We report our work on evaluating performance of several MPI Allgather algorithms on Fast Ethernet. These algorithms are ring, recursive doubling, Bruck, and neighbor exchange. The first three algorithms are widely use...
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ISBN:
(纸本)0769524869
We report our work on evaluating performance of several MPI Allgather algorithms on Fast Ethernet. These algorithms are ring, recursive doubling, Bruck, and neighbor exchange. The first three algorithms are widely used today. The neighbor exchange algorithm which was recently proposed by the authors incorporates pair-wise exchange, and is expected to perform better with certain configurations, mainly when using TCP/IP over Ethernet. We tested the four algorithms on terascale Linux clusters DeepComp 6800 and DAWNING 4000A using TCP/IP over Fast Ethernet. Results show that our neighbor exchange algorithm performs the best for long messages, the ring algorithm performs the best for medium-size messages and the recursive doubling algorithm performs the best for short messages.
A platform-independent grid security model and several model-based security policies such as authentication and authorization are presented in this paper. The security policies include the public key infrastructure (P...
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A platform-independent grid security model and several model-based security policies such as authentication and authorization are presented in this paper. The security policies include the public key infrastructure (PKI) management model based on bridge certificate authority (CA), the authentication policy based on virtual organization and the access control policy such as delegation in grid environment. These policies can facilitate authentication among virtual organizations based on different PKI management policies, simplify security authentication in grid environment, and manage grid resources dynamically and effectively.
Web application has some interesting and special characteristics, such as complicated structure and variety of the implementation method, etc. So its model is generally very difficult to be reused. This paper proposes...
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Analog circuits are very important in many high-speed applications. Since the size of analog circuit is becoming larger and more complex, the design is becoming more and more difficult. In this paper, a novel design a...
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After the construction of S-boxes satisfying some good cryptographic properties,the ByteSub step in Rijndael algorithm was improved based on the dynamical selection of S-boxes depending on the round *** improved algor...
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After the construction of S-boxes satisfying some good cryptographic properties,the ByteSub step in Rijndael algorithm was improved based on the dynamical selection of S-boxes depending on the round *** improved algorithm has been proved to have stronger ability to resist differential ***,the avalanche probability of this algorithm is more reasonable and the design method is a challenge to the Kerckhoff hypothesis.
To solve the security issues in a mobile agent system, the access control is always employed. Existing access control models enable the agent's identity, trust and other information to influence the security decis...
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ISBN:
(纸本)0769523285
To solve the security issues in a mobile agent system, the access control is always employed. Existing access control models enable the agent's identity, trust and other information to influence the security decisions. We argue that the path, which a mobile agent travels along, should be taken into consideration and affect what the agent can do dynamically. An access control model is proposed in this paper which captures the path history of the agent and reaches a decision according to both whether the path matches a path pattern set and whether the path can follow a host patch set. The flexibility of this model is shown and some issues in implementing such a model are discussed as well.
This paper describes a new approach for on-line multi-stroke sketch recognition. The approach is based on hidden Markov model (HMM). Sketches are modeled to HMM chains, and strokes are mapped to different HMM states. ...
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This paper describes a new approach for on-line multi-stroke sketch recognition. The approach is based on hidden Markov model (HMM). Sketches are modeled to HMM chains, and strokes are mapped to different HMM states. The proposed approach introduces a new method to determine HMM state-number, based on which an adaptive HMM sketch recognizer is constructed. A combined feature based on curvature, velocity and geometrical character of stroke for sketch recognition is also proposed to improve recognition accuracy. Finally, the experiments prove the effectiveness and efficiency of the proposed approach.
While feature selection is very difficult for high dimensional, unstructured data such as face image, it may be much easier to do if the data can be faithfully transformed into lower dimensional space. In this paper, ...
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Many structured P2P systems use DHT technologies to map data items onto the nodes in various ways for scalable routing and location. Most of the systems require O(logn) hops per lookup request with O(logn) neighbors p...
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Many structured P2P systems use DHT technologies to map data items onto the nodes in various ways for scalable routing and location. Most of the systems require O(logn) hops per lookup request with O(logn) neighbors per node, where n is the network size. This paper presents a constant-degree P2P architecture, namely Cycloid, which emulates a Cube Connected Cycles (CCC) graph in the routing of lookup requests. It achieves a time complexity of O(d) per lookup request by using O(1) neighbors per node, where n = d × 2d. Authors compare Cycloid with other two constant-degree systems, Viceroy and Koorde, in various architectural aspects via simulation. The simulation shows that Cycloid has more advantages for large scale and dynamic systems that have frequent node arrivals and departures. In particular, Cycloid delivers a higher location efficiency in the average case and exhibits a more balanced distribution of keys and query loads between the nodes.
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