潜土旋耕试验研究(2)──逆转旋耕抛土刀片试验研究

本文通过在室内土槽试验台上对抛土刀片的试验,讨论了刀片几何参数及运动参数对旋耕扭矩的影响,在大量试验的基础上提出了抛土刀片的几个主要参数的参考值．     

出口鼓励政策效果评测模型及应用

探讨了建立出口鼓励政策效果评测模型的理论基础,运用虚变量回归分析技术建立了实际模型,用于中国工业制成品出口鼓励政策效果的评测,对模型实用性进行了验证,并对测算结果进行了实证分析。     

远极比三速感应电动机多极时的性能计算

根据远极比三速感应电动机多极时特点,在现有电机电磁计算程序珠基础上,提出了多极时改进的等效电路和性能计算方法。通过算例与样机试验结果的对比,其计算精度优于其他的计算方法。     

金属钝化曲线的测定实验的改进研究

采用线性电位扫描法测定镍在硫酸溶液中钝化行为。与以往的实验不同之处是使用CHI系列电化学工作站如CH1660A代替JH2X型数字式恒电位仪，实验表明：不但实验的速度有明显提高；而且可大大减少数据处理引入的误差。     

聚碳硅烷/二乙烯基苯与聚硅烷/二乙烯基苯的交联与裂解

以二乙烯基苯(DVB)作为交联剂的聚碳硅烷(PCS)／二乙烯基苯(DVB)和聚硅烷(PS)／二乙烯基苯(DVB)两种体系来制备SiC陶瓷．对比了DVB加入量对于交联状态、陶瓷产率的影响，用SEM观察裂解样品的微观结构，用XRD研究了裂解样品的相组成．实验结果表明：PS／DVB体系的陶瓷产率高于PCS／DVB体系；且PS／DVB体系的陶瓷微观结构比PCS／DVB体系致密；其XRD分析表明所得陶瓷含β-SiC．     

10万亿次巨型机

巨型机是国家信息基础的核心设备，高性能计算技术及应用水平被认为是一个国家综合国力的重要标志，国与国之间的较量实际上是综合国力的较量，开发具有我国自主产权的巨型机成为当前我国计算机产业的重要任务。文章就国产巨型机产业化状况及巨型机应用范围做了简要介绍。     

基于分数阶位置状态的量子粒子群算法

由量子力学的概念和粒子群优化算法的结合,量子行为粒子优化算法作为粒子群算法的一个变种,具有更好的全局搜索能力.为了提高量子粒子算法的全局搜索能力,结合分数阶微积分的概念,本文提出了一种新的算法.该算法将分数阶微积分中常用的GL定义引入了量子粒子算法的更新迭代公式中,利用分数阶微积分的长时记忆特性,通过记忆量子粒子在更新迭代过程中的历史位置和历史信息,增强算法的收敛速度和收敛精度.为了全面评估算法的基本性能,本文进行了一些关于基本测试函数的功能测试.通过对于不同阶次的分数阶量子粒子算法的对比实验和与其他粒子群改进算法的对比实验,实验结果表明,该算法具有更高的收敛精度.     

Structure prediction for the down state of a potassium channel voltage sensor

Voltage-gated potassium (Kv) channels, essential for regulating potassium uptake and cell volume in plants and electrical excitability in animals, switch between conducting and non-conducting states as a result of conformational changes in the four voltage-sensing domains (VSDs) that surround the channel pore. This process, known as gating, is initiated by a cluster of positively charged residues on the fourth transmembrane segment (S4) of each VSD, which drives the VSD into a 'down state' at negative voltages and an 'up state' at more positive voltages. The crystal structure of Kv1.2 probably corresponds to the up state, but the local environment of S4 in the down state and its motion in voltage gating remains unresolved. Here we employed several conditional lethal/second-site suppressor yeast screens to determine the transmembrane packing of the VSD in the down state. This screen relies on the ability of KAT1, a eukaryotic Kv channel, to conduct potassium when its VSDs are in the down state, thereby rescuing potassium-transport-deficient yeast. Starting with KAT1 channels bearing conditional lethal mutations, we identified second-site suppressor mutations throughout the VSD that recover yeast growth. We then constructed a down state model of the channel using six pairs of interacting residues as structural constraints and verified this model by engineering suppressor mutations on the basis of spatial considerations. A comparison of this down state model with the up state Kv1.2 structure suggests that the VSDs undergo large rearrangements during gating, whereas the S4 segment remains positioned between the central pore and the remainder of the VSD in both states.     

An Analysis of International Data Encryption Algorithm（IDEA） Security against Differential Cryptanalysis

The security of international date encryption algorithm （IDEA（16））, a mini IDEA cipher, against differential cryptanalysis is investigated. The results show that [DEA（16） is secure against differential cryptanalysis attack after 5 rounds while IDEA（8） needs 7 rounds for the same level of security. The transition matrix for IDEA（16） and its eigenvalue of second largest magnitude are computed. The storage method for the transition matrix has been optimized to speed up file I/O. The emphasis of the work lies in finding out an effective way of computing the eigenvalue of the matrix. To lower time complexity, three mature algorithms in finding eigenvalues are compared from one another and subspace iteration algorithm is employed to compute the eigenvalue of second largest module, with a precision of 0.001.     

中国期刊全文数据库引文检索方法和效果探析

中国期刊全文数据库（简称CJFD）引文检索功能之强大在国内的全文数据库中无以伦比,但也存在一些需要改进的地方：检索项缺少被引机构检索字段,故不能以被引机构进行入口检索或限制检索范围;检索结果缺少统计分析功能,致使引文检索结果不易甄别和统计．建议：（1）引文著录增加引文机构项,以便提供检索点;（2）CJFD检索项增加被引机构检索字段,以使引文检索更加便捷高效;（3）增加引文统计分析功能,节省检索者分析、筛选、甄别信息的时间;（4）完善检索结果显示,检索结果既能反映引用文献信息,又能反映被引文献信息．