自主知识产权是提升国家竞争力的核心

科学技术是第一生产力,自主创新是第一竞争力,只有加强自主知识产权的保护,才能调动和保护人们自主创新的积极性,开发更多更高质量的自主知识产品,提高我国经济的国际竞争力,为我国在国际经济竞争中争取主动权。     

可变时滞系统的控制与仿真

炉温变化时硬质合金真空烧结炉的时滞常数变化很大，常规PID控制不能同时在高温段与低温段满足生产工艺提出的控制品质要求。本文在利用最小二乘法拟合出真空烧结炉时滞常数与炉温变化函数的基础上，PID参数采用经典的CHR整定算法随炉温变化实时整定，并利用MAT—LAB仿真软件对该控制算法在真空烧结炉中的应用进行了仿真研究，结果表明该算法能够实现对真空炉的有效控制，控制系统能够满意地跟踪设定的温度曲线。     

一种用单片机制作的高频正弦波逆变器

本文介绍一种简单廉价的单片机AT89C2051实现正弦波脉宽调制、保护的逆变器电路，以及逆变器的整体设计和工作原理，为小型正弦波逆变器的设计制作提供了一种较新的思路。     

不容忽视的企业建设项目环境管理

本文从企业建设项目环境管理存在的问题入手，剖析了存在问题的类型，介绍了建设项目环境管理制度，提出了建设项目环境管理的对策与建议，强调建设项目环境管理不容忽视。     

PDE造型方法在复杂曲面设计中的应用

研究了偏微分方程曲面造型方法在飞机外形设计中的应用.该飞机模型的机翼具有边条,因而给曲面造型带来一定的困难.本文应用周期PDE曲面片,构造出了机身与机翼之间G1光滑拼接的过渡面.同时,用PDE方法构造出机身与前小翼及尾翼间的过渡面.实践表明,PDE方法在光滑拼接过渡面的设计中简便实用.     

基于VB6.0的PC-单片机多波特率通信检测方法

在PC-单片机分布式多波特率通信系统中．利用微软的MSComm控件、VB6．0编程语言和单片机的定时／记数器可以智能、准确、简单地实现单片机波特率随主机变化而自动检测调整。     

An effective hybrid genetic algorithm for flow shop scheduling with limited buffers

As a typical manufacturing and scheduling problem with strong industrial background, flow shop scheduling with limited buffers has gained wide attention both in academic and engineering fields. With the objective to minimize the total completion time (or makespan), such an issue is very hard to solve effectively due to the NP-hardness and the constraint on the intermediate buffer. In this paper, an effective hybrid genetic algorithm (HGA) is proposed for permutation flow shop scheduling with limited buffers. In the HGA, not only multiple genetic operators based on evolutionary mechanism are used simultaneously in hybrid sense, but also a neighborhood structure based on graph model is employed to enhance the local search, so that the exploration and exploitation abilities can be well balanced. Moreover, a decision probability is used to control the utilization of genetic mutation operation and local search based on problem-specific information so as to prevent the premature convergence and concentrate computing effort on promising neighbor solutions. Simulation results and comparisons based on benchmarks demonstrate the effectiveness of the HGA. Meanwhile, the effects of buffer size and decision probability on optimization performances are discussed.     

Synthesis and characteristics of SiC whiskers with “rosary bead” morphology

SiC whiskers with ″rosary bead″ morphology were synthesized using suitable silicon source and carbon source through solid reaction at the temperature above 1537 K. The diameter and length of the SiC whiskers were about 0.1-1.0 μm and 20-100 μm,respectively. The largest diameter of their enlarged ends of the whiskers was about 0.2-1.0 μm, and it gradually and smoothly decreased to the size of the plain part of the whiskers. The results of X-ray diffraction analysis show that the crystalline structure of the obtained SiC whiskers is β-SiC. It is considered that the SiC whiskers grow via a vapor-solid mechanism.     

建筑装饰工程概预算课程教学改革探讨

建筑装饰工程概预算课程是环境艺术设计专业的一门重要专业课。针对我国现行工程量清单计价模式的特点,结合目前教学中存在的问题,从教学内容、教学方法等多方面提出了该课程教学改革的基本思路,探讨了建筑装饰工程概预算课程教学的新模式。     

基于人工神经网络的原油触变特性参数计算

基于Levenberg-Marquardt算法的前馈BP网络的原油触变特性参数计算方法,计算触变特性参数精度高,不依赖于具体的函数形式,能有效克服传统计算方法的不足。