激光熔覆高温自润滑覆层的裂纹成因与控制

分析了激光熔覆高温自润滑覆层裂纹的形成原因,讨论了裂纹的影响因素及控制措施。结果表明:在覆层拉应力的作用下,柱晶间界及低熔点液态润滑相富集区域极易产生结晶裂纹。在保证覆层功能的前提下,优化复合粉末的组分,抑制柱状枝晶的长大;采取梯度复合覆层工艺及熔覆工艺参数优化,改变覆层的组织结构,提高覆层的韧性;同时采取措施调整覆层应力状态,降低热应力作用,可以有效控制覆层的裂纹倾向。     

Effect of tetraphenylphenyl‐modified fumed silica on silicone rubber radiation resistance

Two kinds of treated fumed silica were prepared by treatment with either tetraphenylphenyltriethoxysilane (TPHTS) or both tetraphenylphenyltriethoxysilane and hexamethyldisilazane (TPHMTS), and were used as reinforcing filler for silicone rubber. The resistance to irradiation of the silicone rubber obtained was investigated by gamma ray of dose 500 kGy in air. The mechanical properties and the average molecular weight between crosslinking points (Mc) of the silicone rubber were determined before and after irradiation. The results show that the fumed silica treated by tetraphenylphenyltriethoxysilane (TPHPHS) can effectively improve the radiation resistance of silicone rubber while the fumed silica treated by both tetraphenylphenyltriethoxysilane and hexamethyldisilazane (MM^N) cannot only effectively improve the radiation resistance of silicone rubber but also has excellent reinforcing effect on silicone rubber. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

基于任务和角色的工作流权限控制研究与实现

结合国家电网ERP工作流项目的实际情况,分析了几种常见的访问控制模型在工作流权限控制中的不足,以及基于任务和角色的访问控制模型在实现权限动态管理方面的优势。并以项目模块工程付款流程为例,阐述了SAP客户化工作流的开发过程,以及基于任务和角色的访问控制在ERP工作流中的具体应用,最后介绍了本项目中工作流待办的展现方式。实践证明基于任务和角色的访问控制能够有效地实现权限的动态管理,较好地满足ERP工作流权限控制的需要。     

浅议新建搅拌站的选址与规划

本文主要从新建搅拌站的选址、厂区布局和零排放方面阐述基础建设规划对后期运营成本的影响。     

Dyeing method and properties of polymaleic acid dyes on cotton

A polymaleic acid dye based on poly(maleic anhydride) was synthesised and evaluated in the dyeing of cotton. A series of dyeing auxiliaries were examined, and results showed that a composite auxiliary agent consisting of 20 g/l of zinc nitrate and 30 g/l of dicyandiamide was the most effective when a conventional pad‐dry‐cure dyeing process was used. The fixation could reach 99% and the wash and dry rub fastness could reach grade 4 and grade 4–5 respectively. The decrease in tearing strength of the dyed cotton was between 17.8 and 32.1%.     

紧急停车系统（ESD）在清华气化炉中的应用

ESD简称为紧急停车系统,适用于高温、高压、易燃、易爆等连续性生产装置的安全保护系统。大唐呼伦贝尔化肥有限公司合成氨装置清华气化炉采用了康吉森公司的TRICON ESD系统。介绍了清华气化炉的工艺特点;简述了气化炉ESD系统的硬件构成和软件构成,阐明了工艺条件下紧急停车系统的联锁逻辑和操作要求。应用效果表明,采用ESD系统的2套清华炉实现了安全联锁的要求,保障了气化炉的安全稳定运行。     

利用相控阵雷达实现气象探测

短时临近气象预报需要天气雷达对天气目标进行定量测量,以便对天气现状以及发展趋势做出准确预判。相控阵雷达应用于气象探测,利用其多通道以及快速多变的波束扫描能力实现对天气目标的快速扫描,雷达系统设计采用实时在线标校的技术设计,能提高探测的可信度和气象产品的质量。文中在分析了气象探测原理的基础上,给出了微波相控阵雷达实现对气象目标定量探测的设计思路与技术要点。     

对高压并联电容器组中单台电容值在线监测的研究

对高压并联电容器在线监测系统进行研究,分析其原理和结构,研制出基于单台电容值监测的在线监测系统。该监测系统所有传感量都可以通过无线方式传输,不用现场布线,安装灵活方便。实际运行表明:对高压电容器组中每一台电容器的电容量的监测精度可以达到0.5级,能够实时的监测电容器的运行状态,实现对电容器故障的预警。     

What factors affect consumers’ dining sentiments and their ratings: Evidence from restaurant online review data

Online review data refers to customer opinions (e.g., text reviews, numerical ratings, and personal information) left on online retailing and review platforms. Here, we provide insight for food-related consumer sentiment study by using online review data. We present a case study using Yelp restaurant review data on what affects restaurant customers’ sentiment responses to dining out. In our case study, a sentiment-analysis method was used to extract and generate sentiment indices from 175,879 text-based Yelp restaurant reviews. We examined the relationships between our sentiment indices and ratings and showed that online review data can provide information about consumer dining sentiments. By using semi-automatic content analysis method, we first counted the most frequent 300 words in all text reviews and manually categorized those most frequent words into five topics: “food,” “service,” “expenditure,” “social,” and “miscellany”. We then computed the fraction of topic words in each category over the total topic words for each review. We found that (1) consumers used more positive sentiment words than negative sentiment words in their Yelp restaurant text reviews. (2) The proportion of positive sentiment words in reviews was positively related to ratings; the proportion of negative sentiment words in reviews was negatively related to ratings. (3) Relative to food, consumers used more sentiment words (both positive and negative) when they were discussing restaurant service. (4) Consumers used the least sentiment words when they were discussing social-related topics compared with the other topics (food, service and expenditure). (5) Consumers rated restaurant service higher than they rated food.     

准分子激光微加工技术结合模塑技术加工微流控芯片

利用准分子激光微加工技术与模塑技术相结合的方法制造微流控芯片。用准分子激光在玻璃基胶层上刻蚀出加工质量较高的微流控生物芯片形貌,通过电铸技术对微流控芯片进行复制,得到反向金属模具。用金属模具通过注塑成型技术用聚碳酸酯注塑出微流控芯片。系统研究了准分子激光的能量密度和工作台移动速度对胶层微通道加工质量的影响;测量并分析了激光刻蚀加工出的微流控芯片原型、电铸的反向金属模板和注塑成型后的微流控芯片的轮廓精度和表面粗糙度,上表面尺度偏差不大于2μm,底面粗糙度小于20 nm。对注塑出的微流控芯片和激光直写刻蚀的几何结构相同的微流控芯片的流动性能进行比较测试。在流速较小时,用激光微加工技术与模塑技术相结合的方法加工的微通道比准分子激光直写法所加工的微通道流动性能更好。