AZ80镁合金管材热挤压工艺及组织性能研究

选用不同的工艺参数对变形镁合金AZ80进行管材热挤压工艺实验研究;对挤压前后材料组织与力学性能的变化进行分析。研究结果表明：热挤压可以显著细化AZ80镁合金的晶粒,而且随着挤压比的增加,晶粒变得更加细小;增大挤压比也可以提高AZ80镁合金的抗拉强度和屈服强度。挤压比为18.2,坯料温度为390℃,模具预热温度360℃,凹模的半模角为60°～70°,可得到均匀的合金组织和良好的力学性能.     

高等院校内部财务控制方式的研究

高校财务管理是高校各项管理的重要组成部分。针对我国高等院校目前财务管理中财务控制面临的主要问题,从建立全面的内部预算控制管理系统、建立费用绩效控制核算体系、建立财务风险防范体制等三个方面入手,指出建立高校全方位内部财务控制的方向,使高校能在完善现有财务管理工作的基础上,把有限的学校资金合理有效地分配到教学、科研、学校建设发展等各个方面,让高校的内部财务控制真正能适应高校新的发展环境变化及高校自身财务管理的实际要求。     

Z源直流变换器电感电流断续工作模式分析

Z源变换器具有新型的拓扑结构,在输入直流电源和输出变换器之间采用独特的Z源网络进行连接,以获得更好的升/降压效果.在电感电流断续条件下,对Z源直流变换器的工作状态进行了详细分析,利用稳态条件下电感平均电流为零的条件推导出Z源直流变换器的升压比,进一步分析出临界电感的计算公式,并通过仿真验证了理论分析的正确性.     

Synthesis of Li2Fe0.9Mn0.1SiO4/C composites using glucose as carbon source

Li2Fe0.9Mn0.1SiO4/C composites were synthesized by using glucose as carbon source. The samples were characterized by X-ray diffractometry (XRD), scanning electron microscopy (SEM) and electrochemical measurements. All Li2Fe0.9Mn0.1SiO4/C composites are of the similar crystal structure. With increasing the carbon content in the range of 5%-20% (mass fraction), the diffraction peaks in XRD patterns broaden and the particle sizes and the tap density of samples decrease. The Li2Fe0.9Mn0.1SiO4/C composites with carbon content of 14.12% show excellent the capacity retention remains 92.2% after 30 cycles.     

Prediction-based energy-efficient target tracking protocol in wireless sensor networks

A prediction based energy-efficient target tracking protocol in wireless sensor networks (PET) was proposed for tracking a mobile target in terms of sensing and communication energy consumption. In order to maximize the lifetime of a wireless sensor network (WSN), the volume of messages and the time for neighbor discovery operations were minimized. The target was followed in a special region known as a face obtained by planarization technique in face-aware routing. An election process was conducted to choose a minimal number of appropriate sensors that are the nearest to the target and a wakeup strategy was proposed to wakeup the appropriate sensors in advance to track the target. In addition, a tracking algorithm to track a target step by step was introduced. Performance analysis and simulation results show that the proposed protocol efficiently tracks a target in WSNs and outperforms some existing protocols of target tracking with energy saving under certain ideal situations.     

Modeling of metadynamic recrystallization kinetics after hot deformation of low-alloy steel Q345B

Based on the steady-state strain measured by single-pass hot compression tests, the method by a double-pass hot compression testing was developed to measure the metadynamic-recrystallization kinetics. The metadynamic recrystallization behavior of low-alloy steel Q345B during hot compression deformation was investigated in the temperature range of 1 000–1 100 °C, the strain rate range of 0.01–0.10 s⁻¹ and the interpass time range of 0.5–50 s on a Gleeble-3500 thermo-simulation machine. The results show that metadynamic recrystallization during the interpass time can be observed. As the deformation temperature and strain rate increase, softening caused by metadynamic recrystallization is obvious. According to the data of thermo-simulation, the metadynamic recrystallization activation energy is obtained to be Q _md=100.674 kJ/mol and metadynamic recrystallization kinetics model is set up. Finally, the error analysis of metadynamic recrystallization kinetics model proves that the model has high accuracy (correlation coefficient R=0.988 6).     

一种新的模糊自适应模拟退火遗传算法在配电网重构中的应用

本文对配电网的重构问题进行了研究,提出了结合实际的配电网重构目标函数,并将遗传算法引入其中,用来解决这个复杂的,多目标,多约束的组合优化问题。针对遗传算法收敛速度慢、容易"早熟"等缺点,结合模糊推理、模拟退火算法和自适应机制,采用一种改进的遗传算法——模糊自适应模拟退火遗传算法(FASAGA),实例分析表明,该算法比标准的遗传算法(SGA)具有更快的收敛速度和寻优效果。     

基于J2ME和J2EE的移动学习平台研究与设计

随着移动设备性能的不断提高,在移动设备上的应用也越来越广泛,移动学习正是随着移动信息技术发展而产生的一种新兴的学习方式。本文提出了基于J2ME和J2EE技术的移动学习平台的设计方案,这个平台采用J2ME技术作为客户端的实现技术以屏蔽移动设备间的巨大差异性,采用J2EE技术作为服务器端的实现技术以提供高效稳定的服务。     

开发计划在面向市场和定制中各自侧重概述

现在的软件产业中主要是面向市场开发和定制开发这两种形式．本文通过分析在面向市场软件开发和定制软件开发中影响成功的元素和讨论项目计划与项目结果的关系来总结在做软件项目计划时各自需要重视和强调的部分。     

CFRP加固大偏压RC柱二次受力时的机理分析

柱外部粘贴碳纤维布(Carbon fiber reinforced polymer,以下简称CFRP)加固,是一种安全、经济和快捷的加固方法,当今已经广泛地应用于工程中.钢筋混凝土(Reinforced concrete,以下简称RC)柱加固时一般难以完全卸载,因此加固后的RC柱存在明显的二次受力问题.比较了一次受力与二次受力的区别,针对CFRP加固的大偏心受压柱,推导了1种破坏模式下的承载力计算公式.分析了纵、横向加固CFRP后对柱受压侧混凝土强度的提高作用,并且提出界限状态下纵向CFRP界限加固量计算公式.