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15 April 2008, Volume 29 Issue 4 Previous Issue    Next Issue
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DC chopper system based on fuzzy control Geng, Jia-Min (1); Zhang, Hua-Guang (1); Zhang, Hong-Jie (2); Liu, Xiu-Chong (1) 2008, 29 (4):  457-459.  DOI: - Abstract ( 216 )   HTML   PDF (269KB) ( 557 )   The principle of fuzzy control and fuzzy arithmetic of the Buck-type DC chopper systems are emphatically discussed for the DC-DC link in the micro-turbine power converter system. Fuzzy control rules are designed for the DC chopper system via describing the relevant physical quantities in fuzzy state. Deduces the fuzzy relation matrixes from the definitions of the membership functions in various states. Thus, the control strategy is formed in terms of fuzzy criterion. The effectiveness and reliability of the designed fuzzy controller for DC chopper system are verified by both laboratory experiment and prototype practice. References | Related Articles | Metrics

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Design of mixed H2/H∞ controller based on fuzzy hyperbolic model Yang, Jun (1); Zhang, Hua-Guang (1) 2008, 29 (4):  460-463+468.  DOI: - Abstract ( 215 )   HTML   PDF (183KB) ( 469 )   Based on fuzzy hyperbolic model (FHM), a multiple-objective controller design method is presented for a class of discrete-time nonlinear systems, where the FHM is refers to the descriptive definition of a class of nonlinear systems and the architecture of the FHM controller. This controller is essentially a fuzzy controller and also a nonlinear feedback controller featured with saturation. Design with the linear matrix inequality (LMI), the controller can guarantee the asymptotic stability of a closed-loop system and, a suboptimal gain matrix of the controller can be obtained by solving an LMI-based optimization problem to enable the closed-loop system to satisfy simultaneously both the upper bound of H2 performance index and H∞ norm bound γ. Simulation results showed the validity of the design method proposed. References | Related Articles | Metrics

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Optimal guaranteed cost control of uncertain fuzzy descriptor systems with time-varying delay Tian, Wei-Hua (1); Zhang, Hua-Guang (1) 2008, 29 (4):  464-468.  DOI: - Abstract ( 225 )   HTML   PDF (186KB) ( 646 )   An optimal robust guaranteed cost control method is proposed on the basis of delay-independent criterion for a class of uncertain Takagi-Sugeno (T-S) fuzzy descriptor systems with time-varying delay. A linear quadratic cost function is considered as the performance index of the closed-loop system. Then, the robust guaranteed cost control of the closed-loop fuzzy descriptor system is discussed. The sufficient conditions for the existence of robust guaranteed cost controller via state feedback are given in terms of linear matrix inequalities (LMIs). And the design of optimal guaranteed cost controller can be reduced to a convex optimization problem constrained by LMIs. The designed controller is able to not only guarantee the robust asymptotic stability of the closed-loop uncertain fuzzy descriptor delay system, but also provide a minimized upper bound of the guaranteed cost. A numerical example is given to illustrate the effectiveness of the proposed method and the perfect performance of the optimal guaranteed cost controller. References | Related Articles | Metrics

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Modified differential evolution algorithm and its application to optimization of fed-batch fermentation Niu, Da-Peng (1); Wang, Fu-Li (1); He, Da-Kuo (1); Jia, Ming-Xing (1) 2008, 29 (4):  469-472.  DOI: - Abstract ( 245 )   HTML   PDF (158KB) ( 795 )   To solve the feeding optimization problem of a certain fermentation process, a modified differential evolution (MDE) algorithm is proposed. Because the basic differential evolution algorithm becomes slower in the vicinity of the global optimum with low accuracy, a simplex acceleration operator is introduced to expedite the convergence speed of the algorithm. On the other hand, a chaotic migration operator is introduced to prevent the algorithm from prematurity, so as to improve the diversity of populations and enhance the algorithm's capability to rise above what a local optimal solution is available to do. For the constrained optimization problems, three criteria are selected to cause the optimal solution to satisfy constraining conditions. MDE was applied to optimize the feeding rate of a fed-batch fermentation process, and the result revealed that it improves the finished product output and that the algorithm is effective. References | Related Articles | Metrics

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Mathematical morphology based image detection for multi-scale structural elements Wang, Kun (1); Gao, Li-Qun (1); Guo, Li (1); Pian, Zhao-Yu (1) 2008, 29 (4):  473-476.  DOI: - Abstract ( 262 )   HTML   PDF (665KB) ( 779 )   The detection results of image edges are different morphologically for multi-scale structural elements. A new edge detection algorithm is therefore proposed introducing the structural elements of different scales, i.e., the small-scale structural elements are dilated to become big-scale ones, then they are synthesized in a weighting way so as to form the edge image. Simulation results showed that for the blurred images mixed with different noises in concolorous background, the more the frequency of dilation, the more complete and clearer the synthesized image with more exact details. Compared with other conventional edge detection methods, the algorithm proposed has the advantages of providing clearer edge contour, and insensitivity to noise when applying it to the images with expected PSNR (peak signal-to-noise ratio) values. References | Related Articles | Metrics

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Fusion-based algorithm of edge detection combining wavelet transform with morphology Ge, Wen (1); Gao, Li-Qun (1); Shi, Zhen-Gang (1); Sun, Qing (2) 2008, 29 (4):  477-479.  DOI: - Abstract ( 371 )   HTML   PDF (799KB) ( 634 )   An algorithm of edge detection is proposed combining wavelet transform with mathematical morphology and using a simple fusion strategy to locate image edges. In the wavelet domain the high-frequency sub-image edges are detected by solving the maximum points of local wavelet coefficient model to restore edges, while the low-frequency sub-image edges are detected by mathematical morphology. Then, both sub-image edges are fused according to certain rules and restructured through inverse wavelet transform. Experimental results showed that the fusion rules are simple with high generlizability, thus making the algorithm effective in noise control to regenerate well the image edges. So, it is an effective algorithm to detect image edges. References | Related Articles | Metrics

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Restraining bullwhip effect in tight market Li, Yang (1); Gao, Li-Qun (1); Kong, Zhi (1) 2008, 29 (4):  480-483.  DOI: - Abstract ( 316 )   HTML   PDF (242KB) ( 826 )   Discusses the bullwhip effect resulting from the linear assignment mechanism which the suppliers applied to tight market. Then, the bullwhip effect is available to be restrained by way of a reasonable distribution based on the historical record of retailers' goods return rate. In case the supply contract is terminable and the retailers' return rate exceeds the upper limit of supplier's tolerability, the supplier can terminate the supply contracts in goods distribution. And in case the supply contract is interminable, the supplier can choose the function of retailers' order for goods to restrain the high return rate in goods distribution. The two measures are suggested to take because either one can reduce efficiently the bullwhip effect in tight market under different conditions. References | Related Articles | Metrics

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Optimization approach to solving dynamic vehicle routing problems Liu, Shi-Xin (1); Feng, Hai-Lan (1) 2008, 29 (4):  484-487.  DOI: - Abstract ( 381 )   HTML   PDF (665KB) ( 1442 )   A guided local search (GLS) algorithm is presented to solve dynamic vehicle routing problems (DVRP). In the dynamic solving process after an initial solution, the GLS does not exchange customers between vehicles but applies the 2-opt local search operator to updating the servicing sequence for customers, i.e., to solve a traveling salesman problem of traveling routing of each vehicle. A simulation model is thus developed for the dynamic process during which vehicles are in traffic. In the simulation model the GLS algorithm is applied to optimizing the vehicle routes in accordance to the real-time traffic situation, and four rules are applied to judging if the newly optimized vehicle routes are accepted. The simulation results reveal that the GLS algorithm can provide real-time response to dynamic information to satisfy the requirements of solving DVRP. References | Related Articles | Metrics

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Application of principal component analysis to performance evaluation of telecom enterprises Tang, Jia-Fu (1); Li, Run-Sheng (1); Shi, Yong-Gui (1); Fan, Chun-Guang (1) 2008, 29 (4):  488-491.  DOI: - Abstract ( 345 )   HTML   PDF (340KB) ( 1269 )   Combining theoretical study with empirical analysis in research, a KPI (key performance indicators) evaluation model is developed for telecom enterprises. The PCA (principal component analysis) of multivariate statistics is applied to the performance evaluation system with a telecom enterprise taken as multi-objective example to analyze. The evaluation index system based on this model is simple and practical with low operation cost and high accuracy, thus providing a new effective way to evaluate the performance of various telecom enterprises in China. The mathematical evaluation model is composed of 3 principal component indexes as a result of PCA, by which the overall strengths of all departments can be truly reflected and ranked, with the discrepancies between them and the cause both analyzed. The results show that this model is available to evaluate different performances more reasonably and scientifically. References | Related Articles | Metrics

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Simulation research of integrated inventory-transportation problem with different transportation modes Zhang, Jun (1); Tang, Jia-Fu (1); Pan, Zhen-Dong (1) 2008, 29 (4):  492-495.  DOI: - Abstract ( 209 )   HTML   PDF (230KB) ( 578 )   The features and transportation cost structures of three transportation modes for an enterprise combining production with distribution are comparatively analyzed, including independent running, 3rd party logistics and vehicle leasing. Under conditions that the distribution networks is composed of a single supplier, multiple retailers, multiple products and multiple direct delivery, the relationships between the total costs resulting from different optimum solutions to the transportation modes as above are analyzed combining different values of different parameters, especially how the change in parameters affect the total costs when the vehicle leasing was done in an outsourcing way. The result show that the influence of loading charge in an outsourcing way on the total cost is greater than that of any parameters else. References | Related Articles | Metrics

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Control software design and implement of PET based on real-time linux Wang, Yong-Fu (1); Li, Jia-Di (2); Zhao, Hong (3); Liu, Ji-Ren (3) 2008, 29 (4):  496-499.  DOI: - Abstract ( 241 )   HTML   PDF (623KB) ( 822 )   A multi-task framework proposed for PET (positron emission tomography) on the basic principle of real-time system analysis is used to develop PET real-time control system. With the realization of the software part particularly detailed, the system flow chart of the software part is introduced. Then, those mechanic subsystems including scanner bed, rod source, septa and wobble are all verified experimentally that they are available to complete the planned control task and expected motion control precision with stable system operation. Experiment results show the high reliability and real-time response of the proposed PET real-time control system based on multi-task framework. References | Related Articles | Metrics

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Evaluation of communication link in wireless sensor networks Sun, Pei-Gang (1); Zhao, Hai (1); Pu, Ming (2); Zhang, Xi-Yuan (1) 2008, 29 (4):  500-503+520.  DOI: - Abstract ( 235 )   HTML   PDF (449KB) ( 699 )   The existing typical link evaluation measures in wireless sensor networks are investigated, since the evaluation results of RSSI and LQI are inaccurate if they have just been evaluated for directly once. A new evaluation approach is therefore proposed taking the mean RSSI and mean LQI as the measures in link evaluation so as to avoid such as inaccurate evaluation result. Taking the nodes of MicaZ sensors as an experimental platform to investigate the communication links in wireless sensor network, a link evaluation model based on Gauss distribution is proposed and verified with lots of sampled values analyzed statistically. The modeling approach suggested has the generality that the Gauss link evaluation model thus developed will provide reference for not only applications, but also the simulation investigation on upper layer protocols in wireless sensor networks. References | Related Articles | Metrics

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Personalized information retrieval algorithm based on word-correlativity model Tan, Zhen-Hua (1); Cheng, Wei (1); Chang, Gui-Ran (2); Gao, Xiao-Xing (1) 2008, 29 (4):  504-507.  DOI: - Abstract ( 267 )   HTML   PDF (356KB) ( 853 )   An idea is presented about users' personalized information which can be stored by a word-correlativity network, and the way to enable this network to be set up automatically in user's searching process is proposed according to the user's preference. To re-rank the results of queries as response from underlying search engine, three strategies were developed using the word-correlativity to re-evaluate them. Then, a personalized search algorithm using word-correlativity model is presented. A prototype system is thus designed to test the relevant performance of the algorithm. The testing results show that the word-correlativity model can store and form the correlations between key words of a text and verify the correctness of the retrieval algorithm. References | Related Articles | Metrics

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Effects of electric field annealing on recrystallization textures of pure zinc sheets Du, Guang-Yu (1); He, Chang-Shu (1); Zhao, Xiang (1); Zuo, Liang (1) 2008, 29 (4):  508-511.  DOI: - Abstract ( 500 )   HTML   PDF (423KB) ( 543 )   The effects of electric field annealing on the recrystallization textures of commercially pure zinc sheets were studied by means of 3-D ODF (orientation distribution functions) analysis, where the sheets were cold rolled separately with 70%, 80% and 90% reduction and each of them was hold at 160°C for 1, 3, 5, 10, 15 and 30 min. The results showed that the electric field does not change the mechanism of formation and development of their recrystallization textures in annealing process, but increases obviously the recrystallization texture intensities of the sample sheets rolled with 3 different reduction and isothermally annealed, i.e., the electric field can promote the evolution from {1¯018}-plane texture to {1¯013}<101¯1> texture and, among those sample sheets, the 70% cold reduced sheet is the most evident one. References | Related Articles | Metrics

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Effect of cross-shear rolling on the texture of cold-rolling and recrystallized in interstitial free steel He, Tong (1); Liu, Yan-Dong (1); Jiang, Qi-Wu (2); Zuo, Liang (1) 2008, 29 (4):  512-516.  DOI: - Abstract ( 580 )   HTML   PDF (1209KB) ( 669 )   The effect of cross-shear rolling on the cold-rolling and recrystallized texture of IF (interstitial-free) steel was studied, where the rules of simulated shearing strain changing with the ratio of speed of rolls are applied to the texture simulation based on Taylor model to analyze the effect of shearing strain Εxz on texture deformation. The results showed that after cold rolling the componential α fiber texture decreases gradually and γ fiber texture increases slightly with increasing ratio of asynchronous rolling speeds. And the fact is mainly resulting from the additional shearing strain during cross-shear rolling. The formation of {111}<uvw> recrystallization nucleus was found in no relation to the {001}<110> component. Moreover, the volume percentage of recrystallized {111}<112> component resulting from asynchronous rolling is obviously higher than that resulting from synchronous rolling. This is because the volume percentage of {111}<112> component resulting from cold rolling is obviously higher than that resulting from synchronous rolling. References | Related Articles | Metrics

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Temperature field and thermal crown of work rolls on 1700 hot strip mill Guo, Zhong-Feng (1); Xu, Jian-Zhong (1); Li, Chang-Sheng (1); Liu, Xiang-Hua (1) 2008, 29 (4):  517-520.  DOI: - Abstract ( 286 )   HTML   PDF (455KB) ( 1423 )   The FDM (finite difference method) model of temperature field and thermal crown of work roll on 1700 hot strip mill (HSM) was studied. The off-line simulation program was compiled by C++ language and the temperature field and thermal crown were calculated according to the rolling schedule, thus obtaining roll surface temperature and thermal deformation at different moments. The maximum surface temperatures of the work rolls F2, F3 and F4 are about 58.1, 73.1 and 81.2°C and relevant maximum radial deformations are about 193.979, 275.259 and 333.433 μm respectively. The surface temperature distribution and thermal deformation were both affected obviously by roll shift. The computed and measured roll surface temperature were comparatively in good agreement with each other, and the fact showed that the computed roll temperature field and thermal crown model are quite accurate. References | Related Articles | Metrics

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Mechanical property prediction for hot rolled SPA-H steel using Bayesian neural network Jia, Tao (1); Liu, Zhen-Yu (1); Hu, Heng-Fa (2); Wang, Guo-Dong (1) 2008, 29 (4):  521-524.  DOI: - Abstract ( 306 )   HTML   PDF (278KB) ( 772 )   The neural network based on Bayesian method and its application to the mechanical property prediction were studied for hot-rolled SPA-H sheet. Integrated with the Occam's razor theory, a penalty term which could be interpreted as an indication of the complexity of the network was introduced into the objective function to prevent the occurrence of overfitting. Considering the practical problems in the application of the network and based on earlier work which have improved the Bayesian method, the Levenberg-Marquardt algorithm was employed to train the network, thus expediting the convergence rate. The network has been used in the prediction of mechanical properties of hot-rolled SPA-H sheet. Compared with the conventional BP neural network, it has the advantages of faster convergence rate, higher stability and ability for generalization. References | Related Articles | Metrics

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Effect of controlled rolling/cooling on mechanical properties of low-carbon cold heading steel Li, Zhuang (1); Wu, Di (1) 2008, 29 (4):  525-528.  DOI: - Abstract ( 296 )   HTML   PDF (433KB) ( 686 )   Double experiments of controlled rolling/cooling process were carried out on a lab mill and the results showed that the effect of ferrite grain size on the mechanical properties is greater than that of pearlite morphology for the low-carbon cold heading steel. The mechanical properties of the specimens rolled at low temperature are better than rolled conventionally. Best mechanical properties could be obtained by the controlled rolling/cooling process for ferrite grain refining and avoid the formation of Widmastatten structure under conditions that the austenitizing parameters are set very reasonably. In such a way it might be expected to substitute low-carbon for medium-carbon in production of 490 MPa grade cold heading steel without heat-treatment. References | Related Articles | Metrics

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Effect of TSCR parameters on microstructure of Fe-3%Si strip Yu, Yong-Mei (1); Li, Chang-Sheng (1); Xu, Yun-Bo (1); Wang, Guo-Dong (1) 2008, 29 (4):  529-532.  DOI: - Abstract ( 281 )   HTML   PDF (630KB) ( 562 )   TSCR (thin slab casting and rolling) simulation was conducted for the Fe-3% Si strip to investigate the effects of different TSCR parameters on its hot rolling process and normalized microstructure. The results showed that the cross-sectional microstructure is inhomogeneous. When the specimen is rolled after 1200°C for 20 min insulation and under the first two heavier pass reductions and pass reductions decreasing, as a result, the microstructure shows more recrystallized grains which are homogeneously distributed and finer in transition layer with no lengthened band structure found in middle layer. Such a microstructure is advantageous to secondary recrystallization. Compared with the strip by conventional hot rolling process, the average grain size is 1.5 μm bigger, and the dislocation arrangement and the top and middle microstructure look similar. It is important that the microstructure of the hot-rolled strip makes sure of that after normalization. References | Related Articles | Metrics

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Automatic control system based on CORUMTM model and multiple closed loop for tandem cold mill Li, Xu (1); Zhang, Dian-Hua (1); Zhang, Hao (2); Han, Ji-Zheng (2) 2008, 29 (4):  533-536.  DOI: - Abstract ( 282 )   HTML   PDF (965KB) ( 642 )   Introduces briefly process parameters, mechanical parameters and configuration of key sensors of the new 1700 mm 5-stand cold-rolling mill with pickling line in Tangsteel. Investigates mainly the core function of the TCM automation control software package involving the CORUMTM physical process model based on neural network and cost functions and the advanced high accuracy/response and multi-variable closed-loop system to control workpiece gauge, tension and flatness. The practical application results show that the preset based on the advanced process model in combination with online closed-loop control can ensure the strip quality so as to provide the accurate gauge and flatness of finished products. References | Related Articles | Metrics

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Confidence level evaluation for simulation model of continuous cold-rolling force Liu, Xing-Gang (1); Zhang, Guo-Zhi (1); Hao, Li-Na (2); Li, Shan-Qing (3) 2008, 29 (4):  537-540.  DOI: - Abstract ( 289 )   HTML   PDF (181KB) ( 834 )   According to the main theories and technologies of simulation models, the VV&A (verification, validation and accreditation) of cold-rolling force model were simplified considering the characteristics of continuous cold-rolling. An evaluation method of the confidence level of cold-rolling force model is thus presented as follows, which combines inequality coefficient method with sensitivity analysis. The definition of TIC (Theil inequality coefficient) value is given first to justify the cold-rolling force model for simulation, and the TIC value of the model is computed with the data acquired in site to analyze qualitatively the applicability of simulation model. Then, the sensitivity of input parameters to output values is analyzed quantitatively. The validity of the cold-rolling force model is therefore verified by both the qualitative and quantitative ways. The simulation results via exemplification show that they are actually in line with the rolling force model applied to the continuous cold-rolling process. References | Related Articles | Metrics

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Solidification structure of Cu-40%Pb monotectic alloy in high magnetic field Zhang, Lin (1); Wang, En-Gang (1); Zuo, Xiao-Wei (1); He, Ji-Cheng (1) 2008, 29 (4):  541-544+548.  DOI: - Abstract ( 217 )   HTML   PDF (617KB) ( 554 )   The solidification structure of Cu-40%Pb monotectic alloy was experimentally investigated in a 12 T high magnetic field, including the coexistent monotectic morphology of solidification. The results showed that during the solidification in such a magnetic field the rod-like and regularly arranged extra-long Pb-rich phase forms at the centre of specimen. The high magnetic field enables the Pb-rich phase in solidification structure to have a elongating effect, so the percentage elongation is efficient to analyze the result from the elongation effect. The high magnetic field can also hold back the motion of Pb-rich phase droplets and the melt flow along the solidification front, which is just the reason why the extra-long and regularly arranged monotectic structure forms. References | Related Articles | Metrics

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Application of theory and numerical method of steady impressible fluid flow in static electromagnetic field Lei, Hong (1); He, Ji-Cheng (1) 2008, 29 (4):  545-548.  DOI: - Abstract ( 264 )   HTML   PDF (1229KB) ( 616 )   The similarity between fluid mechanism and electromagnetics leads to the similarity between the governing equations of steady fluid flow, electrostatic field and static magnetic field, and there are some similar rules in numerical calculation. All these equations are expressed in terms of convection, diffusion and source, and the numerical method in computational fluid mechanics can be used to calculate the electromagnetic field equations. Based on the analysis of both the mathematic and physical meanings of upwind (or downwind) scheme and forward (or backward) difference scheme, it is suggested that the upwind and downwind schemes are available to solve the equations involving electric charge movement, and the upwind scheme available to solve the equations for fluid flow. References | Related Articles | Metrics

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Thermodynamic model to calculate nitrogen solubility in Fe-Cr-Mn alloys Li, Hua-Bing (1); Jiang, Zhou-Hua (1); Zhang, Zu-Rui (1); Xu, Bao-Yu (1) 2008, 29 (4):  549-552.  DOI: - Abstract ( 257 )   HTML   PDF (1187KB) ( 743 )   A thermodynamic model to calculate nitrogen solubility in different phases of Fe-Cr-Mn alloy system was developed on the basis of earlier works and regular melt model. The calculation results of 18Cr-18Mn alloy showed that the nitrogen solubility in different phases increases with increasing nitrogen partial pressure, and the δ ferrite zone becomes smaller even disappears. So increasing nitrogen partial pressure can prevent the porosity forming during solidification. Increasing properly the contents of component elements of austenite in the melts, the δ ferrite zone where the nitrogen solubility is low becomes smaller even disappears during the solidification of the melt, thus decreasing the potential nitrogen precipitates during solidification. The calculation results are in good agreement with what were done in earlier works. References | Related Articles | Metrics

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Experimental study on drying characteristics for sewage sludge during oil production Du, Tao (1); Cai, Jiu-Ju (1); Dong, Hui (1); Yang, Bing (1) 2008, 29 (4):  553-556.  DOI: - Abstract ( 275 )   HTML   PDF (384KB) ( 635 )   Based on the analyses of physical and chemical features of oily sludge, the influencing factors on the drying characteristics of sewage sludge in Liaohe Oil Field were studied and some conclusions were drawn as follows. The mixture ratio of coal, sludge particle size and drying air temperature and flowrate are the main influencing factors on the drying characteristics of the oily sludge, among which the last two affect to a certain extent. The greater the mixture ratio of coal, the smaller the sludge particle size; and the higher the temperature the drying air, the higher the flowrate of drying air and the drying rate. Moreover, the sludge drying effect will be obviously better if the mixture ratio of coal is about 20%, the sludge particle size approximately 20 mm and the suitable temperature of drying air near 125°C. References | Related Articles | Metrics

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Application of bayesian network to reliability assessment of mechanical systems Yin, Xiao-Wei (1); Qian, Wen-Xue (1); Xie, Li-Yang (1) 2008, 29 (4):  557-560.  DOI: - Abstract ( 351 )   HTML   PDF (313KB) ( 1912 )   A new method based on Bayesian network was proposed to assess the mechanical system reliability because of the limitation of fault tree used in reliability assessment. A fault tree was built first according to the block diagram of system reliability, then it was mapped onto a Bayesian network to generate a conditional probability distribution table so as to assess the system reliability by inference of Bayesian network. The method is able not only to compute the reliability indices of mechanical system but also to analyze easily the effects of a certain components on the system reliability to recognize the vulnerable positions of the system. The validity of the method proposed is verified by exemplification. References | Related Articles | Metrics

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Flexible job shop scheduling for decreasing production costs Liu, Xiao-Xia (1); Xie, Li-Yang (1); Tao, Ze (2); Hao, Chang-Zhong (2) 2008, 29 (4):  561-564.  DOI: - Abstract ( 259 )   HTML   PDF (214KB) ( 611 )   Considering the inventory cost of workpieces in process, machining time cost, direct labor cost, inventory cost of early finished products and cost increment due to late finished products, a method calculating production cost of dual-resource(machine tool plus labor) flexible job shop scheduling is proposed. A new hybrid genetic algorithm is designed by embedding simulated annealing algorithm (SA) into genetic algorithm (GA), where GA is used to search for a group of better solutions to the problem of minimizing production cost and then SA is applied to searching them for the best one. Introducing an operation-based encoding and a new decoding method, several kinds of crossover operations are used to enable the algorithm to search the optimal solution in solvable space as far as possible. To avoid missing the optimal solution during the course of evolution, the optimized solution in every generation is kept then updated uninterruptedly. An example is given to prove that the scheduling method is feasible and efficient. References | Related Articles | Metrics

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Job shop scheduling and its optimization based on particle swarm optimizer He, Li (1); Liu, Yong-Xian (1); Xie, Hua-Long (1); Liu, Xiao-Tian (1) 2008, 29 (4):  565-568.  DOI: - Abstract ( 531 )   HTML   PDF (872KB) ( 1276 )   Considering the conventional algorithms' low efficiency of search especially global search, PSO-based solution to job shop scheduling problem is presented. According to the characteristics of the problem, the PSO coding and optimization are studied to determine the way of coding and operation, which is more adaptable to job shop scheduling. The job shop scheduling part of the system is then programmed with the algorithm. Simulation results showed that setting the suitable parameters can provide an excellent working sequence to adapt to the dynamic job-shop problem. References | Related Articles | Metrics

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Temperature control system of gene-type gain amplifier Wang, Dan (1); Li, Xin (1); Wang, Xiao-Guang (1); Li, Ming (1) 2008, 29 (4):  569-572.  DOI: - Abstract ( 229 )   HTML   PDF (379KB) ( 652 )   Based on the theory of fuzzy PID control, a high flexible intelligent controller is designed in combination with practical application. The controller uses a chip microprocessor to control temperature detection circuit. According to the real-time performance of the temperature control cabinet, the system adjusts the PID parameter online to improve its exactitude and make the control more sound and reasonable. The Matlab/Simulink system simulation software is used to simulate the common PID and fuzzy PID with the results comparatively discussed. It is thus revealed that the fuzzy PID controller designed has higher stead-state precision and faster response speed, as well as better overshoot. The serial communication is given between the chip microprocessor and upper monitor to strengthen the intellectuality and interaction of the detection system so as to meet designed request. The detection circuit and the serial communication program both have high universality and transplantability. References | Related Articles | Metrics

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Preparation of ultrafine calcium sulfate whiskers by hydrothermal synthesis Yuan, Zhi-Tao (1); Wang, Xiao-Li (1); Han, Yue-Xin (1); Yin, Wan-Zhong (1) 2008, 29 (4):  573-576.  DOI: - Abstract ( 239 )   HTML   PDF (664KB) ( 1691 )   Hydrothermal synthesis was applied to the preparation of ultrafine calcium sulfate whiskers in airtight reactor with gypsum as primary material. The optimum conditions for the preparation were that the reaction temperature is 120°C and initial pH value of CaSO4·2H2O slurry is 9.8-10.1 with mass fraction 5% and mean particle size 18.1 μm, as a result of SEM to analyze the diameter of CaSO4 whiskers. Then, the ultrafine CaSO4 whiskers with average diameter 0.19 μm and aspect ratio 98 were obtained. The conclusion drawn from the preparation will play a guiding role in the industrial production of ultrafine calcium sulfate whiskers. References | Related Articles | Metrics

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Calculation and analysis of diversity of domestic primary energy supply Li, Lian-De (1); Wang, Qing (1); Liu, Hao (1); Song, Yang (1) 2008, 29 (4):  577-580.  DOI: - Abstract ( 250 )   HTML   PDF (144KB) ( 909 )   The change in the diversity of China's primary energy supply was calculated and analyzed using the Shannon-Weiner index. The results showed that, from 1949 to 2005, the primary energy supply tended towards varied resources from the initial single one. In 1951, there were only 3 kinds of supplying resources and the minimum Shannon-Weiner index was 0.1545 with the minimum evenness 0.096, where the coal came up to 97% of the total supply and the rest including petroleum and hydropower was so poor that was just about 3%. In that period China's primary energy supply was at the lowest level. In 2001, the diversity of energy supplies came up to its peak, i.e., the maximum Shannon-Weiner index was 0.8669 with the maximum evenness 0.5387, including 5 kinds of supplying resources available. The differences between the percentages of those primary energy supplies became lowest in that year. References | Related Articles | Metrics

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On the separation performance of superfines dust by mini-cyclones Hao, Wen-Ge (1); Wang, Shang-Yuan (1); Ding, Shu (1); Wu, Yan (1) 2008, 29 (4):  581-584.  DOI: - Abstract ( 202 )   HTML   PDF (230KB) ( 850 )   Mini-cyclones are used to separate superfines about 1 μm from industrial dust for dust classification. A 2-D mathematical model is thus developed, by which the dust classification efficiency is analyzed and proved just in relation to Stokes number. Experimental investigation was conducted for 3 types of mini-cyclones at different air flowrates through their inlets. The result showed that a linear relationship is found between the classification efficiency and Stokes number in the Rosin-Rammler coordinates. A new theoretical expression is derived here, by which the calculated value of classification efficiency is closer to the measured value in comparison with other theoretical expressions. So, it is comparatively an accurate calculation method of separation efficiency. When the air flowrate is in the range from 15 to 25 m/s at the inlets of 3 types of mini-cyclones in experiment, the sizing size of superfines for classification can come down to 0.6 μm. References | Related Articles | Metrics

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Deformation calculation of steel-concrete composite girders with prestressed FRP sheets under symmetrical point load Wang, De-Xuan (1); Wang, Lian-Guang (1); Zhang, Xin-Ying (2); Liu, Yan-Yan (2) 2008, 29 (4):  585-588.  DOI: - Abstract ( 319 )   HTML   PDF (309KB) ( 701 )   The interface slip will occur unavoidably in the steel-concrete composite girder with prestressed FRP sheets if the girder is under the external load, and the internal force of prestressed FRP sheets will gradually increase with the external load to redistribute the internal force of the girder so as to affect the bearing capacity and deformation of the girder. The differential equations of deformation are therefore derived on the basis of the theory of elasticity, considering the effect of the relative interface slip internal force increment of FRP sheets. And the calculation formulas of deformation are given for the composite girder under symmetrical point load. The calculated results show that the deformation of composite girder increases gradually with the interface slip, but the effect of internal force increment of the prestressed FRP sheets on the composite girder deformation is so small that can be ignored, thus giving the reduced calculation formulas of deformation for the steel-concrete composite girder with prestressed FRP sheets. References | Related Articles | Metrics

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Corrosion damage calculation for steel tube in rectangular steel-reinforced concrete Ha, Na (1); Wang, Lian-Guang (1) 2008, 29 (4):  589-592.  DOI: - Abstract ( 314 )   HTML   PDF (964KB) ( 503 )   Expansive force will occur around the reinforced steel in concrete due to corrosion, and it increases with corrosion damage and, as a result, it will crack the concrete cover so as to shorten the durability of steel-reinforced concrete structures. Based on the elastic mechanics, a corrosion damage calculation model is therefore developed for the steel tube in rectangular steel-reinforced concrete pipes when concrete is cracking due to corrosive expansion, with a relevant formula given. In addition, the influencing factors on the corrosion damage are analyzed, and the results indicate that the corrosion damage increases with the thickness of concrete cover, inner diameter of steel tube and concrete strength grade, but it decreases with increasing outer diameter of steel tube and expansion rate due to corrosion. References | Related Articles | Metrics

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Inventory model of deteriorating items with stock-out partial backlogging Zhong, Lei-Gang (1); Wei, Ming (1); Li, Ya-Feng (1) 2008, 29 (4):  593-596.  DOI: - Abstract ( 249 )   HTML   PDF (272KB) ( 790 )   An inventory model is developed for deteriorating items during stock-out which is partial backlogging. In the earlier researches on inventory of deteriorating items, the unsatisfied demand was usually assumed that it is completely due to backlog, and the purchase cost and the cost of lost sales were ignored in calculating the total cost, thus resulting in a big gap between the inventory model and reality. The backlogging rate of unsatisfied demand linearly depending on the total number of customers in the waiting line is used to present the condition during stock-out and both the purchase cost and the cost of lost sales are included in the total cost, then an optimal inventory model is developed by extending the constant demand function of goods into time-varying concave demand function. A simple algorithm is also provided to find the optimal ordering policy for this model. Further, a numerical example is given to illustrate the results. References | Related Articles | Metrics

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Empirical analysis of high-tech company's performance and governance structure in China Liu, Ye (1); Li, Kai (1); Qin, Li-Na (1) 2008, 29 (4):  597-600+604.  DOI: - Abstract ( 218 )   HTML   PDF (1054KB) ( 709 )   The correlation between corporate governance and the values as the explained variables of performance of 40 listed high-tech companies as samples on the Shanghai and Shenzhen stock markets from 2002 to 2004 was analyzed. The results show that the distinct negative correlation is between Tobin's Q ratio and company's size, while the positive correlation is between ROE and company's size. The empirical test results for the present situation of China's listed high-tech companies were analyzed. The results reveal that the reason why the high-tech companies differ from the other conventional companies in which the ownership is separated from the control of business operations is that in high-tech companies the human capital and the intangible assets under its control make more important contribution to their values than tangible assets. References | Related Articles | Metrics

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Application of GARCH-EVT model in dynamic VaR Gao, Ying (1); Zhou, Xin (1); Jin, Xiu (1) 2008, 29 (4):  601-604.  DOI: - Abstract ( 386 )   HTML   PDF (232KB) ( 711 )   Considering both the characteristics of clustering volatility and fat-tail of the data distribution of returns on financial assets especially the impact of conditional heteroscedaticity on the estimate of dynamic VAR, a GARCH-EVT model is developed by EVT (extreme value theory) to calculate the dynamic VAR(value at risk) of SSCI (Shanghai stock comprehensive index), then the model is compared with the GARCH-NORMAL model. The empirical analysis and posterior test results reveal that the GARCH-EVT model is superior to the GARCH-NORMAL model, because the former can solve better the problems of clustering volatility and fat-tail phenomenon. So it provides the managers and investors with quantitatively useful means for risk control. References | Related Articles | Metrics

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Labeling HeLa Cells with CdTe quantum dots Chen, Qi-Fan (1); Yang, Dong-Zhi (1); Wang, Wen-Xing (1); Xu, Shu-Kun (1) 2008, 29 (4):  605-608.  DOI: - Abstract ( 189 )   HTML   PDF (428KB) ( 656 )   Mercaptopropionic acid was taken as stabilizer to synthesize water-soluble CdTe quantum dots, and the dots were covalently linked to the anti-CEA8 (carcinoembryonic antigen) antibody for rabbit and anti-rabbit immunoglobulin for goat by the carboxyl functional groups covered by outer layer of CdTe QDs. The conjugation has obvious effect on the optical properties of CdTe QDs, and the conjugation enhances fluorescence intensity in the presence of anti-CEA8 for rabbit and anti-rabbit immunoglobulin for goat with the blue-shift of their maximum emission peaks, which are proved more stable than that of bare CdTe QDs. Both the QDs-antibody and QDs-immunoglobulin are used as bio-labels to directly and indirectly label live or fixed HeLa cells. Through fluorescence microscopy, it is observed that HeLa cells can be labeled through both direct and indirect methods, but the latter has better specificity. All these results demonstrate that cancer cells can be successfully stained through immunoreactions between antigen and antibody. References | Related Articles | Metrics