考虑爬高效应的泥石流弯道超高公式

弯道超高是泥石流运动的显著特征。以往研究认为弯道超高完全是由于泥石流的离心运动造成的,未考虑泥石流在弯道运动时的冲起爬高效应。本文假设弯道超高和爬高分别由泥石流沿弯道的切向和法向速度引起,根据弯道处速度矢量三角形和圆弧三角形的几何相似关系,推导了考虑爬高效应的泥石流弯道超高公式。该公式依赖于弯道的内外曲率半径比、泥石流速度和沟壁倾角,适用于弯道圆心角小于60°和沟道较宽的情形。经云南东川蒋家沟的野外实际调查数据以及其他文献中的数据验证,与实测值误差较小,可用于泥石流弯道爬高的实际计算中。     

Shape optimization for a link mechanism

This paper presents a numerical solution for shape optimization problems for link mechanisms, such as a piston-crank mechanism. The dynamic behavior of a link mechanism is described by a differential-algebraic equation (DAE) system consisting of motion equations for each single body and constraints of linkages and rigid motions. In a shape optimization problem, the objective function to maximize is constructed from the external work done by a given external force, which agrees with the kinetic energy of the link mechanism, for an assigned time interval, and the total volume of all the links forms the constraint function. The Fréchet derivatives of these cost functions with respect to the domain variation, which we call the shape derivatives of these cost functions, are evaluated theoretically. A scheme to solve the shape optimization problem is presented using the H ¹ gradient method (the traction method) proposed by the authors as a reshaping algorithm, since it retains the smoothness of the boundary. A numerical example shows that reasonable shapes for each link such that mobility of the link mechanism is improved are obtained by this approach.     

无线多媒体传感器网络共享密钥发现协议设计与实现

无线多媒体传感器网络(WMSNs)是在传统无线传感器网络(WSNs)的基础上发展起来的具有音频、视频、图像等多媒体信息感知功能的新型传感器网络,具有广阔的应用前景.其网络安全通信已逐步得到研究人员的重视,鉴于无线多媒体传感器网络节点资源受限、分布式等特性,利用秘密同态和布隆过滤器,提出了一种安全高效的共享密钥发现协议,描述其具体设计流程并通过代码设计在嵌入式设备上得到了实现.     

Chemical modification of group IV graphene analogs

Mono-elemental two-dimensional (2D) crystals (graphene, silicene, germanene, stanene, and so on), termed 2D-Xenes, have been brought to the forefront of scientific research. The stability and electronic properties of 2D-Xenes are main challenges in developing practical devices. Therefore, in this review, we focus on 2D free-standing group-IV graphene analogs (graphene quantum dots, silicane, and germanane) and the functionalization of these sheets with organic moieties, which could be handled under ambient conditions. We highlight the present results and future opportunities, functions and applications, and novel device concepts.     

New pixel driving circuit using self‐discharging compensation method for high‐resolution OLED micro displays on a silicon backplane

A new 4T2C pixel circuit formed on a silicon substrate is proposed to realize a high‐resolution 7.8‐μm pixel pitch AMOLED microdisplay. In order to achieve high luminance uniformity, the pixel circuit compensates its Vth variation of the MOSFET for the driving transistor internally by using self‐discharging method. Also presented are 0.5‐in Quad‐VGA and 1.25‐in wide Quad‐XGA microdisplays with the proposed pixel circuit.     

A high-resolution transmission electron microscope study of a zinc oxide varistor

Investigations were made of varistor microstructure, the morphology of Bi₂O₃ at multiple ZnO grain junctions, Bi₂O₃/ZnO grain boundaries and ZnO/ZnO grain boundaries (especially whether Bi₂O₃ is present or not at the ZnO/ZnO grain boundary) by means of high-resolution transmission electron microscopy and X-ray microanalysis in the scanning transmission electron microscope. Bi₂O₃ at multiple ZnO grain junctions consists of small particles of 0.1m in diameter, and they are vitrified to some extent. It is suggested that bismuth ions dissolve into ZnO grains over a 30 nm range from a Bi₂O₃/ZnO grain boundary; however, there is no bismuth at ZnO/ZnO grain boundaries.     

云计算环境下基于密文策略的权重属性加密方案

在综合分析现有基于密文策略属性加密方案的基础上,针对现有基于密文策略属性加密方案较少考虑属性权重的现状,将权重的概念引入到基于密文策略的属性加密方案中,提出了基于密文策略的权重属性加密方案,证明了在选择权重属性集模型下安全性。并将此方案引入到云计算环境下,给出了系统级的基于密文策略的权重属性加密方案。分析表明,基于密文策略权重属性的加密方案相比现有方案更适用于云计算环境。     

会计资料失真及其法律责任探析

会计资料是资料使用评价财务状况、做出投资决策、改善经营管理、防范经营风险的主要依据。会计资料失真影响国家经济运行安全、造成会计行业信用危机、滋生与助长社会腐败现象。因此，如何规范会计行为，防范会计资料失真，维护正常的市场秩序，一直是众所关注的焦点。为此，笔将从会计资料失真的表现、原因、危害、法律责任和对策等角度对会计失真问题进行探析，以期能帮助人们深化认识和提高会计资料质量。     

基于VC++6.0开发的多功能数字显示程序

介绍图形编程、透明位图和图形防止闪烁的双缓冲技术。通过对“时频自动检定系统”中的设计实例,介绍在VC 中的多功能时间(数字)显示程序的设计方法。