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15 August 2010, Volume 31 Issue 8 Previous Issue    Next Issue
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Pinning synchronization of a class of weighted complex dynamical networks with time delay Zheng, Hai-Qing (1); Jing, Yuan-Wei (1); Liu, Xiao-Ping (1) 2010, 31 (8):  1065-1069.  DOI: - Abstract ( 278 )   HTML   PDF (283KB) ( 511 )   The problem of global synchronization was studied for a class of complex dynamical networks composed of Lur'e systems. With the feedback strategy applied to a small part of the nodes in a large-size network, all the nodes in the whole weighted time-delay network become synchronous. Based on the absolute stability theory, the delay-independent and delay-dependent asymptotical stability criteria are derived separately to ensure the global synchronization of a network. In some particular cases, the synchronization of whole network is available only if pinning the control on a single node in the network. Numerical simulation results verified the effectiveness of the conclusion as above. References | Related Articles | Metrics

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A robust stabilization method for uncertain linear systems with time-delay Zheng, Lian-Wei (1) 2010, 31 (8):  1070-1073.  DOI: - Abstract ( 230 )   HTML   PDF (1424KB) ( 675 )   The robust stabilization for uncertain linear systems with time-delay is investigated by Lyapunov functional approach. The uncertainties are assumed to be norm-bounded and time-varying matrices. An inequality between Schur complements of two symmetric matrices is established. Then, an inequality for the upper bound of uncertain quadratic functions is obtained to estimate the Lyapunov functional derivative. Estimating the uncertain quadratic functions and performing some matrix manipulation, the negativity of Lyapunov functional is converted into a feasibility problem of linear matrix inequalities, thus giving a sufficient condition for robust stabilization. Meanwhile, the gain matrix of a robust state feedback controller is constructed via the solutions of the linear matrix inequalities. Numerical examples showed the robust stabilization method obtained in this way is less conservative. References | Related Articles | Metrics

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Impact of distributed generation on static voltage profile in distribution networks Sun, Qiu-Ye (1); Li, Zhong-Xu (1); Yang, Jun (1); Yang, Dong-Sheng (1) 2010, 31 (8):  1074-1077.  DOI: - Abstract ( 248 )   HTML   PDF (293KB) ( 584 )   The static voltage profile of loaded nodes in a radially chained distribution network interconnecting with a number of distributed generation (DG) systems was studied. Three typical load distribution models, i.e., the decreasing, increasing and isosceles models, were developed to discuss the voltage profile in such a distribution network quantitatively in association with the restrictions on DG's location and capacity. A simulation example was given to investigate the impact of DG's location and capacity on the static voltage, and the results showed that the interconnections between DGs and distribution network will support the voltage, while the improper location and capacity of DG may cause overvoltage and increase the network loss. Therefore, a reasonable allocation is necessary for DGs to ensure that the static voltage of every loaded node is within the permissible range. References | Related Articles | Metrics

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An improved algorithm based on boundary normal vector overlap for suspected pulmonary nodule extraction Luan, Guo-Xin (1); Wei, Ying (1); Xue, Ding-Yu (1) 2010, 31 (8):  1078-1081.  DOI: - Abstract ( 214 )   HTML   PDF (257KB) ( 629 )   An improved boundary normal vector overlap algorithm based on local shape constraint and adaptively defined normal vector magnitude is proposed to detect suspected pulmonary nodules. The original region of interest(ROI) is segmented with adaptive thresholding method in pulmonary parenchyma, then the local convex-concave shape feature is gained for every pixel of initial ROI boundaries to satisfy the calculations of normal vector direction and adaptively defined normal vector magnitude of every convex pixel on the initial ROI boundaries. Overlapping the normal vectors, the locally maximum overlap can be chosen so as to detect the suspected round pulmonary nodules of different sizes. The restriction due to the local convex-concave shape feature should be taken into account before overlapping the normal vectors, thus simplifying the calculation of overlap. The adaptively defined normal vector magnitude is available to get rid of the limitation of fixed-size nodules as the result of detection. Experiment results indicated that the improved algorithm can detect suspected pulmonary nodules effectively and applicable to the nodules of any sizes. References | Related Articles | Metrics

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A new algorithm of quick face tracking based on motion estimation Zhang, Yang (1); Ye, Shu-Fan (2); Gao, Li-Qun (1) 2010, 31 (8):  1082-1085.  DOI: - Abstract ( 356 )   HTML   PDF (895KB) ( 907 )   A new method for face detection and tracking in sequential moving state was proposed. The FloatBoost algorithm was used for face detecting to enhance its speed and accuracy. Then, based on the theory of kinematics and motion estimation, the motion averaging method and exponential smoothing method in time-series analysis were used to predict the moving location area of tracking object in next frame image so as to reduce the searching region and decrease the consumption of processing resource, thus implementing the real-time tracking effect. In the face detecting/tracking simulation by MATLAB the algorithm proposed was compared with the FSA and CPME algorithms in respect to the time required for tracking an object, and the results showed that the former is superior to the latter two in real-time response and accuracy. References | Related Articles | Metrics

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Improved algorithm for independent component analysis Ji, Ce (1); Yu, Yang (1); Yu, Peng (1) 2010, 31 (8):  1086-1088+1097.  DOI: - Abstract ( 317 )   HTML   PDF (1093KB) ( 692 )   The basic theory of independent component analysis (ICA) and the FastICA algorithm are briefly described. Conventional FastICA algorithm has only a second-order convergence rate, which has to be improved to reduce the iteration steps and running time. An improved ICA algorithm is therefore proposed, i.e., the Newton's iteration method with a fifth-order convergence. It is actually a modified Newton's iteration method to enable the improved FastICA algorithm to have fifth-order convergence rate. The simulation results of separating an image signal from others showed that although the algorithm thus improved has the same separating effect as conventional FastICA algorithm, it can greatly reduce the iteration steps and running time further than FastICA, thus increasing the convergence rate and improving the operation efficiency. References | Related Articles | Metrics

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On the batch loading and parallel scheduling problem during roller heat-treatment Song, Ji-Wei (1); Tang, Jia-Fu (1) 2010, 31 (8):  1089-1092.  DOI: - Abstract ( 284 )   HTML   PDF (913KB) ( 529 )   The batch loading and parallel scheduling (BLPS) with the identical heating furnace for roller heat-treatment was considered for the relevant cast steel plant. A mathematical model of BLPS was developed to minimize makespan. Then, a two-stage heuristic algorithm was proposed combining both the heuristic algorithms for roll billet batching and batch scheduling together, thus solving the model. The effectiveness of the method has been verified in comparison with simulation results. Furthermore, the solution to the BLPS problem is optimized on different scales to improve the productivity of rollers, which will benefit the decision-makers by scheduling the roll production reasonably. References | Related Articles | Metrics

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Efficient ontology matching processing in pure peer-to-peer network Zhang, Qian (1); Zhang, Xia (1); Zhao, Li-Jun (1); Liu, Zheng (3) 2010, 31 (8):  1093-1097.  DOI: - Abstract ( 301 )   HTML   PDF (339KB) ( 521 )   Most of the existing peer-to-peer (P2P) systems suffer from the lack of the support for semantic contents, thus making them unsuitable for knowledge sharing. To solve the problem, a prospective method is suggested, introducing ontology to describe the resources to be shared in P2P systems semantically. In a pure P2P environment, where the different peers are keeping up their characteristics of locally ontological heterogeneity individually, an HOM (history-based ontology matching) method is proposed on the basis of historical query logs. Mining the possible mapping relationship between different ontological concepts from historical query logs, the proposed method applies VSM to the recognition of the possible linguistic relationship between ontological concepts. Then, the mapping relationship between concepts is corrected to match the ontological concepts between different peers. Analytic and experimental results show that, compared with the existing methods, the HOM method considers the autonomy of peers and is more precise on matching different ontology. References | Related Articles | Metrics

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CSP/SVM-based EEG classification of imagined hand movements Liu, Chong (1); Zhao, Hai-Bin (1); Li, Chun-Sheng (1); Wang, Hong (1) 2010, 31 (8):  1098-1101.  DOI: - Abstract ( 1779 )   HTML   PDF (307KB) ( 2269 )   For the BCI (brain-computer interface) to classify the different imagined movements of both left and right hands, the method of CSP (common spatial pattern) was used to extract the features of BCI 2003 competitive dataset. Then, the CSP based on a sliding time window was used to filter the EEG(electroencephalogram) data from the electrodes C3, Cz and C4, with the SVM (support vector machine) used as a classifier of the features. As a result, the highest accuracy of classification is 82.86% with the best classification time point 4.09 sec, maximum mutual information (MI) 0.47 bit and maximum MI steepness 0.431 bit/s. Compared to the results of BCI 2003 competition, the method as above can provide greatly improved maximum MI steepness, thus verifying that the method is more adaptable to what are required by the online BCI system. References | Related Articles | Metrics

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Improving ElGamal digital signature algorithm by adding a random number Li, Xiao-Feng (1); Zhao, Hai (1); Wang, Jia-Liang (1); Bi, Yuan-Guo (1) 2010, 31 (8):  1102-1104+1112.  DOI: - Abstract ( 331 )   HTML   PDF (260KB) ( 953 )   To solve the security problem of the ElGamal digital signature scheme which requires only one random number, an improved program is proposed by adding a random number to it so as to make the decryption more difficult. The security of the improved signature scheme is still based on the computation difficulty of discrete logarithm over finite domain. Then, how to enhance the complexity between the random number and the key due to adding a random number is discussed, as well as the security and time complexity of the improved signature scheme. The results show that the security of the improved signature scheme is enhanced with the time complexity increased little, in comparison with the original signature scheme. References | Related Articles | Metrics

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On the formation of P-rich surface layer of twin-roll cast high-P strip Qiu, Yi-Qing (1); Zhou, Guo-Ping (1); Liu, Zhen-Yu (1); Wang, Guo-Dong (1) 2010, 31 (8):  1105-1107.  DOI: - Abstract ( 245 )   HTML   PDF (809KB) ( 557 )   To take further the advantage of the solute-rich surface layer of twin-roll cast high-P steel strip, the causes for the formation of the P-rich surface layer were discussed. Experimental results indicated that there will be a P-rich layer nearby the surface of the higher-P strip after controlling the processing parameters, but the distribution of phosphorus is basically uniform in the lower-P strip under the same conditions. Theoretical analysis showed that the rolling force may drive the interdendritic P-rich liquid metal back onto the strip surface, thus resulting in the formation of the P-rich layer in the strip under the preconditions that the kiss point takes place above the bite and the cross-section temperature of the nearby region below the kiss point is between the liquidus and solidus temperature. References | Related Articles | Metrics

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Development of software for online control of plate reheating in heat-treatment process Li, Jia-Dong (1); Li, Yong (1); Wang, Zhao-Dong (1); Wang, Guo-Dong (1) 2010, 31 (8):  1108-1112.  DOI: - Abstract ( 186 )   HTML   PDF (1186KB) ( 523 )   An online control software was developed by Visual C++6.0, WinCC 6.2 of Siemens, SQL Server 2005, etc., for the new heat-treatment system of alloy plate/strip hot-rolling line in Baosteel. Mainly the software comprises a man-machine interface, process computation model, communication softwares and real-time data management system. The modeling principle is described in detail. The online running results of the software developed showed that combining the plate-reheating system with basic automation is able to not only reduce the operation complexity but also greatly increase the precision of temperature control and quality of plates in the heating process. References | Related Articles | Metrics

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Fast 1.5-dimension rigid-plastic FEM solution to strip rolling process Mei, Rui-Bin (1); Li, Chang-Sheng (2); Liu, Xiang-Hua (2); Bao, Li (1) 2010, 31 (8):  1113-1116+1125.  DOI: - Abstract ( 229 )   HTML   PDF (1846KB) ( 576 )   To improve the FEM computational efficiency and implement its online application, an 1.5-dimension rigid-plastic FEM (RPFEM) model was developed as the fast solution to the strip rolling process, where the shape function and the B and Hessian matrixes of 1.5-dimension RPFEM were derived to decrease the number of unknown values and degrees of freedom. The different strip rolling processes were solved successfully by the software RF-1.5D we developed, and the rolling force, iteration steps and computing time were investigated with the data acquired from a certain plant. The calculated value of rolling force is basically in agreement with the measured value, i.e., an error less than 10%. The iteration steps in the solution for a single pass rolling are thus less than 35 and take 100 ms only, which means that the computing time for every iteration step is shortened by 1.5-dimension RPFEM in comparison with that by 2D. The precision and high efficiency of the 1.5-dimension RPFEM are therefore proved available to meet the basic requirements for online prediction. References | Related Articles | Metrics

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Experimental research on rolling-lubricating process on 4-high reversing cold rolling mill Li, Chang-Sheng (1); Li, You-Yuan (2); Yu, Tao (1); Cui, Guang-Zhu (1) 2010, 31 (8):  1117-1120.  DOI: - Abstract ( 382 )   HTML   PDF (956KB) ( 769 )   The experiments of lubrication process with the emulsions A, B, C and D as lubricating oil for the St12 strip rolling on a 4-high reversing cold mill were carried out. The effects of the four emulsions on the rolling force, strip surface reflectivity, surface temperature of strip rolls under the same rolling conditions were analyzed comparatively, as well as the relationship between rolling force and rolling speed. Moreover, the friction coefficient was calculated with the measured data of rolling force by a mathematical model. It was revealed that the sequences of the emulsions from first to last in relation to the lubrication quality, cooling performance and strip surface reflectivity are B-C-D-A, A-C-D-B and B-D-C-A, respectively. The experimental results are of theoretical and practical importance to the development and evaluation of rolling oil, optimization of rolling-lubricating process parameters and improvement of strip steel surface quality. References | Related Articles | Metrics

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Preparation of MgO nanofilm on surface of 3D-SiC by sol-gel method Yu, Liang (1); Ma, Ya-Na (1); Ru, Hong-Qiang (1); Yue, Xin-Yan (1) 2010, 31 (8):  1121-1125.  DOI: - Abstract ( 542 )   HTML   PDF (1745KB) ( 924 )   With Mg(NO3)2·6H2O, anhydrous ethanol and collodion emulsion used as starting materials, solvent and surfactant, respectively, the MgO sol was prepared by sol-gel method. Then the MgO sol was coated on the surface of the ceramic skeleton of 3D-SiC by dip-coating process to get MgO nanofilm after roasting. The phase composition and microstructure of the nanofilm were investigated via XRD and SEM. The results showed that the smooth and compact MgO nanofilm whose thickness ranges from 0.8 to 1.0 μm can be deposited on the surface of 3D-SiC as substrate the way the substrate should be eroded in HF solution for 30 min to make sure that the coated MgO sol has the mass ratio of Mg(NO3)2·6H2O to collodion emulsion is equal to 1.0, then it is dried at 80°C for 10 min and, later on, at 480°C for 10min and roasted at 800°C for 1 hr. The MgO nanofilm is bonded well to the substrate, and its average particle size is about 500 nm. References | Related Articles | Metrics

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Water modeling study on circulating flowrate and mixing characteristics in RH-PTB process Geng, Dian-Qiao (1); Lei, Hong (1); Zhang, Xing-Wu (1); He, Ji-Cheng (1) 2010, 31 (8):  1126-1128+1140.  DOI: - Abstract ( 222 )   HTML   PDF (425KB) ( 551 )   To have an insight into the circulating flowrate and mixing characteristics in RH-PTB vacuum refining process, the relevant system was modeled on a scale of 1:5.5 to investigate the effects of different parameters on the circulating flowrate and mixing time. The results showed that with the increasing bubbles' travel and the liquid level in vacuum chamber and decreasing quantity of liquid steel for refining, the circulating flowrate increases while the mixing time decreases. So, some effective measures should be taken in actual system to increase the circulating flowrate in case the quantity of liquid steel for refining is overmuch for refining. Besides, the expressions of circulating flowrate and mixing time were derived by regression equation with experimental data. References | Related Articles | Metrics

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Study on critical velocity of slag entrapment in ladle furnace under linear electromagnetic stirring Su, Zhi-Jian (1); Li, Yan-Hua (1); He, Ji-Cheng (1) 2010, 31 (8):  1129-1132.  DOI: - Abstract ( 245 )   HTML   PDF (418KB) ( 591 )   A nearby electromagnetic stirring system was provided for a ladle refining furnace, where the velocity distribution of liquid metal on the interface between simulated slag and liquid metal was measured and analyzed with Doppler ultrasonic velocimetry so as to determine the important metallurgical parameters such as the critical velocity of slag entrapment in furnace, as well as the relevant parameters of actual ladle furnace. The results showed that the electromagnetic stirring can effectively enhance the internal flow of liquid metal so as to improve its internal kinetic conditions significantly. The electromagnetic stirring is therefore an efficient means to improve the efficiency of ladle refining. Different electromagnetic stirring intensity should be introduced to meet different refining process requirements for commercial production in accordance to the determined critical velocity of slag entrapment. References | Related Articles | Metrics

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Optimized water-consumption network in iron and steel complex and its evaluation index system Gao, Cheng-Kang (1); Dong, Hui (1); Cai, Jiu-Ju (1); Yu, Zhi-Qiang (1) 2010, 31 (8):  1133-1136.  DOI: - Abstract ( 327 )   HTML   PDF (1192KB) ( 635 )   Integrating all the water-consumption processes and the whole production process of an iron and steel complex into a water-consumption network system, then the model of the system was developed with its evaluation index system given via the following-observing model of SFA (substance flow analysis). An iron and steel complex in China was taken as an example to which a water-consumption network model was developed to find out the problems in water-consumption system, thus analyzing its optimization and evaluation. The results revealed that the system has even more water-saving potential in such processes as coking, continuous casting and rolling with a high potentiality of water-environment efficiency as an evaluation index and remarkable water-saving achievement due to optimization. All of these showed that the SFA following-observing model is available to theoretically optimize the water-consumption network in an iron and steel complex. References | Related Articles | Metrics

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Effects of alumina as dopant on sintering and grain growth behavior of 9 mol% yttria-stabilized zirconia Liu, Tao (1); Li, Lin (2); Yu, Jing-Kun (1); Xu, Ji-Lin (1) 2010, 31 (8):  1137-1140.  DOI: - Abstract ( 273 )   HTML   PDF (437KB) ( 706 )   Al2O3-doped 9 mol% yttria-stabilized zirconia (9YSZ) was synthesized by the chemical co-precipitation of hydroxides. The solid solubility of Al2O3 as dopant in 9YSZ was characterized by XRD, with the lattice parameters calculated. Then, the effects of Al2O3 on sintering and grain growth behavior of 9YSZ was investigated. The result showed that the lattice parameter of YSZ decreases from 0.51408 nm to 0.51351 nm when the doped Al2O3 is increased up to 0.48wt%, but the lattice parameter remains unchanged if the Al2O3 is doped further. It means that the limit of solid solubility of Al2O3 in 9YSZ is about 0.48wt% and that the Al2O3 as dopant can accelerate the sintering process so as to hurry up the grain growth and make 9YSZ denser. References | Related Articles | Metrics

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On the slag weight loss during roasting for electroslag remelting Dong, Yan-Wu (1); Jiang, Zhou-Hua (1); Xiao, Zhi-Xin (1); Li, Zheng-Bang (2) 2010, 31 (8):  1141-1144.  DOI: - Abstract ( 333 )   HTML   PDF (796KB) ( 751 )   The slag weight loss during roasting for electroslag remelting was investigated in laboratory via thermogravimetry. The relationship between roasting temperature and the content of hydratable components in slag was studied, especially the relationship between slag bed thickness and roasting time and that between roasting temperature and time under zero-gravity conditions, with several equations given by numerical fitting. The experimental results were analyzed through solid-phase thermal decomposition mechanism and indicated that in the earlier stage the thermal decomposition is dominated by nucleation and growth of crystal nucleus, and in the later stage it mainly depends on the diffusion controlled reaction. Such results will provide the directions to the roasting process of slag. References | Related Articles | Metrics

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Refining effect/mechanism of CaCO3 in AZ31 magnesium alloy Gao, Sheng-Yuan (1); Zhang, Zhi-Qiang (1); Le, Qi-Chi (1); Cui, Jian-Zhong (1) 2010, 31 (8):  1145-1148.  DOI: - Abstract ( 234 )   HTML   PDF (1490KB) ( 653 )   Taking CaCO3 as a refining agent, the influence of CaCO3 on the microstructure of AZ31 magnesium alloy was investigated. The results showed that the best refining effect is obtained if adding 0.5wt% CaCO3 to the alloy at 760°C held for 10 min, i.e., the average grain size of α-Mg decreases to 209 μm from about 570 μm of the alloy or 63.3% is reduced. Based on the analysis of EDS, the calculations of binding energy and Gibbs free energy proved that, the grain refining mechanism is resulting from a part of Al4C3 particles as heterogeneous cores generated after the reaction of CaCO3, whereas the rest of Al4C3 particles are pinned to the grain boundary to retard the grain growth, and Al element is then quickly pushed to the grain boundary along the solid-liquid interface to generate the β-Mg17Al12 phase growing along the grain boundary, thus immobilizing the grain boundaries with the distributions of alloying elements changed. References | Related Articles | Metrics

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Study on Al-electrodeposition from TMPAC-AlCl3 ionic liquids Liu, Quan (1); Liu, Kui-Ren (1); Han, Qing (1); Tu, Gan-Feng (1) 2010, 31 (8):  1149-1152.  DOI: - Abstract ( 278 )   HTML   PDF (1165KB) ( 1117 )   Al plating was electrodeposited on cupronickel alloy as substrate in the trimethyl-phenyl-ammonium chloride and anhydrous aluminum chloride (TMPAC-AlCl3) quaternary ammonium room temperature ionic liquids with benzene used as solubilizing assistant. The effects of current density and plating time on surface microscopic morphology and cathodic current efficiency were studied. The corrosion resistance of the as-deposited Al layer was evaluated by potentiodynamic polarization measurements. Moreover, scanning electron microscope, energy dispersion X-ray spectrometer and X-ray diffraction were used to characterize the samples. The results showed that the as-deposited Al plating obtained at 15 mA/cm2 for 30 min has a compact surface. Its cathodic current efficiency exhibits a maximum value up to 92% and decreases with increasing plating time mainly because of the precipitation of AlCl3 on the surface of Al anode. The polarization measurements showed that the thicker the Al plating, the higher the corrosion resistance of the plating. Moreover, the anodic passivation behavior of the as-deposited Al plating (17 μm thick) was found, which can effectively protect the substrate from corrosion. References | Related Articles | Metrics

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Effect of amorphous carbon-doping on microstructure and superconductivity of MgB2 wires Sun, Yu-Yan (1); Zhang, Ping-Xiang (1); Bai, Zhi-Ming (2); Chen, Si-Hua (2) 2010, 31 (8):  1153-1156.  DOI: - Abstract ( 240 )   HTML   PDF (1363KB) ( 621 )   The amorphous carbon-doped MgB2-xCx/Nb/Cu single-core wires were prepared by in-situ PIT(powder in tube) method, where the C-doping content x=0, 0.05, 0.10 and 0.15. Phase formation and microstructure of the wire samples with different doping contents were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), and so on. It was found that the C content entering into MgB2 lattice increases with increasing carbon doping content, while the interlayer structure of MgB2 changes little. Electric properties of the samples showed that they meet the practical requirements of superconducting magnet, i.e., the critical current density of samples is 8.1×104, 1.7×105, 1.6×105 and 1.0×105 A/cm2 at 30 K in the 0.2 T external electromagnetic field when the C-doping content x=0, 0.05, 0.10 and 0.15, respectively. As shown by the experimental results, the optimum C-doing content x ranges from 0.05 to 0.1. References | Related Articles | Metrics

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Preparation of BaO-Fe2O3-SiO2 glass-ceramics from iron ore tailings and microwave dielectric properties Xue, Xiang-Xin (1); Yu, Hong-Hao (1); Huang, Da-Wei (1) 2010, 31 (8):  1157-1160.  DOI: - Abstract ( 277 )   HTML   PDF (1419KB) ( 472 )   BaO-Fe2O3-SiO2 glass-ceramics were prepared with the iron ore tailings in ANSTEEL as starting material. The crystallization process, kinetics and microstructure of the glass-ceramic were investigated by DSC, XRD, SEM and FT-IR. The optimal heat-treatment schedule showed that the nucleation temperature is 700°C held for 2 h with the crystallization temperature 950°C held for 3 h and, as a result, the main and minor crystalline phases of the glass-ceramic are BaFe12O19 and BaSi2O5, respectively. The IR characteristic absorption peaks corresponding to BaFe12O19 were observed in the glass structure. The index of crystal growth is 2.8, which implies that crystals grow along three dimensional spaces. Moreover, the dielectric loss tangent is up to 0.44 while the magnetic loss tangent is only 0.017, which means that the glass-ceramic thus prepared is good at microwave dielectric properties. References | Related Articles | Metrics

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Synthesis of fertilizer from titanium-bearing blast furnace slag Zhang, Yue (1); Yang, He (1); Wang, Li (1); Xue, Xiang-Xin (1) 2010, 31 (8):  1161-1164+1169.  DOI: - Abstract ( 610 )   HTML   PDF (1181KB) ( 885 )   With titanium-bearing blast furnace slag and (NH4)2SO4 as raw materials, a compound fertilizer was synthesized by heating to enhance its solubility and transforming nutritional elements into the other form available to be absorbed easily by plants. The effects of process conditions on the dissolving rate of fertilizer were investigated, and the results showed that the appropriate process conditions for the fertilizer are the mass ratio of (NH4)2SO4 to water-quenched slag is 8:1 with the reaction temperature 320°C held for 36 min. Thus, the dissolving rates of titanium, magnesium and iron in the slag are 84%, 88% and 75%, respectively. The fertilizer contains such nutritional elements as nitrogen, silicon, sulfur, calcium, magnesium, iron and titanium, which can all be absorbed to nurture plants effectively. Among them, the elements nitrogen, iron, titanium, magnesium and most of sulfur are in the form of water-soluble substances which can be used as the quick-released components. References | Related Articles | Metrics

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Thermodynamical and technological studies on in-situ self-generating Ti(C, N) ceramic coating via laser cladding Yang, Yu-Ling (1); Yao, Wen-Ming (1); Liu, Jun-Bin (2); Zhang, He-Zhi (1) 2010, 31 (8):  1165-1169.  DOI: - Abstract ( 312 )   HTML   PDF (1223KB) ( 719 )   The in-situ self-generating Ti(C, N) ceramic coating prepared on the surface of Ti-6Al-4V alloy by laser cladding (LC) deposition was investigated, where a 500 W pulsed YAG laser was used as radiation source with the 99%-purity N2 used for nitrogenation and the titanium powder (particle size 20 μm) mixed with powdered graphite used as the precursor. The effects of the in-situ self-generating reaction mechanism and such process parameters as pulse width, pulse frequency and scanning speed on the coating were studied by thermodynamic analysis in combination with XRD. XRD results showed that the main phases of the coating are TiC0.3N0.7 and TiN or TiN0.3, and that the appropriate process parameters include the pulse frequency 15 Hz, pulse width around 3.0 ms, scanning speed in the range from 2.0 to 4.0 mm/s, N2 pressure 0.4 MPa and defocus distance 15 mm. The metallographic results showed that the dendrite structure is dominant in the coating and distributed quite uniformly, and that the ceramic coating is bonded well to the substrate. References | Related Articles | Metrics

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Dynamic simulation of forging manipulator based on virtual prototyping Ren, Yun-Peng (1); Han, Qing-Kai (1); Zhang, Tian-Xia (1); Wen, Bang-Chun (1) 2010, 31 (8):  1170-1173+1186.  DOI: - Abstract ( 253 )   HTML   PDF (707KB) ( 675 )   Based on the working principle of a forging manipulator, a 3-D model of the simplified forging manipulator was developed with the software Solidworks, which was then introduced into the MSC.ADAMS software system to set up a 3-D digital prototype. Considering the effects of dead weight and loading on the manipulator, some constraints and loads were applied to all the components of the forging manipulator model. Thus, a visual 3-D dynamic simulation of multi-rigid-body system was done to analyze the loading conditions for the hydraulic cylinders and jaw of the forging manipulator during typical operation, as well as the limit loading conditions. Besides, the simulated results provided the reasonable reference for the design of components of a forging manipulator. References | Related Articles | Metrics

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Anthropomorphic manipulation of excavator based on Fuzzy Logic/Stateflow Yang, Ke-Shi (1); Liu, Jie (1); Gu, Yu-Ming (1) 2010, 31 (8):  1174-1177.  DOI: - Abstract ( 348 )   HTML   PDF (249KB) ( 644 )   To improve the autonomous operation of excavator's attachment and reduce the intensity of operator's labor, an I-FORMA-O approach was presented for the behavioral control of the princpal actions of a PC02 excavator to be implemented and for developing a simulating model based on Fuzzy Logic/Stateflow. The Simulink experiments verified that the state-transition process of excavating behavior is resulting from the events which were driven by the correspoding principal actions. And the result showed that the principal actions defined by Fuzzy Logic simplifies the computation and that the model as a platform is visual, reliable and available to resort to drivers' operating experience for the excavator or modify it so as to improve the R and D efficiency. Thus, a foundation is laid to directly generate an executable code for the applications of RTW (real-time workshp) tool kit. References | Related Articles | Metrics

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Aerodynamic analysis of horizontal-axis pitch-variable wind turbine Wang, Xiao-Dong (1); Yan, Fang (1) 2010, 31 (8):  1178-1181.  DOI: - Abstract ( 248 )   HTML   PDF (1158KB) ( 619 )   A mathematic model based on free trailing vortex theory and lifting-surface theory was developed to describe the ambient airflow by blades and characteristics of wind turbine so as to investigate the aerodynamic behavior of a wind turbine blade. A numerical solution to the model was carried out to obtain the relationship between tip velocity ratio and power coefficient as well as that between wind velocity and power coefficient by introducing the induced velocity between the blades and vortices. Compared with experimental data, it was found that the theoretical results conform basically with the experimental results. Further, compared with the CFD (computational fluid dynamics) method, the free trailing vortex method would get acceptable computational accuracy at lower cost. The results are therefore regarded as available to select the wind turbine position in a wind field and optimize the design of wind turbine control system. References | Related Articles | Metrics

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Acoustic emission monitoring for failure process of Brazilian disc samples Zhao, Xing-Dong (1); Yang, Su-Jun (1); Xu, Shi-Da (1); Liu, Jian-Po (1) 2010, 31 (8):  1182-1186.  DOI: - Abstract ( 291 )   HTML   PDF (1273KB) ( 696 )   The acoustic emission (AE) and Geiger location algorithm were used to experimentally investigate failure process of different Brazilian disc samples under loading conditions. The results showed that AE events are mainly resulting from the propagation of crack. In the period beginning with loading up to crack initiating the AE activities are unobvious, but the AE events increase obviously once the initial crack occurs at the relevant stress monitoring point. Then, the microcracks are propagated unstably more and more, until finally the rock fails, and in such a period the AE activities increase unusually, i.e., AE events come up to its highest rate of change. Therefore, the experiments visually showed the occurrence of initial crack in samples and propagating space/orientation. For most of the samples failure begins from a loading position, and for the rest the initial crack occurs within the samples. Moreover, the location of AE events reflects the macro-evolution of the interior stress field, which is of significance to the investigation on the destabilization mechanism of rock failure. References | Related Articles | Metrics

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Development and application of high-intensity permanent magnetic separator for pre-concentration Yuan, Zhi-Tao (1); Gao, Tai (1); Guo, Xiao-Fei (1); Han, Yue-Xin (1) 2010, 31 (8):  1187-1191.  DOI: - Abstract ( 207 )   HTML   PDF (1389KB) ( 585 )   A high-intensity permanent magnetic separator for pre-concentration was designed and developed with the new-type extruded permanent magnet made of Nd-Fe-B. Then, the magnetic induction on the surface of belt conveyor came up to 1.0 T with the maximum magnetic gradient up to 68 mT/mm. Pre-concentration tests were done for the extra-lean hematite from Qidashan Iron Mine, including the size fractions -75 mm+50 mm, -50 mm+20 mm, -20 mm+5 mm, -5 mm+0 mm-roughing and scavenging each once. After the pre-concentration, the Fe ore grade was improved by 5.3%~6.8% if the original grade was 17%~18%, i.e., the recovery rate is higher than 60% and tailing grade around 13% with the yield of tailing higher than 50%. References | Related Articles | Metrics

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Preparation of MgO with different nanoparticle sizes and their infrared wave absorptivities Liu, Guo-Liang (1); Zhu, Yi-Min (2); Fang, Xin (2); Zhang, Wei-Jia (2) 2010, 31 (8):  1192-1195.  DOI: - Abstract ( 397 )   HTML   PDF (789KB) ( 1597 )   MgO with different nanoparticle sizes were prepared and their samples were characterized by XRD and IR spectroscopy to investigate their infrared wave absorptivities. IR spectroscopic results indicated that the absorption peak widens in the range from 400 to 600 cm-1 and the IR wave absorptivity is improved evidently, where red shift and blue shift coexist. The blue shift is found with the decreasing particle size, then the red shift is found when an inflection point takes place in the vicinity that the particle size is around 50 nm. The crystalline field effect often results in the widened absorption peak because of the "surface atomic effect" of nanocrystals. The decreasing nanoparticle size may lead the fine structure of the spectral band of conventional lump materials to disappear, thus forming a wide and flat absorption band. References | Related Articles | Metrics

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Preparation of bacterial cellulose and its adsorption of Cd2+ Lu, Min (1); Li, Yan-Ying (2); Guan, Xiao-Hui (2); Wei, De-Zhou (1) 2010, 31 (8):  1196-1199.  DOI: - Abstract ( 346 )   HTML   PDF (380KB) ( 976 )   Taking the Gluconacetobacter xylinus Gyll as strain, the fermentation conditions for the preparation of bacterial cellulose was optimized by L18(37) orthogonal test, and the bacterial cellulose thus prepared was used for the adsorption of Cd2+. Then, the effects of such performance parameters as pH value and adsorbing time on the efficiency of adsorption were investigated, with the adsorption kinetics and adsorption isotherms simulated. The results showed that the optimal ferment conditions for preparing bacterial cellulose are as follows: corn steep powder 5%, sucrose 6%, the initial medium pH value 6.0, fermentation broth inoculum 12%, the second species of seed age for enlargement cultivation 22 hr and static culture period 7 days. The highest yield of bacterial cellulose is 12.36 g/L. In the process with bacterial cellulose as sorbent for removing Cd2+, the pH value is a very important parameter to the adsorption efficiency. The adsorption rate could be well fitted by pseudo-second rate model, and the adsorption isotherm could be described by Langmuir model, both having good linearity. All these facts verify that the bacterial cellulose provides a typical monomolecular-layer adsorption of Cd2+. References | Related Articles | Metrics

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Calculation of bearing capacity of eccentrically loaded GFRP tube columns filled with steel reinforced concrete Qin, Guo-Peng (1); Wang, Lian-Guang (1); Liu, Mei-Si (2) 2010, 31 (8):  1200-1203.  DOI: - Abstract ( 279 )   HTML   PDF (1196KB) ( 571 )   GFRP tube filled with steel reinforced concrete column consists of an outer tube made from glass fiber reinforced polymer (GFRP), steel reinforcement and inside core concrete. Tests were conducted with five specimens to study their bearing capacity under eccentrical load via a nonlinear analysis program based on the fiber model. The effects of strength of concrete, slenderness ratio, eccentricity and percentage of reinforcement on the mechanical properties of the eccentrically loaded columns were analyzed, with the relevant load-deflection relationship calculated. The results indicated that the bearing capacity of such composite members increases with the core concrete strength and percentage of reinforcement but decreases with the increasing slenderness ratio and eccentricity. Based on the analysis of calculated results, the formulae are given to predict the bearing capacity of the composite columns subjected to eccentric compression, which conform well with experimental results. References | Related Articles | Metrics

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Credit relation between bank and enterprise under information asymmetry Zhang, Yan-Bing (1); Liu, Jian-Bo (2); Zhang, Yan-Yan (2) 2010, 31 (8):  1204-1207.  DOI: - Abstract ( 273 )   HTML   PDF (142KB) ( 591 )   According to the commercial integrity that plays an important role in the cooperation between bank and enterprise, the credit relation between them is studied on the basis of the principal-agent theory and centipede game theory, etc., and the credit process is divided into two stages, i.e., one-time game and repeated game. In the one-time game the phenomenon of reluctance to loan is explained, and in the repeated game the optimal cycle of cooperation is determined, as well as the minimum expected credit rationing of the enterprise applying for loan. Such a mechanism will avoid the adverse selection and reduce the moral risk in the credit process to a certain degree. References | Related Articles | Metrics

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Improvement and application of SERVQUAL service quality measurement method Xu, Xian-Ying (1); Ma, Qin-Hai (1) 2010, 31 (8):  1208-1212.  DOI: - Abstract ( 407 )   HTML   PDF (1723KB) ( 1753 )   Some problems were found in the applications of SERVQUAL, such as the fuzziness of prospective target in the expected measurement which is unavailable to completely express what idea is expected, nonsense of gap computing and inappropriate model structure. A modified measurement model M-SERVQUAL was therefore developed instead of SERVQUAL to compute the gap between expectation and perception via the modified gap formula, i.e., (service perceived)-(target value)×(self-confidence level). Then, the different quality dimensionalities were combined with the service quality perceived in the model structure, where all the dimensionalities were measured in terms of response indices. A comparison between SERVQUAL and M-SERVQUAL was made empirically via structural equation, based on the data from the Shenyang International Horticultural EXPO 2006. The results showed that the M-SERVQUAL model has higher reliability, validity and goodness of fit. The M-SERVQUAL model was used to analyze the resource allocation and choice of marketing strategies in management. References | Related Articles | Metrics

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Dynamic behavior of exchange-biased vortex in permalloy nanodisk Liu, Yan (1); Hu, Yong (1); Du, An (1); Chao, Yue-Sheng (1) 2010, 31 (8):  1213-1216.  DOI: - Abstract ( 213 )   HTML   PDF (1104KB) ( 712 )   The dynamic behavior of the exchanged-biased vortex in permalloy nanodisk was studied by numerical calculations based on the interfacial exchange model we developed. It was found that the frequency of the gyrotropic motion of the vortex core increases linearly with the increasing interfacial exchange constant between ferromagnetic and antiferromagnetic layers under the action of the vortex-shaped pinning field. Meanwhile, the relaxation time required from the vortex core to equilibrium position shortens, thus providing a damping effect on the motion of the vortex core. Then, the trajectory of the vortex core in ferromagnetic layer is no longer a simple helix due to the exchange bias under the action of an external magnetic field, and the distance between vortex core and disk center increases in fluctuation until a stable value happens. References | Related Articles | Metrics