Stability of switched positive nonlinear systems

This paper considers the stability problem for a class of switched positive nonlinear systems (SPNSs), which includes switched positive linear systems as a special case. We derive a necessary and sufficient condition for stability of continuous‐time SPNSs defined by homogeneous and cooperative vector fields under average dwell time switching. A corresponding necessary and sufficient condition is also given for stability of discrete‐time SPNSs defined by homogeneous and order‐preserving vector fields under average dwell time switching. The stability results for switched positive linear systems, which have been studied in the literature, can be easily obtained. We also extend the results to general switched linear systems. Finally, a numerical example is provided to illustrate the effectiveness of our results. Copyright © 2015 John Wiley & Sons, Ltd.     

Sintering‐induced delamination of thermal barrier coatings by gradient thermal cyclic test

Lifetime is crucial to the application of advanced thermal barrier coatings (TBCs), and proper lifetime evaluation methods should be developed to predict the service lifetime of TBCs precisely and efficiently. In this study, plasma‐sprayed YSZ TBCs were subjected to gradient thermal cyclic tests under different surface temperatures, with the aim of elucidating the correlation between the coating surface temperature and the thermal cyclic lifetime. Results showed that the thermal cyclic lifetime of TBCs decreased with the increasing of surface temperatures. However, the failure modes of these TBCs subjected to thermal cyclic tests were irrespective of different surface/BC temperatures, that is, sintering‐induced delamination of the top coat. The thickness of thermally grown oxide (TGO) was significantly less than the critical TGO thickness to result in the failure of TBCs through the delamination of top coat. There was no phase transformation of the top coat after failure. In contrast, in the case concerning the top coat surface of the failure specimens, the elastic modulus and microhardness increased to a comparable level due to sintering despite of the various thermal cyclic conditions. Consequently, it is conclusive that the failure of TBCs subjected to gradient thermal cyclic test was primarily induced by sintering during high‐temperature exposure. A delamination model with multilayer splats was developed to assist in understanding the failure mechanism of TBCs through sintering‐induced delamination of the top coat. Based on the above‐described results, this study should aid in facilitating the lifetime evaluation of the TBCs, which are on active service at relatively lower temperatures, by an accelerated thermal cyclic test at higher temperatures in laboratory conditions.     

介质循环搅拌容器应用前景的分析

文章详细介绍了一种新型设备－介质循环搅拌容器，并详细对比了传统的机械搅拌容器的优缺点。     

小黄鱼酶解液生物脱腥效果比较

以感官评价得分(腥味值)为指标,经单因素及正交实验,比较酵母菌和混合乳酸菌在发酵过程中对小黄鱼多肽的脱腥效果。结果表明:酵母最佳脱腥条件为发酵温度35℃、发酵时间60min、酵母添加量0.3%、蔗糖添加量0.4%;乳酸菌脱腥最佳条件为发酵温度43℃、发酵时间7h、乳酸菌添加量3%、蔗糖添加量3%。脱腥效果显示乳酸菌为理想的脱腥剂。     

化学镀镍和镍/金在微电子领域中的应用及展望

介绍了化学镀镍和镍／金技术以及镍-磷层的电学性能，综述了其在倒装芯片凸焊点的UBM、印刷电路板和电感-电容-电阻LCR元件生产上的应用。展望了化学镀镍技术在微电子领域中的应用前景。     

表面疏水化热塑性淀粉材料的性能

用含有异氰酸酯基的预聚体对热塑性淀粉材料（TPS）表面进行了疏水化处理。研究了除层与TPS表面的反应性、涂层的疏水性能以及力学性能。红外光谱（IR）分析结果表明，预聚体与基体TPS之间进行了反应,为反应性涂层；TDI／蓖麻油体系涂层样品表面的疏水性能与TPS相比有很大的改善，而TDI／PEG涂层样品表面的疏水性差；另外，涂层对材料起到一定的增强作用。     

33%苯噻酰·异丙·苄可湿性粉剂的高效液相色谱分析

采用甲醇 水 (HAC)为流动相体系 ,C18反相柱为分析柱 ,紫外检测器进行检测的反相高效液相色谱法同时测定 33%苯噻酰·异丙·苄可湿性粉剂中三个有效成分的含量。该方法测定苯噻酰草胺、异丙甲草胺和苄嘧磺隆的标准偏差分别为 0 94、0 0 70、0 0 2 9,变异系数分别为 0 37%、1 4 4 %、0 85 % ,平均回收率分别 10 0 3%、99 7%、99 2 % ,线性相关系数分别为 0 99978,0 99992 ,0 99994。     

Synthesis and mesomorphic properties of side‐chain cholesteric liquid‐crystalline polymers containing menthyl groups

A series of new cholesteric liquid‐crystalline polysiloxanes ( P₁ – P₅ ) derived from menthyl groups were synthesized. The chemical structures of the monomers and polymers were characterized with Fourier transform infrared, ¹H‐NMR, ¹³C‐NMR, and elemental analyses. The mesomorphic properties and thermal behavior were investigated with differential scanning calorimetry, polarizing optical microscopy, thermogravimetric analysis, and X‐ray diffraction measurements. The influence of the polymer structure on the thermal behavior was discussed. The monomer diosgeninyl 4‐allyloxybenzoate exhibited a typical cholesteric oily‐streak texture and a focal‐conic texture. Polymers P₁ – P₅ showed thermotropic liquid‐crystalline properties. P₁ displayed a smectic fan‐shaped texture, P₂ – P₅ showed a cholesteric Grandjean texture, and P₆ and P₇ did not show mesomorphic properties. The experimental results demonstrated that the glass‐transition temperature and the clearing temperature decreased, and the mesomorphic properties weakened with an increasing concentration of menthyl units. Moreover, P₁ – P₅ exhibited wide mesophase temperature ranges and high thermal stability. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102:5559–5565, 2006     

工业炉条件下石灰石分解特性的数值研究

在石灰石悬浮态分解数学模型的基础上,结合水泥工业预分解炉的实际情况,系统分析了温度、CO2 含量、粒径和气流速度等因素对石灰石分解的影响。计算结果表明,对于粒径小于70 μm的颗粒,其反应过程受化学反应控制,随着粒径的进一步增大,传质因素的影响逐渐变得严重。温度是分解的首要影响因素,CO2含量和颗粒粒径的影响随着温度的升高迅速减弱,气流速度对分解的影响则可以忽略。分解反应后期进行缓慢,在低温(T<900℃)下,入窑分解率一般控制在85%左右较为合适。这些结论对工业分解炉的设计和操作有一定的指导意义。本文推导出的公式可以计算各种条件下石灰石的分解时间。     

基于插件技术的多目标指令集模拟器设计与实现

指令级模拟器是处理器及嵌入式系统设计的重要工具,也是进行系统体系结构软件设计评估、系统软件设计开发及软硬件协同开发的有利工具。传统的指令集模拟器大多针对特定目标系统而设计,具有极大的目标依赖性。文章提出了一种基于插件构建技术的方法,利用插件的独立性、封闭性和利于扩展的特性,极大提高了多目标系统的开发效率。