最新刊期
卷 47 ， 期 8 ， 2013
- 摘要：A knowledge-based service composition algorithm is proposed to apply the techniques of service-oriented architecture including Web service and service composition in the area of the next generation Internet and the cloud computing. The algorithm consists of three key steps, i.e. connection matching between adjacent nodes, deleting broken nodes, and building service composition instance. All possible links between candidate primary service nodes are found and stored in an arc list at the first step. Then, the candidate primary service nodes that can not make a legal path are deleted in the second step. A service composition instance is built from the rest candidates in the step 3. The algorithm automatically assembles services without user's intervention during the service procedure, and builds the service composition instance in terms of a knowledge model and the connectivity between primary services. Test results show that the number of primary services and detection ranges can be effectively controlled.关键词：service oriented architecture;service composition;Web service1774|4|0更新时间：2025-05-08
- 摘要：The research on multi-sensor consistency measure usually focuses on the judgment from multi-sensor observations at a specified moment without considering the influence of time series, which leads to an incredible consistency measure result. Following the traditional consistency measure methods, a new method with higher reliability and better accuracy for sensor observations is proposed. The mid-value in the queue of consistency measure results is regarded as the robust estimate, and the variance in the queue is used to describe the stability of the consistency measure result to process confidence evaluation on consistency measure result. Simulations show that the proposed method is able to significantly improve the robustness of consistency measure results and eliminate the effects of unstable sensor performance by credibility weighting of the multi-sensor observation data, thus to provide the consistency sensor group for fusion estimation.关键词：consistency measure;confidence evaluation;data fusion1711|4|0更新时间：2025-05-08
- 摘要：A software aging detection method based on Bayesian evidence framework using least squares support vector machine(LS-SVM)is proposed to solve the uncertainties in software aging detection and analyzing, and software regeneration. The least squares support vector machine classifier is used to classify the data, so that the problems such as small sample of the data collected, the high-latitude, nonlinearity, and local minimum can be solved. Then, the Bayesian evidence framework is employed to get the optimal LS-SVM hyper-parameters, and hence, the learning accuracy and generalization ability of the classifier are improved. Experimental results in the state clear interval show that the probabilities of software aging given by the proposed method are all between 0.7 and 0.9, while the probabilities given by the high-dimensional model are 0 or 1. When the software aging is described by the probability granularity, the regeneration time can be more effectively selected; moreover, the uncertainty of the software aging can be further analyzed from the changes of the probabilities. Experimental and analyzing results show that the software health status described by the probability granularity is better in line with the practical status of software aging.关键词：software aging;least squares support vector machine;Bayesian evidence framework2052|4|1更新时间：2025-05-08
- 摘要：Measurement methods based on bi-directional flow model are proposed to investigate the symmetric characteristic of the non-business network traffics. The features of protocol, port distribution and flow size are extracted from host-level aggregated traffic to characterize users' interactive behavior and to find the origins of traffic symmetry. The analysis results using actual traffic traces collected from the campus network of Xi'an Jiaotong University show that 1% of the total hosts bear more than 90% of the forward UDP traffic, which results in the symmetry of total traffic. Compared with the traditional flow model, the proposed methods can quickly locate the hosts that are responsible for traffic symmetry, and are more suitable for traffic control and management in non-business networks.关键词：traffic measurement;non-business network;symmetric traffic;UDP traffic1813|4|0更新时间：2025-05-08
- 摘要：The gateway balance problem has the characteristics of multiple solutions. A bi-objective programming model is hence proposed to study the relations among the qualified rate of gateway balance condition, the gateway flow, and the fluctuation of generation schedule curve. Linear programming is used in gateway balance problem modeling. The first optimization objective of the model is to minimize the total penalty for violations of gateway balance conditions across the entire scheduling cycle, and the second one is to minimize the total penalty for fluctuation of generation schedule curve across the entire scheduling cycle. The linear weighting method and delaminating sequence optimization method are respectively used to solve the model. Numerical tests on an iron and steel plant show that the model effectively reduces the fluctuation of the generation schedule curve without increasing the total penalty for violation of gateway balance condition across the entire time horizon.关键词：demand response;gateway balance;bi-objective programming;linear weighting method;delaminating sequence optimization method1952|4|3更新时间：2025-05-08
- 摘要：To meet the requirements for vibration detection sensor in intelligent manufacturing and overcome shortcomings in the existing accelerometers including unsatisfactory performances, higher cost and bulky volume, a multi-flexure piezoresistive accelerometer is developed based on micro-electro-mechanical system(MEMS)technology. The proposed accelerometer introduces two tiny beams into the conventional quad-beam structure, which enhances the accelerometer's natural frequency without decreasing the sensitivity. The product of natural frequency and sensitivity is regarded as the evaluation factor to determine the sensor structural dimensions, considering the constraints form analytical optimization and manufacturing process. The sensor chip is fabricated by silicon etching, boron implantation, Al sputtering and anodic bonding. The experimental results show that the developed accelerometer possesses a sensitivity of 0.544 mV per gravity acceleration, a full scale accuracy of 1.76% and natural frequency of 13.61 kHz, and can accurately acquire the acceleration signal with different frequencies. Compared with the conventional quad-beam sensor, the comprehensive property of the proposed multi-flexure accelerometer is improved by 85%.关键词：micro-electro-mechanical system;accelerometer;natural frequency;sensitivity1820|4|1更新时间：2025-05-08
- 摘要：An advanced algorithm for delay-constrained Steiner tree is proposed to focus on the problem that the existing delay-constrained Steiner tree algorithms usually lead to high multicast cost and high time complexity. The proposed algorithm adopts the idea of path increasing in Dijkstra algorithm and the method of link sharing. It iteratively searches the node with the least feasible cost to the current tree and adds the destination node to the current tree through its feasible least cost path in the fast search stage. The missing destination nodes are added to the current tree through its least delay path in the exception handling stage of the algorithm. The delay-constrained Steiner tree is constructed through these two stages of the algorithm. Theoretical analysis, experimental results and comparisons with similar algorithms show that the proposed algorithm can construct multicast tree in lower cost and time complexity.关键词：Steiner tree;cost;delay-constrained;path increasing;link sharing1785|4|0更新时间：2025-05-08
- 摘要：The previous ciphertext-policy attribute based encryption scheme scarcely considers the significance of attributes. The concept of weight is thus introduced into the ciphertext-policy attribute based encryption scheme. The authority assigns different weights to attributes according to their importance in the system. The authority transfers the attribute set into weight attribute separation set according to the weight of attributes. Ciphertext-policy weighted attribute based encryption scheme is realized with linear secret sharing methods. And the security model of ciphertext-policy weighted attribute based encryption scheme is proposed. This scheme verifies the security against chosen-plaintext attack under the decisional bilinear Diffie-Hellman exponent(DBDHE)assumption in the standard model. Although the size of ciphertext and private key increases, the new scheme achieves fine-grained access control, and reflects the significance of attributes, which is more suitable for the practical applications.关键词：encryption;access control;attribute-based encryption;weighted attribute2608|4|10更新时间：2025-05-08
- 摘要：The concept of triangular fuzzy number is introduced into the game model to solve the problem of cannot making accurate judgments on both offense and defense payoffs in game analysis. The payoffs, which are difficult to be described with accurate numbers, are expressed with triangular fuzzy numbers, and the game algorithm based on triangular fuzzy matrix is thus proposed. The complexity analysis verifies the time complexity to meet the requirements of network security assessment. The strategy based on the algorithm can ensure the minimum income of attacker to approach to 14.44; and for the defense system, the best defense strategy that greatly enhances the host system security is to adopt Install Patches. Compared with the traditional security assessments following game theory, introducing the concept of the triangular fuzzy number facilitates suiting the applications and improving the accuracy and validity of assessments.关键词：security assessment;triangular fuzzy number;fuzzy matrix game;network security1645|4|5更新时间：2025-05-08
- 摘要：The technique of domain flux has been used by many botnets to avoid being blocked by domain blacklists. A new technique is proposed to detect botnets by analyzing the patterns inherent to domains that comprise alphanumeric characters and query behavior of hosts. The method analyzes failed domain queries through support vector machine(SVM)to identify suspicious compromised hosts. Clustering analyses are then performed to generate new successful domains and the groups of hosts that query these domains, and to examine if these host groups are composed of compromised hosts. Then, the command and control(C&C)domains and related IP addresses used by botnets are detected. Experimental results show that the accuracy of SVM prediction reaches more than 98.5% after training, and that the system can accurately detect compromised hosts and IP of C&C servers when DNS traffic from the ISP is monitored.关键词：network security;botnet;domain name;domain flux1719|4|0更新时间：2025-05-08
- 摘要：A solar radiation model with cloud influence(SRMCI)is proposed to consider the influence of cloud movement on solar radiation fluctuation for large-scale photovoltaic power plant. The model is based on the calculations of clear-sky solar radiation and cloud movement. The Navier-Stokes equations and the thermodynamic equations of cloud are differentiated for coupled map lattice to build the SRMCI by combining the clear-sky solar radiation model given by American Society of Heating, Refrigerating and Air-Conditioning Engineers(ASHRAE)and the attenuation model of solar radiation due to cloud droplets. Simulation results show that: 1)the proposed SRMCI model can efficiently analyze the stochastic characteristics of the solar power plant output; 2)the fluctuation of the total power output of the solar power plant is suppressed through aggregating power outputs of 50 units with different fluctuation; and 3)the attenuation of the total power output due to cloud is about 17.7%, and the fluctuation of the total power output is about 10.8% of the average fluctuation of the unit outputs.关键词：solar radiation;photovoltaic power plant;cloud influence;coupled map lattice;stochastic characteristics1691|4|3更新时间：2025-05-08
- 摘要：Character segmentation is a key technique for Uyghur handwriting recognition, but cursive characters and the phenomenon of stroke drift make the segmentation difficult. A new character segmentation algorithm based on multiple information fusion is proposed to solve the problem. Strokes of a word are extracted, segmented and clustered to get two types of sections: main and affix. The robust over-segmentation primitive sequences are obtained using fuzzy section matching to reduce the interference from stroke drift. Then, the matching information is estimated by constructing a matching position Gaussian model. The recognition confidence is converted from character classifier outputs by confidence transformation, and the semantic information is obtained by word data statistics. A character sequences Markov model is presented and the formula to calculate the posterior probability of a word is derived based on the Bayes criterion. The optimal path and the optimal segmentation result are achieved by weighted multiple information fusion. Experiments show that the proposed algorithm can effectively improve the accuracy and stability of character segmentation.关键词：information processing technology;handwriting recognition;character segmentation;Uyghur language;multiple information fusion1572|4|1更新时间：2025-05-08
- 摘要：A reconstruction algorithm with Bayesian compressive sensing for synthetic aperture radar(SAR)images(DLWT-TDC)is proposed to solve the problem that the dependencies of wavelet coefficients are not fully exploited by existing compressive sensing(CS)reconstruction algorithms. The new algorithm exploits both the interscale attenuation and the intrascale directional clustering property of the directional lifting wavelet transform(DLWT)coefficients. The DLWT is used for SAR image's sparse representation, and then, 3×5、5×3 and 5×5 neighboring blocks are used to design prior probability models with local adaptivity in both the direction and space. Then the Bayesian inference via Markov chain Monte Carlo sampling is used to recover the image's wavelet coefficients and the reconstructed image is generated in turn. Experimental results show that the DLWT-TDC achieves high reconstruction performance when the sampling percentage is in the range from 50% to 90%. Comparisons with the Bayesian tree-structured wavelet compressive sensing algorithm, which only uses the interscale dependencies, show that the proposed algorithm improves the peak-signal-to-noise-ratio by about 3 dB when the sampling percentage is 90%.关键词：synthetic aperture radar;directional lifting wavelet transform;sparse representation;Bayesian inference;compressive sensing1872|4|3更新时间：2025-05-08
- 摘要：A 1st-order transconductance-capacitance-resistance(Gm-R-C)complex filter for image rejection in low-IF wireless sensor network(WSN)receiver is proposed to reduce the power consumption of radio frequency receiver in WSN. The proposed cell adopts two fully differential Gm-cells with low power and R-C loads to perform low-pass filtering for the input I/Q signals, while the frequency translation is realized by two additional differential Gm cells through directly cross-adding relevant currents. Resistive source degeneration is adopted in the Gm cells to improve linearity. Based on the proposed 1st-order cell, a 4th-order Butterworth complex filter with center frequency of 300 kHz and bandwidth of 160 kHz is designed using the 0.35 μm CMOS technology. Simulation results under 1% I/Q mismatch show that the filter achieves an image rejection ratio of 50 dB, an in-band 3rd-order input intercept power of 25.1 mW, a pass-band gain of 18 dB, and an RMS voltage of input referred noise of 35 μV with current consumption of only 760 μA from a 2.7 V supply. All the simulated parameters achieve the system requirements of WSN with low power consumption.关键词：wireless sensor network;complex filter;radio frequency receiver;transconductance;image rejection2051|4|1更新时间：2025-05-08
- 摘要：A scheme to design observer with unknown input and unknown input reconstruction for Lipschitz nonlinear systems is proposed when the observer matching condition is not satisfied. An auxiliary output vector is constructed to satisfy the observer matching condition, and a high-order sliding mode differentiator with high-gain is designed to exactly estimate the auxiliary output vector and its derivative. Then, an adaptive robust sliding mode observer which complies with a robust sliding mode control law and an adaptation law is developed based on the estimations of the auxiliary output vector and its derivative, and an unknown input reconstruction method is derived without using the derivative information of system's output vector. The Lipschitz constant does not need to be known and is adjusted using the adaptive law. The method of unknown input reconstruction avoids the direct use of the derivative information of system's output. Simulation results show that states and unknown inputs can be gradually estimated by the proposed unknown input observer when the observer matching condition is not satisfied, and that the Lipschitz constant can be adjusted within 5 seconds by the proposed adaptation law.关键词：unknown input observer;unknown input reconstruction;sliding mode observer1893|4|3更新时间：2025-05-08
- 摘要：A likelihood ratio test using auxiliary particle filter(APF-LK)is proposed to improve the capability of detecting stealthy target in sky wave over-the-horizon radar(SKW-OTHR). The state-space model is used to describe the SKW-OTHR system, and the detection problem in SKW-OTHR is concluded as a problem of target detection in a nonlinear/non-Gaussian dynamic system. Then, the output of the APF, i.e., the un-normalized weights according to the predicted particles, is used to obtain approximation to the likelihood ratio in the nonlinear/non-Gaussian system. A target is declared to exist and the sate estimation is outputted when the approximated likelihood ratio exceeds a given threshold. Otherwise, no target is declared.Simulation results and comparisons with the state of the arts show that the detection performance of the APF-LK method are improved by about 0.5～1 dB.关键词：stealthy target detection;auxiliary particle filter;likelihood ratio test;sky wave over-the-horizon radar1747|4|3更新时间：2025-05-08
- 摘要：A new space shift keying(SSK)modulation based on antenna selection diversity, called ASD-SSK is presented to solve the problem that existing SSK modulations cannot achieve transmit diversity. ASD-SSK utilizes the wireless channels of different transmit antennas with different characters to construct a signal constellation. Then, the optimal antenna subset is determined by selecting the optimal constellation subset which maximizes the minimum distance between the points in the subset. The information is then transmitted by using the SSK modulation with the selected antenna subset. In the iteration process of selecting the optimal antenna subsets, the total antenna set is divided into two smaller subsets by separating the two channels that have the smallest distance. This iteration scheme can effectively reduce the complexity of antenna subset selecting in the ASD-SSK. Simulation results show that the ASD-SSK scheme outperforms the original SSK in achieving selection diversity, and that the more the transmit antennas there are, the bigger the transmit diversity is. The ASD-SSK achieves about 14 dB gains when there are 6 transmit antennas at 2 bit·s-1·Hz-1 and symbol error rate is 10-3.关键词：space shift keying modulation;transmit diversity;signal constellation;antenna selection1776|4|5更新时间：2025-05-08
- 摘要：A fast mode decision algorithm is proposed to reduce the complexity in high efficiency video coding(HEVC)encoder. The potential effects of frame texture and its related quantization parameter on the final decision of optimal coding unit(CU)modes is considered, and the average depth of the previous frame and the minimum depth of its related large coding unit(LCU)are extracted to estimate the minimum depth of collocated LCU in the current frame to skip partial larger CUs in mode decision process. Then the maximum depth for current CU is determined by calculating the parameters of motion vector difference and predicting residues so that the unnecessary mode decision of smaller CUs can be avoided. Experimental results and comparisons with the conventional HEVC show that the proposed algorithm for HEVC achieves an average bit-rate increment of 0.69% whereas the coding complexity has a significant reduction of about 51%.关键词：high efficiency video coding;fast mode decision;coding unit;quantization parameter1667|4|5更新时间：2025-05-08
- 摘要：To solve the problems in the existing protection for high voltage source converter high voltage direct current(VSC-HVDC)transmission lines, such as insufficient sensitivity for main protection and slow operation for backup protection, a novel pilot protection for VSC-HVDC transmission lines by identifying model parameters is proposed. In the principle, the external fault is equivalent to a positive capacitance model, while the internal fault is equivalent to a negative capacitance model. For a ±60 kV VSC-HVDC simulation model of 300 km cable lines, the identified capacitance is positive line-to-ground one, about 80 μF, when an internal fault occurs; the identified capacitance is negative shunt one, about -1 000 μF, when an external fault occurs. Internal faults and external faults can be distinguished by judging whether the identified capacitor is positive or negative. The results show that this principle, unaffected by transition resistance, line distributed capacitance and control type, can identify internal faults and external faults reliably within 10 ms under various operating conditions with sufficient sensitivity.关键词：voltage source converter high voltage direct current transmission;model identification;pilot protection;fault component1806|4|5更新时间：2025-05-08
- 摘要：To investigate the mechanism of partial discharge(PD)of insulation defects in gas-insulated metal-enclosed switchgear(GIS)under impulse voltage, time-frequency characteristics of optical signals and current signals of PD are analyzed with short time Fourier transform(STFT), pseudo Wigner-Ville distribution theory and Gabor distribution theory. The analysis reveals that: 1)The time-frequency characteristics of PD signals can be effectively extracted; 2)Gabor distribution of PD signals is endowed with the best time-frequency aggregation behavior without cross-interference items and reflects the most detailed characteristics of PD signals in time-frequency plane; 3)STFT of PD signals possesses the poorest time-frequency aggregation behavior and 4)Pseudo Wigner-Ville distribution of PD signals includes several inherent cross-interference terms. The time-frequency characteristics of the optical signals and the current signals of PD are different and the rising time of the optical pulse is less than that of the current pulse in time-frequency plane.关键词：time-frequency;partial discharge;impulse voltage;extremely uneven field1906|4|3更新时间：2025-05-08
- 摘要：A new kind of transformer oil-based nanofluids(NFs)with semiconductive ZnO nanoparticles is prepared to investigate the influences of adding nanoparticles on relative permittivity of transformer oil. How the NF relative permittivity depends on nanoparticles' volumetric concentration and environmental temperature is also discussed. A nanoparticle polarization model following Clausius-Mossotti equation is proposed. Experiments show that the ZnO NF relative permittivity linearly increases with nanoparticles' volumetric concentration and linearly decreases with temperature. The calculation with the nanoparticle polarization model coincides well with the experimental data. The further analysis for the proposed model suggests that NF relative permittivity is dominantly determined by ordinary transformer oil, while the higher relative permittivity of NFs than pure transformer oil mainly results from the inner polarization of nanoparticles.关键词：ZnO nanoparticle;transformer oil;relative permittivity;Clausius-Mossotti equation;nanoparticle polarization1931|4|2更新时间：2025-05-08
- 摘要：Conventional linear quadratic regulator(LQR)method is regarded as an unsatisfactory solution for voltage source inverter(VSI)systems because it can not ensure reference voltage command tracking. Although linear quadratic tracker(LQT)method can ensure command tracking performance, its control effect may be weakened when the system exhibits non-linear behavior because it can not eliminate steady-state amplitude and phase errors. This paper proposes a new controller based on state-feedback with proportional-resonant(PR)control for three-phase inverter system. Following redefining the LQR problem, this controller improves the capability of optimal tracking, which is placed within a general structure offered by the internal model principle(IMP)of control theory.The method solves these two drawbacks of LQR method in context of command tracking, and eliminates steady-state errors with good tracking performance as LQT. The simulation and experiment verify that the scheme is able to eliminate steady-state amplitude and phase errors and to provide nice dynamic and static characteristics. The total harmonic distortion of output voltage gets lower than 1%, and voltage unbalance factor lower than 1.5% with 30% unbalance load.关键词：proportional-resonant;linear quadratic regulator;internal model principle;voltage source inverter1812|4|8更新时间：2025-05-08
- 摘要：Focusing on higher computation cost and lack of real-time detection for all techniques based on traditional S-transform to identify power quality disturbances, a real-time approach combining fast S-transform with least squares support vector machine is proposed. The standard deviation of module coefficients, maximum module coefficient of each frequency band, and module coefficient corresponding to the rated frequency are extracted from the one-dimensional vector of the fast S-transform of the original power quality signals as features, and the least squares support vector machine based on optimized parameters and the minimum output coding is used to classify and identify the voltage swell,voltage sag, voltage interruption,spike,transient oscillation and harmonic waves. Compared with the traditional approach based on S-transform, the proposed approach reduces the tasks in both extracting features and training of the support vector machine classifier due to fewer training samples. The longer the duration of the voltage disturbance signal, the higher the saving efficiency. To the same accuracy, for the disturbance signal with a length of 1 024 points, processing time can be saved by 99%. The classification accuracy of this approach gets up to 98% with higher anti-interference ability.关键词：power quality;fast S-transform;support vector machine;real-time1696|4|0更新时间：2025-05-08
- 摘要：The experiment was conducted on an apparatus with the gas engine speeds of 1 400-2 000 r/min to obtain the performance of the waste heat utilization type heat pump driven by a gas engine at various speeds. The results show that the average primary energy ratio(PER)rose slowly first and then decreased rapidly as the engine speed increased. The system PER was higher than 1.34 in the test range and its maximum change amplitude was only 2.3% when the speed increased from 1 400 r/min to 1 800 r/min, indicating that the system was more efficient in this speed range provided the required load was met. The average waste heat recovery ratio of the system reached 83.5% and the ratio of waste heat to heating capacity increased with an increase in the speed in the test range. Although the proportion of waste heat dropped at the lower speeds, the increased coefficient of performance(COP)made compensation for the drop, resulting in the highest PER at about 1 400 r/min.关键词：gas engine heat pump;waste heat utilization;varied speed1750|4|1更新时间：2025-05-08
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