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15 June 2012, Volume 33 Issue 6 Previous Issue    Next Issue
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Analysis and simple calculation method for thermodynamic properties of CCPP wet coal-gas Chu, Fei (1); Wang, Fu-Li (1); Wang, Xiao-Gang (1) 2012, 33 (6):  761-764.  DOI: - Abstract ( 660 )   HTML   PDF (488KB) ( 713 )   The calculating methods of the thermodynamic properties (TP) of combined cycle power plant (CCPP) wet coal-gas were analyzed which is used in the simulation of gas system. The results showed that wet coal-gas could be treated as ideal gas mixture reasonably and the common equations for the TP of ideal gas mixture were still valid if wet coal-gas pressure was below 732 kPa. The calculating error of the proposed method was small. The wet coal-gas was regarded as the mixture including dry coal-gas and water vapor, then the calculation process and common equations for the TP of wet coal-gas were discussed. The relationship between the fluctuations of the wet coal-gas composition, precipitation of water vapor, temperature fluctuations and the TP of wet coal-gas was analyzed based on the numerical computation. Finally, the handy calculation method of the TP of wet coal-gas was given, which could be used in the simulation of the CCPP coal-gas system under off-design conditions. References | Related Articles | Metrics

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A nonlinear adaptive modulation robust controller design for thyristor controlled series compensation Wang, Yan (1); Jing, Yuan-Wei (1); Zhao, Wei-Lun (2); Yang, Xiu-Min (3) 2012, 33 (6):  765-768+773.  DOI: - Abstract ( 521 )   HTML   PDF (486KB) ( 496 )   The robust control problem was studied for the single machine-infinite bus containing thyristor controlled series compensation (TCSC) power system with parameter uncertainties and external disturbances. Based on a nonlinear third-order model for a single machine-infinite bus system, two kinds of nonlinear controller were designed using backstepping methods. With backstepping, the origin nonlinear system does not need to be linearized and the closed-loop error system is guaranteed to be asymptotically stable. When damping coefficients is measured inaccurately, a dynamic feedback controller can be designed using adaptive backstepping containing the real-time estimation of uncertainty parameter. The design procedure revealed that the controller designed by backstepping possessed good performances. References | Related Articles | Metrics

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A new localization method of multiple sound sources based on microphone array Kim, Guang-Myong (1); Xie, Zhi (1); Zhang, Chuan-Yi (1) 2012, 33 (6):  769-773.  DOI: - Abstract ( 871 )   HTML   PDF (512KB) ( 949 )   In order to solve the problem that the traditional methods could not accurately measure the localization of multiple sound sources in far field, this paper presented a new multiple sound sources localization method, which could be used both in the near field and the far field. Two L-shape microphone arrays were used in the proposed method. In each array, signal's DOA was obtained by jointly estimating the DOA and frequencies of signals. Finally, locations of multiple sound sources could be estimated based on DOA's pair of two L-shape microphone arrays. The simulation examples indicated that locations of multiple sound sources could be accurately measured by the proposed method. By adjusting the distance between two L-shape microphone arrays, the standard deviation below 5% could be obtained, which showed the sound localization accuracy. References | Related Articles | Metrics

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The dry brush model of Chinese calligraphy based on iterated function system Zhang, Xi-Zhe (1) 2012, 33 (6):  774-777.  DOI: - Abstract ( 511 )   HTML   PDF (456KB) ( 747 )   Half-dry stroke is a kind of special effect of Chinese calligraphy during rapid moving dry brush. It is difficult to simulate because of the complex and random character. Based on the iteration function system, a novel dry brush model for calligraphy was proposed to simulate the random white effect in dry brush. This model constructed iterated function system based on user's brush speed and contrail, and rendered the attractor by chaos game algorithm as final dry brush stroke. Different from previous physics-based model, this model rendered half-dry stroke well for its random nature. References | Related Articles | Metrics

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Blind multi-user detection algorithm based on kernel independent component analysis Liu, Xiao-Zhi (1); Feng, Da-Wei (1); Yang, Ying-Hua (1); Qin, Shu-Kai (1) 2012, 33 (6):  778-781.  DOI: - Abstract ( 560 )   HTML   PDF (447KB) ( 527 )   For the problem of blind multi-user detection in the DS-CDMA system, an improved kernel independent component analysis (KICA) algorithm was proposed. First, fifth-Newton iteration method was introduced to the traditional FastICA algorithm, and then, a new kernel function-hybrid kernel function was used to solve the separation of nonlinear mixed signals. Based on the proposed algorithm, the multi-user signal detection was realized. At last, the proposed algorithm was compared with the traditional FastICA and KICA algorithms, and the simulation results showed that the improved-KICA algorithm had the smaller bit error rate and good convergent speed. References | Related Articles | Metrics

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Analysis of sensitivity characteristic and image reconstruction for brain magnetic induction tomography Chen, Yu-Yan (1); Wang, Xu (1); Lü, Yi (1); Yang, Dan (1) 2012, 33 (6):  782-785.  DOI: - Abstract ( 528 )   HTML   PDF (509KB) ( 600 )   To analyze the sensitivity of brain magnetic induction tomography (MIT), a simple three-shell concentric circular head model was presented. The influences of hematomas conductivity, hematomas area, hematomas location and skull conductivity on the induced voltage of receiving coil were discussed, and the reconstructed image was obtained by using variation regularization method for three different hematomas locations. Simulation results showed that low conductivity of the skull had little effect on the induced voltage of the receiving coil. The location and size of hematomas could be reflected by the reconstructed image using the variation regularization method. Compared with the Tikhonov regularization method, the quality of the reconstructed image obtained using the variation regularization method was enhanced. So an effective method for brain magnetic induction tomography was introduced. References | Related Articles | Metrics

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Design and development of a sitting and standing dual-purpose style ballistocardiography signal detecting system Wang, Chun-Wu (1); Wang, Xu (1); Long, Zhe (1); Zhang, Ke-Xin (1) 2012, 33 (6):  786-789+800.  DOI: - Abstract ( 574 )   HTML   PDF (543KB) ( 938 )   A sitting and standing dual-purpose ballistocardiography (BCG) signal detecting system was put forward and implemented. The high-precision A/D converter chip TM7708, the program-controlled scaling amplification technology and the digital filtering technology to detect BCG signals were adopted in the system. By using wavelet analysis for the noise elimination, the characteristic waveform was extracted, and at last, the heart rate can be detected automatically through VB software programming. The system was tested by using 30 healthy people as samples. These BCG signals were compared with the single-channel electrocardiosignal acquired synchronously. The results showed that the two kinds of signals were synchronous. The accuracy of the heart rate detection was about 98.2%. It verifies the feasibility of the developed system. The portable system can automatically detect the BCG signals of the subjects at any time, which will provide a reference for the extraction and analysis of heart and respiratory signals. References | Related Articles | Metrics

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New topological sort based on the design structure matrix Yuan, Hui-Lin (1); Wang, Ding-Wei (1) 2012, 33 (6):  790-792.  DOI: - Abstract ( 540 )   HTML   PDF (361KB) ( 863 )   A novel method was proposed that using the design structure matrix (DSM) to optimize the topological sort in the business processes. And the rule of operation based on adjacency matrix method was designed. By comparing the proposed method with that of the traditional method, the limitation to the loop was overcome. Because the calculation were carried out from two sides at the same time, it was more effective than the old method. These explorations for the application of the DSM in the optimization of business processes are positive. References | Related Articles | Metrics

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Nonlinear feature extraction in modeling of quality prediction and fault diagnosis Zhao, Jian-Zhe (1); Wang, Da-Ke (2); Li, Kai (2); Zhu, Zhi-Liang (1) 2012, 33 (6):  793-796.  DOI: - Abstract ( 613 )   HTML   PDF (499KB) ( 533 )   The features involved in modeling of quality prediction and fault diagnosis are in large number, complex and nonlinear, which makes the model compute in higher dimensions and time complexity, as well as a bad accuracy. To solve the above problems, a feature extraction method based on kernel principal component analysis (KPCA) and rough set (RS) was proposed. First, the features were extracted by the KPCA, and then reduced by the RS. Principle and specific implementation steps of the proposed method were introduced. In the end, simulations were carried out based on the operation process of tin bath in a glass manufactory, and SVM based model was established using the data captured in factual production as input. The features extracted from KPCA, RS and the proposed method were input into SVM models. The experimental results were compared with one another, which showed that the features extracted from integrated method of KPCA and RS were better than the others. References | Related Articles | Metrics

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Construction and analysis of web services complex network based on composite services Zhu, Zhi-Liang (1); Qiu, Yuan-Yuan (1); Li, Dan-Cheng (1); Wang, Xiao-Ming (1) 2012, 33 (6):  797-800.  DOI: - Abstract ( 524 )   HTML   PDF (472KB) ( 514 )   The approach to build a complex network of web service was proposed. The Web services were used as nodes of the complex network in this method, and invocation relationship between Web services were regarded as the edges of the complex network. Service relationship of the Web service composition structure was researched by the network model. The key Web services were found in the numerous Web services, and at the same time the robustness and reliability of composite services had been enhanced. The experimental results indicated that the method was correct and effective, while the proposed approach was helpful to shift the research of Web services from the traditional SOA model to a complex network model. It is also instructive for further research on Web service composition. References | Related Articles | Metrics

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A SaaS software lifecycle deducing model based on roles and interactions Song, Jie (1); Li, Tian-Tian (1); Jia, Lu-Lu (1); Zhu, Zhi-Liang (1) 2012, 33 (6):  801-805.  DOI: - Abstract ( 585 )   HTML   PDF (538KB) ( 481 )   This paper deduced a SaaS software lifecycle model based on roles and their interactions. The elements and basic roles of SaaS software ecosystem were firstly proposed. Secondly, the model of roles and their interactions in SaaS software lifecycle was defined. And thirdly, the optimized interaction path from many simulated paths was selected and adjusted. Then based on the optimized paths, the approach of simulating lifecycle was designed, including the selection of interactions and interacted time. Finally, the phrases of lifecycle by clustering the interactions on timeline were deduced. Theories and experimental results indicated that the proposed approach could properly deduce the SaaS software lifecycle model. References | Related Articles | Metrics

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Research on RFID composite events detection based on improved Rete algorithm Xu, Jiu-Qiang (1); Lu, Suo (1); Liu, Da-Peng (1); Kong, Qiu-Shi (1) 2012, 33 (6):  806-809+814.  DOI: - Abstract ( 521 )   HTML   PDF (523KB) ( 672 )   A RFID composite events detection method based on rules engine was presented, which separated the expressions of composite events rules from corresponding code since present methods bind them together tightly and lead to bad scalability for application system. Since traditional rules engine method-Rete method always cache many partial matching results, while RFID data is usually constrained with time, an outdated data collection mechanism based on the life cycle of the partial matching was proposed to delete those expired partial matching segments in order to reduce the pressure of the Rete rule network. Simulation test result showed that the improved algorithm effectively relieved the pressure of the Rete rule network and was more appropriate for RFID composite events detection. References | Related Articles | Metrics

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MAC layer superframe redesigning in wireless sensor network He, Xuan (1); Zhao, Hai (1); Zhu, Jian (1); Li, Da-Zhou (1) 2012, 33 (6):  810-814.  DOI: - Abstract ( 766 )   HTML   PDF (537KB) ( 622 )   Due to the energy of WSN node is so limited, sharing the channel fairly for every node can extend network life. On the basis of theoretical analysis, the structure of IEEE 802.15.4 superframe was redesigned for lack of the current superframe. In order to reduce the conflicting probability among nodes, sub-area competition and slotted scheduling were involved, and feature parameters to measure the network fairness index were put forward. Experimental results indicated that the proposed method effectively solved the problem of unfair channel contention under traditional CSMA/CA mechanism and reduced the max backoff times and cache occupancy rate, which balanced the distribution of network energy to extend the network life. References | Related Articles | Metrics

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Surface nanocrystallization of 1Cr18Ni9Ti stainless steel induced by shear deformation Mo, Cheng-Gang (1); Liu, Gang (1); Wu, Bao-Lin (2); Zuo, Liang (3) 2012, 33 (6):  815-818.  DOI: - Abstract ( 557 )   HTML   PDF (492KB) ( 556 )   1Cr18Ni9Ti stainless steel sheet was treated by ball milling. The microstructural evolution induced by shear-stress along the depth was examined by using optical microscopy, X-ray diffraction and transmission electron microscope, respectively. The results showed that shear-stress can induce surface nanocrystallization in 1Cr18Ni9Ti sheet. The grain refinement procedure is summarized as follows: the formation of dislocation cells through the propagation, slip, annihilation and recombination of the dislocations in the austenite matrix; the transformation of dislocation walls into small and large angle boundaries to refine the initial coarse grains into submicro-grains; the strain-induced mechanical twinning and nano-scale lamellar martensite; further subdivision of refined grains by dislocation activities and mechanical twinning leading to the formation of equiaxed nanoscale grains with random orientations. The direction of external loads does not affect the grain refinement procedure, but can change the thickness of deformation layer. References | Related Articles | Metrics

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Investigation on hot workability behavior of TWIP steel Zhang, Zhi-Bo (1); Zhang, Wei-Na (1); Liu, Zhen-Yu (1) 2012, 33 (6):  819-822.  DOI: - Abstract ( 536 )   HTML   PDF (482KB) ( 549 )   The hot deformation behavior of Fe-Mn-C twinning induced plasticity (TWIP) steel was investigated by hot compression tests in the temperature range of 800~1000°C and strain rate range of 0.01~10 s-1. Experimental results showed that increasing the temperature and decreasing strain rate promote the occurrence of dynamic recrystallization of austenite. According to the experimental flow stress curves, the hot working equation is obtained and the activation energy for plastic deformation is Q=421.37 kJ/mol. The occurrence of dynamic recrystallization can be estimated by using a Zener-Hollomon type equation and metallographic examination. Dynamic recrystallization is prone to occur when Z&le9.94×1018. The better hot deformation properties will be obtained under this condition. References | Related Articles | Metrics

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Microstructures and mechanical properties of low carbon Nb-B bainitic steel with different processing Duan, Zheng-Tao (1); Li, Yan-Mei (1); Zhu, Fu-Xian (1); Fan, Zhong-Mian (2) 2012, 33 (6):  823-826+847.  DOI: - Abstract ( 603 )   HTML   PDF (678KB) ( 614 )   The microstructures and mechanical properties of a low carbon Mn-Nb-B bainitic steel were investigated. The results revealed that when the finish rolling temperature is 850°C, the cooling rate is about 10°C/s and the stop cooling temperature is 560°C. The microstructure of tested steel is quasi-polygonal ferrite and granular bainite. The yield strength, tensile strength, impact energy (-20°C) and elongation are 495 and 720 MPa, 159 J, 23%, respectively. As the stop cooling temperature is decreased to 480°C, the yield strength and tensile strength are increased 51 MPa and 93 J respectively. The yield strength is increased 24 MPa when the finish rolling temperature is decreased to 810°C. When the cooling rate is increased to 25°C/s, the microstructure is composed of granular bainite, acicular ferrite and lath bainite. The yield strength, tensile strength, impact energy (-20°C), elongation are 655 and 777 MPa, 226 J, 20%, respectively. The substructure can be refined by accelerated cooling. The strength of tested steel can be increased observably through the substructure strengthing and the existence of lath bainite. References | Related Articles | Metrics

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Flow stress feature of DC cast Al-15Si alloy under hot compression deformation Wang, Chun-Xia (1); Yu, Fu-Xiao (2); Zhao, Xiang (1); Zuo, Liang (1) 2012, 33 (6):  827-831.  DOI: - Abstract ( 558 )   HTML   PDF (522KB) ( 512 )   The flow behavior of Al-15Si alloy during hot compression deformation was studied by isothermal compression test using Gleeble-1500 thermal-mechanical simulator in the temperature range of 300~500°C and strain rate range of 0.001~5 s-1. The results showed that the flow stress is controlled by both strain rate and deforming temperature. The flow stress decreases with increasing deforming temperature and increases with increasing strain rate, indicating that Al-15Si alloy is a positive strain rate sensitive material. The flow behavior of Al-15Si alloy during high-temperature deformation could be represented by hyperbolic sinusoid function of Zener-Hollomon parameters. Structure factor A, stress level parameter α and stress index n in the analytical expressions of σ are 2.07×1012 s-1, 0.026 MPa-1, 4.61, respectively. The activation energy of the alloy for hot deformation is calculated to be 180.96 kJ/mol. References | Related Articles | Metrics

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Grain refinement of AZ91D magnesium alloy and its effect on the partially remelted semi-solid microstructure Zuo, Yu-Bo (1); Zhao, Zhi-Hao (1); Wang, Gao-Song (1); Cui, Jian-Zhong (1) 2012, 33 (6):  832-835.  DOI: - Abstract ( 528 )   HTML   PDF (545KB) ( 451 )   Grain refinement of AZ91D alloy with intensive melt shearing and its effect on partially remelted semi-solid microstructure were studied. The results showed that the intensive melt shearing prior to solidification has a significant grain refining effect on AZ91D alloy, which can reduce the grain size of ingots cast at 650°C from 500 μm to 170 μm and further to 60 μm when the melt is treated at lower temperature. The initial microstructure plays a very important role on the formation of partially remelted semi-solid structure. The grain refinement achieved by the intensive melt shearing can be remained after partial remelting. Under identical reheating conditions, the uniform and fine microstructure can result in higher effective liquid fraction and more spherical microstructure. References | Related Articles | Metrics

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Study on decarburization process in RH degasser with side-bottom blowing Geng, Dian-Qiao (1); Lei, Hong (1); He, Ji-Cheng (1) 2012, 33 (6):  836-839.  DOI: - Abstract ( 689 )   HTML   PDF (483KB) ( 493 )   Based on the flow field in RH degasser, the metallurgical reaction thermodynamics and kinetics, a mathematical model was developed to investigate the decarburization process in RH degasser with side-bottom blowing. The numerical results indicate that the predicted results agree well with the experimental data. Under the condition of the same blowing gas flow rate, the decarburization rate in the first twenty minutes in RH with side-bottom blowing is greater than that in traditional RH. For decarburization in traditional RH, the decarburization in the inner site of the vacuum chamber accounts for the majority of the removed carbon in the first three seconds, while the decarburization rate at the surface of argon bubbles accounts for the majority of the removed carbon during three to one thousand seconds. For decarburization in RH with side-bottom blowing, the decarburization rate at the surface of argon bubbles accounts for the majority of the removed carbon in the first one thousand seconds, and decarburization rate at the surface of argon bubbles is as high as about two times of that in the inner site of the vacuum chamber. The production efficiency of ultra low carbon steel can be improved by increasing decarburization rate during final RH treatment. References | Related Articles | Metrics

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Study on surface area of raceway in COREX melter-gasifier Luo, Zhi-Guo (1); Sun, Jun-Jie (1); Di, Zhan-Xia (1); Zou, Zong-Shu (1) 2012, 33 (6):  840-843.  DOI: - Abstract ( 616 )   HTML   PDF (440KB) ( 527 )   The surface area of raceway has great influence on the heat and mass transfer in raceway. Based on the physical simulation of COREX melter-gasifier, the Euclidean and the fractal theory are applied to determine the surface area of raceway. The results show that the surface area determined by fractal method is greater than that by Euclidean method. The surface area of raceway increases with the increasing of blast volume and discharging rate, while it decreases with the increasing of bed packing height. References | Related Articles | Metrics

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Boundary determination of raceway in COREX melter gasifier Luo, Zhi-Guo (1); Sun, Ye (1); Zou, Zong-Shu (1); Chen, Ren (2) 2012, 33 (6):  844-847.  DOI: - Abstract ( 597 )   HTML   PDF (489KB) ( 453 )   A three-dimensional semicircular cold model of COREX melter gasifier was established for physical simulation. The particle motion information in the raceway was obtained by using high-speed photography to track the particle motion. The particle velocity scalar field was obtained through processing the data of particle motion information. The irregular degree of raceway boundary determined by the iso-velocity contour was discussed. The boundary of raceway is thereby determined precisely. The results can provide precise boundary conditions for macro kinetic calculation of raceway and numerical simulation. References | Related Articles | Metrics

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Simulation of burden charging for COREX-3000 shaft by discrete element method Li, Qiang (1); Liu, Dong-Liang (1); Zhang, Li-Juan (1); Zou, Zong-Shu (1) 2012, 33 (6):  848-851.  DOI: - Abstract ( 511 )   HTML   PDF (496KB) ( 653 )   The distribution of reducing gas in the shaft furnace of COREX-3000 influences directly the gas utilization ratio, the metallization degree of directly reduced iron and the burden descent. The charging of burden is the main means for regulating the gas flow distribution. A mathematical simulation model of burden distribution for COREX-3000 shaft was developed by discrete element method, and the model parameters were determined. The change of particles velocity and particles distribution in the process of burden charging, as well as the surface profile and inner structure of the bed, were analyzed at particulate-scale. The simulation results show that the small radius, heavy mineral particles tend to go through the surface layer consisted of the light and large size of fuel particles, thus it seems to make large particles enriched in the surface of heap. References | Related Articles | Metrics

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Research progress in structure and properties of medium- and high-temperature proton conductors Li, Ying (1); Ding, Yu-Shi (1); Wang, Chang-Zhen (1) 2012, 33 (6):  852-856.  DOI: - Abstract ( 722 )   HTML   PDF (605KB) ( 1053 )   Medium-and high-temperature proton conductors with perovskite structure have got much attention due to their good application prospects. Some proton conductors were introduced, which have been mostly studied nowadays, and the structures, characteristics and electric conduction mechanism of perovskite-type proton conductors were described. The chemical stability, strength and conductivity of all kinds of proton conductors were compared. The methods of preparation and characterization of proton conductors were also described. The effect of different doping elements on the proton conductivity and the stability of the perovskite-type oxides were analyzed, and the methods for improving the properties of proton conductors were summarized. The latest research results both at home and abroad are introduced. The focal points of research were presented as improving the traditional proton conductors, developing new type proton conductors and improving the preparation technology, in order to improve the stability and conductivity and expand the work temperature range of proton conductors. References | Related Articles | Metrics

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Column bioleaching of low-grade primary gold ore Ma, Peng-Cheng (1); Yang, Hong-Ying (1); Han, Zhan-Qi (1) 2012, 33 (6):  857-861.  DOI: - Abstract ( 683 )   HTML   PDF (567KB) ( 516 )   S-11 adhesive was used to paste gold concentrate around low-grade primary ore and the column bioleaching was compared with traditional column bioleaching. The concentration of Fe2+, pH, Eh, attached bacteria concentration on the surface of ore, free bacteria concentration in leaching solution, oxidation rates of arsenic and sulfur and cyaniding leaching efficiency were measured. The results show that it is better for bacterial reproduction when a coating of gold concentrate is pasted on the low-grade primary ore. The oxidation rate of arsenic is 70.14%, oxidation rate of sulfur is 41.26%, and cyaniding leaching efficiency is 81.21% after 120 days by column bioleaching. The rates are 24.01%, 19.11% and 21.48% higher than traditional column bioleaching, respectively. References | Related Articles | Metrics

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Enrichment of ferronickel from carbon-bearing laterite nickel ore pellets Liu, Yan (1); Xu, Dong (1); Zhang, You-Ping (2); Zhai, Yu-Chun (1) 2012, 33 (6):  862-865+903.  DOI: - Abstract ( 639 )   HTML   PDF (540KB) ( 465 )   Ferronickel alloy was prepared by magnetic separation and smelting after carbon reduction. The effects of the additive dosage, reduction temperature and time on the enrichment of ferronickel alloy were investigated. Under the conditions of additive dosage of 5%, carbon addition of 3%, reduction temperature of 1320°C and reduction time of 120 min, the contents of Ni and Fe in the magnetic product are 8.31% and 71.5%, and the yields of Ni and Fe are 95.44% and 99.84%, respectively. After smelting, ferronickel alloy with Ni and Fe content of 10.11% and 83.75% was obtained. The analysis of the enriching processes with and without additive show that the home-made additive accelerated and promoted the growth of ferronickel alloy. References | Related Articles | Metrics

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Effect of ZrO2 content on the density of nNaF·AlF3-Al2O3- CaF2 molten salt system Bao, Morigen-Gaowa (1); Wang, Zhao-Wen (1); Gao, Bing-Liang (1); Shi, Zhong-Ning (1) 2012, 33 (6):  866-869.  DOI: - Abstract ( 3104 )   HTML   PDF (439KB) ( 625 )   The density of nNaF·AlF3-Al2O3- CaF2-ZrO2 molten salt system with different molar ratio of NaF to AlF3 and ZrO2 contents was determined based on Archimedes law, and the effects of temperature and ZrO2 content were investigated. The results show that the density decreases with the increasing of temperature and the decreasing of molar ratio of NaF to AlF3. At 980°C, there is a good linear relationship between the density of 2.4NaF·AlF3-3wt%Al2O3- 3wt%CaF2 molten salt system and the ZrO2 content of 0~5wt%, which can be expressed as ρt(g·cm-3) = 0.02844·w(ZrO2)+2.045 (r=0.9992). Within the present study range, the electrolyte density increases approximately by 0.02 g/cm3 with 1wt% ZrO2 addition. References | Related Articles | Metrics

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Inverse kinematics algorithm for 6-DOF robots with offset wrist based on offset compensation Liu, Zhi-Zhong (1); Liu, Hong-Yi (1); Luo, Zhong (1); Wang, Fei (1) 2012, 33 (6):  870-874.  DOI: - Abstract ( 1111 )   HTML   PDF (528KB) ( 1276 )   Generally, there are no practical closed-form inverse kinematics solutions for 6-DOF serial robot manipulators with offset wrist. According to the geometric characters of the wrist offsets, based on the corresponding spherical wrist manipulator, numerical solutions for the manipulators with offset wrist can be obtained by complementally translating and iteratively correcting its wrist position. The algorithm does not affect the end orientation. Position errors are directly used to control the iterative process, so the numerical solutions can be evaluated to arbitrary precision. In the process, all joint variables are always computed by using the closed-form solutions of the corresponding spherical wrist manipulator, thus the codes are versatile. A large number of tests confirms that the algorithm can meet the requirements of real-time control. References | Related Articles | Metrics

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Surface quality evaluation of strip steel based on client application Dong, De-Wei (1); Yan, Yun-Hui (1); Li, Jun (1); Zhang, Yao (1) 2012, 33 (6):  875-878.  DOI: - Abstract ( 587 )   HTML   PDF (434KB) ( 563 )   The surface quality of strip steel is a very important aspect of strip steel quality. The traditional method of surface quality evaluation only considers the number and the level of defects, with regardless of the defect distribution which is closely related with the client application. This paper presents a linear programming model under the conditions of client application and the defect distribution data, then the strip utilization with and without surface defects are obtained, and their ratio can be used as a standard in testing the strip surface quality. This method avoids the limitations of the traditional quality evaluation which can't reflect the client application, ensuring the scientificity and practicality of the surface quality evaluation. The example indicates that the proposed method is feasible, effective and has a certain application. References | Related Articles | Metrics

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Digital analysis of hybrid bearing spindle system based on FEM Guan, Peng (1); Wang, Xue-Zhi (1); Yu, Tian-Biao (1); Wang, Wan-Shan (1) 2012, 33 (6):  879-882.  DOI: - Abstract ( 712 )   HTML   PDF (495KB) ( 732 )   The supporting characteristics of the hybrid bearings and the dynamic characteristics of the spindle system have a direct impact on the quality of grinding process. The dynamic characteristics of the spindle system are mainly dependent on the supporting stiffness and damping of the hybrid bearing. First, the oil film load capacity and temperature fields of the hybrid bearings are analyzed by using CFD method under different parameters, and the supporting stiffness and damping are then obtained with the "Moving Grid" technology. The results are then received into the equivalent stiffness and damping model, which is used in the finite element analysis of the dynamic characteristics of the spindle system. Finally, the natural frequency of the spindle system is measured to verify the validity of the analysis method. References | Related Articles | Metrics

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Method for generating automated exploded view based on ant colony algorithm Xing, Yu-Fei (1); Wang, Cheng-En (1); Yu, Jia-Peng (1) 2012, 33 (6):  883-886.  DOI: - Abstract ( 653 )   HTML   PDF (510KB) ( 955 )   A method of automatic acquiring exploded view was proposed. The ant colony algorithm was utilized to reduce the complexity of calculation. The computing method of exploded distance and the construction process of exploded view were presented. The connection matrix was used to evaluate the continuity of exploded view. The exploded view was optimized concerning with the changing frequency of the exploded direction, continuity and distance. Finally, with comparison of the automatic exploded view generated from UG NX, a reducer 3D model was studied to prove the validity and feasibility of the method. References | Related Articles | Metrics

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Pressure variation at ore pass bottom during ore drawing process Jin, Chang-Yu (1); Jin, Qi-Ling (2); Jiang, Quan (3) 2012, 33 (6):  887-890.  DOI: - Abstract ( 580 )   HTML   PDF (472KB) ( 554 )   The Janssen equation has been used to calculate the pressure variation at ore pass bottom during ore drawing process. However, the result calculated with the Janssen equation is usually larger than the practical one. According to the numerical analysis and laboratory tests, it is found that the pressure at the bottom maintains a certain value and it does not changes with the ore body height in the drop shaft. Based on the laboratory test data, the formula used to calculate the pressure at the bottom under the third kind of static pressure condition during ore drawing process is proposed. Comparing with the laboratory test results, the formula can well predict the pressure at the bottom of the ore pass and it provides the referential research basis for the flow patterns of the ore body during its drawing process. References | Related Articles | Metrics

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Experimental study on stope rockburst control in Erdaogou Gold Mine Ren, Feng-Yu (1); Ding, Hang-Xing (1); Ren, Guo-Yi (2); Liu, Zhong-You (2) 2012, 33 (6):  891-894.  DOI: - Abstract ( 632 )   HTML   PDF (466KB) ( 451 )   There are three steeply inclined and extremely thin ore bodies sub-parallel to each other in Erdaogou Gold Mine, which can be caved by the methods of resuing stoping and short-hole shrinkage. As the mining goes deeper, rockburst occurs more frequently, which has seriously affected the mining production already. According to the investigation and analysis of rockburst-prone stopes, three major necessary conditions leading to rockburst were summarized, namely high stress in the rock mass, high strain energy accumulated and sudden energy release. It was also revealed that the primary cause for high stress was the additional force caused by the wedge of hanging wall. Furthermore, the scheme of stope rockburst control by distressing was proposed and put into experiment, and the experimental results show that distressing by caving has a remarkable effect on rockburst control for this kind of rockburst-prone stopes for normal caving. References | Related Articles | Metrics

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Effects of rubber aggregate on the frost resistance of concrete Xu, Jin-Hua (1); Feng, Xia-Ting (1); Chen, Si-Li (2) 2012, 33 (6):  895-898.  DOI: - Abstract ( 568 )   HTML   PDF (495KB) ( 595 )   Rubber concrete specimens, made by mixing rubber with two types of grain size and four contents to replace the fine aggregate in the Portland cement concrete, were used for quick freeze-thaw test. This study focused on the durability of rubber concrete under freeze-thawing cycle conditions, which confirms that the concrete strength and dynamic elasticity modulus decrease with the increasing rubber content. It is also found that, appropriate proportion of fine aggregate replaced by the discarded tires powder and grain could improve concrete durability under freeze-thaw actions and the mixture of rubber powder show better performance than that of rubber grain. Especially, mixing 5%~10% rubber powder into concrete can improve resistance to frost obviously, however, the adverse effect for too much rubber is also found. The results reveal that dynamic elasticity modulus can make an accurate assessment to frost resistance of rubber concrete according to non-destructive testing. References | Related Articles | Metrics

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Assessment to capability of emergency management of enterprise based on AHP Tong, Shu-Jiao (1); Zhang, Pei-Hong (1); Zhong, Mao-Hua (2); Chen, Bao-Zhi (1) 2012, 33 (6):  899-903.  DOI: - Abstract ( 534 )   HTML   PDF (532KB) ( 590 )   Firstly, the key elements of emergency management such as precaution, preparedness, response and recovery are introduced. Secondly, the assessment index system for emergency management capability for major accident is built and the basic indexes of each element are confirmed too. Furthermore, based on AHP (analytic hierarchy process), the assessment model for ACEM (assessment to capability of emergency management) is built. And the quantitative computation is applied to the true enterprise and its true capability of emergency management is finally obtained. The study results could be useful to improve the emergency management scientifically, to prevent or control major accident, and to improve the management capability to major accident of enterprise. References | Related Articles | Metrics

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Fortification planning stochastic model and its algorithm for capacitated logistics systems Qin, Xu-Wei (1); Yu, Hai-Fei (1); Huang, Xiao-Yuan (1) 2012, 33 (6):  904-908+912.  DOI: - Abstract ( 458 )   HTML   PDF (715KB) ( 531 )   Vulnerability to sudden service disruptions caused by accidents is one of the major threats in existing logistics systems. This paper focused on capacitated logistics system under accidental disruptions and the two risk mitigation policies were proposed, viz. key facility protection and emergency inventory pre-positioning, to hedges well against accidental disruptions. A fortification planning model for capacitated logistics system was presented in a two-stage stochastic mixed-integer programming framework. The disjunctive decomposition-based branch-and-cut (D2-BAC) algorithm was developed which was used to solve the complicated model. The D2-BAC algorithm was improved by integrating with valid cuts and dynamical 'truncation' strategy of branch-and-bound tree. Extensive computational results confirmed the computational performance of the proposed method and the feasibility of the risk mitigation policies. References | Related Articles | Metrics

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Inventory cost control model in a supply chain under asymmetric information Li, Li-Jun (1); Wu, Xiao-Hui (1); Yan, Wei-Chao (1) 2012, 33 (6):  909-912.  DOI: - Abstract ( 459 )   HTML   PDF (492KB) ( 605 )   Being taken the impact of the information asymmetry on cost control in supply chain, a supply chain composed by a manufacturer and a retail was established. Supposing that the demand was time-related, in the two situations of information symmetry and information asymmetry, the whole profit situation of the manufacturer, the retail merchant and the supply chain was analyzed and the quantity discount coordinated mechanism was established accordingly. Research results showed that this reasonable coordination mechanism could effectively reduce the supply chain inventory cost. In the end, an example was made which illustrates the correlative conclusions. References | Related Articles | Metrics