Probing the Vorticity in a Superconductor Rapidly Quenched from the Normal State

Topological defects such as vortices subsist for some time in a rapidly frozen superconducting film (W. H. Zurek, Phys. Rep. 276, 177, 1996). We propose to use as a probe of the vortex density the finite delay T _d, which, in narrow strips, exists between a current step and the voltage response. Technically, this amounts to driving a bridge into the localized hot-spot regime by means of a pump pulse (laser or electrical). Cooling of such films as epitaxial YBCO-on-MgO, or niobium-on-sapphire, requires only a few nanoseconds at low T. A time t later, a probe pulse is applied to measure T _d. The dependence t T _d is interpreted as a witness of the fossil vorticity, long after quenching into the zero-resistance regime.     

TV Program Recommendation for Multiple Viewers Based on user Profile Merging

Since today’s television can receive more and more programs, and televisions are often viewed by groups of people, such as a family or a student dormitory, this paper proposes a TV program recommendation strategy for multiple viewers based on user profile merging. This paper first introduces three alternative strategies to achieve program recommendation for multiple television viewers, discusses, and analyzes their advantages and disadvantages respectively, and then chooses the strategy based on user profile merging as our solution. The selected strategy first merges all user profiles to construct a common user profile, and then uses a recommendation approach to generate a common program recommendation list for the group according to the merged user profile. This paper then describes in detail the user profile merging scheme, the key technology of the strategy, which is based on total distance minimization. The evaluation results proved that the merging result can appropriately reflect the preferences of the majority of members within the group, and the proposed recommendation strategy is effective for multiple viewers watching TV together.     

Symmetry Breaking Constraints for Value Symmetries in Constraint Satisfaction

Constraint satisfaction problems (CSPs) sometimes contain both variable symmetries and value symmetries, causing adverse effects on CSP solvers based on tree search. As a remedy, symmetry breaking constraints are commonly used. While variable symmetry breaking constraints can be expressed easily and propagated efficiently using lexicographic ordering, value symmetry breaking constraints are often difficult to formulate. In this paper, we propose two methods of using symmetry breaking constraints to tackle value symmetries. First, we show theoretically when value symmetries in one CSP correspond to variable symmetries in another CSP of the same problem. We also show when variable symmetry breaking constraints in the two CSPs, combined using channeling constraints, are consistent. Such results allow us to tackle value symmetries efficiently using additional CSP variables and channeling constraints. Second, we introduce value precedence, a notion which can be used to break a common class of value symmetries, namely symmetries of indistinguishable values. While value precedence can be expressed using inefficient if-then constraints in existing CSP solvers, we propose efficient propagation algorithms for implementing global value precedence constraints. We also characterize several theoretical properties of the value precedence constraints. Extensive experiments are conducted to verify the feasibility and efficiency of the two proposals.     

基于信息论的连续属性离散化

使用信息论的方法进行连续属性的离散化，引入Hellinger偏差HD（Hellinger Divergence)作为每个区间对决策的信息量度量，从而定义切分点的信息熵，最终的离散化结果是使各区间的信息量尽可能平均，分析了HD度量在两种离散化方法中的作用，说明它在划分算法中运用比较理想，而在归并算法中则有局限。     

An efficient prototype merging strategy for the condensed 1-NN rule through class-conditional hierarchical clustering

A generalized prototype-based classification scheme founded on hierarchical clustering is proposed. The basic idea is to obtain a condensed 1-NN classification rule by merging the two same-class nearest clusters, provided that the set of cluster representatives correctly classifies all the original points. Apart from the quality of the obtained sets and its flexibility which comes from the fact that different intercluster measures and criteria can be used, the proposed scheme includes a very efficient four-stage procedure which conveniently exploits geometric cluster properties to decide about each possible merge. Empirical results demonstrate the merits of the proposed algorithm taking into account the size of the condensed sets of prototypes, the accuracy of the corresponding condensed 1-NN classification rule and the computing time.     

CSCW中的对象同步与合并

为了满足响应时间以及可靠性的要求,协同应用通常采用全复制的体系结构．由此带来的一个巨大挑战就是如何保证复制在各个协作站点处的对象的一致性以及获得一个公共状态,总结了在线和离线两种协作模式下的不同需求,在此基础上给出了相应的控制机制——在线模式下的对象同步算法和离线模式下的对象合并算法．这些机制已经在协作支撑平台Cova系统中实现,实际的应用表明,这些措施与其他机制一起能够很好地满足协同应用数据一致性的要求。     

程序设计中的逻辑分解技术

利用逻辑化简方法,给出了程序设计中的逻辑分解技术。分解技术能化简逻辑判断中的冗余命题,减少判断的运行时间。讨论了搜索技术的递归中如何使用分解技术。此外,对于划分类型的判断,分解技术退化成集合归并方法,化简判断更为方便。在实际程序设计中,合理使用分解技术能有效提升算法性能,使程序更为清晰易懂。