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15 September 2008, Volume 29 Issue 9 Previous Issue    Next Issue
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7D planning of product design and 1+3+X integrated design method based on system engineering Wen, Bang-Chun (1) 2008, 29 (9):  1217-1223.  DOI: - Abstract ( 221 )   HTML   PDF (2123KB) ( 665 )   Based on the systematic engineerings, a new theory and method are proposed for product design. The whole design method is divided into three phase, i.e., general planning, implementation and quality assessment. In the first phase the seven basic factors should be comprehensively planned for product design: conception, environment, process, objective, contents, methodology and, the quality assessment. During implementation the product design should be done according to the 1+3+X integrated design method, where the 1 implies that a product should be designed with its function optimized and the 3 mean that the method of design should integrate organically the dynamic, intelligent and visual optimizations together. The X reflects a special design method that is required to meet the special conditions necessary to a product. In the final phase the quality of the product designed should be assessed by way of theoretical analysis and testing or user's commissioning. References | Related Articles | Metrics

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Synchronization and stabilization of a large-scale system composed of coupled lorenz systems Liu, Xin-Rui (1); Zhang, Hua-Guang (1) 2008, 29 (9):  1224-1227.  DOI: - Abstract ( 280 )   HTML   PDF (206KB) ( 474 )   The synchronization and stabilization issues are investigated for a large-scale system, which is composed of N identical Lorenz systems and they are coupled together with the first state variable of each subsystem. When uncontrolled, the sufficient condition of synchronization for such the large-scale system is derived by choosing an adaptive feedback gain equation. And if choosing an appropriate controller, the large-scale system can be stabilized. Such a controller is composed of two components, i.e., the state feedback controller is simple and easy to implement, and the other one relates to coupling coefficient. As a result, the final expression is in the terms of the Linear Matrix Inequalities (LMIs). A simulation example is provided to illustrate the design procedure of the proposed method and its feasibility and effectiveness. References | Related Articles | Metrics

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Robust and reliable adaptive control of a class of uncertain switched fuzzy systems Zhang, Le (1); Yang, Hong (2); Jing, Yuan-Wei (1) 2008, 29 (9):  1228-1231.  DOI: - Abstract ( 246 )   HTML   PDF (181KB) ( 553 )   A model of a class of uncertain switched fuzzy systems is developed, in which each and every subsystem is uncertain and fuzzy, and the robust stabilization of the uncertain switched fuzzy system is studied. When the upper bounds of external disturbances are unknown and the actuator seriously failed insomuch that its undamaged parts are unable to keep the system stable, a robust, reliable and fuzzy adaptive controller is built using the switching technique and multiple Lyapunov function method to enable the relevant closed-loop system to be uniformly ultimately bounded for all possible uncertainties and all actuators of which the failure is permissible. Moreover, the switching law is designed to enable an uncertain switched fuzzy system to be uniformly ultimately bounded. Simulation results showed the feasibility and effectiveness of the method. References | Related Articles | Metrics

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Nonlinear networked control system based on TrueTime E, Da-Zhi (1); Xue, Ding-Yu (1); Wei, Ling (1); Pan, Feng (1) 2008, 29 (9):  1232-1235.  DOI: - Abstract ( 503 )   HTML   PDF (550KB) ( 982 )   A nonlinear networked control system based on TrueTime was proposed in view of that the nonlinear systems are often involved in uncertainties, complex architecture and difficulty in modeling and simulating under network conditions. Based on the Matlab/Simulink modularized TPCS (two inverted pendulums coupled by a spring) modeling in combination with the TrueTime communication network, the uncertainties due to the object to be modeled and the network-induced time delays were both processed synthetically by a robust controller we designed. The simulation results showed that the proposed system not only reduces the complexity of nonlinear system modeling but also provides the reference for the research on dynamic behavior of a nonlinear system with networked control system architecture. References | Related Articles | Metrics

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State feedback control of a class of nonlinear singular systems Yang, Guang (1); Zhang, Qing-Ling (1); Guo, Li-Xin (2) 2008, 29 (9):  1236-1239+1244.  DOI: - Abstract ( 233 )   HTML   PDF (243KB) ( 546 )   The problem of control of a nonlinear singular system that is non-minimum phase is discussed. The state space of a nonlinear singular system is derived by an algorithm. Then, a synthetic output function is reconstructed, which is statically equivalent to the original one and allowing the arbitrary assignment of the zero dynamics of the state-space realization so as to enable the state space to be in minimum phase. And the state feedback is put into effect for the minimum phase system thus obtained to realize the state feedback for nonlinear singular system. The proposed method was applied to the SIR epidemic model with Logistic growth control problem for the purpose of eradicating the epidemic. Simulation results showed the validity and effectiveness of this method. References | Related Articles | Metrics

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Moving vehicle tracking based on multi-resolution optical flow and multi-scale corner detection Liu, Meng (1); Wu, Cheng-Dong (1); Zhang, Yun-Zhou (1); Guo, Li-Feng (1) 2008, 29 (9):  1240-1244.  DOI: - Abstract ( 365 )   HTML   PDF (1182KB) ( 1175 )   A multi-resolution optical flow tracking algorithm based on wavelet pyramid is proposed, since the LK (Lucas-Kanade) algorithm for sparse optical flow cannot steadily and rapidly track the moving objects. By virtue of the idea of multi-resolution tracking and relevant computation, the algorithm decomposes the displacement of the object within the wavelet pyramid to enable the displacement to meet the requirement of the LK algorithm for tracking accurately the rapidly moving objects. Extracting the feature of moving vehicles, multi-scale Harris corner detection is proposed to adapt to the complicated traffic situation, thus solving the problem that the conventional Harris corner detection which may neglect corner points and their non-uniform distribution. Experimental results show that in this way the corner points are always steady and reliable when a vehicle is steering and moving, or the camera is zooming in/out, and the tracking algorithm proposed can provide an accurate and real-time match for the feature points. References | Related Articles | Metrics

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Induction motor parameter identification based on celestial system particle swarm optimization algorithm Li, Dan (1); Gao, Li-Qun (1); Huang, Yue (1); Wang, Ke (2) 2008, 29 (9):  1245-1248.  DOI: - Abstract ( 244 )   HTML   PDF (1025KB) ( 622 )   Aiming at the problem that the particle swarm optimization (PSO) algorithm tends to precocious convergence, a new algorithm of celestial system particle swarm optimization (CSPSO) is presented. With reference to the celestial system model in astronomy, the CSPSO algorithm divides the population into multiple independent celestial systems of which each and every one orbits in space in accordance with its own rules. The chaotic optimization is introduced in the later half of the algorithm to get the globe optimum solution. The CSPSO algorithm was applied to the identification of induction motor parameters, and the simulation results showed that it has higher identifiability parameters than GA and PSO algorithms. References | Related Articles | Metrics

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Conjunctive query answering to fuzzy description logic f-DLR-Lite∩ Cheng, Jing-Wei (1); Ma, Zong-Min (1); Yan, Li (1); Wang, Hai-Long (1) 2008, 29 (9):  1249-1252+1256.  DOI: - Abstract ( 288 )   HTML   PDF (2244KB) ( 959 )   The current research progress and shortages of the conjunctive query answering to description logic are analyzed. Based on the description logic DL-Lite and fuzzy set theory, a new fuzzy description logic f-DLR-Lite∩ is presented to represent and process n-ary relation and allow the concept conjunction to occur in the left-hand of inclusion axioms, with its forms of syntax, semantics and knowledge base all given. A new fuzzy query language to which the query threshold is compatible with user-defined weight is presented, and its conjunctive query procedure and algorithm are given over the f-DLR-Lite∩ knowledge base. Then, the complexity of the algorithm is analyzed with the FOL (first-order logic) reducibility of the procedure discussed. The f-DLR-Lite∩ can make up for the insufficiency of knowledge representation and reasoning by classic DLs, and the extended query language can express users' intentions more precisely and reasonably. References | Related Articles | Metrics

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Design and implementation of the algorithm to search mesh in hydropower simulation Zhao, Hai (1); Li, Zhan-Xu (1); Song, Chun-He (1); Jiang, Wei-Wei (1) 2008, 29 (9):  1253-1256.  DOI: - Abstract ( 283 )   HTML   PDF (960KB) ( 516 )   Considering the electric circuit in the abstract and making it an abstract graph in the category of the graph theory, the problem of searching mesh in the circuit is transformed into that to search the minimum independent closed loops in the abstract graph, to which the consistency between mesh and the minimum independent closed loops has been verified. Then, based on the breadth-first search algorithm of graphs, breadth-first based automatic search algorithm namely BSA for the minimum independent closed loops is given with its basic principle and procedure described. Simulation results showed that the algorithm is available to search precisely and efficiently all of the minimum independent closed loops in a graph at high running speed with small memory space occupied. So, it can fully meet the real-time requirements for minimized internal storage. References | Related Articles | Metrics

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Off-line optimization of fixed priority scheduling in hard real-time environment Luo, Ding-Ding (1); Zhao, Hai (1); Sun, Pei-Gang (1); Lin, Kai (1) 2008, 29 (9):  1257-1261.  DOI: - Abstract ( 263 )   HTML   PDF (1524KB) ( 692 )   The RM algorithm has widely been used in hard real-time environment, mainly due to its simple implementation mechanism and low scheduling overheads. However, the heavy system overheads resulting from the highly frequent occurrences of preemption under heavy workload are characterized by the fixed priority scheduling of the RM algorithm. So, a method is proposed to reduce the occurrences of preemption in running due to the scheduling by RM algorithm via optimizing the attribute by off-line computation of task set, thus reducing the relevant overheads. Simulation results show that the occurrences of preemption and relevant overheads in real-time systems can be reduced efficiently by the method proposed without extra scheduling overheads. References | Related Articles | Metrics

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LQI-based evaluation model of wireless link Zhu, Jian (1); Zhao, Hai (1); Zhang, Xi-Yuan (1); Xu, Jiu-Qiang (1) 2008, 29 (9):  1262-1265.  DOI: - Abstract ( 244 )   HTML   PDF (310KB) ( 1852 )   The evaluation of wireless communication link is crucial to the design of upper layer protocols of wireless sensor networks. Based on the statistical analysis made for a great deal of sampling values, a link evaluation model in terms of the Gaussian distribution is developed to infer the link quality or its condition between nodes from LQI (link quality indicate) values which the model is able to recognize. The model is verified and the results show that the model is extensible, i.e., it may provide the valuable reference for not only the application of wireless sensor networks, but also the simulation study on upper layer protocols. References | Related Articles | Metrics

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Characteristic analysis of internet topology by multiple measurement points Li, Chao (1); Zhao, Hai (1); Zhang, Xin (1); Ge, Xin (1) 2008, 29 (9):  1266-1269+1278.  DOI: - Abstract ( 224 )   HTML   PDF (414KB) ( 611 )   With the giant data samples authorized by CAIDA, the structural property of Internet topology was analyzed. Sampling biases caused by single point were first presented with the structural characteristics of network topology measured by multiple points analyzed empirically. The results indicated that the real network topology is characterized by power-law distribution and the power exponents decrease gradually with the weakened impact of sampling biases. Then, an analysis is made for the spectral density distribution of network topology to compare the spectral density in the scale-free graph based on BA growth model. It was found that the result is distinctly different from that of a real Internet topology. A conclusion is therefore drawn that the Internet is inconformable to the scale-free graph based on BA growth model. References | Related Articles | Metrics

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New selection method by bandwidth mean shift and its application in segmentation of lung nodule Sun, Shen-Shen (1); Li, Hong (1); Kang, Yan (1); Zhao, Hong (1) 2008, 29 (9):  1270-1273.  DOI: - Abstract ( 215 )   HTML   PDF (309KB) ( 870 )   To solve the segmentation problem of the blurred image edge and the connection of lung nodule to peripheral tissues, a new selection method is proposed by adaptive bandwidth mean shift and its mean shift is applied to nodule segmentation. Comparing it to the selection method by bandwidth on the basis of statistical analysis, it has the advantages of low complexity at time cost and getting correct bandwidth adaptive to actuality. According to the principle of bandwidth selection, the initial parameters of bandwidth are determined, and the most stable scale criterion of multi-scale filtering clustering theory was used to determine the optimal parameters of bandwidth. The proposed method was evaluated and tested for the clinical chest CT images including the nodules of different types, such as the ground glass opacity, the nodules lung walls and vessels adhesion, and anisotropic nodules. The results revealed that the proposed method is successful in segmentating lung nodules. References | Related Articles | Metrics

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Low-complexity antenna selection algorithm based on complex householder-QR factorization Xie, Zhi-Bin (1); Wang, Jin-Kuan (1); Wang, Yun (1); Gao, Jing (1) 2008, 29 (9):  1274-1278.  DOI: - Abstract ( 254 )   HTML   PDF (1122KB) ( 809 )   Conventionally the antenna selection algorithm provides high performance based on minimum bits error rate (BER) in spatial multiplexing system, but it needs the multiplication of a mass of channel matrices with high complexity in computation. To solve this problem, a low-complexity antenna selection algorithm was proposed on the basis of symbol error rate (SER). Studying the approximate equivalent relation between the signal-to-noise ratio (SNR) at receiving end and system channel matrices, an antenna selection algorithm is proposed utilizing the complex Householder-QR factorization. The proposed algorithm provides the high performance close to an optimal one, and has lower complexity in computation than conventional suboptimal algorithm. Simulation results demonstrated that the algorithm proposed enjoys favorable performance at lower cost in comparison with other algorithms. References | Related Articles | Metrics

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Improved method to reduce PAPR of OFDM system and its performance analysis Zhang, Zhen-Chuan (1); Yang, Ming-Hua (1); Liu, Jiang-Ning (1) 2008, 29 (9):  1279-1282.  DOI: - Abstract ( 256 )   HTML   PDF (325KB) ( 1615 )   Due to its special modulating characteristics, the orthogonal frequency division multiplexing (OFDM) technique results in a high peak-to-average power ratio (PAPR). The high PAPR signal to power amplifier needs strict linearity, and it thus becomes the main obstacle for OFDM technique to be applied in practice. An improved SLM selected mapping method is therefore put forward to reduce PAPR of OFDM system. The phase sequence is required to be embedded in the check operators of the OFDM data block so as to avoid the data transmission rate loss and reduce PAPR more efficiently by clipping. A computer simulation was done with the improved method and the results proved that it can reduce the PAPR of OFDM system more than conventional SLM technique with no code errors increased. References | Related Articles | Metrics

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Effect of heat treatment process on microstructure and mechanical properties of TWIP steels Wang, Shu-Han (1); Liu, Zhen-Yu (1); Wang, Guo-Dong (1); Liang, Gao-Fei (2) 2008, 29 (9):  1283-1286.  DOI: - Abstract ( 305 )   HTML   PDF (699KB) ( 1666 )   The investigation of the solution treatment of hot-rolled TWIP steel of three different compositions (Fe-25Mn-4Si-2Al, Fe-30Mn-4Si-2Al and Fe-30Mn-3Si-3Al) revealed that prolonging the temperature holding time can increase the elongation with no obvious change found in strength. Because prolonging the holding time benefits both the generation of more annealing twins to increase their boundary areas and the increase in the number of CSL boundaries which are favorable for the resistance to intergranular corrosion, fracture and creep. Therefore, the mechanical properties especially the toughness of TWIP steels can be improved by way of controlling its heat treatment process to increase the number of CSL boundaries in original structure. References | Related Articles | Metrics

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Effects of high magnetic field annealing on recrystallization texture of cold-rolled IF steel sheet Wu, Yan (1); Zhao, Xiang (1); He, Chang-Shu (1); Zuo, Liang (1) 2008, 29 (9):  1287-1290.  DOI: - Abstract ( 254 )   HTML   PDF (786KB) ( 878 )   The effects of high magnetic field annealing on the recrystallization texture in the initial stage of recrystallization in as-annealed interstitial-free (IF) steel sheet were investigated by the SEM-EBSD analysis. The annealing was conducted in a 12-tesla magnetic field at 650°C which was held for 0, 10 and 30 min separately to obtain the partially recrystallized microstructure in samples. It was found that the {111}<112> texture component, as compared with other {111} texture components, was favored by the applied high magnetic field in the initial stage of nucleation and growth. References | Related Articles | Metrics

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Effect of air film on sump shape and ingot surface quality of Al-alloy during semi-continuous casting Qu, Fu (1); Wang, Xiang-Jie (1); Zhu, Qing-Feng (1); Cui, Jian-Zhong (1) 2008, 29 (9):  1291-1293+1302.  DOI: - Abstract ( 243 )   HTML   PDF (985KB) ( 666 )   Investigates the sump shape, contact level between melt and mould, forming position of initial solidified shell and depth of sump of 6063 Al-alloy during the semi-continuous casting with air film used. The results showed that in comparison to hot top casting the application of air film to the casting process can lower the useful heat sink intensity of the mould and heighten the contact level between melt and mould, at the same time the forming position of initial solidified shell lowered and relatively flat sump shape. The lowered position of initial shell results in reducing the backheating of ingot and eliminating the segregation and cold shuts, the surface quality was greatly improved. References | Related Articles | Metrics

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Study on the electrical conductivity of NdF3-LiF-Nd2O3 system melts determined by CVCC technique Hu, Xian-Wei (1); Wang, Zhao-Wen (1); Gao, Bing-Liang (1); Shi, Zhong-Ning (1) 2008, 29 (9):  1294-1297.  DOI: - Abstract ( 251 )   HTML   PDF (1041KB) ( 763 )   With AC impedance method used, the rational parameters of electrical conductivity of NdF3-LiF-Nd2O3 system melts measured by Continuously Varying Cell Constant (CVCC) technique was determined. It was deemed that the Z′ value in CVCC formula should be selected as the sum of the resistances of melt and both electrode and conductor by fitting on the Nyquist diagram. And reading the real part of the total circuit impedance at high frequency was also a rational selection. Then, the electrical conductivity of NdF3-LiF-Nd2O3 system melts was investigated experimentally to get the linear regression equation of the conductivity in relation to temperature and melt composition, i.e., k(S·cm-1)=-2.111+0.005323 t(°C)+0.03220 wLiF (%)-0.1026 wNd2O3(%). Analyzing the equation, a conclusion is drawn that the electrical conductivity of the melts increases with temperature and LiF mass fraction, but decreases with increasing Nd2O3 mass fraction. References | Related Articles | Metrics

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Multi-scale simulation of microstructural evolution in near liquidus semi-continuous casting Zhou, Zhi-Min (1); Lu, Gui-Min (2) 2008, 29 (9):  1298-1302.  DOI: - Abstract ( 261 )   HTML   PDF (1337KB) ( 473 )   The models of temperature fields and phase transformation of Al-Cu alloy were developed for its continuous casting, where the change in solid fraction is available to couple the macro-scale simulation with meso-scale one. The steady state temperature field was calculated by the extrapolated non-physical boundary we proposed in the near liquidus semi-continuous casting process. The average undercooling of the cells in liquid/solid phase transformation region was taken as the principal parameter to calculate the nucleation rate in the melt by virtue of Rappaz's model, thus avoiding the extra estimation of the nucleation of the core of continuous castings. The solidifying process of Al-(3.5-10)wt% Cu alloys was simulated during liquidus casting at a casting speed 2 mm/sec. As a commonly used Al-Cu alloy, the ZL201 alloy was also simulated and the result is consistent with experimental result. The calculation showed that the content of alloying elements has great influence on the semisolid microstructural formation. When the mass fraction of Cu is 8%-10%, a microstructure can be obtained with favorable grain size and its distribution. References | Related Articles | Metrics

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Welding properties of thick spoke steel for automobile wheels Ma, Hai-Tao (1); Wu, Di (1) 2008, 29 (9):  1303-1305+1333.  DOI: - Abstract ( 243 )   HTML   PDF (845KB) ( 531 )   To study the effects of microstructure of heat affected zone (HAZ) after welding, cold crack sensitivity and microalloying element on the welding properties of the Nb-microalloyed steel plates used for the specified thick spokes of car wheels, of which both the rolling and cooling processes were controlled, the cold crack sensitivity and hardening trend of the steel were evaluated by theoretical calculation. The steel plate was welded by DC argon arc process and the welding parameters were simulated just like what role they play in actuality. The microstructure of welded joints of steel plate were investigated by optical microscopy and EMS, as well as the mechanical properties by testers. The results showed that in the spoke plate the heat-affected zone (HAZ) tends to be small cold cracking and the Nb addition improves greatly the properties of HAZ with no obvious change in properties found in other zones after welding. It can thus be concluded that the thick spoke steel we developed has high weldability. References | Related Articles | Metrics

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Application of improvement neural network to defect prediction of continuous cast slab Li, Ying (1); Tan, Li-Hong (1); Li, Bao-Kuan (1); Liu, Huan (2) 2008, 29 (9):  1306-1309.  DOI: - Abstract ( 272 )   HTML   PDF (327KB) ( 918 )   The conventional back-propagation for neural network is improved by introducing the variable-step learning rate with a momentum term added in so as to prevent the network from error surge and accelerate its convergence rate. Then, the causes and influencing factors on the longitudinal cracks on slab surface in the continuous casting process are analyzed, and a prediction system of longitudinal surface cracks of slab is set up with the HP295 steel supplied by Meishan Steelworks as example, based on the improved BP neural network. It is found that the root cause of the longitudinal surface cracks on HP295 is the nonuniform distribution of the secondary cooling water. So, adjusting the proportion of the secondary cooling water is the efficient way to reduce the formation of the longitudinal surface cracks in practical production. References | Related Articles | Metrics

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Theoretical studies on fullerene C32's derivatives C32X2 (X=H, F, Cl, Br) Wang, Dong-Lai (1); Jiao, Zhi-Feng (2); Shen, Hong-Tao (1); Zhai, Yu-Chun (1) 2008, 29 (9):  1310-1313.  DOI: - Abstract ( 200 )   HTML   PDF (279KB) ( 471 )   Based on the B3LYP density functional theory, the 6-31 G*-base set of functions was employed to study the geometrics and electronic structures in equilibrium and vibration frequencies of the C32 fullerene and its derivatives C32X2 (X=H, F, Cl, Br). The calculation results indicated that the four structures are stationary points on the potential energy surface of C32X2 (X=H, F, Cl, Br) molecules among them C32H2 and C32F2 are more stable and they will probably be synthesized. The calculation of vibration frequency revealed that the stability of halide's derivatives decreases with the increasing atomic number of the atoms in halogen, among which the C-F bond shows the max. stabilizing energy. References | Related Articles | Metrics

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Study and application of generalized quality evaluation of products by combination weights and fuzzy matter element Liu, Jie (1); Li, Chao-Feng (1); Li, Xiao-Peng (1); Wen, Bang-Chun (1) 2008, 29 (9):  1314-1317.  DOI: - Abstract ( 288 )   HTML   PDF (302KB) ( 902 )   Based on the fuzzy matter element model and generalized quality evaluation indices, a relevant evaluation was done objectively and efficiently for products' overall quality/performance, where the index weights were determined by AHP in combination with entropy weight coefficients so as to exclude the influences from the difference between index units especially between the orders of magnitude of index values. Thus, the irrational outcome can be avoided by determining both index weights and performance indices. Taking a car as example, its overall performance was evaluated with the generalized quality evaluation using combination weights, and the results showed that the index weights are reasonably assigned with its overall performance evaluated properly and completely. The evaluation method can provide scientific reference for customers to select the products they desire and make the strategy for the enterprise to develop their products. References | Related Articles | Metrics

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Study on parameterized simulation process for complicated mechanism design Sun, Wei (1); Li, Chao-Feng (1); Liu, Jie (1); Wen, Bang-Chun (1) 2008, 29 (9):  1318-1321.  DOI: - Abstract ( 244 )   HTML   Structural parameters should be determined fast so as to complete the mechanism design efficaciously. A new method is therefore proposed to design complicated mechanism by a simulation with the parameterization as its core. It means that all the structural dimensions of a mechanism are completely parameterized and users can modify them, if necessary, to implement rapidly modeling/simulation. The connotation of parameterized simulation and its flow in application to complicated mechanism design are discussed in detail. Taking a parallel mechanism as example, the process proposed for parameterized simulation is studied with the software ADAMS used, including the analysis of mechanism, parameterized modeling, creating dialog and starting the menu and parameterized simulation. The results verify the efficacy of method. References | Related Articles | Metrics

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PCA-based integrative spectrum identification method Li, Yun-Gong (1); Zhang, Jin-Ping (1); Wu, Ning-Xiang (1); Liu, Jie (1) 2008, 29 (9):  1322-1325.  DOI: - Abstract ( 242 )   HTML   PDF (1382KB) ( 571 )   Reducing the computational complexity is indispensable for the pattern identification in according to the integrative spectrum data. A PCA-based integrative spectrum identification method is therefore proposed. It regards an N-point spectrum as a point in the N-dimension space and forms a data matrix by use of the known spectrum as samples. Then, after PCA, the number of directions of principal components satisfying the threshold values of information remaining to reduce the dimensions of high dimensional data. And the centers of projective points of various spectrum in low dimensional space are computed to obtain the corresponding data templates. In applications, the identification results are classified according to the criterion which implies the shortest distance. The results of numerical simulation and voice recognition reveal that the method proposed has stable performance with high accuracy of identification and may take effect in its applications. References | Related Articles | Metrics

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Stress intensity factor of double parallel thermal fatigue cracks Yan, Ming (1); Sun, Zhi-Li (1); Yang, Qiang (1); Shi, Yan-Yan (1) 2008, 29 (9):  1326-1329.  DOI: - Abstract ( 274 )   HTML   PDF (388KB) ( 567 )   FEM is proposed to solve the stress intensity factors of thermal fatigue crack networks are hard to solve, where those factors include several groups with two parallel cracks each and are due to the occurrence of shielding effect. The aim is to investigate the relationship between the shielding effect and the gap between cracks. The specific gap n, unshielded percentage s and crack length radio f of the thermal fatigue cracks are all defined, and it was found that the three factors are in a certain relationship with each other and irrelevant with the boundary condition and length of crack. The n-s-f relationship curves are given so that the stress intensity factor of the main crack can be deduced according to that of a single crack when the shielding effect occurs. Numerical example showed that the method proposed is correct and valid. References | Related Articles | Metrics

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Application of MRD to vibration control of parallel machine tools Hu, Ming (1); Guo, Cheng (1); Cai, Guang-Qi (1) 2008, 29 (9):  1330-1333.  DOI: - Abstract ( 312 )   HTML   PDF (844KB) ( 553 )   To improve the dynamic characteristics of actual structure of parallel machine tools, they are reduced with a viscous damping model based on dynamics, which is developed according to vibration theory. Analyzing the mechanism of damping vibration attenuation, it is found that only if the value of the ratio of the external excitatory frequency input to the natural frequency of machine tool structure exceeds a certain value, the peak values of both displacement and acceleration can be decreased simultaneously by the control of variable damping so as to control the vibration attenuation. The principle of semi-active control system to improve the dynamic stiffness of parallel machine tools is discussed, and the MRD is therefore proposed to improve their dynamic characteristics. According to the Bingham plasticity model for magnetorheological structure in combination with the features of parallel machine tools, a Hooke's universal joint was designed and made for MRD. References | Related Articles | Metrics

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Finite element analysis of metal cutting process based on LS-DYNA Su, Chong (1); Hou, Jun-Ming (1); Zhu, Li-Da (1); Wang, Wan-Shan (1) 2008, 29 (9):  1334-1337.  DOI: - Abstract ( 621 )   HTML   PDF (479KB) ( 1244 )   The finite element method is used with the software LS-DYNA to simulate metal cutting process so as to investigate how the stress, strain and temperature change in workpiece. The simulation results show that the chip formation process is actually a plastic deformation process in which the tool rake presses cutting layer material along a slope to form the shearing slip. The maximum effective stress fluctuates around a constant value during stable cutting, and the residual stress in formed workpiece surface results from the pressing force due to rounded cutting edge. The cutting heat is mainly kept in the chips, while the cutting temperature decreases gradually from the inner to the outer layers of chips. The method proposed, as an ancillary means to shorten the time for the lengthy and tedious experiments, will provide an effective way and theoretical reference for the study on the principle of metal cutting and design of the relevant technological process. References | Related Articles | Metrics

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Removing of polycyclic aromatic hydrocarbon from plant oil by advanced oxidation process Gong, Zong-Qiang (1); Hu, Xiao-Min (1); Xu, Xin-Yang (1); Li, Pei-Jun (2) 2008, 29 (9):  1338-1341.  DOI: - Abstract ( 348 )   HTML   PDF (383KB) ( 1279 )   Plant oil has the ability to remove high-concentration polycyclic aromatic hydrocarbon (PAH) from contaminated soil through leaching. To realize the further environmental removal of the PAH, two kinds of plant oil containing PAH were treated with the advanced oxidation process, i.e., the combination oxidation by ozone, hydrogen peroxide and ultraviolet radiation. The effects of some operational parameters on PAH removal were investigated, and the results showed that ozone has the ability to oxidize PAH in plant oil, and its oxidizability to anthracene/fluoranthene is higher than to phenanthrene. A highest PAH removal rate up to 81% is obtained in plant oil when treated with 10%-concentration hydrogen peroxide in combination with UV used at pH=3, and, under the same conditions, the PAH removal rate is 76.5%, that is fairly good for treating the plant oil with high-concentration PAH for 8 hr. References | Related Articles | Metrics

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Dynamic study on soil erosion in Fushun city based on GIS and RS Qi, Xiao-Jun (1); Wang, En-De (1); Jia, San-Shi (1) 2008, 29 (9):  1342-1345.  DOI: - Abstract ( 253 )   HTML   PDF (237KB) ( 700 )   The soil erosion in two years of the Fushun city was studied dynamically with RS data and empirical RUSLE on GIS platform. The results indicated that the soil erosion intensity of the whole city area in 1998 and 2005 included four levels from tiny to heavy erosion, and the area of eroded soil was about 49.11% and about 47.44% of the total area surveyed in 1998 and 2005, respectively, i.e., the annual mean eroded area was 242.96 t/(km2·a) and 263.31 t/(km2·a). The soil erosion was mainly at tiny, light and medium levels with a bit at heavy level. The eroded area decreased from 1998 to 2005 due to human activities and changing precipitation, but the erosion intensity became heavier. In view of the relation of soil erosion to slope, altitude and land utilization, the eroded area was mainly distributed on the 8°-15° slopes, and the land whose elevation is 200-1000 m. However, the forest area covered all the four levels from tiny to heavy erosion, which occupied about 53% and about 72.5% of the total eroded area in 1998 and 2005, respectively. References | Related Articles | Metrics

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Quick assessment of loading capacity of bridge by cracking characteristics Zhang, Wen-Xian (1); Liu, Xin-Liang (1); Luo, Bing (1); Li, Ming-Guang (2) 2008, 29 (9):  1346-1349.  DOI: - Abstract ( 450 )   HTML   PDF (960KB) ( 595 )   According to the structural cause of flexural crack in a simply-supported reinforced concrete slab bridge, how to assess its loading capacity quickly was investigated experimentally. With 5 rectangular RC slab beams as specimens, the destructive tests were carried out the way the multi-stage concentrated load was exerted at both the tripartite points of the span simultaneously. Then, the relationship was obtained, in between the maximum and mean heights of cracks, crack width and loading capacity. An empirical formula is thus fitted by means of regression analysis, with a quick assessment of loading capacity of bridge proposed by cracking characteristics. Comparing the values measured with the assessed results, the feasibility and reliability of the proposed method are demonstrated. References | Related Articles | Metrics

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Mesoscopic numerical analysis of reflective cracking in cape seal pavement under load Zhang, Jun (1); Zhu, Fu-Sheng (1); Wu, Ze-Feng (1) 2008, 29 (9):  1350-1353+1357.  DOI: - Abstract ( 308 )   HTML   PDF (422KB) ( 458 )   A mesoscopic numerical analysis was made with FEM for the main influencing factors on the resistance to the reflective cracking in Cape seal pavement under load, and the parameters of materials used were given through fitting optimization. The results showed that in Cape seal pavement the resistance to reflective cracking is high if the asphalt content is low in asphalt macadam, while low void has adverse effect though it is not great. The reflective crack is not easy to form and propagate when the pavement in the vicinity of bottom crack can be separating to a certain extent from the old pavement. The resistance to reflective cracking is high for thick pavement but, in view of an overall consideration, the paving thickness should not exceed 5-6 mm. The propagation of reflective cracking can be dampened if temping well the substrate of pavement, and the gap-graded asphalt macadam can decentralize the stress to dampen the formation and propagation of reflective cracking. References | Related Articles | Metrics

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Determining the values of two constants in Paris equation via uniaxial tensile fatigue tests of concrete Liang, Lei (1); Zhao, Wen (1); Li, Yi (1); Cheng, Yun-Hong (1) 2008, 29 (9):  1354-1357.  DOI: - Abstract ( 1108 )   HTML   PDF (1046KB) ( 1239 )   To determine the values of two constants C and m in Paris equation, generally a lot of parameters are to be determined or the data resulting from complex tests are to be analyzed. A new way is proposed to solve the tedious problem by the inversion of compressive strength of concrete so as to obtain the total area of initial cracks and pores. Then, the stress intensity factor is converted into the stress the specimens are undergoing according to the expression of stress intensity factor of circular crack in fracture mechanics. In such a way the values of C and m are given by the data resulting from the uniaxial tensile fatigue tests of plain concrete. The analysis shows that the values of relevant parameters change greatly with the stress level, and the value of C changes in several orders of magnitude even though the value of m changes in the same order of magnitude. It's found that the values of relevant parameters are comparatively reliable if the max stress level is equal to 0.7. References | Related Articles | Metrics

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Research on collaborative contracts with Bayesian updates Zhang, Cui-Hua (1); Wang, Shu-Ling (2); Yang, Bai-Qiang (1) 2008, 29 (9):  1358-1361.  DOI: - Abstract ( 275 )   HTML   PDF (1290KB) ( 463 )   A decentralized supply chain consisting of two independent roles is considered, i.e., the manufacturer and retailer. Constrained by a quantity flexibility contract, the retailer can reduce the uncertainties in demand by way of updating the demand forecast information in accordance to Bayesian procedure. A collaborative contract model with quantity flexibility is thus developed to stimulate both parties, with an optimum decision provided for the retailer to determine the upper limit of ordering quantity or ordering flexibility. The distribution of profits between both parties is also discussed. Simulation results indicated that the quantity flexibility contract based on Bayesian updates can improve the accuracy of demand forecasting and performance of supply chain operation. By negotiation and cooperation, both parties will attain win-win goal in accordance to the profit distribution coefficient which is accepted by both parties. References | Related Articles | Metrics

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Study on the assessment level of experts based on ideal point of linguistic assessment matrices Chen, Xia (1); Ma, Li-Hong (2); Chen, Yan (1) 2008, 29 (9):  1362-1365.  DOI: - Abstract ( 284 )   HTML   PDF (1115KB) ( 754 )   With respect to the problem of assessing level of experts based on the linguistic assessment matrices inform of preference information, an analytic method is proposed to define the linguistic assessment matrices with their natures revealed. Then, by defining the deviation distance matrices between individual and grouped experts' assessment decision matrices and positive/negative ideal points of alternative set, an analytic method is given to assessment level of experts based on TOPSIS (technique for order preference by similarity to ideal solution). A numerical example is given to illustrate the feasibility of the proposed approach which will results in more reliable and credible decision-making and can be taken as an alternative way to assess expert level. References | Related Articles | Metrics

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Existence and uniqueness of solutions to a class of nonlinear equations of population dynamics with random migration perturbation Sun, Tao (1); Jiang, Xiu-Qin (1); Duan, Xiao-Dong (2) 2008, 29 (9):  1366-1368.  DOI: - Abstract ( 254 )   HTML   PDF (281KB) ( 708 )   The existence and uniqueness of random integral solutions are proved to a class of m-accretive random evolution equations of population dynamics with random migration perturbation in arbitrary finite interval of time by using Banach's fixed point theorem of the nonlinear functional theory, which is the improvement of the results obtained by both Schauder's and Sadovskii's fixed point theorems. References | Related Articles | Metrics