We propose a new scheme for peer-to-peer live media streaming that uses network coding. this scheme includes the grouping method of media data on the server side, the network coding and decoding polices on each peer n...
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ISBN:
(纸本)9780769526942
We propose a new scheme for peer-to-peer live media streaming that uses network coding. this scheme includes the grouping method of media data on the server side, the network coding and decoding polices on each peer node and the packet scheduling algorithm with multiple suppliers. Unlike other related scheme based on network coding, our scheme does not require any centralized knowledge of the network topology and nodes make decisions of how to propagate blocks of streaming data based only on local information. Simulation results show that under the same network conditions, our proposed scheme can decrease the average playback startup delays of peer nodes, or can improve the average playback qualities of peer nodes with predefined playback startup delay than that not using network coding at all.
A Grid portal is a user's access point to Grid systems. A disadvantage existing in current Grid Portals is that they are usually designed for specific applications and difficult to adapt to new applications. Portl...
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ISBN:
(纸本)0769526950
A Grid portal is a user's access point to Grid systems. A disadvantage existing in current Grid Portals is that they are usually designed for specific applications and difficult to adapt to new applications. Portlets are Java based web components, which makes a portal more flexible and can be easily reused. Grid systems have some common services, and these services are independent from each other somewhat. In this paper, we propose a portlet-based Grid portal architecture by encapsulating one or more Grid services to a portlet. this architecture enables a user to configure a Gridportal environment that suits him best and improves the reusability of the Gridportal. A portlet-based Grid portal prototype is implemented to evaluate the usefulness and effectiveness of the architecture.
An important challenge regarding peer's trust valuation in P2P systems is how to cope with strategically altering behaviors of malicious peers efficiently. However, the trust metrics employed by the existing syste...
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ISBN:
(纸本)0769526950
An important challenge regarding peer's trust valuation in P2P systems is how to cope with strategically altering behaviors of malicious peers efficiently. However, the trust metrics employed by the existing systems do not provide adequate support to track this dynamics and impact dynamic adaptability of trust valuation. In this paper, we propose an adaptive peer-to-peer dynamic trust metric. Considering the dynamics of trust which relates to the evolution of trust in time and in the face of new experiences, we introduce an adaptive forgetting scheme, where the forgetting factor is adjusted in time to reflect quick changes of peers' behavior. thus, the trust evaluation has better adaptability to the dynamic of trust. theoretic analysis and simulation show that, comparing with existing trust metric, our metric has advantages of adaptability on modeling dynamic trust and is highly effective in countering malicious peers regarding strategic altering behavior.
Workflow management technologies play a very important role in constructing grid application environment by automating service composition and execution. Withthe fast spread of grid technology, workflow management sy...
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ISBN:
(纸本)9780769526942
Workflow management technologies play a very important role in constructing grid application environment by automating service composition and execution. Withthe fast spread of grid technology, workflow management system should be flexible to meet increasing requirements of service composition. this paper introduces a distributed workflow management approach DWM4CGSP named distributed Workflow Management for CGSP, which can improve capability of workflow execution by dynamically assimilating new workflow engines and balancing workload among these engines. Moreover dynamic load balancing is applied in DWM4CGSP in order to make workload on each engine at reasonable level. Finally an implementation demonstrates that DWM4CGSP works well in CGSP and can be further extended to other similar grids.
In this paper, we investigate several data reduction schemes to improve the computational efficiency in the multi reference configuration interaction (MR-CI) method, one of the main quantum chemical approaches for sol...
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ISBN:
(纸本)3540319948
In this paper, we investigate several data reduction schemes to improve the computational efficiency in the multi reference configuration interaction (MR-CI) method, one of the main quantum chemical approaches for solving the electronic Schrodinger equation. the basic idea is to take advantage of the often relatively low accuracy requirements on the solution of the resulting large eigenvalue problem, whose dimension may reach several hundred millions or even more. We will discuss some approaches to reduce the amount of data to be accessed and to be transferred within the Davidson subspace diagonalization method. We also show experimental results achieved withthe COLUMBUS code.
Virtual Environments using haptic devices have proved useful for assembly/disassembly simulation of mechanical components. To date most haptic virtual environments are stand-alone. Collaborative Haptic Virtual Environ...
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ISBN:
(纸本)0769526977
Virtual Environments using haptic devices have proved useful for assembly/disassembly simulation of mechanical components. To date most haptic virtual environments are stand-alone. Collaborative Haptic Virtual Environments (CHVEs) are distributed across a number of users via a network, such as the Internet. these present new challenges to the designer, such as consistency of the virtual environments, user user haptic interaction, and scalability. the system described in this paper considers the CHVEs to be distributed over a packet-switched network such as the Internet. It gives priority to the validation of interactions between objects grasped by users;guarantees consistency across different user's virtual environments. the paper explains the components used and the consistency-maintenance scheme that guarantees the consistency of the virtual scene in the remote nodes. Consistency and force feedback results are also discussed. Results presented show the system maintains a consistent and satisfactory response when network incurs delay or packet jitter.
In BitTorrent system, HAVE, REQUEST and PIECE messages are the main transmission parts among peers. To improve the efficiency of network transmission and reduce the management cost of file delivery, a new scheme is pr...
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ISBN:
(纸本)0769526950
In BitTorrent system, HAVE, REQUEST and PIECE messages are the main transmission parts among peers. To improve the efficiency of network transmission and reduce the management cost of file delivery, a new scheme is proposed to improve HAVE message-MultiHave message. Withthe high bandwidth and consistent peers, together withthe application of the timer, the frequency ratio of sending HAVE message to that of sending MultiHave message is 100, while the flow ratio of sending MultiHAVE message to that of sending MultiHave message is 11.01. In contrast to HAVE message, MultiHave has sharply reduced the volume and flow of messages, and it can efficiently prevent the HAVE storm in the original mechanism and reduce the management costs. At the same time, when the action of network peers is diverse, it can also return to the original HAVE message in some peers and doesn't affect the performance of BT system.
Gnutella-like unstructured systems usually use flooding with a high number of TTL hops to probe as many peers as possible within a short period of time. However, this mechanism is very inefficient because it handles a...
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GRID computing is a more and more attractive approach. Its aim is to gather and to share the resources of a network like the content, the storage or CPU cycles. A computational distributed system like SETI@home produc...
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ISBN:
(纸本)3540339736
GRID computing is a more and more attractive approach. Its aim is to gather and to share the resources of a network like the content, the storage or CPU cycles. A computational distributed system like SETI@home produces a power up to 70 TFlops whereas the current best parallel supercomputer BlueGene produces a power of 140 TFlops. Such a supercomputer costs very much contrary to a system like SETI@home. But the use of many computers to increase the global computational power involves several communication problems. We must maintain the GRID communication in order to make any type of computation even though the network is volatile. In this paper, we present a model to represent GRID applications and networks in order to show faults impacts. We present a fully distributed solution based on a random walk to manage the topology of the GRID. No virtual structure needs to be maintained and this solution works on asynchronous networks. We also present some simulations of our solution.
All resources of grid systems are connected by network and Ethernet-based TCP/IP is a widely used network in the grid systems. the TCP/IP is processed on a host CPU in computer systems and this imposes heavy loads on ...
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ISBN:
(纸本)9780769526942
All resources of grid systems are connected by network and Ethernet-based TCP/IP is a widely used network in the grid systems. the TCP/IP is processed on a host CPU in computer systems and this imposes heavy loads on the host CPU. Recently TCP/IP Offload Engine (TOE) technology, which processes TCP/IP on a network adapter instead of the host CPU, has become an important approach to this problem. To adopt the TOE to computer systems successfully, it is necessary to develop a kernel module supporting the TOE. the TOE kernel module should provide the binary compatibility for the BSD socket interface, which is widely used in the most network programming, and support both of the TOE and the Ethernet-based NIC simultaneously. this paper proposes a TOE kernel module satisfying these requirements in the Linux systems. Experimental results also show that the TOE kernel module imposes little load on the host CPU.
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