基于动态扫描周期的多属性垂直切换算法

当终端处于动态的异构无线网络环境下,为在减少终端能耗的同时,及时检测到周围可用的无线网络并从中快速选择一个合适的接入网络,提出一种基于动态扫描周期的多属性垂直切换算法。在网络发现阶段根据终端接收到的当前接入网信号强度和终端的移动速度动态调整扫描周期,减少终端接口激活次数。在网络选择阶段采用多属性判决法综合考虑多种网络属性,采用层次分析法和熵权法根据业务类型不同对各参考属性进行权值分配,引入微小阈值对网络进行过滤。仿真结果表明,与现有算法相比,所提算法能够在减少终端能耗的同时,及时地为终端选择出最佳的接入网络。     

A unified framework for consistency check

Constraint Satisfaction Problem (CSP) involves finding values for variables to satisfy a set of constraints. Consistency check is the key technique in solving this class of problems. Past research has developed many algorithms for such a purpose, e.g., node consistency, are consistency, generalized node and arc consistency, specific methods for checking specific constraints, etc. In this article, an attempt is made to unify these algorithms into a common framework. This framework consists of two parts. the first part is a generic consistency check algorithm, which allows and encourages each individual constraint to be checked by its specific consistency methods. Such an approach provides a direct way of practical implementation of the CSP model for real problem-solving. the second part is a general schema for describing the handling of each type of constraint. the schema characterizes various issues of constraint handling in constraint satisfaction, and provides a common language for expressing, discussing, and exchanging constraint handling techniques. © 1995 John Wiley & Sons, Inc.     

A MIH-based approach for best network selection in heterogeneous wireless networks

In the next generation wireless networks, different technologies belonging to one or more operators should be integrated to form a heterogeneous environment based on an IP core network infrastructure. This ensures user mobility and service continuity by maintaining connections when switching between various technologies and it introduces new resources and possibilities for applications. In this context, an automatic interface selection based on instantaneous and practical constraints and user preferences (Quality of Service (QoS) parameters, available resources, security, power consumption, etc.) is therefore required. The different network selection and handover schemes proposed in the literature can be classified into three approaches according to who is responsible for making the handover decision: the terminal, the network or by a cooperation between both of them. However, these approaches keep presenting some drawbacks; namely the problem of resources management and network load balancing whenever the selection is controlled by the mobile terminal (MT) and the problem of scalability and unknown operator's management policy whenever the selection is rather controlled by the network.In this article, first we propose a MIH based approach for handover initiation and preparation for heterogeneous wireless network. The proposed framework is based on the principals of IEEE 802.21 for context information gathering and optimized handover decision making. Second, we propose a new architecture and new network selection scheme that explicitly take into account the current resource usage and the user preferences. Furthermore, our solution ensures the selection of the most suitable network for each flow while taking into consideration its expectations in terms of QoS. A feasibility study of implementing a new architecture on a single MT is evaluated by using typical scenarios and using various algorithms. Thanks to the introduced function entities and modules in the proposed architecture, network utilization balancing and user and application expectations, which are successfully assured without operator intervention. Performance analysis shows that the proposed algorithm best meets the common quality requirements.     

A new flow-based fast handover method for Mobile IPv6 network with route optimization

Flow-based fast handover method is designed for Mobile IPv6 network. The FFHMIPv6 uses the flow state information to redirect the traffic flow to a new location. This makes it possible that the reception of packets simultaneously with the BU registration process, thus minimizing the delay experienced in the handover. But it does not consider the route optimization. In this paper, a new flow-based fast handover method is proposed which enhanced the existing flow-based fast handover method to support route optimization. The analysis shows that this scheme has a better performance than the existing FFHMIPv6 scheme.     

A survey of vertical handover decision algorithms in Fourth Generation heterogeneous wireless networks

Vertical handover decision (VHD) algorithms are essential components of the architecture of the forthcoming Fourth Generation (4G) heterogeneous wireless networks. These algorithms need to be designed to provide the required Quality of Service (QoS) to a wide range of applications while allowing seamless roaming among a multitude of access network technologies. In this paper, we present a comprehensive survey of the VHD algorithms designed to satisfy these requirements. To offer a systematic comparison, we categorize the algorithms into four groups based on the main handover decision criterion used. Also, to evaluate tradeoffs between their complexity of implementation and efficiency, we discuss three representative VHD algorithms in each group.     

A comparison of scanning methods and the vertical control implications for scanning probe microscopy

This article compares the imaging performance of non‐traditional scanning patterns for scanning probe microscopy including sinusoidal raster, spiral, and Lissajous patterns. The metrics under consideration include the probe velocity, scanning frequency, and required sampling rate. The probe velocity is investigated in detail as this quantity is proportional to the required bandwidth of the vertical feedback loop and has a major impact on image quality. By considering a sample with an impulsive Fourier transform, the effect of scanning trajectories on imaging quality can be observed and quantified. The non‐linear trajectories are found to spread the topography signal bandwidth which has important implications for both low and high‐speed imaging. These effects are studied analytically and demonstrated experimentally with a periodic calibration grating.     

A predictive handover scheme to improve service quality in the IEEE 802.21 network

The Media Independent Handover (MIH) standard defined in the IEEE 802.21 specification supports vertical handovers across heterogeneous networks. A cross-layer scheduling scheme is proposed to exploit Link Going Down information from MIH to predict handover requirements, and then improve the performance of Quality of Service (QoS) enabled transport services given the limited radio spectrum available for handovers in a heterogeneous network environment. According to simulation results, the proposed scheme can effectively increase the effective range of QoS sensitive services at the cell border while executing the handover procedure.     

一种基于标地分离的卫星网络移动切换管理技术

移动卫星网络因具有覆盖区域广、通信延时低等优势受到广泛关注,当前有大量研究旨在开发IP协议的组网技术,并将其与地面IP网络融合。融合网络的挑战之一,即为卫星移动性,用户在卫星网络中的接入点频繁切换导致移动管理问题,而现有的移动IP技术不能高效支持卫星网络移动切换。为了高效支持移动切换,在卫星网络中应用标地分离思想,在标地分离的架构下研究切换管理问题;用映射服务系统对终端进行位置管理,在移动切换中由新接入卫星网关和终端的标志为主要信息在原卫星中形成通告转发表。仿真结果表明,相对移动IP技术,该方法有明显优势。将其应用于卫星网络时可以降低切换延时,减少大量的绑定更新开销或是次优路由,提升系统的性能和可扩展性。     

A new characterization of the set of all intervals,based on the necessity to check consistency easily

The purpose of this paper is to present a new characterization of the set of all intervals. This characterization is based on several natural properies useful in mathematical modeling; the main of these properties is the necessity to easily check consistency of incompletes knowledge. This characterization is obtained both for one-dimensional and for multidimensional cases.     

A journey through the DQDB network literature

The Distributed Queue Dual Bus (DQDB) network has been adopted as the subnetwork for the IEEE 802.6 metropolitan area network (MAN) standard. Since its original proposition a few years back, DQDB has attracted significant attention because of the simplicity of its medium access control (MAC) protocol. The intense scrutiny that DQDB has been subjected to has lead to the identification of a number of its potential problems, and a number of “add-on” strategies have been proposed to “fix” such problems. Moreover, a number of architectural variations have also been proposed to improve the network behavior. Since there has been a literature explosion on DQDB over the past few years, this article is intended to extract the significant features of various DQDB-based investigations, and to present them in an unified manner.     

A new electronic check system with reusable refunds

This paper presents a new online check system that solves the reusability problem of refunds in existing systems using the partially blind signature. The clear part of the signature is used to encode the face value of a check. In our system, refunds can be reused in payment in the same way as withdrawn checks without any limitation. We also use a one-time secret key as the serial number of a check to increase the efficiency of payment. The new system provides multiple offline shopping sessions to minimize the number of online messages. During the offline session, we use a one-way accumulator to construct a proof of payment. The security and the atomicity of the system is also discussed. Published online: 3 September 2002     

A Chilean seismic regionalization through a Kohonen neural network

Through this paper we are presenting a study of seismic regionalization for continental Chile based on a neural network. A scenario with six seismic regions is obtained, irrespective of the size of the neighborhood or the range of the correlation between the cells of the grid. Unlike conventional seismic methods, our work manages to generate seismic regions tectonically valid from sparse and non-redundant information, which shows that the self-organizing maps are a valuable tool in seismology. The high correlation between the spatial distribution of the seismic zones and geological data confirms that the fields chosen for structuring the training vectors were the most appropriate.     

A CSP approach for the network of product lifecycle constraints consistency in a collaborative design context

In this paper, we are considering that the design process can be modelled in the form of a constraint satisfaction problem (CSP). CSP modelling or resolution has proved its efficiency within the framework of single-designer design. We propose to extend the functions of CSP to the context of multi-concept design of the same artefact. We define CoCSP as cooperative constraint satisfaction problem including the actors of the design problem. We are presenting the operating principles of an algorithm for the real-time management of design decisions, based on a model described in the form of a CoCSP for the integration of supply-chain constraints. This algorithm enables the number of design decisions rejected at a given moment in design to be kept to a minimum. The algorithm forms the core of a prototype for an unsupervised, generic constraint-based collaborative design system. Our aim is to produce a platform centred on the notion of constraints that will enable a product design problem to be modelled and solved by integrating supply-chain constraints as far upstream as possible.     

包含协议和语义的构件一致性验证方法

在基于构件的系统设计中,需要对构件的一致性进行验证。构件的一致性包括语义一致性和协议一致性,已有的一致性验证方法仅支持构件的协议一致性验证。而在实际应用中除了要进行构件的协议一致性验证外,还需要进行其语义一致性验证。为此提出了一种包含协议和语义的构件一致性验证方法。所提方法将方法语义与基于场景的需求规约相结合,使用语义扩展接口自动机模型(SIA)来建模构件的语义和协议信息,使用带有语义约束的UML交互概观图来表示基于场景的需求规约。通过对SIA和带语义约束的UML交互概观图的行为的理论分析,进一步形成了一种一致性验证算法,并用实例来说明其过程。该算法不仅能够检验系统中构件的协议一致性,而且能够检验其语义一致性。该算法中的方法语义包括了该方法参数的类型和详细语义信息,更符合实际应用情形。     

蓝牙在微微网间的一种数据通讯方法

采用蓝牙技术，结合1至14点蓝牙无线数据传输单元的具体应用特点，文章提出了一种新型的蓝牙在微微网间通过主机控制器进行数据交换的方法，给出了硬件的构成及通讯时序图。     

一种基于约束格维护概念模型一致性的方法

针对以形式概念分析理论为基础的概念建模过程中知识表示存在差距的问题,提出一种整合专家知识到概念格结构中的形式化模型.首先,将一组属性依赖与概念格提供的一系列蕴涵对齐,对原始格进行修订,然后,通过使用外延投影建立约束格来提供变化轨迹,并在此基础上,提出基于形式概念分析约束格理论弥补这一差距的建模方法,以维护概念模型的一致性.该方法不仅提供了领域专家修订概念模型的途径,还保留了原始格和最终约束格之间的变化轨迹.通过这些变化,专家可以访问实践中的概念如何与数据自动发布的概念相关联.最后,结合示例对基于约束格维护概念模型一致性方法的有效性进行了验证.     

A multimedia healthcare data sharing approach through cloud-based body area network

Wireless Body Area Network (WBAN), as a dramatic platform for pervasive computing and communication, has been widely applied in healthcare domains. Since the patient-related data in the form of text, image, voice, etc. is significant in the process of healthcare services, efficiently managing these media data from various WBAN is vital for various applications. Recently, Cloud-assisted WBAN has become popular that can supply massive computing, flexible storage and various software services to WBAN. Still, there are some challenging issues exist in this platform to deliver and share the huge media healthcare data to remote terminals timely with guaranteed QoS support. In the paper, we propose an efficient network model that combines WBAN and Cloud for valid data sharing. The proposed network architecture is designed as four layers: perception layer, network layer, cloud computing layer, and application layer. In the network, the integration of TCP/IP and Zigbee in the coordinator devices is utilized. Consequently, WBAN coordinators can compatibility inter-operate with various local networks such as WiFi and LTE network to support high mobility of users. Besides, we integrate Content Centric Networking (CCN) with our proposed architecture to improve the ability of the WBAN coordinator. Thus, it can support uninterrupted media healthcare content delivery. In addition, adaptive streaming technique was also utilized to reduce packet loss. Various simulations were conducted using OPNET simulator to show the feasibility of the proposed architecture in terms of transmitting a huge amount of media healthcare data in real-time under traditional IP-based network.     

A hybrid approach to concept selection through fuzzy analytic network process

Evaluating conceptual design alternatives in a new product development (NPD) environment has been one of the most critical issues for many companies which try to survive in the fast-growing world markets. Therefore, most companies have used various methods to successfully carry out this difficult and time-consuming evaluation process. Of these methods, analytic hierarchy process (AHP) has been widely used in multiple-criteria decision-making (MCDM) problems. But, in this study, we used analytical network process (ANP), a more general form of AHP, instead of AHP due to the fact that AHP cannot accommodate the variety of interactions, dependencies and feedback between higher and lower level elements. Furthermore, in some cases, due to the vagueness and uncertainty on the judgments of a decision-maker, the crisp pairwise comparison in the conventional ANP is insufficient and imprecise to capture the right judgments of the decision-maker. Therefore, a fuzzy logic is introduced in the pairwise comparison of ANP to make up for this deficiency in the conventional ANP, and is called as fuzzy ANP. In short, in this paper, a fuzzy ANP-based approach is proposed to evaluate a set of conceptual design alternatives developed in a NPD environment in order to reach to the best one satisfying both the needs and expectations of customers, and the engineering specifications of company. In addition, a numerical example is presented to illustrate the proposed approach.     

Design and fabrication of a resonant scanning micromirror suspended by V shaped beams with vertical electrostatic comb drives

A scanning micromirror suspended by a pair of V-shaped beams with vertical electrostatic comb drives was designed, modeled, fabricated and characterized. The dynamic analyses were carried out by both theory calculation and FEM simulation to obtain frequency response, stiffness characteristics, oscillation modes and their resonance frequencies. The device was fabricated using the silicon-on-insulator process by only two photolithography masks. Some problems during the process such as the micromirror distortion and the side sticking of the comb fingers were effectively solved by thermal annealing and alcohol-replacement methods, respectively. Based on the fabricated device, the typical scanning patterns for 1-D and 2-D operation were obtained. The experimental results reveal that the micromirror can work in resonant mode with the resonant frequency of 2.38 kHz. The maximum deflection angles can reach ±4.8°, corresponding to a total optical scanning range of 19.2° at a driving voltage of 21 V.     

The mechanism through which members with reconstructed identities become satisfied with a social network community: A contingency model

This study investigates members’ satisfaction with interest-based social network communities from an identity-reconstruction perspective. Drawing upon the self-discrepancy theory and the regulatory focus theory, we theoretically modeled the factors (relating to identity reconstruction) that influence members’ satisfaction with social network communities and further investigated whether these influences on satisfaction are contingent upon how much the virtual identity is reconstructed. Data (n = 1063) were collected from six interest-based social network communities. Results support most main effects and further support two moderating effects. The effect of bridging social capital on satisfaction and the effect of privacy concern on satisfaction are contingent upon identity reconstruction.