Abstract:Refactoring generic instantiation is valuable for improving reusability and type safety of software. Most of the existing approaches of refactoring legacy code are not suitable for on-line and persistent refactoring because of their complexity. This paper proposes an instantiation refactoring approach for Java programs based on an extended variable type analysis algorithm. A generic type propagation graph is constructed, and new constructs used to express generic type analysis are added to the graph, so it is suitable to do a generic variable field sensitive type analysis. The paper also discusses how to use alias information to improve the refactoring. The case study shows that the results are satisfactory.

Abstract:This paper has considered the problem of preemptively scheduling a set of independent periodic hard real-time tasks in primary-backup based multiprocessor systems. An efficient scheduling algorithm—Task Partition based Fault Tolerant Rate-Monotonic (TPFTRM) is proposed which extends RM algorithm to primary-backup based multiprocessor to provide fault tolerance. Compared with previous scheduling algorithms in this area, TPFTRM abandons active backup copies and only uses passive and overlapping backup copies to maximize the backup over-booking and deallocation, thus improves the scheduling performance. Moreover, TPFTRM proposes the task partitioning and processors grouping technique, which reduce the scheduling computation time and also make an easy way to understand and implement it. Extensive simulations experiments are also carried out based on task sets with different parameters. And the simulation result shows a remarkable saving of processors as well as scheduling computation time compared with previous algorithms, which proves the feasibility and effectiveness of the oposed TPFTRM algorithm.

Abstract:A test oracle in software testing is a mechanism for checking whether the program under test behaves correctly for any execution. In some practical situations, oracles can be unavailable or too xpensive to apply. Metamorphic testing (MT) was proposed to alleviate this problem so that software can be delivered under the time-to-market pressure. However, the effectiveness of MT has not been studied adequately. This paper conducts a controlled experiment to investigate the cost effectiveness of using MT. The fault detection capability and time cost of MT are compared with the standard assertion checking method. The results show that MT has potentials to detect more faults than the assertion checking method. The experimental results also show a trade-off between the two testing methods: MT can be less efficient but more effective, and can be defined at a coarser level of granularity than the assertion checking method.

Abstract:To solve the problem that rules in the existing context-aware systems are manually specified by developers or users, an automatic rule generation method is proposed. Context-Aware systems are regarded as decision systems, and context information are reduced with discernibility matrix so as to generate rules. Because the data that can be utilized are limited, the generated rules can not entirely cover the domains of contexts. The rule matches current context probably does not exist. A rule matching algorithm is presented as the solution to this problem. Finally, the efficiency and effectivity of the proposed method is verified.

Abstract:Schema matching is a basic problem in many database application domains, such as data integration, E-business, data warehousing and semantic query processing. Recently it has become a research hotspot, and most of the achievements are about the use of element’s own information. Research about element’s own information is very mature at present. As an important piece of information in a schema, structure information can be useful information for schema matching, but the research of structure information is far behind that of element’s own information. This paper divides the similarity between two elements into linguistic similarity and structural similarity, and gets the structural similarity by a new statistic method, and then gets the matching probability by integrating the linguistic similarity and structural similarity. At last, the paper gets the mapping between schema elements according to the matching probability. Extensive simulation experiments are conducted and the results show that this algorithm is better than other algorithms in various performance metrics.

Abstract:This paper proposes a weighted codebook vector representation and an action graph model for view-invariant human action recognition. A video is represented as a weighted codebook vector combining dynamic interest points and static shapes. This combined representation has strong noise robusticity and high classification performance on static actions. Several 3D key poses are extracted from the motion capture data or points cloud data, and a set of primitive motion segments are generated. A directed graph called Essential Graph is built of these segments according to self-link, forward-link and back-link. Action Graph is generated from the essential graph projected from a wide range of viewpoints. This paper uses Na?ve Bayes to train a statistical model for each node. Given an unlabeled video, Viterbi algorithm is used for computing the match score between the video and the action graph. The video is then labeled based on the maximum score. Finally, the algorithm is tested on the IXMAS dataset, and the CMU motion capture library. The experimental results demonstrate that this algorithm can recognize the view-invariant actions and achieve high recognition rates.

Abstract:In recent years, Internet traffic classification using machine learning has become a new direction in network measurement. Being simple and efficient Na?ve Bayes and its improved methods have been widely used in this area. But these methods depend too much on probability distribution of sample spacing, so they have connatural instability. To handle this problem, a new method based on C4.5 decision tree is proposed in this paper. This method builds a classification model using information entropy in training data and classifies flows just by a simple search of the decision tree. The theoretical analysis and experimental results show that there are obvious advantages in classification stability when C4.5 decision tree method is used to classify Internet traffic.

Abstract:The cluster-based hierarchical topology control has been widely studied and applied in wireless sensor networks. But because of the open nature and limited resource of the sensor network, clustering protocols are vulnerable to the misuse and disruption attacks from the adversaries. As a result, the security of the clustering protocols is a basic requirement for its wide application. A distributed secure clustering protocol is proposed, in which the secure network initialization, random number broadcast from the base station and one-way hash chain are used to achieve the resiliency against possible attacks including node personating, cluster-head occupying, malicious cluster-member recruiting and multiple cluster-membership attacks. The security and cost of the protocol are evaluated and the results show the resiliency and efficiency of the proposed protocol.

Abstract:The interference will greatly influence the performances of networks on its throughput, energy consumption, and lifetime in mobile ad hoc networks (MANET). On the basis of the existing interference models founded on the number and distribution position of the neighbor nodes, the traffic load of neighbors is further considered and an interference model based on traffic load is proposed. Based on the new interference model, a traffic load-based interference-aware routing (TIR) protocol is proposed, which chooses the routing path with the minimal interference between the source node and the destination node to reduce the possible interference generated when a packet is being forwarded. The results of the simulations show that the proposed interference model based on traffic load suits the characteristic of the MANET, and the TIR protocol obviously improves the network’s lifetime, communication delay and throughput.

Abstract:In a multi-hop wireless sensor network (WSN), the sensors closest to the sink tend to deplete their energy faster than other sensors, which is known as an energy hole around the sink. No more data can be delivered to the sink after an energy hole appears, while a considerable amount of energy is wasted and the network lifetime ends prematurely. This paper investigates the energy hole problem, and based on the improved corona model with levels, it concludes that the assignment of transmission ranges of nodes in different coronas is an effective approach for achieving energy-efficient network. It proves that the optimal transmission ranges for all areas is a multi-objective optimization problem (MOP), which is NP hard. The paper proposes an ACO (ant colony optimization)-based distributed algorithm to prolong the network lifetime, which can help nodes in different areas to adaptively find approximate optimal transmission range based on the node distribution. Furthermore, the simulation results indicate that the network lifetime under this solution approximates to that using the optimal list. Compared with existing algorithms, this ACO-based algorithm can not only make the network lifetime be extended more than two times longer, but also have good performance in the non-uniform node distribution.

Abstract:To handle routing void of greedy geographical routing in wireless sensor networks, an efficiency adaptive void-handle algorithm is proposed, which is based on route signs that are distributed extracted and eliminated iteratively. Probes are sent by source to extract the route signs on the greedy path to destination. Based on the local planar graph, probes can take a clockwise (anticlockwise) traversal using the right (left) hand rule in perimeter mode, when it reaches the routing void. At the same time, route signs are distributed extracted and eliminated iteratively. The route signs are feedback to source and can guide the data packets delivered from source to destination never meeting routing void. Simulation shows that the algorithm can acquire a suboptimal routing path, with a high QoS performance in delivery delay and a mean throughout, so it can be applied to greedy geographical routing in large scale wireless sensor networks which have routing voids.

Abstract:With the dramatic increase in the scale of computing, the applications of network storage systems become wider, and the requirements for their I/O performance are also higher. Now with I/O heavy loaded, it becomes meaningful to cache data by using low-speed media in the I/O path between the client and network storage systems. In this paper, a cache system prototype D-Cache is designed and implemented based on disk media at block level for storage system. A two-level structure is adopted to manage disk cache and a corresponding cache management algorithm is provided for it at block level. The algorithm effectively solves the management problem of disk cache brought by the low-speed characteristic of disk media. By the use of bitmap, the cache management algorithm also eliminates the overhead of Copy on Write operations caused by write miss of disk cache. Experimental results show that the prototype can efficiently improve the overall performance for storage system with I/O heavy loaded.

Abstract:Grid computing is currently an important research area and task scheduling is a basal part of it. The performance of task scheduling directly affects grid QoS. A task scheduling algorithm based on multidimensional performance clustering of grid service resources, MPCGSR (task scheduling algorithm based on multidimensional performance clustering of grid service resources), is proposed for shortening the completion time of task scheduling and improving task scheduling performance. In the algorithm, combined with the theory of small world, the multidimensional performance clustering of service resources is executed in advance based on the hypergraph model of grid service resources constructed according to characteristics of grid resources such as its huge numbers, heterogeneity and multiplicity. Tasks are matched to clustering resources and scheduled. Simulation results show that it is an effective grid task scheduling algorithm that is superior to other kindred algorithms.

Abstract:Most existing trust negotiation languages can not simultaneously have the following important functions: Distributed trust proving, complicated access control definition and negotiation-related constraints. Based on RT (role-based trust-management) language, this paper proposes a distributed trust proving and negotiation orientated language RTP (role-based trust proving). It can support distributed trust proving, define complicated roles, protect the policy’s sensitive information and avoid unrelated credential fetching. Both the syntax and semantics of RTP are introduced. The paper also designs a distributed trust proving and negotiation algorithm based on RTP to demonstrate the efficiency of RTP. Experimental results show that the algorithm supports the functions aimed by RTP, and outperforms the traditional trust negotiation in terms of both time and number of credential transfers.

Abstract:Address plays an important role in WSN (wireless sensor networks), which is used to identify sensor node and enable communication protocols. Due to the numerous sensor nodes and network dynamics in WSN, it is difficult even impossible to configure address for each node manually. With its unique characteristics, addressing protocols for TCP/IP and ad hoc networks are not suitable for WSN. So addressing auto-configuration protocol for WSN has to be devised. Firstly, the need for addressing protocol in WSN is analyzed. The research issues and challenges of designing addressing protocol are also summarized. Then, the present representative addressing protocols are classified, introduced in detail and compared in characteristics and performance. Finally, the open issues and future research directions are pointed out.

Abstract:Authentication test is a newly presented method that testifies protocols’ authentication properties. Its proving process is simple and precise; unfortunately it can not analyze protocols with test components multi-encrypted. This paper analyzes the authentication test scheme improved by Perrig and Song and points out its deficiency. Then it proposes an Enhanced Authentication Test theory and proves its soundness in formal. The enhanced authentication test lifts the restriction that test component can not be multi-encrypted in protocol messages, also repairs the inaccuracies in Perrig’s scheme.

Abstract:Cryptographic workflow is a special cryptography system working model in multi-user situations, in which a message is encrypted according to some policy so that only entities guided by the policy are able to decrpt the message. To realize the unforgeability of key encapsulation in without escrow cryptographic workflow, a new key encapsulation mechanism supporting cryptographic workflow based on signcryption is defined. Firstly, a generic model of key encapsulation supporting cryptographic workflow is defined. The corresponding security model of the generic model is also given. Following the generic model, a construction scheme for key encapsulation mechanism supporting cryptographic workflow is proposed by combining secret sharing scheme, ID-based encryption scheme and signcryption scheme. The security of the proposed scheme is proved in standard model with sequences of game. The proposed scheme can satisfy the receiver security and the external security characters in cryptographic work.

Abstract:A type-inference-based formal method is proposed for verifying an ad-hoc security routing protocol in this paper. A calculus, called NCCC (neighborhood-constraint communication calculus), is defined to specify the protocol. The security property of the protocol is described with typing rules in a type system. Based on the Dolev-Yao model, an attacker model, called the message set of protocol format, is refined. At last, the simplified version of SAODV (secure ad hoc on-demand routing protocol) is verified with this method. With the type- inference-based formal method, not only is the security of protocols verified, but also the attacke examples are predicted. The complexity of inference is reduced significantly for refining the message set of protocol.

Abstract:With the rapid growth of online RDF data, emerging semantic search engines facilitate user’s searching of RDF (resource description framework) data. It is an open question to all semantic search engines how to find sites containing semantic Web information resources automatically and collect them efficiently. Firstly, the paper introduces a Linking Model of the Semantic Web Sites. The model characterizes the relations among Semantic Web Sites, Semantic Web Information Resources, RDF Models and Semantic Web Entities. This paper discusses the ownerships of Semantic Web Entities based on this model. It also defines a Site Dependency Graph in virtue of the model, and presents a set of ranking algorithms for Semantic Web Sites. Primary tests of these algorithms have been performed in a real-world semantic search engine. Experimental results show that this approach is effective in finding and ranking Semantic Web Sites.

Abstract:This paper proposes an effective method for computing optimal state transition probabilities for software reliability estimation based on a Markov usage model. This method uses Cross-Entropy to measure the differences between the operational profile and the sampling distribution with zero variance. By adjusting the probabilities of state transitions during test, an iterative method based on the Cross-Entropy is proposed for this choice, and an unbiased reliability estimator with zero variance is obtained. Simulation results show that the testing profile with Cross-Entropy method performs significantly better than the simulated annealing algorithm. Moreover, this strategy can more effectively accelerate software statistical testing.

Abstract:Similarity search has attracted many researchers from various communities (real-time stock quotes, network security, sensor networks). Due to the infinite, continuous, fast and real-time properties of the data from these communities, a method is needed for online similarity search in data stream. This paper first proposes the lower bound function LB_seg_WF_global for DTW (dynamic time warping) in the presence of global warping constraints and LB_seg_WF for DTW without global warping constraints, which are not applied to any index structures. They are segmented DTW techniques, and can be applied to sequences and queries of varying lengths in data stream. Next, several tighter lower bounds are proposed to improve the approximate degree of the LB_seg_WF_global and LB_seg_WF. Finally, to deal with the possible continuously non-effective problem of LB_seg_WF_global or LB_seg_WF in data stream, it is believed that lower-bound LB_WF_global (in the presence of global warping constraints) and lower-bound LB_WF, upper-bound UB_WF (without global warping constraints) can fast estimate DTW and hence reduce a lot of redundant computations by incrementally computing. The theoretical analysis and statistical experiments confirm the validity of the proposed methods.

Abstract:The open, sharing and anonymous nature of peer-to-peer (P2P) networks has made it popular in many large-scale distributed applications over the Internet. However, due to the fact that resource-sharing activity of a peer in P2P networks is a volunteer behavior and it is not responsible for its irresponsible bartering history, the trust relationship between participants can not be constructed only on the traditional trust mechanism. A feasible resolution derived from the trust relationship in social networks, is to establish a reputation based global trust model. The previous work about the global trust model is mostly based on the assumption that the peer with higher trust value will provide more honest feedbacks, and make the quality of feedback of a peer be approximately equal to that of service of the peer. However, this is not always true. To solve this problem, this paper proposes a robust feedback credibility (FC) based distributed P2P global trust model (FCTrust), to quantify and evaluate the trustworthiness of participants, and gives the mathematic analyses and distributed implementation method. Theoretical analyses and simulation experiments show that FCTrust has advantages in combating various malicious behaviors such as dishonest feedbacks from malicious peers, the collusion and the strategic attacks to the trust model itself, over the current global trust models, and demonstrates more robustness and effectiveness.

Abstract:In this paper, an anomaly detection method is proposed based on the summary data structure—sketch. It records the network traffic information in sketch online and detects anomalies at every circle. After using EWMA forecasting model to get each circle’s forecast sketch, this paper computes the errors between the recoded sketch and forecast sketch. Then, the network traffic change reference is constructed by establishing the Mean-Standard deviation model on the error sketch. The method is effective in detecting DDOS attack, scan attack and so on. Particularly, it can track the IP address of anomaly. Evaluated by the experiment, this method can detect anomaly in the backbone network with small computing and memory resource.

Abstract:To improve the inefficiency of the existing key distribution protocols in the secure broadcasting, an ideal multi-recipient public key encryption scheme to achieve the secret broadcasting is proposed. Based on Shamir’s threshold secret sharing scheme, a multi-recipient public key encryption scheme of the IND-CPA security is proposed on bilinear pairing on elliptic curve. And then, extension is made on the proposed scheme to construct a new multi-recipient public key encryption scheme with the IND-CCA2 security. Based on the Bilinear Decisional Diffie-Hellman assumption and the Gap Bilinear Diffie-Hellman assumption, their security claimed above is proved. At the same time, analyses are made on the correctness and performance of the scheme. Analyses show that the proposed scheme is a efficient and secure public-key encryption scheme, in which, a ciphertext encrypted by an encryption key can be decrypted by a number of decryption keys. This makes it play an important role in many applications. Especially in the secure broadcasting, it can be applied to securely broadcast sensitive information in an unsafe and open network situation.

Abstract:The education resource grid is an effective measure to solve the problem of sharing distributed education resources at present. First, with regard to the education resource sharing in secondary and elementary schools, a hierarchy model of education resource grid is proposed and the functions of nodes in each layer are defined in this paper. By comparing with the European Data Grid, the education resource grid is analyzed with its characteristics. Then based on the hierarchy grid model, some factors, which influence the performance of replica creation strategy, are analyzed and a dynamic replica creation strategy (EDRS) is proposed by introducing two parameters, i.e., the network bandwidth and file size. With the data grid simulation tool OptorSim, the performances of EDRS with Caching-LRU, Caching-LFU and the economic model strategy are compared respectively. At last, the influence of different strategies on the performance of the education resource grid system is analyzed by synthesizing each parameter. The result indicates that the EDRS has a better system performance in applications of the education resource grid.