对区间上利用等价类解离散对数算法的改进

Pollard kangaroo算法是解决区间N上离散对数问题很有效的方法,在平均意义下需要进行2 √N次群操作.而Galbraith 和Ruprai对容易进行求逆运算的群,利用等价类的方法,将平均意义下需要的群操作次数降低到了1.36 √N.在Galbraith和Ruprai的基础上,对算法进行了优化,调整了家袋鼠和野袋鼠的活动区间,将区间分别变为了原来的0.8581倍,从而将平均意义下需要的群操作次数降低到了1.338√N.     

一种求解强凸优化问题的最优随机算法

随机梯度下降(SGD)算法是处理大规模数据的有效方法之一.黑箱方法SGD在强凸条件下能达到最优的O(1/T)收敛速率,但对于求解L1+L2正则化学习问题的结构优化算法,如COMID(composite objective mirror descent)仅具有O(lnT/T)的收敛速率.提出一种能够保证稀疏性基于COMID的加权算法,证明了其不仅具有O(1/T)的收敛速率,还具有on-the-fly计算的优点,从而减少了计算代价.实验结果表明了理论分析的正确性和所提算法的有效性.     

粗糙集的最优近似集

Pawlak教授提出的粗糙集理论是解决集合边界不确定的重要手段,他构建了边界不确定集合的两条精确边界,但没有给出用已有知识基来精确或近似地构建目标概念(集合)X的方法.在前期的研究中提出了寻找目标概念X的近似集方法,但并没有给出最优的近似集.首先,回顾了集合间的相似度概念和粗糙集的近似集R_λ(X)的构建方法,提出并证明了R_λ(X)所满足的运算性质.其次,找到了R_λ(X)比上近似集R(X)和下近似集R(X)更近似于目标概念X的λ成立的区间.最后,提出了R_0.5(X)作为目标概念的最优近似集所满足的条件.     

基于半边结构和√3细分的渐进网格生成方法

渐进网格可以满足生成多分辨率模型的需求.在现有渐进网格生成方法中,一个顶点的简化往往关联四个以上的相邻顶点.并且,现有方法多采用网格的点面列表结构表示.本文采用√3细分预测方法生成渐进网格,每个顶点的存储仅关联三个相邻顶点.同时也使用半边数据结构替代网格的点面列表表示形式,加快了邻接信息查询.实验结果表明,本方法提升渐进网格的空间效率,缩短渐进网格的生成时间.     

自然环境下的植物叶片智能色彩推理仿真

目的 在分析当前相关研究成果的基础上,提出植物叶片基于自然环境的色彩粗规律模型,为大场景植物动态仿真提供算法和理论依据。方法 该方法利用函数S-粗集,通过(F,F)-色彩粗规律给出动态色彩系统U的色彩生成算法和植物叶片色彩推理仿真,建立基于自然环境的植物叶片动态色彩系统建模理论。结果 实验结果表明,在基于双向S-粗集函数的植物叶片动态色彩系统理论中,对于阔叶植物叶片,当调整外部因素(如光照度、温度、湿度等)时,叶片的色彩也随之产生相应的变化,验证了植物叶片色彩粗规律理论的可靠性与有效性。结论 在植物叶片的智能仿真系统中,当外部因素变化时,植物叶片色彩的动态变化基本上符合自然环境中叶片的基本规律,是一种基于Billboard技术的用于解决大场景植物叶片色彩动态变化模拟和仿真的有效方法。     

一种具有O(1/T)收敛速率的稀疏随机算法

随机梯度下降(stochastic gradient descent,SGD)是一种求解大规模优化问题的简单高效方法,近期的研究表明,在求解强凸优化问题时其收敛速率可通过α-suffix平均技巧得到有效的提升.但SGD属于黑箱方法,难以得到正则化优化问题所期望的实际结构效果.另一方面,COMID(composite objective mirror descent)是一种能保证L1正则化结构的稀疏随机算法,但对于强凸优化问题其收敛速率仅为O(logT?T).主要考虑"L1+Hinge"优化问题,首先引入L2强凸项将其转化为强凸优化问题,进而将COMID算法和α-suffix平均技巧结合得到L1MD-α算法.证明了L1MD-α具有O(1?T)的收敛速率,并且获得了比COMID更好的稀疏性.大规模数据库上的实验验证了理论分析的正确性和所提算法的有效性.     

求解非光滑强凸优化问题的减小方差加权随机算法*

在光滑问题随机方法中使用减小方差策略,能够有效改善算法的收敛效果.文中同时引用加权平均和减小方差的思想,求解“L1+L2+Hinge”非光滑强凸优化问题,得到减小方差加权随机算法(α-HRMDVR-W).在每步迭代过程中使用减小方差策略,并且以加权平均的方式输出,证明其具有最优收敛速率,并且该收敛速率不依赖样本数目.与已有减小方差方法相比,α-HRMDVR-W每次迭代中只使用部分样本代替全部样本修正梯度.实验表明α-HRMDVR-W在减小方差的同时也节省CPU时间.     

模糊聚类计算的最佳算法

给出模糊关系传递闭包在对应模糊图上的几何意义,并提出一个基于图连通分支计算的模糊聚类最佳算法.对任给的n个样本,新算法最坏情况下的时间复杂性函数T(n)满足O(n)≤T(n)≤O(n²).与经典的基于模糊传递闭包计算的模糊聚类算法的O(n³logn)计算时间相比,新算法至少降低了O(n相似文献   

基于随机方差减小方法的DDPG算法

针对深度确定性策略梯度算法（DDPG）收敛速度比较慢,训练不稳定,方差过大,样本应用效率低的问题,提出了一种基于随机方差减小梯度方法的深度确定性策略梯度算法（SVR-DDPG）。该算法通过利用随机方差减小梯度技术（SVRG）提出一种新的创新优化策略,将之运用到DDPG算法之中,在DDPG算法的参数更新过程中,加入了随机方差减小梯度技术,利用该方法的更新方式,使得估计的梯度方差有一个不断减小的上界,令方差不断缩小,从而在小的随机训练子集的基础上找到更加精确的梯度方向,以此来解决了由近似梯度估计误差引发的问题,加快了算法的收敛速度。将SVR-DDPG算法以及DDPG算法应用于Pendulum和Mountain Car问题,实验结果表明,SVR-DDPG算法具有比原算法更快的收敛速度,更好的稳定性,以此证明了算法的有效性。     

并集问题的一个随机算法

随机算法由于其简洁和高效的特点正在计算中占据越来越重要的位置.但有时随机算法的优良性能并不要求用完全独立的随机变量作为它的输入.仅用成对独立的随机变量作为输入,得到了一个关于估计并集的基的问题的随机算法.这一方法可以减少随机算法中使用的随机位.对于固定的精确度ε和确信度δ,此算法需要O(t^1/2)的随机位,比标准的随机算法所使用的随机位数O(tlogtM)要少得多.而算法的执行时间并没有显著地增加O(t²logM).     

煤矿井下安全监控分站的设计及其仿真实现

为了设计一种具有低成本、低功耗、易操作、功能强且可靠性高的煤矿井下安全分站,针对煤矿安全生产实际,文章提出了采用MCS-51系列单片机为核心、具有CAN总线通信接口的煤矿井下安全监控分站的设计方案;首先给出煤矿井下安全监控分站的整体构架设计,然后着重阐述模拟量输入信号处理系统的设计过程,最后说明单片机最小系统及其键盘、显示、报警、通信等各个组成部分的设计;为验证设计方案的可行性与有效性,使用Proteus软件对设计内容进行仿真验证,设计的煤矿井下安全监控分站具有瓦斯、温度等模拟量参数超标报警功能和电机开停、风门开闭等开关量指示功能;仿真结果表明:设计的煤矿井下安全监控分站具有一定的实际应用价值.     

Call for Papers The 6^th International Conference on Grid and Cooperative Computing

Recent years have seen rapid advances in various grid-related technologies, middleware, and applications. The GCC conference has become one of the largest scientific events worldwide in grid and cooperative computing. The 6th international conference on grid and cooperative computing (GCC2007) Sponsored by China Computer Federation (CCF),Institute of Computing Technology, Chinese Academy of Sciences (ICT) and Xinjiang University ,and in Cooperation with IEEE Computer Soceity ,is to be held from August 16 to 18, 2007 in Urumchi, Xinjiang, China.     

View-based model-driven architecture for enhancing maintainability of data access services

In modern service-oriented architectures, database access is done by a special type of services, the so-called data access services (DAS). Though, particularly in data-intensive applications, using and developing DAS are very common today, the link between the DAS and their implementation, e.g. a layer of data access objects (DAOs) encapsulating the database queries, still is not sufficiently elaborated, yet. As a result, as the number of DAS grows, finding the desired DAS for reuse and/or associated documentation can become an impossible task. In this paper we focus on bridging this gap between the DAS and their implementation by presenting a view-based, model-driven data access architecture (VMDA) managing models of the DAS, DAOs and database queries in a queryable manner. Our models support tailored views of different stakeholders and are scalable with all types of DAS implementations. In this paper we show that our view-based and model driven architecture approach can enhance software development productivity and maintainability by improving DAS documentation. Moreover, our VMDA opens a wide range of applications such as evaluating DAS usage for DAS performance optimization. Furthermore, we provide tool support and illustrate the applicability of our VMDA in a large-scale case study. Finally, we quantitatively prove that our approach performs with acceptable response times.     

A pragmatic multi-method investigation of discrepant technological events: Coping,attributions, and ‘accidental’ learning

Discrepant technological events or situations that entail a problem, a misunderstanding or a difficulty with the Information Technology (IT) being employed, are common in the workplace, and can lead to frustration and avoidance behaviors. Little is known, however, about how individuals cope with these events. This paper examines these events by using a multi-method pragmatic approach informed by coping theory. The results of two studies – a critical incident study and an experiment – serve to build and test, respectively, a theoretical model that posits that individuals use a variety of strategies when dealing with these events: they experience negative emotions, make external attributions, and adopt engagement coping strategies directed at solving the event, eventually switching to a disengagement coping strategy when they feel they have no control over the situation. Furthermore, users’ efforts may result in ‘accidental’ learning as they try to overcome the discrepant IT events through engagement coping. The paper ends with a discussion of the results in light of existing literature, future opportunities for research, and implications for practice.     

The Distributed Time-Triggered Simulation Scheme: Core Principles and Supporting Execution Engine

Distributed real-time simulation is a young technology field but its practice is under increasing demands. In recent years the author and his collaborators have been establishing a new approach called the distributed time-triggered simulation (DTS) scheme which is conceptually simple and easy to use but widely applicable. The concept was initiated in the course of developing a new-generation object-oriented real-time programming scheme called the time-triggered message-triggered object (TMO) programming scheme. Some fundamental issues inherent in distributed real-time simulation that were learned during recent experimental studies are discussed along with some approaches for resolving the issues. An execution engine developed to support both the TMOs engaged in control computation and the TMOs engaged in DTS is also discussed along with its possible extensions that will enable significantly larger-scale DTSs.     

Software-Konfigurationsmanagement in großen Softwareprojekten

Zusammenfassung Mit zunehmender Größe der Softwaresysteme verschärfen sich die für die Software-Herstellung typischen Probleme: Beherrschen großer Objektmengen, Erhalten der Systemkonsistenz, Kontrolle der ständigen Änderungseinflüsse und Gewährleisten einer langen Lebensdauer. Die Disziplin Konfigurationsmanagement bildet den methodischen Ansatz, diese Probleme besser zu beherrschen. Software-Konfigurationsmanagement faßt die Herstellung von Softwaresystemen als eine Abfolge von kontrollierten Änderungen an gesicherten Zwischen- und Endergebnissen auf. Dargestellt werden die Objekte und Funktionen des Software-Konfigurationsmanagements sowie die hierfür in großen Software-Projekten benötigten Methoden, Instanzen und Hilfsmittel.     

Information for Authors

正http://www.zju.edu.cn/jzus http://www.springerlink.com Aim The Journals of Zhejiang University-SCIENCE(A/B/C)are edited by the international board of distinguished Chinese and foreign scientists,and are aimed to present the latest developments and achievements in scientific research in China and     

Editorial:Brain-machine interface(BMI) and cyborg intelligence

正Brain-machine interfaces(BMIs)aim at building a direct communication pathway between the brain and an external device,and represent an area of research where significant progress has been made during the past decade.Based on BMIs,mind information can be read out by neural signals to control     

Information for Authors

正http://www.zju.edu.cn/jzus http://www.springerlink.com Aim The Journals of Zhejiang University-SCIENCE(A/B/C)are edited by the international board of distinguished Chinese and foreign scientists,and are aimed to present the latest developments and achievements in scientific research in China and overseas to the world’s scientific circles,especially to stimulate     

SCIENCE CHINA Information Sciences SUBJECT INDEX TO VOLUME 57(2014)

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