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15 April 2012, Volume 33 Issue 4 Previous Issue    Next Issue
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Centrifugal compressor modeling based on differential evolution algorithm Niu, Da-Peng (1); Wang, Xiao-Gang (1); Dong, Shi-Jian (1); Wang, Fu-Li (1) 2012, 33 (4):  457-460.  DOI: - Abstract ( 494 )   HTML   PDF (313KB) ( 712 )   The mechanism model of single stage compressor was built on the basis of the centrifugal compressor's characteristics, the fluid mechanics, the energy conservation and the mass conservation principles. Several models of single stage compressors in series were integrated to compose the mechanism model of a steel CCPP gas system's three-level centrifugal compressor on the low pressure side. The parameter identification problem of the multi-stage compressor model was transformed into an optimization problem, and differential evolution algorithm was used to decide the unknown parameters in the model. Model validation results showed that the developed model could reflect the operating characteristics of centrifugal compressors and laid a model foundation for compressors' anti-surge control. References | Related Articles | Metrics

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Stability analysis based on state observer for singular networked system Xing, Wei (1); Li, Ning (1) 2012, 33 (4):  461-464.  DOI: - Abstract ( 565 )   HTML   PDF (257KB) ( 434 )   Assuming that the transfer delay is shorter than the sampling period and the successful rate of data packet transfer is given, the singular networked control system could be modeled as an asynchronous dynamical system for a class of the regular, impulsive-free and impulsive observable singular networked control systems with delay and data packet dropout. The stability conditions of the system were given with the Lyapunov function and LMI method, and the feedback controller with the normal state observer was obtained. Simulation results indicated the effectiveness of the proposed method. References | Related Articles | Metrics

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Improved unfalsified control algorithm based on gradient method Zheng, Yan (1); Jia, Zhi-Wen (1); Deng, Jia-Jia (1) 2012, 33 (4):  465-468.  DOI: - Abstract ( 489 )   HTML   PDF (278KB) ( 502 )   An improved unfalsified control algorithm based on gradient method was proposed to overcome the defects that the unfalsified control algorithm is easy to fall into the poles and has slower convergence speed. The momentum term, which is a parameter variation of the moment before, was added into the adaptation rule to make the parameter jump out of the local extreme poles and improve the system convergence speed effectively. The algorithm just makes use of the collected data, but not depends on the system model. The simulation results verified the validity of the improved unfalsified control algorithm based on gradient method. References | Related Articles | Metrics

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Pavement crack detection based on direction feature and gravitational model Wu, Cheng-Dong (1); Lu, Bai-Hua (1); Chen, Dong-Yue (1); Wang, Li (1) 2012, 33 (4):  469-472.  DOI: - Abstract ( 448 )   HTML   PDF (635KB) ( 681 )   A pavement crack detection algorithm was proposed on the basis of directional features and gravitational model to overcome the shortcomings of the existing global methods. According to the extension and local transition of cracks, the endpoints of cracks were firstly searched. The direction factors and directional derivative discrimination criterion were designed, which reflect the linear features of cracks. Crack discrimination was localized in the possible neighborhood to prevent effectively the introduction of redundant information. Based on the human vision characteristics and physics theory, a crack gravitational model was designed to improve the robustness of crack connection under the noise environment. By combining color distance, a multiple criteria discriminant function of crack extension and connection was designed to detect crack pixel area. The experimental results indicated the validity of the proposed method. References | Related Articles | Metrics

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Design of sliding mode controller for MIMO system and its application Yu, Chi (1); Gong, Ming-Long (1) 2012, 33 (4):  473-475+481.  DOI: - Abstract ( 1022 )   HTML   PDF (465KB) ( 1742 )   The problem of sliding mode control was investigated for a class of MIMO system. A modified exponential approximation law was used to effectively reduce the chattering caused by variable structure control, and the theoretical proof was given. The proposed method was applied to the design of hydraulic looper systems, where the coupling between looper height and tension control were regarded as interference. Simulation results demonstrated the effectiveness of the proposed method. The controller could make the looper systems get better control performance and reach a stable equilibrium state quickly. References | Related Articles | Metrics

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Solving repetition of Asian-rule in Chinese chess Wang, Jiao (1); Sun, Ying-Long (1); Lü, Hui-Zhan (1); Yang, Hui (1) 2012, 33 (4):  476-481.  DOI: - Abstract ( 702 )   HTML   PDF (400KB) ( 1040 )   The repetition judgment is a big challenge due to the unique restrictions in Chinese Chess. To solve the problem, an ideal model was proposed. For solving the repetition direction, the Asian-rule was classified and incorporated to greatly simplify the rule. The proposed model detects firstly repetition according to Asian-rule, and then judges the detected repetition to obtain which side in the repetition will win. The experimental results indicated the validity and practicability of the presented model. References | Related Articles | Metrics

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Improved conversion algorithm from NFA to DFA Jing, Mao-Hua (1); Li, Guo-Rui (1); Shi, Wen-Bo (1); Cai, Shu-Xun (1) 2012, 33 (4):  482-485.  DOI: - Abstract ( 787 )   HTML   PDF (769KB) ( 929 )   The mechanism and complexity of the conversion algorithm from nondeterministic finite automata (NFA) to deterministic finite automata (DFA) were studied, and a great number of repeated traversal and invalid traversal phenomenon in the well known SUBSET algorithm were especially studied. An improved MF-SUBSET algorithm was proposed to solve the above problem. The simulation results indicated that the present searching strategy could be decided by the proposed MF-SUBSET algorithm through increasing status flags and traversal path flags, which could obviously avoid the repeated traversal and invalid traversal operation and effectively improve the conversion efficiency. References | Related Articles | Metrics

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FPGA based MPSoC for multimedia processing Li, Jing-Jiao (1); Lu, Zhen-Lin (1); Wang, Ai-Xia (1); Wang, Jiao (1) 2012, 33 (4):  486-490.  DOI: - Abstract ( 498 )   HTML   PDF (1796KB) ( 547 )   A two-cores embedded processor (TEP) model was proposed to overcome the problems of slow processing speed and the limited main frequency ascension of the embedded mononuclear processor. On the basis of the nonuniform storage structure, the simulated distributed storage structure was presented to solve reliance and distribution of memory when the processor is running. The arbitration mechanism of the subordinate unit was proposed to realize the access of sharing resources for the accessing memory problem of the share data storage among multiple processors. On the basis of the separation of the message data, a kind of data transmission scheme was proposed to overcome a large number of the data transmission and the higher communication spending of the multiple processors facing the multimedia applications. The system was realized and verified on the FPGA platform, which indicated that TEP got a good performance on accelerator with less resource/transmission spending. References | Related Articles | Metrics

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Service environment model for continuous optimization execution of software services Na, Jun (1); Zhang, Bin (2); Zhang, Li (1); Zhu, Zhi-Liang (1) 2012, 33 (4):  491-494+499.  DOI: - Abstract ( 534 )   HTML   PDF (273KB) ( 513 )   From the point of view for environment modeling, a service environment model was proposed to meet the continuous optimization execution of software services in their life cycle. On the basis of Pareto dominance, services were selected by their multiple quality criteria from bottom to top to form a minimal exhaustive service set (optimal service environment) for all executing instances. The continuous support of optimization execution of software services was realized by dynamically updating the optimal service environment with service changing. The definition of service environment model was given, and so were the methods for initially constructing and dynamically updating the optimal service environment. Experimental results indicated the validity of the proposed service environment model. References | Related Articles | Metrics

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Property-based efficient attestation scheme in standard model Yue, Xiao-Han (1); Gong, Shu-Li (2); Zhou, Fu-Cai (1); Ren, Yi (1) 2012, 33 (4):  495-499.  DOI: - Abstract ( 426 )   HTML   PDF (188KB) ( 754 )   A new property-based attestation (PBA) scheme was proposed to solve the problem of platform configure information disclosure caused by the traditional platform attestation in the trusted computing environment. The security model of the scheme was established, and the construction of the scheme was given, including setup, issue, attestation, verification and revocation algorithms. Compared with the existing PBA scheme, the proposed scheme is more effective, that is, the transmission spending is smaller and the computation efficiency is higher. The scheme was attested in the standard model, and the results indicated its correctness, unforgetability and anonymity. References | Related Articles | Metrics

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Improved KPCA fault identification method based on data reconstruction Wang, Shu (1); Feng, Shu-Min (3); Chang, Yu-Qing (1); Wang, Fu-Li (1) 2012, 33 (4):  500-503.  DOI: - Abstract ( 572 )   HTML   PDF (481KB) ( 1173 )   Compared with the principal component analysis (PCA) method, kernel principal component analysis (KPCA) method has more advantages in the monitoring of nonlinear processes. However, it is difficult to find an inverse mapping function from the feature space to the original space for KPCA, resulting in great difficulties for the KPCA-based fault diagnosis. To solve this problem, the fault identification index was improved on the basis of KPCA fault data reconstruction method. The improved method could identify both univariate faults and multivariate faults. In addition, the proposed method could also reduce calculation and avoid the defect that the traditional fault detection methods could only identify univariate faults. The simulation results indicated the feasibility and effectiveness of the proposed method by testing it in the Tennessee-Eastman process. References | Related Articles | Metrics

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Dynamic recrystallization and deformation resistance of EH36 ship plate steel Yang, Hao (1); Zhou, Xiao-Guang (1); Liu, Zhen-Yu (1); Wang, Guo-Dong (1) 2012, 33 (4):  504-508.  DOI: - Abstract ( 555 )   HTML   PDF (2324KB) ( 747 )   The stress-strain curves of EH36 ship plate steel were gained with MMS-200 thermo-mechanical simulator in the single-pass compress deformation test. The influence of deformation temperature, deformation rate and strain on recrystallization behavior was studied. The dynamic recrystallization model and the deformation resistance model were established for the steel. The results showed that the higher deformation temperature, the lower strain rate and the bigger strain are advantageous for dynamic recrystallization. The computed activation energies of dynamic recrystallization and deformation resistance are in good agreement with the measured data, showing the validity of the proposed models. References | Related Articles | Metrics

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Control method of cooling rate in advanced cooling system for plate mill Wang, Bing-Xing (1); Hu, Xiao (1); Wang, Zhao-Dong (1); Wang, Guo-Dong (1) 2012, 33 (4):  509-512.  DOI: - Abstract ( 608 )   HTML   PDF (1029KB) ( 789 )   The influencing factors and the control method of plate cooling rate during a controlled cooling process after rolling were researched for the 4300 mm plate mill with the advanced cooling system. The effect of heat transfer, nozzle and the flow rate of header on cooling rate was analyzed to confirm the control scope of the cooling rate for different thickness plates. The calculation model of cooling rate was established to improve the control accuracy of cooling rate by combining the self-learn method. The control results showed that the cooling rate of the steel 12MnNiVR was controlled with high accuracy. References | Related Articles | Metrics

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Effect of initial microstructure on final microstructure and mechanical properties of V-microalloyed trip-aided sheet steel Xu, Yun-Bo (1); Hou, Xiao-Ying (1); Wang, Ye-Qin (2); Wu, Di (1) 2012, 33 (4):  513-516+520.  DOI: - Abstract ( 494 )   HTML   PDF (1759KB) ( 707 )   The effect of initial microstructure on the final microstructural characteristics and the mechanical properties was investigated for low silicon TRIP steel containing phosphorus and vanadium after hot rolling, cold rolling and continuous annealing. The two different microstructures were obtained by different hot rolling processes, i. e., F+P steel and F+B steel. Compared with F+P steel, the volume fractions of bainite and retained austenite in F+B steel are higher for the same cold rolling and continuous annealing process; the retained austenite is smaller in size and more dispersive in distribution, and the yield strength and the tensile strength are higher, but the elongation, the n value and the r value are slightly lower. The tensile strength reaches up to 980 MPa, and the strength-ductility balance is 21952 MPa·% for F+B steel. References | Related Articles | Metrics

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Effect of stress concentration on high cycle fatigue life of 2024 Al alloy Liu, Chang-Sheng (1); Li, Hai-Xiong (1); Yang, Mi-Jun (1); Chen, Sui-Yuan (1) 2012, 33 (4):  517-520.  DOI: - Abstract ( 747 )   HTML   PDF (1540KB) ( 1581 )   The high cycle fatigue life of 2024 Al alloy was studied at room temperature, and the S-N curves of 2024 Al alloy were obtained under different stress states. The fracture morphology, the crack initiation/propagation mechanism, as well as the relationship between structure and fatigue performance of fatigue specimens were analyzed. The results showed that the fatigue limit decreases with increasing stress concentration coefficient, and the fatigue limit decreases with the stress ratio under the same stress concentration coefficient. The fatigue fracture of 2024 Al alloy is mainly transgranular fracture. The second phases play the role of restraining the propagation of fatigue crack, and improving obviously the high cycle fatigue strength of 2024 Al alloy. References | Related Articles | Metrics

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Limit load of thin-walled cylinder and spherical shell with GM yield criterion Zhao, De-Wen (1); Zhang, Lei (1); Zhang, Shun-Hu (1); Li, Xiu-Ling (1) 2012, 33 (4):  521-523+532.  DOI: - Abstract ( 765 )   HTML   PDF (628KB) ( 961 )   The GM yield criterion was first applied to analyzing the limit loads of thin-walled cylinder and spherical shell subjected to internal pressure, and the analytical solutions were obtained. The limit loads for both cylinder and spherical shell are the functions of the thickness, diameter as well as the yield strength of the material. The limit loads increase with the increasing of the yield strength and the thickness, and the decreasing of the diameter. Compared with Mises, Tresca and TSS criteria, the solution of GM criterion lies just between the TSS and Tresca solutions, and it is close to Mises solution and just corresponds to the midline of the error triangle. The limit load based on GM criterion increases linearly with the ratio of thinness to diameter. References | Related Articles | Metrics

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Limit load of simply supported circular plate under linearly and uniformly distributed load Zhang, Shun-Hu (1); Zhao, De-Wen (1); Song, Hong-Yu (1); Gao, Cai-Ru (1) 2012, 33 (4):  524-527.  DOI: - Abstract ( 800 )   HTML   PDF (329KB) ( 598 )   The limit loads of simply supported circular plate under linearly and uniformly distributed load were analyzed with weighted residual method and Mises yield criterion. Three different trial functions were selected to obtain the analytical solutions of limit loads. The obtained solution is the function of circular plate radius and ultimate bending moment, and it decreases with increasing circular plate radius. The results showed that Tresca criterion forecasts the lower limit of limit load, while TSS criterion forecasts the upper limit of limit load. The limit load forecasted by the weighted residual method just lies between the TSS and Tresca solutions. References | Related Articles | Metrics

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Tension control technique for hydraulic-tension reversible experimental cold mill Sun, Tao (1); Wang, Gui-Qiao (1); Wu, Yan (1); Zhang, Hong (1) 2012, 33 (4):  528-532.  DOI: - Abstract ( 578 )   HTML   PDF (780KB) ( 895 )   Only a tension feedback closed loop controller cannot meet the requirements of the speed synchronizing between hydraulic-tension cylinder and workpiece and keeping the stable tension at the same time for hydraulic-tension reversible experimental cold mill. To solve the problem, a new combined control technique was proposed by combining a speed feedforward controller with a tension feedback controller. The feedforward controller computes the setting flux according to the setting rolling speed, and then computes the opening scale of servo valve. The feedback controller uses a PI controller to compute the opening scale of servo valve. The outputs of feedforward and feedback controller were summed as the total opening scale of servo valve. The proposed technique was applied successfully in a 450 mm hydraulic-tension experimental cold mill. References | Related Articles | Metrics

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Arc line method of singular point and its application Mei, Rui-Bin (1); Li, Chang-Sheng (2); Liu, Xiang-Hua (2) 2012, 33 (4):  533-536.  DOI: - Abstract ( 575 )   HTML   PDF (554KB) ( 665 )   The smooth transition of the arc line on the corner of entry of roll gap was used to deal with the first class of singular point during the simulation of common rolling, and a 2D RPFEM (rigid-plastic FEM) program was developed. The velocity field, the rolling force, the iteration steps and the convergence were computed and analyzed according to the actual rolling data. The results showed that the measured rolling force is in good agreement with the calculated value by arc line/traditional method, and the error is less than 10%. The arc line method can reflect the velocity change about singular point and restrain singularity. Compared with the traditional method, the average iteration steps reduce about 26% and the stability improves about 55%. The arc line method is in favor of reducing computation time and improving stability on line. References | Related Articles | Metrics

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Melting separation of ore-coal composite pellet at low temperature Zhu, Bing-Xiu (1); Wei, Guo (1); Jiang, Xin (1); Shen, Feng-Man (1) 2012, 33 (4):  537-541.  DOI: - Abstract ( 524 )   HTML   PDF (1027KB) ( 758 )   The melting separation of metal and slag was investigated by direct reduction of ore-coal composite pellet at low nC/nO followed by melting separation at low temperature. The results showed that a small quantity of slag (2FeO·SiO2) exists in iron nugget at 1300°C, nC/nO=0.8 and 55 min of reduction-melting time. When the reduction-melting time is 60 min, the metal and slag are completely separated, and almost no slag exists in iron nugget. For the ore-coal composite pellet of nC/nO=0.8 or 0.85, the mass fraction of FeO in slag is relatively higher, the melting point is lower and the slag is easy to be separated from metal after reduction. For the ore-coal composite pellet of nC/nO=0.9, the mass fraction of FeO in slag is lower and the melting point is higher, and the slag is not easy to be separated unless heating at higher temperature or for longer melting time. When nC/nO=0.8, and reduction-melting time is 60 min at 1320°C, the recovery rate of iron is greater than 86.1%, and the mass fraction of iron in iron nugget is about 94.8%. References | Related Articles | Metrics

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Burden charging process for shaft furnace of COREX 3000 Li, Qiang (1); Liu, Dong-Liang (1); Zhang, Li-Juan (1); Zou, Zong-Shu (1) 2012, 33 (4):  542-545.  DOI: - Abstract ( 619 )   HTML   PDF (1013KB) ( 864 )   The burden charging process was experimentally studied for the gimbal distributor of pre-reduction shaft furnace of COREX 3000. The similarity criteria were derived by dimension-harmony principle, and a 1:5 scale cold model was constructed. The effect of distributor parameters on the behavior of burden charging was studied. The results showed that the chute inclination angle of the gimbal distributor has significant effect on the radial bulk density distribution. The position of minimum bulk density moves to the shaft wall with increasing the chute inclination angle. The peak value of bulk density decreases and its position moves to the shaft wall with the elevation of stock line. The chute rotation speed has little effect on the bulk density. References | Related Articles | Metrics

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Determination of cohesive zone boundary in COREX melter gasifier by image processing method Han, Li-Hao (1); Luo, Zhi-Guo (1); Zou, Zong-Shu (1); Zhang, Yu-Zhu (2) 2012, 33 (4):  546-550.  DOI: - Abstract ( 466 )   HTML   PDF (1047KB) ( 715 )   A two-dimensional physical model of COREX melter gasifier was constructed to study experimentally the melting behavior of burden in the furnace. Paraffin was used to simulate DRI, and corn was used to simulate coke and lump coal. High-speed camera was used to record the experimental images. An image processing method was developed to characterize the cohesive zone boundary according to the color change of burden before and after the experiment. The proposed method can give the cohesive zone boundary, and thus the position and thickness can be obtained. The variation of the cohesive zone under various experimental conditions was examined. The effect of operation condition on the cohesive zone can thus be analyzed by the proposed method in the future studies. References | Related Articles | Metrics

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Curing kinetics of allyl phenolic resin Liu, Yang (1); Liu, Shi-Wei (1); Li, Zhi-Qiang (1); Yu, Jing-Kun (1) 2012, 33 (4):  551-554.  DOI: - Abstract ( 725 )   HTML   PDF (1004KB) ( 864 )   The curing behavior of allyl phenolic resin was analyzed at different heating rates using differential scanning calorimetry. The obtained kinetic data were treated by Kissinger and KAS(Kissinger-Akahira-Sunose) methods to obtain the curing reaction kinetic parameters. A curing kinetics model was established for allyl phenolic resin. Compared with phenolic resin, the curing temperature of allyl phenolic resin is higher, the reaction order is closer to 1, and the average activation energy of the curing reaction is lower, 111.45 kJ/mol. The activation energy of allyl phenolic resin is almost constant and changes little with temperature in the curing process. The curing kinetics model of allyl phenolic resin provides a theoretical basis for the study of curing process parameters. References | Related Articles | Metrics

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Metallurgical properties of refining slag with different basicities Deng, Zhi-Yin (1); Zhu, Miao-Yong (1); Zhong, Bao-Jun (2); Dai, Yong-Gang (2) 2012, 33 (4):  555-558.  DOI: - Abstract ( 674 )   HTML   PDF (1028KB) ( 737 )   Based on industrial tests, the deoxidation and desulfurization capabilities and inclusion control performance of 4 refining slags were studied with gas analysis, composition analysis and SEM examination. The results showed that the effect of slag basicity on deoxidation capability is greater than that of Al2O3 mass fraction. The higher the basicity is, the greater the deoxidation capability of the slag is. The deoxidation capability reaches almost the maximum when the basicity is about 4 (slag 3). For desulphurization, the higher the basicity is, the greater the desulphurization capability of the slag is. The desulphurization capability will be lost when the slag basicity decreases to about 1. 5. The increase of desulphurization capability with basicity of slag becomes slower at basicity above 3. 5. Compared with slag 4, slag 3 can control the calcium aluminate inclusions to certain extent, and it can thus be selected as refining slag for 35CrMo. References | Related Articles | Metrics

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Effect of stirring on flow characteristic of box-type mixing/clarifying tank Zhao, Qiu-Yue (1); Zhang, Ting-An (1); Liu, Yan (1); Wang, Shu-Chan (1) 2012, 33 (4):  559-562.  DOI: - Abstract ( 669 )   HTML   PDF (1454KB) ( 889 )   An improved box mixing/clarifying tank was proposed to solve the problem of mixing/clarifying tank. The flow characteristic was simulated and studied by ANSYS/FLUENT in the improved new type mixing/clarifying tank. When the speeds of oil and water are 0.22 and 0.11 m/s, respectively, the rotation speeds of mixing room and clarifying room are 800 and 20 r/min, respectively, compared with the traditional extraction tank, the mixed zone is thinner near the blades in the new mixing/clarifying tank, and the two-phase separation effect is better under stirring. The flow field is vortex flow near the blades in the mixing room, and this is agreement with the flow characteristic of rushton turbine. References | Related Articles | Metrics

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Dimensional analysis of interface fluctuation for new cathode structure of aluminum electrolytic cells Liu, Yan (1); Zhang, Ting-An (1); Zhang, Jun (1); Feng, Nai-Xiang (1) 2012, 33 (4):  563-566.  DOI: - Abstract ( 481 )   HTML   PDF (654KB) ( 667 )   The effect of anode gas on interface fluctuation was studied with cold water model experiment based on the principle of similarity. The behavior of interface fluctuation was investigated in the cold water model for the new cathode structure electrolytic cell. The criterion equation of amplitude, which is dependent on a variety of material properties, operating factors and equipment factors, was derived by dimensional analysis. According to the derived criterion equation, the effect of electrolyte level on interface fluctuation was theoretically analyzed to obtain the specific criterion equation. The solutions of criterion equation agree with the experimental results. References | Related Articles | Metrics

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Dynamic characteristics analysis based on finite element for automotive transmission coupling system Yu, Yin-Xin (1); Yuan, Hui-Qun (2); Zhang, Liang (1); Lu, Bing-Wu (3) 2012, 33 (4):  567-570.  DOI: - Abstract ( 508 )   HTML   PDF (945KB) ( 626 )   The finite element solid model of transmission was established by using the mixed finite element method of three-dimensional solid, spring-damper and coupling matrix elements, and the modal analysis of the transmission drive system and assembly was done below the third gear. The dynamic responses of the gear transmission system were computed under gear tooth time-varying stiffness, impact and manufacturing error excitations. The results showed that the transmission did not produce resonances under the specific condition of the third gear. There were many frequency components, such as fractional, double and modulation frequencies. The vibration responses displayed multi-period nonlinear characteristics. The research results may make a good foundation for the noise analysis and optimum design of the transmission. References | Related Articles | Metrics

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DNPSO-based support vector machine for engine fault diagnosis Nie, Li-Xin (1); Zhang, Tian-Xia (1); Zhang, Li-Ping (1); Guo, Li-Xin (1) 2012, 33 (4):  571-575.  DOI: - Abstract ( 701 )   HTML   PDF (845KB) ( 664 )   A dynamic neighborhood particle sware pattern was set on the basis of serial numbers and amount of neighboring particles. The optimum performances of six test functions were analyzed by the Taguchi DOE. The better change pattrens of the PSO parameters, such as inertia weight, number of the particle neighbors and acceleration coefficients, were selected. An optimization model of dynamic neighborhood particle swarm was built, which may have a wider adaptability and lower computation complexity. The penalty parameters and kernel function evaluation parameters of support vector machine were optimized with the proposed model. Compared with that of the BP ANN and SPSO-based SVM models, DNPSO-based support vector machine shows a better characteristics identification ability and higher robustness in the engine fault diagnosis. References | Related Articles | Metrics

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Synthesis of nano-hydrotalcite by mechanochemistry/crystallization Tan, Qi (1); Yin, Wan-Zhong (1); Liu, Lei (1); Li, Xiao-Li (1) 2012, 33 (4):  576-579+587.  DOI: - Abstract ( 581 )   HTML   PDF (933KB) ( 750 )   Nano-hydrotalcite (Mg6Al2 (OH)16CO3·4H2O) was synthesized by mechanochemistry/crystallization method using brucite, Al(OH)3 and Na2CO3. The effects of dry milling time, milling speed and ball to powder mass ratio on crystal structure of hydrotalcite were studied, and the crystal structure and morphology were characterized by XRD and FE-SEM. Increasing dry milling time, milling speed and ball to powder mass ratio are all beneficial to the formation of nano-hydrotalcite. Well crystallized hydrotalcite, with regular hexagon shape and average particle size of 40 nm, can be successfully synthesized under 6 h of dry milling time, 2 h of wet milling time, 250 r/min of milling speed and a ball to powder mass ratio of 50:1. However, impurity phases will be found in the products if the experiment parameters kept increasing after the optimum ones. References | Related Articles | Metrics

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Explosion limits of CBM at elevated pressure and temperature Li, Gang (1); Li, Yu-Feng (2); Yuan, Chun-Miao (1) 2012, 33 (4):  580-583.  DOI: - Abstract ( 558 )   HTML   PDF (553KB) ( 958 )   The explosion limits of CBM(coal-bed methane) were determined with the temperature respectively at 20, 60, 100, 150, 200°C and pressure respectively at atmosphere pressure, 100, 200, 300 kPa by using the self-developed experimental setup. The results showed that with the increase of the initial temperature and pressure, the upper limit of explosion limits will increase, but the lower limit of explosion limit will decrease, resulting in expanding of the scope of explosion limits and increasing of the risk. The effect of initial pressure and temperature on the upper limit of explosion limits is more obvious than that of the lower limit of explosion limits. The results are helpful for the determination of safety process parameters of CBM. References | Related Articles | Metrics

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Kinetic parameters of maize starch in nitrogen atmosphere Yuan, Chun-Miao (1); Li, Chang (1); Li, Gang (1); Zhang, Pei-Hong (1) 2012, 33 (4):  584-587.  DOI: - Abstract ( 1163 )   HTML   PDF (829KB) ( 2008 )   Thermogravimetric analysis was performed at heating rates of 5, 10, and 15°C/min in nitrogen atmosphere to determine the thermal degradation kinetic parameters of maize starch. There are three stages of weight loss in the whole thermal process. The start and end temperatures in each stage are different at different heating rates. The temperature range was 25 to 125~146°C in stage I. For stage II and III, the temperature was from 266~274°C to 341~373°C and 342~378°C to 427~520°C, respectively. There is an observable decomposition in stage II in which the corresponding activation energy is 324.3~355.9 kJ/mol and the reaction order is 1.6~2.1. The predicted values of weight loss agree with the experimental results. References | Related Articles | Metrics

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Complete flow marketing effects of supply chain financing platform in iron and steel companies Zhang, Zhi-Yong (1); Zhuang, Xin-Tian (1); Gao, Ming-Chun (1); Tian, Kun (1) 2012, 33 (4):  588-591.  DOI: - Abstract ( 572 )   HTML   PDF (153KB) ( 1168 )   The operational efficiency of the supply chain financing platform in Baosteel was studied empirically by applying a multi-level fuzzy comprehensive evaluation method. The results indicated that the comprehensive evaluation score of Baosteel's supply chain financing platform is 68.92, which means that the performance of the supply chain financing platform in Baosteel is satisfactory. The service quality index, operational benefit index, competition effect index and platform promotion index are 81.66, 74.72, 59.98, and 50.78 respectively, which means that the competition effect and the platform promotion need enhancing and elevating. Finally, some suggestions were given for the future development and improvement of Baosteel's supply chain financing platform. References | Related Articles | Metrics

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Evolution of generalized innovation network in industry clusters Huang, Wei-Qiang (1); Zhuang, Xin-Tian (1); Yao, Shuang (2) 2012, 33 (4):  592-596.  DOI: - Abstract ( 462 )   HTML   PDF (169KB) ( 767 )   Both the preference attachment and regional connection preference were considered in the process of network dynamic evolution. The evolution equation of network degree distribution was derived on the basis of the incremental equation method, which was used in the research of complex networks. The analysis results demonstrated that the innovation network degree distribution followed the power-law. The resource differences among the enterprises are getting larger and larger with the dynamic evolution of network, it brings more technology opportunities for enterprises and is propitious to the production and communication of new technologies. The more uniform the network embedment, the more advantageous to improve the innovation performances of the cluster. Innovation cooperation should be encouraged to optimize the network structure and to reduce the resource monopolization possibilities by few enterprises. References | Related Articles | Metrics

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Effect of retailers' countervailing power on product strategy of upstream enterprises Qi, Yong (1); Liu, Zhi-Hui (1); Su, Hui-Qing (1) 2012, 33 (4):  597-600.  DOI: - Abstract ( 474 )   HTML   PDF (142KB) ( 904 )   Under the vertical structure of a single upstream producer and downstream oligarch competition, a dynamic game model was constructed about the upstream producers' differentiated manufacturing strategy and the downstream retailers' competition of double oligarchies. The effects of the upstream producers' differentiated strategies on their own enterprise profits and consumers' utility level were analyzed with or without the retailers' countervailing power. The results indicated that when the retailers don't have the countervailing power, the upstream producers tend to manufacture complementary products to improve their enterprise profits. When one of the retailers owns the countervailing power, the more complementary a product is, the greater the upstream enterprise's profiti is. In addition, the effects of product strategy on the consumer utility was studied when the retailers' countervailing power existed. References | Related Articles | Metrics

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Internal relationship of action-oriented competency of knowledge workers Jia, Jian-Feng (1); Huang, Shan (2); Zhu, Zhu (3) 2012, 33 (4):  601-604.  DOI: - Abstract ( 522 )   HTML   PDF (493KB) ( 600 )   Baysesian network model method was adopted to obtain the optimized model of internal relationship of action-oriented competency of knowledge worker according to greedy algorithm, in which 85 searches were carried out. Three conclusions were drawn through the optimized model: influence cluster directly affects basic behavior cluster, action and target cluster and management cluster; action and target cluster doesn't affect the other three clusters, but they all affect action and target cluster; influence cluster not only directly affects action and target cluster, but also indirectly affects it respectively through management cluster and basic behavior cluster, in which the degree of direct influence was less than that of indirect influence. References | Related Articles | Metrics

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Curve characterization in 3D affine space Yu, Yan-Hua (1); Yang, Yun (1); Liu, Hui-Li (1) 2012, 33 (4):  605-608.  DOI: - Abstract ( 551 )   HTML   PDF (152KB) ( 1051 )   The structure equations of curves were studied in 3D affine space, and the invariants of space curves were discussed in the semi Euclid space. A space curve that is both in 3D Euclid space and 3D Minkowski space was considered, and two invariants were obtained which are curvature, torsion and moment of inertia dependent. It was verified that the two invariants are independent of the choice of inner products. References | Related Articles | Metrics