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15 April 2006, Volume 27 Issue 4 Previous Issue    Next Issue
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Reliable placement of disk pole against sensor failures Yao, Bo (1); Sun, Xin (2); Zhang, Qing-Ling (2); Zhang, Si-Ying (1) 2006, 27 (4):  355-358.  DOI: - Abstract ( 241 )   HTML   PDF (185KB) ( 484 )   The reliable design of disk pole placement against sensor failure is investigated for linear systems. A continuous model of sensor actuator failure is presented, which is more practical and general than discrete models. A sufficient condition is given to control the reliable pole placement in a definite disk. Dynamic output feedback controller is thus designed by solving LMI (linear matrix inequality). A simulation example shows the effectiveness and necessity of such a reliable placement. References | Related Articles | Metrics

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Decentralized robust control for a class of generalized nonlinearly-intercorrelated large-scale systems with uncertainties Ma, Yue-Chao (1); Zhang, Qing-Ling (1); Tong, Song (1) 2006, 27 (4):  359-362.  DOI: - Abstract ( 242 )   HTML   PDF (248KB) ( 553 )   A class of generalized nonlinearly-intercorrelated large-scale systems with uncertainties and similar structures is considered, of which the decentralized stabilization is studied by virtue of Lyapunov stability theory, matrix theory and decomposing process of a generalized large-scale system. The condition of stabilization is given for the systems by using Lyapunov equation method and matrix norm properties, and a decentralized robust stabilization controller is designed. Meanwhile, the bounds of uncertainties of the generalized nonlinearly-intercorrelated large-scale systems are determined, as well as those of all the individual subsystems which are stabilized asymptotically at the same time. References | Related Articles | Metrics

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Modeling and simulation of influence of temperature on batch fermentation process of nosiheptide Zhang, Da-Peng (1); Wang, Fu-Li (1); He, Jian-Yong (2); He, Da-Kuo (1) 2006, 27 (4):  363-366.  DOI: - Abstract ( 224 )   HTML   PDF (1267KB) ( 483 )   How the temperature affects the batch fermentation process of Nosiheptide was investigated via modeling and simulation. Where its direct influence on biomass growth rate is expressed by Arrennius equation and that on product yield is given by fitting experimental values. The indirect influence of temperature on dissolved oxygen was investigated via modeling in relation to the ingredients of medium. Then, the model of batch fermentation process of Nosiheptide at constant temperature/pressure was improved, and it was further verified via an experiment done in a 100 L fermenter. It is shown that the improved model conforms well to experimental results. A simulation test based on the improved model was thus conducted and the results showed exponentially that in the range from 26°C to 32°C the biomass growth rate increases with temperature but, eventually, the biomass concentration almost remains unchanged no matter how high/low the temperature is. In stationary phase however the mean biomass concentration changes slightly with changing temperature. The maximum product yield is found at 28°C, which will decrease if the temperature is too high or low. References | Related Articles | Metrics

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Globally exponential stability of cellular neural networks with multiple time-varying delays Wang, Zhan-Shan (1); Zhang, Hua-Guang (1) 2006, 27 (4):  367-370.  DOI: - Abstract ( 213 )   HTML   PDF (316KB) ( 574 )   Globally exponential stability of a class of cellular neural networks with multiple time varying delays is investigated. Using the technique by virtue of Young and Halanay inequalities, some new sufficient criteria are given to ensure the uniqueness of equilibrium point and globally exponential stability. In this way the criteria given for globally exponential stability are entirely independent of time delay without the differentiability of time-varying delay and the strict monotonicity of neuron's excitation function. In addition, some remarks are given to explain how the results as shown in this paper improves and extends the earlier works as references of which the effectiveness is proved via simulation example. References | Related Articles | Metrics

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Way to compensate temperature for high-precision electronic balance Zhou, Wei (1); Zhang, Shu-Hong (1); Zhang, Ze (1); Zhang, Zhi (2) 2006, 27 (4):  371-374.  DOI: - Abstract ( 248 )   HTML   PDF (759KB) ( 578 )   The circuit structure of a bidirectionally forced electronic balance is unsuitable for temperature compensation if using hardwares. An attempt is therefore made to apply the neural network to the balance for temperature compensation. It is found that the drift of mass indicating values changes nonlinearly if placing the balance in a full temperature field where the mass remains unchanged. On the other hand, the drift changes linearly if placing the balance in a full mass field where the temperature remains unchanged. Based on the two important characteristics, the neural network is applied to the balance for temperature compensation. The result indicates that the new way to compensate temperature is highly practical and precise to improve effectively the metering accuracy of electronic balance. References | Related Articles | Metrics

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Model of head sag of round bars in rolling process Hao, Pei-Feng (1); Liu, Ye (2); Chen, Lin (3); Tang, Jin-Song (3) 2006, 27 (4):  375-377.  DOI: - Abstract ( 213 )   HTML   PDF (197KB) ( 578 )   The head sag of a minimum-size round bar in rolling process was investigated to prevent it from crooking and heaping in front of a flying shear. The temperature of bar, rolling force and power of mill drive motor were thus modeled to analyze the causes of bar crooking/heaping, such as the decreasing internal stress due to reduced bar size enables the head of running bar to be lower than the baffle of flying shear, crook and heap. Solving the function of deflection of round bar, a mathematic model was developed for its head sag. Some in-situ rolling experiments were conducted for various small-size round bars to check how the theoretically calculated results conform to the actuality. They showed that the calculated results in accordance to the head sag model are in conformity to experimental results in case there is or no flying shear. References | Related Articles | Metrics

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Mobile IP buffer scheme based on dynamical hierarchical gateway agent Xue, Jian-Sheng (1); Wang, Guang-Xing (1) 2006, 27 (4):  378-381.  DOI: - Abstract ( 236 )   HTML   PDF (245KB) ( 521 )   Discusses the buffer scheme in the process of smooth handoff in mobile IP. A dynamical model of hierarchical gateway agent is proposed to analyze the buffer process, as well as the distribution and management of buffer area. A simulating test is thus carried out. The result and theoretical analysis reveal that dividing the buffer area into two levels, i.e., gateway agent area and local agent area which forms dynamically, will decentralize the buffer mission. Then, introduces a single buffer in combination with cross link list and corresponding strategy for release and proper setup into the scheme to solve effectively such problems as data loss when handing off mobile nodes, TCP performance degradation and disorderly data. The scheme also provides a foundation on which the smooth handoff in mobile IP can further be investigated. References | Related Articles | Metrics

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Modified MMSE multiuser detection algorithm based on SP subspace tracking Wang, Jin-Kuan (1); Jia, Li-Qin (1); Liu, Zhi-Gang (1); Xue, Gui-Qin (1) 2006, 27 (4):  382-385.  DOI: - Abstract ( 247 )   HTML   PDF (992KB) ( 572 )   Several algorithms of subspace tracking are analyzed. Eigenvalue decomposition and singular value decomposition with high computation complexity are not adaptable to engineering practice, while the multiuser detection implemented by PASTd with less computation complexity provides low convergence rate and detectability. Introduces the SP algorithm and utilizes it to track the signal subspace so as to obtain a demodulating vector. A modified MMSE detector was thus designed. To compare it with the performance of PASTd MUD and SP MUD, a simulation test was conducted and the results showed that the SP MUD algorithm with less computation complexity has faster convergence rate and provides the output SINR/bit error rate (BER) similar to SVD MUD. References | Related Articles | Metrics

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Multi-mode antenna selection algorithm with partial channel-state information Wang, Jin-Kuan (1); Xue, Gui-Qin (1); Liu, Zhi-Gang (1); Tian, Dan (1) 2006, 27 (4):  386-389.  DOI: - Abstract ( 278 )   HTML   PDF (1073KB) ( 693 )   Analyzes the necessity to select antenna with partial channel-state information, and investigates the effects of angular spread, signal to noise ratio (SNR) and antenna configuration at transmitter on the capacity of MIMO system with correlated channel taken into account. A multi-mode antenna selection algorithm is proposed in which the number of active transmitters is determined dynamically according to the channel state, thus determining the amount of feedback information. Then, feedback vectors are used for beamforming at transmitting antenna so as to select some subchannels with higher gain for data transmission. Compared with a system using all available antennae, the simulation results showed that the system with antenna selection can reduce the complexity of system configuration and minimize the cost. Furthermore, the algorithm will keep applicable even if channels are strongly correlated. References | Related Articles | Metrics

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Theoretical and simulating analysis of UC-MUSIC algorithm Liu, Zhi-Gang (1); Wang, Jin-Kuan (1); Wang, Fu-Li (1); Zhao, Hong-Tao (1) 2006, 27 (4):  390-393.  DOI: - Abstract ( 241 )   HTML   PDF (166KB) ( 465 )   A signal-selective unitary cyclic MUSIC algorithm or UC-MUSIC is proposed to estimate the direction of arrival of signals in multipath environment. Reconstructing the data model in terms of cyclic self-correlation matrix, the algorithm becomes Hermitian and thus provides a good solution to the problem of propagation of highly-correlated signals in a multipath environment via real-valued decomposition to simplify computation. The derivation of mean square error(MSE) shows that this algorithm is adaptable to not only the uncorrelated but also the highly-correlated or coherent signals. In addition, simulation results showed that this algorithm is available to multipath environment and has better performance with lower computational complexity in comparison with the cyclic MUSIC algorithm. References | Related Articles | Metrics

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Realization mechanism and performance of WebitOS kernel Zhang, Xi-Yuan (1); Zhao, Hai (1); Sun, Pei-Gang (1); Luo, Ding-Ding (1) 2006, 27 (4):  394-397.  DOI: - Abstract ( 288 )   HTML   PDF (187KB) ( 740 )   Describes the architecture of WebitOS. As a hierarchically modularized system with perfect function, WebitOS consists of several modules for device driver, real-time kernel and TCP/IP protocol, etc. Analyzes the realization mechanism of WebitOS kernel: employs a priority-based preemptive multi-task scheduler for real-time scheduling and uses the best-fit allocation algorithm and collection-coalition algorithm for memory management. Then, tests the performance of WebitOS kernel in view of space-time costs and support to EI application. The results show that WebitOS kernel is a real-time, simplified and effective one that is specially adoptable to embedded applications in resource-constrained environment. References | Related Articles | Metrics

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Medical image segmentation based on improved Ostu algorithm and regional growth algorithm Jiang, Hui-Yan (1); Si, Yue-Peng (1); Luo, Xing-Gang (1) 2006, 27 (4):  398-401.  DOI: - Abstract ( 457 )   HTML   PDF (222KB) ( 1420 )   A new method is proposed for automatic segmentation of edge-blurred medical images, by the which the images are compressed and dissected in multi-resolution through wavelet transform. The images are sharpened by strengthening the extremum of the high-frequents elements at each and every resolution and smoothened by neighboring average and median filtering. Then, the images are segmented automatically using the improved Ostu algorithm(maximization of interclass variance) and the regional growth algorithm through multiseed vote mechanism and, according to the segmenting effect, the threshold is controlled iteratively to evaluate the mean minimum distance with the error found in between the region segmented automatically and that segmented manually. The method proposed has been applied to 30 edge-blurred abdominal MRI images and proves its effectiveness for complex image segmentation. References | Related Articles | Metrics

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Linear optimization algorithm of grid resource allocation on user demand Zeng, Wan-Dan (1); Chang, Gui-Ran (1); Yu, Zhen-Lei (1); Zheng, Xiu-Ying (1) 2006, 27 (4):  402-405.  DOI: - Abstract ( 193 )   HTML   PDF (733KB) ( 471 )   A new Grid resource allocation algorithm based on economy is proposed, as well as the linear optimization method for the elements in economy Grid scheduling. The user can preset the values of impact parameters for different elements and the algorithm can achieve the optimized resource allocation strategy on user demand. A mathematical model and the process description of the algorithm are thus given. Some sets of simulation are taken by GridSim to analyze and evaluate the performance of the algorithm. The performance contrast is also made with the algorithms within GridSim. References | Related Articles | Metrics

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Heat transfer of hot strip during ultra fast cooling Yuan, Guo (1); Yu, Ming (1); Wang, Guo-Dong (1); Liu, Xiang-Hua (1) 2006, 27 (4):  406-409.  DOI: - Abstract ( 353 )   HTML   PDF (338KB) ( 1201 )   Using the finite difference method, the range of average heat transfer coefficient of overall convection during ultra fast cooling (UFC) is given. For the 3-4 mm thick steel strip, the range is around (4-8) kW/(m2·K) if the range of ultra fast cooling rate is 300-400°C/s. The local heat transfer mechanism on the surface of hot strip during water cooling is analysed, and it is deemed that the key to the implementation of ultra fast cooling by the cooling system is to extend the strip surface area where the water jet showers on for heat transfer. Compared with the laminar cooling, the calculation of temperature field shows that the temperature gradient in strip thickness increases so sharply that it should be taken into account in practical application of UFC system. References | Related Articles | Metrics

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Temperature evolution and re-reddening behavior of hot rolled strip during laminar cooling Zhi, Ying (1); Liu, Xiang-Hua (1); Wang, Guo-Dong (1) 2006, 27 (4):  410-413.  DOI: - Abstract ( 533 )   HTML   PDF (271KB) ( 1234 )   Analyzes the temperature field of hot rolled strip during laminar cooling by finite element method, and calculates the cooling rate at typical positions to investigate how the cooling rate variea periodically during water cooling and subsequent re-reddening. It is found that there is a critical line of cooling rate at the position that is sectionally 1/3 half-thickness away from the strip surface, and the cooling rate varies alternately between positive and negative values between the surface and the critical line. It implies that the critical line is in fact a demarcation line between the transient heat output zone and input zone (re-reddening zone) in cooling process. A regression model for the relationship among re-reddening temperature, time and distances from different node points to the surface is thus obtained in re-reddening zone. The results can be used as reference for the prediction and control of microstructures and properties of strips in rolling process. References | Related Articles | Metrics

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Development of a 800 MPa dual-phase and low yield ratio heavy steel plate Zhang, Pi-Jun (1); Liu, Xiang-Hua (1); Wang, Guo-Dong (1) 2006, 27 (4):  414-417.  DOI: - Abstract ( 238 )   HTML   PDF (429KB) ( 497 )   Rolling and cooling experiments were carried out for the microalloyed HSLA steel of which the elementary composition is Fe-0.1C-Mo, and its morphology and microstructures were analyzed. The effects of deformation and cooling parameters on the yield ratio, Charpy notch impact toughness and elongation of the steel were investigated. It was found that a precise control of its strength, ductility and yield ratio can be achieved through a properly changed combination of rolling and cooling parameters. The yield ratio of the developed grade 800 MPa tensile strength heavy steel plate is controlled below 0.75 with excellent low-temperature impact toughness provided. Mainly its metallographic structure consists of acicular ferrite and martensite. References | Related Articles | Metrics

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Study on new-generation hot rolled TRIP steel Liu, Jian-Xun (1); Li, Zhuang (1); Wu, Di (1); Chi, Wei-Fan (2) 2006, 27 (4):  418-421.  DOI: - Abstract ( 405 )   HTML   PDF (501KB) ( 675 )   The Si-Mn TRIP steel for which the austempering is done after hot rolling was investigated. Its mechanism of transformation induced plasticity (TRIP) was discussed by testing the microstructure and mechanical properties of the steel. The results showed that the strain-induced transformation into martensite from residual austenite is found in hot-rolled Si-Mn TRIP steel which reveals a proper combination of ultimate tensile strength with total elongation when it is held at the bainite transformation temperature after hot deformation. The stability of residual austenite becomes higher with the increasing isothermal holding time but, if the time increases further, the stability becomes lower. Its mechanical propertie shows optimal if holding 25 min, i.e., the tensile strength, total elongation and balanced strength-ductility are up to 774 MPa, 33% and 25542 MPa%, respectively. References | Related Articles | Metrics

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Stabilizing fluctuation of Al(OH)3 particle size in seeded precipitation of sodium aluminate solution Wu, Yu-Sheng (1); Bi, Shi-Wen (1); Tong, Zhi-Fang (2); Yang, Yi-Hong (1) 2006, 27 (4):  422-425.  DOI: - Abstract ( 317 )   HTML   PDF (797KB) ( 621 )   To solve the problem of periodically explosive attenuation of Al(OH)3 particles in seeded precipitation process of sodium aluminate solution, the effects of additives used, adding amount of fine seeds and carbonization seeds on Al(OH)3 particle size were investigated under industrial conditions modeled in laboratory. The results indicated that combining properly additives used with the control of seed size is able to reduce the amplitude of periodical fluctuation and shorten the time required for Al(OH)3 particle size attenuation. The distribution of dissolvent seed size becomes more uniform by replenishing fine seeds, thus enabling the periodical fluctuation of Al(OH)3 particle size to be attenuated. Moreover, adding partly carbonization seeds in seed precipitation process can acquire more stable Al(OH)3 products. References | Related Articles | Metrics

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Experimental investigation on gold recovery from high-As concentration through bio-oxidation/cyanidation with thermophilic bacteria Yang, Hong-Ying (1); Gong, En-Pu (2); Zi, Jian-Wei (1); Yang, Li (1) 2006, 27 (4):  426-429.  DOI: - Abstract ( 253 )   HTML   PDF (1012KB) ( 659 )   HQ-0211 thermophilic bacteria, as an excellent strain for microbial leaching, is highly resistant to arsenic and suitable for the refractory high-As gold concentration. The bacteria was used experimentally to preoxidize the gold concentration in which the As content is 11.78 wt% for 6 days. The As content thus lowers to 0.02 wt% with an As mass concentration 11.41 g/L in solution, dearsenification rate 99.24% and weight loss rate 63.38%. After the preoxidation by HQ-0211, the gold recovery is improved greatly, i.e., up to 92.12% from 18.25% that was simply cyanided. The experimental result showed that the bio-oxidation-cyanidation process is highly adaptable to such gold concentration with high As content, for example, up to 11.78 wt%. In addition, in the process no other additives is required for dearsenification, and the process offers such advantages as short time for bio-oxidation and good effect of desulfurization. References | Related Articles | Metrics

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Investigation on nonequilibrium near-liquidus casting of thixotropic magnesium-rare earth base alloys Zhang, Zhi-Qiang (1); Le, Qi-Chi (1); Wang, Zhong-Jun (1); Cui, Jian-Zhong (1) 2006, 27 (4):  430-433.  DOI: - Abstract ( 253 )   HTML   PDF (543KB) ( 902 )   Nonequilibrium near-liquidus casting (NNLC) is such a process that the casting should be carried out near the nonequilibrium liquidus temperature which was determinated by the cooling curve of melt in a nonequilibrium solidification process. It is substantially a near-liquidus casting. The results of investigation on ZK60 magnesium-rare earth base alloys made with the process indicated that the refined and homogeneous non-dendritic microstructure can be obtained. Therefore, it is an effective way for thixotropic semi-solid magnesium alloy melt. For the ZK60-base alloys, different alloying additions have different obvious effects on the nonequilibrium liquidus and microstructure of near-liquidus castings. For instance, Ag, Y, Nd and other REs all are beneficial to avoiding the occurrence of intracrystalline liquid. Among them RE-containing addition is most beneficial to the spheroidization of primary grains, but Nd makes them inhomogeneous. Although Ag and Y make primary grains less spheroidized than what Nd offers, they serve the function of homogenization and dendrite regression. References | Related Articles | Metrics

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Li1+xV3O8 as cathode material synthesized through solid-state reaction for lithium-ion battery Liu, Li-Ying (1); Tian, Yan-Wen (1); Xu, Cha-Qing (1); Zhai, Yu-Chun (1) 2006, 27 (4):  434-437.  DOI: - Abstract ( 270 )   HTML   PDF (117KB) ( 654 )   Li1+xV3O8 as cathode material for lithium-ion battery was synthesized through a solid-state reaction method with Li2CO3 and V2O5 as raw materials. The influence of synthetic conditions on the structure, conductivity and electrochemical properties of Li1+xV3O8 specimens was investigated by means of TG-DTA, XRD, AC impedance and galvanostatic charge-discharge tests. XRD results indicated that the relative intensity of the (100) diffraction peak of specimens increases with sintering temperature, thus lengthening the path to intercalate and deintercalate Li+ ion from Li1+xV3O8. The AC impedance testing showed that the conductivity increases with sintering temperature, and the conductivity tends to increase first then decrease with sintering time. Electrochemical testing results indicated that the cathode material sintered at 580°C for 20 hr in air has better electrochemical properties with a maximum discharge specific capacity up to 254.0 mAh·g-1 which will be kept at 245.6 mAh·g-1 after 10 cycles. All the testing results showed that the synthesis process proposed can provide an cathode material superior than that prepared by high-temperature melting process. It's really an ideal process. References | Related Articles | Metrics

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Effect of Ca on microstructure and mechanical properties of Mg-Li-Zn alloy Li, Hong-Bin (1); Yao, Guang-Chun (1); Ji, Hai-Bin (1); Liu, Yi-Han (1) 2006, 27 (4):  438-441.  DOI: - Abstract ( 230 )   HTML   PDF (1754KB) ( 503 )   Mg-9wt%Li-2wt% Zn alloy was prepared with 0.1-0.5wt% Ca as alloying addition and cast in laboratory to investigate its effect on the alloy. The alloy plates have excellent cold-workability and can be rolled to 2mm-thin sheets at room temperature. Effect of Ca on the microstructure and mechanical properties of the sheets was investigated. Uniaxial tension test was carried out at room temperature and the results showed that adding Ca can improve the mechanical properties. The tensile strength and elongation of the sheets are increased by 19% and 6%, respectively, when Ca content is 0.1wt%, while the tensile strength increases slightly and elongation decreases with further increasing Ca content. In addition, Ca can offer grain refinement to the microstructure especially when Ca content is 0.1wt%. The reason of grain refinement is the absorption of Ca at grain boundary, which further improves the mechanical properties of the sheets. References | Related Articles | Metrics

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Elastic analysis of rectangular overhanging plates Yu, Zheng-Wen (1); Guo, Hao (1); Xie, Li-Yang (2) 2006, 27 (4):  442-445.  DOI: - Abstract ( 277 )   HTML   PDF (155KB) ( 427 )   In the theory of elastic thin plates, to solve the problem of rectangular overhanging plates with complicated boundary conditions is very hard for long. A concept named modified or generalized simply supported edges is therefore introduced, i.e., superimposing altogether the solutions to the rectangular plate with four simply supported edges on which the uniformly distributed load locally acts, to the rectangular plate with four simply supported edges of which one of them is under the action of distributed bending moment and to the rectangular plate with various generalized simple supported edges and then taking the continuity condition of boundary, so as to let the result of superimposition satisfies all boundary conditions, an analytic solution is given to the rectangular overhanging plates on which any kinds of loads are acting. As an example, a specific problem that the uniformly distributed load acts on the overhanging section of rectangular overhanging plates is solved, and the solution to it is compared with the result of finite element method. It is proved that the method proposed is so effective to obtain an analytic solution to the rectangular overhanging plates with complicated boundary conditions. References | Related Articles | Metrics

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FE mesh generation method and quasi-static analysis of rotor blades Zhou, Sheng-Tian (1); He, Wei (1); Huang, Bao-Zong (1) 2006, 27 (4):  446-449.  DOI: - Abstract ( 177 )   HTML   PDF (979KB) ( 602 )   With rotor blade taken as an example, the difficulties of auto-generating shape-rational EF meshes and limitation of conventional methods were discussed when the discrete objects are geometrically complex and only one kind of elements is used, such as hexahedron element. Based on the geometrical characteristics of blades, some practical techniques were proposed, including 2D-series-connection numbering of sub-block nodes, application of generalized quadrilaterals and interpolation method of node coordinates on complex surfaces. They have been applied to the meshes of an actual blade, which is automatically generated by means of a 20-node iso-parametrical hexahedron element. The finite element discretion of the blade shows that the proposed techniques can provide better meshes than that generated by some common analysis softwares and make up for the defects of conventional ones. They are simple and effective and may be widely used in some EF programs for special purpose. References | Related Articles | Metrics

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Analysis on stability of top pillar when coming into underground mining from open-pit Ma, Tian-Hui (1); Tang, Chun-An (1); Yang, Tian-Hong (1); Lin, Peng (2) 2006, 27 (4):  450-453.  DOI: - Abstract ( 291 )   HTML   PDF (885KB) ( 512 )   Based on the site-specific conditions, the physico-mechanical properties and structural features of rock and mining conditions, the 3-D numerical analysis softwares MSC. PATRAN and MSC. NASTRAN were first used to model wholly the Shirengou Iron Mine. Readjusting repeatedly the parameters of the models, the 9 proposed schemes were simulated and analyzed individually and compared with each other. It was concluded that the 9th scheme can make the top pillar stable, and an optional mining program and some measures were proposed in detail to control effectively the spalling and caving of rock mass. It also provided a reliable analytic method and scientific evidence for choosing reasonable dimension of top pillar when coming into underground mining from open-pit. References | Related Articles | Metrics

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Grey decision-making for constructional parameters of non-pillar sublevel caving in Zhangjiawa iron mine Zhang, Guo-Lian (1); Qiu, Jing-Ping (1); Song, Shou-Zhi (1) 2006, 27 (4):  454-457.  DOI: - Abstract ( 268 )   HTML   PDF (152KB) ( 685 )   Taking the conditions of the medium ore body of -250 m phase in Zhangjiawa Iron Mine as background, a simulating experiment was carried out with different constructional parameters for non-pillar sublevel caving. Introducing the grey decision-making theory in the optimization of constructional parameters, the problem to transform multi-object optimization including the rates of ore recovery, undiluted ore recovery and rock drop-in into a single-object optimization was successfully solved. According to the experimental results, it was found that such optimum constructional parameters as sublevel height, drift interval and drawing pace are 12.5 m, 12 m and 4-5 m, respectively, for the non-pillar sublevel caving of the medium -250 m phase. The investigation provides not only a foundation on which the design of mining preparation is available but also a new approach to the optimization of mining engineering. References | Related Articles | Metrics

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- - 2006, 27 (4):  458-461.  DOI: - Abstract ( 248 )   HTML   PDF (165KB) ( 402 )   - References | Related Articles | Metrics

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Study on infrared spectra of acicular nanoparticles of calcium carbonate powder Li, Li-Juan (1); Sun, Feng-Jiu (1) 2006, 27 (4):  462-464.  DOI: - Abstract ( 269 )   HTML   PDF (264KB) ( 1847 )   Nanoparticles of calcium carbonate powder prepared by liquid phase process were characterized by XRD, TEM and IR. The results of XRD and TEM showed that the nanoparticles are acicular and highly dispersive and belong to the calcite structure of hexagonal system. The IR spectra revealed that blue shifts are found to different degrees at three absorption peaks among which the C-O peak at 1437.3 cm-1 showing retractable vibration is most obvious, where the blue shift is 30 cm-1 with strong wideband absorption. Discusses in detail the change in infrared spectra of CaCO3 powder. References | Related Articles | Metrics

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Rapid synthesis of superconducting Bi2Sr2CaCu2Oy powders by sol-gel method Qi, Yang (1); Chen, Wan-Shi (1); Zhang, Cai-Bei (1); Yang, Hua-Zhe (1) 2006, 27 (4):  465-468.  DOI: - Abstract ( 243 )   HTML   PDF (793KB) ( 464 )   The high-purity Bi2Sr2CaCu2Oy(Bi-2212) superconducting powder was synthesized rapidly via sol-gel. Metal nitrates were used as reactants with ethylenediaminetetracetic acid (EDTA) used as complexant to prepare primary gel, and the secondary gel was prepared via heating further the primary one. Then, the above two types of gel were sintered separately at 850°C for 10 h. The results of X-ray diffraction (XRD) revealed at that the phase of Bi-2212 can be formed by way of using either primary or secondary gel, but the secondary one is preferable to form the Bi-2212 superconducting single phase. References | Related Articles | Metrics

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Effect of temperature rising rate on thermolysis reaction kinetics of β-CD/1-MCP He, Yi (1); Sun, Ting (1) 2006, 27 (4):  469-472.  DOI: - Abstract ( 230 )   HTML   PDF (1020KB) ( 604 )   The inclusion complexes of β-CD and 1-MCP were studied by temperature-programmed themogravimetry, from which the TG/DGT spectra were obtain at a temperature rising rate 10-40 K/min. The DTG parameters, Tm and (dα/dT)m, and kinetic parameters were calculated from Freeman-Carroll method and Kissinger method, respectively, both were affected by temperature rising rate. The results showed that the thermal kinetic parameters Tm and (dα/dT)m increase linearly with the rate. From the results by Freeman-Carroll method, it can be found that there is a kinetic compensation effect which reveals a linear relationship: InA=0.1059E+1.013. However, if by Kissinger method, several temperature rising rates are used to calculate the activation energy depending on how to combine these rates together. References | Related Articles | Metrics