Model checking is used mainly to check if a system satisfies the specifications expressed in temporal logic and people pay little attention to the model checking problem for logics of knowledge. However, in the distri...
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Model checking is used mainly to check if a system satisfies the specifications expressed in temporal logic and people pay little attention to the model checking problem for logics of knowledge. However, in the distributed systems community, the desirable specifications of systems and protocols are expressed widely in logics of knowledge. The model checking approaches for the temporal logic of knowledge are discussed. On the base of SMV (symbolic model verifier), according to the semantics of knowledge and set theory, several approaches for model checking of knowledge and common knowledge are presented. These approaches make SMV's functions extended from temporal logics to temporal logics of knowledge. They also correspond to other model checking approaches and tools where the output is the set of states.
Role-based Access Control (RABC) is an important information security model. In order to describe the information flow based on this model, a new security information flow model based on roles is given. The object is ...
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Role-based Access Control (RABC) is an important information security model. In order to describe the information flow based on this model, a new security information flow model based on roles is given. The object is expended, the basic principle of the RBAC model is used, the safe classify of the object is divided by its role set, and the information flow role is described with the included relation of the role set of two objects. By strict mathematical verification, this new information flow model satisfies the character of finite lattice and least upper bound operator, and it is reasonable and safe. Lastly one simple application is given.
As one stream standard which will be produced by the ITU-T and ISO in the future, Draft JVT (joint video team) is a new video-audio coding standard. Its goal is to produce a significant comp.ession performance relativ...
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As one stream standard which will be produced by the ITU-T and ISO in the future, Draft JVT (joint video team) is a new video-audio coding standard. Its goal is to produce a significant comp.ession performance relative to all the existing video coding standards in bit saving, procession quality and comp.ession efficiency by some measures which include slice technology, high resolution variable pixels, different block sizes and shapes, intra/inter prediction and coding from multiple reference pictures, etc. On the other hand, JVT would be designed to offer a transparent translation over different networks and increase network friendliness by information encapsulation and precedence control technologies. Although the basic coding framework of the standard is similar to that of currently popular video standards, JVT includes many new coding features which are presented in the paper. First, a broad view on video-audio coding standards is given. Second, the structure of JVT is presented. Then, both the detailed technologies which improve on coding efficiency of the VCL (video coding layer) and the key terms which are used in NAL (network abstraction layer) are introduced, which is the core in the paper. Finally, the current problems and the challenges of JVT's future research are discussed and analyzed.
To meet the increasing popularity of secure group-oriented comp.ting, this paper proposes an efficient group key agreement scheme-PAGKA. It combines the merit of key tree and Pairings-based key exchange, and involves ...
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To meet the increasing popularity of secure group-oriented comp.ting, this paper proposes an efficient group key agreement scheme-PAGKA. It combines the merit of key tree and Pairings-based key exchange, and involves members' long-term keys and session random in the group key to avoid dependence on signature or media access control (MAC). The PAGKA protocol suite is communication efficient, and has the following cryptographic properties such as key independence, implicit key authentication, perfect forward secrecy and resistance to known-key attacks and man-in-the-middle attacks. The idea in PAGKA can be used as a general method to extend authenticated two-party key agreement protocol to group settings.
This paper presents a distributed multi-agent planning algorithm based on constraints propagating. In our algorithm, conflicts are detected and resolved through a special type of negotiation among agents, i.e. consist...
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This paper presents a distributed multi-agent planning algorithm based on constraints propagating. In our algorithm, conflicts are detected and resolved through a special type of negotiation among agents, i.e. consistency checking for constraints. The algorithm is sound under deterministic circumstance. In our algorithm, agents only exchange information about actions, casual links and constraints related to conflicts. It is of less communication, higher security than that exchanging the whole plan.
A scheme called Freeze-TCP + is presented to improve the performance of transmission control protocol (TCP) in mobile environment. Freeze-TCP + is based on Freeze-TCP and incorporates network measurement mechanism. Da...
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A scheme called Freeze-TCP + is presented to improve the performance of transmission control protocol (TCP) in mobile environment. Freeze-TCP + is based on Freeze-TCP and incorporates network measurement mechanism. Data sender in Freeze-TCP + would not send all the packets in the window immediately as it does in Freeze-TCP when handover occurs but set its slow start threshold to a measurement result and start to transmit packets from slow start phase. Freeze-TCP + solve the problems that Freeze-TCP faces when handover occurs in heterogeneous networks, i.e., many packets are lost due to burst transmission or the resources in the new network can not be utilized efficiently. Network simulation shows that Freeze-TCP + can improve the performance of Freeze-TCP whatever kinds of handover occur.
The problem of an ogival nose rigid projectile penetrating into a thick target has been considered based on a semi-theoretical model in order to determine the velocity potential and the velocity field in the target. T...
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The problem of an ogival nose rigid projectile penetrating into a thick target has been considered based on a semi-theoretical model in order to determine the velocity potential and the velocity field in the target. The nose shape is simplified as a semi-Rankine ovoid similar to that of real long rod projectiles, and the details in nose shape does not significantly influence the penetration depth and the residual velocity in the case of thick targets. A code was comp.led based on the analysis of velocity and stress fields in targets, and used to calculate penetration and perforation of an ogival nose steel projectile into thick aluminum targets. A good agreement in residual velocity and penetration depth between the calculation and the experiments is achieved without any adjustment in material property parameters.
The mathematical expression of Chinese characters is a novel method to describe Chinese characters. Based on the analysis of comp.nents of Chinese characters, an algorithm of automatic generation of mathematical expre...
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The mathematical expression of Chinese characters is a novel method to describe Chinese characters. Based on the analysis of comp.nents of Chinese characters, an algorithm of automatic generation of mathematical expression is presented. Firstly, about 500 Chinese character comp.nents are chosen, and nine basic properties are selected for each of them: connectivity number, genus number, end number, turn number, joint number, cross number and NMI, HNMI, and VNMI;then by segmenting or combining connective regions, a Chinese character is divided into Chinese character comp.nents;finally, by recognizing the comp.nents and the Chinese character structure, the mathematical expressions are obtained. Satisfying experimental result shows that the correct ratio of mathematical expressions is 92%. Automatic generation of mathematical expressions will facilitate the management and transmission of Chinese information in the fields such as typesetting printing, advertising and package design, network transmission, Chinese mobile communication.
The analysis of a hybrid system using overlapping decomp.sition and expansion method of hybrid Petri net is proposed. First, some related definitions (such as boundedness, reachability and activity are presented) and ...
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The analysis of a hybrid system using overlapping decomp.sition and expansion method of hybrid Petri net is proposed. First, some related definitions (such as boundedness, reachability and activity are presented) and the inclusion principle is expounded. Then, the overlapping decomp.sition and expansion method of hybrid Petri net is introduced and overlapping decomp.sition is used in topological structure of a Petri net model for the hybrid system. The topological structure of the Petri net is analyzed and the overlapping subnet of the Petri net is determined. Finally, an example of the hybrid Petri net is given to illustrate the process of overlapping decomp.sition and expansion. This provides an effective method to analyze a large hybrid system and is helpful to the analysis and control of a comp.ex hybrid system.
Classical Self-Organizing Maps presented by T. Kohonen is performed in the input sample space based on the Euclidean norm. It fails as the distribution of input patterns becomes highly nonlinear. Kernel means, perform...
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Classical Self-Organizing Maps presented by T. Kohonen is performed in the input sample space based on the Euclidean norm. It fails as the distribution of input patterns becomes highly nonlinear. Kernel means, performing a nonlinear data transformation into some high dimensional feature space, increases the probability of the linear separability of the patterns within the feature space. Donald and others map the data in input space into a high-dimension feature space, where SOM algorithm are performed. However, its disadvantage lies in lack of direct descriptions about the clustering's center and result. A novel kernel-based SOM algorithm is proposed. We replace the Euclidean norm in the SOM training procedure with kernels, which is equivalent to change the metric of distance in input space. Multiformity of kernels leads to different metrics of distance in input space, and correspondingly results in SOM classifications. Finally we discuss the robustness and reliability of KSOM by experimenting on Benchmark based on several classical kernel functions.
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