最新刊期
卷 41 ， 期 8 ， 2007
- 摘要：Focusing on the problem that current dynamic trust aggregation algorithms searching for feedback trust information is based on trust chain in broadcast way, leading to slow in convergence and bad in scalability, a new scalable feedback trust information aggregation algorithm is proposed, in which the concept and definition of direct trust tree(DTT)are presented. Based on DTT a novel aggregating algorithm of scalable feedback trust information is proposed, and the DTT is constructed according to node's direct trust relation. Then, the feedback trust information is searched by using DTT instead of in broadcast manner. Two new parameters, quality factor and distance factor, are introduced to adjust the scale of aggregating computation automatically. Simulation results show that the algorithm remarkably enhances the convergence of feedback trust information aggregating computation. Moreover, it has better detecting capability against malicious feedback actions and has stronger robustness when the ratio of malicious nodes is increased.关键词：trust information search;aggregating algorithm;direct trust tree;scalability4434|5|6更新时间：2025-12-08
- 摘要：Focusing on the requirements of dynamically organizing resources in dynamic, open, and distributed grid environment, an infrastructure for constructing grid testenvironment-grid testing engine is proposed, which supports dynamic deployment, update and execution of testing items as well as alarming and auto-handling based on the emergence category of fault. The test pressure of target service is controlled by using tokens and the load balance of distributed testing is realized by token migration. Experiments in ChinaGrid environment show that the impact of the test environment constructed by the grid testing engine on the host system performance is less than 1%,the environment can create test pressure in accord with demands, test resources and service exactly, and reflect the performance trend change.关键词：网格测试引擎;分布式测试;网格资源3269|6|1更新时间：2025-12-08
- 摘要：An iris recognition method is developed based on Log-Gabor filtering and feature fusion. Multichannel 2D Log-Gabor filters are employed to extract the iris features. To reduce redundancy of the Log-Gabor features, multiple Log-Gabor features in the same scale with different orientations are combined by using the magnitude information, and the fusion features are encoded based on the phase information.The similarity of two iris codes is measured by their weighted Hamming distance.The noise mask codes are adopted to reduce the interference of eyelids occlusion. In addition, a method for iris image quality assessment is presented,which can discriminate the images that are unsuitable for recognition.The approach can achieve lower equal error rate and lower false rejection rate under same false acceptance rate, and the size of the iris codes is only a half of the traditional approach. The experimental results show that the false rejection rates at the false acceptance rates of 0.01%and 0.1% are respectively decreased by 0.57% and 0.36%, the equal error rate is decreased by 0.25%, and the size of iris codes is decreased by 50%, compared to the results of the traditional Gabor approach.关键词：虹膜识别;纹理特征;加权海明距离;图像质量3266|6|0更新时间：2025-12-08
- 摘要：针对移动、协同计算中缺乏群组形成模型的问题,提出了一种多维策略的移动协同群组形成模型(FMCGM).首先定义了论域U和移动协同群组G,并构造了G的网络空间模型.依据G中成员之间的关系,将移动协同群组划分为实体型群组(WG)和兴趣型群组(IG),以此抽取影响WG、IG形成的主要因素,并以这些因素为基构造多维因素空间,进而将移动协同群组的形成问题归结为参与协作的移动用户在因素空间上的相似性判定问题,从而构造出FMCGM模型,最后给出了该模型的案例.实验表明,该模型能处理移动协作群体的复杂性、动态性问题,从而保证移动协同服务支撑平台具有较强的协作支撑能力.关键词：移动计算;协同计算;协同群组3061|4|1更新时间：2025-12-08
- 摘要：Aiming at the problem that when new storage nodes are added to a parallel storage system by using Round-Robin method, the rebalancing operation needs to move a large quantity of data among storage nodes and therefore consume plenty of system resource, a new data layout called ordinal-selection was presented. The data layout of parallel storage system was completed by using rebalancing operations of simulation data repetitiously so as to make the nodes extension of the system more easily. Furthermore, an optimized ordinal-selection layout was also presented to increase the system's parallel degree by changing the data selection rules. The theoretical analysis and experimental results show that for a parallel storage system employing one of these two data layouts, the rebalancing operation can achieve zero ineffectual-move-ratio, therefore the remove of the data can be decreased farthest and the system resource consumption is decreased.关键词：并行存储系统;数据分布;重均衡;轮转方式;按序选取2839|5|0更新时间：2025-12-08
- 摘要：For modifying the shape of Bézier curve, a class of quartic polynomial basis functions with two adjustable shape parameters is presented,which can be regarded as an extension to classical cubic Bernstein basis functions. A polynomial curve called cubic quasi-Bézier(cubic Q-Bézier)curve with shape parameters is defined to outperform general cubic Bézier curves with the inherent flexibility. The shape of the cubic Q-Bézier curve can be adjusted by altering the shape parameters when the control polygon remains unchanged. The shape modification of the cubic Q-Bézier curve by geometric constrains is investigated. A new method is presented by changing the shape parameters to satisfy the given constrains, and the corresponding simple computational formulae of the shape parameters with unambiguous geometric significance are proposed. Some practical examples verify the applicability.关键词：cubic Q-Bécubic Bézier curve;shape parameter;shape modification3061|5|10更新时间：2025-12-08
- 摘要：对于Bézier曲线的形状调整问题,给出了一组含有2个参数的四次多项式基函数,它是三次Bernstein基函数的扩展.基于该组基函数定义的带形状参数的曲线,称为三次拟Bézier(三次Q-Bézier)曲线,其优点是在保持控制多边形不变的情况下,可以通过改变形状参数来调整曲线形状.研究基于几何约束的形状调整,通过改变形状参数来满足给定的约束条件,得到形状参数简洁的计算公式,具有明显的几何意义.计算实例表明,该方法是有效的,可以广泛地应用于计算机辅助设计中对曲线形状调整.关键词：三次Q-Bézier曲线;三次Bézier曲线;形状参数;形状调整0|151|10更新时间：2025-12-08
- 摘要：提出了一种基于八邻域网格聚类的多样性XML近似查询算法.首先给出了支持XML文档间语义距离计算的3种编辑操作代价模型,再利用XML文档间的语义距离建立XML文档的向量模型并设计基于八邻域网格的XML文档聚类算法,进而利用聚类过程中得到的物理和逻辑聚类中心对静态有序选择算法的查询评估策略进行优化,这样做只需定位聚类中心所在组群的局部范围,并在该范围内进行目标查询,而无需遍历整个XML数据库,从而快速返回满足用户需求的查询结果.经汽车外形智能化设计实验表明,所提算法的查询速度比静态有序选择算法平均提高了3～4倍.关键词：多样性;近似查询;语义距离;八邻域;静态有序选择3254|4|2更新时间：2025-12-08
- 摘要：Focusing on the maneuvering target tracking problem in wireless sensor networks, a state space model for describing the maneuvering target acceleration is proposed.On the basis of the model,single and multiple target tracking algorithms based on particle filtering are developed, in which the approximate posterior probability distribution is acquired through searching a set of transmitted random samples in the state space, and the integral operation is replaced by sample's average value so as to obtain the minimum variance estimation. Simulation results show that in wireless sensor network environment, the maneuvering target tracking problem can be solved better by the proposed algorithm. The precision of velocity tracking and maneuvering tracking acceleration is increased by about 27% and 20% respectively compared to the traditional particle filtering algorithms.关键词：传感器网络;目标跟踪;粒子滤波算法3208|5|1更新时间：2025-12-08
- 摘要：To remove noise when extracting fetal heart sound from Doppler fetal heart echo signal, the threshold denoising method based on wavelet transform is adopted according to the signal features, and the denoising threshold and the estimation for original noise variance are investigated to modify the coefficient of threshold operators for different scales based on actual signal intensity, the noise variance and the number of decomposition layers. This method has been employed to process actual Doppler fetal heart echo signal, the result verifies that the method enables to heighten the signal-to-noise ratio by five times than the traditional filter and accurately calculate fetal heart rate.关键词：ultrasonic Doppler;fetal heart rate;wavelet transform;threshold denoising2884|5|4更新时间：2025-12-08
- 摘要：The singularity of a 6-PRRS parallel robot is studied based on Jacobins matrix. For forward singularity, the Jacobins matrix is obtained based on velocity projection, a new notion of spatial instantaneous axis is introduced, and the expressive form of the parallel mechanism singularity is given when it is generated. For inverse singularity, the parallel robot is divided into several series mechanisms, and the Jacobins matrix of these series mechanisms is solved by the exponential product equation and proved to be singular when the series mechanisms are singular. Based on forward or inverse singularity, a more special composite singular phenomena is proposed, which is generated when the forward and inverse singularities occur simultaneously under a certain spatial pose, and its possible existent form is given. The solving process of Jacobins matrix, the proving of matrix singularity and the description of the mechanism singularity provide a new and intuitional method for studying the singularity of parallel mechanism.关键词：机器人;雅可比矩阵;空间瞬时轴;指数积;奇异性2796|5|2更新时间：2025-12-08
- 摘要：基于免疫原理和Boosting机制,提出了一种模糊分类规则挖掘算法.该算法主要借鉴于自然免疫系统中的克隆选择原理,通过抗体种群的演化来优化模糊规则.模糊规则库通过增量的方式产生,算法每次运行得到一个规则.Boosting机制用于调整训练数据的权值,使得新生成规则集中于当前未被覆盖或误分类的数据实例.仿真实验表明,所提算法可根据规则的分类精度来调整训练数据的权值,促进了模糊规则之间的协作关系,避免了规则之间相互冲突,提高了系统的分类精度.关键词：免疫原理;模糊规则;分类规则;挖掘算法3096|4|2更新时间：2025-12-08
- 摘要：A new efficient traitor tracing scheme using bilinear mapping is presented in order to solve the user-key leaking problem in digital right management. The group-key distribution strategy with double master keys is employed in the proposed scheme to compute the decryption key of each user, and the encryption and decryption algorithms are constructed based on bilinear pairings on super-singular elliptic curve. The broadcasting center only needs to broadcast a controlling header with three group elements, and the authorized users can correctly decrypt the broadcasting information and recover the session key. The security analysis shows that the proposed scheme can efficiently resist the k-collusion attack and the anonymous single-user pirate attack under inverse Weil-pairing assumption and k-BDHI assumption, and in addition, it can be used to construct efficient public key traitor tracing scheme.关键词：traitor tracing;digital right management;bilinear map2905|5|1更新时间：2025-12-08
- 摘要：In order to solve the H∞ control problem for a class of Markov jump systems with saturated actuator, a design method based on dynamic output feedback controller of mode-jumping is proposed, and the H∞ dynamic output feedback controller is then designed on the basis of the guarantee that the closed-loop system is random stable. By transforming the nonlinear saturation constraint into the special linear constraint, the problem of solving the feedback controller with saturated actuator is converted to the design of controller with linear constraint. The stochastic stability is ensured by using the intersection of ellipsoid invariant set of different modes existing in the attraction domain of the closed loop system. In this case, solving controllers can be equivalent to a solvability problem of linear matrix inequalities. With the above method, the stochastic stability of the closed-loop system can be guaranteed by the designed controller which satisfies a certain level of H∞ disturbance attenuation. Simulation results demonstrate that the proposed method is valid and the system has strong restraint ability against disturbance.关键词：Markov jump system;actuator saturation;attraction domain;invariance set3243|5|1更新时间：2025-12-08
- 摘要：为了解决统计逐步判别分析法存在的问题,提出了一种基于粗糙集属性约简的统计判别分析方法.首先采用粗糙集属性约简进行变量筛选,这样可充分利用粗糙集属性约简不需要属性分布的先验信息这一特点,再对所选择的变量进行Bayes判别分析训练,建立判别函数或相应的后验概率函数,以解决选择变量过程中存储量较大且检验变量的重要性总体服从正态分布这一主观性假设等问题.通过对油气储层数据的实际分析表明,所提方法不仅易于实施,而且检验数据集的判别准确率高于统计逐步判别分析法,同时可节省预测成本,提高预测速度.关键词：粗糙集;属性约简;判别分析;储层预测3390|4|15更新时间：2025-12-08
- 摘要：Focusing on the problem of the friction disturbances in direct current(DC)servo system, a scheme of friction compensation with genetic algorithm(GA)is proposed. A friction model is established according to the friction characteristics of a DC servo system; then, the friction compensation is introduced to the feedback control structure of DC servo system to calculate the position error of the servo motor. Genetic algorithm is adopted to identify the friction compensation model, and to make the quantity of friction compensation approximates to the practical friction disturbance unceasingly, so that the influence of friction on the servo system is eliminated. Moreover, the objective function of genetic algorithm is selected according to the control demands in the transition process and steady state of the system. The friction compensation model obtained from optimized parameters compensates the low dynamic and static performance of the previous DC servo systems due to friction disturbance, and ensures that the servo motor has higher track precision. Simulation results demonstrate that, compared to the case without friction compensation, the adjusting time of rotating speed response of the DC servo motor is decreased by 0.12 s, and the static error is lowered by 1%, meanwhile the system has better restraint ability against friction disturbance and parameter robustness.关键词：直流伺服系统;遗传算法;摩擦补偿3306|5|2更新时间：2025-12-08
- 摘要：提出了一种基于阻抗相对变化的高压线路保护选相新原理,用作振荡期间的选相元件.对接地故障,利用零序、负序电流之间相位差进行分区,每个分区包括某相单相接地和另外两相短路接地两种故障,根据故障环上的测量阻抗为一恒定数值,而非故障环上的测量阻抗随振荡变化这一特征,来得到选相结果.本元件提高了振荡中不对称接地故障的选相速度,不受系统运行方式和分支系数的影响,且易于实现,在现有的微机保护装置中可以直接使用.动模数据仿真表明,新选相元件具有较快的选相速度,文中算例可以在60 ms内选出故障相.关键词：电力系统;线路保护;振荡;选相元件3043|4|7更新时间：2025-12-08
- 摘要：For protecting the privacy in the large-scale distributed database sharing and computation, a generic privacy-protecting computation model supporting the privacy-protecting data computation and analysis is proposed. The key of this model is the ‘privacy security module' which divides the distributed computation into ‘local computation' and ‘global computation'. By using homomorphic encryption, secure product protocol, random permutation and some other secure technologies comprehensively, the model achieves distributed data computations without compromising the privacy of both data record and sensitive intermediate computation result. Two privacy-protecting distributed algorithms based on this model, namely, the privacy-protecting distributed variance algorithm and privacy-preserving distributed k-means clustering algorithm, have also been introduced. The security and dynamic behavior analysis show that the proposed model and algorithms doesn't require any one-to-all interactions encryption, and the recovery computation only involves the changed nodes and the three nodes composing privacy security module when nodes change. So it's suitable for large-scale and dynamic distributed environments.关键词：privacy-preserving computation;homomorphic encryption;secure product protocol;random permutation3180|5|4更新时间：2025-12-08
- 摘要：以电力系统配置同步相量测量单元(PMU)个数最少为目标,全网可观测、系统有最大量测冗余度为约束,提出PMU最优配置模型.针对PMU价格昂贵,很难一次性安装上所有所需PMU的实际问题,提出系统不可观测度的概念,以每阶段安装相同个数的PMU能够最大限度地提高系统量测冗余度和最终完成安装后满足系统可观测的最优配置为约束条件,提出PMU分阶段的最优配置模型.在此基础上,采用改进自适应遗传算法求解此模型,保证全局最优.在陕西49节点实际电网的PMU安装地点优化计算中,基于文中模型的算法不仅给出了14个PMU、120个量测量的最优配置方案,而且给出了优化的三阶段安装步骤,目前此方案已在实际电网中得到应用.关键词：电力系统;相量测量单元;系统不可观度3|180|0更新时间：2025-12-08
- 摘要：Taking the full network observability of power system operation state, maximum state measurement redundancy and minimum number of PMU as objectives, an optimal PMU placement(OPP)scheme is proposed. Furthermore, aiming at the high price of PMU and limitations in the availability of communication facilities around the network, a novel concept of depth of unobservability is introduced, and its impact on the number of PMU placement is explained. Taking the maximum state measurement redundancy in every stage during installation and the OPP problem of total location of PMU as objective function, a staged optimal PMU placement(SOPP)model and an adaptive genetic algorithm for OPP and SOPP problems are presented. The algorithm based on thi s model provides a 14 PMUs plan with 120 measurements as well as three optimal steps during installation in Shaanxi 49-bus system.This optimal location of PMU has been applied practically.关键词：power system;phasor measurement unit;depth of unobservability3082|6|0更新时间：2025-12-08
- 摘要：Following the idea of passivity-based control and the theory of stator-flux-oriented control, and choosing the stator currents and the stator flux linkages(stator-flux frame)as the state variables of the electrical subsystems, a new interconnection and damping-assignment passivity-based controller and its stability region are presented. Based on theoretical analyses, it is concluded that describing induction motor model as an Euler-Lagrange system becomes unnecessary, and the mathematic definition of the decoupled dynamics condition is strict excessively. The effectiveness, stability and the satisfactory performance of the proposed controller, as well as the conclusions proposed are validated by the simulated and experimental results.关键词：inter-connection and damping assignment;passivity-based controller;induction motor;stator-flux-oriented controller;stability condition3151|5|0更新时间：2025-12-08
- 摘要：Focusing on the solution of the channel capacity for distributed Alamouti space-time code(DASTC)system, a novel method to derive the upper bound and the closed-form solution of the channel capacity for DASTC is proposed. Choosing the idle node closest to source node as relay node and utilizing the characteristic of DASTC that multiple nodes transmit information cooperatively, the wireless relay channel model is established for DASTC system. Using the max-flow min-cut theorem in network information theory, this method divides the channel model of DASTC into broadcast channel model and multiple access channel model. Sequentially, the upper bound of channel capacity and the achievable channel capacity of DASTC under fixed fading channels and random fading channels are derived. The channel capacity of DASTC based on different protocols can be effectively analyzed. The simulation results show that the channel capacity of DASTC based on decode-and-forward protocol and the channel capacity of DASTC based on amplify-and-forward protocol, which are obtained by the proposed method, are superior to Shannon channel capacity of the direct transmission, and are increased by 1 b/(s·Hz)and 0.4 b/(s·Hz)at high SNR, respectively.关键词：信道容量;分布式空时码;中继3434|5|2更新时间：2025-12-08
- 摘要：针对现有的丝网印刷碳纳米管薄膜需要各种后处理工艺才能改善其场发射特性的问题,提出了一种不需任何后处理的丝网印刷ZnO纳米锥的浆料配制工艺.该工艺以羧甲基纤维素为制浆剂,以水为溶剂,所制备的ZnO纳米锥薄膜表面上的有机浆料已基本分解,ZnO纳米锥在高温下既不会弯曲也不会团聚,且成本低,工艺简单.场发射特性测试表明,ZnO纳米锥与制浆剂质量比为3∶5的薄膜在电流密度为0.01 A/m2时,最低开启场强为2.25 V/μm,在4 V/μm场强下,阳极荧光粉的发光点亮度高且分布均匀.该工艺在ZnO纳米锥场发射显示器的制作中有很好的实际应用价值.关键词：ZnO纳米锥;丝网印刷;场发射;有机浆料;场发射显示器3235|4|0更新时间：2025-12-08
- 摘要：采用不同介电常数的绝缘材料,设计了基于表面闪络放电的触发型伪火花开关,通过实验发现,两种相对介电常数较高的材料（介电常数分别为1162和3 460）制作的沿面闪络触发器,具有结构简单、体积小、触发特性稳定等特点,用它们制作的触发型伪火花开关,放电电压在2～30 kV范围内,触发型伪火花开关的放电时延和时延抖动分别为81～39 ns、25～8 ns和77～35 ns、21～6 ns.对于耐受电压30 kV的伪火花开关,其最低可靠工作电压可分别低至134 V和128 V,相应的动态工作电压范围分别为0.48%99%和0.46%99%.关键词：触发型伪火花开关;时延和抖动;表面闪络放电2981|4|2更新时间：2025-12-08
- 摘要：A novel image multiscale geometric transform method is proposed. It is composed of pre-processing, directional filterbank and optimized directional wavelet transform. After pre-processing the image, the high frequency components are decomposed into several directional subbands by directional filterbank, and the modified optimized-directional wavelet transform is performed for each directional subband. The transform has the characteristics of multiscale geometric analysis of both Bandelet and Contourlet transforms, and it represents the edges and texture features more sparsely. The EBCOT coder and hard-threshold denoising are applied to the transform coefficients individually so as to realize efficient image compression and denoising and preserve the image details well. The experiments show that the proposed image compression and denoising method can significantly outperform those that are based on Bandelet or Contourlet transform in visual quality for the images with abundant edges and texture, and the peak signal to noise ratio is also increased by more than 0.1 dB.关键词：directional wavelet transform;Contourlet transform;Bandelet transform4487|5|2更新时间：2025-12-08
- 摘要：A multipurpose test-bed for inverse Brayton air refrigerator was rebuilt, in which the experiments were executed on the two key parts of the system, the turbo expander and the compact heat exchanger. The thermodynamic performances of efficiency, temperature drop characteristics, flow resistance, and refrigeration effect, etc. were analyzed thoroughly under design conditions, and examinations were done under overworking conditions. The test results show that the refrigeration capacity of this refrigerator is -73 ℃(with the cooling load of 250 W)～-120 ℃(with the cooling load of 50 W),the maximum temperature difference between system inlet and expander outlet is 150 ℃, and the expander efficiency can reach 60.5% while the heat exchanger efficiency reaches 97.5%. The minimum temperature of the system reaches -123 ℃, which meets the requirement of heat load of 5 W at -120 ℃. Through the test and analysis, the parameters influence relation and the parameters matching relation in high speed small turbo-expanders and compact heat exchangers are obtained.关键词：air refrigerator;turbo-expander;compact heat exchanger;experimental study3409|5|3更新时间：2025-12-08
- 摘要：The relation between scalp activity and cardiac automatic nervous system during a mental arithmetic(MA)task is explored with the power spectrum of electroencephalogram(EEG)and heart rate variability. The results show that heart rate increases(P<0.05), total power reduces(P<0.05), the normalized high frequency power component decreases(P<0.01)and the normalized low frequency power component increases(P<0.01)during MA task, so MA task weakens the cardiac sympathetic activity and enhances parasympathetic activity. And the average relative power in α rhythm of EEG decreases and the θ rhythm of EEG increases significantly(P<0.05). There are obvious correlations between θ rhythm of EEG for F8, FT8, C4, P4 and T8 channels and heart rate variability(P<0.05). It is noted that cerebral conscious activity increases and central decreases with parasympathetic activity decreasing and sympathetic activity increasing, and the pre-central, parietal lobe and temporal scalp influence heart rate by virtue of increasing sympathetic effects and decreasing parasympathetic effects, which plays an important role in cardiac autonomic regulation.关键词：autonomic nerve;heart rate variability;electroencephalogram;scalp;mental arithmetic task2998|6|1更新时间：2025-12-08
- 摘要：The application of support vector machine(SVM)for evaluation of the symmetry of elderly gait is investigated following the assumption that the determination of similarity between the lower limbs can be considered as a binary classification task. Adopting SVM to classify the right and left sides gait patterns of the elderly lower limbs during normal walking, the difference between the corresponding gait parameter curves can be determined effectively to assess the gait pattern symmetry. The bilateral kinetic gait data of 24 elderly participants are recorded by a force platform during normal walking. The cross-validation method is employed to evaluate the generalization ability of SVM, and three types of kernel functions(linear, polynomial and radial basis function)are validated. The experimental results demonstrate that SVM with polynomial kernel outperforms SVM with linear kernel and radial basis function in classification performance to identify the right and left sides gait patterns with an accuracy up to 88%. It is suggested that SVM serves as an efficient tool for evaluation of the symmetry of elderly gait to identify at-risk gaits in older population.关键词：步态分析;对称性;支持向量机;老年人2830|5|5更新时间：2025-12-08
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- 摘要：提出利用网格技术,将现有普通计算机计算资源联合起来,共同完成复杂的三维可视化任务.参与可视化任务的每个任务节点都提供一个网格服务,用户可以在任意的一个节点上提交任务.可视化网格平台根据资源信息列表,从使用状态动态变化的计算机当中选择出合适的机器作为任务节点参与可视化工作.测试结果表明,提出的网格平台可用于开发基于网格的医学图像归档与传输系统,实现图像后处理.关键词：计算网格;可视化;资源查找2866|5|1更新时间：2025-12-08
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