半格分次弱Hopf代数的$G$-Cleft扩张

本文首先将Clifford幺半群代数分解为交叉积的半格直和,然后将这个结果通过$H$-$G$-cleft扩张推广到所谓的$G$-交叉积上.     

基于kinect和unity的虚拟手抓取碰撞检测算法

针对目前碰撞检测算法效率低精度差的问题,提出了一种改进的层次方向包围盒（OBB）算法。首先通过位置关系判断虚拟手是否在物体包围球的邻近区域,然后用OBB和八叉树算法进行详细的碰撞检测,最后利用离散点到虚拟手简化面的矢量计算法实现精确的碰撞检测。实验结果表明,随着三维物体基元数目的增多,这种由粗略到精确递进的检测方式极大的提高了碰撞检测的效率和精度,具有可行性。该算法适用于任何复杂场景中刚体结构模型的碰撞检测,在运行时候不存在滞后情况,显示流畅,而且碰撞检测精度高,完全能够满足虚拟环境实时性和精确性的要求。     

纳秒激光诱导等离子体发射光谱中的自吸收效应

为了减小激光诱导等离子体发射光谱中光谱线的自吸收效应,提高激光光谱分析技术对物质中高含量元素的检测水平,实验采用了一种平面反射镜装置约束等离子体,比较了有或无平面反射镜装置时光谱线的线型变化。实验表明,在无平面反射镜装置时,样品元素Al,Mg和Mn的光谱线半高全宽度分别为0.16,0.24,0.058nm,而采用由四块平面反射镜组成的装置在空间上约束激光等离子体时分别为0.11,0.13,0.047nm。结果表明,光谱线的自吸收明显减小,谱线线型变得比较锐且强度显著提高。通过观测等离子体照片,测量等离子体温度和电子密度,分析讨论了激光光谱自吸收效应降低的原因。     

相干态统计特性的弱测量结构研究

理论分析相干态位移参数估计在弱测量方法下的放大效应.引入偏振态作为附属态(Ancilla States),分别进行初选择和后选择,中间的相互作用采用了偏振相关的弱位移操作算符.通过最后检测光子数的分布来估计位移参数;在牺牲检测光子强度的情况下可以有效提高放大效应.     

导弹发射姿态测量方法研究

针对导弹发射姿态测量问题,提出采用高速摄像机通过斜瞄和平瞄姿态测量方法求解导弹中轴线俯仰角和方位角,仿真典型导弹起飞段近距离姿态测量,分析两种测量方法对导弹飞行姿态测量精度和适用性。仿真结果表明:平瞄和斜瞄姿态测量方法,测量误差在0.2°以内。斜瞄方式使用更便捷,通用性好。平瞄方式测量精度高,数据处理方法、机械结构相对简单,在适合的应用场合优势明显。此分析方法、分析结果为姿态测量方法选取和研究等提供一种可行的途径,也可为其它运动目标的姿态测量提供借鉴。     

Numerical solution to the buckling problem for a sandwich plate under uniaxial compression

A thin rectangular sandwich plate with isotropic linear elastic layers is considered. The plate is in a plane-strain state under uniaxial compression. An exact statement of the buckling problem is given. Its approximate solution is found by the finite-difference method. The concept of base scheme is used to formulate discrete problems in explicit and compact form. As an example, the critical parameters of the plate are calculated using a computation optimization procedure. Its efficiency is demonstrated __________ Translated from Prikladnaya Mekhanika, Vol. 42, No. 9, pp. 98–105, September 2006.     

Global attractors for the three-dimensional Navier-Stokes equations

In this paper we show that the weak solutions of the Navier-Stokes equations on any bounded, smooth three-dimensional domain have a global attractor for any positive value of the viscosity. The proof of this result, which bypasses the two issues of the possible nonuniqueness of the weak solutions and the possible lack of global regularity of the strong solutions, is based on a new point of view for the construction of the semiflow generated by these equations. We also show that, under added assumptions, this global attractor consists entirely of strong solutions.     

求解脉动速度关联函数的新方法及其在平面湍尾流中的应用

将周培源给出的平面湍尾流的一级近似解作为已知量,代入湍流脉动速度方程中,在微尺度范围内,采用谱方法对该方程进行数值求解,得到了和实验结果符合的二阶、三阶、四阶脉动速度关联函数的计算结果。     

A GEOMETRIC THEORY IN INVESTIGATION ON MODE LOCALIZATION AND FREQUENCY LOCI VEERING PHENOMENA

According to the mapping theory in complex plane,the geometric features of eigen fre-quency loci of systems undergoing free vibrations are investigated.It is concluded that the phenomenaof curve coalescence and veering can be described in a unified manner from the singularities of map-ping from the complex parameter plane onto the complex frequency plane.The formation of a branchpoint in the parameter space is the foundation of explaining localization and veering phenornena.Bythe use of condensation to reduce the dimension of a system,the scope of application of the geometrictheory is widely expanded.The theory is applied to examples to verify the validity of the proposed ap-proach.The present work is an improvement and extension of recent work by M.S.Traintafyllou etal.,