国产MB-86催化剂使用情况分析

抚顺引进的５００００ｔ／ｙ丙烯腈装置要改造到７００００ｔ／ｙ的生产能力，其中更换国产催化剂ＭＢ－８６是较为关键的一步，文章对此进行了总结与分析。     

卫星下行链路计算及接收天线增益的测量

１９９９年４月份 ,辽宁省广播电视厅对辽宁省广播电视“村村通”工程所需卫星接收设备和有线广播电视设备的采购进行国内邀请招标 ,我站承担了对投标公司的天线及高频头进行检测的任务。天线系统检测有多项指标要求。这里我只就接收天线的增益这项指标 ,谈谈我们的计算及测量方法。天线因集中辐射而获得的功率增加 ,称为天线增益。微波天线的增益可表示为 :Ｇ＝４πＡｔＺ/λ２式中 :Ａｔ———天线的开口面积 ;λ———接收波长 ;Ｚ———天线开口效率。对于前馈抛物面天线来说 ,开口效率的典型数值为０ .５５。辐射波长与辐射频率成反比 …     

扁平流线型箱梁涡激振动雷诺数效应研究

风洞试验作为研究涡激振动的重要手段,由于其本身条件的限制,可能存在雷诺数效应问题,造成试验值和实际值的偏差.为了研究扁平流线型箱梁涡激振动的雷诺数效应,选取某大跨度斜拉桥的扁平流线型箱梁作为研究对象,利用风洞测振试验,通过调节模型系统自振频率,实现不同雷诺数下的涡激振动,研究扁平流线型箱梁的涡激振动特性及其雷诺数效应;...     

Effect of thermotropic liquid crystalline poly(ether ketone)arylates on the processibility and properties of poly(ether ether ketone)s fibers

A series of composite fibers based on poly(ether ether ketone)s (PEEK) and a thermotropic liquid crystalline poly(ether ketone)arylates (PEKAR) have been prepared by melt spinning. The structure, compatibility, and properties of these composite fibers were investigated in detail by rheological measurements, differential scanning calorimetry, thermogravimetric analysis, wide‐angle X‐ray diffraction, scanning electron microscopy, orientation degree test, and mechanical properties test. The results showed that the addition of PEKAR could reduce the apparent melt viscosity of the blends obviously, which is beneficial in improving the processibility of PEEK at a relatively low temperature. After adding 1 wt % PEKAR to PEEK, the tensile strength of the post‐treatment fiber improved by 8.8%, whereas the crystallinity of the as‐spun fiber increased from 21.76% to 31.51%, and the orientation degree also increased with the addition of PEKAR. The result of morphology research suggested that PEKAR had a good compatibility with PEEK resin. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40595.     

Automated post scoring: evaluating posts with topics and quoted posts in online forum

Online forumpost evaluationis an effective way for instructors to assess students’ knowledge understanding and writing mechanics. Manually evaluating massive posts costs a lot of time. Automatically grading online posts could significantly alleviate instructors’ burden. Similar text assessment tasks like Automated Text Scoring evaluate the writing quality of independent texts or relevance between text and prompt. And Automatic Short Answer Grading measures the semantic matching of short answers according to given problems and correct answers. Different from existing tasks, we propose a novel task, Automated Post Scoring (APS), which grades all online discussion posts in each thread of each student with given topics and quoted posts. APS evaluates not only the writing quality of posts automatically but also the relevance to topics. To measure the relevance, we model the semantic consistency between posts and topics. Supporting arguments are also extracted from quoted posts to enhance posts evaluation. Specifically, we propose a mixture model including a hierarchical text model to measure the writing quality, a semantic matching model to model topic relevance, and a semantic representation model to integrate quoted posts. We also construct a new dataset called Online Discussion Dataset containing 2,542 online posts from 694 students of a social science course. The proposed models are evaluated on the dataset with correlation and residual based evaluation metrics. Compared with measuring posts alone, experimental results demonstrate that incorporating topics and quoted posts could improve the performance of APS by a large margin, more than 9 percent on QWK.

     

热致性液晶聚芳酯的相对分子质量控制与性能

用对苯二甲酸(TPA)作为相对分子质量调节剂,将6-乙酰氧基-2-萘甲酸和对乙酰氧基苯甲酸通过熔融酯交换和固相缩聚两步法,合成了数均相对分子质量约为5619~12264的热致液晶聚芳酯(PAT)。采用傅里叶变换红外光谱、核磁共振波谱仪、偏光显微镜、热失重分析和差示扫描量热分析等手段对单体和聚合物进行了结构与性能表征。结果表明,所制备的聚合物结构与实验设计相符,其热稳定性随着聚合物相对分子质量的增加而提高,在高温下保持向列型液晶相,因此在高温下可以与其他聚合物复合加工。当聚合物发生固相缩聚以后,聚合物的相对分子质量变大,结晶性能变好,热稳定性也明显提高。     

电动四通蝶阀在某电厂中的应用

电动四通蝶阀是一种流体换向阀门。介绍了电动四通蝶阀在某电厂改扩建工程中的应用,其应用简化了阀门设置,方便了操作,易于实现正常供水、备用供水、模糊供水等工况的切换。     

新的网络威胁无处不在

网络安全的焦点已经转变 网络攻击终日无止,安全威胁无 处不在,让机关、企业和个人头痛不已。 据网络安全紧急响应小组提供的数据显 示,2004年已知的系统漏洞数量较2000 年爆涨三倍,冰山之下还有差不多一半 数量的未知攻击正不断向人们伸出黑恶 之手,而这些未知攻击更令人心存余 悸、不知所措。     

Glass Transition Temperature in Microcellular Foaming Process with Supercritical Carbon Dioxide: A Review

In microcellular foaming process, the glass transition temperature (T_g) of polymer determines foaming temperature and has an effect on the other physical properties of polymer. In thisstudy, an evaluation of the current state of understanding for T_g was reviewed. Inaddition, we focused on the establishment and advancement of three main widely-used models that predict T_g (i.e. Chow model, Cha-Yoon model and Condo - Sanchez model). The comparisons of the three T_g-prediction models, with attention being given to their ownadvantages, disadvantages and scopes of application provide a reference for the further study.     

论包装设计专业人才的情商培养

对包装设计专业人才情商培养的重要性和现状作了客观分析,指明了包装设计专业人才的情商培养目标,即要培养与现代包装设计相适应的人本精神、创新精神、奉献精神、合作精神以及平等精神和宽容心态。