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2009 Vol. 35, No. 10

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Grade-life model based on wavelet package and BP network for rolling bearing
Miao Xuewen, Hong Jie, Ma Yanhong
2009, 35(10): 1161-1165.
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Grade-life was used to describe rolling bearing-s service life, which means the entire service life is divided into four stages: good bearing condition, initial defect condition, damaged bearing condition and failure coming condition, and an assessment model was presented for bearing-s Grade-life. Signal feature extraction and pattern recognition algorithm are keys to construct the model. Vibration signals of the rolling bearing were analyzed, and the wavelet packet analysis theory was adopted to extract the Grade-life characteristics. Through signal decomposition and single reconfiguration with wavelet package to extract feature in every frequency bands effectively, and energy of various frequency bands acting as the life feature vector was input into the improved BP neural network to realize the mapping between the Grade-life vector and the Grade-life of rolling bearing, and the model in establishing the identification model by using bearing test stand run-to-failure data as learning samples was employed. The validity and creditability of model has been demonstrated by bearing test stand dates.
Knock signal analysis for gasoline engines based on discrete wavelet transform
Wang Yanyan, Yang Jianguo, Song Baoyu
2009, 35(10): 1166-1169.
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For the increasing of knock detection precision, the application of discrete wavelet transform(DWT) in the analysis of gasoline engine knock signal was studied. First, the knock feature was extracted from gasoline engine cylinder block acceleration signals by using DWT. Then, the parameter for evaluating knock intensity based on the energy of DWT decomposition detail coefficient was put forward. According to the character of DWT decomposition detail coefficient energy step change when knock took place, the method of confirming the knock threshold value was brought out, and the effectiveness of the method was also tested. The research results build the foundation of applying DWT to accurate and real-time knock control of gasoline engine. Further more, gasoline engine can work at slight knock zone by spark advance control, and the performance of gasoline engine can also be improved.
Truss topology optimization with uncertain loading scenarios
Li Dongze, Yu Dengyun, Ma Xingrui
2009, 35(10): 1170-1173.
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A new model of truss topology optimization (TTO) considering uncertain (in size and direction) loading scenarios was presented. The uncertain loading was modeled as bounded convex sets, and the uncertain model was transformed to a deterministic model. The TTO was formulated as minimization of the compliance subject to volume constraints, and the nature of this type of optimization is to minimizing maximum compliance in high dimensional ellipsoid. The traditional model considering convex sets is hard to solve, and TTO with convex sets was modeled as semidefinite programming (SDP) to overcome this special difficulty. The compliance both to given loading scenarios and a small occasional was simultaneously optimized in SDP model and optimum result showed that the compliance of the truss were slightly reduced respect to given loads, but the optimum topology of the truss is more robust and more practical than that with non-uncertain loading scenarios from the engineering viewpoints.
Computation of three-dimensional flow field in secondary gas injection for thrust vectoring nozzle
Liu Hui, Xing Yuming, Eriqitai
2009, 35(10): 1174-1178.
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The complex inner flow-field of the thrust vectoring nozzle based on secondary gas injection was numerically simulated using three-dimensional average Reynolds equations and the κ-ε turbulent models. The influences on the thrust vectoring efficiency and the thrust ratio of different injection parameters and the nozzle pressure ratio were analyzed and investigated. Results indicate that the effects of the position injection orifice, the injection angle and the injection mass flux on the vectoring angle couple each other.When the vectoring angle reaches its maximum value in design conditions, these injection parameters couldn-t reach their respective best value simultaneously.When the vectoring angle increases, The thrust ratio decreases and the thrust loss increases. The thrust vectoring of the rectangular injection orifice is better than that of the circular injection orifice. The vectoring angle increases with the decreasing of the nozzle pressure ratio.
Co-state estimation algorithm of the surface-to-air missile optimal trajectory
Li Jiafeng, Chen Wanchun
2009, 35(10): 1179-1182.
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As to obtain the precise optimal trajectory of the surface-to-air missile rapidly, a co-states estimation optimization algorithm was developed based on the Legendre pseudospectral method. The algorithm overcomes the shortcoming of the Legendre pseudospectral method such as there are too many optimization variables in the nonlinear programming (NLP) problem and the slow convergence rate. Additionally, on the premise of avoiding solving the two point boundary value problem (TPBVP), the optimal results satisfying the essential conditions could be computed rapidly. According to the characteristics of the midcourse trajectory optimization problem for a surface-to-air missile, the co-state estimation algorithm and the Legendre pseudospectral method were applied, and the results show that the algorithm takes on fast convergence rate and high optimization precision.
Safety-concerned longitudinal control strategy for takeoff phase of UAV
Zhang Ligang, Wang Yong
2009, 35(10): 1183-1187.
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In order to heighten the safety of unmanned aerial vehicle(UAV) taking off in atmospheric disturbance environment, a new safety-concerned longitudinal control strategy based on direct force control method was discussed as an improvement of the regular longitudinal control strategy for the takeoff phase of UAV. A combined filtering method was employed to resolve the acquisition of high-precision vertical speed signal of UAV, parameter selection and validation was carried out through frequency domain analysis method using the special testing equipment, the result verifies its feasibility and practicability, which satisfies the need of takeoff control. The nonlinear model of UAV was built in the Matlab/Simulink environment and then the flap control law was designed in accordance with the new control strategy. The simulation results show that the new control strategy is capable of enhancing the disturbance-resistance ability of UAV remarkably, thus ameliorating the safety performance of the takeoff phase.
Effects of channel orientation on fluid flow and heat transfer in a channel with angled ribs
Liu Chuankai, Ding Shuiting, Qiu Tian, Tao Zhi
2009, 35(10): 1188-1191.
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Numerical simulations of turbulent flow and heat transfer in a rotating radial outward flow passage with 60° ribs were performed. Three channel orientations were studied, that is, 0°,-45° and +45°. Effects of Coriolis and rib induced secondary flows were analyzed with the three dimensional simulations and the following conclusions were drawn: the combined effects of Coriolis and rib induced secondary flows largely depend on channel orientation. The 0° channel orientation produces largest heat transfer variation between leading and trailing edges, the -45° channel orientation gives the lowest overall heat transfer augmentation, while the +45° channel orientation has the highest overall heat transfer enhancement.
Adaptive model of rotor/turbo-shaft engine
Zou Xianquan, Sun Jianguo, Zhang Haibo
2009, 35(10): 1192-1196.
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An adaptive model of rotor/turbo-shaft engine on board was constructed using Kalman filter. The state variable model of rotor/turbo-shaft engine was built through the data fitness method, and a Kalman filter was designed using the deterioration factors as augmented state variables. The Kalman filter can be utilized to predict the component deteriorations from the deviation of measurable parameters, which are used to trim the unmeasurable output parameters of the model on board so that it can adapt the actual engine. The digital simulation results show that the adaptive model on board is able to match the actual engine well. Meantime, the robustness and real-time of the adaptive model are also validated in the full flight envelope.
Effect of embedding nickel foam on solid-liquid phase change
Xu Weiqiang, Yuan Xiugan, Xing Yuming
2009, 35(10): 1197-1200.
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To improve the void distribution and thermal performance of phase change thermal storage devices, thermal storage containers embedded with nickel foam cores were designed and manufactured based on the theoretical research. Phase change experiments were carried out with those containers, as well as containers without nickel foam, and the temperature variations of containers were tested and saved using platinum resistance thermocouples (Pt100) and data acquisition modules (ADAM-4000). Void distributions of those containers were imaged by the computed tomography (CT) instrument after the experiments. The results of two kinds of containers were compared with each other, and the improvements of embedding nickel foam were testified both in void distribution and thermal performance of solid-liquid phase change process. The research findings could provide some values for the application of solid-liquid phase change thermal storage.
BBN-based fault localization technique
Liu Yongpo, Jin Maozhong, Jia Xiaoxia, Liu Xuemei
2009, 35(10): 1201-1205.
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Fault localization techniques help programmers find out the locations and the causes of the faults and accelerate the debugging process. The relation between the fault and the failure is usually complicated, making it hard to deduce how a fault causes the failure. At present, analysis of variance is broadly used in many recent correlative researches. A Bayesian belief network(BBN) for fault reasoning was constructed based on the suspicious pattern, whose nodes consist of the suspicious pattern and the callers of the methods that constitute the suspicious pattern. The constructing algorithm of the BBN, the correlative probabilities, and the formula for the conditional probabilities of each arc of the BBN were defined. A reasoning algorithm based on the BBN was proposed, through which the faulty module can be found and the probability for each module containing the fault can be calculated. An evaluation method was proposed. Experiments were executed to evaluation the fault localization technique. The data demonstrated that 0.761 in accuracy and 0.737 in recall on average were achieved by this technique. It is very effective in fault localization and has high practical value.
Fatigue property and its probabilistic character of S06 steel
Hu Yanhui, Zhong Qunpeng, Zhang Zheng, Han Bangcheng
2009, 35(10): 1206-1209.
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The fatigue property between 104~107 cycles of S06 steel, which is a new kind of precipitation-hardened stainless steel with high yield strength, was tested with PLG-100C high-cycle fatigue testing machine. With the decrease of stress amplitude, more fatigue crack initiated from subsurface. The fatigue life of specimens where fatigue crack initiates from subsurface is longer than that of specimens where fatigue crack initiates from surface at the same stress amplitude. To estimate the probabilistic character of fatigue property in high cycle range, the fatigue data of interior initiation was researched: maximum likelihood method and Kolmogorov test method considering life truncate data was used to research the distribution of fatigue life and result shows that fatigue life follows lognormal distribution in long life region; maximum likelihood method considering life truncate data was used to fit P-S-N curve; the P-S-N curve was used to discuss the distribution of fatigue strength in long life region.
Camera calibration with parallel lines
Ma Changzheng, Dong Mingli, Zhu Lianqing, Lü Naiguang
2009, 35(10): 1210-1213.
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To solve precision problem of the camera lens distortion in vision measurement, a new method for nonlinear distortion correction and camera calibration was presented. Considering the fact that a camera followed the perspective camera model if and only if the projection of every 3D line in space onto the camera plane was a line, the coefficients of radial distortion were calculated with the radial anamorphic model and linear characteristic. The distances from the points with tangential distortion and the ideal points to the principal point were equivalent, and the coefficients of tangential distortion were obtained with the ideal points gotten by imitating the straight line. The distortion coefficients were used to correct the distortion points, and the parameters of the camera were estimated. The experimental results show that the accurate and reliable calibration parameters were obtained.
Image mapping approach based on biharmonic spline interpolation concerning dot arrangement and multi-mapping
Lai Guojun, Shen Gongxin
2009, 35(10): 1214-1219.
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To obtain connection between dot arrangement on mapping board and image mapping error of digital stereo particle image velocimetry (DSPIV), five mapping boards with rectangular dot pattern covering aera of same size were used respectively to perform image mapping. Dot spacing in these dot pattern was equal in row and in column. A biharmonic spline function based on the Green function was employed as mapping model in this process. Statistic value of absolute differences between dot-center coordinates after mapping and their theoretical values and its standard deviation were calculated for comparison of image mapping errors. An image multi-mapping approach was also presented. Another image mapping was performed consecutively on the image obtained from the first mapping process. The experimental result shows that the image mapping errors decrease as the dot number on the mapping board increases and the image multi-mapping approach can decrease the mapping errors compared to those of single mapping, but at the cost of time consuming.
Numerical simulation of shock impact on material interface
Zhang Bin, Liu Yu, Wang Ge
2009, 35(10): 1220-1223.
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The key of numerical simulation of the problems of shock impact on interface is capturing accurately the material interfaces. The position of material interfaces were captured by level set, the parameter of ghost points were defined by modified ghost fluid method, accordingly the problem of multi-interfaces was split into several the problems of signal material interface. Based on the methods mentioned above, the numerical simulation of the series problems of shock impact on material interface were presented, and the evolvement of material interfaces were given. It is found that the strength of shock wave and the shape of material interface have great effect to vortex, whether or not the interface reverse depends on the density of two materials.
Parallel algorithm based on improved SSDA in TEM
Hu Kai, Zhang Xinyu, Yang Rui, Liu Deqing
2009, 35(10): 1224-1227.
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A new terrain elevation matching (TEM) method using sequential similarity detection algorithm (SSDA), which is an image matching algorithm was presented, while regarding the digital elevation model, height value and real-time profile data in TEM as searching image, hue value and template in SSDA respectively. The dynamic threshold sequence and the method of selecting random points in groups were described. A parallelism algorithm based on improved SSDA was designed and implemented with message passing interface(MPI). The experiment results show that the improved SSDA algorithm can effectively increase the matching speed and the precision, and the corresponding parallel program can also get good speed-up ratio. Therefore the problem of high time complexity and lack of real time feature in traditional TEM was solved to some extent.
Calculation method for airplane IR radiation and atmospheric transmittance
Mao Xia, Hu Haiyong, Huang Kang, Liang Xiaogeng
2009, 35(10): 1228-1231.
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The infrared radiation of airplane targets and the radiation attenuation of the infrared radiation in the atmosphere were researched. Based on the existing theoretical study and the structure of the airplane, the infrared radiation sources of the airplane were divided into three categories: fuselage, hot spot and plume. Furthermore, calculation approaches to the character of infrared radiation for the three radiation sources at different wave band and different angle were proposed. According to infrared radiation transmittance in the atmosphere, a calculation method for the transmittance of atmosphere was put forward at different wave length and different target distance, and then this method was compared with Lowtran7. Finally, the radiant intensity received by the IR detector was computed after atmospheric attenuation at different wave band.
FCD based information processing model in parallel road network
Zhu Tongyu, Guo Shengmin, Lü Weifeng, Wang Jifang
2009, 35(10): 1232-1236.
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Limited by the poor GPS locating precision, it is quite difficult to implement map matching and path deriving procedures in the parallel road network by FCD (floating car data) technology, which affects the traffic information accuracy directly. On the basis of existing FCD information processing framework, some approaches were applied to improve map matching performance. And then, the freeway and service road paths were both viewed as vehicle trajectories, so as to reduce the probability of inaccurate path deriving effectively. Finally, the evidential reasoning framework was introduced to address the information unlikelihood and information conflict issues after the path selecting strategy adjustment. Contrast experiment shows that the traffic information accuracy on freeway and service road was improved about 14.26% and 9.46% respectively after employing our modified model.
Efficient architecture design for AVS de-blocking loop filter
Liu Rongke, Yu Peng
2009, 35(10): 1237-1240.
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In order to meet the requirements in the real time decoding of high definition(HD) video, an efficient very large-scale integration(VLSI) architecture proper for de-blocking loop filter in audio video coding standard(AVS) was presented. The 8×8 blocks were divided into 4×4 blocks for filtering operations. After centralized process of 4×4 block boundaries, data and filtering operations were performed at the same time by improving filtering order. This architecture can increase the efficiency of pipelining and operating data in the SRAM, thereby highly reducing the total clock cycles of filtering process. Experiment results show that only 196 clock cycles are needed to finish filtering a macro-block for de-blocking filter in AVS. The processing speed increases by 50%. When the maximum frequency is 100 MHz, the real time decoding of HD video can be achieved in this architecture.
Optimization of machine layout based on genetic algorithm
Shen Jiangang, Wang Li, Qiu Peiqiang
2009, 35(10): 1241-1244.
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To solve the machine layout problem, a multi-objective optimization model was constructed. And a combination mutation strategy, combined with the best individual mutation and the random mutation, was designed to remedy the defects of the present genetic algorithms for site layout problems. At the beginning of combination mutation, the best individual mutation was executed. If a better individual was generated, the worst individual in current population was replaced by the new one. Otherwise, the random mutation was executed on a random selected individual. Based on the combination mutation strategy, an improved genetic algorithm was also proposed to solve the problem of machine layout. Simulation experiments prove that the combination mutation strategy achieves solutions not inferior to the solutions of the random mutation in obviously shorter time. A comparative analysis further verifies the efficiency of the proposed algorithm.
Improved ant colony algorithm for shortest path problem in time-dependent networks
Liu Yongqiang, Chang Qing, Xiong Huagang
2009, 35(10): 1245-1248.
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An improved pheromone update strategy suitable for time-dependent networks was proposed. Under this strategy, the residual pheromone of each road can accurately reflect the change of weighted value of each road. An improved selection strategy between adjacent cities was used to compute the cities- transfer probabilities, as a result, the calculation of algorithm was greatly reduced, and the compute speed was greatly increased. To avoid the algorithm converging to the local optimal result, the ant colony algorithm was combined with genetic algorithm. In this way, the solutions after each traversal were used as the initial species to carry out single-point crossover. An improved ant colony algorithm for the shortest path problem in time-dependent networks based on these improved strategies was presented. The results of experiment show that the improved algorithm has greater probability to get the global optimal solution, and the convergence rate of algorithm is better than traditional ant colony algorithm.
Concurrency control of collaborative assembly system under web environment
Jing Shikai, Li Liansheng, Liu Jihong
2009, 35(10): 1249-1253.
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Based on the analyses of collaborative assembly operations under the web environment, five types of concurrency assembly conflicts were summarized, which are the inconsistent results produced by multi-clients, multi-clients grasping the wrong parts simultaneously, multi-clients assembling the same parts or subassembly in parallel, feasible concurrent subassembly operations being prevented and conflicts of assembly constraints. A hierarchical hybrid concurrency conflicts control model (HCM) was proposed, comprising two control layers and integrating four kinds of concurrency control strategies. The two former concurrency conflicts were eliminated effectively with the concurrency control strategy based on global assembly sequence integrated in the upper control layer. The rest three concurrency conflicts were resolved by the serialization strategy of assembly operations, server-locked and client-unlocked strategy and the strategy of designing assembly constraints library respectively which were integrated in the lower control layer. Finally, a prototype system has been implemented to test the concurrency control strategies, and the results show that the system is flexible and efficient.
Approach to expert recommendation with multiple knowledge areas based on fuzzy text categorization
Li Ming, Liu Lu, Wang Jun, Huang Zhaodong
2009, 35(10): 1254-1257.
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Recommending an appropriate expert in knowledge management systems is an effective and efficient way to utilize tacit knowledge. To recommend the experts with multiple knowledge areas and identify the user-s knowledge needs completely, an approach to expert recommendation with multiple knowledge areas based on fuzzy text categorization was proposed. Firstly, fuzzy text classifier was constructed. An expert profile was built by classifying the newly registered knowledge artifacts fuzzily and with volume and time factors. Knowledge needs model was composed of explicit knowledge needs and implicit knowledge needs. Explicit knowledge needs was identified by analyzing the browsing logs. Implicit knowledge needs was measured by the entropy of the explicit knowledge needs. Expert was recommended based on the matching degree of expert profile and the user-s knowledge needs model. The proposed approach was developed and was used successfully in the knowledge management system. The approach was proved to be applicable.
Dynamic quality planning in product development
Dai Wei, Tang Xiaoqing, Wang Meiqing
2009, 35(10): 1258-1262.
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In order to facilitate product development under dynamic manufacturing environment, methodologies and technologies were developed to support dynamic quality planning. A dynamic quality planning model (DPQM) for dynamic product development was proposed based on quality activities. The attributes of quality characteristics (QCs) were divided into five aspects for analyzing their evolution during the dynamic product development. The quality objectives were identified through the analysis of the specifications and engineering requirements of QCs at a specific product life cycle stage, followed by classification of quality operations according to their effects on the QCs. A dynamic mapping algorithm between quality objectives and quality operations for configuration of quality activities was presented, together with mathematical model of goal programming for quality planning. The framework for the use of the proposed methodology to solve the problem of measurement quality planning in aerospace manufacturing environment was reported, and the resulting optimization in the dynamic quality planning was discussed.
Optimization for CFRP pultrusion process based on genetic algorithm-neural network
Chen Xingkai, Xie Huaiqin
2009, 35(10): 1263-1267.
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According to the curing kinetics and heat transfer theory, the models of unsteady temperature field and resin curing for the pultrusion process of carbon fiber reinforced polymer (CFRP) were established. The finite element/finite different method associated with the indirect decoupling method based on ANSYS to simulate the temperature and degree of cure for CFRP pultrusion. The fiber Bragg gratings (FBG) sensor, encapsulated in an aluminum capillary, was utilized to real time monitor the temperature during pultrusion; and the final degree of cure was measured by Sorbitic extraction. The results show that the numerical model is reliable and correct. With the simulative results, the neural network was trained and predicted the degree of cure effectively. On the basis of the trained network, the genetic algorithm was used to optimize the temperature of die. It shows that the optimization method is effective and convenient.
Integrated design of aerodynamic and stealthy performance for missiles with non-circular cross section
Chu Liang, Ma Dongli, Liu Zhongtie
2009, 35(10): 1268-1272.
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According to the aerodynamic and stealthy performance requirements in non-circular cross section configuration design, and based on the concept of multi-objective optimization, the Pareto method and genetic algorithm were combined and tournament selective reproductive operator, Niche and Pareto filters technology were used to get the results with favorable distribution. Further more, response surface methodology was proposed to improve optimization efficiency.The aerodynamic performance of the missile was calculated by N-S equation numerical method, and radar cross section was calculated by physical optics and physical theory of diffraction. Compromise and optimization between these two objective functions, aerodynamic and stealthy performance of non-circular cross sections based on Pareto genetic algorithm, were realized, and the results are satisfactory.
Cournot oligopoly and its application: an extension to heterogeneous products with three participants
Wang Yuling, Chen Juan
2009, 35(10): 1273-1277.
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The concept on benchmark benefit of process innovation and the method of analyzing on oligopoly competition model with heterogeneous products were applied to extend the original study of two participants to the case of three participants in Cournot oligopoly. The gaming process of innovation was researched. Both the innovation level maximizing private profit and that maximizing social profit were brought out and the solving process was given. The main characteristics of the two optimizing process have undeniable connections. The innovation follower-s absorbing capacity was recognized as another factor influencing the imitated innovation, besides the knowledge distance between the innovation leader and its follower. The pure knowledge spillover was studied and absorbing capability was brought to help found another study model based on both study force and study capacity. Both the process innovation-s Cournot model and the innovation-s study model can extend the original models to real competition in most industries and manufacturing & innovation reality.
Game cross efficiency DEA based project review of equipment design
Wang Ke, Wei Fajie
2009, 35(10): 1278-1282.
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The multiple attribute comprehensive evaluation models which could deal with three types of index(benefit, cost, fixed) were constructed based on data envelopment analysis(DEA). The cross efficiency concept was introduced to link the self-evaluation with peer-evaluation of decision making unit(DMU) for solving the problem that optimal weights of the DEA based multiple attribute comprehensive evaluation model are non-uniform. A new game cross efficiency concept was combined with the DEA based model to deal with that optimal weights of the DEA based model are non-unique. The game cross efficiency concept, in which each evaluated DMU is seeking to maximize its own efficiency under the condition that the cross efficiency of the other DMU does not deteriorate, enhanced the discrimination and rationality of the evaluation results. The DEA based model was validated by a numerical example and was applied to the project review of equipment design which indicates that the method is efficient in solving the project evaluation, rank and selection problems.
Extracting thematic communities from Wikipedia
Yu Yang, Lin Zhangxi, Xia Guoping
2009, 35(10): 1283-1286.
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The current search module in Wikipedia has low search efficiency due to the search method, which is built on simple keywords matching. To improve the efficiency of knowledge retrieval from the Wikipedia spheres with more accurate links among them, the algorithm named term distance based on linkage (TDL) was proposed. TDL defines a new measure of distance between two keywords, which reorients and organizes those keywords into clusters. It is based on link structure analysis underpinned by computational models. The mechanism of ranking and recommending was imported. The experiment, which based on the snapshot of Wikipedia (May 2009), indicates that TDL would significantly increase the accuracy of knowledge retrieval in Wikipedia and this new algorithm can improve the users- satisfaction by 7% compared with the present one.

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