Load mapping for seamless interface between hydrodynamics and structural analyses

This paper addresses the problem of a seamless interface between hydrodynamics and structural analyses. A pressure distribution on a hydro model computed from seakeeping analysis needs to be transferred to a structural model for evaluating structural strength and its integrity. However, due to the differences in the computation and representation methods for both analyses, the load on the hydro model may not be correctly transferred to the structural model, leading to a different load distribution on the structural model and resulting in some unbalanced force and moment components. In this paper, a method is proposed to solve this problem. A pressure distribution on the hydro model is mapped on the structural model through projection, and force and moment imbalances on the structural model are eliminated through optimization of the nodal forces on the structural model. Moreover, a viscous force distribution along the center of each member of the hydro model is transferred to the nodal forces on the structural model based on the minimum distance measure with resolving any force and moment imbalance. Examples are presented to demonstrate the validity of the proposed method.     

A multigrid finite element method for reaction-diffusion systems on surfaces

We develop a multigrid finite element approach to solve PDE’s on surfaces. The multigrid approach involves the same weights for restriction and prolongation as in the case of planar domains. Combined with the concept of parametric finite elements the approach thus allows to reuse code initially developed to solve problems on planar domains to solve the corresponding problem on surfaces. The method is tested on a non-linear reaction-diffusion system on stationary and evolving surfaces, with the normal velocity of the evolving surface depending on the reaction-diffusion system. As a reference model the Schnakenberg system is used, offering non-linearity and algebraic simplicity on one hand, and quantitative reference data on the other hand.     

A hybrid collaborative filtering method for multiple-interests and multiple-content recommendation in E-Commerce

Recommender systems apply knowledge discovery techniques to the problem of making personalized recommendations for products or services during a live interaction. These systems, especially collaborative filtering based on user, are achieving widespread success on the Web. The tremendous growth in the amount of available information and the kinds of commodity to Web sites in recent years poses some key challenges for recommender systems. One of these challenges is ability of recommender systems to be adaptive to environment where users have many completely different interests or items have completely different content (We called it as Multiple interests and Multiple-content problem). Unfortunately, the traditional collaborative filtering systems can not make accurate recommendation for the two cases because the predicted item for active user is not consist with the common interests of his neighbor users. To address this issue we have explored a hybrid collaborative filtering method, collaborative filtering based on item and user techniques, by combining collaborative filtering based on item and collaborative filtering based on user together. Collaborative filtering based on item and user analyze the user-item matrix to identify similarity of target item to other items, generate similar items of target item, and determine neighbor users of active user for target item according to similarity of other users to active user based on similar items of target item.In this paper we firstly analyze limitation of collaborative filtering based on user and collaborative filtering based on item algorithms respectively and emphatically make explain why collaborative filtering based on user is not adaptive to Multiple-interests and Multiple-content recommendation. Based on analysis, we present collaborative filtering based on item and user for Multiple-interests and Multiple-content recommendation. Finally, we experimentally evaluate the results and compare them with collaborative filtering based on user and collaborative filtering based on item, respectively. The experiments suggest that collaborative filtering based on item and user provide better recommendation quality than collaborative filtering based on user and collaborative filtering based on item dramatically.     

Experimental studies on passive dynamic bipedal walking

Passive dynamic walking is a gait developed, partially or in whole, by the energy provided by gravity. The research on passive dynamic bipedal walking helps create an understanding of walking mechanics. Moreover, the experimental passive dynamic research provides a base to compare and validate computer simulation results. An improved kneed bipedal walking mechanism was designed and built to study the passive gait patterns. The first aim of this study is to determine the equivalency of testing a passive dynamic biped walker on a treadmill to testing on a ramp. Based on the small difference between the gait patterns measured on the two test platforms, testing on a treadmill was found equivalent to testing on a ramp. Gait measurements were then conducted on the treadmill to evaluate the effects of the treadmill inclination angle, mass distribution of the biped, and the length of flat feet on the gait pattern. Results show that most of these parameters had significant effects on the step length, step period and hip velocity of the passive walker. Our experimental results are also compared with previous experimental results.     

地铁站楼梯行人流交通特征的数据拟合分析

随着中国城市化水平的不断提高,行人在整个城市交通体系中的影响越来越大,越来越多的研究开始关注行人交通。但目前国内外对行人交通的研究都集中在水平步道上,尚没有对楼梯的行人流特征的研究,特别是缺少对大城市重要人流重要集散地的步行楼梯行人流特征的分析研究。通过对上海市赤峰路轻轨车站、上海人民广场地铁站和上海火车站地铁站等几个重要的行人集散地的楼梯行人流的特征调查,以定性分析为基础得到楼梯行人流的密度－速度、密度－流率的函数关系类型,并采用Matlab等软件进行函数拟合,得到换乘枢纽的行人流特征函数及楼梯行人流特征模型。为合理设置换乘枢纽内楼梯设施,提高楼梯的通行能力,更好组织行人流提供依据。     

A schematic age-structured compartment model of the impact of antiretroviral therapy on HIV incidence and prevalence

A simple deterministic model is proposed to represent the basic aspects concerning the effects of different antiretroviral treatment schedules on HIV incidence and prevalence of affected populations. The model mimics current treatment guidelines applied in Brazil. However, the model does not intend to fit the data with any acceptable degree of accuracy since uncertainties on the values of the parameters and on the precise effect of the treatment put some limits on the practical implications of our model from which only orders of magnitude and some qualitative effects can be deduced. So, this paper intends to provide a conceptual and mechanistic understanding of the possible long-term effects of treatment on the dynamics of HIV transmission.According to the model, the effect of the treatment depends on the level of sexual activity of the subpopulations considered, being more pronounced on the subpopulations with the highest sexual activity levels. Also, inefficient treatment can be prejudicial depending on the level of sexual activity and on the capacity to provide adequate treatment coverages to the population affected.     

基于曲率的GPU 光线投射

基于曲率的体绘制十分有用,它可以帮助科学家分析数据特征,设计新的 数学模型。论文在GPU 上实现了基于B 样条滤波和基于线性滤波的按需计算导数、曲率和 光照效果的GPU 光线投射方法。实验结果表明,按需计算方法大大加速了基于B 样条滤波 的GPU 光线投射方法的绘制速度;线性滤波方法绘制速度快于B 样条滤波的方法;基于 B 样条滤波的方法绘制质量更高;可以利用线性滤波的方法交互选择相机设置、转换函数和曲 率函数,突出感兴趣的特征,然后用基于B 样条滤波的方法绘制高质量的图像。     

组件扩展方式下MIS数据的安全访问技术

Web方式下访问数据库服务器有三种方式：基于服务器端的扩展、基于客户端的扩展和基于组件的扩展。而组件扩展模型是实现三层客户／服务器模型应用系统的最新方案。本文讨论组件扩展方式下的数据安全访问技术。     

The impacts of competence-trust and openness-trust on interorganizational systems

Trust can have imperative influences on the use of interorganizational systems (IOSs). Management, sociology and psychology literature distinguish different types of trust and attribute distinctive impacts to these types. However, little is known regarding the influences of different types of trust on IOSs usage. This paper focuses on how trust based on partner competence and trust based on partner openness influence the use of IOS-related resources. Hypotheses are constructed relying on the use of the resource-based view and transaction-cost economics to analyse influences on relationship specificity of four types of IOS-related resources: business processes, human knowledge, organizational domain knowledge and IOS infrastructure. Three case studies are conducted on interorganizational relationships employing IOSs. Competence-trust is found to positively influence the use of human-knowledge resources, resources related to interlinkage of business processes and organizational domain knowledge resources. Openness-trust is found to positively influence use of human-knowledge resources and organizational domain-knowledge resources.     

Assessment of anti-slip devices from healthy individuals in different ages walking on slippery surfaces

The interest for effective preventive strategies for slips and falls is growing. Much remains to be done, however, to prevent slips and falls in the traffic environment. Using an appropriate anti-slip device may reduce the risk of slips and falls on different surfaces outdoors during winter. The aim of this study was to evaluate the best anti-slip devices of different designs in the Swedish market on a larger group of healthy individuals in different ages on five different slippery surfaces as a way to develop a standard method to test anti-slip devices. Three different designs of anti-slip devices: heel device, foot-blade device and whole-foot device were evaluated on ice surfaces uncovered or covered with gravel, sand, salt or snow. The evaluations were done according to subject's perceived walking safety and balance, videorecordings of walking postures and movements, time to take on and off each anti-slip device, advantages/disadvantages with each anti-slip device and a list of priorities for own use according to three criteria: safety, balance and appearance. The heel device was perceived to be the most safe on all five surfaces, followed by the toe device and the whole-foot device. The heel device was also perceived to be the one with the best walking balance on uncovered ice and on snow covered ice. There were some significant differences due to gender and age. Most subjects walked with a normal muscle function in the hip and knee when walking with or without an anti-slip device on all surfaces. The heel device was perceived as the most rapid one to take on and the toe device as the most rapid one to take off. All three devices were perceived as having a good foothold. The heel device was perceived to fit the shoe and to be stable at heel-strike. The toe device was easily portable and stable on uncovered ice. The whole-foot device was comfortable to walk with and safe on snow covered ice. The heel device had the highest priority according to walking safety, walking balance and choice for own use.     

无线局域网中的入侵检测研究与设计

介绍了一种适用于无线局域网的入侵检测方案。该方案分别实现了无线局域网的主机安全检测和网络安全检测。针对无线局域网的特点,该方案把基于嵌入式的入侵检测系统嵌入到移动终端作为基于主机的入侵检测系统,把基于移动Agent的入侵检测系统安装到MSS(Mobile Support Station,支持移动计算的固定站点)上用于实现基于网络的入侵检测。该入侵检测方案能有效消除无线局域网的来自主机与网络两方面的安全威胁。     

无线局域网中的入侵检测研究与设计

介绍了一种适用于无线局域网的入侵检测方案。该方案分别实现了无线局域网的主机安全检测和网络安全检测。针对无线局域网的特点,该方案把基于嵌入式的入侵检测系统嵌入到移动终端作为基于主机的入侵检测系统,把基于移动Agent的入侵检测系统安装到MSS（Mobile Support Station,支持移动计算的固定站点）上用于实现基于网络的入侵检测。该入侵检测方案能有效消除无线局域网的来自主机与网络两方面的安全威胁。     

The effects of organizational learning environment factors on e-learning acceptance

Workplace learning is an important means of employees’ continuous learning and professional development. E-learning is being recognized as an important supportive practice for learning at work. Current research on the success factors of e-learning in the workplace has emphasized on employees’ characteristics, technological attributes, and training design elements, with little attention to workplace contextual effects. The study aims to investigate the impacts of organizational learning environment factors, including managerial support, job support, and organizational support, on employees’ motivation to use a workplace e-learning system. A model was proposed based on the expectancy theory of training motivation and the social influences and facilitating conditions in technology acceptance models. The model was tested on sample data collected from mainland China using Structural Equation Modeling and Moderated Structural Equation Modeling. The results suggested that employees’ perceived managerial support and job support had a significant impact on their perceived usefulness of the e-learning system for individual learning, and that perceived organizational support had a significant influence on the perceived usefulness of the e-learning system for social learning. Perceived usefulness for individual learning was found to completely mediate the environmental influences on individuals’ motivation to use the system, while perceived usefulness for social learning made partial mediation in the effects of the environmental factors on intention to use. In addition, perceived job support was found to have moderating effects on the relationship between employees’ perceived usefulness of the e-learning system and their intention to use the system. Consistent with previous findings, employees’ perceptions about the usefulness of the e-learning system have significant effects on their intention to use the system in the work setting.     

一种FPGA验证与测试的方法介绍

如何快速开发FPGA测试平台以实现FPGA验证与测试是本文的研究重点。基于PC、ATE与自制应用型DUT板,对FPGA验证与测试开发技术进行研究。PC主要完成测试程序下载与调试验证工作,自制应用型DUT板实现对FPGA的配置,ATE等待FPGA配置完成后进行信号输入与输出验证。基于该理论对Xilinx公司的XC2S200进行了实验,实验表明该方法可行并能快速实现测试开发与芯片验证,且具有很好的通用性,可用于其他FPGA芯片的测试、研究与验证。     

Cooperative caging and transport using autonomous aquatic surface vehicles

We present a study on the cooperative control of two autonomous surface vehicles performing a caging and transport mission on the water surface. The two vehicles, connected to each other by means of a floating flexible rope, are required to capture a floating target from a given location, and transport it to a designated position. We focus on the coordination and control strategy to meet these requirements, and on its implementation on two under-actuated vehicles. We describe a multi-layered control architecture which achieves the goal, followed by simulation studies and field experiments with the two vehicles caging and transporting a floating target on the surface of a lake.     

Are models better read on paper or on screen? A comparative study

Is it really better to print everything, including software models, or is it better to view them on screen? With the ever increasing complexity of software systems, software modeling is integral to software development. Software models facilitate and automate many activities during development, such as code and test case generation. However, a core goal of software modeling is to communicate and collaborate. Software models are presented to team members on many mediums and two of the most common mediums are paper and computer screens. Reading from paper or screen is ostensibly considered to have the same effect on model comprehension. However, the literature on text reading has indicated that the reading experiences can be very different which in turn effects various metrics related to reader performance. This paper reports on an experiment that was conducted to investigate the effect of reading software models on paper in comparison with reading them on a computer screen with respect to cognitive effectiveness. Cognitive effectiveness here refers to the ease by which a model reader can read a model. The experiment used a total of 74 software engineering students as subjects. The experiment results provide strong evidence that displaying diagrams on a screen allows subjects to read them quicker. There is also evidence that indicates that on screen viewing induces fewer reading errors.

     

基于桥梁用户的多社交网络影响最大化

单社交网络影响最大化问题已经得到了学术界的广泛关注与研究,然而如今多社交网络之间呈现信息互通的趋势.多社交网络中存在的桥梁用户（Bridge User,BU）（即同时拥有多个社交网络账户的用户）,可将信息从一个社交网络分享至另外一个社交网络,信息传播不再局限于单个网络.本文针对多社交网络信息影响最大化进行了相关研究,分析了桥梁用户在多社交网络信息传播中的作用,提出了基于桥梁用户的多社交网络聚合算法,并在得到的聚合图上对多社交网络影响最大化问题进行求解.仿真实验对多社交网络影响最大化问题进行了求解,并证实了桥梁用户在多社交网络信息传播时的作用.     

基于Web的大规模语料库构建方法

低成本、短周期构建大规模语料库是目前研究工作的难点之一。该文提出一种建设大规模语料库的新方法,主要解决如何基于Web构建大规模的语料库及对语料库纠错,从而提高其质量。该方法利用网格技术的大规模计算能力与Wiki的开放编辑环境去收集和处理语料,根据可信度模型挑选出不可信的语料并由人工进行校对,计算校对后结果的可信度,选择出最可信的结果作为正确语料存储到语料库中。     

PAC-Bayesian Compression Bounds on the Prediction Error of Learning Algorithms for Classification

We consider bounds on the prediction error of classification algorithms based on sample compression. We refine the notion of a compression scheme to distinguish permutation and repetition invariant and non-permutation and repetition invariant compression schemes leading to different prediction error bounds. Also, we extend known results on compression to the case of non-zero empirical risk.We provide bounds on the prediction error of classifiers returned by mistake-driven online learning algorithms by interpreting mistake bounds as bounds on the size of the respective compression scheme of the algorithm. This leads to a bound on the prediction error of perceptron solutions that depends on the margin a support vector machine would achieve on the same training sample.Furthermore, using the property of compression we derive bounds on the average prediction error of kernel classifiers in the PAC-Bayesian framework. These bounds assume a prior measure over the expansion coefficients in the data-dependent kernel expansion and bound the average prediction error uniformly over subsets of the space of expansion coefficients.Editor Shai Ben-David     

Software quality assurance economics

ContextSoftware companies invest in quality assurance in order to lower software development and maintenance cost, and to increase revenue and profit margins. To contribute to increase of net income, a quality assurance organization has to consider cost and value of the testware involved in assuring quality of software artifacts, such as requirements, specifications, designs, and code.ObjectiveThis paper proposes a set of economic metrics: testware return on investment, inflation, and cost and value sensitivity to artifact changes and time passage. The paper proposes a set of guidelines on lowering testware cost, on increasing value, on maximizing return on investment, and on when to release.MethodThis paper presents an industrial case study data on the relation between test case cost and value, and on cost and value sensitivity to time passage and artifact changes.ResultsThe industrial case study showed return on investment on test cases of up to 200%, deflation of up to −2% per month, undesirable economic effects, such as test case cost outpacing test case value and rapid test case value depreciation based on time passage.ConclusionA viable QA organization should measure and improve test case return on investment, inflation, and cost and value sensitivity to artifact changes and time passage.