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15 August 2009, Volume 30 Issue 8 Previous Issue    Next Issue
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Stability of NCS with time-varying delay based on PI state feedback Dang, Xiang-Dong (1); Zhang, Qing-Ling (1) 2009, 30 (8):  1065-1068+1073.  DOI: - Abstract ( 294 )   HTML   PDF (2225KB) ( 620 )   Studies the modeling, exponential stability and controller design of networked control system (NCS) with both delayed transmission time and data packet dropout occurring between sensor, controller and actuator. The NCS with time-varying delay and data packet dropout based on proportional-integral (PI) state feedback is modeled as an asynchronous dynamical system (ADS) constrained by event rates. Based on the ADS theory, principle of Lyapunov stability and method of linear matrix inequality, both the negative semi-definite matrix condition for exponential stability and the PI state feedback controller design of NCS are presented. Numerical example showed that both are feasible. References | Related Articles | Metrics

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A rapid control prototyping system based on DSP Fang, Zheng (1); Zhang, Qi-Chun (1); Qi, Yu-Cheng (1) 2009, 30 (8):  1069-1073.  DOI: - Abstract ( 489 )   HTML   PDF (548KB) ( 1820 )   To shorten the periods required for developing control algorithms, improve the reliability of controllers and simplify the modification of control algorithms, a DSP-based rapid control prototyping (RCP) system was designed and developed. The RCP system is composed of a hardware controller with TI F2812DSP embedded in it and an integrated software development environment provided by MATLAB/Simulink. Through the Real-Time Workshop function of MATLAB, users can directly generate executable codes from Simulink model and download them into the DSP controller for real-time control, thus reducing developers' heavy programming tasks and enhancing the efficiency of R & D. A real-time control experiment was done for the intelligent PD controller with neural network and feedforward compensation to demonstrate the validity of the system. References | Related Articles | Metrics

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A new collaborative optimization based on genetic algorithm Li, Hai-Yan (1); Jing, Yuan-Wei (2); Zhang, Wen-Lei (1) 2009, 30 (8):  1074-1077.  DOI: - Abstract ( 373 )   HTML   PDF (277KB) ( 861 )   In view of that the feasible region is possibly inexistent during the collaborative optimization at system level, the genetic algorithm (GA) is introduced in combination with strengthening the constraint conditions step by step to develop a new GA-based collaborative optimization algorithm. In this algorithm the individual in feasibility in population is computed with the optimal values resulting from subsystems, then whether the solution to an individual is feasible depends on the infeasibility and its threshold. A method to adjust the threshold is proposed via cyclic iteration steps to ensure that the optimization at system level will go towards decreasing the unsatisfiability of constraint on consistency equality, thus achieving the goal to enhance the interdisciplinary consistency. Taking the design of a speed reducer as example, the performance of the optimization algorithm is proved excellent. References | Related Articles | Metrics

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Decentralized robust H∞ output feedback controller design based on homotopic algorithm Zheng, Hai-Qing (1); Jing, Yuan-Wei (1); Chen, Zhao-Na (1); Liu, Xiao-Ping (1) 2009, 30 (8):  1078-1082.  DOI: - Abstract ( 256 )   HTML   PDF (1988KB) ( 560 )   The design of decentralized H∞ output feedback controller for a class of time-delayed large-scale interconnected systems is studied, where the value bounded uncertainties are found in the state and control matrices. Based on a delay-dependent bounded real lemma, the condition under which a decentralized robust H∞ output feedback controller exists is derived and it is available to be attributed to a solution to the problem of nonlinear matrix inequality (NLMI) which can be expressed in terms of a homotopy function properly selected. Then, with the homotopic iteration method and the Schur complement lemma introduced, the solution can be converted into an iterative solution to the linear matrix inequality (LMI). The controller thus obtained enables the closed-loop large-scale system to be robust and asymptotically stable so as to satisfy the set H∞ performance indices. Simulation result verified the effectiveness of the method proposed. References | Related Articles | Metrics

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Hybrid modeling based on differential evolutionary algorithm for prediction of molten steel temperature Yuan, Ping (1); Mao, Zhi-Zhong (1); Wang, Fu-Li (1) 2009, 30 (8):  1083-1086.  DOI: - Abstract ( 269 )   HTML   PDF (242KB) ( 819 )   To predict the molten steel temperature in the smelting process of ladle furnace (LF), a hybrid model is proposed, where a BP neural network trained by an improved differential evolutionary algorithm (DEA) is introduced to determine the model parameters which are hard to exactly obtain by mechanism models. In the model, the mutation factor is randomly selected and the individuals in population are re-initialized in due time, thus rising above the difficulty efficiently in training BP neural network and avoiding the premature of DEA. Simulation results showed that the hybrid model has good precision of prediction for molten steel temperature and meets practical production requirements. References | Related Articles | Metrics

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A fast shadow detection algorithm for moving vehicles Wu, Cheng-Dong (1); Wang, Li (1); Zhang, Yun-Zhou (1); Liu, Meng (1) 2009, 30 (8):  1087-1090+1110.  DOI: - Abstract ( 266 )   HTML   PDF (1172KB) ( 642 )   Investigates the effect of change in ambient light on the outdoor traffic surveillance system, then a fast shadow detection algorithm is proposed for moving vehicles. According to the local shading model, in the algorithm the brightness ratios are used as criteria to detect the shadows preliminarily so as to get rid of the pseudo-shadow pixels by dynamic edge projection to obtain the approximate locations of relevant vehicles and, as a result, the thresholds of the criteria can be updated adaptively in compliance with the statistical histogram of brightness ratios. To verify the effectiveness of the proposed algorithm, some tests were done in situ with different scenes and sunlight conditions. The results showed that the proposed algorithm is fast in detection and accurate in ridding shadow without color drift due to change in ambient light. So, it is suitable for the outdoor vehicle detection system. References | Related Articles | Metrics

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A LEACH-based routing protocol for wireless sensor network to optimize QoS Wu, Cheng-Dong (1); Chen, Fei (1); Ji, Peng (1); Zhang, Yun-Zhou (1) 2009, 30 (8):  1091-1094.  DOI: - Abstract ( 289 )   HTML   PDF (341KB) ( 973 )   The density-constrained low-energy adaptive clustering hierarchy protocol, i.e., DC-LEACH, is proposed to meet the QoS requirement and minimize the energy consumption. Selecting the nodes in proper position as the clustering heads, the routing protocol reduces the energy consumption and alleviates the adverse effect on the communication quality, both resulting from the nonuniform distribution of nodes in network. In the protocol the probability analysis is made to fix the optimum measuring range in which the clustering heads are selected according to the threshold value of node density, thus giving the routing protocol of the network in clustering form. The simulation results showed that the improved protocol is able to not only reduce the energy consumption but also guarantee the communication quality. References | Related Articles | Metrics

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An image segmentation algorithm based on structure tensor and random walk Pian, Zhao-Yu (1); Gao, Li-Qun (1); Guo, Li (1) 2009, 30 (8):  1095-1098.  DOI: - Abstract ( 297 )   HTML   PDF (398KB) ( 1122 )   Proposes a new approach to image segmentation through combining the structure tensor with random walk algorithm. Taking advantages of the structure tensor, the weights between pixels are computed in terms of scale vector, then the image is segmented by the random walk algorithm. Because the weight used is in terms of scale vector, it can characterize the structure information so as to make the segmentation more accurately. In addition, an adaptively anisotropy filter function is proposed instead of the Gaussian function to smoothen the structure tensor, thus enabling the smoothened structure tensor to keep more information on image's complicated structure. The final experiments demonstrated that the proposed algorithm is more accurate and stable in image segmentation. References | Related Articles | Metrics

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On the vein image capturing system based on near-infrared image quality assessment Cui, Jian-Jiang (1); Wang, Li-Hui (1); Chen, Da-Li (1); Pan, Feng (1) 2009, 30 (8):  1099-1102.  DOI: - Abstract ( 528 )   HTML   PDF (335KB) ( 1051 )   According to the effect of image capturing on image processing, a near-infrared source control system was designed for the hand vein image capturing system. The different assessment methods for the gray-scale images resulting from near-infrared imagery and their different applications were discussed, based on the information capacity, energy spectrum-entropy and false signal-to-noise ratio. A method was therefore proposed to assess the vein images quality, with which the relationship between image captured and light intensity was investigated so as to deduce the relationship between image quality and LED current, thus obtaining the optimal light source control/modulation signal. Applying the results of image quality assessment to light intensity control, a light source system was designed to integrate the near-infrared image capturing and image quality assessment with light source control together. As a result, the vein images meet the requirements of subsequent processing. References | Related Articles | Metrics

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Brain-computer interface design based on relative wavelet energy Zhao, Hai-Bin (1); Wang, Hong (1); Li, Chun-Sheng (1) 2009, 30 (8):  1103-1106.  DOI: - Abstract ( 265 )   HTML   PDF (1141KB) ( 742 )   The feature extraction method using relative wavelet energy (RWE) is investigated for a brain-computer interface (BCI) based on two different mental tasks, i.e., the imaginary left and right hand movements. Discusses the computational method of RWE in depth, then RWE is used for the feature extraction of EEG signals with the support vector machine (SVM) used for classification. Classification accuracy and mutual information (MI) are taken as the evaluation criteria for BCI system. The off-line analysis results show that the maximum classification accuracy is 85.7% and maximum MI is 0.41 bit. Both are higher than the feature extraction characterized by the conventional adaptive autoregressive (AAR) coefficients. References | Related Articles | Metrics

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Classification of brain-computer interface signals based on common spatial patterns and K-nearest neighbors Ye, Ning (1); Sun, Yu-Ge (1); Wang, Xu (1) 2009, 30 (8):  1107-1110.  DOI: - Abstract ( 308 )   HTML   PDF (796KB) ( 1092 )   Brain-computer interface (BCI) refers to a communication/control channel between human and computer, which reflects human intention in the form of EEG signal then converts it into control signal. Two kinds of EEG signals of imaginary motions are classified, to which the feature extraction combining the wavelet packet decomposition (WPD) with common spatial pattern (CSP) is presented for EEG signals. Different wavelet packets are used to decompose the multi-channel EEG signals in training set, whereas CSP can extract the features of EEG signals from the subbands at different decomposed levels. Furthermore, the K-nearest neighbors (KNN) is used to classify the different features thus extracted to obtain the optimum wavelet function and relevant subband parameters which are used to classify test data. Simulation results showed that if the wavelet packet function is db4 with 4 decomposed levels and 8 feature points are selected, the highest classification accuracy can be up to 96%. References | Related Articles | Metrics

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A memetic algorithm for single-level capacitated lot-sizing problems Han, Yi (1); Tang, Jia-Fu (1); Wang, Li-Yan (1); Zhou, Gen-Gui (2) 2009, 30 (8):  1111-1114.  DOI: - Abstract ( 178 )   HTML   PDF (303KB) ( 746 )   A memetic algorithm (MA) is proposed combining GA's searching capability for breadth with that for depth so as to solve the multi-item single-level capacitated lot-sizing problems (CLSP) of the master production scheduling system, with the infeasible solutions to be dealt with the methods of capacity adjustment and penalty function. To eliminate overload, a "sequencing first, then reversing" strategy is used to adjust the capacity, i.e., checking if the overload occurs in the whole production process then reverse the process. The executive procedure of memetic algorithm is shown by a flowchart and its computation performance is tested and compared with other existing algorithms. Simulation results verified the feasibility and adaptability of the memetic algorithm proposed. References | Related Articles | Metrics

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On the algorithm of visualization of internet topology at router level Zhang, Jun (1); Zhao, Hai (1); Kang, Min (3); Fu, Da-Yu (2) 2009, 30 (8):  1115-1118.  DOI: - Abstract ( 290 )   HTML   PDF (377KB) ( 650 )   The visualization of Internet topology has been becoming a hot problem attracting the academic attention of complex network. The shortcomings of some existing algorithms were analyzed, then, a new algorithm was put forward by evolving the coreness of nodes from inside to outside. Starting the evolution from the center node, the algorithm finds out the nodes connected directly with the center node and arranges them around it, and the arranging range increases with decreasing coreness of nodes. Then, restarting the evolution from every leaf node, the nodes connected with the leaf node are found out and arranged around it. With the visualized data of the Internet topology at router level obtained from the Riesling monitor of CAIDA in May 2007 taken as example, the results show that the algorithm is beneficial to describe the hierarchies of Internet topology especially the inner cores. But, for the outer cores, its advantage is faint because of the fast increasing number of nodes. References | Related Articles | Metrics

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Group key management protocol based on bilinear pairing for multicast Liu, Xiu-Mei (1); Zhou, Fu-Cai (2); Chang, Gui-Ran (1); Xu, Hai-Fang (2) 2009, 30 (8):  1119-1123.  DOI: - Abstract ( 228 )   HTML   PDF (183KB) ( 835 )   Most of the ad hoc network group key management protocols are often improved in some respects at a great cost in other respects, since there is a contradiction between bandwidth and computation resources in ad hoc network. A new distributed group key management protocol is therefore proposed and named TPAN protocol, i.e., a tree-based group key agreement using bilinear pairing for mobile ad hoc networks, which combines the merits of both PSTR and PTGDH together. In TPAN the PSTR key tree is taken as the trunk with the PSTR or PTGDH protocol as branches or sub-trees. The communication costs and calculating costs of different protocols are compared with each other and their security is analyzed, and the results show that the TPAN protocol can achieve the balance between computation costs and communication costs with low costs and security provided. References | Related Articles | Metrics

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Hot deformation behavior of duplex stainless steels Fang, Yi-Liu (1); Cheng, Yi-Ming (1); Wang, Yue-Xiang (1); Liu, Zhen-Yu (1) 2009, 30 (8):  1124-1126.  DOI: - Abstract ( 256 )   HTML   PDF (460KB) ( 791 )   The hot deformation behavior of the austenite-ferrite duplex stainless steels 00Cr22Ni5Mo3N and 00Cr22Ni1Mo0.7N were investigated experimentally in the temperature range from 1000 to 1200°C and at the strain rates from 0.01 to 30 s-1 by hot compression tests. With the experimental data, two relevant equations of hot deformation were given, where the activation energy was 534 kJ/mol and 482 kJ/mol, respectively. It was found that the optimum regions for hot working are of comparatively high temperature and low strain rate, where the fully dynamic recrystallization/recovery of austenite and ferrite come to pass during hot deformation, while in the regions of comparatively low temperature and high strain rate, the microstructure exhibits intense flow localization, even cracks observable during deformation. References | Related Articles | Metrics

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Effect of annealing process on microstructure and properties of Al-carbon steel-Al sandwich strip by roll cladding Zu, Guo-Yin (1); Wang, Lei (1); Wang, Wei (1); Yu, Jiu-Ming (1) 2009, 30 (8):  1127-1130+1134.  DOI: - Abstract ( 355 )   HTML   PDF (676KB) ( 881 )   The annealing process of the Al-carbon steel-Al sandwich strip produced by roll cladding was investigated. The effects of annealing temperature/time on the growth behavior of interfacial intermetallics were analyzed by metalloscope, SEM and XRD with the main mechanical properties tested. The results showed that the critical forming temperature of the intermetallics is 420°C, at which the main compound is of FeAl3 phase and the layer thickness is about 10μm. The optimum annealing schedule obtained from testings is 420°C for 20 min. The elongation of the strip after annealing comes up to 18.28% and, however, it will be lower than 5% if the brittle intermetallics distribute continuously on interfaces. References | Related Articles | Metrics

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On hydraulic model for 180 t LF process Dou, Li-Wei (1); Yu, Fu-Zhi (2); Shen, Feng-Man (1) 2009, 30 (8):  1131-1134.  DOI: - Abstract ( 387 )   HTML   PDF (307KB) ( 726 )   A hydraulic model was developed according to the similarity principle to study the fluid flow in a 180 t ladle furnace (LF) in a certain steelmaking plant. The effects of such operation parameters as bottom blowing position, charging position and argon flowrate on the homogenization condition of molten steel in ladle were investigated, thus grasping how those parameters affect the homogeneity of molten steel. Taking account of the physical phenomena occurring in the hydraulic model test and other factors comprehensively, the optimal operation parameters for an 180 t ladle furnace were obtained, i.e., the ladle bottom blowing position is approximately 30% of the radius from the cylindrical center, the charging position is just above the bottom nozzle and the argon flowrate of bottom blowing is approximately 40-90 m3/h. The best sampling point after LF refining and composition microadjustment is the charging position, and the sampling operation shall be done after stirring for at least 2 min. References | Related Articles | Metrics

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Application of inverse solution to boundary of heat transfer in erosion diagnosis of blast furnace hearth Chen, Liang-Yu (1); Li, Yu (1); Wang, Zi-Jin (2); Zhang, Ming (2) 2009, 30 (8):  1135-1138.  DOI: - Abstract ( 296 )   HTML   PDF (1191KB) ( 787 )   Based on the principle of the inverse solution to the undetermined boundary in complex heat transfer problem, a numerically stepwise approximation method was formed to calculate the erosion boundary values of the lining for blast furnace hearth via the procedure of regular solution-approval-boundary modification-secondary regular solution/approval. The method was formed in case there are only few even no temperature measuring points in blast furnace hearth and under the approved conditions that the measured temperature and heat flux in cooling stave are taken as erosion boundary values according to the axisymmetric steady-state heat transfer equation. On the principle of maximum risk, the method judges the non-uniqueness and ill-posed condition of the erosion profiles of axial lining sections so as to diagnose the blast furnace hearth and bottom. The diagnosis result was regarded as consistent with the overhaul results. The method proposed can be applied to erosion diagnosis of congeneric blast furnace hearth. References | Related Articles | Metrics

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Study on basic sintering properties of iron ores in ANSTEEL Shang, Ce (1); Zhou, Ming-Shun (2); Zhai, Li-Wei (2); Shen, Feng-Man (1) 2009, 30 (8):  1139-1142.  DOI: - Abstract ( 418 )   HTML   PDF (338KB) ( 887 )   The basic sintering properties of iron ores were investigated experimentally by miniature sintering setup and pot, and evaluated comprehensively, such as assimilability of iron concentrates, strength of liquid consolidation, fluidity of liquid phase, capability of crystal stock. Then, a rule of reasonable batching by weight for sintering was found and applied to practical production. The results showed that in the sintering process the batching mainly depends on the concentrates B and D mixed with C, while in the pelletizing process the concentrate A is principal in ANSTEEL. The ironmaking technical-economic indices are thus improved obviously after optimizing and readjusting the batching, e.g., the BF utilization coefficient increases by 0.043 (t/m3·d), and the coke ratio decreases by 5.28 kg/t with sinter cost being reduced by 2.2¥/t. References | Related Articles | Metrics

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Numerical simulation of molten metal flow behavior under the action of traveling magnetic field Wang, Fang (1); Li, Bao-Kuan (1); Shen, Feng-Man (1) 2009, 30 (8):  1143-1146.  DOI: - Abstract ( 297 )   HTML   PDF (1143KB) ( 777 )   Combining the theory of traveling magnetic field with the Navier-Strokes equation for fluid motion, a mathematical model was developed for the 3-D flow field in a cylindrical container to prepare metallic materials under the action of traveling magnetic field. In addition, a new model was introduced to compute the electromagnetic force. It was found through comparison that the modeling results is in accord with the experimental results made by Gerbeth, thus verifying the reliability of the model developed and relevant computation program. When the aspect ratio decreases, the flow field structure in container has no change, i.e., the two symmetric vortices remain unchanged, but their shapes change to rectangular from elliptic. When the electromagnetic force increases, the axial velocity curve changes to steeple parabola from flat one and the stronger the electromagnetic force, the shorter the distance between wave apex and container bottom surface. References | Related Articles | Metrics

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Physical simulation of mass transfer phenomena on slag-metal interface Yang, Chun-Guang (1); Li, Qiang (1); Zou, Zong-Shu (1) 2009, 30 (8):  1147-1150.  DOI: - Abstract ( 323 )   HTML   PDF (1089KB) ( 617 )   On the condition that the oil-water phase contact area was kept constant at room temperature, a model experiment was done on a 3-D tubular reactor using diesel engine oil and water to simulate the slag and steel, respectively, thus investigating the mass transfer phenomena by taking the advantage of sodium benzoate as a tracer that is soluble in both water and nonvolatile oil. Changing the circulating water flow rate uninterruptedly, the mass concentration of sodium benzoate in water was measured by the PH-3G conductivity meter to calculate the mass transfer rate. Based on the double membrane theory, the restrictions on mass transfer of sodium benzoate in the oil-water two phase boundary layer were judged with the equilibrium distribution ratio calculated. Furthermore, the diffusion coefficient of sodium benzoate in water was obtained on the basis of binary liquid kinetics theory, and the dimensionless number equation to determine the Reynolds, Sherwood and Schmidt numbers were given under the experimental conditions. References | Related Articles | Metrics

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Numerical simulation of new-type EMBR for flow field in funnel shape mold Tian, Xi-Yan (1); Li, Ben-Wen (1); He, Ji-Cheng (1) 2009, 30 (8):  1151-1154.  DOI: - Abstract ( 284 )   HTML   PDF (502KB) ( 735 )   A new-type EMBR (electromagnetic brake) was specially designed for the funnel shape mold during thin slab casting because of the irregularity of the wide walls of such molds. Numerical simulations were carried out to predict the liquid steel flow under the action of the EMBR of which the positional height and magnetomotive force (the number of winding turns multiplied by the current passing through the winding) have both been changed. The results showed that the two changed parameters have slight influence on the trend of magnetic field distribution, and the distribution is heterogeneous in mold. And it was found that the region where the magnetic induction is maximum is slightly below the center of magnetic field and close to the inner surface of narrow wall of the mold. Compared with the mold without electromagnetic force exerted on it, the results showed that the liquid steel flow strands can be inhibited so as to improve the flow field greatly if the height of the new-type EMBR is in the range from 250 mm to 300 mm and the magnetomotive force are 8000 A or higher. References | Related Articles | Metrics

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Experimental study on the atomization behavior of fuel injector group of a heavy-duty gas turbine Liu, Kai (1); Cai, Jiu-Ju (1); Zhang, Bao-Cheng (2); Ma, Hong-An (2) 2009, 30 (8):  1155-1158.  DOI: - Abstract ( 372 )   HTML   PDF (410KB) ( 942 )   The atomization behavior of the fuel injector group in the combustion chamber of a Grade E heavy-duty gas turbine was experimentally investigated and the results were discussed. Applying the LDV/PDPA system supplied by TSI Co. to measuring the atomized particle size from the fuel injector group and its distribution under different pressures, the spray cone angle was given by relevant recognition software. The results showed that the atomized particle size is sensitive to pressure. For instance, the particle size decreases from 23.32 to 10.11μm with the pressure increasing from 0.4 to 1.2 MPa, whereas the spray cone angle decreases to 69.5° from 73.5°. Those experimental data provides a reliable basis for the design and R& D of injector group. References | Related Articles | Metrics

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Modeling investigation on decarburization process in RH refining system under the action of rotating electromagnetic field Qi, Feng-Sheng (1); Li, Bao-Kuan (1); Chen, Hai-Geng (1) 2009, 30 (8):  1159-1162.  DOI: - Abstract ( 367 )   HTML   PDF (1202KB) ( 592 )   A mathematical model was developed to investigate the molten steel flow and decarburization process in RH vacuum degasser system under the action of electromagnetic field. A modified homogeneous flow model was introduced to calculate the flow field in RH degasser, thus getting rid of some earlier methods that are unavailable to be generalized, such as reducing the computation region or presetting the distribution of gas volume fraction. The RH system with and without rotating magnetic field were simulated, and the numerical results showed that the flow field and decarburization process are in agreement with the experiment results in some earlier works. At the early stage of the decarburization reaction, when magnetic flux density is 0.04T the decarburization rate of RH system with electromagnetic stirring is 15% higher than that without electromagnetic stirring because the vortex due to the stirring enhances the stirring power hence the decarburization rate. Finally, the carbon contents under different magnetic flux densities tend to the same stable value. References | Related Articles | Metrics

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Dry granulation experiment of blast furnace slag by rotary cup atomizer Yu, Qing-Bo (1); Liu, Jun-Xiang (1); Dou, Chen-Xi (1); Hu, Xian-Zhong (1) 2009, 30 (8):  1163-1165+1173.  DOI: - Abstract ( 389 )   HTML   PDF (385KB) ( 1383 )   A dry granulation experiment was done by means of a rotary cup atomizer for blast furnace slag instead of the currently used water quenching process because it is unable to efficiently recover the waste heat energy inside the molten slag. The influences of cup atomizer rotating speed, its diameter and molten slag temperature on the mean slag granule diameter and granules' mass distribution were investigated. The results showed that the mean granule diameter decreases with increasing rotating speed which will lead the slag granules to be far from the cup so as to make their mass distribution more uniform. The rotating speed 1000 r/min is actually a criterion, i.e., the mean granule diameter decreases with increasing cup diameter if lower than it, while the diameter is almost unchanged if higher than it. And the molten slag temperature has no influence on mean granule diameter and mass distribution of granules. References | Related Articles | Metrics

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Study on roasting process of diasporic bauxite Wang, Yi-Yong (1); Zhang, Ting-An (1); Bao, Li (1); Jin, Hui (1) 2009, 30 (8):  1166-1169.  DOI: - Abstract ( 370 )   HTML   PDF (594KB) ( 1237 )   An activating roasting process of Chinese diasporic bauxite was tested by muffle to lower the digestion temperature in Bayer process. The effects of operation parameters such as roasting temperature/time on the digestibility of the diasporic bauxite were investigated, and the digestibilities of the activated roasted ore and raw ore were compared with each other. The microstructure and morphology of roasted ore were characterized by SEM. The results showed that the optimal roasting temperature/time is 585°C for 60 min, and under such roasting conditions the digestion temperature of roasted ore decreases by 40°C in comparison with that of the raw ore when the digestibility comes up to the same maximum value. References | Related Articles | Metrics

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Characteristics of frequency capture of nonlinear vibration systems Zhang, Nan (1); Hou, Xiao-Lin (2); Wen, Bang-Chun (1) 2009, 30 (8):  1170-1173.  DOI: - Abstract ( 411 )   HTML   PDF (578KB) ( 853 )   Based on a simplified model of a self-synchronous mechanical system, the influence of system damping on the steady-state rotational speed of non-ideal system is analyzed, including vertically translating damping and eccentric rotor's rotary damping. Changing both dampings separately, the system responses and frequency spectra are obtained on different conditions, as well as the capture regions of high-order harmonic frequency and subharmonic frequency because of the piecewise change in translating damping and in rotary damping, respectively. It is revealed that the capture of high-order harmonic frequency occurs if the translating damping value is appropriate, and that of subharmonic frequency occurs if the rotary damping value is appropriate. References | Related Articles | Metrics

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Sensitivity analysis of nonlinear stiffness vibration transmission path system Zhao, Qun (1); Zhang, Yi-Min (1); Zhao, Jin-Fang (1) 2009, 30 (8):  1174-1177.  DOI: - Abstract ( 369 )   HTML   PDF (421KB) ( 927 )   Aiming at the nonlinear problem of the vibration transmission path system, a mechanics model is developed according to the powerflow theory and four-end parameter analysis so as to obtain the system responses and powerflow characteristics of a vibration transmission path system. The equivalent stiffness and isolator mobility are studied when the material's nonlinear stiffness and piecewise linear stiffness both exist in the system. The sensitivity of the system powerflow to the isolator damping and the sensitivity to both material's nonlinear stiffness and piecewise linear stiffness are discussed, thus giving the sensitivity of system characteristics to those parameters with the sensitive region clearly shown. As a result, how the system parameters contribute to the system powerflow is presented visually so as to guide the optimization of system architecture. References | Related Articles | Metrics

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A centroid-based method of planar mechanism path indirect synthesis Wang, Dan (1); Liu, Yang (1); Wang, Xiao-Guang (1) 2009, 30 (8):  1178-1180+1184.  DOI: - Abstract ( 325 )   HTML   PDF (266KB) ( 558 )   The indirect way to implement the mechanism path synthesis is mainly to match the expected path curve with the present curve in path atlas through comparison, then extract the mechanism corresponding to these curves. It is of significance to the innovative design of mechanisms. A centroid-based method is proposed to analyze the path curves. After rotating, translating and scaling down/up, the path curve image is normalized in an area of 21 × 21 pixels, thus solving the key technological problem of coding the image. Furthermore, matching similar images on the principle of fuzzy recognition will enable the mechanism path to be indirectly synthesized quickly and easily. The centroid-based method is proved effective and reasonable, and the accuracy of calculating the path can be improved by way of lengthening the standardized character string after path curve processing. References | Related Articles | Metrics

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Approach to improving transmission efficiency of MBCVT for automobiles Zhang, Wei-Hua (1); Gong, Yun-Peng (1); Cheng, Nai-Shi (1); Li, Shu-Jun (1) 2009, 30 (8):  1181-1184.  DOI: - Abstract ( 327 )   HTML   PDF (269KB) ( 1548 )   Analyzes the reason why the efficiency of the metal belt continuously variable transmission (MBCVT) is not as high as it should be at present. It was found that the pulley thrust of existing MBCVT is determined according to the maximum torque transmitted, thus leading to the pulley thrust to be excessive with greatly increased energy consumption in hydraulic system. The transmission efficiency of metal belt transmission as the core part of MBCVT was investigated experimentally, and the dependence of torque transmitted on the slip ratio and transmission efficiency was obtained. Based on the experimental results, an approach was proposed to specify the pulley thrust in accordance with the actually transmitted torque, i.e., the pulley thrust should be regulated with the slip ratio in the range from 9.6% to 10.9%, thus providing the torque ratio range from 0.8 to 0.9, in which the metal belt transmission works restrictively. In this way, the MBCVT has the strongest transmission ability with the highest transmission efficiency, and decreases the pulley thrust by 10%-46% with fuel consumption decreased by 5%-8%. References | Related Articles | Metrics

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Calculating strain rate and strain during orthogonal cutting in accordance to streamline theory Bi, Xue-Feng (1); Liu, Yong-Xian (1); List, Gautier (2); Liu, Yang (1) 2009, 30 (8):  1185-1188.  DOI: - Abstract ( 390 )   HTML   PDF (1489KB) ( 747 )   The plastic deformation of metal during orthogonal cutting was analyzed according to the streamline theory in fluid mechanics, with a general streamline model introduced. The geometrical parameters in this model were determined by fitting the flow lines traced in experiments with the streamline model. Then, the distribution of strain rate in primary shear zone was calculated via combining the streamline analysis with plasticity theory. The results revealed that the distribution thus calculated conforms to the experimental results in earlier works, i.e., the streamline model is available to analyze the plastic deformation during metal cutting. The distribution of strain in primary shear zone is given by numerical integration. A new method is therefore proposed defining the shape of shear zone in accordance to the results of strain. References | Related Articles | Metrics

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Preparation of homogeneous CWAO catalysts to treat dyeing-printing wastewater Zhang, Yong-Li (1); Li, Liang (1); Hu, Xiao-Min (1) 2009, 30 (8):  1189-1192.  DOI: - Abstract ( 331 )   HTML   PDF (984KB) ( 821 )   To prepare the CWAO catalysts to treat high-concentration dyeing-printing wastewater, an experiment was done to degrade the methylene blue aqueous solution as sample, of which the COD value is up to 2000 mg·L-1, with homogeneous CWAO process. The performance of those catalysts was evaluated with COD removal rates and decoloring rates. Among the 19 kinds of soluble salts, some double-component catalysts were chosen and resynthesized. The results showed that the leading catalytic activity is of copper/iron salt, while the Cu1Fe1 catalyst resynthesized by copper sulphate and ferrisulphas is superior in both activity and cost and its COD removal rate in the sample wastewater increases by about 50% in comparison to that without the catalyst used. The mechanism analysis of Cu1Fe1 catalyst shows that the free-radicle reaction and coagulation of Fe (III) polymer both function simultaneously. References | Related Articles | Metrics

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Experimental study on different rock locating algorithms with acoustic emission Liu, Jian-Po (1); Wang, Hong-Yong (2); Yang, Yu-Jiang (1); Li, Yuan-Hui (1) 2009, 30 (8):  1193-1196.  DOI: - Abstract ( 461 )   HTML   PDF (464KB) ( 1289 )   Acoustic emission (AE) locating technique was applied to studying the 3-D evolutionary process of micro-cracks during different rock (granite/sandrock) failures under different loading conditions. The locating principles of both Geiger algorithm and simplex algorithm were analyzed with their locating accuracies comparatively discussed through experimental verification. The results showed that locating an event by acoustic emission can visually reflect the whole dynamic process from initiation and propagation to breakdown of micro-cracks, just like the process of rock failure. The locating accuracy of simplex algorithm is higher than Geiger algorithm but, as to the number of locating events by AE, the latter is more than the former. However, when studying the instability and failure process of rock by AE locating technique, what algorithm is feasible should be decided as the case may be. And two or more locating algorithms are simultaneously available to compare then analyze the results so as to get more accurate findings. References | Related Articles | Metrics

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Experimental study on change in acoustic wave velocity when rock is loading Zheng, Gui-Ping (1); Zhao, Xing-Dong (1); Liu, Jian-Po (1); Li, Yuan-Hui (1) 2009, 30 (8):  1197-1200.  DOI: - Abstract ( 392 )   HTML   PDF (374KB) ( 1348 )   Different rock samples were loaded up to explore the response characteristics of the acoustic wave velocity (AWV) in rock with stress changing. The testing results showed that the relationship between AWV and stress goes up linearly in the linear elastic load phase of granite and gneiss, and the relationship becomes nonlinearly quadratic if AWV comes up to its peak value and, finally, rock failure comes true if loaded further. As to the marble and sandstone, AWV keeps constant basically in the whole loading process. The AWV change in rock could be divided into two types according to the diagenesis of different rock, i.e., Type I: linear increasing-peak AWV-slow decreasing-abrupt decreasing (failure); Type II: keeping constant-abrupt decreasing (failure). It means that under cycling load AWV goes up linearly in elastic load phase then goes down abruptly if the load is increased to a certain extent and, further, rock failure happens. The reason why the AWV increases during elastic load phase is mainly due to density variation in rock samples. The process from initiation and propagation to breakdown of micro-cracks directly affects the rule of AWV change with stress. References | Related Articles | Metrics

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Optimizing cable tension during construction and completion of a cable-stayed bridge Zhang, Wen-Xian (1); Liu, Xu-Guang (1); Li, Dong-Wei (2); Ou, Dan (1) 2009, 30 (8):  1201-1204.  DOI: - Abstract ( 459 )   HTML   PDF (603KB) ( 1201 )   To rationally optimize the cable tension in the construction process of a cable-stayed bridge so as to realize the idea of design, the software MIDAS/Civil was used for FEA to a cable-stayed bridge being constructed. Then, the cable tension during construction and completion of the bridge was calculated through numerical simulation. With the methods of rigid support continuous beam, zero-displacement and bending energy minimization used separately to determine the initial cable tension under the dead load, the different results were compared with each other and supposed that using a single method mentioned above to optimize the cable tension is significantly limited. A comprehensive method is therefore proposed to calculate the cable tension, by which a favorable optimization result is available. Each construction step is simulated by the orderly-erecting analysis, then the relevant time-dependent cable tension curve was plotted to control the construction process of the bridge, thus providing a satisfactory effect. References | Related Articles | Metrics

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A grey-correlated analysis of critical influencing factors on supervisory board's governance Gao, Fei (1); Li, Kai (1); Wang, Shi-Quan (1) 2009, 30 (8):  1205-1207+1212.  DOI: - Abstract ( 214 )   HTML   PDF (181KB) ( 848 )   The critical influencing factors on the supervisory board's governance were found out by the gray correlated analysis. Then, the structural/operational characteristics of a corporate supervisory board were discussed with such variables as independence, initiative and efficiency selected to measure the governance feature. And the percentages of shareholder supervisors, staff supervisors and independent supervisors were selected to measure the personnel nature, with the level of financial supervision, the governance indices of the board of directors, all executives and stakeholders and information disclosure index selected to measure the supervision performance. The results revealed that the efficiency among all of governance feature indices especially the percentage of shareholder supervisors among personnel nature indices greatly affect the supervision performance. Therefore, the key to improve the performance of supervisory board's governance of all Chinese listed companies at present is to enhance the efficiency of supervisory board's governance and shareholder supervisors' participation in the governance. References | Related Articles | Metrics

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Robust Stackelberg game of supply chain under unknown demand distribution information Qiu, Ruo-Zhen (1); Huang, Xiao-Yuan (1) 2009, 30 (8):  1208-1212.  DOI: - Abstract ( 357 )   HTML   PDF (1485KB) ( 772 )   Studies the robust Stackelberg game of supply chain based on uncertain demand. A two-stage supply chain system is considered, where the supplier and retailer play the roles of leader and follower in deciding the wholesale price and order quantity, respectively. This problem is regarded as the expected value of distribution information on demand. The decisions for robust order quantity and wholesale price of centralized and decentralized supply chains are deduced under the conditions that only the information on the mean and variance of demand has been known, and the profits of supply chain and its members are analyzed according to the decisions. A numerical calculation was done to verify the effectiveness of the robust Stackelberg game of supply chain if the definite distribution of demand has been known. The result showed that the robust ordering strategy will reduce the profit from centralized supply chain to a certain extent, while the robust Stackelberg game will increase the profit from decentralized supply chain. References | Related Articles | Metrics

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Preconditioned SOR-type iterative methods for solving linear systems Shen, Hai-Long (1); Zong, Yuan (2); Shao, Xin-Hui (1) 2009, 30 (8):  1213-1216.  DOI: - Abstract ( 373 )   HTML   PDF (154KB) ( 1171 )   A new iterative method is suggested for large linear equation sets including the undetermined parameter and preconditioner, named the preconditioned SOR-type iterative method. The method becomes the preconditioned Gauss-Seidel type iterative method given by Cheng Guang-hui if ω = 1. When the coefficient matrix is irreducible Z-matrix, the iterative matrices of SOR method and preconditioned SOR-type iterative method are both Z-matrices as well, and their spectral radii are compared with each other via relevant theorem with the range of fetching parameter values given for the quickest convergence. Moreover, the preconditioned SOR iterative method is compared with the preconditioned Gauss-Seidel iterative method, and the result indicates that the former is superior to the latter. Numerical examples show that the proper choice of preconditioner can make the preconditioned SOR-type iterative methods more efficient in solving linear systems. References | Related Articles | Metrics