On transformations and shape functions for enhanced assumed strain elements

We summarize several previously published geometrically nonlinear EAS elements and compare their behavior. Various transformations for the compatible and enhanced deformation gradient are examined. Their effect on the patch test is one main concern of the work, and it is shown numerically and with a novel analytic proof that the improved EAS element proposed by Simo et al in 1993 does not fulfill the patch test. We propose a modification to overcome that drawback without losing the favorable locking-free behavior of that element. Furthermore, a new transformation for the enhanced field is proposed and motivated in a curvilinear coordinate frame. It is shown in numerical tests that this novel approach outperforms all previously introduced transformations.     

基于互感耦合原理的传感器设计

为精确测得应用于电子标签防盗系统(EAS)中的电子防盗标签的质量参数,根据标签的结构,提出了利用互感耦合原理对标签的质量参数进行检测的方法.研究了单线圈传感器模型和双线圈传感器模型结构特点,并分别对其进行了Matlab仿真分析.同时对双线圈传感器进行了设计制作和实验测试.研究结果表明,双线圈传感器检测效果好,而且该传感...     

Two‐ and three‐dimensional transition element families for adaptive refinement analysis of elasticity problems

In this paper, new enhanced assumed strain (EAS) and hybrid stress transition element families are developed for 2D and 3D adaptive refinement analysis of elasticity problems. The EAS element families are based on some existing incompatible transition element families. By using the EAS method and the previous incompatible modes, the B ‐matrix columns associated with the EAS modes can be directly designed such that their domain integrals vanish automatically and they can be computed more efficiently. For 2D hybrid stress transition element families, it is possible to derive different stress fields that lead to rank‐sufficient transition elements. However, the task becomes intractable for 3D hybrid stress transition elements in which many combinations of mid‐side and mid‐face nodes are possible. This paper proposes to use hybrid stress transition element families in which the assumed stress fields are linearly complete. The new 2D element family is more accurate than the 2D rank‐sufficient element family. The new 3D element family is more accurate than the one with additional bilinear stress modes. Numerical examples reveal that the most accurate transition element families are the newly developed hybrid stress families followed by the EAS families, the incompatible families and then the compatible families. Copyright © 2008 John Wiley & Sons, Ltd.     

用强化假定不连续应变实体单元分析弹性地基薄板

用强化假定不连续应变(EAS)实体单元离散弹性地基薄板,假设板上的荷载按分布力形式传递到地基中,根据半无限空间上任一点节点力与任一点处的位移关系用高斯积分法建立了地基表面分布力与节点位移关系表达式,在此基础上根据地基与板间的位移协调及静力平衡条件,建立了以板上的节点位移为未知量的有限元方程.算例分析表明,采用强化假定不连续应变实体单元分析薄板类问题是合理的,进行弹性地基薄板受力分析时考虑地基分布反力是必要的.     

EAS软标签的制造工艺分析

分析了电子防盗系统(EAS)软标签传统制作工艺的特点,提出用印刷技术和新型油墨制造EAS的思路和关键的技术点,以及目前面临的技术难题.     

基于ARM Cortex-M3的声磁商品电子防盗系统设计

针对普通EAS系统存在抗干扰性能差、检测灵敏度低、检测范围小、误报率高等缺点,设计了一种基于ARM Cortex-M3的声磁EAS系统。本文介绍了声磁EAS系统的工作原理和硬件结构框图,分析了声磁标签信号在时域和频域上的特征,提出了FFT信号频谱分析、信号互相关、最小二乘法拟合直线求取斜率、计算信号峰值数及峰值方差运算等多种检测声磁标签信号的算法,并详细描述了系统软件算法的设计。实验验证,本系统具有抗干扰性能强、检测灵敏度高、检测范围宽、误报率低等特点。     

基于Enterprise Application Studio的Web数据库

简要论述基于组件的应用开发及其多层体系结构 ,利用EnterpriseApplicationStudio工具包中的主要产品进行Web数据库应用开发的策略 ,并提出了解决方案     

基于精英蚂蚁算法的动态路由和波长分配研究

为了更有效地解决密集波分复用光网络中动态路由和波长分配问题,提高光网络中资源利用率,该文提出了一种基于精英策略蚂蚁系统算法的动态路由和波长分配问题的解决方法。在仿真中通过将精英策略蚂蚁算法应用到经典的美国国家科学基金会网络中,动态地完成路由和波长的分配。仿真结果表明,精英策略蚂蚁算法能够降低网络阻塞率,有效提高密集波分复用光网络的带宽资源利用率,并且随着波长数目或者网络负载的不断增加,这种优势更加明显。     

Curtailed electricity and hydrogen in Association of Southeast Asian Nations and East Asia Summit: Perspectives form an economic and environmental analysis

This study examines how well producing hydrogen via electrolysis from curtailed electricity from renewables could fulfil environmental benefits against the cost of producing hydrogen via electrolysis in the context of the Association of Southeast Asian Nations (ASEAN) and the East Asia Summit (EAS). The cost of producing hydrogen via electrolysis ranges from less than USD² per kgH₂ when the electrolyser load factor is 1500 h or above to USD10 per kgH₂ or even higher when the electrolyser load factor is 500 h or lower. The amount of CO₂ emissions abated by hydrogen produced from curtailed electricity from renewables ranges from about 130 million tonnes to about 150 million tonnes for ASEAN and from about 18,000 million tonnes to about 19,000 million tonnes for EAS. Applying prevailing carbon prices to the CO₂ emissions abated, the possible monetised benefits of hydrogen produced via electrolysis from curtailed electricity from renewables range from about USD0.25 per kgH₂ to about USD9.00 per kg H₂ for ASEAN and from about USD0.50 per kgH₂ to about USD15.00 per kg H₂ for EAS. The results of the cost-benefit analysis suggest that the price of carbon needs to be about USD15 per tonne of CO₂ to justify hydrogen produced via electrolysis from curtailed electricity from renewables for both ASEAN and EAS. The results also suggest that high electrolyser load factors make hydrogen produced via electrolysis from curtailed electricity from renewables cost-competitive even under low carbon prices.