多媒体课堂教学投录像中的问题与对策

随着多媒体课堂教学不断普及，多媒体教学录像片制作越显重要。对多媒体课堂教学摄录像中遇到的一些新问题如画面构图、室内用光以及现场声音的录制进行分析并提出解决的办法。     

中心波长为28.5nm多层膜镜反射率测量

在“星光-Ⅱ”装置上以类Ne铬x射线激光作为标定源，以平场光栅谱仪为分光元件进行了285nm的Mo/Si多层膜反射镜效率测量.介绍了实验方法，给出了实验结果，本次研制的两块多层膜镜反射率分别为31%和9.6%. 关键词： x射线多层膜反射镜 反射率测量 x射线激光     

Exact stability regions for quartic polynomials

Given an arbitrary real quartic polynomial, we find the exact region containing the coefficients of the polynomial such that all roots have absolute values less than 1.     

ELLIPTIC CURVE CRYPTOGRAPHY BASED AUTHENTICATED KEY AGREEMENT WITH PRE-SHARED PASSWORD

Based on elliptic curve Diffie-Hellman algorithm, an Elliptic Curve Authenticated Key Agreement (ECAKA) protocol with pre-shared password is proposed. Its security relies on the Elliptic Curve Discrete Logarithm Problem (ECDLP). It provides identity authentication,key validation and perfect forward secrecy, and it can foil man-in-the-middle attacks.     

等离子体电极普克尔盒电光开关单脉冲过程数值模拟

采用流体模型对等离子体电极普克尔盒(PEPC)电光开关单脉冲过程进行了数值模拟分析.模型包括带电粒子连续性方程、动量守恒方程、电子平均能量方程及空间电位泊松方程.分别采用隐式指数差分格式，超松弛迭代法(SOR)和经典四阶龙格-库塔法(R-K)对带电粒子连续性方程，泊松方程和电子平均能量方程进行数值求解.模拟分析了PEPC单脉冲过程中的带电粒子浓度、电子温度、空间电场、PEPC的放电电流、晶体两侧电压和开关效率的时间演化特性.模型得出了PEPC中气体放电等离子体的微观物理过程与PEPC宏观参量的关系，对设计 关键词： 等离子体电极普克尔盒 电光开关 数值模拟 气体放电     

Ductile titanium alloy with low Poisson's ratio

We report a ductile beta-type titanium alloy with body-centered cubic (bcc) crystal structure having a low Poisson's ratio of 0.14. The almost identical ultralow bulk and shear moduli of approximately 24 GPa combined with an ultrahigh strength of approximately 0.9 GPa contribute to easy crystal distortion due to much-weakened chemical bonding of atoms in the crystal, leading to significant elastic softening in tension and elastic hardening in compression. The peculiar elastic and plastic deformation behaviors of the alloy are interpreted as a result of approaching the elastic limit of the bcc crystal under applied stress.     

The topological optimization for truss structures with stress constraints based on the exist-null combined model

A new exist-null combined model is proposed for the structural topology optimization. The model is applied to the topology optimization of the truss with stress constraints. Satisfactory computational result can be obtained with more rapid and more stable convergence as compared with the cross-sectional optimization. This work also shows that the presence of independent and continuous topological variable motivates the research of structural topology optimization. The project supported by the State Key Laboratory for Structural Analysis of Industrial Equipment, Dalian University of Technology.     

结构综合的曲线寻优近似解析方法

本文首次在结构优化领域应用曲线寻优近似解析方法，数值实验表明本文方法的效率较高     

壳体结构优化及其DDDU(W)新版本

本文建立了壳体结构优化的序列二次规划模型,对八节点等参壳单元做了优化处理,扩充了通用结构优化程序DDDU(W)的功能。文末算例表明了算法的合理性与有效性。