云环境下高效视频传输关键技术

云计算对信息技术本身及其应用产生了深刻的影响,它将大量计算资源、存储资源与软件资源链接在一起,形成巨大规模的共享虚拟IT资源池,为远程计算机用户提供方便快捷透明的IT服务,并具有资源虚拟化、动态可扩展等特点.视频作为多媒体网络中的重要组成部分,并具备其他资源不同的特点,云计算也给高效视频传输带来了新的解决思路和挑战.     

Dynamic Niching Genetic Algorithm with Data Attraction for Automatic Clustering

A genetic clustering algorithm was developed based on dynamic niching with data attraction. The algorithm uses the concept of Coulomb attraction to model the attraction between data points. Then, the niches with data attraction are dynamically identified in each generation to automatically evolve the optimal number of clusters as well as the cluster centers of the data set without using cluster validity functions or a variance-covariance matrix. Therefore, this clustering scheme does not need to pre-specify the number of clusters as in existing methods. Several data sets with widely varying characteristics are used to demonstrate the superiority of this algorithm. Experimental results show that the performance of this clustering algorithm is high, effective, and flexible.     

完全二叉树相邻结点最近共同祖先的一种快速算法

寻找二叉树中两结点的最近共同祖先问题一直是图论与计算机科学关注的问题.首先,证明了完全求解二叉树相邻结点最近共同祖先的一个定理,该定理的求解方法主要涉及到位运算,无需递归搜索,既易于软件编程实现又易于通过硬件实现,然后给出了一个具有对数时间复杂度O（lnn）的快速算法及C＋＋示例.     

适用于数字对象的保密比较协议

分析了现有保密比较协议无法使用于不确定数字对象比较的原因,用随机构造单向散列函数的方法设计了对不确定具体范围的数字对象进行比较的一种多方保密计算方案,协议能以零泄漏的方式快速比较两个数字对象是否相同.用广泛接受的模拟范例证明了方案的保密性.     

Quantum programming: From theories to implementations

This paper surveys the new field of programming methodology and techniques for future quantum computers, including design of sequential and concurrent quantum programming languages, their semantics and implementations. Several verification methods for quantum programs and communication protocols are also reviewed. The potential applications of programming techniques and related formal methods in quantum engineering are pointed out.     

无推力可控弹可达域和投放域计算

传统炸弹的火控系统中主要采用连续计算命中点CCIP和连续计算投放点CCRP攻击方式。对无推力可控弹在一定投放条件下构成的弹着点区域进行了计算分析，采用对角度积分的快速积分算法，快速确定区域边界。根据无推力可控弹所具有的可达域的概念，提出了连续计算可达域CCAR和连续计算投放域CCRR攻击方式。充分利用了可控弹的可操纵性，降低了瞄准误差要求。     

超导量子比特中的Landau-Zener-Stckelberg干涉

超导量子比特是人工固态量子系统,在低温和弱耗散条件下,具有量子化的能级结构.这些能级之间的间隔可以随外加偏置电磁场连续变化,不同能级在某些偏置场可能形成量子系统中所特有的免交叉.最近研究成果表明,利用这些免交叉,可以在固态量子比特中实现Landau-Zener-Stckelberg（LZS）干涉,为测量系统的能谱、表征系统与环境的耦合、实现量子逻辑门、产生量子纠缠等提供了一个便捷的新手段.     

A liquid helium temperature target with a 10 K vapor shield for shock compression experiment in the environment condition of 100 Pa

The shock compression experiment of liquid helium is an available way to gain properties of specimen at high temperatures and pressures.Based on Fluent,a thermal insulation analysis and design of a liquid helium temperature target in the environment condition of 100 Pa for shock compression experiment is performed.Then,a cryogenic target with a 10 K helium vapor shield and a separated vacuum interval is particularly developed.A lowest temperature of 3.63 K and a stable temperature of 3.70 K in the specimen cavity with an accuracy of 0.1 K are obtained by means of continuous flow and vacuum cooling.Both time-consuming and temperature stability are well-suited to the requirements of the shock compression experiment.The results show that the calculated and experimental data well-matched each other.The simulation method may be effective and feasible for the optimal design of the cryogenic target.     

高炉冷却壁温度场分布与热流强度的关系

本文阐述了高炉冷却壁在稳定状态下的温度分布的数值解析方法，分析了热流程度对铜冷却壁和铸铁冷却壁最高温度的影响。比较了铜冷却壁与铸铁冷却壁的优劣。     

复杂电力系统次同步谐振的选择模式分析法

文章首次提出了分析电力系统次同步谐振的选择模式分析方法，与全特征值分析法相比，该方法大大降低了计算量及内存需求，从而解决了考虑机组轴系间相互影响时多机系统次同步谐振分析问题。