采用温控系统来控制陀螺的温度,以保持陀螺的精度与性能。为了获得更好的控制效果,本文提出了用遗传算法来优化温控系统PID参数的具体算法,计算机仿真结果表明,该法是一种行之有效的方法。     

一种简易被动声直升机定位系统

利用简易被动声传感器阵列进行直长升机目标定位。定位系统由４个成平面上四边形的声传器阵列,多通道声信号同步采集器和ＴＭＳ３２０高速信号处理器,随动控制系统构成。     

木糖醇发酵液脱色的优化工艺

根据木糖醇发酵脱色实验,借助均匀设计法,确定人工神经网络的隐层神经元数、学习速度和动量因子等模型参数,构建一个能用于预测、优化木糖醇发酵液脱色过程的３层数学模型（５－８－１）,并通过遗传上算法寻优,获得效果更好的脱色工艺。     

负偏压增强离子表面扩散机制

对利用热灯丝ＣＶＤ沉积金刚石膜时负衬底偏压强金刚石的核化过程进行了分析。结合等离子体和碰撞等有关理论,从理论上初步地研究了负衬底偏压对增强活性离子沿衬底表面扩散的影响,给出了扩散九,扩散距离与负底偏压之间的关系。结果表明扩散系数和扩散距离都随着负衬底偏压的增大而增大。     

县域"三高"农业发展规划中的系统动力学仿真应用--以东源县为例

应用系统动力学理论建立了东源县"三高"农业发展规划的SD模型,对东源县1996～2010年的"三高"农业发展进行了动态仿真,依据仿真结果,制订了规划目标.表6,参4.     

铅锶共沉淀络合滴定法测定铜合金中的铅

介绍了利用铅锶共沉一络合滴定法测定铜合金中的铅,试样以硝酸溶解,用硝酸锶共沉淀铅,将沉淀溶于热稀硝酸溶液中,在pH值为5．5的弱酸性介质中,以二甲酚橙为指示剂,EDTA滴定铅,结果满意．     

Nanostructure. Epitaxial diamond polytypes on silicon

Carbon is unique in the variety of configurations it can adopt with itself and other elements. Here we show how ion beams can be used to nanostructure various diamond polytypes, epitaxially aligning them to a silicon substrate. The ready controllability of ion beams, which are already used to manufacture submicrometre-scale devices, means that our findings should enable new carbon and non-carbon materials to be nanostructured for a host of applications.