To describe the dynamic propcrty of trust relationship, wt propose atime-related trust model and extend Joang's subjective logic to fit for time-related trust model.The extension includes prepositional conjunction...To describe the dynamic propcrty of trust relationship, wt propose atime-related trust model and extend Joang's subjective logic to fit for time-related trust model.The extension includes prepositional conjunction, disjunction and negation for traditional logic anddiscounting and consensus operators that are evidential operators specially designed for thepropagation and computation of trust relationships. With the extension of subjective logic fortime-related trust, our time-related trust modelis suitable to model the dynamic trust relationshipin practice. Finally an example of reputation assessment is offered to demonstrate the usage of ourtrust model.展开更多
In this paper, we describe and analyze the hypothesis about intrusiontolerance software system, so that it can provide an intended server capability and deal with theimpacts caused by the intruder exploiting the inher...In this paper, we describe and analyze the hypothesis about intrusiontolerance software system, so that it can provide an intended server capability and deal with theimpacts caused by the intruder exploiting the inherent security vulnerabilities. Wepresent someintrusion tolerance technology by exploiting N-version module threshold method in constructingmultilevel secure software architecture, by detecting with hash value, by placing an 'antigen' wordnext to the return address on the stack thatis similar to human immune system, and by adding 'Honeycode' nonfunctional code to disturb intruder, so that the security and the availability of thesoftware system are ensured.展开更多
This paper studies the digit watermark technology of numeric attributes in relational database for database's information security. It proposes a new mechanism based on similar clouds watermark and gives the conce...This paper studies the digit watermark technology of numeric attributes in relational database for database's information security. It proposes a new mechanism based on similar clouds watermark and gives the concept of similar clouds. The algorithm SCWA that can insert the meaning watermark and detect it from the watermarked data is described. The mechanism can effectively and broadly scatter the watermark in the database; therefore the watermark is very robust. Key words copyright protection - digit watermark - similar clouds - clouds model CLC number TP 311. 52 Foundation item: Supported by the National Natural Science Foundation of China (60273072) and 863 Hi-technique Research (2002AA4Z3450)Biography: HUANG Min(1979-), female, Ph. D candidate, research direction: database's information security展开更多
A security kernel architeclrne built on trusted computing platform in thelight of thinking about trusted computing is presented According to this architecture, a newsecurity module TCB (Trusted Computing Base) is adde...A security kernel architeclrne built on trusted computing platform in thelight of thinking about trusted computing is presented According to this architecture, a newsecurity module TCB (Trusted Computing Base) is added to the operation system kerneland twooperation interface modes are provided for the sake of self-protection. The security kernel isdivided into two parts and trusted mechanism Is separated from security functionality. Ihe TCBmodule implements the trusted mechanism such as measurement and attestation, while the othercomponents of security kernel provide security functionality based on these mechanisms. Thisarchitecture takes full advantage of functions provided by trusted platform and clearly defines thesecurity perimeter of TCB so as to assure stlf-securily from architcetmal vision. We also presentfunction description of TCB and discuss the strengths and limitations comparing with other relatedresearches.展开更多
Integrating with the respective advantages of XML Schema and Ontology, this paper puts forward a semantic information processing architecture-OBSA to solve the problem of heterogeneity of information sources and uncer...Integrating with the respective advantages of XML Schema and Ontology, this paper puts forward a semantic information processing architecture-OBSA to solve the problem of heterogeneity of information sources and uncertainty of semantic. It introduces anF-Logic based semantic information presentation mechanism, presents a design of an ontology-based semantic representation language and a mapping algorithm converting Ontology to XML DTD/Schema, and an adapter framework for accessing distributed and heterogeneous information. Key words ontology - F-Logic - semantic adapter CLC number TP 391 Foundation item: Supported by the Natural Science Fundation of Hubei of China (2003ABA049) and the Natural Science Fundation of Education Agency of Hubei of China (2003A012)Biography: GU Jin-guang (1974-), male, Ph. D candidate, lecturer, research direction: distributed computing system, software engineering and knowledge engineering.展开更多
In recent years, Web services and Peer-to-Peer (or simply P2P) appear as two of the hottest research topics in network computing. On the one hand, by adopting a decentralized, network-based style, P2P technologies can...In recent years, Web services and Peer-to-Peer (or simply P2P) appear as two of the hottest research topics in network computing. On the one hand, by adopting a decentralized, network-based style, P2P technologies can make P2P systems enhance overall reliability and fault-tolerance, increase autonomy, and enable ad-hoc communication and collaboration. On the other hand, Web services provides a good approach to integrate various heterogeneous systems and applications into a cooperative environment. This paper presents the techniques of combining Web services and P2P technologies into GIS to construct a new generation of GIS, which is more flexible and cooperative. As a case study, an ongoing project JGWS is introduced, which is an experimental GIS Web services platform built on JXTA. This paper also explores the schemes of building GIS Web services in a P2P environment.展开更多
Several models of measuring case similarity in CBR systems are deeply explored. We also discuss the case matching process, and present three matching functions. Finally, we illustrate the significance of the models in...Several models of measuring case similarity in CBR systems are deeply explored. We also discuss the case matching process, and present three matching functions. Finally, we illustrate the significance of the models in CBR(Case Based Reasoning) systems implementation. Key words CBR - similarity - matching CLC number TP 182 Foundation item: Supported by the Natural Science Foundation of Hubei Province (2001ABB058) and the Project Sponsored by the Scientific Research Foundation for the Returned Overseas Chinese Scholars, State Education MinistryBiography: NIU Xiao-tai (1971-), male, Ph. D candidate, Research direction: decision support system展开更多
The thinking of co evolution is applied to the optimization of retaining and protecting structure for deep foundation excavation, and the system of optimization of anchored row piles for deep foundation pit has been a...The thinking of co evolution is applied to the optimization of retaining and protecting structure for deep foundation excavation, and the system of optimization of anchored row piles for deep foundation pit has been already developed successfully. For the co evolution algorithm providing an evolutionary mechanism to simulate ever changing problem space, it is an optimization algorithm that has high performance, especially applying to the optimization of complicated system of retaining and protecting for deep foundation pit. It is shown by many engineering practices that the co evolution algorithm has obvious optimization effect, so it can be an important method of optimization of retaining and protecting for deep foundation pit. Here the authors discuss the co evolution model, object function, all kinds of constraint conditions and their disposal methods, and several key techniques of system realization.展开更多
The meanings of parameters of software reliabi- lity models are investigated in terms of the process of the software testing and in terms of other measurements of software. Based on the investigation, the empirical e...The meanings of parameters of software reliabi- lity models are investigated in terms of the process of the software testing and in terms of other measurements of software. Based on the investigation, the empirical estimation of the parameters is addressed. On one hand, these empirical estimates are also measurements of the software, which can be used to control and to optimize the process of the software development. On the other hand, by treating these empirical estimates as Bayes priors, software reliability models are extended such that the engineers’ experience can be integrated into and hence to improve the models.展开更多
Despite of its great efficiency for pattern classification, proximal supportvector machines (PSVM), a new version of SVM proposed recently, is sensitive to noise and outliers.To overcome the drawback, this paper modif...Despite of its great efficiency for pattern classification, proximal supportvector machines (PSVM), a new version of SVM proposed recently, is sensitive to noise and outliers.To overcome the drawback, this paper modifies PSVM by associating a weightvalue with each input dataof PSVM. The distance between each data point and the center of corresponding class is used tocalculate the weight value. In this way, the effect of noise is reduced. The experiments indicatethat new SVM, weighted proximal support vector machine (WPSVM), is much more robust to noise thanPSVM without loss of computationally attractive feature of PSVM.展开更多
In order to process video data efficiently, a video segmenting technique must be required. We propose a fast shot transition detecting algorithm directly on MPEG compressed video sequence. The algorithm can detect not...In order to process video data efficiently, a video segmenting technique must be required. We propose a fast shot transition detecting algorithm directly on MPEG compressed video sequence. The algorithm can detect not only abrupt transition, but also gradual transition. The computing cost of the algorithm is low, because we directly use the type of macroblocks and motion vectors that MPEG compressed video provides. The result of experiment is rather well.展开更多
A GF(p) elliptic curve cryptographic coprocessor is proposed and implemented on Field Programmable Gate Array (FPGA). The focus of the coprocessor is on the most critical, complicated and time-consuming point multipli...A GF(p) elliptic curve cryptographic coprocessor is proposed and implemented on Field Programmable Gate Array (FPGA). The focus of the coprocessor is on the most critical, complicated and time-consuming point multiplications. The technique of coordinates conversion and fast multiplication algorithm of two large integers are utilized to avoid frequent inversions and to accelerate the field multiplications used in point multiplications. The characteristic of hardware parallelism is considered in the implementation of point multiplications. The coprocessor implemented on XILINX XC2V3000 computes a point multiplication for an arbitrary point on a curve defined over GF(2192?264?1) with the frequency of 10 MHz in 4.40 ms in the average case and 5.74 ms in the worst case. At the same circumstance, the coprocessor implemented on XILINX XC2V4000 takes 2.2 ms in the average case and 2.88 ms in the worst case.展开更多
A scheme to construct signatures automatically for Snort from the data captured by honeypots is presented. With this scheme intrusion detection systems can be quickly updated to detect new intrusions soon when happen....A scheme to construct signatures automatically for Snort from the data captured by honeypots is presented. With this scheme intrusion detection systems can be quickly updated to detect new intrusions soon when happen. The idea is based on the observation that any traffic to and from honeypots represents abnormal activities, so data patterns extracted from these packets can be used by misuse detection system to identify new attacks. The algorithm of constructing rules is discussed. Experiment illustrates the effectiveness of the scheme.展开更多
This paper proposes an improved non-repudiation protocol after pointing out two attacks on an existing non-repudiation protocol. To analyze the improved protocol, it also proposes an extension of Kailar logic. Using t...This paper proposes an improved non-repudiation protocol after pointing out two attacks on an existing non-repudiation protocol. To analyze the improved protocol, it also proposes an extension of Kailar logic. Using the extended Kailar logic, the security analysis of the improved prototocol has been presented. Key words non-repudiation protocol - extended Kailar logic - converse assumption procedure CLC number TP 393. 08 Foundation item: Supported by the National Natural Science Foundation of China (90104005) and the Doctoral Science Foundation of Ministry of Education (20020486046)Biography: Li Li(1976-), female, Ph. D candidate, research direction: network security and formal analysis of security protocol.展开更多
Computer simulations of simple exact lattice models are an aid in the study of protein folding process. We proposed a new search strategy by two hierarchy optimization techniques, which is shown very efficient.
In this paper, we employ genetic algorithms to solve the migration problem (MP). We propose a new encoding scheme to represent trees, which is composed of two parts: the pre-ordered traversal sequence of tree vertices...In this paper, we employ genetic algorithms to solve the migration problem (MP). We propose a new encoding scheme to represent trees, which is composed of two parts: the pre-ordered traversal sequence of tree vertices and the children number sequence of corresponding tree vertices. The proposed encoding scheme has the advantages of simplicity for encoding and decoding, ease for GA operations, and better equilibrium between exploration and exploitation. It is also adaptive in that, with few restrictions on the length of code, it can be freely lengthened or shortened according to the characteristics of the problem space. Furthermore, the encoding scheme is highly applicable to the degree-constrained minimum spanning tree problem because it also contains the degree information of each node. The simulation results demonstrate the higher performance of our algorithm, with fast convergence to the optima or sub-optima on various problem sizes. Comparing with the binary string encoding of vertices, when the problem size is large, our algorithm runs remarkably faster with comparable search capability. Key words distributed information retrieval - mobile agents - migration problem - genetic algorithms CLC number TP 301. 6 Foundation item: Supported by the National Natural Science Foundation of China (90104005), the Natural Science Foundation of Hubei Province and the Hong Kong Polytechnic University under the grant G-YD63Biography: He Yan-xiang (1952-), male, Professor, research direction: distributed and parallel processing, multi-agent systems, data mining and e-business.展开更多
Frequent Pattern mining plays an essential role in data mining. Most of the previous studies adopt an Apriori-like candidate set generation-and-test approach. However, candidate set generation is still costly, especia...Frequent Pattern mining plays an essential role in data mining. Most of the previous studies adopt an Apriori-like candidate set generation-and-test approach. However, candidate set generation is still costly, especially when there exist prolific patterns and/or long patterns. We introduce a novel frequent pattern growth (FP-growth) method, which is efficient and scalable for mining both long and short frequent patterns without candidate generation. And build a new projection frequent pattern tree (PFP-tree) algorithm, which not only heirs all the advantages in the FP-growth method, but also avoids it's bottleneck in database size dependence when constructing the frequent pattern tree (FP-tree). Efficiency of mining is achieved by introducing the projection technique, which avoid serial scan each frequent item in the database, the cost is mainly related to the depth of the tree, namely the number of frequent items of the longest transaction in the database, not the sum of all the frequent items in the database, which hugely shortens the time of tree-construction. Our performance study shows that the PFP-tree method is efficient and scalable for mining large databases or data warehouses, and is even about an order of magnitude faster than the FP-growth method.展开更多
Based on the difficulty in computing discrete logarilhm and square 1001 onsome special conditions, we propose a basic threshold seeret sharing scheme for multiple secretswith multiple policies, which allows a group of...Based on the difficulty in computing discrete logarilhm and square 1001 onsome special conditions, we propose a basic threshold seeret sharing scheme for multiple secretswith multiple policies, which allows a group of users to share multiple secrttkeys and only onesecret shadow to be ktpt by each user. An efficient threshold decryption scheme with multiplepolicies is designed on the basis of the basic threshold scheme. This decryption scheme allowsmultiple secret keys to he shared among a groupof users, and each user to ketp only one secretshadow. Different public keys can be used to encrypt documents. If and only if the number ofcooperated users who koop the secret shadows is greater than or c-qual to the threshold value of thecorresponding secret key, they can cooperate to decrypt the documents. It is proved that theproposed scheme has very strong security, unless the attackers can solve the discrete logarithmproblem and the square root problem.展开更多
In this paper, H∞ optimal model reduction for singular fast subsystems will be inves-tigated. First, error system is established to measure the error magnitude between the original andreduced systems, and it is demon...In this paper, H∞ optimal model reduction for singular fast subsystems will be inves-tigated. First, error system is established to measure the error magnitude between the original andreduced systems, and it is demonstrated that the new feature for model reduction of singular systemsis to make H∞ norm of the error system finite and minimal. The necessary and su?cient conditionis derived for the existence of the H∞ suboptimal model reduction problem. Next, we give an exactand practicable algorithm to get the parameters of the reduced subsystems by applying the matrixtheory. Meanwhile, the reduced system may be also impulsive. The advantages of the proposedalgorithm are that it is more ?exible in a straight-forward way without much extra computation, andthe order of the reduced systems is as minimal as possible. Finally, one illustrative example is givento illustrate the e?ectiveness of the proposed model reduction approach.展开更多
文摘To describe the dynamic propcrty of trust relationship, wt propose atime-related trust model and extend Joang's subjective logic to fit for time-related trust model.The extension includes prepositional conjunction, disjunction and negation for traditional logic anddiscounting and consensus operators that are evidential operators specially designed for thepropagation and computation of trust relationships. With the extension of subjective logic fortime-related trust, our time-related trust modelis suitable to model the dynamic trust relationshipin practice. Finally an example of reputation assessment is offered to demonstrate the usage of ourtrust model.
基金Supported by the National Natural Science Foun dation of China (90104005,60373087, 60473023),the Ph. D Pro grams Foundation of Ministry of Education of China(20020486046)
文摘In this paper, we describe and analyze the hypothesis about intrusiontolerance software system, so that it can provide an intended server capability and deal with theimpacts caused by the intruder exploiting the inherent security vulnerabilities. Wepresent someintrusion tolerance technology by exploiting N-version module threshold method in constructingmultilevel secure software architecture, by detecting with hash value, by placing an 'antigen' wordnext to the return address on the stack thatis similar to human immune system, and by adding 'Honeycode' nonfunctional code to disturb intruder, so that the security and the availability of thesoftware system are ensured.
文摘This paper studies the digit watermark technology of numeric attributes in relational database for database's information security. It proposes a new mechanism based on similar clouds watermark and gives the concept of similar clouds. The algorithm SCWA that can insert the meaning watermark and detect it from the watermarked data is described. The mechanism can effectively and broadly scatter the watermark in the database; therefore the watermark is very robust. Key words copyright protection - digit watermark - similar clouds - clouds model CLC number TP 311. 52 Foundation item: Supported by the National Natural Science Foundation of China (60273072) and 863 Hi-technique Research (2002AA4Z3450)Biography: HUANG Min(1979-), female, Ph. D candidate, research direction: database's information security
基金Supported by the National Basic Research Programof China (G1999035801)
文摘A security kernel architeclrne built on trusted computing platform in thelight of thinking about trusted computing is presented According to this architecture, a newsecurity module TCB (Trusted Computing Base) is added to the operation system kerneland twooperation interface modes are provided for the sake of self-protection. The security kernel isdivided into two parts and trusted mechanism Is separated from security functionality. Ihe TCBmodule implements the trusted mechanism such as measurement and attestation, while the othercomponents of security kernel provide security functionality based on these mechanisms. Thisarchitecture takes full advantage of functions provided by trusted platform and clearly defines thesecurity perimeter of TCB so as to assure stlf-securily from architcetmal vision. We also presentfunction description of TCB and discuss the strengths and limitations comparing with other relatedresearches.
文摘Integrating with the respective advantages of XML Schema and Ontology, this paper puts forward a semantic information processing architecture-OBSA to solve the problem of heterogeneity of information sources and uncertainty of semantic. It introduces anF-Logic based semantic information presentation mechanism, presents a design of an ontology-based semantic representation language and a mapping algorithm converting Ontology to XML DTD/Schema, and an adapter framework for accessing distributed and heterogeneous information. Key words ontology - F-Logic - semantic adapter CLC number TP 391 Foundation item: Supported by the Natural Science Fundation of Hubei of China (2003ABA049) and the Natural Science Fundation of Education Agency of Hubei of China (2003A012)Biography: GU Jin-guang (1974-), male, Ph. D candidate, lecturer, research direction: distributed computing system, software engineering and knowledge engineering.
文摘In recent years, Web services and Peer-to-Peer (or simply P2P) appear as two of the hottest research topics in network computing. On the one hand, by adopting a decentralized, network-based style, P2P technologies can make P2P systems enhance overall reliability and fault-tolerance, increase autonomy, and enable ad-hoc communication and collaboration. On the other hand, Web services provides a good approach to integrate various heterogeneous systems and applications into a cooperative environment. This paper presents the techniques of combining Web services and P2P technologies into GIS to construct a new generation of GIS, which is more flexible and cooperative. As a case study, an ongoing project JGWS is introduced, which is an experimental GIS Web services platform built on JXTA. This paper also explores the schemes of building GIS Web services in a P2P environment.
文摘Several models of measuring case similarity in CBR systems are deeply explored. We also discuss the case matching process, and present three matching functions. Finally, we illustrate the significance of the models in CBR(Case Based Reasoning) systems implementation. Key words CBR - similarity - matching CLC number TP 182 Foundation item: Supported by the Natural Science Foundation of Hubei Province (2001ABB058) and the Project Sponsored by the Scientific Research Foundation for the Returned Overseas Chinese Scholars, State Education MinistryBiography: NIU Xiao-tai (1971-), male, Ph. D candidate, Research direction: decision support system
基金National Natural Science Foundation of China( 5 986 80 0 1)
文摘The thinking of co evolution is applied to the optimization of retaining and protecting structure for deep foundation excavation, and the system of optimization of anchored row piles for deep foundation pit has been already developed successfully. For the co evolution algorithm providing an evolutionary mechanism to simulate ever changing problem space, it is an optimization algorithm that has high performance, especially applying to the optimization of complicated system of retaining and protecting for deep foundation pit. It is shown by many engineering practices that the co evolution algorithm has obvious optimization effect, so it can be an important method of optimization of retaining and protecting for deep foundation pit. Here the authors discuss the co evolution model, object function, all kinds of constraint conditions and their disposal methods, and several key techniques of system realization.
文摘The meanings of parameters of software reliabi- lity models are investigated in terms of the process of the software testing and in terms of other measurements of software. Based on the investigation, the empirical estimation of the parameters is addressed. On one hand, these empirical estimates are also measurements of the software, which can be used to control and to optimize the process of the software development. On the other hand, by treating these empirical estimates as Bayes priors, software reliability models are extended such that the engineers’ experience can be integrated into and hence to improve the models.
文摘Despite of its great efficiency for pattern classification, proximal supportvector machines (PSVM), a new version of SVM proposed recently, is sensitive to noise and outliers.To overcome the drawback, this paper modifies PSVM by associating a weightvalue with each input dataof PSVM. The distance between each data point and the center of corresponding class is used tocalculate the weight value. In this way, the effect of noise is reduced. The experiments indicatethat new SVM, weighted proximal support vector machine (WPSVM), is much more robust to noise thanPSVM without loss of computationally attractive feature of PSVM.
基金the National Natural Science Foundation of China(60173045/F020204)
文摘In order to process video data efficiently, a video segmenting technique must be required. We propose a fast shot transition detecting algorithm directly on MPEG compressed video sequence. The algorithm can detect not only abrupt transition, but also gradual transition. The computing cost of the algorithm is low, because we directly use the type of macroblocks and motion vectors that MPEG compressed video provides. The result of experiment is rather well.
基金Supported by the National Natural Science Foun dation of China ( 69973034 ) and the National High TechnologyResearch and Development Program of China (2002AA141050)
文摘A GF(p) elliptic curve cryptographic coprocessor is proposed and implemented on Field Programmable Gate Array (FPGA). The focus of the coprocessor is on the most critical, complicated and time-consuming point multiplications. The technique of coordinates conversion and fast multiplication algorithm of two large integers are utilized to avoid frequent inversions and to accelerate the field multiplications used in point multiplications. The characteristic of hardware parallelism is considered in the implementation of point multiplications. The coprocessor implemented on XILINX XC2V3000 computes a point multiplication for an arbitrary point on a curve defined over GF(2192?264?1) with the frequency of 10 MHz in 4.40 ms in the average case and 5.74 ms in the worst case. At the same circumstance, the coprocessor implemented on XILINX XC2V4000 takes 2.2 ms in the average case and 2.88 ms in the worst case.
文摘A scheme to construct signatures automatically for Snort from the data captured by honeypots is presented. With this scheme intrusion detection systems can be quickly updated to detect new intrusions soon when happen. The idea is based on the observation that any traffic to and from honeypots represents abnormal activities, so data patterns extracted from these packets can be used by misuse detection system to identify new attacks. The algorithm of constructing rules is discussed. Experiment illustrates the effectiveness of the scheme.
文摘This paper proposes an improved non-repudiation protocol after pointing out two attacks on an existing non-repudiation protocol. To analyze the improved protocol, it also proposes an extension of Kailar logic. Using the extended Kailar logic, the security analysis of the improved prototocol has been presented. Key words non-repudiation protocol - extended Kailar logic - converse assumption procedure CLC number TP 393. 08 Foundation item: Supported by the National Natural Science Foundation of China (90104005) and the Doctoral Science Foundation of Ministry of Education (20020486046)Biography: Li Li(1976-), female, Ph. D candidate, research direction: network security and formal analysis of security protocol.
文摘Computer simulations of simple exact lattice models are an aid in the study of protein folding process. We proposed a new search strategy by two hierarchy optimization techniques, which is shown very efficient.
文摘In this paper, we employ genetic algorithms to solve the migration problem (MP). We propose a new encoding scheme to represent trees, which is composed of two parts: the pre-ordered traversal sequence of tree vertices and the children number sequence of corresponding tree vertices. The proposed encoding scheme has the advantages of simplicity for encoding and decoding, ease for GA operations, and better equilibrium between exploration and exploitation. It is also adaptive in that, with few restrictions on the length of code, it can be freely lengthened or shortened according to the characteristics of the problem space. Furthermore, the encoding scheme is highly applicable to the degree-constrained minimum spanning tree problem because it also contains the degree information of each node. The simulation results demonstrate the higher performance of our algorithm, with fast convergence to the optima or sub-optima on various problem sizes. Comparing with the binary string encoding of vertices, when the problem size is large, our algorithm runs remarkably faster with comparable search capability. Key words distributed information retrieval - mobile agents - migration problem - genetic algorithms CLC number TP 301. 6 Foundation item: Supported by the National Natural Science Foundation of China (90104005), the Natural Science Foundation of Hubei Province and the Hong Kong Polytechnic University under the grant G-YD63Biography: He Yan-xiang (1952-), male, Professor, research direction: distributed and parallel processing, multi-agent systems, data mining and e-business.
基金the National Natural Science Foundation of China(90104005)
文摘Frequent Pattern mining plays an essential role in data mining. Most of the previous studies adopt an Apriori-like candidate set generation-and-test approach. However, candidate set generation is still costly, especially when there exist prolific patterns and/or long patterns. We introduce a novel frequent pattern growth (FP-growth) method, which is efficient and scalable for mining both long and short frequent patterns without candidate generation. And build a new projection frequent pattern tree (PFP-tree) algorithm, which not only heirs all the advantages in the FP-growth method, but also avoids it's bottleneck in database size dependence when constructing the frequent pattern tree (FP-tree). Efficiency of mining is achieved by introducing the projection technique, which avoid serial scan each frequent item in the database, the cost is mainly related to the depth of the tree, namely the number of frequent items of the longest transaction in the database, not the sum of all the frequent items in the database, which hugely shortens the time of tree-construction. Our performance study shows that the PFP-tree method is efficient and scalable for mining large databases or data warehouses, and is even about an order of magnitude faster than the FP-growth method.
文摘Based on the difficulty in computing discrete logarilhm and square 1001 onsome special conditions, we propose a basic threshold seeret sharing scheme for multiple secretswith multiple policies, which allows a group of users to share multiple secrttkeys and only onesecret shadow to be ktpt by each user. An efficient threshold decryption scheme with multiplepolicies is designed on the basis of the basic threshold scheme. This decryption scheme allowsmultiple secret keys to he shared among a groupof users, and each user to ketp only one secretshadow. Different public keys can be used to encrypt documents. If and only if the number ofcooperated users who koop the secret shadows is greater than or c-qual to the threshold value of thecorresponding secret key, they can cooperate to decrypt the documents. It is proved that theproposed scheme has very strong security, unless the attackers can solve the discrete logarithmproblem and the square root problem.
文摘In this paper, H∞ optimal model reduction for singular fast subsystems will be inves-tigated. First, error system is established to measure the error magnitude between the original andreduced systems, and it is demonstrated that the new feature for model reduction of singular systemsis to make H∞ norm of the error system finite and minimal. The necessary and su?cient conditionis derived for the existence of the H∞ suboptimal model reduction problem. Next, we give an exactand practicable algorithm to get the parameters of the reduced subsystems by applying the matrixtheory. Meanwhile, the reduced system may be also impulsive. The advantages of the proposedalgorithm are that it is more ?exible in a straight-forward way without much extra computation, andthe order of the reduced systems is as minimal as possible. Finally, one illustrative example is givento illustrate the e?ectiveness of the proposed model reduction approach.