Neural networks in virtual reference tuning

This paper discusses the application of the virtual reference tuning (VRT) techniques to tune neural controllers from batch input-output data, by particularising nonlinear VRT and suitably computing gradients backpropagating in time. The flexibility of gradient computation with neural networks also allows alternative block diagrams with extra inputs to be considered. The neural approach to VRT in a closed-loop setup is compared to the linear VRFT one in a simulated crane example.     

Inter-domain service management of broadband virtual private networks

The emergence of an open market for telecommunication services provides a wide range of opportunities for the provision of value-added services by providers other than public network operators. One service already available today is a Virtual Private Network (VPN) that provides dispersed corporate sites with wide-area data communication capabilities using public network services. The introduction of Broadband ISDN allows for the provision of VPN services in a more integrated fashion. However, any effective VPN service must be able to deal with the technological and organizational heterogeneities that are present when providing a high level of service functionality over an arbitrary number of administrative and technological domains. This paper presents a management service for a VPN service that addresses some multi-domain and network heterogeneity issues. It outlines how a design based on the ITU-T's Telecommunications Management Network (TMN) Recommendation was developed and how working prototypes were implemented over real broadband networks.     

CORM: A reference model for future computer networks

This paper acknowledges the need for revolutionary designs to devise the Future Internet by presenting a clean-slate Concern-Oriented Reference Model (CORM) for architecting future networks. CORM is derived in accordance to the Function–Behavior–Structure engineering framework, conceiving computer networks as a distributed software-dependent complex system. CORM networks are designed along two main dimensions: a vertical dimension addressing structure and configuration of network building blocks; and a horizontal dimension addressing communication and interaction among the previously formulated building blocks. For each network dimension, CORM factors the design space into function, structure, and behavior, applying to each the principle of separation of concerns for further systematic decomposition. Perceiving the network as a complex system, CORM constructs the network recursively in a bottom–up approach starting by the network building block, whose structure and behavior are inspired by an evolutionary bacterium cell. Hence, CORM is bio-inspired, it refutes the long-endorsed concept of layering, it accounts intrinsically for emergent behavior fostering network integrity and stability. We conjecture that networks designed according to CORM-based architectures can adapt and further evolve to better fit their contexts. To justify our conjecture, we derive and simulate a CORM-based architecture for ad hoc networks.     

A new approach to model virtual channels in interconnection networks

Dealing with virtual channels has always been a critical issue in developing analytical performance models for interconnection networks. Almost all previous studies relied on a method proposed by Dally to capture the effect of virtual channels multiplexing in the performance of interconnection networks. This paper presents a new method to model the effect of virtual channel multiplexing in high-speed wormhole-switched interconnection networks. Dally's method loses its accuracy as the traffic load increases due to blocking nature of wormhole-switched networks. Our new method is based on a finite capacity queue, M/G/1/V and comparing to Dally's method achieves a higher degree of accuracy under low, moderate and high traffic loads. Furthermore, its simplicity eases its employment under different network conditions and setup. The presented model is validated by means of an event driven simulator and a detailed comparison with Dally's method is presented.     

A reference model approach to stability analysis of neural networks

In this paper, a novel methodology called a reference model approach to stability analysis of neural networks is proposed. The core of the new approach is to study a neural network model with reference to other related models, so that different modeling approaches can be combinatively used and powerfully cross-fertilized. Focused on two representative neural network modeling approaches (the neuron state modeling approach and the local field modeling approach), we establish a rigorous theoretical basis on the feasibility and efficiency of the reference model approach. The new approach has been used to develop a series of new, generic stability theories for various neural network models. These results have been applied to several typical neural network systems including the Hopfield-type neural networks, the recurrent back-propagation neural networks, the BSB-type neural networks, the bound-constraints optimization neural networks, and the cellular neural networks. The results obtained unify, sharpen or generalize most of the existing stability assertions, and illustrate the feasibility and power of the new method.     

虚拟组织服务资源的优化配置模型

为了提高虚拟组织服务资源配置的效率,提出了以服务成本、服务时间、服务满意度为目标的资源优化配置模型,采用遗传算法进行求解。在求解中为提高遗传算法的搜索性能,对不可行染色体进行筛选,同时在交叉变异过程中利用邻域搜索提高算法的收敛速度。通过一个具体的实例验证了遗传算法在资源优化配置模型中的有效性。     

Integrating reliability and quality of service in networks with switched virtual circuits

In this paper, we present an optimization model based on cost minimization for traffic engineering of multirate and ATM networks with switched virtual circuits (SVCs). There is an increasing interest for efficient traffic engineering methods for routing and dimensioning of large and robust multiservice networks. In the case of ATM and other types of packet multiservice networks, traffic engineering requires resource allocation and performance optimization at the cell or packet level in order to assure a satisfactory grade of service (GoS) at the call level to the users. Therefore, we are interested in networks with switched connections that are flexible enough so that planners may offer cost-effective networks with guaranteed GoS even in the event of important failures. The model integrates the notions of QoS, GoS, failures and failure propagation between the physical and the logical level as well as circuit routing.     

Reconfiguration for service and self-healing in ATM networks based on virtual paths

This paper presents a reconfiguration scheme resulting in capacity efficiency and fast restoration by utilizing the inherent benefits of Virtual Paths in ATM networks. The unified optimization of bandwidth reconfiguration is addressed so that switched ATM networks can support both service and survivability from a common pool of network spare capacity at a given time. The spare capacity is composed of idle bandwidth and freed up bandwidth from the switch pairs which have a surplus bandwidth. Fast restoration can be achieved by using the pre-optimized network spare bandwidth and preplanned backup Virtual Paths based on the link and node disjoint path routing scheme. The overall operation of the proposed self-healing strategy can be consolidated into distributed fault management functions at ATM layer based on Virtual Paths. The scheme enables a logical Virtual Paths ring protection switching in ATM networks.     

A reference architecture for scientific virtual laboratories

Recent advances in the IT can be applied to properly support certain complex requirements in the scientific and engineering domains. In experimental sciences, for instance, researchers should be assisted with conducting their complex scientific experimentation and supporting their collaboration with other scientists. The main requirements identified in such domains include the management of large data sets, distributed collaboration support, and high-performance issues, among others. The virtual laboratory project initiated at the University of Amsterdam aims at the development of a hardware and software reference architecture, and an open, flexible, and configurable laboratory framework to enable scientists and engineers with working on their experimentation problems, while making optimum use of modern information technology approaches. This paper describes the current stage of design of a reference architecture for this scientific virtual laboratory, and focuses further on the cooperative information management component of this architecture, and exemplifying its application to experimentation domain of biology.     

A stochastic evolutionary coalition game model of secure and dependable virtual service in Sensor-Cloud

Various intrusion detection systems (IDSs) have been proposed in recent years to provide safe and reliable services in cloud computing. However, few of them have considered the existence of service attackers who can adapt their attacking strategies to the topology-varying environment and service providers’ strategies. In this paper, we investigate the security and dependability mechanism when service providers are facing service attacks of software and hardware, and propose a stochastic evolutionary coalition game (SECG) framework for secure and reliable defenses in virtual sensor services. At each stage of the game, service providers observe the resource availability, the quality of service (QoS), and the attackers’ strategies from cloud monitoring systems (CMSs) and IDSs. According to these observations, they will decide how evolutionary coalitions should be dynamically formed for reliable virtual-sensor-service composites to deliver data and how to adaptively defend in the face of uncertain attack strategies. Using the evolutionary coalition game, virtual-sensor-service nodes can form a reliable service composite by a reliability update function. With the Markov chain constructed, virtual-sensor-service nodes can gradually learn the optimal strategy and evolutionary coalition structure through the minimax-Q learning, which maximizes the expected sum of discounted payoffs defined as QoS for virtual-sensor-service composites. The proposed SECG strategy in the virtual-sensor-service attack-defense game is shown to achieve much better performance than strategies obtained from the evolutionary coalition game or stochastic game, which only maximizes each stage's payoff and optimizes a defense strategy of stochastic evolutionary, since it successfully accommodates the environment dynamics and the strategic behavior of the service attackers.     

Towards a reference service model for the Web of Services

This paper introduces a reference service model (RSM) that closes the gap between two phenomenically contradictory service annotation paradigms: traditional semantic service frameworks and the emerging social annotation of services. RSM aims to (i) facilitate the semantic interlinking between services annotated using different semantic models and (ii) accommodate the bottom-up social annotation of services. RSM was developed following the design science research methodology. To develop RSM, existing semantic service models and SOA service models were reviewed in the light of the six service contracts and examined whether and using which elements each of the models supports in each of the contracts. The identified elements were then fed to a multiphase abstraction exercise. RSM comprises of the following concepts: Service, Service Input, Service Output, Service Context and Service Logic, Service Provider, Service Client and Service Feedback. The paper also maps the concepts of RSM to those of existing semantic service models and positions RSM with respect to related SOA service models. Finally, an implementation of RSM in OWL and two pilot developments that highlight different aspects of RSM are discussed.     

基于模型参考和神经网络的传感器动态补偿器的设计

为了改善传感器的动态响应特性,提出了一种动态补偿器的设计方法.该方法在传感器后接一基于模型参考自适应方法的动态补偿器,并利用BP神经网络算法不断在线辨识补偿器参数,使其始终工作在最佳参数下,实现动态性能的在线补偿.试验表明,对动态品质较差的双孔悬臂梁式压力传感器进行在线补偿,其到达稳态值的调节时间由0.1 s缩短为0.015 s,动态性能得以较好的改善.该方法为提高传感器性能开辟了新途径.     

Complex service design: A virtual enterprise architecture for logistics service

This paper presents an interdisciplinary systems approach to service modeling, design and deployment. The study is based on a longitudinal case study of the development process of a complex logistic service system based on an advanced logistics model. The case examines the development of a Virtual Enterprise Architecture (VEA) for an automatic high-speed transport and sorting system applied in airports for baggage handling. The study traces the evolution of the system from the early conceptual phases to a successful commercial service deployed at Changi, Singapore Airport. The study is conducted using a retrospective analysis of the case using a design science research approach. The paper evaluates and discusses the issues of creating and designing a new complex logistics service, distinct from the physical product, based on an advanced discrete event-based simulation model. The paper concludes by presenting a generalized and validated conceptual framework for a VEA based on an advanced simulation model. The paper thus contributes to the field of service systems and service management by identifying a novel approach to effective design of a new service.     

基于虚拟参考反馈整定的改进无模型自适应控制

针对一类离散时间非线性系统, 提出一种基于虚拟参考反馈整定的改进无模型自适应控制方案. 首先, 利用动态线性化方法给出非线性系统的紧格式动态线性化模型; 然后, 基于优化技术设计控制算法和伪偏导数估计算法; 最后, 设计基于虚拟参考反馈整定的伪偏导数初值和重置值的估计算法. 该控制方案设计仅依赖于被控系统的输入和输出数据, 且能保证闭环系统的稳定性和收敛性. 仿真比较结果验证了所提出方法的有效性.

     

A GroupTrust model based on service similarity evaluation in P2P networks

The open and anonymous nature of peer‐to‐peer (P2P) networks makes it an ideal medium for attackers to spread malicious contents, which in turn leads to lower quality of network services due to lack of effective trust management mechanism. To improve the quality of services (or transactions), this paper proposes a novel trust and reputation model, named as GroupTrust, based on peer group and evaluation similarity degree in P2P networks. In the proposed model, trust relationships between peers are divided into three categories: trust relationship within a peer group, trust relationship between different groups, and trust relationship between a peer in a peer group with another peer out of this peer group. The model presents the evaluation similarity degree under different context of services and gives local and global reputation computation. Experimental results demonstrate that this model can get more real trust value and deal with the malicious attacks efficiently by comparison with existing models. © 2010 Wiley Periodicals, Inc.     

A secure collaboration service for dynamic virtual organizations

Nowadays, various promising paradigms of distributed computing over the Internet, such as Grids, P2P and Clouds, have emerged for resource sharing and collaboration. To enable resources sharing and collaboration across different domains in an open computing environment, virtual organizations (VOs) often need to be established dynamically. However, the dynamic and autonomous characteristics of participating domains pose great challenges to the security of virtual organizations. In this paper, we propose a secure collaboration service, called PEACE-VO, for dynamic virtual organizations management. The federation approach based on role mapping has extensively been used to build virtual organizations over multiple domains. However, there is a serious issue of potential policy conflicts with this approach, which brings a security threat to the participating domains. To address this issue, we first depict concepts of implicit conflicts and explicit conflicts that may exist in virtual organization collaboration policies. Then, we propose a fully distributed algorithm to detect potential policy conflicts. With this algorithm participating domains do not have to disclose their full local privacy policies, and is able to withhold malicious internal attacks. Finally, we present the system architecture of PEACE-VO and design two protocols for VO management and authorization. PEACE-VO services and protocols have successfully been implemented in the CROWN test bed. Comprehensive experimental study demonstrates that our approach is scalable and efficient.     

A flexible service selection for executing virtual services

With the adoption of a service-oriented paradigm on the Web, many software services are likely to fulfil similar functional needs for end-users. We propose to aggregate functionally equivalent software services within one single virtual service, that is, to associate a functionality, a graphical user interface (GUI), and a set of selection rules. When an end user invokes such a virtual service through its GUI to answer his/her functional need, the software service that best responds to the end-user’s selection policy is selected and executed and the result is then rendered to the end-user through the GUI of the virtual service. A key innovation in this paper is the flexibility of our proposed service selection policy. First, each selection policy can refer to heterogeneous parameters (e.g., service price, end-user location, and QoS). Second, additional parameters can be added to an existing or new policy with little investment. Third, the end users themselves define a selection policy to apply during the selection process, thanks to the GUI element added as part of the virtual service design. This approach was validated though the design, implementation, and testing of an end-to-end architecture, including the implementation of several virtual services and utilizing several software services available today on the Web.     

面向三网融合的Web Service系统架构模型

提出一种面向三网融合的Web Service系统架构模型CWSM（Converged Web Service Model）,目标是允许系统对Web Service做自适应处理,实现其在三个网络中的融合发布;为了克服三个网络带宽的差异性、终端的多样性以及业务特征的差异性,通过设计若干发布控制网关,完成针对WSDL与服务响应内容的融合处理,实现面向三网融合的Web Service系统架构设计。