- EI核心期刊
In order to deal with the dynamic network virtualization environment and reduce the cost of probe selection, a dynamic probe station selection algorithm based on the greedy method was proposed. The algorithm chooses the nodes that can achieve all the virtual nodes and have the maximum height as the probe station. For the dynamic network environment, this algorithm will dynamically select the probe stations in the two scenarios: node adding and node deleting. Simulations show that, compared with the classical algorithm, this dynamic probe station selection algorithm selects less probe and reduces the cost of probe selection while keeping up with the detecting effects in the dynamic network virtualization environment.
In design of real-time communication systems, the Worst-Case Execution Time (WCET) of software supplies pledge for the scheduling of the task, it is a creditable base that keeping the system running safely. With continuous growth of software scale and complexity of the hardware, the values of WCET estimated by determinate methods become more and more pessimistic, which greatly reduce the utilizing rate of the system resources . In order to improve the running efficiency of real time system, the article introduced a method of extreme value statistic in the estimation of WCET, and established the GPD model of WCET. The model was verified by experiments, the feasibility and the validity of this method was proven.
How to diagnose the fault of network is one of the problems in electric power data network. Currently, one of main factors that affect the accuracy of fault diagnosis in power integrated data network is the noise. However, there is almost no mention on the fault diagnosis method in the scheme, because it is difficult to improve the accuracy of fault diagnosis. A new fault diagnosis technique based on minimum entropy was proposed. Firstly, the information gain of each node is calculated according to the probability of node failure probability and the occurrence probability of each node. Then, the nodes are considered as suspicious nodes. Finally, the nodes are considered as nodes.
The industrial control system (ICS) security is closely related to the security of national critical infrastructure, so, more and more countries began to increase the importance of ICS. Aiming at the physical devices in ICS field control net, an innovative intrusion detection algorithm was presented to analysis and estimate whether the devices are in normal operation condition. This algorithm is designed to detect internal or external intrusion actions in ICS and complex attack by maliciously using normative control commands.
In order to improve the invisibility and robustness of digital watermarking algorithm, a new watermark was designed and embedded into large coefficients of low frequency of maximum entropy subband and small coefficients of low frequency of minimum entropy subband. And the strong directional sensitivity of extended discrete shearlet transform was introduced into digital watermarking as well. On this basis, a two-stage extended discrete shearlet transform of digital watermarking algorithm was proposed. Experiments show that the algorithm not only has strong invisibility, after adding a series of attacks, the watermark can still be extracted. The algorithm has strong invisibility and robustness.
In order to solve the problem of poor quality of information transmission in vehicular Ad hoc network, a local communication quality assurance clustering algorithm based was proposed on hierarchical structure. The vehicle nodes are divided into two tiers, the Ad hoc tier and peer to peer tier. The low tier nodes use the inter-vehicle communication mode, and high tier nodes use 3G, LTE and other more reliable and traditional communication modes. The algorithm is based on the classical weight clustering algorithm, and is improved with the local optimization. the maximum acceptable communication distance was introduced and a new cluster structure maintenance policy was proposed. Simulation shows that the proposed algorithm has higher clustering structure stability, higher packet delivery ratio and lower cost, compared to the classical clustering algorithm.
In order to set up an algorithm suitable for data distribution network of extensible messaging and presence protocol (XMPP) server cluster system with a relatively large number of sessions and the number of sessions, the weighted least connections algorithm was improved. This algorithm dynamically acquires the server's occupancy resources, and calculates the current load capacity and load level in real time. The servers' loading status is divided into three stages by the threshold values, and the servers are scheduled with two different algorithms. The algorithm can effectively improve the load performance of the server cluster.
A MapReduce based distributed computer telephony integration (CTI) system namely distributed computer telephone integrity (DCTI) was proposed to resolve the resource mutual exclusion problem of routing algorithm in a multi-skilled call center. The proposed system implements the distributed computing of the management and routing in CTI. It adopts the divide and conquer method to improve the routing algorithm and deploys the agents to the CTI nodes equally so that the routing can be computed separately in each node. The real-world application and experimental results show that the DCTI system can linearly distribute the business load of CTI to N nodes.
A top-N recommendation method-user class sparse linear methods (UCSLIM) based on sparse linear method (SLIM) was proposed. In order to improve the quality of recommendation, we learn from the idea of SLIM algorithm and collaborative filtering algorithm. The users are divided into different sets. So the correlation was analyzed between the user and the set of users and the correlation between user and user. Based on these two factors, UCSLIM was proposed. Experiments show that, compared with SLIM , UCSLIM can improve the quality of results. Furthermore, in order to improve the computational efficiency, the UCSLIM in Hadoop and Spark was implemented. Experiments show that the implementation by Spark has higher efficiency than that of Hadoop.
When the mobile devices provide services for a user in ubiquitous stub environment, some service transmission paths will be out of work because of device movement or limited power. The main purpose of the article is to seek a way for quick service recovery and reliable service transmission. This author put forward a dynamic service recovery mechanism which can maintain the data in the service transmission path flexibly. When the service transmission fails, the upstream recovery point directly resends the service data to its downstream recovery point. Simulations show that this mechanism can effectively reduce the request failure probability and the execution time.
An incentive mechanism based on credit and the balance of resources was presented. The incentive mechanism focuses on dynamic price of resources, as well as reasonable penalties for free riders. It maintains the balance between supply and demand. Simulations show that this incentive mechanism can not only effectively suppresses the free riding behavior, but also minimizes the resource price fluctuation, keeping the balance of resource supply.
Buffer overflow is a source of many security problems in C programs. A new tool named PathChecker to detect buffer overflows in C codes using dynamic symbolic execution method is proposed. PathChecker uses quantifier-free predicate formulas to describe the safety properties of buffer access operations and check these properties using a SMT solver. Experimental results show the effectiveness of this tool which is very easy to extend to check other safety properties.
In video stream applications, the image damage caused by encoding and transmission affects the quality of experience (QoE). The proposal presented here will provide a no-reference method to assess the video QoE based on the quantitative analysis of the image damage of video stream. The proposed method is a NR method and introduces the objective indicators, which can be used to represent the video stream image quality before network transmission, and to calculate the QoE levels. So it provides a reference for the assessment process without feedback and improves the accuracy of the assessment.
In smart grid, to meet high reliability requirements of power communication network, a path optimization method in power communication network based on particle swarm optimization was proposed. Based on the minimum construction cost, considering network reliability and service distribution factors, a path optimization problem model for power communication network was introduced. The path optimization model was solved by particle swarm optimization. Simulations show that the proposed method can improve the flexibility and comprehensiveness of path optimization to some extent, providing an effective path optimization scheme for power communication network.
Due to the growing demand of green network, to investigate new energy-saving methods that can enable a transition towards a greener long term evolution advanced (LTE-A) is important. A technology based on coordinated multiple points transmission(CoMP) was adopted to improve the coverage where the initial serving cells are dormant. At first, the network is divided into several independent clusters according to equivalent cell principle. Then the designed model selects cooperative cells and corresponding dormant cells. Finally, two indexes were adopted to evaluate the efficiency of energy-saving method. Simulations show that the optimal clustering radius is 1600 m since the dormant cell rate and the quality of service are taken into account together, which prove that the technology is effective to manage energy consumption.
A new solution for re-organization of the area was introduced into (ideally) equally sized rectangular zones upon peers leaving content-addressable network for distributed simulations (CANS) as a distributed infrastructure to run massive simulations (for example MMVE games or city traffic simulation). The peers handle the simulation of zones which is assigned to them. The zones should be split in such a way that there is as little communication between the peers as possible. Because a car or player needs in average the maximum time to cross a zone, a peer to peer tree structure (CANS tree) was introduced that helps to re-organize the area when peers leave.
According to the characteristics of gene expression data, a gene feature selection model based on improved information gain was put forward. The improved information gain was proposed to measure gene information quantity with sample weight and a no de-noising and de-noising gene feature selection model was established. The proposed model is compared with common gene selection model using four classifiers. Experiments validate that the proposed method can improve stability of feature selection algorithms without sacrificing predictive accuracy.
The article presented a data capacity estimation method for speech information hiding. It uses human auditory system (HAS) model to estimate the data hiding capacity of speech, or the maximum number of bits that can be embedded in speech. MPEG HAS model 1 was modified to estimate the just noticeable difference (JND) for FFT and power spectrum density coefficients. At the same time, a new embedded method that can reach the data capacity was introduced. The maximum number of bits was also calculated that can be embedded in speech to 2 787 bit/s when embedded speech is white noise.
Typical vehicle image feature will lost robustness and generalization ability under complex scene. To deal with this problem, sparse based vehicle images feature representation was introduced and a linear vehicles support vector machine classifier based on the sparse representation was proposed. Then, a framework of vehicle classification and recognition on surveillance video was constructed based on the background subtraction and sparse represented feature. Compared with traditional methods, vehicle images are represented as linear combination of the sparse coefficient of a learned dictionary (atom or base) in low dimension in our method, and sparse represented feature gains higher generalization capability with less computational complexity. Experiment shows that this work exhibits better classification accuracy and robustness under complex real environment with decrease image quality of low resolution, shadow and occlusion.
An increasing numbers of web information systems are deployed on the Internet to provide service, however, the web information system is facing various security threats, from physical security on bottom layer to communications and operations management, system security, application security and data security. The article gave out classifications of security threats faced by type of threats in web applications and set up grade for each threat according to its extent of danger, probability of occurrence and remediation. The article also uses fuzzy comprehensive evaluation to build a security analysis model aiming at constructing common analysis framework for web information system security assessment.
To meet the requirements of web application development for higher efficiency and lower cost, the agile development is widely accepted. But in traditional agile development procedures, the project process management and its technical framework are isolated, which greatly limits practical effects of agile development. An integrated web application framework for agile development with high adaptability and flexibility was brought forward in the article. The integrated development framework consists of both process management framework and technical framework and they are in close collaboration. Based on the principle of agile development, the process management framework defines goals and tasks which need to be done at each stage of application development process. The technical framework provides support for the whole lifecycle of web application development by using reusable components, templates and software frameworks. Furthermore, the technical framework was deployed on PaaS, which greatly improves the reuse efficiency. A series of application development using the framework specified in this article demonstrate the framework effectiveness.
The distributed energy is organized in form of microgrid, which is one of the hot topics in study of current smart grid. Collaborative coverage of sensors can conduct comprehensive monitoring for microgrid equipment and network status. It can provide a number of effective data support for power flow calculation and fault analysis, which is closely related to the stability of power grid. But the transmission for a large amount of data will speed up the energy consumption of the sensor nodes and shorten the life cycle of sensor network. A sensor collaborative coverage algorithm for microgrid monitoring was proposed. In different time period, this algorithm executes the construction and schedules the connecting collaborative cover to realize the efficient utilization of energy in the sensor node and prolong the life cycle of sensor network. Simulation shows that the collaborative coverage algorithm could prolong the lifecycle of the sensor network significantly with high efficiency.
The access points are thought of data gateways of power line communication network for connecting client with control center. To safely and effectively operate power system, it is necessary to research the optimal location of access points. In the article, a planning method was proposed when considering economics, reliability, N-1-resilience and network delay. In order to solve the planning problem, an immune algorithm was proposed to solve optimal location problem of access points. Simulations show that proposed method can perform an access point deployment plan effectively under conditions of different networks, with high flexibility.