PLC提高性实验的实验教学改革探索

介绍PLC即可编程序控制器在实验教学中进行的提高性实验,提高性实验之一是PLC对三台鼠笼异步电动机的自动与手动控制,PLC指令的灵活应用及实现。     

Researches on the computer digital control system of giant magnetostrictive actuator

In this paper, a computer digital control system of giant magnetostrictive actuator (GMA) was designed. In GMA system, driving magnetic field was provided by variable magnetic field generated by exciting coil current and offset magnetic field generated by permanent magnet. And Terfernol-D was used as the giant magnetostrictive materials (GMM). GMA’s control model was analysed and the whole control system was established. In the computer digital control system, the control core were single-chip microcomputer and PC with modularization thinking. And the control algorithm was PID. Design for system’s hardware and software was completed and software package was developed. Experiment shows that the GMA system is controlled automatically and monitored real-time. It lays a foundation of further improving control precision of GMA, improving the entire system’s dynamic characteristics and realizing automatic control.     

抽油机悬点载荷计算图版的数学模拟

美国石油学会公式是计算抽油机悬点载荷常用的公式之一,在该公式中,有两个无因次参数需要人工读图才能够查出。利用图像识别技术读取图版曲线上的数据点,对曲线进行数学模拟,使其能方便地应用于工程计算之中。     

基于遗传算法的飞行器路径规划研究

提出一种基于遗传算法和B-样条曲线的路径规划新方法。以B-样条曲线控制点的坐标作为遗传因子用遗传算法进行规划,根据这些控制点,运用B-样条曲线在3维坐标系中生成飞行器路径轨迹。由于只对控制点进行规划减小了系统的计算量,极大地提高了系统的实时性。仿真表明运用该算法规划的路径可以以最优的轨迹把飞行器指引到预定的目的地。     

铝基复合材料结构遥感器设计分析

空间遥感器光学反射镜的高刚度、支撑结构的合理性以及良好的热尺寸稳定性是保证其成像的关键因素。遥感器的重量对于运载平台也是至关重要的。针对这些问题,提出一种支撑杆的连接方式,能够减轻遥感器的重量。反射镜和背板采用高体份铝基复合材料,不仅保证高度、强度,而且因采用同一种材料从而避免了热环境对遥感器结构变形的影响。通过采用有限元仿真分析,在重力和10°温升情况下各反射镜的面形PV值〈55nm,满足〈1/10λ（λ=632.8nm）指标要求,整个结构的前三阶模态为115Hz,120Hz,203Hz。结果表明,采用支撑杆以及铝基复合材料的遥感器结构能够满足空间环境要求,为进一步工程应用提供了理论依据。     

适于自动绕簧机的床用钢丝生产工艺

选用优质盘条,按含碳量分组投料,经铅浴处理后拉制成所需的床用弹簧钢丝,通条性能均匀,线盘平整度好。这样的钢丝在自动绕簧机上绕制性能好,材料消耗低,生产效率高,绕制弹簧的质量好     

Cryptographic Hash Functions from Expander Graphs

We propose constructing provable collision resistant hash functions from expander graphs in which finding cycles is hard. As examples, we investigate two specific families of optimal expander graphs for provable collision resistant hash function constructions: the families of Ramanujan graphs constructed by Lubotzky-Phillips-Sarnak and Pizer respectively. When the hash function is constructed from one of Pizer’s Ramanujan graphs, (the set of supersingular elliptic curves over with ℓ-isogenies, ℓ a prime different from p), then collision resistance follows from hardness of computing isogenies between supersingular elliptic curves. For the LPS graphs, the underlying hard problem is a representation problem in group theory. Constructing our hash functions from optimal expander graphs implies that the outputs closely approximate the uniform distribution. This property is useful for arguing that the output is indistinguishable from random sequences of bits. We estimate the cost per bit to compute these hash functions, and we implement our hash function for several members of the Pizer and LPS graph families and give actual timings.     

使用提前放闪电避雷针对短波测向天线场直击雷防护

本文对短波测向天线场直击雷防护的几种方法进行分析,提出了一种使用提前放闪电避雷针进行天线场直击雷防护的简单实用方法。     

InGaAsP／InP异质结构材料X射线衍射摇摆曲线中的干涉指纹研究

双晶衍射摇摆曲线的全面分析需用计算机模拟高木方程能得到，其信息广但不直观。本文讨论了ＭＯＣＶＤ外延片Ｘ射线衍射中的干涉指纹，指出了用干涉指纹测试簿膜厚度的精确性，讨论了干涉指纹出现的一些特征，使能直观地得到一些外延片的结构信息，为识别和正确使用干涉指纹估算簿层厚度提供依据。     

Index Calculus in Class Groups of Non-hyperelliptic Curves of Genus Three

We study an index calculus algorithm to solve the discrete logarithm problem (DLP) in degree 0 class groups of non-hyperelliptic curves of genus 3 over finite fields. We present a heuristic analysis of the algorithm which indicates that the DLP in degree 0 class groups of non-hyperelliptic curves of genus 3 can be solved in an expected time of . This heuristic result relies on one heuristic assumption which is studied experimentally. We also present experimental data which show that a variant of the algorithm is faster than the Rho method even for small group sizes, and we address practical limitations of the algorithm.