To understand and predict electromagnetic behavior is one of the most important electrical engineering technologies. FDTD is the key algorithm for solving this kind of problems, which provides a direct, time domain so...
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To understand and predict electromagnetic behavior is one of the most important electrical engineering technologies. FDTD is the key algorithm for solving this kind of problems, which provides a direct, time domain solution to Maxwell's equations in differential form with relatively good accuracy and flexibility. In this paper, we propose a novel hybrid parallelization model for FDTD method, which combines the domain distribution scheme and the single instruction multiple data (SIMD) parallelization. This model is able to exploit the computing potential of a new generation parallel machine named cell broadband engine (CBE). The experiment results show that the algorithm obtains approximately linearly speedup with respect to the number of SPEs and has excellent scalability.
During the study of grid projects, a real grid environment or simulated grid is built up for development and experiment normally. But there are some disadvantages such as high cost, complex deployment and configuratio...
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During the study of grid projects, a real grid environment or simulated grid is built up for development and experiment normally. But there are some disadvantages such as high cost, complex deployment and configuration, hard management, even conflict among people. A novel virtual grid experiment method with HAL (Hardware Abstraction Level) virtualization technology is presented, which can conquer the disadvantages above and has been used in MedImgrid for the development of medical grid applications. The experiment shows that the method is feasible with low cost, easy configuration and convenient management, so as to increase research efficiency and shorten developing cycle. Furthermore, it can be applied not only in MedImgrid but also in some other grid projects.
This paper proposes a novel parallel data transfer mechanism to improve the performance of data transfer in grid environment. It utilizes the servers distributed in grid system and selects some of them as the proxy se...
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This paper proposes a novel parallel data transfer mechanism to improve the performance of data transfer in grid environment. It utilizes the servers distributed in grid system and selects some of them as the proxy servers. It introduces the method of how to select the proxy server. Then data are divided into several parts and sent through the selected proxy servers with different physical links. By that, it can effectively improve the performance of data transfer.
In gridcomputing, group communication is an important strategy to realize large-scale information resource sharing. However, it is very difficult to ensure the security of group communication in large-scale grid envi...
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In gridcomputing, group communication is an important strategy to realize large-scale information resource sharing. However, it is very difficult to ensure the security of group communication in large-scale grid environment. In this paper, based on the basic theories of threshold signature and the basic characteristics of group communication in grid, we present four algorithms, including keys generating, individual signature generating and verifying, group signature generating and encrypting, decrypting and group signature verifying, which constitute the authenticated encryption mechanism for group communication in grid. Finally, we validate the correctness of the authenticated encryption mechanism proposed in this paper and analyze its security. In addition, the validity of this mechanism is verified by the experiments. The results show that it is efficient to ensure the security of group communication in grid.
Automated trust negotiation (ATN) is an important means to establish trust between strangers through the exchange of digital credentials and mobile access control policies specifying what combinations of credentials a...
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ISBN:
(纸本)9781424414895
Automated trust negotiation (ATN) is an important means to establish trust between strangers through the exchange of digital credentials and mobile access control policies specifying what combinations of credentials a stranger must submit. As a certificate may contain sensitive information, unlimited disclosure will leak valuable information or jeopardize individual privacy. In order to prevent information leakage, the negotiation protocol is designed so complicated that a requestor is hard to attain the access. In addition, if the encryption algorithm is short in security intensity, the transmitting message over the public channel is easy to be attacked. To solve these problems, an asymmetrical encryption based ATN model (AEBM) is proposed in this paper. AEBM adopts credentials with a flexible format to meet the requirements of access control policies, instead of disclosing the whole contents of a certificate. Further, AEBM uses asymmetric encryption technique to encrypt the transmitting message, which can prevent information from leaking. AEBM presents a new negotiation strategy to enhance the negotiation efficiency. A use case is studied to prove that AEBM is sound and reasonable.
Text categorization is the process of assigning documents to a set of previously fixed categories. It is widely used in many data-oriented management applications. Many popular algorithms for text categorization have ...
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ISBN:
(纸本)9780769533162
Text categorization is the process of assigning documents to a set of previously fixed categories. It is widely used in many data-oriented management applications. Many popular algorithms for text categorization have been proposed, such as Naive Bayes, k-Nearest Neighbor (k-NN), Support Vector Machine (SVM). However, those classification approaches do not perform well in every case, for example, SVM can not identify categories of documents correctly when the texts are in cross zones of multi-categories, k-NN cannot effectively solve the problem of overlapped categories borders. In this paper, we propose an approach named as Multi-class SVM-kNN (MSVM-kNN) which is the combination of SVM and k-NN. In the approach, SVM is first used to identify category borders, then k-NN classifies documents among borders. MSVM-kNN can overcome the shortcomings of SVM and k-NN and improve the performance of multi-class text classification. The experimental results show MSVM-kNN performs better than SVM or kNN.
It is very significant for the medical and health enterprises to develop an efficient medical information grid to achieve sufficient medical data share and integration. In order to access heterogeneous data resources ...
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It is very significant for the medical and health enterprises to develop an efficient medical information grid to achieve sufficient medical data share and integration. In order to access heterogeneous data resources transparently, front agent is built on heterogeneous databases or medical systems, the same as the unified data models and mapping rules with grid services to communicate with upper grid middleware, so that users can query or access medical data conveniently. Two medical application instances, medical information integration and content-based image diagnosis or retrieval of emphysema disease, are introduced and realized with these technologies.
Cell broadband engine (Cell BE) is a state-of-the-art heterogeneous multi-core processor. It is an accelerator-based multi-core architecture, which contains a powerful 64-bit dual-threaded PowerPC core and eight high ...
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ISBN:
(纸本)9780769533063
Cell broadband engine (Cell BE) is a state-of-the-art heterogeneous multi-core processor. It is an accelerator-based multi-core architecture, which contains a powerful 64-bit dual-threaded PowerPC core and eight high efficient single-instruction-multiple-data (SIMD) cores. Apart from traditional parallel systems, the users must explicitly manage the communication, scheduling and load-balancing to achieve cellpsilas greatest performance. In this paper, a novel heterogeneous data parallel computational model on cell BE is proposed. This aggressive model could not only exploit computing power of SPE but also that of PPE and aggregate them together to achieve high performance. We investigate the performance of this model with naive ray tracing algorithm. The preliminary experimental results validate the efficiency of this model.
In virtual machine (VM) systems, mandatory access control (MAC) enforcement is possible now. This technique is both stronger and more flexible than traditional VM isolation, even if network communication is controlled...
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In virtual machine (VM) systems, mandatory access control (MAC) enforcement is possible now. This technique is both stronger and more flexible than traditional VM isolation, even if network communication is controlled. Unfortunately all of the VM systems with the MAC enforcement does not consider that the MAC controls may be distorted by covert channels, which constitute an important risk in VM systems. Traditional MAC models have difficulties being enforced to reduce the risk of covert flows in VM systems due to the many constraints and the lack of flexibility. In this paper, we identify access control requirements for managing covert channels in VM systems through a critical analysis of the ways by which classical models constrain the covert information flows and we propose a model called the Prioritized Chinese Wall model (PCW) to reduce the risk of covert flows in VM systems while preserving the flexibility. Furthermore, we enforce the policy in sHype/Xen VM system.
The first step towards the information lifecycle management is to differentiate information by values. This paper presents an evaluation model for information value. The idea of the model is from commodity value disci...
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ISBN:
(纸本)9780769532639
The first step towards the information lifecycle management is to differentiate information by values. This paper presents an evaluation model for information value. The idea of the model is from commodity value discipline in economic area. The output of information value evaluation model is determined by information itself which is like commodity price is determined by use-value in economic area. The output of the model is changed around the real information value and controlled by the relationship between information supply and demand. The output of the model is determined by factors from three aspects that are information itself, information supply, and information demand. When applying the model into traditional information management approaches, such as replication, data migration, and backup, those mechanisms control the output of the model through adjusting the ability of information supply.
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