There are the trends that the users hope to retrieve information among lots of individual database systems distributed in lots of virtual organizations. To connect all these individual database systems into a virtual ...
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There are the trends that the users hope to retrieve information among lots of individual database systems distributed in lots of virtual organizations. To connect all these individual database systems into a virtual database system is a significant issue. This paper presents VIRGO_DDBMS, a framework of distributed database system based on virtual hierarchical tree Grid organizationsfVIRGO) P2P network. The table space are classified as hierarchical domains like DNS. The servers hosting database systems joins several groups of VIRGO network according to the owned tables' domains. VIRGO_DDBMS is effective for data update and retrieve by using distributed SQL statements. We use the policies which cache the host machines' addresses of database systems to avoid the overload of traffic of root nodes in tree structure. The proposal presented here can construct a virtual distributed database system which can manages huge volumes of data by connecting all database systems together which are owned by the individual virtual organizations.
In this paper, we investigate distributed relay selection in OFDM-based cooperative wireless networks. A selective Decode-and-Forward relaying strategy is adopted, in which one relay is selected to forward the entire ...
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In this paper, we investigate distributed relay selection in OFDM-based cooperative wireless networks. A selective Decode-and-Forward relaying strategy is adopted, in which one relay is selected to forward the entire OFDM symbol. Theoretical outage performance is analyzed and evaluated first. Then six relay selection schemes based on different selection criteria are given. The outage performance of one of the schemes coincides with the theoretical value and all the schemes need only local CSI and can thus be implemented in a distributed way. Monte Carlo simulations validate our analysis and show that significant performance gain can be obtained compared to that of direct transmission.
This paper presents a spectrally efficient distributed coded cooperation based on Opportunistic Relaying for multi-relay. The proposed scheme chooses the best relay to participate in the cooperation depending on the i...
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This paper presents a spectrally efficient distributed coded cooperation based on Opportunistic Relaying for multi-relay. The proposed scheme chooses the best relay to participate in the cooperation depending on the instantaneous channel information. We adopt distributed Rate-compatible punctured convolutional code. The relay operates on DF mode. After the single relay has been chosen, the best relay will cooperate with the source to transmit the codeword. Thus, the proposed scheme only use two orthogonal subchannels to finish the second part of the codeword. And the spectrum efficiency is greatly improved. Theoretical analysis and simulation results show that, compared with multi-relay coded cooperation scheme, the new scheme can achieve the same performance with low coding and decoding complexity and high spectrum efficiency.
Cognitive radio has the potential to resolve the paradox of limited available radio resources and underutilization spectrum usage by opportunistically exploiting idle frequency. Opportunity identification and exploita...
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Cognitive radio has the potential to resolve the paradox of limited available radio resources and underutilization spectrum usage by opportunistically exploiting idle frequency. Opportunity identification and exploitation are the most challenging issues due to the spectrum opportunities varied in both temporal and spatial domains. We focus on distributed methods of opportunity spectrum access based on local policies which are more feasible in available networks. In this article we first present the general system model in cognitive network, following with the listed utility functions. An overview of distributed OSA approaches is then provided. Finally, we conclude the related issues for future research.
Current CAD/CAE systems are not ideal for engineering design in distributed heterogeneous design resources. This paper investigates the approach and mechanism of distributed design resources integration and binding in...
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Current CAD/CAE systems are not ideal for engineering design in distributed heterogeneous design resources. This paper investigates the approach and mechanism of distributed design resources integration and binding in collaborative design process based on serviceoriented architecture. Service-ORiented computing EnviRonment (SORCER) is employed to build a highly flexible distributed network components environmentdesign service space. A SORCER Based Collaborative Design Environment is presented. As the key modules of the system, Design activity modeling, Design interface, design contest and design process graph is introduced in detail. Design Behavior Matrices is designed as the binding mechanism to drive distributed design resources integration process during the design tasks execution time. At last, this paper introduces a engineering layout design to demonstrate the mechanism and the system. This system aims to enable asynchronous distributed collaborative design with ease of alternative design services, reduced design cycles, and improved design resolution quality.
distributed resource monitoring system is the core component of grid platforms, and also a key technology to grid application development. However, most of the traditional monitoring systems, either single centralized...
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distributed resource monitoring system is the core component of grid platforms, and also a key technology to grid application development. However, most of the traditional monitoring systems, either single centralized or hierarchical, have significant limitations in scalability, extensibility and faulttolerance. Based on GMA (Grid Monitoring Architecture), Coequal Multi-Monitoring Technique (CMMT) was proposed. The mechanisms and implementation of coequal monitor management, coequal monitoring and coequal monitor cooperation were discussed. Preliminary experimental results showed that system above is scalable and extensible to overcome the problems within the grid monitoring system.
Cloud computing has become a popular computing paradigm in which virtualized and scalable resources are consolidated to provide services over Internet. However, the resource capability of a single cloud is generally l...
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ISBN:
(纸本)9781424474226;9780769540887
Cloud computing has become a popular computing paradigm in which virtualized and scalable resources are consolidated to provide services over Internet. However, the resource capability of a single cloud is generally limited, and some applications often require various cloud centers over Internet to deliver services together. Therefore, a Virtual Organization (VO) will be a promising approach to integrate services and users across multiple autonomous clouds. However, how to build a secure virtual organization to achieve the collaboration goals is a critical problem, and some issues such as membership agreement, policy conflict and trust management should be adequately addressed. In this paper, we present a framework CloudVO which based on security policies and trust management techniques to provide some flexible and dynamic VO management protocols for clouds. Therefore, CloudVO can achieve inter-cloud collaboration without destroying a cloud's local policies. Based on previous VO security management experiences, we have conducted some preliminary simulations to verify the effectiveness our approaches for cloud computing environments.
The spatial relations representation modeling is a basic task of computer graphics comprehension, however, previous modeling is usually aimed at a certain kind of relations such as direction, topology and distance. Th...
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ISBN:
(纸本)9781424474226;9780769540887
The spatial relations representation modeling is a basic task of computer graphics comprehension, however, previous modeling is usually aimed at a certain kind of relations such as direction, topology and distance. The models are relatively independent and inconsistent with human's cognitive logic, thus building a unified spatial relations representation modeling based on different reference frames is required. In this paper we first discuss the importance of a reference frame for building a spatial relations representation modeling, then introduce the feasibility of histogram modeling for building a unified spatial relations representation modeling, and then describe the construction of spatial relations representation modeling based on visual area histogram under the deictic reference frame, in order to testify the correctness of the modeling, two typical examples are given, finally point out the advantages of this modeling, as well as the future work.
The publish-subscribe (pub-sub) paradigm is maturing and integrating into community-oriented collaborative applications. Because of this, pub-sub systems are faced with an event stream that may potentially contain lar...
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With the development of network technology and the extensive use of e-commerce, the traditional e-commerce processes and its supported technology were faced with challenges. As a new distributedcomputing model, Mobil...
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ISBN:
(纸本)9781424451623;9781424451616
With the development of network technology and the extensive use of e-commerce, the traditional e-commerce processes and its supported technology were faced with challenges. As a new distributedcomputing model, Mobile Agent technology has many personal advantages and features such as reducing network load, without continuous network connections and easy to support services, having been hailed as the next generation of network computing note by many scholars. However, the mobility of Mobile Agent brings a lot of uncertainty, in order to enable Mobile Agent successfully applied to e-commerce, we must solve the Mobile Agent's security issues. Mobile Agent System based on the analysis of security issues, proposes a mobile agent-based security policy based on trusted third party, on this basis, builds e-commerce security model.
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