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15 April 2010, Volume 31 Issue 4 Previous Issue    Next Issue
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H∞ control of quantized continuous-time networked control systems Liu, Ying-Ying (1); Yang, Guang-Hong (1) 2010, 31 (4):  457-460.  DOI: - Abstract ( 320 )   HTML   PDF (571KB) ( 791 )   How to control the continuous-time networked control systems (NCSs) with two quantizers in static form was considered, where two signals, i.e., state and control input, were quantized separately on the sides of sensors and controllers. The conditions for analyzing the H∞ performance of quantized NCSs were presented in terms of linear matrix inequalities (LMIs), which were obtained by the Lyapunov function and Jessen inequality methods with the technique of relaxation variables and sector bound method introduced. Then, a quantized H∞ controller was designed by solving LMIs. A numerical example was given to illustrate the effectiveness of the proposed method. References | Related Articles | Metrics

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Network congestion control algorithm based on T-S fuzzy observer Wang, Hong-Wei (1); Yu, Chi (1); Jing, Yuan-Wei (2) 2010, 31 (4):  461-464+468.  DOI: - Abstract ( 337 )   HTML   PDF (230KB) ( 695 )   To solve the problem of network congestion control in accordance to TCP (transmission control protocol), an active queue management (AQM) algorithm was designed on the basis of fuzzy observer. With a T-S fuzzy model developed for the nonlinear TCP/IP network congestion control system, the performance of the network system was improved by choosing appropriate fuzzy rules and membership functions, and the stability of the system was proved theoretically. Simulation results in different scenarios demonstrated that the proposed controllers are highly stable and robust in respect to the uncertainties of the number of active TCP sessions, link capacity and the round-trip time (RTT). References | Related Articles | Metrics

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Credit evaluation model based on time series fuzzy clustering and rule extraction Zhang, Hong-Xiang (1); Mao, Zhi-Zhong (1) 2010, 31 (4):  465-468.  DOI: - Abstract ( 330 )   HTML   PDF (167KB) ( 854 )   A fuzzy classification system was presented by combining the multidimensional time series fuzzy clustering with rule extraction to evaluate the credit. This method was applied to the dimensionality reduction of multidimensional time series via projection pursuit technique for fuzzy clustering. According to the results of the classification and the extraction of fuzzy rules through best value projection, three types of fuzzy membership function were generated using trapezoid distribution method. Then the sample's credit level was determined according to the fuzzy approximability in computation. Exemplification results showed that this method is good at evaluation effectiveness and practicality. References | Related Articles | Metrics

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Identification algorithm of Hammerstein-Wiener model with process noise and its convergence analysis Li, Yan (1); Mao, Zhi-Zhong (1); Wang, Yan (1); Yuan, Ping (1) 2010, 31 (4):  469-472+476.  DOI: - Abstract ( 432 )   HTML   PDF (392KB) ( 771 )   A bias-compensated recursive least squares (BCRLS) algorithm was proposed to identify the Hammerstein-Wiener model with process noise, i.e., the bias compensation was introduced into the recursive least squares algorithm. The parameter vector containing the product of the original system parameters was thus identified on-line. Then, the convergence of the algorithm was proved by the martingale convergence theorem. It was found that the estimation error of parameter product uniformly converges to zero during persistent excitation. Simulation results showed that the proposed method is better than the identification method by recursive least squares. References | Related Articles | Metrics

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Measuring mass flowrate of gas-solid two-phase flow by electrostatic sensors Kan, Zhe (1); Shao, Fu-Qun (1) 2010, 31 (4):  473-476.  DOI: - Abstract ( 363 )   HTML   PDF (1093KB) ( 767 )   In view of the complex flowing states of gas-solid two-phase flow, the expressions of solid mass concentration relevant to the two-phase flow were deduced on the basis of fluid mechanics when the flow is in the up, horizontal or down conveying pipeline. Then, with the measuring technique on the principle of cross-correlation used to measure the velocity parameter, an indirect measurement was done for the mass flowrate of gas-solid two-phase flow according to the formula of solid-phase mass flowrate and the expression of mass concentration. References | Related Articles | Metrics

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Improving RHS for energy saving Deng, Qing-Xu (1); Kong, Fan-Xin (1); Xu, Hui-Ting (1); Jin, Xi (1) 2010, 31 (4):  477-481.  DOI: - Abstract ( 474 )   HTML   PDF (426KB) ( 698 )   Several improvements for ES-RHS algorithm are proposed by taking account of both the schedulability test and the time/energy overhead due to processor mode switching. A new schedulability test condition which heavily reduces the pessimism is first presented. Then, the power consumption can be reduced by merging the tasks together and eliminating the idle mode of processor, thus decreasing greatly the number of mode switching acts. Furthermore, the constraint on the sleeping time of the processor in every harmonic period is relaxed. Simulation results indicate that the proposed algorithm reduce the power consumption by 17%~65% and is applicable to more types of processors in comparison to ES-RHS. References | Related Articles | Metrics

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Medium/long-term load forecasting based on DPCA-BP neural network Zhang, Shi (1); Zhang, Rui-You (1); Wang, Ding-Wei (1) 2010, 31 (4):  482-485.  DOI: - Abstract ( 405 )   HTML   PDF (1289KB) ( 663 )   The result of the load forecasting based on PCA neural network cannot meet the accuracy required with the autocorrelation between data being ignored. An augmented matrix is therefore given, of which the number of dimensions is determined by adding the observed data for l time past together, and the forecast data after augmentation are taken as the input variables in BP neural network. Then, a forecasting model is developed on the basis of DPCA-BP neural network, with its architecture described. The model can exclude efficiently the data irrelevant to dependent variables from the independent variable system so as to intensity the autocorrelatability between data of the independent variable system. Compared the two methods of load forecasting with each other, the exemplification results show that the load forecasting model we developed is better than that based on PCA-BP neural network, since it provides higher interpretability and forecasting accuracy. References | Related Articles | Metrics

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Computing rooted communication reliability of cyclic directed networks using the factoring method Sun, Yan-Rui (1); Bi, Ji-Guo (2); Zhang, Xiang-De (1) 2010, 31 (4):  486-489.  DOI: - Abstract ( 318 )   HTML   PDF (696KB) ( 638 )   A reliability-preserving reduction and an factoring edge-selection strategy are presented by using the topological structure of cyclic directed network. Then, an efficient factoring algorithm is developed to compute the rooted communication reliability of cyclic directed networks. The time complexity of the algorithm is O(N·(|V|+|E|)), where N is the total number of the nodes as leaves on the binary tree originated from the algorithm, and |V| and |E| are the numbers of nodes and edges in a network, respectively. With some networks computed by the algorithm, it is found that the value of N resulting from computing the rooted communication reliability is much less than that resulting from other algorithms, thus verifying the higher effectiveness of the algorithm proposed. References | Related Articles | Metrics

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Hopf bifurcation of cortical column model Li, Chun-Sheng (1); Wang, Hong (2); Zhang, Xue (3); Zhao, Hai-Bin (2) 2010, 31 (4):  490-493.  DOI: - Abstract ( 372 )   HTML   PDF (264KB) ( 735 )   A class of cortical column models with lumped parameters was studied, where the stability of equilibrium point was analyzed with the conditions for Hopf bifurcation given. Numerical simulation showed that the model can generate several kinds of EEG-like waveforms with different parameters. Changing the external pulse density to be input, the state response of the model undergoes a change from stable point to limited cycle, thus verifying the existence conditions for Hopf bifurcation. The study on bifurcation of EEG provides theoretically further reference for grasping brain's nonlinear structure. References | Related Articles | Metrics

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Sintering condition prediction based on SVM and PSO Jiang, Hui-Yan (1); Jing, Shi-Lei (1); Chai, Tian-You (2); Zhou, Xiao-Jie (2) 2010, 31 (4):  494-497.  DOI: - Abstract ( 343 )   HTML   PDF (1123KB) ( 544 )   Sintering condition images that were collected online in rotary kiln were denoised by rolling-ball algorithm, then the ROI (regions of interest) such as the material, flame and full combustion zones in the denoised images were segmented by Otsu method and double fast marching method. With some features extracted from the ROI then reduced on the basis of the RelieF-GA method, the SVM model parameters were optimized via PSO algorithm to develop a model to predict the sintering conditions. Lots of experimental results verified that this method can improve the prediction rate of sintering condition greatly. References | Related Articles | Metrics

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A SON-oriented unicast routing protocol Wang, Xing-Wei (1); Li, Xue-Jiao (1); Huang, Min (1); Wen, Zhan-Kao (1) 2010, 31 (4):  498-502.  DOI: - Abstract ( 372 )   HTML   PDF (511KB) ( 577 )   A SON-oriented unicast routing protocol was proposed to meet the requirements for QoS and support the biological behaviors of router. The protocol was designed by extending OSPFv3/BGP4+, including intra-autonomous-domain and inter-autonomous-domain protocol message formats and functions, link state description structures, neighborhood tables, unicast routing tables and protocol processing procedures. Implementing over the Quagga software router, the performance of the protocol was evaluated with Iperf tool on a network testing platform. The results showed that the proposed protocol is effective with better performance. References | Related Articles | Metrics

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A new PAPR reduction algorithm for SFBC MIMO-OFDM system Sha, Yi (1); Chen, Jun-Xin (1); Chen, Jin (1); Wang, Guang-Xing (1) 2010, 31 (4):  503-506.  DOI: - Abstract ( 375 )   HTML   PDF (293KB) ( 769 )   A new algorithm named twice-partial transmit sequence (T-PTS) algorithm is proposed to reduce the PAPR of SFBC MIMO-OFDM system. In this algorithm, a transmit sequence is partitioned adjacently, and then every adjacent partitioned subblock is repartitioned in an interlacing way. After rotating both the adjacent and interlaced subblocks twice, a best sequence whose PAPR is minimal is chosen to transmit so as to reduce PAPR. To simplify the search process of weights, a RT-PTS (reduced T-PTS) algorithm, which takes advantage of SFBC in combination with the circular shift and conjugation of IFFT, is proposed to suboptimize the T-PTS algorithm, thus reducing the computation complexity. Simulation results showed that the RT-PTS algorithm can restrict the PAPR effectively at the same time of keeping low computation complexity in comparison with conventional methods. References | Related Articles | Metrics

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Comparative analysis of characteristics of internet topology at router-level Zhao, Hai (1); Fu, Yao (1); Zheng, Yan-Qin (1); Li, Chao (1) 2010, 31 (4):  507-510.  DOI: - Abstract ( 359 )   HTML   PDF (399KB) ( 754 )   The change of CAIDA detection mode from Skitter to Ark was investigated, based on the data of Ark project over February 27~29, 2008 and that of Skitter project on August 16, 2007. Setting up the network topology and analyzing the difference between the data measured from single vantage points and integrated data in several characteristics values, e.g., the degree of average, clustering coefficient and coreness, the errors of measured data sets from single vantage points in Skitter and Ark projects were compared with each other, as well as the degree distributions of their measured data. The results revealed that the errors of the measured data from single vantage points in Ark project are slightly smaller, and that the two data sets in both projects are basically the same with few discrepancies. References | Related Articles | Metrics

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Fractals of internet router-level topology based on k-core decomposition Zhang, Jun (1); Zhao, Hai (1); Kang, Min (2); Wang, Wei (1) 2010, 31 (4):  511-514+518.  DOI: - Abstract ( 337 )   HTML   PDF (2632KB) ( 785 )   The fractal features of Internet topology was studied at router level by analyzing the massive data authorized by CAIDA (cooperative association for Internet data analysis) Skitter project. According to the definition of k-core, the Internet topology was divided into different cores at router level. Analyzing the main characteristic quantities such as degree distribution, degree correlations and clustering coefficient of every k-core, it was found that the degree distribution, clustering and correlation structure of Internet topology are all kept on as the network is pruned inwards step by step. The fact implies that there is a global self-similarity at the router level of Internet topology, which is approaching inwards to the center of the network. Furthermore, any region in Internet, which is defined according to the network centrality, has such a structure that its properties are the same to the topology of the whole network. All of these prove that Internet topology has fractal features at router level. References | Related Articles | Metrics

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Effect analysis of a newly developed electromagnetic steel tapping system Gao, Ao (1); Wang, Qiang (1); Jin, Bai-Gang (1); He, Ji-Cheng (1) 2010, 31 (4):  515-518.  DOI: - Abstract ( 316 )   HTML   PDF (1038KB) ( 636 )   With the mixture of iron particles and carbon powder used instead of the conventional nozzle sand in the electromagnetic steel tapping system, the distribution of temperature field in nozzle upper was simulated for 1, 3?h and in steady state (infinite time) by the FEM software ANSYS. It was found that the temperature of the Fe/C mixture decreases gradually from top to bottom, thus forming a certain temperature gradient. Then, it was verified that the iron particles in the mixture can be melted quickly on certain process parameters so as to make sure that the operation of steel tapping from ladle is successful. How the ladle refractory meets the technological requirements in the electromagnetic steel tapping process was discussed. And the safety of the ladle bottom plate under the action of electromagnetic induction heating was checked via the distribution of temperature field on the plate. References | Related Articles | Metrics

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Temperature field analysis of plasma-sprayed coatings for thin-wall parts Niu, Li-Ping (1); Zhang, Ting-An (1); He, Ji-Cheng (1); Dou, Zhi-He (1) 2010, 31 (4):  519-522.  DOI: - Abstract ( 326 )   HTML   PDF (2325KB) ( 536 )   The causes of residual stress in plasma sprayed coating are mainly the thermal gradient in deposited layers and the different heat expansion coefficients of coating and substrate. Taking account of the increment in thickness of each layer sprayed, an analytical model of temperature field was developed for the sprayed particles in their deposition process, where the composite effects of heat transfer and thermal radiation on the coating were also considered. Thus, the coating's temperature field was calculated for different substrate-coating systems. The results revealed that temperature rise during the deposition of layers can be divided into two stages, i.e., the temperature of the substrate-coating system does not exceed 15% the melting point of the material being sprayed; the temperature of the system rises continuously and achieves the maximum value after the heat balance between the substrate and coating, then the residual stress forms on the interface between substrate and coating. References | Related Articles | Metrics

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Water modeling on oxygen absorption and decarburization in RH-KTB process Geng, Dian-Qiao (1); Lei, Hong (1); Liu, Ai-Hua (2); He, Ji-Cheng (1) 2010, 31 (4):  523-526.  DOI: - Abstract ( 424 )   HTML   PDF (971KB) ( 547 )   To grasp the mass transfer in RH-KTB vacuum refining process, a water modeling was done on the scale of 1:5.5, and the NaOH-CO2 solution system was used to investigate the effects of different process parameters on the oxygen absorption, decarburization and degassing processes. The experimental results showed that either increasing the lifting gas flowrate and top blowing gas flowrate or decreasing the top lance height benefit the absorption rate of top blowing oxygen, while increasing the lifting gas flowrate benefits decarburization. The liquid surface level in the vacuum chamber has an optimum value for the absorption process of oxygen. When blowing oxygen with a top lance, the vacuum degree should reach its optimum value for fast absorption of oxygen. Moreover, when stopping the top blowing oxygen operation, the vacuum degree should be increased as high as possible to accelerate decarburization. References | Related Articles | Metrics

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Temperature field of steel plate on roller quenching machine Yuan, Guo (1); Wang, Guo-Dong (1); Wang, Li-Jun (2); Wang, Zhao-Dong (1) 2010, 31 (4):  527-530+538.  DOI: - Abstract ( 572 )   HTML   PDF (1781KB) ( 989 )   The effects of heat transfer coefficient and quenching modes on the temperature field of a steel plate during quenching on a roller quenching machine were analyzed by a heat transfer control equation derived. The results showed that if the heat transfer coefficient increases within a certain range, the boundary conditions of convective heat transfer affect the surface and internal temperature of a plate of certain thickness significantly in its quenching process. It was found that the roller quenching machine has such characteristics that the steel plate is cooled in a high-pressure quenching zone where the cooling intensity is so high that the temperature gradient can be kept great inside the plate to ensure its high cooling rate, then the plate is fully quenched in the low-pressure quenching zone with lower cooling rate, thus decreasing the temperature gradient in the plate with its internal thermal stress reduced. References | Related Articles | Metrics

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On the high-temperature dephosphorization of monazite concentrate with coking coal Xing, Peng-Fei (1); Tu, Gan-Feng (1); Gao, Hao-Jun (2); Wu, Wen-Yuan (1) 2010, 31 (4):  531-534.  DOI: - Abstract ( 386 )   HTML   PDF (859KB) ( 878 )   Viewing the industrial applications in future, the high-temperature dephosphorization of monazite concentrate with coking coal was investigated experimentally. The results showed that coking coal is one of the efficient reducing agents for the dephosphorization of monazite concentrate, to which the dephosphorizing temperature is mainly in the range from 1200 to 1400°C. When the monazite pellets, made by pressing monazite, coking coal and water together in mould, are roasted for 2h at 1400°C, the dephosphorizing rate of monazite comes up to 96.5%. The roasting temperature is the main influencing factor on the dephosphorization of monazite, while the influence of roasting time on the dephosphorization is unobvious if it is over 1h. The particle size of coking coal also has influence on the dephosphorization of monazite, and the size about 150μm is better. Fe and Fe2O3 have scarcely any influence on the dephosphorization of monazite. References | Related Articles | Metrics

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Effect of casting temperature on microstructure of AZ31 alloy in continuous rheo-extrusion process Zhao, Zhan-Yong (1); Guan, Ren-Guo (1); Li, Jiang-Ping (1); Wang, Fu-Xing (1) 2010, 31 (4):  535-538.  DOI: - Abstract ( 407 )   HTML   PDF (1469KB) ( 814 )   Casting temperature is the main influencing factor on microstructure in the continuous rheo-extrusion process of AZ31 magnesium alloy. The microstructures of AZ31 magnesium alloy at different positions in the roll-shoe die cavity during continuous rheo-extrusion were investigated at different casting temperatures. The results showed that the semi-solid zone becomes smaller when the casting temperature is higher than 750°C, and the time the work roll takes to prune the dendrite in the semi-solid zone is shortened, i.e., the dendrite has not been fully broken up, thus making the high-quality semi-solid alloy unavailable. On the other hand, when the casting temperature is lower than 730°C, the solid-state zone becomes bigger and the semi-solid zone where part of the dendrite has not been fully pruned is merged into the solid-state zone, thus making the dentrite in solid-state zone more difficult to be broken up. As a result, it's impossible to get an ideal semi-solid microstructure. With the solidification zone thus increased, the alloy is deformed more difficultly with increasing working pressure needed for the equipment system and its service life shortened. The best casting temperature is 730~750°C in the continuous rheo-extrusion process of AZ31 alloy. References | Related Articles | Metrics

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Study on adsorbability of mould flux to Al2O3 inclusion Lu, Yan-Qing (1); Zhang, Guo-Dong (2); Jiang, Mao-Fa (1); Liu, Hai-Xiao (2) 2010, 31 (4):  539-541.  DOI: - Abstract ( 395 )   HTML   PDF (850KB) ( 780 )   The effects of the adsorption of Al2O3 inclusion of different contents on the melting temperature, viscosity, surface tension and crystallinity of the mould flux were studied. The results showed that the melting temperature and viscosity increase but the surface tension decreases after the Al2O3 inclusions are adsorbed. When the basicity of mould flux is in the range from 0.85 to 1.17, the changes in its melting temperature and viscosity are small with the adsorbability kept well. When the basicity is in an appropriate range from 0.92 to 1.07, the surface tension changes little so as to benefit the adsorption of inclusions. With the increasing of Al2O3 inclusions, the quantity of cuspidite and grammite in mould flux decrease. References | Related Articles | Metrics

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Ecological pressure analysis of thermometallurgical separation process of paigeite ore An, Jing (1); Xue, Xiang-Xin (1); Jiang, Tao (1) 2010, 31 (4):  542-545.  DOI: - Abstract ( 344 )   HTML   PDF (533KB) ( 538 )   A thermometallurgical separation technics was excogitated by the Northeastern University for the comprehensive resource utilization of the paigeite ore in Liaoning. To analyze the ecological pressure resulting from the process quantitatively, an attempt was made to calculate the ecological footprints caused by the whole industrial system, every link in production and products with a component-based model. The results showed that the ecological footprints caused by mining and processing every 10000t of paigeite ore are 2319.3023hm2, where the separation by blast furnace is the biggest, i.e., 79% and only 1% is caused by mineral processing. As to the products, boron-bearing iron, the ecological footprints per 10, 000t in production is up to 7254.9849hm2 which is bigger than that of the same outputs of the borax produced by either boron-rich slag or boron concentrate, i.e., 4438.6560hm2 and 6177.4442hm2, respectively. In view of the types of land occupied, the ecological footprints resulting from the utilization of fossil energy are dominant. References | Related Articles | Metrics

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Experimental study on drying process of mixture being sintered utilizing waste heat Dong, Hui (1); Guo, Ning (1); Yang, Liu-Qing (2); Cai, Jiu-Ju (1) 2010, 31 (4):  546-549.  DOI: - Abstract ( 226 )   HTML   PDF (877KB) ( 516 )   An experimental setup was developed to test the drying process of a mixture (in kg) being sintered, with the effects of drying air flowrate and temperature on the drying process investigated. The results revealed that the whole drying process can be divided into three stages according to the drying rate, i.e., the short rate-rising, long constant rate and fixed rate-dropping, among which the long constant rate stage can further be divided into 2~3 substages. The water contents corresponding the three stages are 6.5%~7.5%, 2%~6.5% and below 2%, respectively. The rate-rising stage occurs in about the first 10min of the drying process and the rate comes up to its maximum value when the water content is 7.0%~7.5%. The critical water content changes in the range from 1.6%~2.8% under different experimental conditions, and the drying air flowrate and temperature are both verified the main influencing factors on drying process. To a certain extent, the higher the air flowrate and temperature, the higher drying rate, but the relationship between air flowrate or temperature and drying rate is nonlinear. Both drying air flowrate and temperature should be set in appropriate range. References | Related Articles | Metrics

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Study on mechanism of coal tar pyrolysis Wang, Lian-Yong (1); Cai, Jiu-Ju (1); Li, Ming-Jie (1); Sun, Hua-Cheng (1) 2010, 31 (4):  550-554.  DOI: - Abstract ( 656 )   HTML   PDF (530KB) ( 1290 )   Simultaneous thermogravimetry-mass spectrometry (TG-MS) was used to investigate the pyrolysis behavior of coal tar and the instantaneous evolution characteristics of gaseous products, and the pyroletic reaction mechanism of coal tar was inferred by the double extrapolated method. Data processing/fitting was conducted introducing the Costs-Redfern and the Flynn-Wall-Ozawa integration methods, thus giving the two-stage reaction mechanism function of weightlessness and kinetic parameters. The results showed that mainly there are two weight loss stages during coal tar pyrolysis. The first one is a polycondensation process of organic reaction after dehydration, which is mainly affected by the random nucleation mechanism and, as a result, the old phase disappears with new phase generated for nucleation. In the stage the main products are micromolecular gases and macromolecular condensed tar, and the activation energy is 162kJ/mol. In the second stage the pyrolysis occurs once again for the macromolecules of condensed tar under the control of three-dimensional diffusion mechanism, which reflects the mutual transfer mechanism between gaseous products. Moreover, in the second stage the nuclei are growing and diffusing, where the products are mainly the hydrogen and carbon monoxide with an activation energy 76.68kJ/mol. References | Related Articles | Metrics

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Selection of flotation desulfurization collector for high-sulfur bauxite Wang, Xiao-Min (1); Zhang, Ting-An (1); Lü, Guo-Zhi (1); Bao, Li (1) 2010, 31 (4):  555-558.  DOI: - Abstract ( 433 )   HTML   PDF (1681KB) ( 1222 )   The desulfhurization performance of 5 flotation collectors for high-sulfur bauxite were investigated, i.e. the dodecyl sodium sulfate, ethyl xanthate, ethyl thiocarbamate, butyl xanthate and isobutyl xanthate, where the influence of dose, floating time, pulp density, pH value and ore grain size on the desulfurization rate and alumina flotation recovery were emphasized. The results showed that the dodecyl sodium sulfate has no floatability for desulfhurization, and that of either ethyl xanthate or ethyl thiocarbamate is limited to a certain extent. And the butyl xanthate and isobutyl xanthate both have high floatability for desulfhurization, so they are suitable for industrial applications. The open-circuit experiments of butyl xanthate and isobutyl xanthate showed that the latter has higher selectivity but the former has strong collectability. References | Related Articles | Metrics

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Enriching metallic nickel from laterite-nickel ore via thermal carbon reduction-magnetic separation process Xu, Dong (1); Liu, Yan (1); Li, Jie (1); Zhai, Yu-Chun (1) 2010, 31 (4):  559-563.  DOI: - Abstract ( 412 )   HTML   PDF (1535KB) ( 799 )   The low-grade laterite-nickel ore was treated by thermal carbon reduction-magnetic separation process to enrich the metallic nickel with activated carbon powder as reductant. With the additive A added in the pre-reduced pellets to stimulate the growth of metallic grains in them and magnetic separation of magnetic substance from nonmagnetic substance, the reduction reaction of laterite-nickel ore occurred at the temperature below conventional melting point, thus, reducing greatly the energy consumption. The testing results showed that the optimal reduction conditions are 1320°C for 120min and the proportional mass fractions of activated carbon powder and the additive A are 3% and 5%, respectively. The additive A accelerates the aggregation of metallic grains so as to make the enriched metallic grains easier for magnetic separation. The mass fraction of maximum nickel in ferronickel alloy and nickel recovery in the laterite-nickel ore are 8.31% and 95.44%, respectively. Metallic nickel is thus enriched. The proposed process has such advantages as short in procedure, easy to operate, low energy consumption and high economic benefit from ferronickel alloy. References | Related Articles | Metrics

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On recovery of iron from wastewater after bio-oxidation extraction of gold Li, Qian (1); Tian, Yan-Wen (1); Li, Jian-Zhong (1) 2010, 31 (4):  564-567.  DOI: - Abstract ( 287 )   HTML   PDF (2459KB) ( 863 )   The transparent iron oxide yellow was prepared by using the yellow precipitates after separating arsenic and iron from the wastewater. The effects of pH value, stirring speed, reaction temperature and dose of surfactant on the transparency of iron oxide yellow were investigated. The results showed that when the pH value is 3.5, stirring speed 600r/min, reaction temperature 25°C and dose of surfactant 3%, the transparency of regularly prepared iron oxide yellow is 87% at 540nm. As a product, the iron oxide yellow made in such a way is in accordance with ISO1248-1974, thus realizing the waste recovery of iron from acidic arsenic-containing wastewater and its applications. References | Related Articles | Metrics

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Geometric parameters of cracked inclusions and their effects on elastic modulus of composites Zhao, Li-Jun (1); Huang, Bao-Zong (2) 2010, 31 (4):  568-571.  DOI: - Abstract ( 339 )   HTML   PDF (1569KB) ( 599 )   The conventional geometric parameters relevant to inclusions, i.e., aspect ratio and volume fraction, are unsuitable to the micromechanical study on inclusions if taking the coin-like crack as inclusions of which both the aspect ration and volume fraction approach zero. The fact has been verified via numerical exemplification. So, two other parameters are introduced to describe the geometric characteristics of cracked inclusions, i.e., the crack area fraction and the aspect ratio of representative volume element. Then, based on Mori-Tanaka method, the elastic modulus is calculated for a composite in which the unreinforced and fiber-reinforced matrices both contain the coin-like cracks as inclusions with different geometric parameters. The applicability of the two new parameters are verified with their effects discussed. References | Related Articles | Metrics

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Evaluation and prediction of mo-polymetallic deposit based on weight of evidence in West Liaoning Jia, San-Shi (1); Yang, Yi-Biao (1); Men, Ye-Kai (1); Wang, En-De (1) 2010, 31 (4):  572-575.  DOI: - Abstract ( 345 )   HTML   PDF (459KB) ( 775 )   Based on the GIS-data-driven model in combination with the weights of evidence and basic geological data, the information on the relevant structure, alteration and mineralization can be extracted from remote sensing images to evaluate the resource potential quickly. The Mo-polymetallic deposit in West Liaoning were thus evaluated with 8 factors, i.e., the upper Cambrian-Ordovician, Yixian formation, Wumishan formation, Yanshan-period granite, alteration of clay, intensity of Fe2+, intensity of Fe3+ and tectonic intensity. Such an evaluation is feasible as proved mathematically by X2 independence test, and its results conform to the three existing deposit-concentrated areas. Gaojialing and Hongyazi were predicted to be the two mineralogenetic areas. References | Related Articles | Metrics

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Trend forecast and scenario simulation analysis of ecological footprints in China Zhang, Bo (1); Wang, Qing (1); Liu, Jian-Xing (2); Gu, Xiao-Wei (1) 2010, 31 (4):  576-580.  DOI: - Abstract ( 251 )   HTML   PDF (308KB) ( 1090 )   To improve the ecological footprints in statics and get rid of the deficient function of forecast, a trend analysis and scenario simulation analysis were made for China's ecological footprints. The results showed that China's ecological footprints still present an upward trend, since the growth rate of the efficiency of resource utilization was faster than GDP growth rate in China's economic development, but they were still in coordination and the resources pressure will be at a low level in the near future. Nevertheless, in the risky circumstances the change in resource utilization efficiency lags behind the economic development with the resource pressure increased gradually, which will cause an enormous impact on not only China herself but also the global natural ecosystem. The only way to reduce the resource/ecology pressure in China is to improve rapidly the efficiency of resource utilization. References | Related Articles | Metrics

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Optimization analysis of Changshu city size based on SD-MOP Gao, Cheng-Kang (1); Bao, Cun-Kuan (2); Dong, Jia-Hua (3); Ma, Mei-Ling (4) 2010, 31 (4):  581-584.  DOI: - Abstract ( 268 )   HTML   PDF (554KB) ( 580 )   Coupling the system dynamics with multi-objective planning (SD-MOP), a relevant model was developed taking account of their respective advantages and disadvantages. Then, the Changshu city was taken as an instance to which an optimization analysis was made systematically and dynamically. In the analysis the five sub-systems including economy, population, resource, space and ecology were taken as cores to give a cause-effect feedback graph for the city size. With the city's population and per capita living space taken as reference objects, the conformity and sensibility tests were carried out and verified that the SD-MOP model is stable with small error. Furthermore, taking the regulation coefficient of technologies, rate of land exploitation, improvement rate of ecological condition and increment of greening coverage rate as control parameters, the optimization analysis was made for the Changshu city size. References | Related Articles | Metrics

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Interfacial shearing force analysis based on variational principle for steel-concrete-steel sandwich panel Zhang, Xin-Cai (1); Liu, Xiao (1); Wang, Lian-Guang (1); Ruan, Hang (2) 2010, 31 (4):  585-588.  DOI: - Abstract ( 289 )   HTML   PDF (583KB) ( 477 )   Based on the variational principle, the differential equations are derived to calculate the interfacial shearing force of a steel-concrete-steel sandwich panel with a formula given to calculate the interfacial shearing force under uniformly distributed load. The calculated results show that the mid-span shearing force is maximum, and it decreases nonlinearly along the span gradually and approaches zero at the end. On the other hand, the interfacial shearing force increases with the stiffness of connections between the two steel plates and external load but decreases with the increasing steel content of the board and concrete strength. The main influencing factors on the interfacial shearing force are the stiffness of connections and external load. References | Related Articles | Metrics

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On the axial-load bearing capacity of short steel tube column reinforced with structural steel and concrete Liu, Xiao (1); Wang, Lian-Guang (1); Wang, Bing (2) 2010, 31 (4):  589-592+608.  DOI: - Abstract ( 297 )   HTML   PDF (822KB) ( 625 )   To investigate the mechanical properties of the newly-developed heavy-load short steel tube column reinforced with structural steel and concrete, the stress states of the three different components of the column were analyzed according to the nonlinear relationship between concrete's compression resistance and side pressure. Based on the ultimate equilibrium theory, the ultimate cross-section bearing capacity formula of the column under axial-load was given. Moreover, the main influencing factors on increasing the axial-load bearing capacity were analyzed to determine the relationships between the stress of different components and hoop confining index. The calculated results conform highly with the tested values as shown in earlier works. The hoop confining index and steel quantity used in the column play indispensable roles in enhancing the axial-load bearing capacity, which offers a theoretical basis to the design in engineering applications. References | Related Articles | Metrics

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Variability analysis of empirical formula of resistance to pile end on a manually dug hole bottom Wang, Li-Qun (1); Zhao, Wen (1); Li, Yi (1) 2010, 31 (4):  593-596.  DOI: - Abstract ( 299 )   HTML   PDF (1442KB) ( 569 )   It was found that the standard value of the resistance to pile end on a manually dug hole bottom, which was calculated by an empirical formula, is variable, and the variability consists of the uncertainties of the formula itself, pile end diameter and number of heavy-duty DPTs. The calculating formulae were derived according to random field theory and variance propagation law for the variability of the empirical formula itself and the empirical formula considering the self-correlation of the number of DPTs, with the statistical parameter of pile end diameter given. A numerical example showed that the heavy-duty DPT data are suitable to the calculation of correlated distance for the foundations of sand soil and gravelly soil, and each of the number of DPTs correlates to the other one. References | Related Articles | Metrics

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Method for uncertain linguistic multiple attribute group decision making with incomplete attribute weights Zhang, Yao (1); Fan, Zhi-Ping (1) 2010, 31 (4):  597-600.  DOI: - Abstract ( 406 )   HTML   PDF (188KB) ( 556 )   To solve the group decision making problems with uncertain linguistic multiple attributes and incomplete information on attribute weights, a decision analysis method was proposed. Describing the uncertain linguistic variables, the calculating steps were given to solve the group decision making problems, among which the core was to aggregate the uncertain linguistic decision matrices provided by experts to a group decision matrix with informative possibility. Then, a quadratic programming model was developed through calculating the deviation values between every alternative and positive/negative ideal point to determine attribute weights, thus giving the relative proximity of each alternative so as to rank all alternatives. A numerical example was given to illustrate how to use the proposed method and the analysis result showed that the method is simple, feasible and easy to perform. References | Related Articles | Metrics

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A model based on support vector machine for early warning financial crisis Wu, Dong-Mei (1); Zhu, Jun (1); Zhuang, Xin-Tian (1); Yang, Lin (1) 2010, 31 (4):  601-604.  DOI: - Abstract ( 314 )   HTML   PDF (183KB) ( 1147 )   Financial indicators and corporate governance variables were sieved separately to get representative variables via factor analysis, mean value test and correlation analysis. Then, an empirical analysis was done by support vector machine (SVM). The results showed that the SVM model is superior in predicting the financial bankruptcy risk to other methods. Comparing the SVM model with the model based on financial indicators, it is found that the model introducing corporate governance variables in it is more predictable, where the variables include the proportions of circulating shares, shares held by the biggest shareholders and share ownership concentration. This method is worthy of practical applications to a certain extent. References | Related Articles | Metrics

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Multifractal statistical description and its sources for time series of returns on futures price Yuan, Ying (1); Zhuang, Xin-Tian (1); Jin, Xiu (1) 2010, 31 (4):  605-608.  DOI: - Abstract ( 337 )   HTML   PDF (394KB) ( 842 )   According to the multifractal detrended fluctuation analysis, an investigation on the time series of returns on the copper and soy bean futures prices in China was done empirically. It was found that the time series of returns on both futures prices are characterized with the leptokurtic especially the multifractality and not distributed normally, thus indicating that a single-scale index is insufficient to describe the commodity futures price fluctuation. Furthermore, the cause of multifractality was analyzed and it was found that most multifractality of the data is due to different long-range correlations for either small or large fluctuation. This correlations result in the price return series to be a biased random walk, i.e. the stock market fails to reach the soft efficiency. References | Related Articles | Metrics