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15 March 2012, Volume 33 Issue 3 Previous Issue    Next Issue
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Robust and non-fragile H∞ control for nonlinear descriptor discrete interval systems Su, Xiao-Ming (1); Liu, Fang-Ling (2) 2012, 33 (3):  305-309.  DOI: - Abstract ( 526 )   HTML   PDF (322KB) ( 560 )   The problem of robust and non-fragile H∞ control for a class of descriptor discrete interval systems with nonlinear disturbance was studied, where the nonlinear disturbance satisfies the Lipschitz condition. First of all, based on the theory of Lyapunov function, the robust H∞ control problem of the uncertain nonlinear descriptor system was described; Secondly, a sufficient condition for the existence of robust and non-fragile H∞ controller was given by linear matrix inequality approach, which guarantees that the resulting closed-loop descriptor system is admissible and satisfies a prescribed H∞ norm-bounded constrain for all admissible uncertainties. Meanwhile, the design method of the state feedback controller was proposed. Finally, numerical simulation results indicated the effectiveness of the developed method. References | Related Articles | Metrics

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Element yield prediction in ladle furnace based on feature construction Xu, Zhe (1); Mao, Zhi-Zhong (1) 2012, 33 (3):  310-313.  DOI: - Abstract ( 542 )   HTML   PDF (844KB) ( 838 )   Element yield prediction is a key and difficult problem of ladle furnace (LF) alloying. For improving its precision, main factors of element yield were determined by the mechanism analysis method. Because these factors cannot be readily available in production, factors were obtained indirectly by the feature construction method based on grammatical evolution (GE). Finally, the element yield prediction model was established using constructed features as inputs. Original GE algorithm was improved on the basis of the background issue. The improved method made full use of the existing features, and solved the problem that important data cannot be detected in the smelting process. The proposed method had been applied to element yield prediction of Mn and Si element of Q345B. Experimental results showed that the prediction accuracy could be improved effectively by utilizing the proposed method. References | Related Articles | Metrics

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Bidding evaluation behavior analysis of grouped multi-attribute reverse auction based on qualitative simulation Liu, Xu-Wang (1); Wang, Ding-Wei (1) 2012, 33 (3):  314-317+322.  DOI: - Abstract ( 525 )   HTML   PDF (407KB) ( 709 )   Reverse auction with multi-attributes is widely used for centralized procurements of large enterprises and government, and grouped multi-attribute is the most popular mechanism at present. Based on the current situation about bidding, the concept of grouped multi-attribute auction was proposed at first. Taking the bounded rationality of the bidding evaluation experts into consideration, some existing problems about the current mechanism were analyzed, and the relational graph of bidding evaluation behaviors about bidding experts was presented. Meanwhile, the qualitative model, which could influence the decision-making behavior of bidding evaluation experts, was established. The antagonistic feelings of two groups were studied by means of qualitative simulation (QSIM) and then the decision variable of different moments could be adjusted. Some significant results about the behavioral analysis have been obtained. And the simulation results indicated the effectiveness of this method. Because of the different benefit and responsibility, it is easy to bring about the accumulation of antagonistic feelings. As the difference increases, objectiveness becomes worse and worse. In the end, three improved suggestions were proposed. In further study, it will be a key point to improve and optimize the current mechanism of GMAA. References | Related Articles | Metrics

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Pulmonary nodules segmentation method based on improved random walker algorithm Yi, Yu-Feng (1); Gao, Li-Qun (1); Guo, Li (2) 2012, 33 (3):  318-322.  DOI: - Abstract ( 794 )   HTML   PDF (923KB) ( 628 )   The traditional methods for the segmentation and detection of pulmonary nodules could not segment pulmonary nodules accurately, and also could not separate the pulmonary nodules from blood vessels and chest wall. An improved random walker algorithm was proposed to solve the above problems. Firstly, according to the probability that calculated by Dirichlet boundary condition, the image will be divided into three parts: objective region, background region and uncertain region. Euclidean distance was used to calculate the difference between the nodes in the uncertain region and the seed, which can be used to label nodes in the uncertain region. Secondly, a parabola between two points algorithm (PBTP) for the second segmentation was proposed to achieve the final image segmentation. The experimental results demonstrated that the proposed algorithm segmented the pulmonary nodules more accurately than that of using the traditional methods, which greatly improved the accuracy of analysis and identification for computer-aided diagnosis (CAD) of pulmonary nodules. References | Related Articles | Metrics

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Robust H∞ control of a class of the disequilibrium economic systems and its application Li, Chun-Ji (1); Yu, Miao (1); Chen, Xiang-Yong (2) 2012, 33 (3):  323-326+331.  DOI: - Abstract ( 549 )   HTML   PDF (284KB) ( 503 )   Based on the disequilibrium theory, the disequilibrium cobweb model was studied, and the model was turned into the state-space equation. The robust controller was designed by using the robust H∞ control theory and the linear matrix inequality (LMI) technique. Based on the proposed method, some results could be obtained, such as, the impact of uncertainties on operation of the disequilibrium model could be restrained, stability of system evolution was guaranteed, and the operation of demand and supply of the goods came up to perfect state. Finally, taking the real estate development in Shenyang as the background, relevant statistics and simulation experiment were carried out and the H∞ control strategies were validated. The research results will have large significances on the theory and application of economic control system. References | Related Articles | Metrics

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Application of ant colony optimization in estimating motion vectors of ultrasound images Zhang, Yao-Nan (1); Yang, Le (1); Kang, Yan (1) 2012, 33 (3):  327-331.  DOI: - Abstract ( 546 )   HTML   PDF (1290KB) ( 665 )   In order to find out the robust motion vectors in ultrasound image sequence, a block matching method of the motion estimation under ant colony optimization (ACO) paradigm was proposed. The motion vector smoothness along sequence and the local similarity of the motion vectors are represented as pheromone values, and the sum of absolute difference (SAD) was used as heuristic value to drive ants to targets. The proposed method was implemented by using C++ and ITK and verified by experiments on real ultrasound images of carotid artery. Experimental results are fairly good, which indicates the feasibility of the proposed method. References | Related Articles | Metrics

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Automatic acquisition method of ontology instances from web tables Cha, Song-Il (1); Ma, Zong-Min (1); Jiao, Xiao-Long (1) 2012, 33 (3):  332-335.  DOI: - Abstract ( 637 )   HTML   PDF (330KB) ( 683 )   Information is mainly represented in tabular form in the modern society and scientific filed, so more and more attentions have been paid on how to extract ontology instances from the Web tables. In order to improve the accuracy of extracting ontology instances from the Web tables, an acquisition method of semantic class of words was proposed on the basis of semantic similarity. The method is based on SVM semantic similarity calculation method, which improves the accuracy of checking the semantic similarity, and overcomes the limitations of the previous analysis method of table structure by using syntactic similarity. Finally, according to the experimental results, the performance of this method is evaluated. Experimental results show that this method can effectively extract the ontology instances from Web tables. References | Related Articles | Metrics

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Dynamic spectrum assignment based on graph coloring in cognitive radio network Jia, Jie (1); Wang, Chuang (1); Zhang, Zhao-Yang (1); Chen, Jian (1) 2012, 33 (3):  336-339.  DOI: - Abstract ( 518 )   HTML   PDF (700KB) ( 817 )   Dynamic spectrum assignment scheme is an effective measure to solve the low utility of spectrum resources in cognitive radio networks. As to the "starvation" problem of cognitive users, a dynamic spectrum assignment algorithm based on graph coloring was proposed with the purpose of maximizing the system access ratio. The utility function was presented on the basis of graph coloring model, and by updating the available matrix, the allocation process could be implemented effectively. Simulation results demonstrated that the proposed algorithm can obtain a high system access ratio and achieve a good tradeoff between throughput and fairness, and it has much more superiority than the existing algorithms. References | Related Articles | Metrics

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Centrality measurement of internet network topology at AS-level Zhang, Jun (1); Zhao, Hai (1); Yang, Bo (1); Jia, Si-Yuan (1) 2012, 33 (3):  340-343.  DOI: - Abstract ( 655 )   HTML   PDF (964KB) ( 724 )   Centrality studies of complex network aim at finding out the centralization nodes in the network. The centrality measurement of the complex network can accurately and quickly find out the centralization nodes in a complex and large-scale network. Based on this, the network can be managed effectively. The problems of the centrality measurement of Internet at AS-level were studied. Based on the AS-level measuring data of CAIDA in Feb, 2011, the degree centrality, betweeness centrality and closeness centrality of Internet were analyzed and calculated, and the relationship among them was further explored. It was concluded that all the three measurements can find the centrality nodes in the network effectively. But the closeness centrality can reflect the global network more accuracy than the degree centrality and betweeness centrality. References | Related Articles | Metrics

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Design and implementation of prolonging life cycle of WSN in data collection Zhao, Hai (1); Shao, Shi-Liang (1); Zhu, Jian (1); Li, Da-Zhou (1) 2012, 33 (3):  344-347.  DOI: - Abstract ( 598 )   HTML   PDF (224KB) ( 551 )   The life cycle of WSN directly affects the application value in the Internet of things. According to the problem of how to prolong the life cycle of WSN, further study had been made on this issue. And ultimately the life cycle of WSN was effectively prolonged. Through the formation of simple and stable routing to provide the basis for robust communication path for the MAC layer, periodic sleep and wake-on-radio mechanism and FHPR algorithm were designed from the aspects of lowering power consumption and reducing the probability of packet collisions. The periodic sleep and wake-on-radio mechanism could allow the nodes in the ultra low-power state in a long term. The FHPR algorithm included frequency hopping table and the mechanism of packet regroupment, and the former could decrease the probability of data conflicts and the later could not only decrease the probability of data conflicts but also decrease the power consumption. Experimental results showed that the WSN constructed by the hardware platform can run stably and the life cycle has been prolonged obviously. References | Related Articles | Metrics

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A community discovery algorithm with variable resolution Chen, Dong-Ming (1); Xia, Fang-Zhao (1); Jia, Lu-Lu (1); Xu, Xiao-Wei (2) 2012, 33 (3):  348-351.  DOI: - Abstract ( 496 )   HTML   PDF (767KB) ( 620 )   Introducing some relational conceptions of complex network and community structure, a new community discovery algorithm based on core nodes detecting was proposed. Integrated feature value and gain function are employed in the new algorithm. Comprehensive eigenvalue which is related to the node degree and clustering coefficient is used to detect core nodes in community and the gain function judges when to get the best partition of community structure. The new algorithm is implemented with C++. Experimental results on the classic datasets demonstrate the feasibility and effectiveness of the algorithm. Further, the parameter can be tuned to get more detailed structure of the complex network than traditional algorithm which is very useful in many situations. References | Related Articles | Metrics

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CLAD algorithm of rolling force ratio load distribution on hot strip mill Li, Wei-Gang (1); Liu, Xiang-Hua (2) 2012, 33 (3):  352-356.  DOI: - Abstract ( 623 )   HTML   PDF (831KB) ( 788 )   An algorithm called change load ratio by adjusting draft (CLAD) was presented to achieve on-line optimal setting of roll force ratio draft scheduling of hot strip mill. The key point was to minimize the difference between current rolling force ratios and goal rolling force ratios by adjusting draft deviation of different finishing mills. According to the principle of rolling force ratio, non-linear equations were established. Combined with assumptions, the coefficient matrix was simplified to a diagonal matrix, and the iterative formula and convergence condition of the proposed new algorithm were derived by mathematical method. An empirical interpolation method was proposed to determine the initial value of draft scheduling and make the convergence speed of CLAD faster. Simulation experiments for typical rolled strips of BAOSTEEL showed that the new algorithm can be used in on-line pass schedule calculation with the advantages such as fast computing speed and excellent convergence performance. References | Related Articles | Metrics

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Research on parallel real time scheduling and memory allocation algorithm on multi-core platform Zhou, Ben-Hai (1); Qiao, Jian-Zhong (1); Lin, Shu-Kuan (1) 2012, 33 (3):  357-360+376.  DOI: - Abstract ( 607 )   HTML   PDF (672KB) ( 2757 )   With low power consumption and high performance characteristics, multi-core processors have occupied the main market. Aiming at parallel real time scheduling on multi-core platform, a scheduling algorithm combined with local and global EDF was proposed. The budgets, deadline partition, and task migration time were decided by the proposed CPU width reserved server. A memory allocation method was presented, which could manage the memory resources for parallel real time tasks effectively. Experimental results showed that the proposed new scheduling algorithm has a higher scheduling success rate. In addition, using the presented memory partition algorithm, real-time characteristics and stability of tasks were assured in memory competition situation. References | Related Articles | Metrics

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Fault-tolerant strategy for VSN based on statistical hypothesis testing Song, Xin (1); Wang, Cui-Rong (1) 2012, 33 (3):  361-364.  DOI: - Abstract ( 544 )   HTML   PDF (659KB) ( 615 )   In order to minimize energy dissipation and obtain higher fault sensor nodes recognition rate for deploying multi-target monitoring wireless sensor networks (WSN), a fault-tolerant strategy for virtual sensor networks (VSN) based on statistical hypothesis testing was proposed. On the cluster tree based VSN architecture, the fault occurring was judged by checking the matching degree between local data reading sequence and event statistical characteristics. The simulation results showed that before any node energy exhaustion, the multi-event monitoring produced less unicast messages and more multicast messages than single-event monitoring. In addition, the proposed strategy can maintain the fault identification rate and event region monitoring probability at the satisfactory level with increase of the sensor nodes fault probability. References | Related Articles | Metrics

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Investigation on hot corrosion resistance of a new directional solidification superalloy at 750C Huang, Yan (1); Wang, Lei (1); Liu, Yang (1); Wu, Jian-Tao (2) 2012, 33 (3):  365-368.  DOI: - Abstract ( 496 )   HTML   PDF (1305KB) ( 650 )   Hot corrosion resistance of a new directional solidification superalloy with a thin film of 75% Na2SO4+25% NaCl was investigated at 750°C. The phase compositions of corrosion products were identified by X-ray diffractometer (XRD) and the surface and the cross-sectional morphologies of the samples were observed by scanning electron microscope (SEM). The results showed that the hot corrosion rate is high. With the increasing of hot corrosion time and the thickening of hot corrosion layer, the hot corrosion rate is lower. The corrosion products can be divided into three layers. The loose external layer is mainly formed by TiO2 and Cr2O3, the intermediate layer is Cr-rich and the internal layer is mainly oxides of Al and Ti with the dot-like sulfide. The hot corrosion of the alloy is a coexist process of oxidation and vulcanization, accompanied by some volatility of corrosion products. During the process, the corrosion expands to the matrix of alloy and makes the corrosion layer thicken. References | Related Articles | Metrics

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Preparation and properties of complex silane conversion coating on galvanized steel sheet Wang, Lei (1); Liu, Chang-Sheng (1); Yu, Hai-Yun (1); An, Cheng-Qiang (2) 2012, 33 (3):  369-372.  DOI: - Abstract ( 557 )   HTML   PDF (1243KB) ( 615 )   A complex γ-APT and γ-GPT silane conversion coating was prepared on the galvanized steel sheet. The micro-morphology of the coating before and after passivation was observed by SEM. The corrosion resistance of the coating was tested by neutral salt spray test and electrochemistry test. The adhesion and flexibility of the coating were tested. The results showed that the surface of the complex silane conversion coating is completely consecutive and compact. The coating can endure the neutral salt spray test for 72 h. The complex silane coating can increase the corrosion resistance of galvanized steel sheet if the impedance value and the polarization resistance increase. The adhesion of the coating is grade 1. The coating flexibility is T-bend 1. References | Related Articles | Metrics

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Technology of Fe78Si9B13 amorphous magnetic powder core Tang, Jian (1); Lian, Fa-Zeng (1); Yu, Min (2); Fan, Xian-Yong (1) 2012, 33 (3):  373-376.  DOI: - Abstract ( 521 )   HTML   PDF (916KB) ( 572 )   The effects of powder preparation method, powder size and the addition amount of insulation agent on the performance of Fe78Si9B13 amorphous powder core were investigated. The results showed that the powders prepared by jet milling have fewer edges than those prepared by mechanical method. Most of the powders are roundel, which is more beneficial to insulation coating, so the properties are better. The powder grain size is greater, the magnetic powder core permeability is bigger, but the loss is bigger. As a result grain level deployment is needed. The best ratio is determined to be 70% of 75~100 μm powders, 10% of 61~75 μm powders, and 20% of 45~61 μm powders. The addition of insulation agent can improve the inherent resistance and reduce powder eddy loss, but too much insulation agent content will reduce the permeability. The optimal addition amount is 4% in this experiment. References | Related Articles | Metrics

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Synthesized conditions and electromagnetic properties of (La0.8Ho0.2)2/3 Ca1/3MnO3 manganite He, Ning (1); Li, Qing-Lun (1); Qi, Yang (1); Zhang, Cai-Bei (1) 2012, 33 (3):  377-380.  DOI: - Abstract ( 472 )   HTML   PDF (887KB) ( 599 )   The powdered (La0.8Ho0.2)2/3 Ca1/3MnO3 nanocrystalline was synthesized by sol-gel technique. Thermal analysis (TG-DTA) and X-ray diffraction were employed to investigate the chemical reaction process and the structural forming process. The effects of the mole ratio of citric acid to total metal cation content, calcination temperature and time on the formation of perovskite structure were investigated. Structural analysis showed that the powdered phase remains perovskite structure and becomes perfect above 680°C. The resistance measurement was carried out with a conventional four-probe method, and the M-T curves of samples were monitored by the superconducting quantum interference device (SQUID) operated at 0.1 T magnetic field. The results showed obviously changes in the phase transition owing to partial replacement of La by Ho element in La2/3Ca1/3MnO3. References | Related Articles | Metrics

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Semi-continuous casting of semisolid billet of AZ91D magnesium alloy by vibrating wavelike sloping plate process Guan, Ren-Guo (1); Zhao, Zhan-Yong (1); Dai, Chun-Guang (1); Liu, Chun-Ming (1) 2012, 33 (3):  381-384.  DOI: - Abstract ( 548 )   HTML   PDF (1742KB) ( 636 )   A self-made vibrating wavelike sloping plate device and a semi-continuous casting machine were combined. The semisolid billet of AZ91D magnesium alloy was prepared by the proposed process, and the effects of the different process conditions on the microstructures were investigated. The results showed that in a certain scope, the shearing and cooling time is enlarged with the increasing of the plate length, which leads to the grain refinement. Vibration can improve the nucleation rate and obviously refine the microstructure. At the lower casting speed, the nucleation rate in the crystallizer is higher, which causes the finer microstructure in the billet. Under the conditions that the casting temperature is 680°C, the sloping plate length is 400 mm and the casting speed is 100 mm/min, the semisolid billet of AZ91D magnesium alloy with fine microstructure is prepared by the semi-continuous casting process. After re-melting, the fine semisolid microstructure is obtained. References | Related Articles | Metrics

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Effect of ultrasonic vibration parameters on degassing of Mg-Ca alloy Jia, Zheng (1); Le, Qi-Chi (1); Zhang, Zhi-Qiang (1); Cui, Jian-Zhong (1) 2012, 33 (3):  385-388+396.  DOI: - Abstract ( 479 )   HTML   PDF (2020KB) ( 520 )   The effect of different vibration parameters, including ultrasonic power and duration time, on the degassing of molten Mg-Ca alloy was investigated by using ultrasonic field. The results showed that both the ultrasonic power and the duration time have significant effects on the degassing effect. Low ultrasonic power and short or long duration time have weak effect on the degassing. The degassing effect is related with the ultrasonic cavitation, and the optimum degassing effect only occurs in the developing-developed stage of the cavitation. In this experimental condition, when the ultrasonic power and the duration are 150 W and 120 s respectively, there has the optimum degassing effect and the density of ingot reaches the maximum value. The ultrasound refines effectively the solidification structure of Mg-Ca ingot at the same time. References | Related Articles | Metrics

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Optimum study of billet space in walking beam furnace Li, Guo-Jun (1); Liu, Xiao-Ting (1); Yi, Zhi (1); Chen, Hai-Geng (1) 2012, 33 (3):  389-391+430.  DOI: - Abstract ( 559 )   HTML   PDF (699KB) ( 636 )   The reasonable billet space in walking beam furnace is of great significance to improve the productivity of the furnace. The related expressions of billet side heat flux were derived by using a radiation network, and the effect of billet space on heat-up time and furnace productivity were analyzed. What's more, the optimum space between billets was gotten using the extremum of relative productivity computed expression, which had been derived. Compared with the references, this study gets rid of the assume that the billet surface is bold and the expressions worked out are more general used, which has the important reference value to optimize the arrangement of billet and non-ferrous metal billet in the walking beam furnace. References | Related Articles | Metrics

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Mathematical regression of exponential wide band model and its application Yi, Zhi (1); Liu, Xiao-Ting (1); Zhang, Wei-Jun (1); Chen, Hai-Geng (1) 2012, 33 (3):  392-396.  DOI: - Abstract ( 525 )   HTML   PDF (917KB) ( 543 )   To solve radiative heat transfer problems, the determination of gas radiative properties can be accurately obtained by the exponential wide band model(EWBM), but it is unfit to online engineering application owing to its complex computational process and slow computation speed. Based on the analysis of EWBM results, the computational temperature range was determined by the temperature of furnace gas and the furnace internal surface. The parameters for each band were regressed to the functional expressions changed with temperature and pressure, which significantly simplifies the solving process and improves the computational efficiency on the premise of accuracy guarantee. References | Related Articles | Metrics

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Numerical simulations of complex behaviors for the funnel shape mold with new type EMBR Tian, Xi-Yan (1); Li, Ben-Wen (1); Zou, Fang (2); He, Ji-Cheng (1) 2012, 33 (3):  397-400+443.  DOI: - Abstract ( 509 )   HTML   PDF (1318KB) ( 512 )   A new type electromagnetic brake(EMBR) equipment was specially designed for the funnel shape mold and 3D models were built. Numerical simulations of the magnetic fields produced by the new type EMBR equipment were done with ANSYS, and the magnetic field data results were obtained. Subsequently, the magnetic field was coupled with the turbulent flow, the heat transfer and the solidification simultaneously by FLUENT. In the treatment of the magnetic field data, the linear interpolation by FORTRAN was adopted. The casting speed of 5.5 m/min with the depth of the submerged entry nozzle (SEN) of 300?mm was considered. A series of simulations were carried out to investigate the effects of the height of the magnet and the magnetomotive force on both the flow and the temperature fields. The results showed that due to the EMBR effects, the magnet height of 250 mm is much better than that of 300 mm. As for the parameters of the flow field in present work, the magnetomotive force of 8 kA·n is rational; the higher magnetomotive force may cost more unnecessary electrical energy. References | Related Articles | Metrics

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Preparation of Al2O3 powders by spray pyrolysis deposition Zhao, Ai-Chun (1); Zhang, Ting-An (1); Lü, Guo-Zhi (1); Dou, Zhi-He (1) 2012, 33 (3):  401-404.  DOI: - Abstract ( 770 )   HTML   PDF (1356KB) ( 828 )   High purity Al2O3 powders were deposited successfully by the spray pyrolysis method using AlCl3·6H2O as raw material. The phase composition and the micro-morphology of pyrolysis products were studied by X-ray diffraction (XRD) and SEM. Specific surface area was also analyzed by specific surface area analyzer. The thermodynamics results showed that the main pyrolysis reaction happens in the range of 800~2200 K and increasing the reaction temperature is advantageous to the reaction. The pyrolysis temperature is 800°C for AlCl3 by DSC-TGA analysis. The experimental results indicated that the optimum conditions are as follows: the mass fraction of AlCl3 solution is 15%; the pyrolysis time is 20 min in the range of 750~850°C. Meanwhile, the pyrolysis products meet the demands of electronic aluminum. References | Related Articles | Metrics

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Decolorization of methyl orange wastewater by UV-irradiated TiO2 nanotube arrays Shang, Ke-Feng (1); Xue, Xiang-Xin (1); Li, Ming-Tao (1) 2012, 33 (3):  405-408.  DOI: - Abstract ( 454 )   HTML   PDF (1654KB) ( 613 )   TiO2 nanotube arrays were prepared by potentiostatic anodization of pure Ti foils in an approximately neutral solution. The effect of anode voltage, anodization time and the mass concentration of the fluorion in electrolyte on the micromorphology of TiO2 nanotube arrays was studied. The results showed that the pore diameters and the wall thickness of TiO2 nanotubes ranges from 30 nm to 50 nm and 20 nm to 25 nm, respectively. The TiO2 nanotube arrays film is amorphous before annealing, and then turns into anatase and rutile after annealing at 550°C, in which anatase is dominant. Decolorization experiments of methyl orange(MO) wastewater indicated that the fabricating conditions also influence the decolorization rate of MO, and the higher photocatalytic decolorization rate is obtained by the regular TiO2 nanotube array film. Comparing with direct photolysis, the photocatalysis of TiO2 nanotubes can increase the decolorization rate of MO by 40%. References | Related Articles | Metrics

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Visual design of a straightening force model for tubes and bars straightened by equal curvature Zhang, Zi-Qian (1); Zhang, Bai-Sen (1); Yang, Hui-Lin (1); Yan, Yun-Hui (1) 2012, 33 (3):  409-413.  DOI: - Abstract ( 571 )   HTML   PDF (1055KB) ( 950 )   Since there is no accurate mathematical model, the straightening force is usually determined by worker's experience and repeated experiments when tubes and bars are straightened by the rolls with equal curvature. Aiming at this problem, a straightening force model was established on the basis of the principle of mechanical equivalence, and then the equal curvature straightening process was visually simulated by the ANSYS/LS-DYNA. The results confirmed by local experiments is shown to be valid and receivable. The key parameters under different conditions of the model were determined by visual simulations, which may make the model applicable in different situations. References | Related Articles | Metrics

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Effect of high speed point grinding parameters on temperature field and surface hardness Gong, Ya-Dong (1); Cao, Zhen-Xuan (1); Liu, Yue-Ming (1); Cheng, Jun (1) 2012, 33 (3):  414-417.  DOI: - Abstract ( 507 )   HTML   PDF (1075KB) ( 613 )   The technology of high speed point grinding has been widely used in the equipment manufacturing industry. The real temperature field distribution and the highest temperature could be simulated with loading the moving heat source by considering the effect of the swivel angle α on the heat flow transferred to work-surface, and the thickness of affected layer at the subsurface was also analyzed. The orthogonal test for high speed point grinding with different grinding parameters was designed to get the real surface hardness, which could verify the work-surface temperature field simulation and acquire the sensitivity parameters for surface hardness. The results show that the temperature rise is reduced by introducing swivel angle α, and the cutting depth is the main factor for temperature rise in grinding area; and with the temperature heaving and achieving a certain value, the component's hardening layer will be changed and the hardening effect will be destroyed. References | Related Articles | Metrics

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Damage detection of the honeycomb sandwich panel based on vibration shape data Zhang, Ying-Jie (1); Yan, Yun-Hui (1); Li, Yong-Qiang (2); He, Yong-Liang (2) 2012, 33 (3):  418-421+452.  DOI: - Abstract ( 480 )   HTML   PDF (2587KB) ( 574 )   An aluminous honeycomb sandwich panel with some structural damages was selected as the objective in this study. The panel was simply supported along four edges and its vibration shape data was collected through modal experiment with a hammering method. The damages with different degrees at different positions of the honeycomb sandwich panel were identified by three identification methods, i.e., the modal difference of vibration shape, the curvature mode and the Gaussian curvature mode, respectively. It is found that the modal difference of vibration shape at the damage location is obvious when the honeycomb sandwich panel has some structural damages. This indicates that the damage location can be accurately identified by using the difference of vibration shape. Furthermore, the damage degree can be identified according to the difference at the damage location after the damage location is defined. References | Related Articles | Metrics

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Numerical simulation of the vacuum spray jet flow based on fluent analysis Li, Jian-Chang (1); Li, Hong-Yu (1); Han, Yu (1); Ba, De-Chun (1) 2012, 33 (3):  422-425.  DOI: - Abstract ( 1916 )   HTML   PDF (1561KB) ( 1926 )   This paper investigated the velocity and turbulence distribution of the cone nozzle jet flow field spraying into a vacuum chamber under different nozzle diameters and injection pressures. The simulations were carried out by using the Fluent software based on the volume of fluid method, the standard k-Ε turbulence model and the PISO (pressure implicit with splitting of operators) arithmetic. The results show that the jet flow and velocity gradient increase with increasing nozzle diameter, and it is helpful to improve jet spray quality with size uniform distribution after jet diffusion and drop breakup. When the nozzle diameter is constant, the jet turbulence intensity distribution achieves the optimum condition within 10~15 MPa, and the flow field is better than that under any other pressures. Compared with chloroform and carbon tetrachloride solvents, acetone shows better flow distribution and atmospheric effect if neglecting the solubility of the polymer materials. References | Related Articles | Metrics

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Bucket target recognition method of excavator robot based on invariant moments and improved BP neural network Wang, Fu-Bin (1); Liu, Jie (1); Chen, Zhi-Kun (2); Wang, Jing-Bo (2) 2012, 33 (3):  426-430.  DOI: - Abstract ( 644 )   HTML   PDF (867KB) ( 614 )   When tracking and identifying the bucket target of excavator robot by using visual information, there exist rotation, translation and zoom situations for the bucket images collected in real time. To improve the identifying ability of the bucket target, a recognition method of bucket target was proposed based on invariant moments and BP neural network. The method extacted seven moment characteristic quantities of bucket image with invariant performance against translation, rotation and zoom. They can act as the training and testing samples for improved BP neural network after being normalized. Using the trained neural network to identify bucket target, the simulation result shows that this method has high recognition ability. References | Related Articles | Metrics

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Effect of siderite on flotation separation of martite and quartz Li, Li-Xia (1); Yin, Wan-Zhong (1); Wang, Yu-Bin (2); Tao, Shi-Jie (3) 2012, 33 (3):  431-434.  DOI: - Abstract ( 532 )   HTML   PDF (1426KB) ( 718 )   It has been confirmed that the appearance of iron carbonate may seriously deteriorate the floatation indexes. The effect of siderite contents on flotation of martite and quartz was investigated with three flotation systems. The results show that, with mixing the siderite into martite and quartz, the flotation indexes decrease in the dodecylamine and sodium oleate systems while the concentrate grade increases in sodium dodecyl sulfate system. Thus, the influence of the fine particle siderite must be eliminated in order to achieve effective separation of iron ore containing carbonates. References | Related Articles | Metrics

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Quality monitoring of coal slime water and application of soft-sensing technique Zhang, Zhi-Jun (1); Liu, Jiong-Tian (1); Wang, Yong-Tian (2); Feng, Li (2) 2012, 33 (3):  435-438.  DOI: - Abstract ( 526 )   HTML   PDF (522KB) ( 525 )   In order to regulate the water hardness of coal slime water to the benefit of both settling and flotation, realization of water hardness online monitoring is a basic guarantee. Since the technique of water hardness monitoring has not been industrialized, a soft-sensing technique which uses electrical conductivity as the auxiliary variable was proposed. Laboratory simulation and industrial scene monitoring tests were performed, and the results show that there exists linear correlation between the electrical conductivity and the water hardness, and the squares of linear correlation coefficient are 0.9796 and 0.9537, respectively. A soft-sensing model between the water hardness and the electrical conductivity were developed, through which the data of electrical conductivity can be processed and converted so as to realize online monitoring of the hardness of coal slime water. References | Related Articles | Metrics

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Simulation on ground source heat pump system combined with seasonal air thermal energy storage Han, Zong-Wei (1); Ding, Hui-Ting (1); Li, Xian-Ting (2); Shi, Yong-Zheng (3) 2012, 33 (3):  439-443.  DOI: - Abstract ( 464 )   HTML   PDF (1369KB) ( 633 )   Regarding the problem of ground heat balance in cold area, a ground source heat pump system which can seasonally accumulate environmental air thermal energy was presented. The components and operation modes of the system were introduced, and the control strategy of system operation was determined through setting up the mathematic model of each system section. Based on the mathematic model and control strategy, the transient numerical simulation was carried out for an office building in Harbin. The simulation results show that the ground source heat pump system can retain thermal balance of the soil temperature field over an one year cycle. The average coefficient of performance was calculated to be 2.44. Compared with that of the coal-fired heating and air conditioning, the system energy-saving rate is 22.3%. References | Related Articles | Metrics

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Study of the soil weathering degree of the Liao River Basin based on CIA index Qi, Wei (1); Fu, Jian-Fei (1); Wang, En-De (1); Men, Ye-Kai (1) 2012, 33 (3):  444-447.  DOI: - Abstract ( 780 )   HTML   PDF (1765KB) ( 1796 )   The soil weathering degree of the Liao River Basin was studied on the basis of CIA index. It is shown that the soil weathering degree is generally very low in the Liao River Basin and there is no much difference between the deep and surface layers of the soil. The element spatial distribution of the deep and surface layers of the soil is U-type. The element content in the east is higher than that of the west, while it shows the lowest in the center. The weathering degree of the paddy soil and black soil is the highest in all types of soil, on the contrary, the aeolian sandy soil and fluvo-aquic soil show the lowest degree. In the case of geomorphologic one, the CIA value of the plain area is the highest with soil weathering degree higher than that of the mountain hilly area, the hilly and low mountain areas. References | Related Articles | Metrics

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Study on the optimal expert allocation strategies in team-based organizations Huang, Xun-Jiang (1) 2012, 33 (3):  448-452.  DOI: - Abstract ( 419 )   HTML   PDF (974KB) ( 547 )   Given that different expert allocation strategies in team-based organizations tend to result in varied knowledge diffusion performances, this study takes the perspective of structural dimensionality. It constructs a knowledge diffusion model of team-based organizations based on the complex network theory and explores the influences of different expert allocation strategies on knowledge diffusion performances by applying the simulation techniques. The major findings for this study are as follows: team-based organizations with the same network density and size exhibit a better knowledge diffusion performance than those traditional organizations. Experts exhibit the best knowledge diffusion performance in the even distribution strategies among teams. The disseminative capacity of the same advancement range turns out a better knowledge diffusion performance than the absorptive capacity. Thus, it could be concluded that confined by the equivalent resources, an organization should give priority to enhancing its members' disseminative capacity. References | Related Articles | Metrics

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Research on contractor selection based on project partnership Wang, Shun (1); Ma, Qin-Hai (1); Feng, Zhuo (2) 2012, 33 (3):  453-456.  DOI: - Abstract ( 494 )   HTML   PDF (144KB) ( 942 )   In view of the fact that with a more traditional contractor selection model it is rather difficult to pick out the right contractors based on project partnership, although both clients and contractors might benefit through cooperation in the construction industry, a factor analysis is employed to analyze the 16 variables affecting the successful project cooperation in the construction industry. It then puts forward a basic framework of contractor selection based on project partnership and interprets the criteria for contractor selection from a new perspective. Finally, the paper points out that clients should attach great importance to the following four aspects: willingness to cooperate, agility, ability to cooperate and capability of procurement, which could provide reference for them to select appropriate contractors at the procurement stage. References | Related Articles | Metrics