C-C INTERACTION ENERGY IN Fe-C ALLOYS

本文提出一种新方法,从现有活度实验数据求得Fe-C合金奥氏体和铁素体中C-C交互作用能,碳的偏摩尔焓和偏摩尔非配置熵.将这些数据用于计算Fe-C相图,平衡部分结果与实测相图十分符合.同过去的方法相比较,本文方法能从分散、有限的活度实验数据中得到更合理的结果.然而分析表明,迄今碳在铁素体中活度数据仍欠精确,尚难依据它来确定具有明确物理意义的铁素体中C-C交互作用能数值。     

Sampling strategy design for dimensional measurement of geometric features using coordinate measuring machine

Dimensional measurement using a coordinate measuring machine (CMM) has been commonly adapted in advanced manufacturing environments to ensure that manufacturing products have high quality and reliability. To conduct dimensional inspection effectively in a computer-integrated manufacturing (CIM) environment, there is an urgent need to derive a sampling strategy which can be used to specify a set of measuring points that lead to accurate sampling while minimizing the sampling time and cost. Owing to the variations in characteristics of geometric features and manufacturing processes, different feature surfaces on a workpiece usually have different variations in their dimensional accuracy and surface finish. The variations may differ considerably from one surface to another, even though those surfaces may share the same feature. Therefore, the variation in dimensional accuracy and surface finish should be considered in determining the proper sampling size for each geometric feature generated by various processes with different production parameters. In this paper, a feature-based methodology which integrates the Hammersley sequence and a stratified sampling method are developed to derive the sampling strategy for various geometric features which have specified measuring points. Case studies are used to compare the effectiveness of Hammersley sequence sampling, uniform (systematic) sampling and random sampling. The results show that the derived sampling strategy based on the Hammersley sequence leads to a nearly quadratic reduction in the number of samples compared with the uniform sampling method, and hence units of time and cost, while maintaining the same level of accuracy. The derived sampling strategy also shows a better performance when compared with the random sampling method.     

MathCAD软件对塑料发泡振动的模拟

气泡膨胀过程中产生的高频振动已达到超声波范围,对聚合物中纳米粒子的分散具有很好的作用。利用MathCAD模拟了气泡振动影响因素,分析了气泡内外压差、高聚物熔体的表面张力、应力松弛时间等因素对气泡振动的影响。通过分析,对气泡振动的工艺条件提出一些参考。     

燃料电池用Cu-Ce(La)Ox变换催化剂

对采用共沉淀法制备的Cu-Ce(La)O_x高温变换催化剂进行了研究，包括中和pH值、中和温度、焙烧温度和方式以及CuO、CeO₂和LaO_x含量对催化剂性能的影响。5%CuO-CeO₂-La(10%)O_x高温变换催化剂的最佳制备工艺条件为：pH＝11，中和温度54 ℃，400 ℃焙烧4 h。催化剂的最佳质量分数配比是：CuO 为20%，CeO₂ 为70%，LaO_x 为10%。XRD晶相分析表明，5%Cu-Ce-La(10%)O_x催化剂中除了主相CeO₂以外，还出现了Cu与La形成的钙钛矿型复合氧化物CuLaO₂，且CuLaO₂高度均匀地分散在主相CeO_x中；还原态中除了CeO₂、CuLaO₂外，还出现了Cu单质。因此，这类催化剂的活性中心不可能是简单的CuLaO₂或Cu，这使得催化剂无论氧化态还是还原态都具有基本相同的活性。催化剂的活性位形态结构尚需做进一步研究。     

小型图书管理系统的设计和实现

图书管理系统作为现代社会高校日常事务中不可或缺的一个IT系统,拥有悠久的历史传承。从其功能上看,它将图书工作人员从繁琐、杂乱的图书管理信息中解救出来,也使得读者能够更快捷全面的了解图书信息。作为软降工程的一个项目,小型图书管理系统实现了计算机的管理自动化。此系统,用C#开发前端界面和后台业务,用SQL作为数据库来存放读书信息。实现了信息管理、借还操作、图书排列及信息查询等多个必须功能。从结果上看前期工作已基本上满足日常图书管理工作的基本需求。     

多层结构隐身涂层附着力测试探讨

优选了多层结构隐身涂层附着力的测定方法,研究了多层结构隐身涂层在自然环境中附着力的变化规律,指出了树脂耐低温和耐温变的重要性。     

局部表面改性紫铜方柱阵列池沸腾传热特性和机理

以局部表面改性的紫铜直方柱和梯度方柱阵列为研究对象，实验研究了表面润湿性、表面形貌和表面活性剂对池沸腾换热性能和气泡生长特性的影响。实验工质为去离子水，浓度分别为100、200、400、800 mg·L^-1的异丙醇溶液和正庚醇溶液。实验结果表明：方柱阵列表面镀银之后润湿性变差，表面产生的气泡数量减少。向去离子水中添加异丙醇或正庚醇后，在热通量为66.1～202 kW·m^-2时，气泡脱离直径变小、数目减少，而当热通量增至413 kW·m^-2时，活性剂能够有效阻碍气泡合并，故池沸腾传热系数随着浓度增加先减小后增大。上下层宽分别0.5 mm和1 mm、间距为2 mm的梯度方柱阵列结构有助于气泡的合并，但由于促进了固体表面气膜的形成，从而降低了沸腾换热性能。     

发挥大学生在思想政治理论课教学中的主体作用

近年来,着力培养和发展大学生的主体意识和主动精神逐渐成为人们的共识.目前,高校思想政治理论课教学未能充分发挥大学生的主体作用,存在教学方法陈旧,教学环节单一,学生被动接受知识,无法做到理论联系实际等弊端.教师要转变教育教学观念,创新教育教学方法,从而真正发挥大学生在思想政治理论课教学中的主体作用.     

Prevention and forecasting of rock burst hazards in coal mines

Rock bursts signify extreme behavior in coal mine strata and severely threaten the safety of the lives of miners, as well as the effectiveness and productivity of miners. In our study, an elastic-plastic-brittle model for the deformation and failure of coal/rock was established through theoretical analyses, laboratory experiments and field testing, simulation and other means, which perfectly predict sudden and delayed rock bursts. Based on electromagnetic emission (EME), acoustic emission (AE) and microseism (MS) effects in the process from deformation until impact rupture of coal-rock combination samples, a multi-parameter identification of premonitory technology was formed, largely depending on these three forms of emission. Thus a system of classification for forecasting rock bursts in space and time was established. We have presented the intensity weakening theory for rock bursts and a strong-soft-strong (3S) structural model for controlling the impact on rock surrounding roadways, with the objective of laying a theoretical foundation and establishing references for parameters for the weakening control of rock bursts. For the purpose of prevention, key technical parameters of directional hydraulic fracturing are revealed. Based on these results, as well as those from deep-hole controlled blasting in coal seams and rock, integrated control techniques were established and anti-impact hydraulic props, suitable for roadways subject to hazards from rockbursts have also been developed. These technologies have been widely used in most coal mines in China, subject to these hazards and have achieved remarkable economic and social benefits.     

多孔介质微波加热厚度的确定

简述了微波加热的机理，以湿木材为研究对象，通过理论计算确定了微波在木材中的穿透深度。计算表明：随着木材含水率和微波工作频率的增加，微波在木材中的穿透深度减小；当用频率为915MHz和2450MHz的微波加热或干燥具有高含水率的多孔介质时，多孔介质的最大厚度应分别控制在16cm和6cm以内。