最新刊期
卷 44 ， 期 2 ， 2010
- 摘要：For nonlinearity and morbid state of image reconstruction for electrical capacitance tomography system, a radial basis function network image reconstruction algorithm is proposed to fulfill the requirement of flow regime identification. And the adaptive wavelet filter image reconstruction algorithm based on RBF, which belongs to a space-frequency analysis method suitable for image feature-enhanced, is emphatically analyzed to heighten the reconstruction accuracy. Undergoing multi-level wavelet decomposition of the image, the edge points are determined based on the neighborhood properties of each sub-band, the noise distribution in the space-frequency domain is estimated following the statistical characteristics and a self-adaptive edge enhancement gain can be obtained to reconstruct the image with the adjusting wavelet coefficients.The simulation results demonstrate that this algorithm enables to effectively implement image enhancement and edge detection, greatly improve the quality of reconstructed image and obviously reduce the distortion.关键词：image reconstruction;radial basis function network;wavelet filter;flow regime identification3291|4|3更新时间：2025-07-09
- 摘要：A P2P-based semantic Web services(P2PSWS)composition system architecture is presented to improve the scalability, reliability and stability of semantic Web service composition systems. The architecture combines the advantages of centralized structure and distributed structure, and distributes the function of UDDI to the local Web node, group Web nodes and public Web nodes. A location mechanism of semantic Web services is designed based on CAN(content-addressable network)P2P networks to ensure that each service is registered in one node of the public Web. The registration services of public Web nodes are divided by areas and shared by all nodes. The running of prototype system shows that the proposed structure helps to overcome the problem “the failure of a single node” on the traditional structures of public Web services and expands the capacity of P2P systems, and achieves an efficient ontology-based semantic Web services composition.关键词：semantic Web service;service composition;content-addressable network3426|4|0更新时间：2025-07-09
- 摘要：A hybrid-topology overlay network for large-scale application-level multicast-H-ALM is proposed. The overlay network is divided into two tiers by H-ALM. One is the backbone layer that has a tree-based topology; and the other is the branch layer that has a mesh-based topology. It is known that the stability of the pure tree-based topology is not good enough for distributing streaming data; and stream delivery over the pure mesh-based topology suffers from high delay yet. The H-ALM overcomes these shortcomings by combining the merits of the tree-based topology and the mesh-based topology, and optimizes the two-tier hybrid overlay network by considering the real-time status and network conditions such as the scale of the overlay, bandwidth capacity of nodes, the cumulative data traffic that each node relayed and received and so on. Therefore, the performance of stability and communication delay of distributing streaming data are improved. Experimental results show that the H-ALM achieves better stability than the tree-based overlay and lower transmission delay than the mesh-based overlay.关键词：application-level multicast;hybrid-topology;overlay network;stability;transmission delay3030|3|1更新时间：2025-07-09
- 摘要：To evaluate the quality of optimal solutions obtained by the ant colony optimization(ACO)algorithm in limited time, an improved ACO algorithm is presented on the basis of the ordinal optimization. An initial solution is selected using the blind picking rule, and the pheromone is initialized correspondingly. The number of iterations to achieve the optimal solution meeting the demand is then determined and is used as the termination condition of the algorithm. To make better use of the solutions obtained at each iteration, the first l solutions are employed to enhance search capability at the beginning phase of the algorithm. While the current optimal solution is used at the end phase of the algorithm to accelerate the convergence. The time complexity of the novel algorithm is not increased under the condition that ensures the convergence. Simulation results on the traveling salesman problem show that the proposed algorithm is superior to the max-min ant system in both the quality of solutions and the speed of convergence.关键词：ant colony optimization;ordinal optimization;blind picking;traveling salesman problem3359|4|6更新时间：2025-07-09
- 摘要：A novel similarity algorithm of extended topic map called ETMSC for multi-resource knowledge fusion is proposed to improve the drawbacks that the knowledge organization model based on metadata or traditional topic map can not represent knowledge multi-level and multi-granularity, and the low accuracy of existing similarity algorithms. Three principles of the correlation, levels corresponding, and the experimental determination in selecting threshold are presented. The algorithm combines the comprehensive information theory with the structure and semantic information of extended topic map. The syntactic matching, semantic matching, and pragmatic matching are comprehensively considered, in which not only the structural similarity of topic map elements are extended, but also the meaning and relevance in linguistic contexts are thoroughly taken into account. Topic map similarity criterions are related to a threshold, and the determination of the threshold is associated with the data sets. Experimental results and comparisons with the traditional algorithms that are purely based on the syntactic or semantic similarity show that the F-measure of ETMSC is improved by 9.2%-11.1%.关键词：knowledge fusion;topic map;similarity algorithm2723|4|6更新时间：2025-07-09
- 摘要：The Web services composition system with static configuration lacks of adaptive capacity to both the QoS variability of component services and the failure-prone environment. The static configuration can not reflect the dynamic evolution process of Web services composition when the number of component services increases continually. A method of QoS-aware and dynamic configuration for Web services composition is presented. The functional dependency relationship of Web services is described formally via an extended Petri net to form a configuration scheme. The configuration scheme is verified by two algorithms, which are used to confirm there are no loop dependency relationship and illegal end state in the configuration scheme. An optimal configuration selection algorithm is used to search the configuration with best QoS from the configuration scheme. Simulation experiments are conducted to compare the effects on the satisfaction rate of user request for service among the dynamic, static and random configurations.The results show that the QoS of composition service can be improved greatly by using the proposed modeling method and algorithms.关键词：Web services composition;optimal configuration;Petri net;adaptive system3394|4|1更新时间：2025-07-09
- 摘要：Concerning the advantage of particle filter in non-linear systems, and the problem of noise influence during the dissemination process, an improved particle filter algorithm with threshold de-noising is proposed. The idea of wavelet threshold de-noising is introduced into the particle filter, that is, after applying the wavelet packet decomposition on the signal, the coefficients that are greater than a certain threshold are reserved while other coefficients are set to 0. Thus, with the assistance of particle history information, the noise is reduced and the estimated filter state value is more accurate. Monte Carlo simulation results show that the particle filter with threshold de-noising can effectively reduce the filter root mean square error(RMSE)and improve filter accuracy, and that RMSEs in the corresponding linear and non-linear systems are reduced by 14% and 12% respectively.关键词：particle filter;threshold de-noising;nonlinear system3141|4|2更新时间：2025-07-09
- 摘要：In order to better meet customers' demands for the provision of web services, the semantic rules are used as the means to describe the service requests and the OWL-S service description language is used as service advertisement description language. The contribution of the semantic rules to the matchmaking results is reflected and the calculation of matching degree is facilitated by adding an impact factor to the rules in the service request description. An accommodation coefficient is introduced to judge if a given matching degree is enough to have a matchmaking success. Experiments using OWL-S TC V2 testing service set show that the proposed method increases the effective rate of recall and accuracy. Comparisons with the sub-sumption and the keyword matching based method in cases of k setting 2,5,8,10,15 and the maximum possible matching being 20 show that the top-k precision is promoted 15%,15%,9%,8%,2% and 5%,13%,30%,33%,30%, respectively, while the accurate rate remains stable at 95% or more.关键词：Web service discovery;semantic rule;precision3265|4|0更新时间：2025-07-09
- 摘要：An event-driven architecture for master-worker network computing is proposed to meet the needs in large-scale network computing systems such as high-concurrency, dynamic resource control and stability. The architecture combines the advantages of multi-threaded mode and event-driven mode, and a new strategy of thread management that is suited for master-worker network computing is derived based on queuing theory. The introduction of network queue extends the application domain of staged event-driven architecture from single host to wide area network environment, and the use of delay queue improves system response and reliability. The priority queue is designed for effectively supporting a variety of job scheduling mechanisms. Moreover, systems have the characteristics of modular construction and rapid development. Experiment results and the application of drug discovery grid with systems based on the proposed architecture show that the average job submission time is reduced from 1 850 s to 1 350 s and the average job processing time is reduced from 1 910 s to 1 420 s for 1 000 jobs, and that system resources have more rational use.关键词：master-worker paradigm;staged event driven architecture;dynamic resource control2996|4|2更新时间：2025-07-09
- 摘要：Since the existing anycast communication models can not achieve scalability and provide QoS guarantee simultaneously, an anycast communication model-SMA is proposed based on segmental measurement. The routing table is restricted by the competition among anycast group members, and only one winner can write its unicast address to the related routers. A method to estimate the variation upper bound of end-to-end delay is proposed. The anycast requests with QoS constraint are supported by measuring, sharing and estimating network parameters between routers and anycast members in a small region. Experiments on PlanetLab show that the proposed estimation method is accurate. Simulations in a nearly real Internet topology show that the SMA is efficient in the selection of best members and has good scalability and reliability as well.关键词：anycast;architecture;segmental measurement;QoS3320|4|2更新时间：2025-07-09
- 摘要：An object lifetime analysis algorithm is presented, which analyzes Java applications in just-in-time compiler in order to insert instructions to explicitly “free” objects into the applications, and reduces garbage collection overhead by assisting garbage collector in improving object allocation and reclamation. The proposed algorithm combines the live variable analysis and the pointer and escape analysis, and analyzes each method in Java applications only once. Moreover, the algorithm is inter-procedural, field sensitive and context sensitive, which can identify non-global objects and their dead locations in Java applications. Experimental results show that the proposed algorithm consumes 3.6%-5.3% of the total compilation time. The algorithm not only can identify the lifetime information of more objects than traditional ordinary escape analysis(such as that of Salagnac, et al), but also can determine the object dead locations with the basic block precision in control flow graph of a method; Moreover, the algorithm can explicitly reclaims more memory spaces in just-in-time compiler assisted garbage collection.关键词：object lifetime;live variable analysis;pointer and escape analysis;memory management optimization3526|4|1更新时间：2025-07-09
- 摘要：A novel contour mapping scheme based on Bezier curves for wireless sensor networks, SENS-T, is presented to solve the problem of energy limits in using wireless sensor networks to monitor environments. The scheme uses contours to represent the distribution of environment attribute value, that is, the contour is divided into pieces of Bezier curves, the shape and the position information of each Bezier curve is collected to one deputy node and is reported to the sink; and the sink uses the nodes coordinates and the received curve information to rebuild the contour curve. The number of report nodes is determined by the number of Bezier curve segments so that the traditional method that reports the information of all nodes on the contour is reformed. Simulation results show that the energy and bandwidth of network are saved efficiently by SENS-T, and a comparison with the traditional method at the same accuracy of counter mapping shows that the SENS-T saves approximately 45% network energy.关键词：wireless sensor network;contour mapping;Bezier curve;energy saving4055|4|0更新时间：2025-07-09
- 摘要：A novel distributive localization method using the angle of departure(AODL)is proposed to reduce the cost and complexity of existing localization methods for wireless sensor networks. The anchors emit time-division pilots to the network using multi-antenna system, and each sensor just utilizes single-antenna system to estimate the angle of departure(AOD)of the pilot, by which the sensor's position can be determined. The AODL only relies on radio transceivers, and the sensors estimate the angle information without the need of conventional multi-antenna system, so that the system complexity is greatly reduced. Moreover, the angle estimation and position calculation are conducted at each sensor in a completely distributed manner. The simulation results show that for a 100 m×100 m region, with the assistance of four anchors equipped with 3×3 uniform planar array, the average location error is within 1 m when the signal-to-noise ratio of each sensor is 15dB.关键词：angle of departure estimation;distributive localization;wireless sensor network3558|4|3更新时间：2025-07-09
- 摘要：An image coding algorithm combining the directional lifting wavelet transform(DLWT)and the trellis coded quantization(TCQ)is presented to overcome the drawback of JPEG2000 image compression standard in representing image edges. This algorithm firstly uses a rate-distortion optimization-based quadtree segmentation method to get the optimal transform directions, performs DLWT along the optimal transform directions, then quantizes the wavelet subband coefficients by TCQ, and finally encodes the quantization coefficients outputting the bitstream. Experimental results show that the proposed image coding algorithm outperforms JPEG2000 for the given test images up to 1.49 dB in peak signal-to-noise ratio and 3.98% relatively in multi-scale structural similarity index, and that significant improvement in the subjective visual quality of decoded images is also observed.关键词：directional lifting wavelet transform;trellis coded quantization;image coding3285|4|2更新时间：2025-07-09
- 摘要：A relay selection protocol with interference(RSI)is proposed to solve the problem that co-channel interferences affect the relay selection in cooperative wireless networks. The protocol minimizes the system outage probability, and selects the relay with maximum instantaneous end-to-end signal to interference and noise ratio to forward the source message. Moreover, the selection combining scheme is deployed at the destination to combine the direct transmission and relay transmission when the direct transmission is taken into account. This strategy can make full use of space diversity and decrease the system outage probability. Compared with the existing relay selection protocols, the proposed protocol does not need any information exchange between any two relays, and the data transmission is completed by competition. Thus, the proposed protocol has a low system cost and good practicability. Simulation results and comparisons with the max-min relay selection protocol show that when the number of relays is 4 and the outage probability is 10-2, the proposed protocol achieves about 3～4 dB signal to noise ratio gain in Rayleigh fading channels.关键词：cooperative wireless network;interference;outage probability;relay selection3345|4|0更新时间：2025-07-09
- 摘要：An analytical model of threshold voltage for the full depletion cylindrical gate metal-oxide-semiconductor field-effect transistor(MOSFET),is proposed to address the issue that polysilicon depletion effect is aggravated for deep submicron MOSFET. The potential Poisson's equation in the polysilicon depletion layer is solved to get the voltage drop in the polysilicon depletion layer, and the voltage drop is then used to modify the universal boundary conditions of the channel region. Then the 2D potential Poisson's equation in the channel is solved by using the superposition principle to construct the analytical models of surface potential and threshold voltage for the cylindrical gate MOSFET.These models are verified by device simulation software Sentaurus. The results show that the voltage drop in the polysilicon depletion layer would be larger and the corresponding threshold voltage shift would be more significant when the doping density of substrate is higher and the doping density of polysilicon is lower. Comparisons with existing models show that the precision of the derived analytical model is improved by more than 34%.关键词：threshold voltage;cylindrical gate;polysilicon depletion;surface potential2979|4|1更新时间：2025-07-09
- 摘要：An adaptive non-uniform quantization method is proposed to reduce the distortion due to the depth data quantization in free-viewpoint television(FTV)system using the ordinary non-uniform quantization method. The proposed method determines the valid depth sub-spaces according to the statistical distribution characteristics of the depth data. Then, these depth sub-spaces are finely divided to form an adaptive quantization look-table. Finally, the original depth data are adaptively quantized using the quantization look-table. Experimental results and comparisons with the ordinary non-uniform depth data quantization method show that the proposed method improves the quantization signal-to-noise ratio of the depth data by an average of 20 dB. Thus the adaptive non-uniform quantization method can significantly reduce the quantization distortion of the depth data, and benefits the high-accurate reconstruction of the depth data and the better subject visual effect of the synthesized image at the receiver of the FTV system.关键词：free-viewpoint television;depth data;depth sub-space;adaptive non-uniform quantization3405|4|3更新时间：2025-07-09
- 摘要：A novel algorithm(CS algorithm)for channel estimation and signal detection is proposed to resolve the problem of excessively high sampling rate of the ultra-wideband signals.The algorithm is based on the compressed sensing(CS)theory. The modulated signal is transmitted after random-filtering, and the received signal is sub-sampled. The mathematical model of CS is developed by cyclic convolution of the modulated signals, the random filter and the channel, so the basic pursuit algorithm can be utilized to perform the task of channel estimation and signal detection. Simulation results show that the number of the sampling data required by the proposed algorithm is only one-third or less of the number of the sampling data needed by the least squares algorithm, while the estimation performance is improved by 4.5 dB under the moderate signal-to-noise ratio(15～25 dB)condition, and that the original transmitted signals are correctly detected.关键词：ultra wide-band;channel estimation;compressed sensing;random filter3423|4|9更新时间：2025-07-09
- 摘要：A transmission line pilot protection principle based on the composite impedance of individual phase is proposed. The individual phase impedances are calculated from the fault total content differences of the voltages and currents at both terminals of the line, and then used for judging if the fault is occurs at the line.If the fault is outside of the protected area, the individual phase impedances just equal to the positive sequence impedance of whole length of the transmission line, while they will obviously differ from the determined value in case of the fault inside of the protected area,which refers an amplitude criterion. The proposed protection with independent phase selection possesses identity of reliable performance, sensitive operation, and strong adaptation. The EMTP simulation and the dynamic simulation test results indicate the effectiveness of the presented principle.关键词：transmission line;fault total content;pilot protection2748|4|4更新时间：2025-07-09
- 摘要：To improve the performance of the piezoelectric cantilever in energy harvesting, multiple piezoelectric cantilevers(PECS)were manufactured. The resonance frequency of PECS was analyzed by FEM and tested by experiments. It is found that the calculated results are in good agreement with the experimental results. Compared with a single piezoelectric cantilever, the PECS can effectively increase the band of resonance frequency. A maximal output power of 4.9 mW can be obtained from the PECS at 60 Hz across a resistive load of 820 Ω, which is enough for some wireless communication systems.关键词：multiple piezoelectric cantilevers;electrical energy generation;finite element analysis3358|4|16更新时间：2025-07-09
- 摘要：The mal-operation of pilot zero-sequence direction protection working on parallel lines is usually caused by the zero-sequence mutual inductance.By analyzing zero-sequence network of parallel lines, an inductance circuit model is established for the internal fault, and a novel zero-sequence directional relay based on model recognition is proposed for parallel lines. When the internal fault occurs, the model error is small and decreases quickly, and when the external fault occurs, the model error is large and oscillates.By computing the model error, the performance of the conventional zero-sequence directional relay is improved. The theoretic analysis demonstrates the validation of the new relay.关键词：model recognition;parameter distinguishing;transmission line;directional relay2973|4|1更新时间：2025-07-09
- 摘要：For six raw natural gases, the mixed refrigerant composition in propane pre-cooled mixed refrigerant(PPMR)process for liquefying natural gas is investigated under three kinds of high and low pressures of mixed refrigerant. It is found that the choice of mixed refrigerant composition depends on the specific heat(Cp)property of raw natural gas, while the high and low pressures of mixed refrigerant influence its composition and flowrate. Based on this, the energy consumption of PPMR process is compared for the above eighteen cases,and it is shown that the specific heat property of raw natural gas plays a key role in reducing the whole system energy consumption rather than the high and low pressures of mixed refrigerant or its composition. For a certain feed natural gas, the composition and pressure of mixed refrigerant should be selected appropriately to avoid the unnecessary increase of energy consumption.关键词：propane pre-cooled mixed refrigerant liquefaction process;raw natural gas;mixed refrigerant composition3349|4|9更新时间：2025-07-09
- 摘要：Aiming at the problem that frequent occurrences of ocular artifacts seriously interfere with the electroencephalogram(EEG)interpretation and analysis,a novel technique to eliminate ocular artifacts from EEG signals in real-time is proposed.The independent component analysis(ICA)is employed to decompose EEG signals, and these independent components features of topography and power spectral density are extracted. Specifically, a template-based isometric mapping(Isomap)algorithm is adopted to reduce the feature dimensionality.The low-dimensional feature samples are fed to a classifier to identify ocular artifacts components. The classification performances of several typical classifiers show that the template-based Isomap algorithm with the nearest neighbor classifier performs best. The experimental results demonstrate the efficiency for removing ocular artifacts with little distortion of underlying brain signals.关键词：Keywords:manifold learning;Isomap algorithm;electroencephalogram;dependent component analysis;principal component analysis3241|6|3更新时间：2025-07-09
- 摘要：The way by increasing the interface and compatibility between refrigerant and water to promote the rapid formation and growth of refrigerant hydrate is investigated. HCFC141b emulsion was prepared by high-pressure cutting method to increases the interface. The influencing factors, including emulsification time, bath temperature, HCFC141b content‘memory effect' and high-concentration surfactants, on induction time and supercooling degree of HCFC141b hydration are studied. Then, the thermodynamically stable HCFC141b micro-emulsion is successfully prepared with aid of T20/lecithin compound surfactants and T80 single surfactant to increase the compatibility of refrigerant and water. The characteristics of hydrate formation of HCFC141b micro-emulsion were revealed. The results have shown that low bath temperature,optimum HCFC141b mass concentration as well as long emulsification time are conducive to hydrate formation form HCFC141b emulsion; the ‘memory effect' has an important role in the promotion of hydration but does not accumulate; the surfactants T20, T80, SDS, SDBS and soybean lecithin have different influencing degrees on the promotion of hydration and there exists an idea concentration of each surfactant; HCFC141b can form hydrate rapidly and uniformly in the micro-emulsion. Compared with that of hydrate formed form HCFC141b emulsion, the induction time and supercooling degree of hydration form HCFC141b micro-emulsion are greatly reduced, which indicates that increasing the compatibility of refrigerant and water by preparation of micro-emulsion is a new way to promote refrigerant hydrate crystallization.关键词：HCFC141b hydrate;emulsion;micro-emulsion;induction time;supercooling degree3485|4|6更新时间：2025-07-09
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