A model for specification and synchronization of data for distributed multimedia applications

As network technology provides the capability to handle multimedia traffic and the demand of multimedia services increases, protocols are required for effective communication of multimedia data in a distributed environment. Synchronization is one of the key issues in a multimedia system. Most of the current approaches do not support an integrated solution to the problem of synchronization. In this paper we propose a mechanism for synchronization of multimedia data in distributed environment where the accuracy of the protocol can be tailored to the application. The system model supports live and video-on-demand service. We present a scheme where the specification of the temporal requirements provided by the application can be directly mapped to obtain the information necessary to enforce the synchronization required. We present two examples of specifying the temporal requirements and process of obtaining the information and present performance results of our simulation studies.     

A game theoretical model for collaborative groups in social applications

In this paper, we address the problem of the free riding behaviour that takes advantage of collaborative educational social groups without contributing back to other participants posts. Free riders are active users who ask questions and draw knowledge from the community but provide very limited or no contributions back to it. Since the survival of a collaborative educational community is highly dependent on its active users and their contributions, motivating free riding users to take an active part would naturally augment the value the community provides and ensure its survivability. As a solution, we formally analyse the impact of the free riding behaviour by means of repeated game theory where classical and generous Tit for Tat are used. Such analysis shows the impact of such behaviour on educational communities and raises the need for other strategies that motivate free riding users to cooperate under the threat of being punished by cooperative ones; hence, we introduce reputation based Tit for Tat strategies. Our study suggests adding reputation as a parameter in users’ profiles in collaborative groups to improve their survivability.     

Knowledge-based system for collaborative process specification

This paper presents an ontology-based approach for the design of a collaborative business process model (CBP). This CBP is considered as a specification of needs in order to build a collaboration information system (CIS) for a network of organizations. The study is a part of a model-driven engineering approach of the CIS in a specific enterprise interoperability framework that will be summarised. An adaptation of the Business Process Modelling Notation (BPMN) is used to represent the CBP model. We develop a knowledge-based system (KbS) which is composed of three main parts: knowledge gathering, knowledge representation and reasoning, and collaborative business process modelling. The first part starts from a high abstraction level where knowledge from business partners is captured. A collaboration ontology is defined in order to provide a structure to store and use the knowledge captured. In parallel, we try to reuse generic existing knowledge about business processes from the MIT Process Handbook repository. This results in a collaboration process ontology that is also described. A set of rules is defined in order to extract knowledge about fragments of the CBP model from the two previous ontologies. These fragments are finally assembled in the third part of the KbS. A prototype of the KbS has been developed in order to implement and support this approach. The prototype is a computer-aided design tool of the CBP. In this paper, we will present the theoretical aspects of each part of this KbS as well as the tools that we developed and used in order to support its functionalities.     

A context-based model for Knowledge Management embodied in work processes

Knowledge Management has become a prominent subject for organizations, but often the information that flows in a well-defined design work process is not characterized and treated in such a way as to promote its reuse. We argue that context is a fundamental information resource for improving how activities and interactions are understood and carried on. Our premise is that it is important for organizational learning that decisions, solutions, discussions and actions executed in work processes should be retrievable. We describe an environment that supports the cycle of creating and dealing with information about activities and interactions, focusing on their context. A formal ontology-based representation of context is presented to support the use of this environment. Two case studies are described and their results analyzed. The goal of this paper is to discuss and specify mechanisms that can be used to collect contextual information within such an environment.     

H: A component-based specification language for heterogeneous applications

This paper presents H, a minimalistic specification language for designing heterogeneous software applications, particularly in the realms of robotics and industria, which takes advantage of a Component-Based Software Engineering (CBSE) approach. H copes with some of the most outstanding characteristics of these systems, like diversity at different levels (hardware platforms, programming languages, programmer skills), network distribution, real time and fault-tolerance. The H specification covers the life-cycle of any heterogeneous application. Its development system offers to the designer and/or builder a set of tools for specifying modules, generating code semiautomatically, debugging, maintenance, and a real time analysis of the system.     

A reusable structural design for mobile collaborative applications

Architecting mobile collaborative applications has always been a challenge for designers. However, counting on a structural design as a reference can help developers to reduce risks and efforts involved in system design. This article presents a reusable architecture which helps modeling the communication and coordination services required by mobile collaborative applications to support collaboration among users. This architecture has been used as a basis for the design of several mobile systems. Two of them are presented in this article to show the applicability of the proposal to real world collaborative systems.     

Information granularity model for evolving context-based fuzzy system

An information granule has to be translated into significant frameworks of granular computing to realize interpretability–accuracy tradeoff. These two objectives are in conflict and constitute an open problem. A new operational framework to form the evolving information granule (EIG) is developed in this paper, which ensures a compromise between interpretability and reasonable accuracy. The evolving information granule is initiated with the first information granule by translating the knowledge of the entire output domain. The initial information granule is considered an underfitting state with a high approximation error. Then, the EIG starts evolving in the information granule by partitioning the output domain and uses a dynamic constraint to maintain semantic interpretability in the output-contexts. The important criterion in the EIG is to determine the prominent distinction (output-context) in the output domain and realize the distinct information granule that depicts the semantics at the fuzzy partition level. The EIG tends to evolve toward the lower error region and realizes the effective rulebase by avoiding overfitting. The outcome on the synthetic and real-world data using the EIG shows the effectiveness of the proposed system, which outperforms state-of-the art methods.     

面向大数据复杂应用的GPU协同计算模型

大数据计算中存在流计算、内存计算、批计算和图计算等不同模式,各种计算模式有不同的访存、通信和资源利用等特征。GPU异构集群在大数据分析处理中得到广泛应用,然而缺少研究GPU异构集群在大数据分析中的计算模型。多核CPU与GPU协同计算时不仅增加了计算资源的密度,而且提高节点间和节点内的通信复杂度。为了从理论上研究GPU与多核CPU协同计算问题,面向多种计算模式建立一个多阶段的协同计算模型（p-DCOT）。p-DCOT以BSP大同步并行模型为核心,将协同计算过程分成数据层、计算层和通信层三个层次,并且延用DOT模型的矩阵来形式化描述计算和通信行为。通过扩展p-DOT模型描述节点内和节点间的协同计算行为,细化了负载均衡的参数并证明时间成本函数,最后用典型计算作业验证模型及参数分析的有效性。该协同计算模型可成为揭示大数据分析处理中协同计算行为的工具。     

Web协同应用中基于文档划分的一致性维护模型

针对已有的Web协同应用中的一致性维护方法会带来严重的服务器耗费问题,提出了一种基于文档划分的一致性维护模型。该模型在操作转换算法SLOT(symmetric linear operational transformation)的基础上引入文档划分的思想。从降低服务器通信和内存耗费的角度出发,结合用户数量和操作频率的变化,给出一种动态的文档划分策略及其实现算法。仿真实验结果表明,该模型可以有效地降低大规模协同应用中服务器的通信和内存耗费。     

A platform for P2P agent-based collaborative applications

The operational environment can be a valuable source of information about the behavior of software applications and their usage context. Although a single instance of an application has limited evidence of the range of the possible behaviors and situations that might be experienced in the field, the collective knowledge composed by the evidence gathered by the many instances of a same application running in several diverse user environments (eg, a browser) might be an invaluable source of information. This information can be exploited by applications able to autonomously analyze how they behave in the field and adjust their behavior accordingly. Augmenting applications with the capability to collaborate and directly share information about their behavior is challenging because it requires the definition of a fully decentralized and dependable networked infrastructure whose nodes are the user machines. The nodes of the infrastructure must be collaborative, to share information, and autonomous, to exploit the available information to change their behavior, for instance, to better accommodate the needs of the users to prevent known problems. This paper describes the initial results that we obtained with the design and the development of an infrastructure that can enable the execution of collaborative scenarios in a fully decentralized way. Our idea is to combine the agent-based paradigm, which is well suited to design collaborative and autonomous nodes, and the peer-to-peer paradigm, which is well suited to design distributed and dynamic network infrastructures. To demonstrate our idea, we augmented the popular JADE agent-based platform with a software layer that supports both the creation of a fully decentralized peer-to-peer network of JADE platforms and the execution of services within that network, thus enabling JADE multiagent systems (MASs) to behave as peer-to-peer networks. The resulting platform can be used to study the design of collaborative applications running in the field.     

A collaborative decision-making model for orientation detection

Orientation detection is a fundamental task for biological vision and machine vision. Hubel and Wiesel discovered the selectivity in a simple cell to stimulus of specific orientation, and proposed the famous feedforward model. The Hubel–Wiesel hypothesis attributes the orientation selectivity in a simple cell to the overlapping receptive field centers of its afferent LGN cells along a line, and therefore has several difficulties in the implementation. This paper proposes a collaborative decision-making approach of orientation detection using a double-layer neural network. The single estimation layer estimates the relative position of the contrast edge according to each bottom neuron's response to the contrast stimulus; and the collaborative-decision making layer determines the orientation by optimizing a least square with a unimodular constraint. This computational model cannot just account for orientation selectivity in a flexible way, but be applied to image processing. The statistical experiments found a satisfactory model configuration that balances the computational cost, effectiveness, and efficiency. The simulation experiments yield accurate results invariant to the contrast, and reasonably explain several visual illusions. Moreover, the proposed algorithm outperforms the related image processing algorithms on challenging natural images. The underlying neural mechanism of this model is compatible with the neurobiological findings, and is therefore appropriate for approaches of accomplishing higher level visual tasks.     

Tracking product specification dependencies in collaborative design for conflict management

The main difficulty associated with a collaborative design process is understanding the product data exchanged during the design. Efficient and effective coordination of design activities relies on a thorough understanding of the dependencies between shared product specifications throughout the entire development cycle. This paper explores the linkages between the design process features and product specification dependencies, and suggests ways of identifying and managing specification dependencies to improve collaborative process performance. Using a UML (Unified Modeling Language) specification, we propose a process traceability tool to track the design process in an ongoing manner. Based on the information captured, the dependencies between specifications involved in the tracked process are identified and inserted in a dependency network, which is maintained throughout the design process. A set of mechanisms is then proposed to qualify the identified dependencies. Extracting and qualifying specification dependencies could be useful in many design situations; for example, during an engineering change management process to assess impacts and study change feasibility, or during a conflict management process to assist designers in resolving conflicts and maintaining the coherence of the design process (knowing that change management is a tool to conduct conflict management). Special attention is paid to the conflict management process. By means of a case study, we show how the solution we propose can assist designers during the conflict management process.     

上下文场景识别模型的稀疏贝叶斯判别学习方法

在机器人场景识别问题中,将连续场景的相关性通过基于隐马尔可夫模型的上下文模型进行描述.采用不同于传统的使用生成模型方法学习上下文场景识别模型的方式,首先引入稀疏贝叶斯学习机对上下文模型中图像特征的后验概率进行建模,然后通过贝叶斯原理将稀疏贝叶斯模型与隐马尔可夫模型结合,提出一种能够实现上下文场景识别模型的判别学习方法.在真实场景数据库上的实验结果表明,由该方法得到的上下文场景识别系统具有很好的场景识别能力和泛化特性.     

Communication support for distributed collaborative applications

The development of distributed, multimedia, collaborative applications requires the resolution of communication issues such as concurrency control and temporal and causal synchronization of traffic over related data streams. Existing transport and/or session-layer protocols do not include the desired support for multistream, multipoint communication. In this paper, we propose new communication abstractions and mechanisms that facilitate the implementation of the necessary coordination and concurrency control semantics in a collaborative application. We propose a protocol suite called themultiflow conversation protocol (MCP) for the realization of these abstractions and describe its prototype implementation in an internetwork of workstations. The paper also describes our experience with the prototype and results of a performance evaluation.     

基于背景的个性化客户行为模型研究

针对商业客户的背景信息对其消费行为的影响问题,提出了一种基于背景的商业客户行为模型的构建方法。该方法不仅收集了包含三级粒度背景信息的某大学学生客户的网上交易数据并按依赖于交易数据项的统计量对客户进行分组,还利用朴素贝叶斯(NB和TAN)及分组和统计关系数据库(GAC-RDB)分类器学习了各客户分组的背景和非背景预测函数,同时使用各预测变量的受试者运行特征曲线下面积(AUC)值,对客户背景在预测客户购买行为时的作用进行了定量的比较和分析。研究结果表明:背景信息对客户特别是个性化客户(单一客户)的消费决策具有良好的预测效果。     

A distributed specification model and its prototyping

A specification model is described that is based on the finite-state machine but is distributed. The model allows the user to decompose a large system into separate views. Each view is a complete system in itself, and reveals how the whole system would behave as seen from a certain angle. Put together, the combined views present a complete picture of the whole system. The complexity of a large centralized system is thus distributed and subdued. The author offers a simple execution scheme for the model. Using a high-level state-transition language called SXL, constructs in the model are expressed as preconditions and postconditions of transitions. The execution scheme allows all the views in the model to proceed in a parallel but harmonious way, producing a working prototype for the modeled system     

A model measurement system for collaborative supply chain partners

The purpose of this paper is to understand business performance in the context of an electronic component company. This paper developed a system dynamics model that describes supply chain process structure and examines scenarios, as well. Thus, this study adopted the signal-to-noise (SN) ratio defined by the Taguchi method to evaluate the robustness of a specific supply chain behavior. Resulting in poor inventory cost performance with uncertainty demand, this paper shows how the factor delivery time and lead time of an order can improve performance. Finally, this paper serves as a guideline for decisions that require different inventory strategies.     

A model of job satisfaction for collaborative development processes

Modern software development relies on collaborative work as a means for sharing knowledge, distributing tasks and responsibilities, reducing risk of failures, and increasing the overall quality of the software product. Such objectives are achieved with a continuous share of the programmers’ daily working life that inevitably influences the programmers’ job satisfaction. One of the major challenges in process management is to determine the causes of this satisfaction. Traditional research models job satisfaction with social aspects of collaborative work like communication, work sustainability, and work environment.This study reflects on existing models of job satisfaction in collaborative environments, creates one for modern software development processes, and validates it with a retrospective comparative survey run on a sample of 108 respondents. In addition, the work investigates the impact on job satisfaction and its model of the agile practice of Pair Programming that pushes job sharing to the extreme. With this intent, the questionnaire also collected feedback from pair programmers whose responses were used for a comparative analysis. The results demonstrate that Pair Programming has actually a strong positive effect on satisfaction, work sustainability, and communication.     

A context-based object-oriented application framework for discrete event simulation

Applying object-oriented programming (OOP) to construct simulation programs has gained momentum in the research community. Major research efforts involved with object-oriented paradigm adopted in discrete-event simulation are reviewed in this paper, along with a simulation application framework proposed which provides special reusability mechanisms. This object-oriented simulation framework consists of three object elements, that is, model, service and scheduler. The relations and interactions among these elements are also demonstrated. In addition, the abstraction of a model under such a framework is reached by a special concept and implementation, referred to as the simulation context. Each simulation context is used to model a component sub-system, e.g. the control or physical flows of a manufacturing system. A practical system, CSIMT+ +, is also developed to validate the feasibility of such a simulation application framework. Furthermore, various forms of application models based on this framework are also illustrated.     

A methodology for engineering collaborative and ad-hoc mobile applications using SyD middleware

Today’s web applications are more collaborative and utilize standard and ubiquitous Internet protocols. We have earlier developed System on Mobile Devices (SyD) middleware to rapidly develop and deploy collaborative applications over heterogeneous and possibly mobile devices hosting web objects. In this paper, we present the software engineering methodology for developing SyD-enabled web applications and illustrate it through a case study on two representative applications: (i) a calendar of meeting application, which is a collaborative application and (ii) a travel application which is an ad-hoc collaborative application. SyD-enabled web objects allow us to create a collaborative application rapidly with limited coding effort. In this case study, the modular software architecture allowed us to hide the inherent heterogeneity among devices, data stores, and networks by presenting a uniform and persistent object view of mobile objects interacting through XML/SOAP requests and responses. The performance results we obtained show that the application scales well as we increase the group size and adapts well within the constraints of mobile devices.