α-Al2O3纳米粉体的烧结行为

为了探讨在无压烧结过程中α-Al2O3纳米粉体的烧结行为和致密化过程,采用高分子网络凝胶法制备了α-Al2O3纳米粉体,经冷压成型后无压烧结了Al2O3陶瓷,结果表明:α-Al2O3晶种的加入明显降低了高分子网络凝胶法制备α-Al2O3粉体的相转变温度,在950℃较低温下就可获得α-Al2O3纳米粉体;生坯的相对密度随...     

基于交替迭代遗传算法的多级车间生产计划与调度的集成优化

为了提高多级生产系统的运作效率,研究了一类多周期的多级车间生产计划与调度的集成优化问题,该生产系统由一级混批Job-shop车间和一级混流装配车间串联而成.首先建立了该类集成优化问题的混合整数规划模型,该模型从上下游生产车间的需求关系出发,综合考虑上下游车间的物料平衡、设备负荷以及开工位置等约束条件,同时满足优化上下游生产线的费用目标.然后提出了一种交替式混合遗传协调优化算法求解该集成优化问题,其主要思想是给定计划用一种混合遗传算法求调度,反过来给定已求调度用另一种混合遗传算法求取新计划,如此不断交替使用2种混合遗传算法实现计划与调度的同时优化.仿真结果证明了该方法的可行性和有效性.     

A content-based parallel image retrieval system on cluster architectures

We propose a content-based parallel image retrieval system to achieve high responding ability. Our system is developed on cluster architectures. It has several retrieval servers to supply the service of content based image retrieval. It adopts the Browser/Server (B S) mode. The users could visit our system though web pages. It uses the symmetrical color-spatial features (SCTSF) to represent tile content of an image. The SUSF is effective and efficient for image matching because it is independent of image distortion such as rotation and flip as well as it increases the matching accuracy. The SCSF was organized by M tree. which could speedup the searching procedure. Our experiments show that the image matching is quickly and efficiently with the use of SCSF. And with the support of several retrieval servers, the system could respond to many users at mean time.     

Web-Based Information Systems and Applications： A Survey

World Wide Web (WWW) has given rise to phenomenal growth in Web information systems and applications. And the Internet transcends national and geographical boundaries and has brought about unprecedented opportunities for software deployment to satisfy the application needs of all walks of life. Since the Web provides cross-platform universal access to resources for the massive user population, even greater demand is proposed to manage data and information effectively.     

A novel fabrication of meso-porous silica film by sol-gol of TEOS

A homogeneous crack-free nano- or meso-porous silica films on silicon was fabricated by colloidal silica sol derived by hydrolyzing tetraethyl orthosilicate (TEOS) catalyzing with (C4H9)4N+OH- in water medium. The solution with ratio of H2O/TEOS> or =15, R4N+ and glycerol as templates, combining with the hydrolyzed intermediate, controlled the silica aggregating; the templated silica film with heterostructure was developed into homogeneous nano-porous then meso-porous silica films after being annealed from 750 degrees C to 850 degrees C; the formation mechanism of the porous silica films was discussed; morphologies of the silica films were characterized. The refractive indexes of the porous silica films were 1.256-1.458, the thermal conductivity < 0.7 W/m/K. The fabricating procedure and the sequence had not been reported before.     

X70管线钢韧-脆断裂转变研究

在不同温度下研究了X70管线钢动态断裂韧度K1d,J1d和止裂韧度K1a以及夏氏V型缺口冲击韧度(CVN)。研究表明,断裂韧度受温度和加载速率的影响较为强烈;当温度由213K向193K逐渐降低而加载速率逐渐从0.01向1000mm/s增大时,断裂韧度逐渐减小;在恒温下,增大加载速率可以诱发韧-脆断裂转变,应引起足够重视。     

Gas and pressure effects on the synthesis of amorphous carbon nanotubes

The effects nf gas. pressure and temperature on the production of amorphous carbon nanotubes were investigated using an are discharging furnace at controlled temperature. Co/Ni alloy powder was used as catalyst. The discharge current was 80 A and voltage was 32 V The optimal parameters were obtained: 600℃ temperature, hydrogen gas and 500 torr pressure. The productivity and purity of amorphous carbon nanotubes are 6.5 gram per hour and 80%, respectively. The diameter of the amorphous carbon nanotubes is about 7—20 nm.     

有限深度液体中气泡的破碎条件

针对球形气泡在有限深度液体内的运动过程，建立了气泡壁初始运动导致气泡破碎的数理模型．该模型综合考虑了流体黏性力、气泡壁初始速度、有限液面高度等因素，是传统R-P方程的一种改进．研究发现气泡临界破碎条件与液体高度、气泡壁初始速度等因素密切相关，随着液体深度的增大，气泡更容易破碎．当液体深度大于气泡半径的100倍以上时，液体深度对气泡破碎临界条件几乎无影响，此时可以近似认为气泡位于无穷深液体中．当气泡壁初始速度为0时，气泡不容易破碎；当气泡具有初始收缩速度时，气泡最容易破碎．通过分析得到了气泡壁初始速度为0时的临界破碎准则预测式，并与其他文献的结果进行了比较．     

Family genetic algorithms based on gene exchange and its application

1. INTRODUCTION Genetic algorithms (GA) are a search techniques bas-ed on mechanics of nature selection and were initiallyproposed by Holland[1]. GA have already beensuccessfully applied in many diverse areas, such asfunction optimization, the traveling salesman proble-ms, multiobje-ctive optimization problems, schedulingneural network design, system identification, visioncontrol and machine learning. A detailed review ofthese applications is provided in Refs. [2] and [3]. The strength …     

ENERGY-EFFICIENT SENSING COVERAGE AND COMMUNICATION FOR WIRELESS SENSOR NETWORKS

Wireless sensor networks have a wide range of applications. Sensing coverage and communication coverage are two fundamental quality of service. In this paper, we present our work on energy efficient sensing coverage and communication. We design several schemes for sensing coverage subject to different requirements and constraints respectively. We also propose a broadcasting communication protocol with high energy efficiency and low latency for large scale sensor networks based on the Small World network theory. Simulation and experiment results show that our schemes and protocol have good performance.