Facile modifications of polyimide via chloromethylation: II. Synthesis and characterization of thermocurable transparent polyimide having methylene acrylate side groups

From chloromethylated polyimide, a useful starting material for modification of aromatic polyimides, a thermocurable transparent polyimide having acrylate side groups was prepared. In the presence of 1,8‐diazabicyclo[5,4,0]undec‐7‐ene, chloromethylated polyimide was esterified with acrylic acid to synthesize poly(imide methylene acrylate). The polymer was soluble in organic solvent, which makes it possible to prepare a planar film by spin coating. The polymer film became insoluble after thermal treatment at 230 °C for 30 min. Optical transparency of the film at 400 nm (for 1 µm thickness) was higher than 98 % and not affected by further heating at 230 °C for 250 min. Adhesion properties measured by the ASTM D3359‐B method ranged from 4B to 5B. Preliminary results of planarization testing showed a high degree of planarization (DOP) value (>0.53). These properties demonstrate that poly(imide methylene acrylate) could be utilized as a thermocurable transparent material in fabricating display devices such as TFT‐LCD. Copyright © 2004 Society of Chemical Industry     

The Effect of Initial Inventories in a Two-Echelon System

A model in which jointly optimal stocks of material and finished products are to be chosen is reexamined. While it costs less to hold material, a certain percentage of the random demand not immediately satisfied by previously finished products is lost. We pay particular attention to the dependence of the optimal stocks on the initial ones, which assumes an interesting form. For example, if the stock of finished products is high but the combined stock is low, die quantity of material ordered depends on the stock of finished products.     

High-cycle fatigue characterization of titanium 5Al-2.5Sn alloy

High-cycle fatigue behaviour of titanium 5Al-2.5Sn alloy at room temperature has been studied. S-N curve characterization is performed at different stress ratios ranging from 0 to 0.9 on a subsized fatigue specimen. Both two-stress and three-stress level tests are conducted at different stress ratios to study the cumulative fatigue damage. Life prediction techniques of linear damage rule, double linear damage rule and damage curve approaches are applied, and results are compared with the experimental data. The agreement between prediction and experiment is found to be excellent.     

Specifying transformer winter and summer peak-load limits

This paper presents a methodology for specifying the winter and summer peak-load limits for substation transformers that carry a temperature-sensitive load, taking into account the random nature of load and ambient temperature as well as their correlation. With this methodology, we can easily and accurately specify the peak-load limits for each substation transformer once the historical ambient temperature and load data are available. Also, we can collectively specify the peak-load limits for the transformer of each cooling type (OA, OA/FA, or OA/FA/FA) in a geographic region based on the mean and standard deviation of ambient temperatures in that region. Such peak-load limits are useful for power system planning.     

Study of collective user behaviour in Twitter: a fuzzy approach

The study of collective user behaviours in social networking sites has become an increasing important topic in social media mining. Understanding such behaviours has its potential to extract actionable patterns that can be beneficial to develop effective marketing strategies, optimise user experiences and maximise website revenues. With the rapid development of micro-blogging, Twitter has become a richer source of intelligence that can be used to study collective user behaviour, due to its efficient and meaningful user-to-user interactions. However, the classical statistical methods have some drawbacks in bridging the gap between user-generated data and human analysts who mostly use linguistic terms to analyse data and model/summarise knowledge learned. To address this gap, this work proposes a new approach, which employs the mass assignment theory-based fuzzy association rules algorithm (MASS-FARM), for the first time, to extract useful interaction behaviour of Twitter users. The influential factors (including activity time, number of friends/followers and the number of tweets) are represented as fuzzy granules, and the associations amongst are studied by employing MASS-FARM. The collective user behaviours are analysed in the Reply category and the Non-Reply category, respectively. The applicability and usefulness of the proposed method are demonstrated via an empirical study on a collected Twitter data set. The derived results are also discussed and compared with existing works.     

浅谈工程项目管理的若干问题

随着我国社会经济的发展,人们对建筑的质量要求越来越高,建筑工程项目管理的作用也越来越大,其对保证建筑工程的实施和质量有着十分重要的意义。通过分析建筑项目管理工作的作用和具体内容,提出了改善和创新的方法和措施,以供相关单位借鉴和参考。     

高校广告学课程教学模式改革探讨

广告行业的繁荣,使得广告业成为当今社会炙手可热的行业之一,各地高校争相开办广告类专业或开设广告学课程.作者分析了目前高校广告学课程教学的现状,指出高校广告学课程教学中存在的不合理因素,并提出了改革建议,旨在适应市场经济发展的需要,创建具有特色的广告学课程教学新模式.     

信息化条件下任职士官计算机课程教学改革初探

针对任职士官计算机水平与部队信息化建设要求不相适应的现实问题,深入调查分析了某部队任职士官计算机水平的现状与实际需求,明确了士官任职教育计算机教学的目标,进而有针对性地提出了任职士官计算机课程教学改革的几点新思路,确保课程教学真正服务于部队,服务于实战。