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15 November 2012, Volume 33 Issue 11 Previous Issue    Next Issue
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Nonlinear adaptive sliding mode control for TCP networks Ye, Cheng-Yin (1); Jing, Yuan-Wei (1) 2012, 33 (11):  1521-1524.  DOI: - Abstract ( 469 )   HTML   PDF (502KB) ( 617 )   For the TCP network in the presence of highly variable network parameters and UDP flows, two nonlinear adaptive sliding mode control algorithms were presented. Because the upper bound of the system uncertainties could not easily be obtained, an adaptive sliding mode controller was presented based on the upper bound of the system uncertainties. However, the chattering could not be eliminated effectively with this algorithm because of the using of sign function. So, an adaptive sliding mode controller was presented to directly adapt the system uncertainties. Simulation results demonstrated that the adaptive sliding mode controller for the system uncertainties is superior to that for the upper bound, and the adaptive sliding mode controller for the upper bound is superior to PI controller. References | Related Articles | Metrics

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Stability analysis for singular system based on singular state observer Xing, Wei (1); Li, Ning (1); Lu, Chun-Hong (1) 2012, 33 (11):  1525-1528.  DOI: - Abstract ( 453 )   HTML   PDF (1243KB) ( 504 )   In the condition of sensor adopted time driven and controller and actuator adopted event driven assuming that the transfer delay is shorter than the sampling period and the lose rate of date packet transfer is given, the singular networked control system was modeled as an asynchronous dynamical system for a class of the regular, impulsive-free and impulsive observable singular networked control systems with delay and date packet dropout. At the same time, state observer keeps structural of the systems, so based on the state feedback controller of the original system, the stability conditions of the system were proved with the Lyapunov function and LMI method. At last, a simulation example revealed the effectiveness of the proposed method. References | Related Articles | Metrics

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Sliding sector-based variable structure control for Markov jump system Shen, Mou-Quan (1); Zheng, Bo-Chao (1); Wang, Ming-Shun (1) 2012, 33 (11):  1529-1532.  DOI: - Abstract ( 627 )   HTML   PDF (1437KB) ( 700 )   For a class of continuous-time Markov jump linear uncertain systems, a variable structure control strategy was design to achieve quadratic stability based on sliding sector methods. The definition of the sliding sector for Markov jump system was firstly presented, and then based on linear matrix inequality technique, the design method of the sliding sector for Markov jump linear system was given. Finally, the variable structure control strategy for Markov jump linear system was developed. It was proved that quadratic stability is obtained by using the proposed method, and result of a numerical simulation example indicated the efficiency of the developed stability. References | Related Articles | Metrics

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Modeling and optimization of cobalt oxalate particle size distribution in hydrometallurgy synthesis process Chang, Yu-Qing (1); Liang, Qian (2); Wang, Shu (1); Zhang, Shu-Ning (2) 2012, 33 (11):  1533-1537.  DOI: - Abstract ( 507 )   HTML   PDF (1524KB) ( 767 )   A control strategy based on real-coding adaptive genetic algorithm(AGA) was developed and applied to the optimal control of cobalt oxalate synthesis. Based on the least squares support vector machine with the dynamic mechanism model of the synthesis process, a hybrid modeling method of the distribution was used to predict the particle size distribution(PSD). On this basis, the objective function and constraints of the PSD optimization model were established. The real-coding AGA was developed to solve the optimization problem. Simulation results showed that the method proposed can achieve a higher yield. Therefore, the optimization of cobalt oxalate PSD is of great importance to the industrial production of cobalt oxalate and to promote the development of cemented carbide industry. References | Related Articles | Metrics

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Estimate of kinetics reaction rate for gold cyanidation leaching process Zhang, Jun (1); Mao, Zhi-Zhong (1); Jia, Run-Da (1) 2012, 33 (11):  1538-1541.  DOI: - Abstract ( 531 )   HTML   PDF (1153KB) ( 676 )   In the gold cyanidation leaching process, the immeasurability of kinetic reaction rate brings difficulties of the model identification, and estimating rate by concentration data is an ill-posed inverse problem. The noise in the measured concentration data will be amplified arbitrarily leading to unreliable results. The Tikhonov regularization method was used to estimate the kinetics reaction rate of gold and cyanide ion only using concentration, flux data and mass conservation equations without establishing any kinetics reaction model, which reduces the propagation of errors in the measured data effectively. The experimental results showed that the proposed method is easier to implement and can better track the kinetics reaction rate trends, and the method can also restrain the amplification of noise. By comparison with the methods of finite difference and smooth filter, it has better estimate performance than other common methods. References | Related Articles | Metrics

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Sliding mode control for hydraulic looper uncertain system in hot strip mills Wang, Hong-Wei (1); Wang, Su-Xin (1); Yu, Chi (1); Gong, Ming-Long (1) 2012, 33 (11):  1542-1546.  DOI: - Abstract ( 478 )   HTML   PDF (2178KB) ( 612 )   For a class of multi-input multi-output (MIMO) hydraulic looper uncertain system in hot strip mills, a sliding mode controller was designed. First, the original uncertain system was turned into a standard model based on a particular linear transformation. Then, the sliding mode surface function was obtained by applying Lyapunov function approach and the linear matrix inequality (LMI) technique, and a novel sliding mode control (SMC) strategy was proposed and theoretically proved based on the sliding mode reaching conditions. Simulation results demonstrated that the proposed algorithm get much better control performance, and make the looper system come to a stable equilibrium state quickly. What's more, the control accuracy for looper system of hot strip finishing mills was also improved. This kind of control action has robust performance for looper and tension, which is suitable for the complex looper systems. References | Related Articles | Metrics

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River detection in remote sensing image based on multi-feature fusion Yu, Xiao-Sheng (1); Wu, Cheng-Dong (1); Chen, Dong-Yue (1); Tian, Zi-Heng (1) 2012, 33 (11):  1547-1550.  DOI: - Abstract ( 622 )   HTML   PDF (1804KB) ( 895 )   Due to the difficulties to exactly detect the similar rivers, a novel river detection algorithm was proposed based on multi-feature fusion of the remote sensing image. Firstly, the local entropy features, the texture features and corner information features of the simple images were extracted as the feature vectors of the support vector machine (SVM) in order to obtain the decision function. Then the decision function was employed to perform the coarse detection of rivers in tested images. Finally, in order to obtain the complete rivers, the geodesic active contour model was used, which was combined with the results of the coarse detection of rivers. Experimental results demonstrated the proposed algorithm has good performance in the location and connection of rivers, and the rivers can be detected accurately without the background interference. References | Related Articles | Metrics

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Entity relevance based on the area subgraph Chen, Chen (1); Liu, Hui-Lin (1); Xin, Jun-Chang (1); Wang, Guo-Ren (1) 2012, 33 (11):  1551-1554.  DOI: - Abstract ( 413 )   HTML   PDF (581KB) ( 653 )   A new method for the measurement of entity relevance was proposed on the basis of entity relationship graph. By defining the area graph, the semantic of each entity was well presented. To speed up the calculation of the similarity between two area subgraphs, the area subgraphs were first converted into semantic trees. Then the kernel function was used to calculate the similarity by counting the number of shared subtrees. At last, the proposed methods were evaluated on the basis of the experimental results. The experimental results proved that the proposed method had a good performance in both accuracy and efficiency. References | Related Articles | Metrics

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Lifetime maximization based on cross-layer design for wireless sensor networks Shan, Li-Qun (1); Wang, Jin-Kuan (1); Liu, Zhi-Gang (1); Du, Rui-Yan (1) 2012, 33 (11):  1555-1558.  DOI: - Abstract ( 549 )   HTML   PDF (1760KB) ( 557 )   The lifetime maximization in wireless sensor networks (WSNs) was investigated. Network traffic and power consumption were analyzed, and an optimization model was proposed, which integrated power control and data aggregation. A decomposition algorithm was presented to solve the model by decomposing the model into sub-problems. The optimal transmission power, transmission rate and routing selection solution could be obtained via the subgradient. The simulation results showed that the data traffic can be reduced and energy consumption can be balanced on the basis of the proposed cross-layer design algorithm, and the network lifetime can be prolonged effectively. References | Related Articles | Metrics

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Null broadening and sidelobe control method based on multi-parametric quadratic programming Liu, Fu-Lai (1); Chen, Ping-Ping (2); Wang, Jin-Kuan (1); Peng, Lu (2) 2012, 33 (11):  1559-1562.  DOI: - Abstract ( 615 )   HTML   PDF (406KB) ( 908 )   The direction-of-arrival of jammer can be aimed at automatically based on the adaptive beamforming algorithm. However, it will be resulted in the mismatch between adaptive weight and data due to the perturbation of the interference location. Besides, the traditional beamformers may have unacceptably high sidelobes when few samples are available. To solve the above problems, an effective approach was presented to broaden null and control sidelobes. Firstly, a tapered covariance matrix was constructed to modify the measured covariance matrix. Secondly, multiple quadratic inequality constraints outside the mainlobe beampattern area were used to control sidelobes. Thirdly, the resulting optimization problem was formulated as a multi-parametric quadratic programming (mp-QP) problem. Simulation results were presented to verify the efficiency of the proposed algorithm, such as it can achieve higher array gain and the optimal weight vector can be easily obtained by real-valued computation. References | Related Articles | Metrics

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Service-oriented topology control algorithm for space information network Ye, Ning (1); Wang, Qian-Qiu (1); Li, Sheng-Li (2) 2012, 33 (11):  1563-1566.  DOI: - Abstract ( 489 )   HTML   PDF (1557KB) ( 555 )   The large scale and increasing kinds of service in space information networks were considered to propose a service-oriented topology control algorithm. According to demands of existing service, the topology of network was divided into several logical sub-topologies. The communication pattern was taken as an example, and the minimum-weight-based approach was adopted to construct topologies which could meet the requirements of all-to-one and one-to-all communication. The weight of link was calculated using the proposed algorithm according to the requirements of bandwidth, delay, delay jitter and reliability. After that, a minimum weight outconnected subgraph of the original topology was constructed, and the ultimate topology was created by reversing the direction of each link. The simulation results indicated that the redundant links could be removed effectively using the proposed algorithm, and the effectiveness of data transmission was improved. The fault tolerance of the network was ensured and the proposed algorithm could also be adapted to the multiple application requirement of space information networks. References | Related Articles | Metrics

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Partition algorithm based on the size of sub-community and geography Xu, Jiu-Qiang (1); Cui, Xing-Bing (1); Yu, Qun (1); Zhao, Hai (1) 2012, 33 (11):  1567-1570.  DOI: - Abstract ( 487 )   HTML   PDF (1135KB) ( 669 )   A new definition for the size of community was proposed based on the CNM algorithm, which was to solve the problem of excessive size of community exist in the past algorithm for detecting community. The new partition algorithm was called CLCNM. The results of community partition showed that the improved algorithm was superior to the CNM algorithm on the number of community and modules. On this basis, the relation between community partition and geography was studied, and a conception of the similarity of address prefix was proposed, which indicated that the greater similarity, the more obvious effect of relation between community and geography. The results of community partition by CLCNM showed that the communities of IPv6 topology had an obvious effect of geography, that was the sub-group node located in adjacent geographical location. This conclusion can provide advice to the re-deployment of network topology. References | Related Articles | Metrics

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Application of width micro-reducing rolling technique in plate width control Ding, Jing-Guo (1); Qu, Li-Li (2); Hu, Xian-Lei (1); Liu, Xiang-Hua (1) 2012, 33 (11):  1571-1573+1590.  DOI: - Abstract ( 411 )   HTML   PDF (2380KB) ( 701 )   In plate width control process, a micro-reducing rolling technique was put forward to improve the square degree on different broadening ratio of products. The width alteration rules on different broadening ratio as well as the relationship between lateral flow factors and broadening coefficient were analyzed. The width form functions were built, each point dog-bone recovery broadening along length direction was calculated, and the reducing width rolling curve with edger roll gradual gap based on this recovery broadening was obtained. Practical applications showed that the method proposed is available to improve greatly the product rolling yields and worthy to apply to plate rolling. References | Related Articles | Metrics

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Anti-crack ability and impact fracture of X100 pipeline steel Zhou, Ping (1); Huang, Shao-Wen (2); Du, Lin-Xiu (1); Liu, Xiang-Hua (1) 2012, 33 (11):  1574-1577.  DOI: - Abstract ( 557 )   HTML   PDF (2380KB) ( 695 )   Dynamic Charpy impact test of the X100 pipeline steel with different final cooling temperature and testing temperature was conducted. The fracture morphology and microstructure were observed. The results showed that when the final cooling temperature is 400°C, the crack formation and propagation energy maintains at a high level, anti-crack ability is good, a few layer phenomenon occurs only at -60°C. When the final cooling temperature is 520°C, the crack formation and propagation energies are reduced with the decreasing of testing temperature, the anti-crack ability decrease too, and the layer phenomenon at impact fracture is aggravated gradually. The maximal shock load is increases linearly with the testing temperature decreases. The fine and uniform microstructure and the tiny separation phases at the grain boundaries and bainitic laths are favorable to the impact toughness. References | Related Articles | Metrics

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Microstructures and properties of 780 MPa engineering machinery steel under ultra fast cooling process Yi, Hai-Long (1); Xu, Yang (1); Xiao, Ai-Da (2); Liu, Zhen-Yu (1) 2012, 33 (11):  1578-1581.  DOI: - Abstract ( 702 )   HTML   PDF (2270KB) ( 691 )   A mass trial was carried out for a 780 MPa engineering machinery steel and the microstructures and properties of steel were investigated. The controlled rolling, ultra-fast cooling and laminar cooling process were used based on the optimized compositions of steel, and good microstructures and mechanical properties were obtained. The results showed that ultra fast cooling plus laminar cooling process is used after the finish rolling, and the outlet temperature of ultra fast cooling and coiling temperature are controlled at 650°C and 570°C, respectively. The yield and tensile strengths of steels are higher than 685MPa and 785 MPa, respectively, and good impact resistance, formability and weldability are obtained. The microstructures of steels are composed with ferrite and a litlle of pearlite. A large number of (Nb, Ti) (C, N) precipitates are observed with size less than 10 nm dispersed in the ferrite matrix, and these fine precipitates increase the strength of steel effectively. References | Related Articles | Metrics

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Continuous cooling temperature field for plate after rolling during fully developed regime by variational method Zhang, Shun-Hu (1); Zhao, De-Wen (1); Gao, Cai-Ru (1); Wang, Yan (1) 2012, 33 (11):  1582-1585.  DOI: - Abstract ( 494 )   HTML   PDF (1979KB) ( 619 )   Based on Ritz transient temperature field functional, the variational solution of temperature field for the plate after rolling during fully developed regime was first obtained by variational method. Its distribution was a parabola. The comparison between the variational results and those analytical results by the separation variable method as well as the numerical results by finite difference method showed that the results obtained by variational method have higher forecast precision with the analytical and numerical results, and the maximum error among them is less than 6°C. Besides, the expressions of the average temperature, average cooling rate, occurrence location of the average temperature, the temperature difference between plate surface and centre along thick direction, and the time required for cooling to a certain margin of error are also given. A test proves the reliability of variational function. References | Related Articles | Metrics

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Study on roll elastic deformation asymmetrical 4-high mill stiffness Gong, Dian-Yao (1); Xu, Jian-Zhong (1); Yuan, Fang-Cheng (2) 2012, 33 (11):  1586-1590.  DOI: - Abstract ( 435 )   HTML   PDF (1736KB) ( 717 )   According to the real condition of different stiffness between the driving side and operating side of some stand mill in a hot strip factory, a calculation module was developed using influence coefficient method based on dual cantilever beam theory to research the regularity of roll elastic deformation under the condition of asymmetrical stiffness. Force analysis of 4-high mill under asymmetric condition was demonstrated, the roll and work piece were discretized following the principle of influence coefficient method, and the key influence functions were presented. The module was used to calculate and analyze the elastic deflection of work roll, the bruise between work roll and backup roll, the bruise between work roll and work piece, the rolling force and roll load distribution in lateral direction between work roll and backup roll with different stiffness differences. The profile of the rolled work piece with different stiffness differences were calculated and analyzed. References | Related Articles | Metrics

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DLA model for frost crystal growth on hydrophobic cold surface Lei, Hong (1); Qiao, Na (1); Geng, Dian-Qiao (1); Zhang, Hong-Wei (1) 2012, 33 (11):  1591-1594.  DOI: - Abstract ( 464 )   HTML   PDF (934KB) ( 765 )   On the base of DLA (Diffusion-Limited Aggregation) model, a two-dimensional mathematical model was developed to describe the frost crystal growth on the hydrophobic cold surface in order to have a deep insight into the dynamic growth process of frost crystal. In this model, the surfaces with different ice beads were used to simulate the different hydrophobic surfaces, and the metal surface was covered with ice beads. The movement of the water-vapor molecule was described by the particle's movement in the grid-nodes, and the probability for the particle to move at each direction was the same. Numerical results showed that the predicted frost dynamic growth process of frost crystal conforms to the existed experimental result. The predicted dendritic frost crystal has the fractal structure, and its fractal dimension is between 1.44 and 1.78. Such results are in good agreement with the experimental data. The frost crystal grows up slowly and distributes sparsely on the hydrophobic cold surface, and the frost formation on the cold surface with bad hydrophobic coating is similar to that on the metal surface. References | Related Articles | Metrics

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Preparation of SiO2 xerogel and investigation of its calcining characteristic Han, Lu (1); Yuan, Lei (1); Zeng, Shao-Wu (1); Yu, Jing-Kun (1) 2012, 33 (11):  1595-1598.  DOI: - Abstract ( 497 )   HTML   PDF (1957KB) ( 904 )   SiO2 xerogel was prepared by sol-gel process and azeotropic distillation drying method. The effect of azeotropic disstillation process on the formation of gel porous network structure under ambient pressure was discussed, and the changes of xerogel phase and pore structure during calcining process were investigated. The results showed that the particle surface hydrophobic modification and solvent replacement can be simultaneously completed during azeotropic distillation drying process. After calcined at 300°C, the specific surface area and pore volume of SiO2 xerogel is 924.62 m2·g-1 and 0.754 cm3·g-1 respectively, and the pore size distribution is mainly less than 10 nm, which are similar to aerogel in microscopic structure. High temperature is the direct factor of changing particles sinter and pore structure. References | Related Articles | Metrics

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Carbon footprint analysis for key technology of Chinese boron industry An, Jing (1); Xue, Xiang-Xin (1) 2012, 33 (11):  1599-1602.  DOI: - Abstract ( 467 )   HTML   PDF (1553KB) ( 721 )   In order to analyze the environmental impact of global climate change resulting from Chinese boron industry, look for the way to economize energy and decrease pollution emission, carbon footprint resulting from pivotal technology was evaluated with the software of GaBi 4.4. The results showed that the borax production with boron concentrate brings the maximum total carbon footprint and the minimum is brought by the technology with boron-rich slag. Boron-rich slag is a good material to produce borax which can not only save boron resources but also reduce the environmental impact. Of all the boracic acid production technology, the salting out technology with paigeite ore brings the maximum total carbon footprint and the minimum is brought by the floatation technology with szaibelyite. Direct carbon footprint brought by two steps technology is least, but total carbon footprint is more. Reducing energy consumption especially coal is a good method to reduce the carbon footprint of the whole industry system. References | Related Articles | Metrics

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Effects of Cu and La on microstructure and properties of Al-12.6Si alloy Li, Shi-Wei (1); Gao, Bo (1); Tu, Gan-Feng (1); Hao, Yi (1) 2012, 33 (11):  1603-1606.  DOI: - Abstract ( 486 )   HTML   PDF (3312KB) ( 547 )   A series of Al-Si eutectic alloys with different contents of Cu (0.3%, 0.8%, 1.3%, 1.8% and 2.5%) and 0.3% La were investigated. The results showed that the morphology of eutectic silicon is transformed from acicular/lamellar to pointlike and short rodlike when the addition of La is 0.30%, and the alloy reaches the best modification state. With the increasing of Cu content, the number and size of Al2Cu phases, the tensile strength and hardness increase, but the elongation decreases. When the addition of Cu is 2.5%, the tensile strength, elongation and hardness of Al-12.6Si-2.5Cu-0.3La are 241.4 MPa, 4.82% and 83.9 HV, respectively, which increase 58.1%, 41.8% and 30.9%, respectively, compared with those of Al-12.6Si alloy. The mechanical properties of Al-Si eutectic alloy are improved obviously. References | Related Articles | Metrics

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Mechanical properties of acetylated rice straw/PE composite Li, Guang-Lu (1); Wang, Yu-Hong (1); Chao, Yue-Sheng (1); Wang, Lin-Shan (1) 2012, 33 (11):  1607-1610.  DOI: - Abstract ( 392 )   HTML   PDF (2012KB) ( 899 )   The interface compatibility between plant fibres and plastics is poor because the former is polar and hydrophilic, while the latter is nonpolar and hydrophobic. So, WPCs(wood plastic composites), with PE as matrix, natural rice straw and acetylated rice straw as fillers, were prepared by blending and extrusion. The impact of blending conditions on the microstructure and tensile properties was studied. The results showed that the tensile properties of natural rice straw/PE composite were poor due to a large number of bubbles existed within the structure, which resulted in stress defects. After acetylation, the interface compatibility between rice straw and PE was improved remarkably because the polarity and hydrophilism of rice straw fibres were reduced. When the mass fractions of rice straw were the same in WPC, the tensile strength and the elongation at break of acetylated rice straw/PE composites were 1.5 and 2 times those of natural rice straw/PE composites, respectively. References | Related Articles | Metrics

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Reliability analysis of propagation lives of sucker rod's surface crack Li, He (1); Ma, Ming-Wei (1); Tao, Ting (2); Wen, Bang-Chun (1) 2012, 33 (11):  1611-1615.  DOI: - Abstract ( 526 )   HTML   PDF (2040KB) ( 576 )   The crack propagation life was calculated under the tensile load using the sectional type numerical integration method based on the Paris formula considering the relation of geometric modified index f and crack size a. The Monte Carlo method was also used to get the reliability of different types of surface crack propagation lives. The results showed that taking the defect as an elliptical crack governed by depth ration and aspect ratio is better than circular arc crack or straight-edged crack only governed by depth ration. The sucker rods with the circular crack break first. The critical crack propagation life based on the traditional fracture mechanics is not accurate, and the sucker rod may break before the critical crack propagation lives. References | Related Articles | Metrics

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Dynamic analysis of giant magnetostrictive micro-actuator used in turning system Li, Ying (1); Yuan, Hui-Qun (2); Wu, Wen-Bo (2) 2012, 33 (11):  1616-1619.  DOI: - Abstract ( 493 )   HTML   PDF (1869KB) ( 584 )   The dynamics model of giant magnetostrictive actuator (GMA) used in turning system was established and the influence of temperature and pre-stress on output was discussed. The displacements of ideal or hysteresis GMA model appear "roll over" phenomenon under pre-stress. In small incentive magnetic field, the output displacement decreases with increasing the pre-stress, but when incentive is big enough, the trend is opposite. Temperature affects little on the output displacement in small incentive magnetic field, while the output displacement is obvious decrease with the rise of temperature in a bigger incentive magnetic. The results provide theoretical basis for how to deal with the influences of pre-stress, temperature, GMM hysteresis. References | Related Articles | Metrics

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Simulation and experimental research on parallel IPMC Hao, Li-Na (1); Gao, Jian-Chao (1); Sun, Zhi-Yong (1) 2012, 33 (11):  1620-1623.  DOI: - Abstract ( 499 )   HTML   PDF (1376KB) ( 846 )   IPMC(ionic polymer metal composites) as a type of electro active polymer material has some disadvantages of low rigidity, non-desired output displacement, tiny actuating force and low withstanding voltage etc. A novel method was proposed to bond several pieces of IPMC strips together to form multi-layered n-IPMCs using conductive resin. Models of single- and multi-layered parallel connection IPMC micro-actuators were established based on finite element analysis method to predict their output characteristics. Double-layer IPMCs were then fabricated and characterized. The experimental results showed that the double-layer 2-IPMCs are significantly improved in aspects of output force, output displacement, stiffness, withstanding voltage and water retain property compared with that of the single-layer IPMC. References | Related Articles | Metrics

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The method for predicting and controlling the range of surface subsidence during deep ore-body mining Li, Hai-Ying (1); Ren, Feng-Yu (1); Chen, Xiao-Yun (2); Gong, Guo-Hui (2) 2012, 33 (11):  1624-1627.  DOI: - Abstract ( 649 )   HTML   PDF (1279KB) ( 846 )   The surface subsidence range induced by underground mining is commonly predicted by angle of breakage, and this traditional method is not suitable for deep ore-body mining. The actual subsidence range was measured in Gongchangling iron mine and the lateral abutment stress from the moving loosened medium in the subsidence pit was analyzed. As a result, it is showed that the range of surface subsidence is mainly controlled by a critical medium column that could sustain the stability of lateral rock mass, and the factors related to the height of critical medium column are stability of surrounding rockmass, angle of mined-out area, internal friction angle of granular media and the bulking coefficient of rockmass. Accordingly, the measure to controlling surface subsidence range is proposed, and timely backfilling of the subsidence pit with some solid waste materials obtained from the mine production could decrease the critical depth. A formula of subsidence angle is derived from the relation between angle of breakage, depth of mining and height of critical medium column. References | Related Articles | Metrics

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Analysis on roof stability of gob area based on thin plate theory Liu, Xiao-Bo (1); An, Long (1); Zhang, Feng-Peng (1) 2012, 33 (11):  1628-1632.  DOI: - Abstract ( 424 )   HTML   PDF (2363KB) ( 728 )   Gob area in open-pit mine directly influences safe production of operating personnel and large equipment. Based on Navier's solving method of rectangular thin plate with completed clamped supported, deflection equation and stress expressions under uniform load and concentrated load were derived separately, which turns out that the high stress under uniform load and concentrated load is mainly concentrated at the center of the plate and the midpoint of the long side. The factors that influence the stress are thickness, loading condition, dimension and Poisson ratio of the plate. In accordance with the first strength theory, the roof safety equations under uniform load and concentrated load were established, and the critical safety roof thickness was calculated. At last, the correctness of the equations was verified by engineering examples. References | Related Articles | Metrics

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Mechanism analysis on deep reduction of complex refractory iron ore promoted by Na2CO3 Han, Yue-Xin (1); Zhang, Cheng-Wen (2); Sun, Yong-Sheng (1); Gao, Peng (1) 2012, 33 (11):  1633-1636.  DOI: - Abstract ( 494 )   HTML   PDF (1854KB) ( 856 )   Effect of Na2CO3 on deep reduction of antelope iron was studied under the temperature of 1200°C and duration of 40 min. Characteristics of solid-state in deep reduction was analyzed by thermodynamic analysis. Complex iron compound such as fayalite and hercynite that was generated during deep reduction is one of the primary factors that affect metallization rate and the index of iron powder. According to analysis, FeO is replaced from complex iron compound by Na2O, which is decomposed from Na2CO3. At the same time, because of reactions between SiO2, and Al2O3, the amount of SiO2 and Al2O3 that may react with FeO is effectively reduced, thus improving the metallization rate and the index of iron powder. References | Related Articles | Metrics

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Modification of natural zeolite and its adsorption of Pb2+ and Cu2+ Wang, Ze-Hong (1); Tao, Shi-Jie (2); Yu, Fu-Jia (1); Li, Yan-Jun (1) 2012, 33 (11):  1637-1640.  DOI: - Abstract ( 679 )   HTML   PDF (1552KB) ( 1123 )   The natural zeolite was used as the experimental material, in combination the requirements of adsorption materials used to treat waster water, the natural zeolite was modified by acid, alkali and salt. The method, removal efficiency, influencing factors and adsorption mechanism for removing of heavy metal ion, such as Pb2+ and Cu2+, from solution using modified zeolite were also studied. The results showed that adsorption capacity of Pb2+ and Cu2+ in zeolite modified by NaOH can be improved greatly. The adsorption capacity of Pb2+ and Cu2+ in modified zeolite rises with the increase of initial concentration. Modified zeolite adsorbs Pb2+ and Cu2+ very quickly, and the equilibrium can be reached in shorter time. The higher pH of heavy metal ion solution the better it is for the adsorption of Pb2+ and Cu2+. References | Related Articles | Metrics

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Regional prediction of debris flow based on random forest regression tree model case study in Fengcheng City Fu, Jian-Fei (1); Men, Ye-Kai (1); Hou, Gen-Qun (1); Zhao, Chun-Fu (1) 2012, 33 (11):  1641-1644.  DOI: - Abstract ( 418 )   HTML   PDF (1875KB) ( 545 )   On the basis of 16 independent variables (including 8 remote sensing factors, 3 DEM factors, 4 soil factors and 1 formation lithology factor), the intraday precipitation rainfall and that in preceding day were extracted as the dependent variable respectively, and the random forest regression tree model was built to predict the debris flows in the regional scale on the platform of GIS. The predicting results shows that, the lithology, elevation and aspect are the main factors influencing the occurrence of debris flow, and the increasing precipitation improved the importance of the soil factors in the occurrence of debris flow. Among the 8 remote sensing factors, the clay factor has the greatest impact on the debris flow. In the southeast, the debris flow would occur when the accumulated precipitation goes higher. On the contrary, in the northwest, a small amount of accumulated precipitation would result in the occurrence of debris flow, and the continuous precipitation would increase the incidence of debris flow from the daily and two day precipitation warning charts. References | Related Articles | Metrics

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A parameter prediction model for layered soil based on GA-ANN algorithm Li, Chun (1); Zhu, Fu-Sheng (1); Fu, Shi-Meng (1); Zhang, Miao (1) 2012, 33 (11):  1645-1648+1653.  DOI: - Abstract ( 691 )   HTML   PDF (919KB) ( 692 )   BP neural networks and genetic algorithm were combined together to establish the self-adaptive genetic algorithm and BP neural network system, and were used to predict the parameters of layered soil. Lots of physical and mechanical parameters of different layered soils are sorted out and used as the sample, then, the target parameters of layered soil were predicted. The results predicted with two kinds of intellectual technologies were compared with those predicted with BP neural networks. It shows that the ideal prediction results can be obtained simultaneously by the two technologies while variance of the sample data is small. The established system can also provide itself the generalization function to prevent the case "overfull training". When sample scale and variance of sample data are both big enough, the superiority of the network system can be better expressed. References | Related Articles | Metrics

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Simulation analysis of temperature/humidity independent control air conditioning system with exhaust air heat recovery Han, Zong-Wei (1); Zhao, Jing (1); Ding, Hui-Ting (1); Na, Wei (2) 2012, 33 (11):  1649-1653.  DOI: - Abstract ( 778 )   HTML   PDF (2262KB) ( 745 )   The exhaust air heat recovery fresh air unit, which consists of total heat exchanger and heat pump unit, was put forward, and the fresh air unit, was applied in fan coin air conditioning system for realizing temperature and humidity independent control. An office building in Nanjing is selected, and the annual hourly air conditioning load is calculated by DeST software. The mathematic model for simulating performance of the system is set up. The simulation analysis of cooling performance of the system in typical year is carried out. The simulation results showed that the system can independent control temperature and humidity well, and the coefficient of performance (COP) of the system is 4.58. The energy saving rate of the system is 42.8% compared with conventional air conditioning system. References | Related Articles | Metrics

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Relief preparation plan for natural disasters: A stochastic programming model and case Qin, Xu-Wei (1); Liu, Xiao (2); Li, Kai (1) 2012, 33 (11):  1654-1659.  DOI: - Abstract ( 483 )   HTML   PDF (2233KB) ( 777 )   The relief preparation of adequate facilities and resources in areas frequently struck by natural disasters is a cornerstone that guarantees the effective execution of relief operations. Within a limited budget, a two-stage stochastic programming model is developed with an aim to minimizing the expected number of casualties. The first stage of the model is focused on pre-disaster strategic decisions including the expansion of hospitals and shelters, the site selection of warehouses, the allocation of emergency supplies and relief vehicles, and the second stage is concerned with operational decisions on emergency logistics plans, including taking the wounded from disaster areas to hospitals, transferring the victims from disaster areas to shelters, sending the medical supplies from warehouses to hospitals and shelters, and dispatching the living materials from warehouses to resettlement areas. The computational results of an illustrative case prove the validity of the proposed stochastic optimization model. References | Related Articles | Metrics

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Human capital and investment performance of venture capital firms mediating and moderating effects of investment strategies Li, Yan (1); Zhuang, Xin-Tian (1); Luo, Guo-Feng (2); Ma, Shi-Mei (2) 2012, 33 (11):  1660-1663+1668.  DOI: - Abstract ( 444 )   HTML   PDF (1301KB) ( 677 )   Based on the postulated mediating effect of early stage investment and moderating effect of syndication, this paper discussed the impacts of venture capital firms' human capital on investment performance by using Chinese VCFs' data. Regression analysis and structural equation model were used to test the models of mediating and moderating effects. The results indicated that there is a positive relationship between human capital and investment performance therein the early stage investment provides partial mediating effect, and the indirect effect amounts to 58.93%. Besides, syndication can serve as a moderator between human capital and early stage investment as well as between human capital and performance. With the increase of syndication, the former relationship is enhanced, while the latter one goes down. References | Related Articles | Metrics

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An empirical study of the effect of stock price informativeness on corporate capital allocation efficiency Yuan, Zhi-Zhu (1); Wu, Li (1); Ju, Xiao-Feng (2) 2012, 33 (11):  1664-1668.  DOI: - Abstract ( 509 )   HTML   PDF (971KB) ( 942 )   Taking Chinese listed companies as the research sample and adopting stock price non-synchronicity to measure stock price informativeness, an empirical test was carried out to explore the causal relationship between stock price informativeness and capital allocation efficiency based on the regression models of panel data. The results indicated that a significantly negative relationship exists between price informativeness and corporate overinvestment; in other words, the information exclusive to stock price can inhibit overinvestment and then improve capital allocation efficiency. Moreover, high stock price informativeness can significantly enhance future operating performance. Consequently, stock price informativeness has a positive effect on optimal capital allocation. References | Related Articles | Metrics

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Determination of the EPR regulation standards from the perspective of social welfare maximization Tian, Hai-Feng (1); Li, Kai (1); Sun, Guang-Sheng (1) 2012, 33 (11):  1669-1672.  DOI: - Abstract ( 450 )   HTML   PDF (1218KB) ( 611 )   From the perspective of social welfare maximization, a product life cycle model involving both producers and consumers was built in which the regulation standards for both recycling and reducing were determined, and the major factors affecting the optimal standards were discussed. The results showed that the socially optimal condition is reached when the value of each marginal product equals its net price, and the recycling cost, input's marginal contribution, price of material input, cost of waste disposal are the most important factors for the optimal standards. Therefore, in order to maximize the social welfare, policy makers should take both environmental and economic performances into account while making EPR (extended producer responsibility) regulation policies. References | Related Articles | Metrics