On an invariance principle for unilateral contact at a bimaterial elastic interface

This paper examines the axisymmetric elastostatic problem related to the unilateral receding contact at a pre-compressed smooth bimaterial elastic interface. The separation at the interface is caused by the action of axisymmetric stress fields of unequal magnitude, which are applied at any location of the separate halfspace regions. The analysis of the problem focuses on the determination of the zone of separation as a function of the pre-compression, the magnitudes and locations of the axisymmetric stress fields inducing the separation, and the elasticity characteristics of the halfspace regions. It is found that the radius of the separation zone can be evaluated in explicit form. In the particular instance when the loadings applied at the surface of the halfspace regions are equal in magnitude and distribution, the analysis reveals that the radius of the separation zone is independent of the elasticity properties of the halfspace regions and can be evaluated in exact closed form.     

侵入物高速撞击下铰链式动车组的安全性

为探究侵入物高速撞击下铰链式动车组的安全性,在实物三维扫描重构的基础上,构建一种新的活体三维有限元层叠模型,并在LS-DYNA中进行摆锤侧面碰撞分析验证;通过铰链式动车组与活体在110 km/h速度下的碰撞仿真计算,讨论动车组运行的安全性以及吸能装置的可靠性.结果 显示:活体的有限元层叠模型既能保证计算精度,又能提高计算效率;在110 km/h的碰撞速度下,车体加速度为0.117g,轮对抬升量为0.238 mm,车钩每5 m长度的压缩量最大约为1.89 mm.各项指标都低于EN 15227标准,动车组行车安全性没有受到影响,吸能装置也能可靠工作.     

Aberrant protein expression in plasma and kidney tissue during experimental obstructive nephropathy

Kidney failure is a major health problem worldwide. Patients with end-stage renal disease require intensive medical support by dialysis or kidney transplantation. Current methods for diagnosis of kidney disease are either invasive or insensitive, and renal function may decline by as much as 50% before it can be detected using current techniques. The goal of this study was, therefore, to identify biomarkers of kidney disease (associated with renal fibrosis) that can be used for the development of a non-invasive clinical test for early disease detection. We utilized two protein-profiling technologies (SELDI-TOF MS and 2-D) to screen the plasma and kidney proteome for aberrantly expressed proteins in an experimental mouse model of unilateral uretric obstruction, which mimics the pathology of human renal disease. Several differentially regulated proteins were detected at the plasma level of day-3-obstructed animals, which included serum amyloid A1, fibrinogen α, haptoglobin precursor protein, haptoglobin and major urinary proteins 11 and 8. Differentially expressed proteins detected at the tissue level included ras-like activator protein 2, haptoglobin precursor protein, malate dehydrogenase, α enolase and murine urinary protein (all p<0.05 versus controls). Immunohistochemistry was used to confirm the up-regulation of fibrinogen. Interestingly, these proteins are largely separated into four major classes: (i) acute-phase reactants (ii) cell-signaling molecules (iii) molecules involved in cell growth and metabolism and (iv) urinary proteins. These results provide new insights into the pathology of obstructive nephropathy and may facilitate the development of specific assay(s) to detect and monitor renal fibrosis.     

The Painlevé paradox studied at a 3D slender rod

This paper aims at investigating the dynamical behaviors of a 3D rod moving on a rough surface with so-called Painlevé paradox. The condition for the occurrence of the Painlevé paradox in the rod is studied according to the theoretical results obtained from LCP’s method for spatial multibody systems. Numerical results obtained by inserting a compliant contact model into the rigid body model present a support for the assumption that a tangential impact is related to the spatial paradoxical situations. Furthermore, the tangential impact is analyzed by using the Darboux–Keller’s shock dynamics and are found with the same properties as the one in the planar rod: A tangential stick appears at the contact point during the impulsive process. With the help of the Stronge’s coefficient, an impact rule is developed to describe the dynamical behaviors of the 3D rod with paradoxical situations. Comparisons between numerical results obtained from Darboux’s model and the ones obtained from the compliant contact model are carried out and show well agreements.     

基于同态加密的云环境障碍最短路径导航的隐私保护算法

针对基于位置服务(LBS)中外包计算最短路径可能泄露用户隐私的问题,基于同态加密和安全多方计算,提出了一个基于同态加密的云环境障碍最短路径导航的隐私保护算法,为用户和数据所有者提供隐私保护.在该算法中,使用安全多方计算解决两种不同条件下计算道路中有无障碍物的最短路径隐私问题,并基于同态加密提出了有障碍物查询和无障碍物查询两个协议.最后,依照上述协议在理论和实践两个方面证明了所提出框架的有效性.     

障碍环境中线段组最近邻查询方法研究

为了解决现有成果无法有效处理障碍环境下的线段组最近邻查询问题,提出了障碍环境中线段组最近邻查询方法。查询过程分为过滤阶段和精炼阶段两个部分。在过滤过程中,首先根据线段Voronoi图的性质以及线段障碍组最近邻查询的定义,提出了针对数据线段的剪枝定理,并提出了OLGNN_Line_Filter算法;根据线段障碍距离的定义,进一步提出针对障碍物的剪枝定理,并给出了OLGNN_Obstacle_Filter算法。在精炼过程中,为了得到更精确的查询结果,提出了相应的精炼定理和精炼算法STA_OLGNN。理论研究和实验表明,所提算法能够有效地处理障碍环境下的线段组最近邻查询问题。     

江南古镇的街坊空间结构解析

街坊空间作为江南古镇的主体空间,由"间"、合院、院落组、地块等基本空间元素构成.由于居住情况变化、生活方式改变、古镇区主导性质变化等方面的原因,江南古镇街坊空间的形态日趋复杂化,空间结构从单向构成向双向构成模式转化.这种结构转化既是古镇街坊空间不断调整、发展从而适应新环境、满足新需求的过程,也是古镇街坊空间作为一个系统,自组织发展的过程.然而,由于缺少系统的规划和管理,这种结构的转化也造成了一些负面影响.     

穿甲弹异物阻滞膛炸机理数值仿真分析

以某穿甲弹近炮口处膛炸故障为背景,针对膛内存在异物时弹体和身管动态响应进行数值仿真,探讨膛炸机理并为故障分析与归零提供依据和参考。设定了两种典型异物阻滞形式：一是 异物阻滞造成弹体速度急剧下降或卡膛;二是弹体直接高速冲击膛内沙土类异物。采用有限元分析AUTODYN软件进行了多种不同工况数值计算,得到了弹体速度急剧下降时弹底燃气流场压力特征、身管变形与破裂形态,以及弹体高速冲击沙土类异物时结构动态响应、身管变形与破裂形态。研究结果表明：弹体膛内突然受阻和速度急剧下降,导致底部燃气中形成激波和局部高压区,局部高压区的存在可造成膛炸;弹体膛内近炮口处高速冲击沙土,身管受到复杂的强动载荷作用并可造成膛炸;数值仿真结果与实际故障情况相吻合并得到了故障复现试验的验证。     

基于三角形试验的引张线卡阻位置定位分析

引张线广泛应用于大坝水平位移监测,但在长期运行过程中会因线体卡阻而影响观测成果的真实性。因引张线的护管为不透明的PVC管或镀锌管,直接观察引张线卡阻部位存在一定难度,更换整根护管也显得不经济。为经济有效地消除卡阻,介绍运用三角形试验来准确判定卡阻位置的方法,并给出了相关计算公式。工程实例验证表明,该方法可准确找到卡阻位置,为以后引张线卡阻问题处理提供了参考。     

三山岛金矿新立分矿通风系统的研究及应用

新立矿井是新建大型黄金矿井,深度大,生产中段多,自投产以来,通风效果一直不理想,通过对矿井通风系统阻力测定数据的分析,提出通风系统的技改措施,并进行技术经济论证,以优化井下通风系统,达到建设经济节能型矿井目的。