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15 August 2007, Volume 28 Issue 8 Previous Issue    Next Issue
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Discretization of continuous-time T-S fuzzy system: Delta operator approach Yang, De-Dong (1); Zhang, Hua-Guang (1) 2007, 28 (8):  1065-1068+1072.  DOI: - Abstract ( 281 )   HTML   PDF (1328KB) ( 776 )   The Delta operator approach is used to discretize a class of continuous-time T-S fuzzy systems. The linear time-invariable dynamic equation in the post-part of fuzzy rule is discretized locally, and then the fuzzy dynamic model of the system is discretized globally. To acquire the polyhedral structure of T-S fuzzy systems, the global discretization model is expanded using Taylor series to obtain an approximate global discretization model. Based on linear matrix inequality (LMI), a state-feedback controller is designed corresponding to approximate global discretization model so as to stabilize asymptotically the closed-loop system. Using the Delta operator to discretize the continuous systems, the discretization model tends to approach to the original continuous model with the increasing sampling frequency, while the original dynamical property is kept up. The simulation result verifies theoretically the validity of the approach proposed. References | Related Articles | Metrics

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Robust stability of BAM neural networks with delays Guan, Huan-Xin (1); Wang, Zhan-Shan (1); Zhang, Hua-Guang (1) 2007, 28 (8):  1069-1072.  DOI: - Abstract ( 236 )   HTML   PDF (165KB) ( 562 )   Stability problems are studied for the BAM (bi-directional associative memory) neural networks with time-varying delays, based on the linear matrix inequality technique. Using Lyapunov stability theory and constructing a suitable Lyapunov-Krasovskii functional, two new criteria are given to ensure the global robust stability of the equilibrium point in a BAM neural network with uncertainty. As a result in form of linear matrix inequality, it is easy to verify and independent of the magnitude of the time-varying delays. The magnitude becomes greater if the time-varying delay is short, then the result shows less conservative than the delay-dependent stability as shown in earlier works. A simulation example is given to illustrate the effectiveness of the result. References | Related Articles | Metrics

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LMI approach of decentralized connective stabilization for expanded structure of large-scale systems Li, Xiao-Hua (1); Zheng, Xiu-Ping (1); Xu, Shao-Chuan (2); Wu, Li-Juan (2) 2007, 28 (8):  1073-1076+1080.  DOI: - Abstract ( 201 )   HTML   PDF (268KB) ( 637 )   The decentralized connective stabilization problem of the expanded structure of large-scale systems is considered. It is assumed that a large-scale system is constituted by adding new-subsystems iteratively on the original one, i.e., an expanded system. Then, the decentralized connective stabilization problem of the system becomes how to design the local control law of the new subsystems without changing the decentralized control laws of original structure. Therefore, the subsystems and, as a result, the expanded system are both stable and connectively stable. The sufficient condition for the decentralized connective stabilization of the expanded structure of large-scale systems is obtained by use of Lyapunov theory and LMI approach. The design method of the decentralized stabilization controller of the expanded structure is given. A numerical example shows the effectiveness of the method proposed. References | Related Articles | Metrics

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Error analysis and application of cross-ratio invariant to machine vision Guo, Yang (1); Xu, Xin-He (2) 2007, 28 (8):  1077-1080.  DOI: - Abstract ( 399 )   HTML   PDF (1124KB) ( 604 )   Based on a linear pinhole camera imaging model, the crass-ratio invariant has been applied to pattern recognition on computer vision for a long time as the most fundamental projective invariant. Then, the error of cross-ratio invariant is proposed and studied. Analyzing the influence of image noise on cross-ratio accuracy, the upper limit and lower limit of error are both obtained. According to the cross-ratio invariance, a new well-simplified artificial landmark pattern is designed to provide very high robustness for detecting under all kinds of viewing angles and illuminant conditions. The detection results of real images showed that the new artificial landmark pattern based on cross-ratio invariant is easy to detect fast and accurately. Landmark pattern is of practical importance in application to the self-localization and the navigation of a single-view autonomous mobile robot based on artificial landmark. References | Related Articles | Metrics

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Gait planning and control implementation of biped robot with heterogeneous legs Li, Fei (1); Xie, Hua-Long (2); Xu, Xin-He (1) 2007, 28 (8):  1081-1084.  DOI: - Abstract ( 248 )   HTML   PDF (1276KB) ( 892 )   To provide an ideal testing platform to develop intelligent bionic legs, a new mode of humanoid biped robot with heterogeneous legs (BRHL) is proposed. Describes the concept of BRHL and what it can offer for such development. Based on the idea of segmentation modeling, a coordinated kinetic model is given to BRHL. A modified Sigmoid model of magneto-rheological damper (MR damper) is proposed with modeling test done. Then, based on gait tracking, the gait planning of BRHL is described in detail for simulation. With the BRHL control system designed, the softwares Pro/E, ADAMS and MATLAB/Simulink are used to simulate the combined control with virtual prototype robot. The result indicates that intelligent bionic leg controlled by MR damper can track the artificial leg's gait well. References | Related Articles | Metrics

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Embedded intelligent monitor-control network based on multiple protocols Zhang, Yun-Zhou (1); Wu, Cheng-Dong (1); Xue, Ding-Yu (1); Liu, Meng (1) 2007, 28 (8):  1085-1089.  DOI: - Abstract ( 234 )   HTML   PDF (448KB) ( 783 )   Proposes and designs an intelligent embedded monitor-control network to implement the real-time monitoring for different large buildings and building groups. Aiming at the specific property of the system, multiple protocols and field bus are used to form a distributed monitor-control network based on embedded system so as to play fully the role of different protocols and field bus. Taking a high-performance micro-processor as the core, the system architecture and communication center are implemented with the multi-layer logic process. The bus protocol stack is introduced to attain the high transfer speed among protocols. An improved data communication protocol is therefore used for resolving the data loss problem of multi-host communication. The system acquires high intelligence, low cost and excellent flexibility, thus verifying that multiple protocols are useful for this system. References | Related Articles | Metrics

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Black and white X-corner detection algorithm Liu, Yang (1); Wang, Fu-Li (1); Chang, Yu-Qing (1); Lu, Zhe (1) 2007, 28 (8):  1090-1093.  DOI: - Abstract ( 923 )   HTML   PDF (240KB) ( 3088 )   Analyzes the shortcomings of the present X-corner detection algorithm for B/W squares on chessboard and proposes a new one in which a new BW corner detection operator is used to check out the gray values' distribution in 4 characteristic directions as defined. The coordinates of those corners are obtained with the precision at pixel level. The corner coordinates are revised to implement their localization at sub-pixel level in accordance to the similarity and influencing factors indicated in local windows. The algorithm is robust to the rotation and brightness transformation of images, and it has been applied to the X-corner images on real photos and, as a result, its validity and practicability are verified. References | Related Articles | Metrics

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Equilateral triangle localization algorithm based on average RSSI Zhu, Jian (1); Zhao, Hai (1); Sun, Pei-Gang (1); Bi, Yuan-Guo (1) 2007, 28 (8):  1094-1097.  DOI: - Abstract ( 669 )   HTML   PDF (332KB) ( 3726 )   To get high precision of localization in WSNs (wireless sensor networks), an equilateral triangle localization algorithm based on average RSSI is brought up, taking account mainly of the measurement precision and improvement of the distribution of beacon nodes. This algorithm presents two concepts: sensitive region and insensitive region of RSSI. It introduces Gauss model to deal with the RSSI which is got from in sensitive region, then the problem that RSSI is easy to be interfered is resolved. And the equilateral triangle distribution model is used to deal with the distribution of beacon nodes to ensure that the tracks of unknown nodes are always kept within the insensitive region, thus improving the measurement precision. A conclusion is drawn that the Gauss model can screen out the first-class RSSI well and the equilateral triangle distribution model can improve the acquisition precision. This algorithm is easy to implement and no communication expense and extended hardware are required. References | Related Articles | Metrics

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Iris recognition by restructuring characteristic vector field Zhang, Xiang-De (1); Cao, Yu (1); Wang, Qi (1); Tang, Qing-Song (1) 2007, 28 (8):  1098-1100.  DOI: - Abstract ( 259 )   HTML   PDF (753KB) ( 577 )   Relating the iris recognition to the working mechanism of human brain, a method of restructuring the characteristic vector field is recommended. It calculates the lst-order differences separately from the rows of one normalized iris image and columns of another one, then the two differences are mapped to form a vector field. Based on the restructuring idea, the lst-order differences are further calculated from the rows of an iris image and from the columns of another iris image for restructuring a new characteristic vector field. Then, whether the two iris images are resulting from the same iris is judged by computing the restructuring distance between the two fields. Comparing the method with some other existing ones, it shows the advantage that its preprocessing procedure does not require denoising and image enhancing but reduces the time for computation. Moreover, because there is no filter in integral form used during computation, the method is adaptable to hardware implementation. With the match test done 285, 290 times, it was revealed that the rate of correct recognition is up to 98.81% by use of this method, thus verifying its validity. References | Related Articles | Metrics

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Grid-based multi-strategy algorithm for association rules mining Wang, Gang (1); Wen, Tao (1); Guo, Quan (2); Ma, Xue-Bin (1) 2007, 28 (8):  1101-1104.  DOI: - Abstract ( 254 )   HTML   PDF (199KB) ( 497 )   Knowledge grid is analyzed comprehensively and then a grid-based MBHD (multi-strategy based hybrid distribution) algorithm is put forward in view of the heterogeneous, dynamic and distributive characteristics of grid. The optimization policy of market mechanism is integrated with timestamp mechanism and token-ring policy in MBHD algorithm to solve efficiently the problem of network load balance due to the restricted algorithms in grid and avoid the formation of unnecessary network load and competition. The time spending as a problem crucial to the algorithm for association rules mining is thus solved with the efficiency and performance improved. Testing results show the MBHD response time performance corresponding to different numbers of processor nodes and minimum support, which is compared with CD, IDD and HD algorithms. A conclusion is reached that the MBHD algorithm is highly adaptable to the characteristics of grid as a platform with its performance especially the expandability improved greatly. References | Related Articles | Metrics

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Chaos-based predictive algorithm for continuous aggregate queries over data streams Yu, Ya-Xin (1); Wang, Guo-Ren (1); Chen, Can (1); Fu, Chong (1) 2007, 28 (8):  1105-1108.  DOI: - Abstract ( 332 )   HTML   PDF (337KB) ( 584 )   CSPA (chaotic stream predictive algorithm) is proposed to predict efficiently the prospective aggregate values of the aggregate queries which are continuous and over data streams, based on the theory of chaos. Regarding the data stream as a time series where all the arrival times of data are arranged in order, the prediction of the prospective aggregate values of continuous aggregate queries is discussed in view of the conventional analysis of time series. However, a data stream series differs greatly from conventional time series in both time interval and data set processing, the moving window technique is therefore used for stream processing. In addition, the influence of the complex inherent nonlinear dynamic characteristics in streaming data on the prediction had not been considered in relevant earlier works. So, CSPA makes use of the idea about local prediction included in the theory of chaos to make up for the deficiency. Experimental results showed the high exactness of using the CSPA algorithm. References | Related Articles | Metrics

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Clustering result evaluating algorithm in a gravitational way Yu, Yong-Qian (1); Zhao, Xiang-Guo (1); Chen, Heng-Yue (1); Wang, Guo-Ren (1) 2007, 28 (8):  1109-1112.  DOI: - Abstract ( 319 )   HTML   PDF (259KB) ( 1045 )   A clustering result evaluating algorithm is presented in a gravitational way, where all the data points in the data space are regarded as the particles assigned with unit mass. The quality of such a clustering result is evaluated through analyzing the gravitational relation between different data points in the clustering result in which the greater the gravitation between data points, the smaller the gravitation acted on noise data points-this is regarded as a quality result and vice versa. Experiments conducted on several datasets verify the validity and high efficiency of the proposed algorithm which can get an evaluation value to reflect whether the clustering result is of good or poor quality. Furthermore, the proposed algorithm can lead the clustering algorithm to find the best result automatically without any manual interference. References | Related Articles | Metrics

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Performance of space-time block code in frequency-selectivity fading channel Sha, Yi (1); Wang, Bin (1); Li, Na (1); Wang, Guang-Xing (1) 2007, 28 (8):  1113-1117.  DOI: - Abstract ( 283 )   HTML   PDF (575KB) ( 907 )   To discuss the STBC practicability, the STBC performance in a frequency-selectivity fading channel is studied. A simulation model in the channel is developed using SIMULINK, which comprises a channel, transmitting end and receiving end, where the channel comprises a multipath Rayleigh channel and Gaussian white noise; the transmitting end comprises a serial-parallel converter and space-time block coder with spectrum spread and signals disturbed; the receiving end uses an ideal RAKE receiver. The simulating results showed that when a channel varies slowly the BER (bit error rate) falls down obviously and while it varies quickly the BER rises up somewhat, and either the falling or rising occurs with the increasing number of channel paths. And the more the number of paths is, the clearer the BER rises up. References | Related Articles | Metrics

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Parallel simulation algorithm for overlay network Zhao, Yu-Hui (1); An, Yu-Yan (2); Sun, Lu-Wei (1); Gao, Yuan (1) 2007, 28 (8):  1118-1121.  DOI: - Abstract ( 295 )   HTML   PDF (339KB) ( 919 )   The existing simulators will cost dear when simulating an overlay network which is extending with relevant nodes taking dynamically part in the simulation. A DEVS-based distributed parallel simulation algorithm is therefore proposed to simulate the overlay network protocols, and it has been used to evaluate the performance of layered overlay multicast network (LOMN). According to the overlay network protocols defined by users and their application requests, the algorithm is described to produce several discrete event payloads and dispense them to the simulator on different hosts, then the cooperative simulation jobs are executed in a parallel way. Compared with the simulator models at data packet levels, the algorithm has advantages of reducing the simulating cost and more adaptable to simulating the large-scale and dynamic overlay network protocols and applications. It is available to solve better the challenges the overlay network simulation is facing: scalability and dynamic change of network. References | Related Articles | Metrics

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Benefit function-based replication strategies in data grids You, Xin-Dong (1); Chen, Xue-Yao (3); Zhu, Chuan (1); Chang, Gui-Ran (2) 2007, 28 (8):  1122-1126.  DOI: - Abstract ( 290 )   HTML   PDF (468KB) ( 490 )   Analyzing the features of some typical replication strategies in a collaborative data grid environment and building a benefit function that implies the collaboration among grid nodes to replace local data replication, a replication strategy is proposed taking the benefit function as basis. The results of an experiment done on the grid simulator OptorSim showed that the replication strategy proposed can shorten the time required for system response in addition to the reduced utilization of network and economized consumption of bandwidth/storage resource in comparison with some economy-based replication strategies, thus improving the system performance. The validity of the strategy is verified. References | Related Articles | Metrics

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Microstructure and properties of semi-solid ZL116-alloy die forgings Dong, Wei-Guo (1); Wang, Ping (1); Lu, Gui-Min (1); Zuo, Liang (1) 2007, 28 (8):  1127-1130.  DOI: - Abstract ( 265 )   HTML   PDF (622KB) ( 768 )   Die forging tests were conducted on a 300 t press to form semi-solid ZL116-alloy parts. The results showed that the die forging process is suitable for semi-solid metal because the parts thus formed show compact structure and clear shape with die space fully filled up. The microstructure of such parts is mainly the fine and uniformly distributed near spheroid and non-dendritic rosette. In addition, plastic deformation was found locally under the action of static pressure for part forming, which makes the mechanical properties of semi-solid die forgings superior to that of die castings formed from liquid, e.g., their hardness comes to 65.7 HB or 20.5% higher than die castings. The testing results lay down a foundation for applying such parts to military vehicles. References | Related Articles | Metrics

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Effect of magnetic annealing on recrystallization texture and microstructure of non-oriented silicon steel Zhou, Shi-Chun (1); Pei, Wei (1); Sha, Yu-Hui (1); Zuo, Liang (1) 2007, 28 (8):  1131-1135.  DOI: - Abstract ( 638 )   HTML   PDF (1649KB) ( 664 )   Cold-rolled non-oriented silicon steel sheets were annealed conventionally and magnetically at 0.1, 6 and 12 T, where the magnetic field was applied to them in the rolling direction. The results showed that the magnetic annealing process affects obviously the orientation density of recrystallization texture and grain size, and the annealing effect presents a nonlinear relationship with magnetic induction. Magnetic annealing tends to strengthen the favorable η (<00l> RD) and {100} fibers and weaken the unfavorable γ fiber, and the magnetic field at 6 T is more effective to optimize texture. Recrystallization grain size becomes larger under annealing at 6 T and smaller at 0.1 T in comparison with conventional and high field (12 T) annealing. A magnetic annealing mechanism is therefore proposed in view of lowering the grain boundary mobility and providing an additional orientation-dependent driving force for grain boundary migration. References | Related Articles | Metrics

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Preparation of Ni-based alloy coating on Cu-alloy surface through laser-induced reaction in-situ Chen, Sui-Yuan (1); Liu, Da-Liang (1); Liu, Chang-Sheng (1); Liu, Fang (1) 2007, 28 (8):  1136-1139.  DOI: - Abstract ( 248 )   HTML   PDF (825KB) ( 540 )   The newly developed Ni-based alloy containing a certain amount of Al nanopowder was taken to prepare a ceramic-phase coating on Cu-Cr alloy surface through pulse laser-induced reaction in-situ. The microstructure morphology and coating mechanism was studied experimentally. The result showed that under condition of optimized process parameters of the laser-induced reaction in-situ, a bonding interface forms between the substrate and coating, which consists of both coating and substrate elements in form of refined grains. The Al nanopowder can offer more energy to promote the formation of coating, while the cladding structure is reinforced by the ceramic grains whose size are less than 10 μm. The Al nanopowder/RE oxides added in coating serve the function of reducing the formation of cracks/pores. As a result, the average microhardness of the coating is 340 HV instead of 85 HV which is that of the substrate without coating. References | Related Articles | Metrics

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Application of improved BP neural network to final sulfur content prediction of hot metal pre-desulfurization Zhang, Hui-Shu (1); Zhan, Dong-Ping (1); Jiang, Zhou-Hua (1) 2007, 28 (8):  1140-1142.  DOI: - Abstract ( 226 )   HTML   PDF (747KB) ( 464 )   A prediction model of final sulfur content is developed for hot metal pre-desulfurization by use of an improved BP neural network, especially for the desulfurization process by CaO+Mg powder co-injection in Benxi Steel Co. Ltd. To overcome the disadvantages of overmuch iterative repetition and slow convergence rate of normal BP algorithm, an approach to readjust adaptively the self-learning rate with self-learning for maximum error is used to improve the normal BP algorithm during modeling. The data from 1900 heats are used to train the model with other 100 heats randomly picked out as test samples. Test results showed that 12% of the predicted values got from the 100 samples are the same to the actually measured values, 89% have the error within 0.003% and the average error is 0.0020%. References | Related Articles | Metrics

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Large eddy simulation for flow field in centrifugal tundish Wang, Fang (1); Li, Bao-Kuan (1); Shen, Feng-Man (1) 2007, 28 (8):  1143-1146.  DOI: - Abstract ( 212 )   HTML   PDF (701KB) ( 713 )   To study the flowing process of molten steel in centrifugal tundish, the LES (Large Eddy Simulation) is used to investigate the structure of flow field in three cases, i.e., (a) tapping through a straight stopper nozzle by electromagnetic force; (b) tapping through a curved stopper nozzle by the gravitational potential of molten steel; (c) tapping through curved stopper nozzle by electromagnetic force, in this way, the process parameters due to flow structure in tundish and eddy intensity are both affected by the co-action of electromagnetic force and stopper nozzle. The results show that LES can simulate successfully the 3-D turbulent flow field in centrifugal tundish. In comparison with the tapping depending singly on either electromagnetic force or curved stopper nozzle, the co-action of rotary electromagnetic force and curved stopper nozzle can enhance significantly the horizontal eddy intensity. It is revealed that changing the straight stopper nozzle to a curved one can increase the whirling speed byl5%-19% in flow field if the electromagnetic force remains unchanged. References | Related Articles | Metrics

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Corrosion behavior of hot-dip galvanized sheet steel in different sea water zones in Qingdao Li, Xin (1); Li, Yan (2); Wei, Xu-Jun (1) 2007, 28 (8):  1147-1151.  DOI: - Abstract ( 360 )   HTML   PDF (578KB) ( 896 )   The commercial hot-dip galvanized sheet steel was investigated for its corrosion behavior in three different seawater zones in Qingdao with electrochemical measurement, weight loss test and SEM. The results indicated that zinc coating exposed to immersion zone dissolved quickly due to high corrosion current density and being hard to form a stable protective film resulting from the corrosion itself, i.e., galvanized steel under such conditions is the poorest one in corrosion resistance. Biofouling often takes place on galvanized steel surface exposed to tidal zone, which may result in partial protection to coating surface at obviously lower corrosion rate than the coupons in immersion zone. The splash zone is the least aggressive of all the seawater zones for galvanized steel with biofouling not occurring. The lowest corrosion rate of galvanized steel in splash zone may relate to the good air ventilation condition on coating surface and the protective film resulting from the oxidation itself. In comparison to the test coupons in immersion zone, the corrosion resistance of those in tidal and splash zones increases by 37% and 94%, respectively. References | Related Articles | Metrics

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Behavior of argon gas bubbles in swirlings driven electromagnetically Qi, Feng-Sheng (1); Li, Bao-Kuan (1); Chen, Hai-Geng (1) 2007, 28 (8):  1152-1155.  DOI: - Abstract ( 237 )   HTML   PDF (454KB) ( 687 )   Applying electromagnetic stirring technique to RH vacuum degassing system, how the gas bubbles move in the swirlings driven electromagnetically in the ascending pipe of RH system is investigated combining water modeling experiment with numerical simulation. Both the experiment and simulation results reveal that the gas bubbles are distributed in swirling field and bubbles' motional path presents spiral, and that the bubbles come together at the center of the pipe under the influence of swirlings. In addition, the swirlings prolong the staying time of non-metallic inclusions in RH system and then extend their motional paths, thus providing more chances for non-metallic inclusions to collide or combine with gas bubbles so as to benefit the removal of inclusions. References | Related Articles | Metrics

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Process mineralogy of refractory gold ore in Jinya, Guangxi province Yang, Hong-Ying (1); Yang, Li (1); Tong, Lin-Lin (1); Fan, You-Jing (1) 2007, 28 (8):  1156-1158+1166.  DOI: - Abstract ( 268 )   HTML   PDF (145KB) ( 1053 )   Jinya gold mine in Jinya, Guangxi Province PRC is of refractory type, in which the Au and Ag contents are 6.28 g/t and 1.37 g/t, respectively. The rest includes As 0.58wt%, S 3.10wt%, and C 1.76wt% containing TOC 0.21wt%. In the gold concentrate the Au content is 52.61 g/t, Ag 6.00 g/t, As 11.32wt%, S 29.32wt%, and C 0.35wt%. It was found that the main metallic minerals in Jinya gold ore are pyrite and arsenopyrite and the rest includes galena, sphalerite and chalcopyrite, etc. The main gold-bearing minerals are pyrite and arsenopyrite, and the occurrence form of gold in the ore is sub-micro grain gold. The main arsenic-bearing minerals are pyrite, realgar and orpiment. The objectionable constituents are arsenic, carbon-containing material and clay minerals. The characteristics of the gold ore are fine-grain granular texture and minuteness dip-dye structure. References | Related Articles | Metrics

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On the preparation process of foamed pure aluminum Li, Bing (1); Yao, Guang-Chun (1); Wang, Yong (1); Luo, Hong-Jie (1) 2007, 28 (8):  1159-1162.  DOI: - Abstract ( 251 )   HTML   PDF (317KB) ( 552 )   The foamed pure Al was prepared by way of melt foaming process. Rapid stirring to add foaming agent was used to address the difficulty that the high decomposition rate of foaming agent is unfavorable to mixing the agent homogeneously into melt when the temperature is higher than the melting point of pure Al. How the foaming time affects the quality of the foamed pure Al was investigated. The results showed that the optimal processing parameters for the preparation of high-quality foamed pure Al are as follows: the adding amount of metallic Ca as viscosifier is 2-3wt%, stirring time for favorable viscosifying effect 4-5 min, adding amount of foaming agent 1.0-1.5wt% when the melt temperature is 690-700°C, stirring speed 1500-1800 rpm, stirring time 3 min, foaming agent adding time within 1.5 min and foaming time 4-5 min. Then, the foamed pure Al just prepared is cooled naturally. The compressibility test results revealed that although compressive strength of foamed pure Al is much lower than that of Al-Si alloy foam, the former is a typical plastic foam material which provides a wide range of plasticity. References | Related Articles | Metrics

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Influences of powder particle size on preparation of foamed aluminum by powder compact foaming method Guo, Zhi-Qiang (1); Yao, Guang-Chun (1); Yu, Hai-Jun (1); Li, Hong-Bin (1) 2007, 28 (8):  1163-1166.  DOI: - Abstract ( 233 )   HTML   PDF (500KB) ( 918 )   With the powdered Al-Si alloy taken as raw material to prepare foam aluminum, the powdered alloy was classified into three powder particle sizes, i.e., d < 74 μm, 74 μm > d < 147 μm and 147 μm < d < 295 μm, and each of them was blended with the foaming agent TiH2 separately. Then they were all pressed into blanks for foaming experiments. As shown in experimental results, the occurrences of TiH2 agglomeration decreases as the powder particle size decrease and, gradually, the agglomerated particles become linear even point-like ones in blank. When the powder particle size decreases to d < 74 μm, all particles present point-like and are distributed uniformly in blank. In this way the high-quality foam aluminum can be obtained with low density, high porosity, thin pore walls, uniformly distributed pores and perfect foam growth. References | Related Articles | Metrics

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Acoustic emission real-time monitoring for fatigue damage to horizontal tails of a certain plane during functional test Wu, Ke-Qin (1); Geng, Rong-Sheng (2); Xie, Li-Yang (1); Wu, Ning-Xiang (1) 2007, 28 (8):  1167-1170.  DOI: - Abstract ( 234 )   HTML   PDF (360KB) ( 513 )   The acoustic emission (AE) real-time monitoring for fatigue damages to the horizontal tails and some inaccessible components was carried out during the functional test for a certain plane. In a noise background due to severe shock and vibration, the simulated AE sources and background noise were analyzed to pre-process the acquired data properly so as to enhance greatly the signal-to-noise ratio (SNR). Then, a trend analysis was made for the characteristic parameters of AE signals. The test results showed that in a long-time fatigue test process the background noise may change correspondingly to the change in ambient conditions, and the change in the trend analysis of the characteristic parameters of AE signals will therefore reflect properly the randomness/nonsteadiness in the changing background noise. Illustrated with the half-shaft fatigue damage, the trend of the characteristic parameters of AE signals (in hits) can reflect successfully the history of half-shaft fatigue damage. Thus, the time the initial fatigue damage starts and two symmetrical sources of fatigue damage can both be determined basically by analyzing the waveform of AE signals. References | Related Articles | Metrics

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Effect of parallel mechanism of parallel machine tool on its static stiffness Zhu, Chun-Xia (1); Zhu, Li-Da (1); Liu, Yang (1); Cai, Guang-Qi (1) 2007, 28 (8):  1171-1173.  DOI: - Abstract ( 266 )   HTML   PDF (782KB) ( 525 )   Aiming at the effect of static stiffness on the performance of PMT (parallel machine tool), the 3-TPT parallel machine tool developed by NEU is taken as the target to investigate. Analyzing theoretically the static stiffness model of the machine tool, an expression is given relevantly. Then, the stiffness of both the main frame and the whole machine tool under different forcing conditions are analyzed simulatively using the software ANSYS for large-size FEA, thus showing the low-stiffness positions and the effect of parallel mechanism on the whole machine tool. The simulating result indicated that the stiffness of a machine tool in vertical direction far exceeds that in horizontal direction and the stiffness of the whole machine far exceeds that of the main frame. It implies that the parallel mechanism enables the stiffness of machine tool to be doubled, and that the stiffness increases with the height of the position where the parallel mechanism is laid on. References | Related Articles | Metrics

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Application of FSM to open CNC system Sun, Wei-Tang (1); Liu, Yong-Xian (1); Zhang, Yu (1); Zhang, Yan-Cheng (1) 2007, 28 (8):  1174-1177.  DOI: - Abstract ( 261 )   HTML   PDF (454KB) ( 780 )   To overcome the problems of control programs which were programmed according to conventional modes, such as the poor replantability and difficult maintenance, a new approach is put forward to use FSM to develop CNC system softwares. The basic operation principle of FSM is described and a modeling scheme involving hierarchical FSM is proposed for intricate systems. Discusses the main software modules used in open CNC system software and their FSM behavior models. Then, the system restructuring mechanism based on FSM is introduced, which makes FSM available to define the functions of software components and control the partitions of logic so as to improve the flexibility in system restructuring. Furthermore, the way how to extend the function served to readjust adaptively the feed speed is studied on the basis of system restructuring mechanism of FSM. References | Related Articles | Metrics

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Research and analysis about dynamic job scheduling on MES system toward Markov decision processes Zhao, Hai-Feng (1); Jiang, Xing-Yu (1); Wang, Gui-He (1); Wang, Wan-Shan (1) 2007, 28 (8):  1178-1181.  DOI: - Abstract ( 307 )   HTML   PDF (1392KB) ( 882 )   Aiming at the characteristics of production system in an event-driven networked-manufacturing environment, the Markov decision process is extended such that the dynamic scheduling is available to be studied further in view of these characteristics. Based on the user-oriented criteria, the performance of the scheduling algorithm is appraised according to the response time of manufacture system in which there are some different rules. Then, the possibilities of optimal or satisfactory scheduling decision available to achieve within expected time are determined according to different rules on appraisal basis. Combining these rules with the actualities in production processes, a management system of dynamic scheduling command notices is designed in the networked-manufacturing environment to make the manufacturing management more informative. The system designed can reflect the real-time production information to meet users' demands, and the scheduling rules can be readjusted according to manufacturing practice to offer a scheme for scheduling decision making, thus ensuring the maximized economic benefits. References | Related Articles | Metrics

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Rock failure process analysis based on non-uniform grids Ma, Tian-Hui (1); Tang, Chun-An (2); Yang, Tian-Hong (1); Liang, Zheng-Zhao (2) 2007, 28 (8):  1182-1185.  DOI: - Abstract ( 259 )   HTML   PDF (904KB) ( 538 )   A new uncoupled method is presented to simulate rock failure process, i.e., the nonuniform grids are introduced into REPA (rock failure process analysis)system to develop some models by virtue of the excellent preprocessing functions from other commercial softwares for numerical simulation. Then, the information on the models already developed, elements, material properties, etc. is provided for RFPA system to calculate or postprocess them. To verify RFPA's reliability, this new method is contrasted with the original RFPA that based on uniform grids. Some analytic examples are given and the results show that this method not only break through the limitation of grids and models in the original RFPA but also is easy to operate. It is therefore regarded as a new way to numerical simulation worthy to apply it to rock and soil engineering and spread it out. References | Related Articles | Metrics

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On the synthesis and catchability of benzyl malonic acid Wei, De-Zhou (1); Liu, Wen-Gang (1); Sun, Ya-Guang (2); Zhu, Yi-Min (1) 2007, 28 (8):  1186-1189.  DOI: - Abstract ( 318 )   HTML   PDF (339KB) ( 761 )   Solid-state benzyl malonic acid was synthesized in laboratory with its catchability studied preliminarily. Test results showed that the acid has highest catchability for galena in comparison with that for sphalerite and smithsonite, e.g., the recovery rate of galena is over 90% by use of a very small dose of the acid whose pH value is 4-10. Its catchability is efficient to a certain extent to sphalerite of which the recovery rate decreases gradually with increasing pH value, while basically it has no catchability for smithsonite. The main cause of such results is that the O-O chelation takes place between benzyl malonic acid and Pb on galena surface so as to form six-membered ring chelate with a co-absorption between galenite ions and molecule occurring at the same time, but on sphalerite surface only the molecule absorption occurs. References | Related Articles | Metrics

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Trend analysis of climate change and its impact on geological disasters in Liaoning Fu, Jian-Fei (1); Qi, Wei (1); Wang, En-De (1); Xi, Xiao-Feng (1) 2007, 28 (8):  1190-1193.  DOI: - Abstract ( 238 )   HTML   PDF (563KB) ( 705 )   Utilizing the Liaoning Provincial Observatory's statistics in combination with the climate tendency ratio, trend coefficient and Yamamoto's climate diagnosis, the trend of climate change in the province is predicted. The spatial pattern of rainfall in different time sequences is restructured using multi-component statistical method and geostatistical interpolation method, then the possible impact of relevant climate change on something else is discussed. The results show that the climate tends to warmer and drier in the province where the warming period may be mainly in spring and winter and the drying period in summer and fall. It is predicted that the temperature catastrophe is possible and it will mainly be in summer, and a gradually decreasing trend is found to both annual mean temperature and rainfall, i.e., the former will take place from southwest to northeast and the latter from east to west. The trend coefficients of the temperature and rainfall both present the spatial variability which rnay results in increasing the occurrences of geological disaster with increasing intensities in the province. References | Related Articles | Metrics

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Experimental investigation on similarity simulation of imitative materials for high earth-filled culvert Fan, He (1); Liu, Bin (1); Wang, Cheng (1); Fan, Ze (2) 2007, 28 (8):  1194-1197.  DOI: - Abstract ( 299 )   HTML   PDF (164KB) ( 591 )   Based on similarity theory and dimensional analysis, a similarity index was deduced as a criterion to judge whether the test result is similar to the reality or not. Taking the mixture of sand, gypsum and diatomite as imitative specimens, a similarity simulation test was performed. The primary experiment was designed orthogonally where the level of similarity was controlled by a compression similarity index. Through a level-difference analysis, the importance of four influencing factors on mechanical properties were revealed as similarity indices. Then, the secondary experiment was performed with specimens' mixture ratio readjusted in a small range, thus finding out an optimal mixture ratio in conformity to the similarity indices based on required mechanical properties. In this way the orthogonally designed experiments were used instead of overall ones so as to reduce greatly the number of experiments with time saved. Experiment results showed the similar materials' mixture ratio and how the mechanical indices change, which can offer a reference to the project of which the materials to be used are similar to those in the simulation. References | Related Articles | Metrics

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On the flexural bearing capacity of steel tube members filled with bar-reinforced HS concrete Liu, Xiao (1); Wang, Lian-Guang (1); Zhang, Xiao-Fan (2) 2007, 28 (8):  1198-1201.  DOI: - Abstract ( 283 )   HTML   PDF (945KB) ( 487 )   Studies theoretically the failure modes and calculation of the flexural bearing capacity of steel tube members filled with bar-reinforced high-strength (HS) concrete under different loadings with different sectional layouts. According to the different positions of neutral axis and stress-strain relationship of 3 kinds of materials, 9 failure modes are ascertained. Based on the existing calculation of flexural bearing capacity of bar-reinforced HS concrete and taking account of the strengthened constraining effect of steel tube on concrete, the formulae of the height of compression zone and flexural bearing capacity are deduced by superposition method in limiting state for both symmetric and asymmetric composite members in pure bending state. The calculated result conforms well to earlier works and shows that the superposition method used is available and suitable for different sectional layouts. References | Related Articles | Metrics

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Solution to membership function of multiple-server fuzzy queues Wang, Shu (1); Ma, Qin-Hai (1); Guan, Zhi-Min (1) 2007, 28 (8):  1202-1204+1216.  DOI: - Abstract ( 289 )   HTML   PDF (128KB) ( 915 )   The definition of a-cut and Zadeh's extension principle are applied to transforming multiple-server fuzzy queues, of which the arrival rate and service rate are both fuzzy numbers, into conventional multiple-server queues. Then, the system eigenvalues are described separately by programming a set of parameters to solve upper and lower bounds of the relevant membership function. For instance, there is a 2-server fuzzy queues system of outpatients in a hospital, in which the average arrival rate and service rate are both regarded as trapezoidal fuzzy numbers. With a numerical computation of different α levels, the membership function of the average staying time for all the outpatients can thus be solved. This method can provide more abundant information for managerial decision-making in hospitals. References | Related Articles | Metrics

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Coordinating supply chain with revenue-sharing contract under asymmetric information Qiu, Ruo-Zhen (1); Huang, Xiao-Yuan (1) 2007, 28 (8):  1205-1208.  DOI: - Abstract ( 225 )   HTML   PDF (385KB) ( 950 )   The problem how to coordinate the supply chain with revenue-sharing contract under asymmetric information is studied, with a new model developed relevantly. In this model, the supplier as the leader has the decision-making right for wholesale price and revenue-sharing proportion, while the retailer as the follower has just the right to conceal the information on marginal cost and determine the ordering quantity. Discusses the supplier's optimal revenue-sharing strategy in case the retailer conceals the marginal cost, with a comparative analysis made under symmetrical information at the same time. A numerical simulation is done and the result shows that the supplier's optimal revenue-sharing strategy to spur retailer will pay a price for the unobservability of retailer's private information and reduce his/her profit, while the retailer can gain from that. References | Related Articles | Metrics

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Optimal decision for manufacturing-retailing supply chain using returns policy Tang, Jian-Xun (1); Zhang, Wei (1) 2007, 28 (8):  1209-1212.  DOI: - Abstract ( 228 )   HTML   PDF (172KB) ( 591 )   The coordination is studied for a single manufacturing-retailing supply chain as a system with returns policy warranted. Based on the frame of Stackelberg game, a gaming model is developed for such a supply chain system to which the market demand is supposed to be a linear decreasing function of retail price. Then, a newsboy model is developed by analyzing the optimal decisions in view of both the cooperation and non-cooperation, as well as a gaming model to reflect how the randomly disturbed market demand affects the supply chain with the coordination involved. In such a way the optimal decisions are given taking account of either the non-cooperation under which both the manufacturer and retailer can maximizing their profits or the cooperation under which the system can obtain optimal profit. Analyzing the conditions for using returns policy, the effective range is given. References | Related Articles | Metrics

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Empirical reasons for operating performance falloff of public companies in Liaoning province Gao, Ying (1); Chen, Ting-Ting (1); Huang, Xiao-Yuan (1) 2007, 28 (8):  1213-1216.  DOI: - Abstract ( 341 )   HTML   PDF (104KB) ( 561 )   The reasons why the operating performances of the public companies in Liaoning Province all felloff after IPO are analyzed with their panel data in view of their earnings, solvency, business operations and developmental capability. The nonparametric MNR method is used for stability test to ensure the reliability of the following conclusions by the analysis made, and a cross-section regression model is developed to discuss empirically the main influencing factors on the operating performances of those public companies. The results show clearly that their performance falloff were mainly due to the factors as follows: the difference in trades, ownership structure and the years they went to public, especially 2001 and 2002. It is revealed that the growth rate of net profit of industrially public companies were obviously lower than other trades. However, the state-owned stock equity was proved beneficial to improving the operating performance of public companies. Some suggestions are given on empirical basis. References | Related Articles | Metrics