天津医科大学图书馆中文专业图书资源利用效率统计分析

以天津医科大学图书馆UNICORN集成管理系统的各项记录为数据源,挖掘整合了2004—2013年中文专业图书有关数据,从综合性、动态性角度,统计分析了图书购置数量、图书借阅数量及购书经费分布等有关数据,旨在为提高图书馆管理水平提供参考依据。     

Microstructure,mechanical properties and wear resistance of an Al–Mg–Si alloy produced by equal channel angular pressing

Microstructure, mechanical properties and wear resistance in an ultrafine-grained Al–Mg–Si alloy fabricated utilizing a combination of equal channel angular pressing (ECAP) and dynamic aging were investigated in this paper. The results indicated that the grain size of the ECAP alloy was significantly refined, i.e., to ~239 nm after three ECAP passes. Meanwhile, the yield and tensile strength of the ECAPed material reached 340 MPa and 445 MPa, respectively, while maintaining a significant uniform elongation of 14%. Wear resistance results demonstrated that the wear rate, wear depth and width of the ECAPed material decreased in comparison with the solution-treated (SST) and peak-aged (T6) conditions under a load range of 5–25 N. The adhesive wear that occurs in the undeformed specimens at 10 N does not appear in the ECAPed specimen at the same load, indicating that the ECAPed specimen delay the appearance of more serious wear mechanisms under certain loads. The cooperative interaction of high density nano-scale β" precipitates and dislocations resulted in a combination of super-high strength and good work hardening ability which suppressed the extension of cracks between the friction layer and the plastic deformation zone. As a consequence, the combination of ECAP and dynamic aging brings a significant improvement for antifriction performance of the 6061 aluminum alloy.     

非锚固式大型立式热质储罐强度分析

针对大型储罐在多种载荷作用下易发生强度破坏的问题，以某热质储罐为研究对象，利用有限元法分析热质储罐在自重、内压、液柱静压力、风载荷、地震载荷、雪载荷以及温度载荷作用下的应力强度以及变形，模拟大角焊缝区域翘曲情况，并依照JB4732—1995进行强度评定，为此类大型立式储罐的设计提供参考。     

考虑单元互测的测试性指标分配方法

测试性分配是将系统级测试性指标按照一定规则分配给各组成单元的过程。针对现有主流测试性分配方法未考虑单元之间的互测情形,导致分配结果不合理,尤其是部分单元分配指标虚高,难以实现或代价过高等问题,提出了在综合考虑单元故障率、故障危害度等多重影响因素基础上,进一步考虑单元互测因素的测试性指标分配方法。首先实施考虑多重影响因素的指标初次分配;然后基于单元测试性初步设计结果,实施测试性建模与分析,得到单元自检故障率与他检故障率;再利用这两个数据以及初次分配结果构造分配函数实施再次分配,进而得到最终的分配结果;最后应用该方法进行仿真和实例运算,证明了该方法的有效性和先进性。     

Abrupt climate change：Debate or action

Global abrupt climate changes have been documented by various climate records, including ice cores, ocean sediment cores, lake sediment cores, cave deposits, loess deposits and pollen records. The climate system prefers to be in one of two stable states, i.e. interstadial or stadial conditions, but not in between. The transition between two states has an abrupt character. Abrupt climate changes are, in general, synchronous in the northern hemisphere and tropical regions. The timescale for abrupt climate changes can be as short as a decade. As the impacts may be potentially serious, we need to take actions such as reducing CO2 emissions to the atmosphere.     

基于BP网络的反馈控制器设计

针对常规反馈控制器参数在对象时变情况下难以获得最优的问题，利用BP神经网络构成系统反馈控制器，通过自适应学习速率在线调整网络权值以逼近对象的逆动态模型，并利用Lyapunov方法给出了该算法的收敛的条件。将算法应用于循环水温度控制系统表明：该控制器对模型参数不依赖，能有效地适应控制对象参数的变化，系统具有较强的鲁棒性。     

图析宁波电视收视格局

文章对宁波的电视收视总体格局、晚间时段各电视频道的竞争态势,以及电视剧在宁波的收视情况作了由总及分的探讨和分析,将数据做成图表的形式形象、科学地解构了宁波电视的收视格局,对了解宁波电视收视情况和促进各台竞争提供了实际的参考价值.     

矩形型钢弯曲回弹曲率半径r值的确定

文章在分析矩形型钢弯曲变形过程及应力与应变等方面的关系的基础上，推导出工件曲率半径与工件回弹后曲率半径之间的关系，从而确定了凸模半径。     

干燥工艺对稻谷发芽率影响的研究

利用薄层干燥试验台，采用二次回归正交组合设计试验对辽宁省稻谷主要品种942进行研究。分析了热风温度、表现风速、初始水分、干燥时间对稻谷发芽率损失影响的规律，建立了稻谷发芽率损失回归方程，在干燥时应采用低温干燥，以保证其发芽率。利用贡献率法确定各因素在二次非线性模型中的主次关系为热风温度、初始水分、表现风速、干燥时间，为进行辽宁省稻谷深床干燥研究提供了理论依据。     

运用TQC方法提高活塞质量

在生产中通过运用ＴＱＣ方法和ＰＤＣＡ循环，降低了活塞热加工毛坯的废品率，从而提高了活塞质量，取得了较好的经济效益。