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15 October 2008, Volume 29 Issue 10 Previous Issue    Next Issue
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Nonlinear model predictive control of evaporation process Wang, Yong-Gang (1); Chai, Tian-You (1) 2008, 29 (10):  1369-1372.  DOI: - Abstract ( 203 )   HTML   PDF (471KB) ( 705 )   The 6-effect countercurrent alumina evaporation process is actually a multivariable nonlinear system where the coupling between circuits is strong. A dynamic model is presented in the vicinity of the operating point in steady state, based on material balance and thermal equilibrium. Then, the NMPC strategy is applied to the simulation of the evaporation system to solve the NMPC optimization problem better. A genetic algorithm is introduced to calculate the control sequence, and the constraint on the output variables as penalty terms is added to the objective function to ensure the availability of the control quantities thus obtained. Comparing with the conventional PID control, the NMPC strategy can improve greatly the control performance and save energy to reduce its consumption. References | Related Articles | Metrics

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Design of multi-objective flight controller for an airplane with multiple operating points Shen, Chao (1); Jing, Yuan-Wei (1) 2008, 29 (10):  1373-1376.  DOI: - Abstract ( 204 )   HTML   PDF (1716KB) ( 513 )   The design of a multi-objective flight controller for an airplane with multiple operating points (MOP) is proposed via Lyapunov theory, which takes account of the requirement of handling quality and robust stability simultaneously with unknown system parameters. A criterion is derived by the linear matrix inequality (LMI) approach for all flights corresponding to multiple operating points. Based on the parameter-dependent Lyapunov functions in combination with a descriptor system, a robust stability condition is given for the flight control system. In this way the design of flight controller can be attributed to the solution to a set of LMIs. The simulation result verified the effectiveness of the design method proposed. References | Related Articles | Metrics

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Study on a new MOPSO and its applications Wang, Xiao-Gang (1); Li, Ming-Jie (1); Wang, Fu-Li (1); Hu, Lun (2) 2008, 29 (10):  1377-1380.  DOI: - Abstract ( 261 )   HTML   PDF (184KB) ( 795 )   To update the performance of the multi-objective optimization method, a new MOPSO (multi-objective particle swarm optimization) algorithm is proposed on the basis of earlier works relevant to particle swarm optimization and in combination with the optimization of a specific copper electrolysis process. Introducing the size-variable external data set and fast sorting to reduce the time for computation, both the congestion operator and strong predominance are used in the algorithm to provide a good diversity in its solutions. The new algorithm thus shows better convergence, solution diversity and computation efficiency especially the superiority in solving the three-objective optimization problems. All the advantages mentioned above are demonstrated by the simulation/comparison results of testing functions and the optimization of real data recorded in copper electrolysis process. The broader applicability in multi-objective optimization field of the proposed algorithm is thus proved. References | Related Articles | Metrics

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Control based on Wash-Out-Filter for Hopf bifurcation of nonlinear systems An, Yi-Chun (1); Zhang, Qing-Ling (1); Zhang, Yan (1); Su, Zhan (1) 2008, 29 (10):  1381-1384.  DOI: - Abstract ( 237 )   HTML   PDF (1122KB) ( 569 )   Hopf bifurcation frequently results in periodical oscillation even unstability. Therefore, based on wash-out-filter, a state feedback controller is designed for Hopf bifurcation of the nonlinear systems. With the equilibrium points remaining unchanged, the original subcritical Hopf bifurcation is transformed into supercritical one, which is thus ensured to be asymptotically stable in the range of expected parameters in controlled system. The 1-D and 2-D nonlinear systems are both exemplified to show the effectiveness of the propose method. References | Related Articles | Metrics

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Fast image mosaic based on wavelet transform for remote sensing Cheng, Yuan-Hang (1); Xue, Ding-Yu (1); Han, Xiao-Wei (2) 2008, 29 (10):  1385-1388.  DOI: - Abstract ( 282 )   HTML   PDF (275KB) ( 966 )   A method of serial fast image mosaic was put forward for the remotely sensed images provided from UAV (unmanned air vehicle), based on wavelet transform and matching of low-frequency images. According to the interior and exterior azimuthal elements of the remotely sensed imaging by UAV, the rectangular spatial transformation and second order linear interpolation are used to correct the images. The method proposed uses the wavelet transform to extract the low-frequency sub-images and search the relevant area, thus obtaining the characteristic image as template. Then, the SSDA (sequential similarity detection algorithm) is introduced to perform the image matching computation and after analyzing the result, two images are mosaiked together. Simulation results showed that the algorithm presented greatly improves the operation speed with high precision and that it can be applied to real-time mosaiking of serial images obtained from UAV. References | Related Articles | Metrics

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Rough set algorithm to predict RNA conserved secondary structure Fu, Hao-Yue (1); Zhang, Xiang-De (2); Xue, Ding-Yu (1) 2008, 29 (10):  1389-1392.  DOI: - Abstract ( 181 )   HTML   PDF (418KB) ( 766 )   A rough set algorithm was presented to predict the RNA conserved secondary structure. The date generating rules were made for the collated and discretized alternative RNA base pairs in the date mining modules for the predicting process of conserved structure by using the rough set software Rosetta as a tool. With these rules, the base pairs which will appear in the conserved secondary structure of the homologous RNA sequence were determined. The rough set algorithm was applied to the prediction of the conserved secondary structure of REV responsive element in the RNA of a set of HIV virus, and the results showed that in comparison with the conventional nondate mining algorithm, the prediction by rough set with such a machine learning algorithm used makes the predicted conserved structure more similar to the wild-type structure and the important structural branch more explicit. References | Related Articles | Metrics

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Stability analysis of networked control system with long-time delay and data packet dropout Xing, Wei (1); Wang, Jia-Fang (1); Wang, Guo-Liang (1) 2008, 29 (10):  1393-1397.  DOI: - Abstract ( 197 )   HTML   PDF (1490KB) ( 553 )   The stability of an NCS (networked control system) is studied, to which the stochastic transmission delay longer or shorter than a sampling period and the data packet dropout both come to pass simultaneously. The system is analyzed in detail so as to develop a model where the rate of data packet dropout is given and therefore the system modeled is regarded as an asynchronous dynamical system. Then, the sufficient condition for the exponential stability of the NCS is given on the basis of the theory of asynchronous dynamical system, with the dynamical feedback controller also given by solving a set of linear matrix inequalities. The numerical simulation results revealed the effectiveness of the proposed method. References | Related Articles | Metrics

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New method to estimate arc current for electric arc furnace Mao, Zhi-Zhong (1); Shang, Hai-Yang (1); Ma, Jian-Jun (3) 2008, 29 (10):  1398-1401.  DOI: - Abstract ( 234 )   HTML   PDF (1105KB) ( 530 )   To solve the problem that the arc current of electric arc furnace (EAF) is difficult to measure, a new method is proposed to estimate the EAF arc current by developing a relational data model between the arc current, three-phase power factors and primary three-phase load/no-load current of EAF transformer of which the operating principle is discussed. In view of that the load current is much higher than the no-load one during the actual transformer operation, the model is simplified to describe the relation between arc current, total active power and primary three-phase current and voltages of EAF transformer, where the no-load current of transformer is ignored. The validity of the method proposed is verified by both theory analysis and simulation results. References | Related Articles | Metrics

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Clustered routing protocol with distributed intrusion detection for wireless sensor networks Yao, Lan (1); Gao, Fu-Xiang (1); Yu, Ge (1) 2008, 29 (10):  1402-1405.  DOI: - Abstract ( 188 )   HTML   PDF (339KB) ( 655 )   Clustered routing protocols in wireless sensor networks (WSN) provide significant advantages for energy saving and data reprocessing. However, the reliability and security of the communications abiding by those protocols greatly depend on the cluster heads in which the severe security problems will possibly happen. So, a clustered routing protocol with distributed intrusion detection (DID) is proposed, i.e., all the nodes in WSN are involved in order for the preset of cipher keys to identify/detect the intrusive cluster heads in a distributed way. Experimental results demonstrated that compared with the classic cluster-based routing protocols in WSN, the energy consumption by the protocol with DID is quite less and presents a linear relationship with the tolerance of intrusive nodes. References | Related Articles | Metrics

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Fuzzy data modeling based on XML schema Yan, Li (1); Ma, Zong-Min (1); Liu, Jian (1); Yu, Ge (1) 2008, 29 (10):  1406-1409.  DOI: - Abstract ( 248 )   HTML   PDF (155KB) ( 730 )   To meet the requirement for imprecise and uncertain information processing in the actual applications of the Web, a fuzzy XML data model is developed on the basis of the XML Schema. With the model used, the fuzzy information in XML documents can be represented naturally. Based on the fuzzy set and possibility distribution theory, the multiple granularities of data fuzziness in XML documents are identified so as to provide various types of XML Schema representations that address all types of fuzziness. The fuzzy XML data model will lay a firm foundation for fuzzy data releasing and intelligent processing on the Web. References | Related Articles | Metrics

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Service discovery for composite process through matching of behavioral consistency Dai, Yu (1); Hao, Xian-Wen (1); Yang, Lei (1); Zhang, Bin (1) 2008, 29 (10):  1410-1413.  DOI: - Abstract ( 223 )   HTML   PDF (1202KB) ( 535 )   Service discovery for composite process is actually an exemplifying process through which the composite service is available. A new way is suggested to find the web service for the composite process through matching of behavioral consistency. Such approach establishes a behavioral-semantic matching relation between the service behavior and the role behavior needed to play. Thus, the problem of service discovery for composite process turns into that of semantic tree matching on the basis of path identification, and the solution is given to it correspondingly. Experimental results shows that the approach suggested can make sure of the completeness of the service discovered effectively and of the behavioral consistency of the service with composite service as well as the high-efficiency runtime. References | Related Articles | Metrics

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Relational algebraic theory of fuzzy temporal database Deng, Li-Guo (1); Ma, Zong-Min (1) 2008, 29 (10):  1414-1417+1430.  DOI: - Abstract ( 230 )   HTML   PDF (2296KB) ( 555 )   To bring further the abstract description provided by temporal database in accord with the actually objective world so as to express and deal with complex objects efficiently and support user-defined data types, with the modeling capability extended to reduce the cost due to the conversion of different types of data, a kind of 1NF (first normal form) relational algebra available to describe fuzzy temporal information is established by defining a series of fuzzy temporal elements via analyzing the basic temporal database model because the complex data are not only temporal but also fuzzy. The relevant mapping operation model of the fuzzy temporal relational algebra is theoretically demonstrated, thus avoiding the flow that the fuzzy temporal database is unable to provide the ambient facilities to express temporal information and enhancing the capability of existing temporal database to describe the characteristics of fuzzy matters. References | Related Articles | Metrics

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Effect of hierarchical topology on industrial ethernet Zhao, Hai (1); Bai, Zong-Zhen (1); Lin, Kai (1); Luo, Gui-Lan (1) 2008, 29 (10):  1418-1421.  DOI: - Abstract ( 253 )   HTML   PDF (305KB) ( 747 )   In order to analyze the rationality of hierarchical topology in Industrial Ethernet, the parameters of complicated fieldbus networks are abstracted so as to develop a network model at levels. The hierarchical topology network is compared with single bus network in respect to such performance indices as time delay, transmission speed, packet loss rate and how to deal with emergencies. The hierarchical topology network has not solved essentially the problem of uncertainty, but with the help of it, the performance of Industrial Ethernet has been optimized. The two topological networks in comparison are exactly evaluated, and in what case each of them is applicable is discussed separately. References | Related Articles | Metrics

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WSN data management based on non-standard 2D Haar wavelet transform Liao, Xian-Lin (1); Shi, Kai (1); Li, Xiao-Ming (1); Zhao, Lin-Liang (1) 2008, 29 (10):  1422-1425.  DOI: - Abstract ( 306 )   HTML   PDF (329KB) ( 594 )   The WSN management based on non-standard 2D Haar wavelet transform was designed to reduce the data transmission between nodes. Since the wavelet transform can be used to decompose the data into wavelet coefficients on different scales for transmission, the wavelet coefficients can be reconstructed to recover the original data. The algorithm of non-standard 2D Haar wavelet decomposition implements the aggregation of data, but the algorithm of non-standard 2D Haar wavelet inverse transform implements the reconstruction of date. The result of the MATLAB simulation showed that the wavelet transform data management structure can decrease greatly the load of data transmission with the features of those data kept up. References | Related Articles | Metrics

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Effect of Al2O3 on microstructure and mechanical properties of B4C-Al2O3-Al composites Lu, Peng (1); Ru, Hong-Qiang (1); Yu, Liang (1); Sun, Xu-Dong (1) 2008, 29 (10):  1426-1430.  DOI: - Abstract ( 265 )   HTML   PDF (588KB) ( 1390 )   B4C-Al2O3-Al composites were prepared by aluminizing the B4C-Al2O3 preforms in vacuum, and the effect of Al2O3 on the microstructure and mechanical properties of the composites was analyzed. The results showed that B4C-Al2O3-Al composite is mainly composed of B4C, Al2O3, Al, Al3BC and AlB2. With the increasing w(Al2O3), the hardness increases first then decreases, but the bending strength and fracture toughness decrease first then increase. The porosity, hardness, bending strength and fracture toughness of the composite when w(Al2O3)=25% are 2.06%, 84.4 HRA, 440.36 MPa and 6.53 MPa·m1/2, respectively. The toughening improvement of the composites mainly results from the addition of ductile aluminum, crack deflection/bifurcation, grain refinement, formation of toughening phase AlB2 and mismatching of thermal expansion between the matrix B4C and the Al2O3 particles. It was found that the fracture is mainly in intergranular and transgranular forms, and on the fracture surface there are torn edges due to aluminizing. References | Related Articles | Metrics

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Study on dynamic recrystallization behavior of Nb-microalloyed steel Dong, Yi (1); Xu, Yun-Bo (1); Xiao, Bao-Liang (1); Wu, Di (1) 2008, 29 (10):  1431-1434.  DOI: - Abstract ( 217 )   HTML   PDF (659KB) ( 801 )   The dynamic recrystallization behavior of the specimens of Nb-microalloyed steel was tested on Gleeble-2000 thermomechanical simulator by way of single pass at high temperature. The results revealed some facts about the specimen as follows. The dynamic recrystallization of which the activation energy 304.711 kJ/mol is liable to occur at higher temperature and lower strain rate, and the stress-strain curve in form of dynamic recovery changes into dynamic recrystallization with decreasing lnZ. The curves present several peaks, which means that it's in intermittent form of dynamic recrystallization when lnZ < 22.61. It's found that the peak stress/strain and critical strain all bear linear relationship with lnZ. The starting time of dynamic recrystallization decreases with increasing strain rate and temperature. References | Related Articles | Metrics

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Investigation on cold rolling for titanium sheet under tensional effect Wu, Di (1); Wang, Gui-Qiao (1); Wang, Jing-Dong (1); Wang, Guo-Dong (1) 2008, 29 (10):  1435-1437+1442.  DOI: - Abstract ( 251 )   HTML   PDF (230KB) ( 806 )   The inefficiency problem during cold rolling of titanium sheet without tension exerted on it was investigated. The state equation of stress of titanium sheet under tensional effect is deduced on the basis of Hill's anisotropic yield criterion in combination with the anisotropic characteristics of titanium's mechanical properties. It was found theoretically that the feasibility of cold rolling of titanium sheet under tensional effect mainly depends on titanium's plastic deformation conditions and the state of stress. An experimental investigation was therefore carried out on a 4-high reversible cold-rolling mill in lab for titanium sheet under tensional effect, and the result showed that heavy-reduction cold rolling process for titanium sheet just by single pass is available if the tension is chosen appropriately, from which the shape of sheet thus obtained is favorable with rolling efficiency improved remarkably. References | Related Articles | Metrics

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Application of modified GA-ANN network to rolling force prediction Fu, Tian-Liang (1); Wang, Zhao-Dong (1); Wang, Guo-Dong (1); Wu, Shang-Chao (2) 2008, 29 (10):  1438-1442.  DOI: - Abstract ( 270 )   HTML   PDF (1144KB) ( 493 )   In the process of real production, the calculation results by conventional models have relatively big errors in the prediction of rolling force. It is therefore suggested to combine the BP network with modified GA algorithm to develop a prediction model, i.e., predicting the rolling force to be applied to medium thick plates by means of the guidable idea about search from BP network and the capability of global search from genetic algorithm. Moreover, the corresponding program and interface were given according to the prediction model. Based on the in-situ data taken from Handan and Puyang plate rolling mills, some optimal data was selected to predict the off-line rolling force. The results showed that the predicted accuracy resulting from the model developed is higher than that from conventional models, i.e., the relative error is within 4%, thus meeting the actual requirement for plate rolling. References | Related Articles | Metrics

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Discussion on design of CVC roll profile and its equivalent crown Liu, Guang-Ming (0); Di, Hong-Shuang (0); Chang, An (0); Hou, Ze-Yue (0) 2008, 29 (10):  1443-1446.  DOI: - Abstract ( 308 )   HTML   PDF (219KB) ( 1233 )   The ways to determine the equivalent crown of the CVC roll were found imperfect in earlier works, which caused the inaccurate curve in designing CVC rolls. The method of improvement is therefore proposed with the solution given to the cubic curve of CVC rolls. The equivalent crown of CVC roll is analyzed then regarded as the function of roll shift and strip width, and the equation of the equivalent crown involving strip width is derived, which provides theoretically the reference for the crown control of different strip widths. The calculation result showed that the method proposed is correct, and it is proved that for the mill on which the CVC roll profile is cubic curve, the wider the strip, the wider the crown control range and the more remarkable the effect of CVC shift on the strip crown. References | Related Articles | Metrics

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On the pyrolytic properties of Fushun oil shale and its residue Xue, Xiang-Xin (1); Li, Yong (1); Feng, Zong-Yu (1) 2008, 29 (10):  1447-1449+1454.  DOI: - Abstract ( 210 )   HTML   PDF (1095KB) ( 564 )   A thermogravimetric analysis was made to investigate the pyrolytic properties of the Fushun oil shale and its residue. The results showed that their pyrolytic reaction can be divided into two processes. The first one is mainly the moisture volatilization within the range from room temperature to 200°C, then the moisture volatilization contents in the oil shale and its residue are 2.446% and 3.202%, respectively. The second one is mainly the pyrolysis of fixed carbon between 200°C and 600°C, then the rates of weight loss of oil shale and its residue are 16.048% and 6.524%, respectively. And the Coats-Redfern method is used to get the kinetic constant in pyrolytic reaction. Correspondingly, the activation energies of the kerogen shale are 51.84 and 28.14 kJ/mol, and the frequency factors are 62.35 and 0.00325 min-1, respectively. The activation energies of oil shale residue are 36.62 and 55.05 kJ/mol, and the frequency factors are 0.00976 and 0.341 min-1, respectively. In addition, there are 6.524% of organic matters in the residue which can be utilized further. References | Related Articles | Metrics

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Preparation of glass-ceramics from oil shale residue Li, Yong (1); Feng, Zong-Yu (1); Yang, He (1); Xue, Xiang-Xin (1) 2008, 29 (10):  1450-1454.  DOI: - Abstract ( 269 )   HTML   PDF (1127KB) ( 608 )   A glass-ceramics was prepared with oil shale residue as primary material. The compositions of glass-ceramics and selection of both main crystallization and nucleating agents were discussed. The effects of nucleating agents and heat treatment procedure on glass-ceramics were analyzed by means of DTA, XRD and SEM. The results showed that the composite nucleating agent TiO2+P2O5 can efficiently step up the crystallization of such a glass-ceramics. The optimal heat treatment procedure was found as nucleating at 850°C for 100 min and the crystallizing at 980°C for 80 min. The major and minor crystallization phases of the glass-ceramics is hedenbergite and anorthite, respectively. There are several peaks found in the infrared absorption band, and the crystals present fibrous structures in staggered distribution. The service performance of the glass-ceramics thus prepared is evidently better than that of other building and decorative materials, such as ceramic tile, marble and granite. References | Related Articles | Metrics

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Experimental investigation on vacuum-thermal reduction of ascharite with silicon-aluminum alloy as reductant Xu, Dong (1); Zhang, Xian-Peng (1); Li, Jie (1); Cheng, En-Qing (2) 2008, 29 (10):  1455-1458.  DOI: - Abstract ( 429 )   HTML   PDF (223KB) ( 638 )   In order to utilize effectively the ascharite mineral which contain low grade B2O3, the vacuum-thermal reduction of roasted ascharite to deoxygenize magnesia into magnesium with silicon-aluminum alloy as reductant was experimentally investigated. The orthogonal test results showed that the best conditions for the reduction process are at 1453 K for 2 h, with briquetting pressure 35 MPa and excess coefficient reductant of 10% and, as a result, the ratio of reduction is up to 63.7%. In addition, the residue of the reduction process could be used as raw materials to make non-alkali glass ball. The reduction process is environment friendly, thus finding out a new way to utilize comprehensively ascharite mineral. References | Related Articles | Metrics

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On the annealing process for cold rolled Mg-9Li-1Zn alloy plate Zu, Guo-Yin (1); Song, Bin-Na (1); Li, Ting-Gang (1); Yao, Guang-Chun (1) 2008, 29 (10):  1459-1462+1466.  DOI: - Abstract ( 228 )   HTML   PDF (1558KB) ( 489 )   In order to improve the deformability of cold rolled Mg-Li alloy plate, the annealing process for cold rolled Mg-9Li-1Zn alloy plate was investigated systematically to discuss the effects of annealing temperature/time on the microstructure and mechanical properties of the plate. The results showed that the appropriate annealing temperature is 280-300°C, and the further grain growing and surface lithium losing will occur if the temperature is too high. The hardness of alloy is 426.7 MPa after annealing at 300°C for 60 min, and the total cold deformation rate can be up to 70% after fully recrystallizing/softening. The criterion for annealing time of Mg-9Li-1Zn alloy is to make sure of the spheroidization of α phase and homogenization of microstructure. For this reason, the optimum annealing process should be at 300°C for 60 min as the result of tests. References | Related Articles | Metrics

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Divergence/flutter of the beam with intermediate support Jing, Hong-Ying (1); Jin, Ji-Duo (2); Wen, Bang-Chun (1) 2008, 29 (10):  1463-1466.  DOI: - Abstract ( 366 )   HTML   PDF (2024KB) ( 643 )   The vibration of a beam which is simply supported at one end, resting on a support at some intermediate location, and has the other end subjected to an axial force is studied. The characteristic equation of the beam is derived, as well as an analytic expression of its eigenfunction. Then based on the characteristic equation, the effect of the position of intermediate support on the natural frequencies of the beam is discussed. The differential equation of the beam's motion is discretized applying the first three eigenfunctions by Ritz-Galerkin method, thus getting the critical axial force for the beam destabilization when the intermediate support is positioned differently. It is found that there is a special position of intermediate support ξl, as the axial load P increases, for location of intermediate support ξb < ξl, the beam becomes unstable by flutter, and for ξb > ξl, it loses stability by divergence. References | Related Articles | Metrics

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Contrastive analysis of convex arithmetic and interval arithmetic in reliability design Wang, Xin-Gang (1); Zhang, Yi-Min (1); Wang, Bao-Yan (2); Wen, Bang-Chun (1) 2008, 29 (10):  1467-1469.  DOI: - Abstract ( 231 )   HTML   PDF (232KB) ( 568 )   A contrastive analysis of non-probabilistic reliability index was made theoretically and graphically between the relevant interval model and convex set model. It was found that there is a unidirectional consistence between the non-probabilistic reliability indices determined by two different arithmetics, i.e., the interval arithmetic and convex arithmetic. It means that if an index is thought to be reliable by the interval arithmetic, the index is necessarily thought to be reliable by the convex arithmetic as well but not vice versa. However, the interval arithmetic is relatively conservation than the convex one in judging the reliability on index basis, and a conclusion is therefore drawn that the convex arithmetic is more practical in production/engineering. The conclusion is further proved through the comparison of non-probabilistic reliability index obtained by the two arithmetics. References | Related Articles | Metrics

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Optimum design of mechanism biped robot with heterogeneous legs Xie, Hua-Long (1); Xu, Zhi-Wei (1); Shi, Jia-Shun (1); Xu, Xin-He (2) 2008, 29 (10):  1470-1473.  DOI: - Abstract ( 293 )   HTML   PDF (271KB) ( 670 )   To provide an ideal platform for the R&D of intelligent bionic legs, a new pattern of humanoid robot, i.e., the biped robot with heterogeneous legs (BRHL), is proposed. The concept of BRHL and the reason for investigating it are given with its bionic design described. Taking a bionic leg as example, the kinematic model of BRHL is developed since various mechanical structures of both legs are similar. Then, the principle of optimization, objective function and constraint conditions of BRHL design are discussed. The optimum design was done according to the processed data of normal person's gait, and the result indicated that BRHL can implement well the anthropomorphic gait and is an ideal platform for R&D of intelligent bionic legs. References | Related Articles | Metrics

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FEA on the spindle assembly of high speed machine tool Zhang, Yao-Man (1); Liu, Chun-Shi (2); Xie, Zhi-Kun (2); Liu, Yong-Xian (1) 2008, 29 (10):  1474-1477.  DOI: - Abstract ( 334 )   HTML   PDF (481KB) ( 1268 )   The finite element dynamic analysis model of the spindle assembly was developed by taking the advantage of the spring-damper elements to simulate the bearing supports. The FEA model were developed first by introducing 2 or 3 groups of circumferential spring-damper elements which were arranged at different angle around the spindle, then the effect of different supporting conditions and different arrange angles on the modal analysis of the spindle assembly were comparatively discussed to select the most rational FEA modal. The modal analysis and harmonic analysis were both made to confirm the dynamic characteristics of spindle assembly of CHH6125 high-speed NC machine tool developed and manufactured by Shenyang No.1 Plant of Machine Tools, and the results were compared with the testing ones. The correctness of the FEA model is available to the dynamic performance of the spindle assembly. References | Related Articles | Metrics

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Modeling and experimental study on micro-milling polycrystalline material Wang, Jin-Sheng (1); Shi, Jia-Shun (1); Gong, Ya-Dong (1); Abba, Gabriel (2) 2008, 29 (10):  1478-1481.  DOI: - Abstract ( 274 )   HTML   PDF (1214KB) ( 555 )   Through the detailed analysis of the machining mechanism of micro-milling polycrystalline materials, a micro-milling model is developed, where the effects of minimum chip thickness and metal phase on the mechanism are focused on. Also, how they affect the micro-milling force and surface generation are discussed in detail. It is found that the difference between grains results in the surface fluctuation and additional vibration to the cutting force. Whether the grain is cut or not by the tool depends on its minimum chip thickness, which also causes the high frequency vibration during machining. Through many experimental studies, the results revealed that the model we developed is able to predict the micro-milling process, which provides theoretical supports to optimize micro-milling parameters so as to improve the efficiency and quality of products. References | Related Articles | Metrics

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40Ar-39Ar isotopic dating for Paishanlou gold deposit and its geological implication Wang, Rong-Hu (1); Jin, Cheng-Zhu (1); Li, Jing-Chun (2) 2008, 29 (10):  1482-1485.  DOI: - Abstract ( 244 )   HTML   PDF (1002KB) ( 788 )   The Paishanlou big gold deposit is situated in the margin of the North China Craton, and the gold deposit is in the Archeozoic meta-volcanic rock of Wulashan group. The ore body especially the host is strictly controlled by ductile shear zone and in the biotite-anorthose and gneissic/felsic mylonite. The 40Ar-39Ar isotopic geochronology of the potassium feldspar formed in the metallization phase in the gold deposit was studied. The result showed that the K-feldspar has an 40Ar-39Ar plateau age (116.69 ± 1.15) Ma and isochron age (116.97 ± 1.39) Ma, which reveal the age of the deposit, i.e., formed in early Cretaceous. And the K-feldspar in the prorphyro-like granite has an 40Ar-39Ar plateau age (126.71 ± 2.03) Ma and isochron age (124.00 ± 4.32) Ma, which reveal that the mineralization was beginning not earlier than (126.71 ± 2.03) Ma ago. The age of Paishanlou gold deposit is in close coincidence with other gold deposits situated in the margin of the North China Craton. The result indicated that most of the gold deposits in the same region formed in the period during which the geodynamic metamorphism occurred in East China during Mesozoic era. References | Related Articles | Metrics

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Analysis of material input in Shenyang city Zheng, You-Yi (1); Wang, Qing (1); Hu, Bo (1); Gu, Xiao-Wei (1) 2008, 29 (10):  1486-1489+1493.  DOI: - Abstract ( 202 )   HTML   PDF (546KB) ( 419 )   Based on the annual data of production and consumption recorded for Shenyang City, a material flow account from 1990 to 2004 was rendered for Shenyang's economical system. The results showed that in the 15 years the direct material input was increased by 149.9% with an average annual growth rate 6.8%. On the other hand, according to the constant price of 1978, the GDP of the city in 2004 was near four times higher than in 1990, with an average annual growth rate up to 11.7%. Accordingly, the resource efficiency was increased by 87.3%, or an average annual growth rate 4.6%. The improvement of resource efficiency reveals that in the city the material consumption in economic development had been decreased to a certain extent. However, the comparative growth rate of resource efficiency was much lower than that of GDP. The fact means that the rapid economic development shall impact greater on the city's ecological/environmental system if the current economic development pattern keeps on. References | Related Articles | Metrics

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Hydration of hemihydrated calcium sulfate whiskers Han, Yue-Xin (1); Wang, Yu-Bin (1); Yuan, Zhi-Tao (1); Yin, Wan-Zhong (1) 2008, 29 (10):  1490-1493.  DOI: - Abstract ( 253 )   HTML   PDF (463KB) ( 1025 )   Both real-time and out-of-time observations and XRD analysis were carried out for the products from the hydration process of hemihydrated calcium sulfate whiskers. The results indicated that the process is characterized mainly by the changes of crystalline form and morphology of whiskers and the reduction of whiskers' aspect ratio. Based on the observations it was found that the hydration process of hemihydrated calcium sulfate whiskers can be divided into three phases, i.e., the initial hydration of hemihydrated calcium sulfate whiskers, the formation of dihydrated calcium sulfate whiskers and the dihydrated calcium sulfate whiskers thickening/dissolving with formation of new dihydrated calcium sulfate in crystalline form. In addition, the hemihydrated calcium sulfate whiskers are slightly different from hemihydrated gypsum in hydration process. References | Related Articles | Metrics

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Toughening of calcium sulfate whisker-PP composite by surface treatment agents Wang, Xiao-Li (1); Zhu, Yi-Min (1); Han, Yue-Xin (1); Yuan, Zhi-Tao (1) 2008, 29 (10):  1494-1497.  DOI: - Abstract ( 278 )   HTML   PDF (293KB) ( 858 )   Calcium sulfate whiskers were modified by two kinds of surface treatment agents and added into polypropylene to prepare the calcium sulfate whisker-PP composite, of which the mechanical properties were tested. The results showed that the notched impact strength of the composite on izod tester increases dramatically after adding calcium sulfate whiskers. When 10% of the calcium sulfate whiskers in the composite was modified by the titanates NDZ-401, the notched impact strength of the composite is increased by over 85%. SEM was utilized to observe the morphology of impact fracture surface of the composite and dispersion of calcium sulfate whiskers in PP matrix. The results indicated that surface treatment can step up the uniform dispersion of calcium sulfate whiskers in PP matrix, and the notched impact strength to improve greatly the toughness of the composite. In this respect the surface treatment agents play a positive role. References | Related Articles | Metrics

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Calculation of axial compressive force of prestressed FRP bar-concrete composite beam under uniformly distributed load Wang, De-Xuan (1); Wang, Lian-Guang (1); Zhang, Bin (2) 2008, 29 (10):  1498-1501.  DOI: - Abstract ( 264 )   HTML   PDF (381KB) ( 742 )   The relative slip will unavoidably come to pass on the bar-concrete interface in a prestressed FRP bar-concrete composite beam under external loading, and the stress in a prestressed FRP bar increases correspondingly with the external loading. The interface slip and stress increment will result in the stress redistribution between concrete flange plate, and H-steel beam and shear connector. According to the structural and bearing characteristics and elastic theory, some differential equations of axial force on which the effects of both interface slip and stress increment are taken into account are given, as well as the formulae of the axial force acting on both the concrete slab and H-steel beam under uniformly distributed load. The results of calculation showed that the axial force to the composite beam increases with the increasing connection stiffness and external load, and the maximum axial force is found at the midspan, then it decreases gradually from midspan to beam end where it is approximately zero. As to the effect of stress increment in prestressed FRP bars on the axial force to composite beam, it is so small that it can be ignored. References | Related Articles | Metrics

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Analysis of axially-loaded short columns of square steel tube filled with steel-reinforced high-strength concrete Zhao, Tong-Feng (1); Wang, Lian-Guang (1); Zhao, Shuang (2) 2008, 29 (10):  1502-1504.  DOI: - Abstract ( 199 )   HTML   PDF (905KB) ( 500 )   To study further the properties of an axially-loaded short column of square steel tube filled with steel-reinforced high-strength concrete, an improved stress-strain model was developed for confined core concrete considering comprehensively the effect of steel-reinforcements on concrete. Fiber modeling was introduced in programming a nonlinear analysis to compute the relationship between loading and longitudinal strain, and the result is compared with the experimental ones in earlier works. The computed results were proved in good agreement with the experimental ones. Based on the regression analysis of a great deal of computed results, the formula to calculate the axially-loaded short column of square steel tube filled with steel-reinforced concrete is given. References | Related Articles | Metrics

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3D-numerical simulation on failure process of concrete-filled steel tube column Ling, Li (1); Tang, Chun-An (2); Wang, Shu-Hong (1); Liang, Zheng-Zhao (2) 2008, 29 (10):  1505-1508.  DOI: - Abstract ( 257 )   HTML   PDF (308KB) ( 591 )   The RFPA3D (realistic failure process analysis) code is used to simulate the concrete-filled short rectangular steel tube columns. The whole process including loading, deformation, failure and crack initiation/propagation of the short column is numerically simulated. A certain statistical function is introduced into the numerical model to reflect the concrete heterogeneity. The elastic modulus and other mechanical properties are all weakened when the stress in elements satisfies the failure criterion. The progressive failure process of the column is brought to pass by way of increasing load to induce further displacement. The relationship between the ultimate load-carrying capacity and length of the steel tube are given with the change of cross-section area of concrete taken into account. The whole failure process of those samples is thus reproduced through RFPA3D numerical evaluation. The results indicated that RFPA3D can provide a new way to study the concrete-filled steel tube. References | Related Articles | Metrics

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Interval number density middle operator in uncertain multiple attribute decision making Hou, Fang (1); Guo, Ya-Jun (1) 2008, 29 (10):  1509-1512+1516.  DOI: - Abstract ( 209 )   HTML   PDF (2187KB) ( 620 )   Considering the information distribution on the decision makers' preference, the problem of density weighted averaging middle operator in uncertain multiple attribute decision making is investigated to find out the procedure to determine the weight vector of interval number density operator by extending the middle operator of density of real numbers to that of interval numbers. An interval number density middle (IDM) operator is thus proposed with the interval number density weighted average (IDWA) operator and the interval number density weighted geometric average (IDWGA) operator both defined to give the synthesized operators based on IDM operator, i.e., the arithmetically weighted IDWA or IDWAWAA operator and the orderly weighted IDWGA or IDWGAOWA operator. A numerical example is given to illustrate how to determine the density weight vector of operators. References | Related Articles | Metrics

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Examination mechanism design to select alliance members of a virtual enterprise Lu, Ji-Hua (1); Li, Yan (1); Zhao, Xi-Nan (1) 2008, 29 (10):  1513-1516.  DOI: - Abstract ( 185 )   HTML   PDF (150KB) ( 639 )   The selection of alliance members of a virtual enterprise is studied on project basis. Based on the principal-agent theory and the assumptions that the fixed cost, costing and retention utility have all come true in the alliance, an optimal examination mechanism is proposed via adverse selection. It reveals that the leader of the alliance has to design an examination mechanism according to enable every alliance member to participate actively in the alliance and work harder for it so as to implement the high-efficiency resource allocation, according to the correlativity of individual information actually offered by the alliance members who worked highly or lowly efficiently. The study is done with the intention of solving the project-based profit sharing problem in a virtual enterprise in accordance to how a member worked and what and how much information a member offered. Thus, it provides a theoretical base to a certain degree to solve the problem of alliance member selection in such virtual enterprises. The calculation results indicated that the optimal contract examination via adverse selection by the leader in accordance to the different information structures is in conformity with actual conditions. References | Related Articles | Metrics

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Dynamic topology based study on formation mechanism of assignments for research centers of chinese universities Sheng, Qi-Zhi (1); Zhao, Xi-Nan (1) 2008, 29 (10):  1517-1520.  DOI: - Abstract ( 182 )   HTML   PDF (935KB) ( 461 )   Research centers especially the cross-disciplinary scholarly research centers are a special academic zone in either research university or research-teaching university, which has been recommended in Chinese "985 project" as innovational platforms. The topologic space theory in mathematics is applied to the study on the formation mechanism of assignments for the research centers of Chinese universities, thus providing a topological dynamic for the requirement of new assignments. A storehouse of research assignments based on dynamic topology is built according to the rules that the cross-disciplinary information is possible to result in new sci-tech achievements. In the topological storehouse a relation between different elements is established to make functional analysis of the elements in topological space. Absorbing the foreign experience in starting research centers of advanced universities, the formation process of the assignments for those research centers is envisaged, which may be beneficial to Chinese research or research-teaching universities. References | Related Articles | Metrics