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15 October 2011, Volume 32 Issue 10 Previous Issue    Next Issue
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H∞ control of descriptor bioeconomic systems Zhang, Yue (1); Zhang, Qing-Ling (1); Zhang, Tie-Zhi (2) 2011, 32 (10):  1369-1373.  DOI: - Abstract ( 305 )   HTML   PDF (383KB) ( 592 )   H∞ control of a class of descriptor single-species bioeconomic models was studied with T-S fuzzy descriptor system control approache. According to the theory of mathematics, ecology and economics, a descriptor bioeconomic models was established with differential and algebraic equations. The singularity-induced bifurcation (SIB) and impulsive behavior of the bioeconomic model were researched with differential algebraic equations. T-S fuzzy descriptor model was constructed, and a H∞ controller for the T-S fuzzy descriptor system designed to eliminate the singularity-induced bifurcation and impulsive behavior, restrain the population change, make the model system stable and keep the cost energy within limited range. Numerical simulation illustrates the validity of the proposed controller. References | Related Articles | Metrics

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Decentralized H∞ filtering for interconnected time-delay systems Xiao, Xiao-Shi (1); Mao, Zhi-Zhong (1) 2011, 32 (10):  1374-1377.  DOI: - Abstract ( 278 )   HTML   PDF (1613KB) ( 959 )   For a class of interconnected time-delay systems, a linear filter was designed for each subsystem by using the output of the subsystem as the input of the designed filter. Based on Lyapunov-Krasovskii functional method, a delay-independent sufficient condition of the existence of the linear filter was obtained. For the convenience of the filter design, a decoupling algorithm was applied to transform the obtained sufficient condition into a linear matrix inequality (LMI) which can be easily solved. Furthermore, the filter design problem was changed to a convex optimization solving problem constrained by LMI to achieve good H∞ performances. A numerical example demonstrates the feasibility of the proposed filter design method. References | Related Articles | Metrics

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Aerological detection with outbreeding elitist genetic algorithm Li, Jian-Bao (1); Zhang, Tie (1) 2011, 32 (10):  1378-1381.  DOI: - Abstract ( 315 )   HTML   PDF (151KB) ( 664 )   According to the characteristics of the large number and complex and unpredicted trend on change of the aerological detection data, the outbreeding elitist genetic algorithm (OEGA) was presented by analyzing the behaviors of outbreeding elitist and adding the evolution of slave population. The B-spline was calculated with OEGA to fit the aerological detection data curve. Compared with the result of the B-spline fitting with the simple genetic algorithm, the outbreeding elitist genetic algorithm has stronger searching ability and higher converging efficiency. References | Related Articles | Metrics

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Network traffic prediction algorithm based on wavelet transform and combinational models Wei, Yong-Tao (1); Wang, Jin-Kuan (1); Wang, Cui-Rong (1); Zhang, Kun (1) 2011, 32 (10):  1382-1385+1389.  DOI: - Abstract ( 376 )   HTML   PDF (1147KB) ( 1216 )   For the multi-scale characteristic of network traffic, a prediction algorithm based on wavelet transform and combinational SARIMA model was introduced. The network history traffic was decomposed with wavelet method to analyze complex correlation structure of the network traffic. According to the periodicity and self-similarity of the traffic series under different time scales, different prediction models were selected for prediction. The resulted series was reconstructed with wavelet method to get the results of original traffic. Simulation results showed that the proposed method can achieve higher prediction accuracy than that of the similar prediction methods. References | Related Articles | Metrics

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Nulls control method based on semidefinite programming Liu, Fu-Lai (1); Sun, Chang-Yin (1); Wang, Jin-Kuan (1) 2011, 32 (10):  1386-1389.  DOI: - Abstract ( 291 )   HTML   PDF (401KB) ( 1121 )   The conventional adaptive beamforming algorithm can aim at the direction-of-arrival of jammer automatically. However when the antenna platform vibrates or the interference moves quickly, the mismatching between adaptive weight and data occurs due to the perturbation of the interference location. To solve the problems, a nulls control method based on semidefinite programming was presented to widen nulls of the adaptive antenna array. The method provides an improved robustness against the interference angle shaking and suppresses the interference signals and minimizes the mean output array SINR. Simulation results demonstrate its validity. References | Related Articles | Metrics

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Improved higher order convergent FastICA algorithm Ji, Ce (1); Hu, Xiang-Nan (1); Zhu, Li-Chun (2); Zhang, Zhi-Wei (2) 2011, 32 (10):  1390-1393.  DOI: - Abstract ( 419 )   HTML   PDF (1551KB) ( 1129 )   High order FastICA algorithms have the advantages of simple form and fast convergence rate. However, they are sensitive to their initial values affecting convergence effect and even resulting in inconvergence if the initial values are not chosen appropriately. To solve the problem, the FastICA algorithms of the third and fifth order convergence were improved with the steepest descent method. First, the initial values were calculated with the steepest descent method. Then, the optimal solution was calculated with the high order convergence FastICA algorithm. Speech signal separation experiments showed that the improved algorithm can separate mixed signal and overcome the initial value sensitivity problems effectively. References | Related Articles | Metrics

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Hybrid synchronization in unified chaotic systems with unknown parameters Liu, Hong-Juan (1); Li, Ya-Ling (2); Yu, Hai (1); Zhu, Zhi-Liang (1) 2011, 32 (10):  1394-1397.  DOI: - Abstract ( 278 )   HTML   PDF (1512KB) ( 614 )   A new type of hybrid synchronization was studied, in which some of the states are in-phase synchronous and the others are anti-phase synchronous. The hybrid synchronization in the unified chaotic systems with unknown parameters was mainly studied. A simple unidirectional linear controller and a parameter update law were designed to realize the hybrid synchronization between two unified chaotic systems with unknown parameters. Based on Lyapunov stability theory, a sufficient condition for hybrid synchronization was obtained analytically. When two different values of the parameter in the unified chaotic system were selected, numerical simulation results showed that the proposed controller can realize the coexistence of in-phase synchronization and anti-phase synchronization. The controller can be extended to some similar chaotic systems or hyperchaotic systems and has great value in real applications. References | Related Articles | Metrics

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Microstructure and properties of stainless steel clad plate by vacuum rolling cladding Xie, Guang-Ming (1); Luo, Zong-An (1); Wang, Guang-Lei (1); Wang, Guo-Dong (1) 2011, 32 (10):  1398-1401.  DOI: - Abstract ( 363 )   HTML   PDF (1318KB) ( 1255 )   6 mm thick stainless steel and 50 mm thick carbon steel were successfully combined by vacuum rolling cladding (VRC). Metallurgical bond of the clad interfaces was achieved by high vacuum, high temperature and severe rolling force to obtain the stainless steel clad plate with a high quality. In the clad interface, except small amount of fine and dispersed Si-Mn oxides, no crack and oxide layer were observed by optical microscope. Energy dispersive spectroscopy showed that Cr and Ni diffuse from stainless steel side to carbon steel side to form a rich Cr/Ni layer in the clad interface, leading to the increasing of hardness of the clad interface. The decarburization zone with lowest hardness is formed due to the migration of C from carbon steel to stainless steel. The shearing strength of the clad interface reaches to 467 MPa. References | Related Articles | Metrics

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Orientation characteristics of hot deformed duplex stainless steel under different strain rate Wang, Jia-Fu (1); Hua, Fu-An (1); Li, Jian-Ping (1); Wang, Guo-Dong (1) 2011, 32 (10):  1402-1405+1409.  DOI: - Abstract ( 374 )   HTML   PDF (1813KB) ( 589 )   Under 1000°C and strain rate range of 0.01~10 s-1, the hot compression test of super duplex stainless steels S32750 was carried out with MMS-200 thermal-mechanical simulator. EBSD(electron backscattering diffraction) technique was applied to analyze grain orientation and grain boundary characters. The results showed that the <111> texture appears in ferrite under lower strain rate, and the additional <001> texture appears under higher strain rate. The ferrite grains become finer and the number of small angle grain boundaries increases with the increasing of strain rate. The <110> texture appears in the deformed austenite under the strain rate of 10 s-1. The austenite grain size and the number of small angle grain boundaries increase with the increasing of strain rate. A lot of Σ3 twin boundaries appear in the deformed austenite under lower strain rate. References | Related Articles | Metrics

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Hot deformation behavior of high-purified 17%Cr ferritic stainless steel Gao, Fei (1); Liu, Zhen-Yu (1); Wang, Guo-Dong (1) 2011, 32 (10):  1406-1409.  DOI: - Abstract ( 291 )   HTML   PDF (1705KB) ( 772 )   The hot deformation behavior of high-purified 17%Cr ferritic stainless steel at strain rates from 1 s-1 to 10 s-1 and deformation temperatures from 600°C to 1100°C was investigated by Thermo-Calc thermodynamic calculation and MMS200 thermomechanical simulator. The results showed that the high-purified 17%Cr ferritic stainless steel presents a ferritic (α-Fe, bcc) microstructure without γ/α phase transformation and undergoes rapid dynamic recovery during the hot deformation. The high-purified 17%Cr ferritic stainless steel has activation energy of 384.985 kJ/mol for hot deformation. On this basis, Zener-Hollomon parameter can be determined and the correlation of Zener-Hollomon parameter with peak stress was obtained. References | Related Articles | Metrics

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Application of cyclo-converter in main drive system of hot strip mill Li, Zhen-Xing (1); Liu, Xiang-Hua (1) 2011, 32 (10):  1410-1413.  DOI: - Abstract ( 238 )   HTML   PDF (1040KB) ( 599 )   Under the background of the engineering project for Shougang 2160 hot strip mill, the digital vector control system of a cyclo converter-fed synchronous motor drive was investigated. The composition and main technical characteristics of main circuit and control system were expounded, and especially thyristor trigger and speed control researched. The speed control system with load observer was developed to solve poor dynamic character of load fluctuate. The research results have been used on site, the precision of speed control is better than 0.01%, and the dynamic respond time is less than 50 ms. References | Related Articles | Metrics

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Microstructure and thermal fatigue properties of high chromium cast steel roll Cao, Yan (1); Zhang, Jun-Tian (2); Wang, Wei (3); Liu, Xiang-Hua (1) 2011, 32 (10):  1414-1417.  DOI: - Abstract ( 289 )   HTML   PDF (1636KB) ( 677 )   The microstructure and properties of high chromium cast steel roll were studied to solve the serious thermal fatigue (TF) cracks in the surface of the roll. The relationship between TF cycles and main TF crack length was obtained by self-constrained TF tests and stretching tests at high temperatures. The mechanical properties at high temperatures were measured. The effect of microstructure and segregation on TF crack propagation was analyzed by SEM and EDS. The results showed that the route and manner of TF cracks initiation and propagation depend on the surface appearance of the roll. The speed of crack propagation is related to the high limit of temperature and heating speed of thermal cycles. In addition, TF performance is affected by the roll properties and microstructure change. References | Related Articles | Metrics

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Corrosion behavior of Mn-Cu weathering steel in simulated industrial atmosphere environment Wu, Hong-Yan (1); Du, Lin-Xiu (1); Liu, Xiang-Hua (1); Zhang, Xi (2) 2011, 32 (10):  1418-1422.  DOI: - Abstract ( 292 )   HTML   PDF (2592KB) ( 589 )   Corrosion evolution of Mn-Cu weathering steels in a simulated industrial atmosphere environment was studied by wet/dry cyclic accelerated corrosion test and electrochemical test. The results showed that the corrosion rate increases with the wet/dry cycles in the initial stage of the test and decreases in the latter stage of the test. The corrosion rate of weathering steel is near to SPA-H steel and lower than that of 16Mn steel. In the early, the corrosion rate of fine grain weathering steel is faster than that of coarse grain, and the corrosion rate is the same in the latter. Rust layer of weathering steel is divided into outer and inner layers, and the inner rust layer is dense and mainly composed of α-FeOOH and a little of γ-Fe2O3 composition. Grain size has little effect on the composition of corrosion products. Rust layer of 16Mn steel is composed of α-FeOOH, γ-Fe2O3 and Fe3O4 composition. The corrosion resistance of Mn-Cu steel is better than 16Mn steel in the late corrosion test due to Cu action. The polarization behavior of the rusted steel showed that the corrosion product promotes the cathodic process and restrains the anodic process. Fine grain is in favor of the rapid formation of protective rust layer, and the change of corrosion potential and corrosion current of fine grain weathering steel in polarization curve is bigger. References | Related Articles | Metrics

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Production process of DP700 steel with early ultra fast cooling Cai, Xiao-Hui (1); Liu, Xu-Hui (1); Liu, Zhen-Yu (1); Zhang, Zhi-Li (2) 2011, 32 (10):  1423-1425+1430.  DOI: - Abstract ( 397 )   HTML   PDF (1328KB) ( 607 )   The production process of source-saving hot-rolled dual phase (DP) steel on HSM-line with early ultra fast cooling (UFC) was investigated. The cooling process of DP steels with early UFC was proposed after large number of experiments in the laboratory and in steel plant. The results obtained from laboratory and the plant showed that tensile strength is more than 700 MPa, yield ratio is 0.51~0.60 and elongation is 22%~28% for the DP steel produced in steel plant. The proposed production process of DP700 steel with early UFC is feasible with no or less microalloy/alloy elements, which decreases the production cost and improves the welding property. References | Related Articles | Metrics

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Effects of deformation and boron on continuous cooling transformation of low carbon Mn-Nb steels Li, Yan-Mei (1); Duan, Zheng-Tao (1); Zhu, Fu-Xian (1); Zhang, Hui-Yun (1) 2011, 32 (10):  1426-1430.  DOI: - Abstract ( 307 )   HTML   PDF (4048KB) ( 588 )   The continuous cooling transformation (CCT) of low carbon Mn-Nb steels with/without boron was investigated by thermal-mechanical simulator. The CCT curves of two kinds of steel were obtained and the microstructures and microhardness of the samples with different cooling rate were measured. The results showed that deformation moves the CCT curves to the left, increases the transformation start temperature, and promotes the formation of polygonal ferrite and pearlite. A trace boron addition moves the CCT curves to the right, decreases remarkably the transformation start temperature, suppresses obviously the formation of polygonal ferrite and pearlite, decreases the cooling rate range of polygonal ferrite and pearlite, and increases effectively the microhardness of low carbon Mn-Nb steel. References | Related Articles | Metrics

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Microstructure and mechanical properties of Al-12.7Si-0.7Mg alloy joints welded by AC TIG welding He, Chang-Shu (1); Wang, Dong (1); Zhao, Gang (1); Zuo, Liang (1) 2011, 32 (10):  1431-1434+1439.  DOI: - Abstract ( 507 )   HTML   PDF (1594KB) ( 686 )   Hot extruded Al-12.7Si-0.7Mg alloy plates were welded by tungsten inert gas (TIG) welding method using imported ER4043 and ER4047 welding wire. The microstructures and mechanical properties of welded joints were studied by optical microscopy, microhardness test and tensile test methods. The results showed that weld beads are fairly good under the chosen welding parameters. The weld zone (WZ) is the typical casting structure formed during weld solidification. Coarsening of silicon phase was observed in the heat-affected zone (HAZ). The distribution of microhardness of the welded joints shows that the hardness gets maximum values in WZ, drops rapidly in fusion zone (FZ) and reaches to minimum values at HAZ. The tensile strength of the joints welded with either ER4043 or ER4047 welding wire reach more than 90% of the base material. References | Related Articles | Metrics

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Effects of electromagnetic stirring on solidification structure of Cu-6%Fe composite Deng, An-Yuan (1); Liu, Shi-Ming (1); Wang, En-Gang (1); He, Ji-Cheng (1) 2011, 32 (10):  1435-1439.  DOI: - Abstract ( 320 )   HTML   PDF (2764KB) ( 576 )   Electromagnetic stirring (EMS) was applied to improve solidification structure of Cu-6%Fe composite. The results showed that spherical Fe-rich precipitates are formed in the copper matrix, and the distribution of the precipitates is inhomogeneous. The electromagnetic stirring decreases the size of Fe-rich precipitates and Fe enriched regions. After applying electromagnetic stirring, the Fe-rich precipitates are accumulated towards the centre of the casting and distribute with agminate tendency. The Fe-rich precipitates with larger size mainly locate at the centre of casting, whereas the finer precipitates are near the outer surface of casting. With electric current increasing, the grain size gradually decreases, and the precipitates are refined and distribute more uniform simultaneously. Upon a further increase, the precipitates gradually accumulate to the centre from outer surface of the casting. A rational electric current can make the Fe-rich precipitates tend to distribute uniformly. In this case, the optimal EMS current is about 100~200 A. Also an optimal EMS frequency can make the grain finer, and an appropriate frequency is about 20 Hz in this case. References | Related Articles | Metrics

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Simulating metallurgical reactor with swirling flow driven by gravitational potential energy Wang, Fang (1); Liu, Zhong-Qiu (1); Yang, Wen-Chuang (1); Li, Bao-Kuan (1) 2011, 32 (10):  1440-1443+1459.  DOI: - Abstract ( 239 )   HTML   PDF (1884KB) ( 667 )   A mathematical model of the metallurgical reactor with swirling flow driven by gravitational potential energy was established to analyze the flow field and gas volume fraction. The results showed that the modeling results are basically consistent with the experimental results, thereby the reliability of the proposed model and the relevant computation program are verified. The reactor driven by gravitational potential energy can attain better swirling flow effect, and the swirling effect is the best when the vane has the form of forward bending. The gas volume fraction in the mixing tube increases greatly with increasing the curvature radius. When the curvature radius is 150 mm, some bigger bubbles appear in the vane reactor. References | Related Articles | Metrics

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Effect of pulverized coal injection with magnesite on blast furnace operation at anyang steel Guo, Xian-Zhen (1); Wei, Guo (1); Shen, Feng-Man (1); Niu, Wei-Jun (2) 2011, 32 (10):  1444-1447.  DOI: - Abstract ( 341 )   HTML   PDF (525KB) ( 567 )   The slag marking of No.7 BF of Anyang Steel was analyzed, and then injecting raw materials containing MgO into BF through tuyere was proposed to improve slag properties. Industrial tests of pulverized coal injection with light burned magnesite were carried out at No.7 BF of Anyang Steel. The results showed that the adverse effect of high Al2O3 on metallurgical properties of slag is remitted, and the production index of BF is improved. When the addition of light burned magnesite is 3%, and w(MgO)/w(Al2O3) is 0.60~0.65 in slag, the hot metal temperature is improved significantly, and the sulfur distribution coefficient increases. To ensure high efficiency and smooth operation of BF with pulverized coal injection with magnesite, the thermal system, slag forming, coke burden, and "heat balance of hearth gas" should be controlled properly. References | Related Articles | Metrics

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Residual stresses of plasma-spraying coating of thin-walled part Niu, Li-Ping (1); Zhang, Ting-An (1); Shi, Guan-Yong (1); Dou, Zhi-He (1) 2011, 32 (10):  1448-1451.  DOI: - Abstract ( 362 )   HTML   PDF (1358KB) ( 739 )   A concept of thin-walled and thick-walled parts was proposed for plasma-spraying coating parts, and a mathematical model based on superposition principle established to calculate residual stresses. The results showed that both tensile stress and compressive stress may arise in the coating. The limit value of residual stress appears in the combination zone of substrate and coating. The relaxation of residual stress was effectively estimated with layer model and stress superposition method. The experimental results agree with the calculated results. The effect of thermal expansion coefficient, preheating temperature of substrate and coating thickness on residual stress is great. These results may provide a valuable reference for the design of plasma spraying coating. References | Related Articles | Metrics

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Effect of MnO2 addition on sintering behavior and magnetic property of nickel ferrite spinel Du, Jin-Jing (1); Liu, Yi-Han (1); Yao, Guang-Chun (1); Zhang, Xiao (1) 2011, 32 (10):  1452-1455.  DOI: - Abstract ( 335 )   HTML   PDF (1393KB) ( 734 )   NiFe2O4 spinel samples with different mass fractions of MnO2 were synthesized by two-step solid phase sintering process. The morphology and phase transformation were examined by scanning electron microscopy, X-ray diffraction and DTA analysis, respectively. The sintering behavior and magnetic property were investigated by thermal expansion instrument and vibrating sample magnetometer, respectively. The results showed that MnO2 decomposes into MnO and Mn2O3, the crystalline structure of the ceramic matrix is still of NiFe2O4 spinel and no other new phases appear. MnO2 addition can promote sintering obviously, the temperature where maximum shrinkage rate is attained for 1% MnO2-doped samples is 59°C, lower than that for un-doped samples. The saturation magnetization and coercivity are 15.673 emu/g and 48.316 Oe, respectively for 1% MnO2-doped samples. References | Related Articles | Metrics

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Extracting bioleaching solution containing copper Tong, Lin-Lin (1); Yang, Hong-Ying (1); Liu, Chun-Ming (1) 2011, 32 (10):  1456-1459.  DOI: - Abstract ( 262 )   HTML   PDF (817KB) ( 674 )   The extraction efficiencies of three kinds bioleaching solutions containing copper (HTS, KLTK and LW) were studied using LIX984N as the extracting agent. The optimum condition of extraction is 2.5 of pH value, 3:2 of volume ratio of organic material to water, 20% of mass fraction of extracting agent, 3 g·L-1 of Cu2+ mass concentration of original extraction fluid, and 11 min extraction time. The experiment results indicated that the first stage extraction efficiency can reach above 99%, the first stage back extraction efficiency is above 95%, and the second stage back extraction efficiency is above 97%. The extraction efficiency is high. References | Related Articles | Metrics

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Double integration model for reliability computation of mechanical components at dependent failure modes Yan, Ming (1); Zhang, Yi-Min (1); Li, He (1); Tang, Le (1) 2011, 32 (10):  1460-1463.  DOI: - Abstract ( 309 )   HTML   PDF (947KB) ( 581 )   Supposing that three or more failure modes arise synchronously to be very small probability event, the relationship between limit state functions was established for different failure modes by using linear regression method. A double integration model was built for reliability calculation of mechanical components at dependent failure modes. The model can be used after a linear transformation if a square, cube or exponential relationship appears between the limit state functions. Pin reliability was computed at dependent failure modes by the model and validated by the Monte Carlo method. The result confirms the validity of the double integration model. References | Related Articles | Metrics

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Dynamic determination method based on cantilever resonance for IPMC Young's modulus Hao, Li-Na (1); Gao, Jian-Chao (1); Liu, Hong-Tao (1) 2011, 32 (10):  1464-1467.  DOI: - Abstract ( 314 )   HTML   PDF (1090KB) ( 995 )   A dynamic determination method based on cantilever resonance was presented to solve the crude and material-damage problems of current ways in measurement of IPMC Young's modulus. An incentive device was applied to bring the IPMC into the damping free vibration state, which was recorded by a laser displacement sensor. The fundamental frequency was obtained by analyzing and processing the collected signal. A transverse vibration equation was established on the basis of the cantilever resonant vibration, and the IPMC Young's modulus can be then calculated by introducing boundary conditions. Compared with the existing tensile and bending tests, the proposed method has advantages of convenience and simpleness, non-destructive testing and high measurement accuracy. References | Related Articles | Metrics

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Simulation and experiment of front crash of vehicle Zhang, Guo-Sheng (1); Wang, Wei (2); Chen, Ye (2); Zhang, Tian-Xia (1) 2011, 32 (10):  1468-1471.  DOI: - Abstract ( 314 )   HTML   PDF (1469KB) ( 1758 )   Taking a car as the object, a vehicle finite element model including the occupant restraint system was established. In LS-DYNA environment, the whole model was divided into 360, 000 shell elements for numerical simulation of the front crashing process. The energy transfer and dissipation, the energy absorption effect of the main structure and the deformation damage index of the driving dummy were analyzed. The comparison between the simulation and the crashing test confirms the effectiveness of the finite element model including the occupant restraint system. The proposed car collision model including the occupant restraint system and the computer simulation method reflect the status and the results of the real vehicle crash, which have some practical value in engineering application. References | Related Articles | Metrics

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Dynamic stability of open pit slope under blast loading Yang, Yu-Jiang (1); Li, Yan (2); Liu, Jian-Po (1); Xu, Shuai (1) 2011, 32 (10):  1472-1475.  DOI: - Abstract ( 232 )   HTML   PDF (977KB) ( 694 )   Based on the conditions of deep open pit of Guilaizhuang gold mine, the static safety factors of open pit slope were obtained by the FLAC software according to the principle of the strength reduction method. The explosive loading was imposed on the open pit bottom to analyze the dynamic stability of the slope under different reduction factor. The theory of load-unload response ratio (LURR) was introduced to establish a load-unload response model of slope under blast loading. The periodical variation of blasting vibration velocity was regarded as loading parameter, and the velocity of characteristic point was regarded as response parameter to determine the LURR of slope under blasting loading. It was found that the LURR under blast loading can reflect the different slope stability state, and the LURR increases gradually as the slope approaching instability. Therefore, LURR is regarded as a very effective nonlinear dynamic analysis method to judge slope stability. References | Related Articles | Metrics

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Rock damage process based on acoustic emission monitoring under cyclic loading Liu, Jian-Po (1); Li, Yuan-Hui (1); Yang, Yu-Jiang (1) 2011, 32 (10):  1476-1479.  DOI: - Abstract ( 258 )   HTML   PDF (1084KB) ( 654 )   Experimental studies on rock damage process based on acoustic emission (AE) technique were carried out under cyclic loading. On the basis of damage theory and load/unload response ratio theory, a mathematical model of the relationship between rock damage and AE numbers was established to study the rock damage process and the precursor of rock failure. The results showed that acoustic emission principles can reflect the rock damage process. Under cyclic loading, rock damage increases with stress level during the unload phase, but the Y value of acoustic emission load/unload ratio decreases gradually. For most rock specimens, the Y value reaches 1 and fluctuates in a small range when rocks reach the later phase of elastic deformation, which can be seen as a precursory characteristic to rock failure and this is meaningful to the forecasting of rock unstable failure under cyclic loading. References | Related Articles | Metrics

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Simulating directional hydraulic fracturing through coal seam drilling hole Fu, Xiang (1); Liu, Hong-Lei (1); Yang, Tian-Hong (1); Yang, Hong-Wei (2) 2011, 32 (10):  1480-1483.  DOI: - Abstract ( 270 )   HTML   PDF (1770KB) ( 691 )   Selecting on-site case of Jixi Chengshan coal mine as an engineering example, RFPA2D-Flow software was used to simulate the entire process of the directional hydraulic fracturing through coal seam drilling hole. The distribution and change of stress and water pressure were analyzed, with the formation and expansion of the damage and pressure relief zones studied. The gas drainage effect and gas pressure distribution during the gas drainage were contrastively studied before/after directional hydraulic fracturing through coal seam drilling hole. The results showed that the pressure relief zone between fracturing hole and controlling hole is the main channel for gas seepage after implementing directional hydraulic fracturing, thus the gas drainage effect is improved significantly. References | Related Articles | Metrics

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Mineralogical process of Lingyang iron ore Li, Yan-Jun (1); Wang, Yan-Ling (1); Liu, Jie (1); Zhu, Yi-Min (1) 2011, 32 (10):  1484-1487.  DOI: - Abstract ( 596 )   HTML   PDF (679KB) ( 859 )   Through the MLA automatic detection, XRD and other measurements, the detailed mineralogical process studies on the Lingyang iron ore in Jilin Province were carried out to identify the chemical composition, mineral composition, grain composition and dissemination characteristics of the ore. The results showed that iron mainly occurs in form of magnetite and siderite, and small amounts of iron exists in chamosite and berthierine. Lingyang iron ores are refractory due to complex composition, fine disseminated and iron minerals locking closely with gangue mineral. The results may provide the basic references for the rational exploitation of the iron ore resources. References | Related Articles | Metrics

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Resource-environmental pressure and efficiency of regional economy Wang, Qing (1); Wang, Feng-Bo (1); Gu, Xiao-Wei (1); Xu, Xiao-Chuan (1) 2011, 32 (10):  1488-1491.  DOI: - Abstract ( 323 )   HTML   PDF (1250KB) ( 606 )   The aggregate resource-environmental pressure and efficiency of a regional economy were presented. The resource-environmental pressure and efficiency of Shenyang from 1991 to 2005 were studied empirically. The results showed that the aggregate resource-environmental efficiency of Shenyang's economy increased by 7.4% at a year, and its efficiencies on the input and output sides increased by 8.1% and 11.4% at a year, respectively. This means that the environmental pressure (especially on the output side) per unit of economic output decreased at a relatively high speed. This is a great achievement for Shenyang in view of the fact that its economy is at a stage of fast industrialization. However, the environmental pressure increased by 11% at a year after 2000. About 60%~70% of the total pressure is from the output end and about 85%~97% of the output pressure is caused by CO2 emission from energy consumption. References | Related Articles | Metrics

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Water resources carrying capacity of Liaoning along Bohai region Li, Chuan (1); Wang, En-De (1) 2011, 32 (10):  1492-1494.  DOI: - Abstract ( 328 )   HTML   PDF (388KB) ( 752 )   Based on the review of existing calculation methods for analysis the water resources carrying capacity, the key industries of Liaoning Province along Bohai region were screened, and two plans that reflect farthest the local development wish for regional economic development of Liaoning along Bohai were designed in light of the national overall development vision. Needed water and available water were forecasted across the administrative area for economic development of Liaoning Province along Bohai region, with water resources carrying capacity of the region calculated. Water resources carrying capacity will be surplus according to economic development plans in 2015. However, the water resources carrying capacity will be overloaded according to the latter economic development plan in 2020, and water resource shortage is 520 million ton per year. References | Related Articles | Metrics

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Influence of FRP sheet length on failure process of reinforced concrete beam Zhang, Juan-Xia (1); Zhu, Wan-Cheng (2); Tang, Chun-An (2); Guo, Xian-Zhang (1) 2011, 32 (10):  1495-1498.  DOI: - Abstract ( 309 )   HTML   PDF (1409KB) ( 512 )   The stress transmission process in the FRP sheet was analyzed numerically during the failure process of the FRP reinforced concrete specimen, characterized as the stress initiation, propagation and final decay of the loading capacities. Based on the examination of the mechanical properties of reinforced concrete structures under different FRP sheet lengths, it was found that the ultimate strain and the toughness, as well as the loading capacity and tensile stress sustained by the FRP sheet, increase with the RFP sheet length, and more cracks are also distributed on the bottom of the beam. For the shorter FRP sheet, the debonding failure is prone to occurring. References | Related Articles | Metrics

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Treating and monitoring lacustrine soft soil subgrade at Yinchuan city ring road Zhang, Jun (1); Ma, Hong-Lin (1); Zhu, Fu-Sheng (1) 2011, 32 (10):  1499-1502+1516.  DOI: - Abstract ( 337 )   HTML   PDF (1647KB) ( 655 )   Through a subgrade treatment engineering example, lacustrine soft soil treatment method and settlement rules of Yinchuan city ring road were studied on the basis of the field monitoring. The results showed that the compression coefficient of the lacustrine soft soil is big, its bearing capacity is low, and it has a poor permeability, the soft soil must be treated before the construction of subgrade. Sand-gravel cushion, bag sand well and broken stone compaction pile are some effective methods to treat this lacustrine soft soil subgrade, and design of the subgrade treatment is reasonable and economical, construction procedure is suitable, and the experience from this engineering is valuable for some other similar projects. References | Related Articles | Metrics

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Ignition of magnesium powder dust layers at constant heated plate Yuan, Chun-Miao (1); Li, Chang (1); Li, Gang (1) 2011, 32 (10):  1503-1506.  DOI: - Abstract ( 498 )   HTML   PDF (1518KB) ( 617 )   The ignition processes of four types of magnesium powder dust layers at constant heated plate were investigated. In this respect, main concerns are temperature distribution inside magnesium powder layers at precritical, critical, and postcritical temperature of hot plate. The results showed that the ignition of magnesium dust layer would not occur at the maximum temperature of hot plate determined by standards GB/T 16430-1996 and IEC 61241-2-1-1994. The dust layer would come into a long-duration stable temperature after a short period of rising temperature. The critical temperature of hot plate and the ignition delay time increase with particle size. As the temperature of hot plate is larger than the critical one, the higher the temperature of hot plate is, the shorter the ignition delay time of dust layer is. References | Related Articles | Metrics

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Multi-attribute group decision-making with incomplete interval linguistic information Liang, Hai-Ming (1); Jiang, Yan-Ping (1) 2011, 32 (10):  1507-1511.  DOI: - Abstract ( 301 )   HTML   PDF (1514KB) ( 687 )   With respect to the multi-attribute group decision-making problem in which the attribute weights are linguistic variable and assessment information is incomplete interval linguistic information, a revised fuzzy interval evidential reasoning method was proposed. Firstly, the incomplete information was represented by random variables, and decision matrixes given by experts were combined into a credibility matrix according to the importance degrees of the experts. Then, the distributed assessment values of the alternatives were calculated by using the revised fuzzy interval evidential reasoning method. Further, fuzzy assessment values of all the alternatives were calculated to determine the alternative ranking result. Finally, a numerical example was given to illustrate the effectiveness of the proposed method. References | Related Articles | Metrics

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Effect of commercial banks competition on credit availability for small enterprises Qin, Jie (1); Zhong, Tian-Li (1) 2011, 32 (10):  1512-1516.  DOI: - Abstract ( 320 )   HTML   PDF (1559KB) ( 744 )   An analytic model on effect of commercial banks competition on credit availability of small enterprises was constructed to discuss whether the increase of commercial banks competition degree is favorable for the improvement of credit availability of small enterprises or not. In the model, the cost of switching bank of the enterprise was selected as an index to measure the commercial bank competition degree, and other four factors, i.e., enterprise income on investment projects, probability of success of enterprise projects, cost for advanced capital and differential interest rate set by banks according to the scale of enterprises, were also selected to measure the improvement of credit availability of small enterprises. The research results showed that loan risk of banks increases with the commercial banks competition, the loan to small enterprise ratio decreases, and intensified bank competition is not favorable for the increase of small businesses credit availability. Finally, the case of credit explosion of our country in 2009 was analyzed to verify the effectiveness of the proposed model. References | Related Articles | Metrics

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Prokaryotic expression, purification and bioactivity of chicken thymosin β4 concatemer Wang, Guo-Qing (1); Guo, Nong-Chao (1); Liu, Li (2) 2011, 32 (10):  1517-1520.  DOI: - Abstract ( 261 )   HTML   PDF (1385KB) ( 619 )   The Tβ4 concatemer (2Tβ4) was synthesized by constructing 2Tβ4 prokaryotic expression system. 2Tβ4 was purified and recombined using Ni-NTA spin column, and its immunocompetence was measured by MTT. Under the induction of 0.05 mmol/L IPTG, 6.7 mg 2Tβ4 per gram bacteria was obtained by expressing PET-32a(+)-2Tβ4 in competent cell BL21 (DE3). No significant differences were observed between the effects of 2Tβ4 and standard Tβ4 on the multiplication of lymphocyte. This proves the validity of the established chicken 2Tβ4 prokaryotic expression system, and provides basic material for the application of Tβ4. References | Related Articles | Metrics