The influence of microstructure on the failure behaviour of PEEK

In this study, different molecular weight PEEK materials were used to determine the effect of spherulite size on fracture. Melt processing of the PEEK at different temperatures produced samples of different average spherulite size. A permanganic etching technique was used to reveal the spherulites. It was found that for low molecular weight 150P PEEK, the spherulite size increased with melt processing temperature; but, for the higher molecular weight 450G PEEK, the spherulite size remained approximately constant. Also, the average spherulite size was markedly lower for the material of higher molecular weight. The failure behaviour of these samples was studied using a compact tension test. It was found that the fracture toughness of PEEK varied with processing temperature. Also, the average spherulite size of this material had a profound influence on the fracture mechanism.     

Aspects of strain measures and strain rates

Summary In finite homogeneous deformation processes, the principal triad generally rotates with respect to a material element during the deformation. The material derivative of the logarithmic strain is no longer simply related to the rate of deformation tensor, and this is exemplified herein. A mathematical procedure is provided for the analysis and the derivations vations are formulated using the co-rotational rate technique in hope, that this technique may be extended to other applications in future modeling. It will be apparent in the article that the co-rotational rate formulation provides a convenient mathematical procedure for handling problems in finite deformation.     

使用PKCS#11标准实现OpenVPN硬件加密算法

随着企业对使用互联网的安全需求大幅提高,VPN技术成为重要的解决方案。OpenVPN作为Linux下开源VPN的先锋,得到了广泛研究和应用。采用PKCS#11标准将硬件加密设备(KEY,一种智能密码钥匙)接入OpenVPN,使身份验证所需的数字证书能够通过硬件读写、存储,并且使VPN加密算法及加密/解密过程能够通过硬件实现,从而进一步提高OpenVPN的安全性能。     

力传感器用陶瓷双孔梁及其力学特性

研制了一种可用于应变式厚膜力传感器，量程达５００Ｎ的新型陶瓷双孔梁。该弹性梁采用９５％Ａｌ２Ｏ３瓷热压铸成型加工。应变电附为钌酸盐厚膜电阻，并直接印烧在弹性梁上。     

X射线衍射外推法精确测定晶胞参数

本文提出的晶胞参数精确测定方法是用测定晶体各个衍射谱线，利用新的外推函数消除系统误差，并根据最小二法求得最佳外推直线，得到精确的晶胞参数，实验分析表明，用这种方法可以得到精确的晶胞参数。     

Android安全性分析

从Android系统的系统框架入手,全面深入地分析了Android系统的安全机制与组成部分,进而得出Android面临的安全隐患与攻击行为。为增强Android的安全性,针对应用程序级攻击与内核级攻击行为．研究了XManDroid框架与基于logcat模式的内核行为分析框架,检测并阻止针对Android的恶意攻击行为,有效地保护了Android系统的安全。     

基于Lupas q-模拟Bernstein 算子的广义Bézier 曲线

提出了一种全新的广义Bézier 曲线。首先,从Lupas q-模拟Bernstein 算 子出发,得到了一组有理函数,该函数带有一个形状参数,是经典Bernstein 基函数的自然 推广。然后,构造了相应的广义Bézier 曲线,本文称之为Lupas q-Bézier 曲线,并研究了 其基本性质。Lupas q-Bézier 曲线具有与经典Bézier 曲线相类似的升阶公式和de Casteljau 算法。     

Streaming currents in microfluidics with integrated polarizable electrodes

A surface in contact with an aqueous solution is electrically characterized by the zeta potential. One way of determining indirectly the zeta potential of a surface is by measuring the streaming currents generated by a Poiseuille flow through a capillary channel with charged walls. We report measurements of streaming current in individual rectangular glass/PDMS microchannels with integrated miniaturized electrodes. Experiments performed using solutions with different salt concentrations and different electrode materials showed that the measured electrical current depends on the electrode material and in general differs from the real value of the streaming current. To determine the streaming current from the experimental data, an equivalent circuit model is proposed. The extracted value of the streaming current is proportional to the flow rate of electrolyte and the calculated glass/PDMS zeta potential scales linearly with the logarithm of the salt concentration. This work offers a thorough analysis of the effects that come into play during streaming current measurements and, in particular, it describes potential sources of error that can affect the streaming current measurements and suggestions on how to correct the measured values.     

The mixed-product assembly line sequencing problem of a door-lock company in Taiwan

This paper investigates the mixed-product assembly line sequencing problem in the door-lock manufacturing industry. Companies in the door-lock industries schedule their production processes to minimize their costs while meeting customer demand. The variances and diversities of each lock’s components complicate the mixed-product assembly line sequencing problem and directly influence the material requirement planning and human resource costs. In the current research, we study one of the largest ironware manufacturing companies in Asia, company F. For this company, an export-oriented strategy makes its main products (such as door locks and door closers) available around the globe. The primary customers of company F are the largest home improvement co-op stores (such as Home Depot, Lowe’s and True Value in the US) from the region of North America. The sales from this region account for over 80% of company F’s total sales. The remaining company sales are geographically distributed around the world in areas such as Europe, Asia and Australia. However, as labor cost is the major concern, this company seeks supply sources in southeast Asia, China and Taiwan. In this paper, we analyze company F and formulate an integer programming mathematical model with constraints regarding production lines, labor, warehouse capacity and order fulfillment rates to minimize the total cost. The customer demand is derived from real data from company F. We use the branch and bound algorithm (CPLEX) to solve this problem and analyze the results. Salient results and practical issues involved in this unique problem are discussed in detail in this paper.