3G网络规划中自动基站分布算法的研究

自动基站分布问题属于组合优化中的NP完备问题,为此针对3G网络规划,在遗传算法的基础上,采用DCMOGADES算法的思想提出了一种新的自动基站分布算法。算法以容量、覆盖和成本作为目标,采用基站位置、天线高度和发射功率的三维向量编码方式,考虑了实际问题中的业务密度区域问题,对DCMOGADES算法进行改进并做出仿真。仿真结果表明,该算法能快速找到Pareto最优解。     

对农村教师借调现象的思考——以山东省某市为例

近几年来,乡镇教师借调到城市学校的现象较为普遍,使教育资源配置不合理的情况进一步恶化,带来了一些社会问题.根据对山东省某市教师借调现状的调查和原因分析,提出了从根本上改变农村贫穷落后状况,各级政府应转变观念,重视教育;加强教师自身修养,提高综合素质;深化人事制度改革,加强教师队伍建设等设想,以彻底改变这种教师借调现象.     

Code talk: Student discourse and participation with networked handhelds

This study explores the potential of networked handheld computers to support collaborative problem solving in small groups. Drawing on data from a middle school mathematics classroom equipped with a wireless handheld network, I argue that the sharing of mathematical objects through interactive devices broadens the ‘bandwidth’ of classroom collaboration, expanding the range of participatory forms through which students might contribute to the work of a group and enhance their own learning. The analysis focuses on the participation strategies of those students in two focus groups who were most able to demonstrate posttest score gains from relatively low scores on a pretest. In particular, the device network provided those students with a set of collective, dynamic objects through which they supplemented and coordinated discursive forms of participation in the joint work of their respective groups.     

水电站机组监控系统中上位机与下位机的通信实现

介绍了在水电站机组监控系统中,如何利用VB来实现上位机与三菱FX系列PLC的通信,上位机与三菱FX系列PLC之间采用计算机链接通信方式.并介绍了水电站机组监控系统的通信方式、通信规约以及所采取的提高通信可靠性的措施.经水电站实际运行证明,该通信方式运行稳定、可靠.     

服装中小企业与中国服装业的发展

服装产业和服装市场的特点决定了中小企业在服装业中的主导地位。中小型服装企业是决定中国服装业综合竞争力的主要力量。发挥服装中小企业的潜力,构筑企业的核心能力,进而聚合为中国服装产业的国际竞争力的要点是:柔性的生产体系、柔性的产业组织、柔性的产业战略理念、柔性的经营方式、柔性的生产技术、柔性的产品系列和柔性的市场环境。     

基于三层架构的电视台广告管理信息系统

介绍了应用服务器三层架构的优势，详细给出了Oracle Forms Server在Web上运行应用程序的工作机制，并结合实际并发经验，论述了三层架构的电视台广告管理系统的设计思想和功能。     

万能嵌线架的设计

本文主要阐述了万能嵌线架的设计思路,工作原理设计方案及使用方法,旨在提高大功率中小型电机嵌线的工艺水平,降低工人劳动强度,提高产品质量。     

石化企业高硫石油焦利用途径探讨

介绍了高硫石油焦作锅炉燃料、气化原料和水泥窑燃料等几种利用方法,并进行了技术经济比较。提出当石化企业新增用气和用电负荷较大时,建设循环流化床热电站燃用高硫石油焦应是首选方案,否则高硫焦以外销为好。石油焦气化技术如果能结合供汽、供电和化工物料联产进行设计,可增大气化规模,充分利用规模效益,这样做尽管投资较大,还是有竞争力的,而且该方案的环保效果较好。石化企业在经济条件许可的情况下,可考虑选用高硫石油焦气化方案,如企业自产的高硫石油焦不够,可将几家企业所产的高硫石油焦集中使用,或高硫石油焦与煤混用。     

农田水利建设的新思路新方法新突破

农田水利建设是农业基础设施建设的中心环节。建设现代新型农田水利要有新思路、新方法、新突破．概括为围绕一条主线、坚持五项原则、健全五大体系、实现五个目标、落实八项措施，形成综合实力强大、宏观调控有力、科技含量较高、管理服务高效、综合效益显著、发展后劲充足的现代新型农田水利事业．     

SMALL CRACK GROWTH AND FATIGUE LIFE PREDICTIONS FOR HIGH-STRENGTH ALUMINIUM ALLOYS: PART I—EXPERIMENTAL AND FRACTURE MECHANICS ANALYSIS

The small crack effect was investigated in two high-strength aluminium alloys: 7075-T6 bare and LC9cs clad alloy. Both experimental and analytical investigations were conducted to study crack initiation and growth of small cracks. In the experimental program, fatigue tests, small crack and large crack tests were conducted under constant amplitude and Mini-TWIST spectrum loading conditions. A pronounced small crack effect was observed in both materials, especially for the negative stress ratios. For all loading conditions, most of the fatigue life of the SENT specimens was shown to be crack propagation from initial material defects or from the cladding layer. In the analysis program, three-dimensional finite element and weight function methods were used to determine stress intensity factors and to develop SIF equations for surface and corner cracks at the notch in the SENT specimens. A plasticity-induced crack-closure model was used to correlate small and large crack data, and to make fatigue life predictions. Predicted crack-growth rates and fatigue lives agreed well with experiments. A total fatigue life prediction method for the aluminium alloys was developed and demonstrated using the crack-closure model.