New techniques for designing qualitatively independent systems

Qualitatively independent systems, a previously recognized type of combinatorial design, have been recently shown to have industrial applications involving the testing of complex systems. For these applications, even small reductions on the size of a qualitatively independent system can be significant. This article discusses some new techniques that result in reduced constructions. © 1998 John Wiley & Sons, Inc. J Combin Designs 6: 411–416, 1998     

小尺寸破片对单兵防护装备的侵彻研究

为了探究了小尺寸破片是否能有效穿透普通单兵防弹衣与防弹头盔,以球型破片为对象,利用试验得出了0.2g钨合金球型破片侵彻Ⅲ级防弹衣与Ⅳ级防弹头盔的极限穿透速度;通过数值模拟的方法得出了防弹衣与防弹头盔的等效Q235靶板厚度,并探究了质量变化对破片极限穿透速度的影响规律。上述研究结论对新型高效反步兵武器与单兵基本防护装备的研制与开发都有重要的参考价值。     

On computations of stress intensity factors for stiffened half planes with imperfections and cracks

In this paper we consider uniform extension problems for joined two half-planes with different thickness and material behavior and one of which contains an elliptical hole, the other contains a crack. Along the boundary of these half-planes there is a stiffening stringer. Computational formulas are given in power series form by complex variable—pertubation method. Results obtained here give extension to those of Handbook of stress intensity factors. Numerical results of special cases in this paper coincide with those of refs. [1], [3].     

基于应力波传播机理的混凝土无损检测研究综述

混凝土结构在基础设施中应用广泛,但环境与荷载导致材料和结构的老化损伤问题,势必影响材料性能及耐久性和结构完整性及安全性．构建有效的混凝土材料性能评估和结构损伤识别体系是当前研究热点．现有研究因对应力波传播机理不深入理解、损伤定位定量模型理想化、损伤形式简化等问题仍存在局限性．因此,开发普适全面、稳定可靠的无损检测系统,对在建或既有混凝土结构服役状况进行长期、实时跟踪,具有重要学术意义和工程应用价值．本文结合混凝土无损检测领域的国内外研究现状及进展,从智能压电材料振动机理研究、混凝土无损检测方法发展、基于应力波的无损检测研究进展这三个逻辑层面,即按照研究手段到研究方法再到具体研究方案的顺序,循序渐进地对混凝土材料性能评估和结构损伤识别的研究进行了成果总结和方法提炼;基于此进一步概述了该领域所存在的瓶颈问题、研究重难点,最后提出了针对这些局限性的混凝土无损检测研究展望．     

Relationship between aerodynamic measures of glottal efficiency and stroboscopic findings in asymptomatic singing students

Singing requires exquisite coordination between the respiratory and phonatory systems to efficiently control glottal airflow. Asymptomatic singing students underwent pulmonary function testing (PFT), videostrobolaryngoscopic examination, and measures of glottal efficiency (maximum phonation time [MPT], glottal flow rate [GFR], and phonation quotient [PQ]) performed in both a sung and spoken tone. Pulmonary function and glottal efficiency values were within reported normative data for professional singers. However, sung tones were made with significantly higher GFR and PQ and lower PQ than spoken tones. The mean GFR was not related to the degree of glottal closure (by videostrobolaryngoscopy) or underlying pulmonary support.     

射线实时成像检测系统透视变换模型

以射线实时成像检测系统为研究对像 ,从透视成像的角度对射线实时成像检测系统的各个组成部分进行了较为详细的分析。将系统划分为射线透射环节、增强器成像环节、摄像系统变换环节和采集量化环节。从摄像机出发组建统一的坐标系 ,以此为基础 ,较为完整地建立了各成像环节的透视变换模型 ,为进一步进行缺陷的精确定位及定量分析打下了良好的基础。同时对其它相关应用场合也有实际意义     

Biaxial Mechanical Evaluation of Planar Biological Materials

A fundamental goal in constitutive modeling is to predict the mechanical behavior of a material under a generalized loading state. To achieve this goal, rigorous experimentation involving all relevant deformations is necessary to obtain both the form and material constants of a strain-energy density function. For both natural biological tissues and tissue-derived soft biomaterials, there exist many physiological, surgical, and medical device applications where rigorous constitutive models are required. Since biological tissues are generally considered incompressible, planar biaxial testing allows for a two-dimensional stress-state that can be used to characterize fully their mechanical properties. Application of biaxial testing to biological tissues initially developed as an extension of the techniques developed for the investigation of rubber elasticity [43, 57]. However, whereas for rubber-like materials the continuum scale is that of large polymer molecules, it is at the fiber-level (∼1 μm) for soft biological tissues. This is underscored by the fact that the fibers that comprise biological tissues exhibit finite nonlinear stress-strain responses and undergo large strains and rotations, which together induce complex mechanical behaviors not easily accounted for in classic constitutive models. Accounting for these behaviors by careful experimental evaluation and formulation of a constitutive model continues to be a challenging area in biomechanics. The focus of this paper is to describe a history of the application of biaxial testing techniques to soft planar tissues, their relation to relevant modern biomechanical constitutive theories, and important future trends. This revised version was published online in July 2006 with corrections to the Cover Date.     

文物铜车马部分残件的分析测试

对秦陵一号铜车马材质取样,采用电感偶合等离子体发射光谱法和塞曼石墨炉原子吸收光度法对其元素定性和定量分析;用光学金相显微镜扫描电镜观察金相组织状态;用能谱分析研究工艺;用X－射线衍射研究铜合金的组成结构和物相;配合电子探针做微区分析。分析的结果为铜车马的修复和保护起到了至关作用。     

利用实验室间国际比对验证15N丰度的测定能力

参加了由FAO／IAEA组合的全氮和^15N丰度检测能力验证的实验室国际间的比对两年的比对结果表明,我们实验室对3个植株样品全氮和^15N丰度的测定值与指定值十分吻合,检测结果准确,此项计划的实施,证明了本实验室的检测能力和国际实验室间的水平。