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15 November 2008, Volume 29 Issue 11 Previous Issue    Next Issue
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Effect of heterogeneous distribution of degree on synchronization in complex networks Hao, Bin-Bin (1); Jing, Yuan-Wei (1); Zhang, Si-Ying (1) 2008, 29 (11):  1521-1524.  DOI: - Abstract ( 827 )   HTML   PDF (393KB) ( 1183 )   Discusses a class of continuously variable network models which are heterogeneously distributed in between scale-free networks and random networks. With an idea proposed, i.e., link density and under the precondition that the size of networks remains unchanged, the effects of the heterogeneous distribution of degree and link density on the synchronizability of network are investigated and, based on the synchronization criterion, the synchroniabilities of two types of networks are explored. As a result it is found that for Type I networks the correlation between networks synchronizability and heterogeneous distribution of degree is affected by the link density, and the former two are independent of the latter if it is quite small. As to the Type II, the synchronizability is affected jointly by the networks' heterogeneous distribution of degree, size and link density. And the higher the heterogeneity, the larger the networks' size and the lower the link density are, the more difficult the synchronization of Type II networks will be. References | Related Articles | Metrics

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Reliable design of fuzzy controller for a class of nonlinear systems Zhai, Ding (1); Yuan, Ping (2); Liu, Guo-Yi (1); Liang, Li (3) 2008, 29 (11):  1525-1527.  DOI: - Abstract ( 219 )   HTML   PDF (1033KB) ( 455 )   Based on the T-S fuzzy model and proceeding with the reliability of normally closed-loop systems, the reliable design of fuzzy controller for a class of nonlinear systems is discussed via linear matrix inequality (LMI). Describing and comparing the earlier works, the sufficient condition for the mathematical model of T-S fuzzy system is given in terms of LMI, with the design method of reliable controller proposed. The controller thus designed enables the fault closed-loop systems to be restabilized of with quadratic stability so as to satisfy the performance indices in applications. A numerical example is given to verify the effectiveness of the design procedure. References | Related Articles | Metrics

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Detection algorithm based on hybrid classification for pulmonary nodules Guo, Wei (1); Wei, Ying (1); Zhou, Han-Xun (1); Xue, Ding-Yu (1) 2008, 29 (11):  1528-1531.  DOI: - Abstract ( 217 )   HTML   PDF (225KB) ( 563 )   The approach to weight segmentation with optimum threshold values was used to get the pulmonary parenchyma, and the regions of interests (ROI) were obtained by C-means clustering algorithm and classified by hybrid method, during which two three-dimensional characteristics of pulmonary nodules and two corresponding rules were defined for regular initial classification. Then, a nonlinear classifier was constructed by improving the Mahalanobis distance vector to classify ROI again, so as to lower the false positive. After the hybrid classification, the pulmonary nodules were differentiated efficiently from such interfering information as bloods. Experiment results indicated that the algorithm is highly sensitive to detecting pulmonary nodules. References | Related Articles | Metrics

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Compensating strategy based on dynamic matrix control for networked control system Guan, Shou-Ping (1); Ying, Ting (1) 2008, 29 (11):  1532-1535.  DOI: - Abstract ( 270 )   HTML   PDF (1058KB) ( 518 )   Considering the data packets uncertainty in networked control system (NCS), its influence on NCS and relevant existing controlling methods are analyzed. Then a distributed NCS model is developed where the controller is event-time with senor and actuator both time driven. Based on the simple and practical dynamic matrix method for predictive control, a new compensating strategy is proposed for network time delay and packet dropout and simulated. The results show that the output from the NCS after compensation strategy is much the same as the output from the system where the network time delay remains unchanged but the data packets arrive on time. The effectiveness of the compensating strategy is thus verified. References | Related Articles | Metrics

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Application of BP neural network to GPS differentiation positioning Liu, Ying-Ying (1); Xu, Xiang-Kun (2); Wei, Jing-Min (2); Jin, Ya-Ling (2) 2008, 29 (11):  1536-1539.  DOI: - Abstract ( 329 )   HTML   PDF (793KB) ( 1067 )   In view of that GPS (global position systems) mobile terminals are poor in signal demasking and that the position resulting from direct computation by the mathematical model of GPS differentiation is difficult to keep the exact information continuously, the BP neural network is applied to position forecast, to improve the real-time accuracy of positioning information. With the neural network trained by the data introduced in and its model simulated, the results show that the positioning accuracy is quite high. It proves that this method is worth using. References | Related Articles | Metrics

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Pixon-based normalized cuts and image segmentation Cui, Hua (1); Gao, Li-Qun (1) 2008, 29 (11):  1540-1543.  DOI: - Abstract ( 313 )   HTML   PDF (398KB) ( 513 )   Normalized cut, as an image segmentation technique, requires a great deal of operation since an eigenvector is needed to solve the large-scale matrix in operation process. To get rid of such a trouble, a new approach is proposed combining the normalized cut with a Pixon-based image model, i.e., the model should be obtained first, then the normalized cut technique is applied to the model so as to segment images recursively. Experimental results showed that the approach proposed can reduce greatly the operational quantity and memory consumption as using the normalized cut singly in image segmentation, thus improving the efficiency and practicability. References | Related Articles | Metrics

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New fuzzy pricing approach to real option Zhu, Dan-Mei (1); Zhang, Tie (1); Chen, Dong-Ling (1); Gao, Hong-Xia (2) 2008, 29 (11):  1544-1547.  DOI: - Abstract ( 305 )   HTML   PDF (235KB) ( 564 )   In real option pricing, it is impractical to assume the present value of expected cash flow payoff as an exact number because it is a forecast one. Generally, the number is regarded as a triangular or trapezoidal fuzzy number to give its estimated interval values and the Black-Scholes (abbreviated as B-S) formula is used to price the real option. A new pricing approach to real option is thus proposed to transform the forecast intervals evaluated by experts into some normal fuzzy numbers with the lattice closeness degree introduced to construct weighted vectors. In this way the rationality of estimating the present value of expected cash flow payoff by using a normal fuzzy number is verified. A numerical example is given to illustrate the validity of the approach proposed. References | Related Articles | Metrics

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On the production order planning of integrated steel production SM-CC-HR-FF Yu, Chun-Yue (1); Xu, Mei-Rong (1); Qu, Rong-Xia (1) 2008, 29 (11):  1548-1551.  DOI: - Abstract ( 284 )   HTML   PDF (963KB) ( 583 )   A production order planning optimization model is developed for the integrated steelmaking-continuous casting-hot rolling-final finish (SM-CC-HR-FF) process in a steel plant, where the steelmaking and hot rolling are regarded as the key steps. The objectives are to maximize the hot charging proportion of slabs and minimize the early/delayed delivery time and the slabs which are surplus to the requirements for hot/rolling. The main constraints including steelmaking and hot rolling capacities, steel grade and slab and product dimensions are all taken into consideration in the model. A two-level chromosomes genetic algorithm is designed to solve the model. At the order planning level, the problem how to match the steel grade and dimensions during continuous casting with those during hot rolling in the integrated process of steel production is solved. Then, the order plan thus obtained becomes the reasonable production order pool by which both the batch planning and static scheduling of integrated steel production are available. A simulation example shows the reasonability of the model and validity of the algorithm. References | Related Articles | Metrics

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Complex semantically supported modeling/optimization of joining execution of sliding window queries over data streams Gu, Yu (1); Li, Xiao-Jing (1); Xu, Jia (1); Yu, Ge (1) 2008, 29 (11):  1552-1555.  DOI: - Abstract ( 245 )   HTML   PDF (306KB) ( 624 )   How the data stream is executed continuously will affect the efficiency of the query and correctness of its result. Based on the relevant streaming methods of the STREAM project, the semantic exactness during the joining execution of sliding window queries over data streams is analyzed and modeled under complex conditions, and two improved basic maintenance strategies are proposed taking time-based window as example. Furthermore, the maintenance schema for tuple-based and partition-based windows is illustrated and the adaptive maintenance in accordance to different parameters and environments is discussed. Experimental results showed that under conditions of different window, stream rates and selectivities the optimization algorithm to which the adaptivities are differently chosen will have the ideal processing performance. References | Related Articles | Metrics

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Vague ALC(D): A fuzzy description logic based on vague sets Wang, Xing (1); Ma, Zong-Min (1); Lu, Yan-Hui (1); Wang, Hai-Long (1) 2008, 29 (11):  1556-1559+1580.  DOI: - Abstract ( 297 )   HTML   PDF (2176KB) ( 857 )   The ordinary fuzzy description logic with a single membership degree is unable to represent imprecise knowledge but describes knowledge at an abstract level, thus lacking powerful means to express the numerical information on physical substances. A fuzzy description logic based on vague sets and combined with concrete domain, named vague ALC(D), is therefore proposed, where the vague sets are employed to represent fuzzy knowledge by membership degree intervals. The syntax, semantics and inference rules of vague ALC(D) are given, as well as the relevant tableaux algorithm that is developed for reasoning in the vague ALC(D). The vague ALC(D) enables the representation and inference of fuzzy knowledge including numerical information to be more accurate, thus enhancing its expressability and reasonability in fuzzy description logic. References | Related Articles | Metrics

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Implementation of dynamic-priority scheduling algorithm and EDF algorithm in WebitOS Zhao, Hai (1); Zhou, Feng (1); Luo, Ding-Ding (1) 2008, 29 (11):  1560-1563.  DOI: - Abstract ( 259 )   HTML   PDF (319KB) ( 645 )   Compared with the static-priority scheduling algorithms in real-time system, the dynamic-priority scheduling algorithms, which can set different deadlines for different jobs of each and every task to reflect the time constraint on tasks better. A dynamic-priority scheduling algorithm designed and implemented in the WebitOS real-time operating system on the basis of the high availability scheduling of earliest deadline first (EDF) algorithm with an early discarding rule specified for next job. Test results showed that the rule enhances the scheduling performance of the EDF algorithm as a whole under over-loaded condition. References | Related Articles | Metrics

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Energy-balanced reliable routing metric for wireless sensor networks Zhang, Xi-Yuan (1); Zhao, Hai (1); Xu, Jiu-Qiang (1); Zhu, Jian (1) 2008, 29 (11):  1564-1567.  DOI: - Abstract ( 390 )   HTML   PDF (284KB) ( 636 )   Ensuring the end-to-end data transfer reliability, decreasing energy cost of batteries and prolonging the network lifetime have been the important factors for routing protocol design in wireless sensor networks. After developing an optimization model of lifetime, the disadvantage of ETX metric is analyzed and overcome by introducing an energy-balanced reliable routing metric-EBRM which is based on the strategy of energy hierarchy. Simulation test on NS-2 shows that the EBRM, which can prolong network lifetime effectively and ensure reliable end-to-end transfer, is more suitable for the application of wireless sensor networks. References | Related Articles | Metrics

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Crack propagation rate of 400 MPa super-steel strip Gao, Cai-Ru (1); Liu, Xiang-Hua (1); Du, Lin-Xiu (1); Jia, Kun-Ning (1) 2008, 29 (11):  1568-1571.  DOI: - Abstract ( 278 )   HTML   PDF (1324KB) ( 601 )   On the high-frequency fatigue tester PLG-100, the crack propagation rate of 400 MPa super-steel strip was tested at 80 Hz by three-point bending method. The relationship between the propagation rate da/dN and the amplitude of stress intensity factor was given. Then, with the software Origin 7.0 in combination with linear fitting, the coefficient C and m in Paris equation were determined as C=9.4 × 10-12 mm each time and 4.47respectively, and the threshold value of crack propagation ΔKth was 7.98 MPa·m1/2 through calculation. References | Related Articles | Metrics

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Influence of UFC final cooling temperature on structure and microhardness of bearing steel rod Sun, Yan-Kun (1); Wu, Di (1) 2008, 29 (11):  1572-1575.  DOI: - Abstract ( 338 )   HTML   PDF (664KB) ( 1102 )   GCr15 bearing steel rod was investigated to analyze the influence of UFC (ultra fast cooling) final cooling temperature on its structure and microhardness. It was found that along with UFC temperature drop the diameter of spheroidal pearlites and interval of lamellar pearlites both decrease if the UFC rate is higher than 100°C/sec after high-temperature final rolling to cool the workpiece to a certain degree then it is slowly cooled to ambient temperature. The higher temperature of final cooling can thin down the intercrystalline carbides but cannot suppress the precipitation of network carbides. However, the thinly lamellar pearlite structure is available by the precipitation of suppressed network carbides if the final cooling temperature is lower than 715°C, and the microhardness of workpiece increases up to 426 HV with degenerated pearlites taking place if the final cooling temperature further decreases. References | Related Articles | Metrics

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Continuous cooling transformation of deformed austenite in highly hole-expandable steels Cai, Ming-Hui (1); Ding, Hua (1); Li, Xiao-Bin (1); Tang, Zheng-You (1) 2008, 29 (11):  1576-1580.  DOI: - Abstract ( 278 )   HTML   PDF (813KB) ( 1286 )   The effects of Si and Mn contents on transformation temperature Ar3, transformed microstructure and mechanical properties of three kinds of low-carbon steels during continuous cooling were investigated. Ar3 rises by 15-25°C when increasing Si content from 0.50% to 1.35%, and it drops by 30-50°C when increasing Mn content from 0.97% to 1.43%. The effect of Mn on Ar3 is more significant than Si. Si stimulates the precipitation of the high-temperature equiaxed ferrite to suppress the bainite transformation, but Mn not only provides the grain refining of transformed microstructure but also stimulates the forming of bainite. The homogeneous and grain refining diphase ferrite/bainite steel (w(Si)=0.56, w(Mn)=1.43) can be obtained after deformed at 850°C and cooled at the rate 30°C/s, of which the tensile strength is up to 654 MPa. References | Related Articles | Metrics

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Preparation of Co-Ni-Cu gradient coatings by CO2 laser cladding on copperplate Dong, Jiang (1); Liu, Fang (2); Chen, Sui-Yuan (1); Liu, Chang-Sheng (1) 2008, 29 (11):  1581-1584.  DOI: - Abstract ( 345 )   HTML   PDF (1037KB) ( 673 )   A 10 kW CO2 laser was used to prepare the Ni-Cu toughness transition coatings on copper substrate with the fast laser cladding process parameters optimized. Then, a Co-base coating was deposited on the transition coating surface by powder fed for laser cladding to form a Co-Ni-Cu functional gradient coating (FGC) whose microstructure is fine, dense and defect-free. The vertical graded distribution of the composition, structure and thermal properties of the coating composed of 3 layers, i.e., the copper substrate, Ni-base transition layer and Co-base working layer, enables the thermal stress during laser cladding to be relaxed, thus avoiding completely the formation of cracks. The reason is that the formation of M7C3/M23C6 type carbides and Co-base solid solution can provide a maximum microhardness value for Co-base working layer up to 655 HV, about 7.3 times higher than copper substrate (90 HV only). Furthermore, the vertical microhardness distribution of the coating reveals the slow increase in gradient from substrate to top layer. It thus verified that the Co-Ni-Cu coating is crack free and hard on surface with tough at core. References | Related Articles | Metrics

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Initial profile design of work roll for hot strip mill Zhao, Xu-Liang (1); Zhang, Dian-Hua (1); Xu, Jian-Zhong (1); Liu, Xiang-Hua (1) 2008, 29 (11):  1585-1588.  DOI: - Abstract ( 271 )   HTML   PDF (431KB) ( 513 )   Introducing the influence function into the analysis of roll's elastic deformation, a design algorithm was proposed for the initial profile of work roll on hot strip mill. It was found that the reasonable strip crown distribution at entry and exit of each and every finishing stand plays an important role in the initial profile design of work roll. And a strategy was proposed to determine such a distribution. The work roll's initial profiles of 1250 mm HSMs in tandem were designed and optimized by the proposed algorithm. The results of in-situ tests showed that the measured strip crowns meet the requirements of target crown, thus verifying the reasonability of the algorithm. References | Related Articles | Metrics

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Experimental study on optimization of electromagnetic stirring parameters for round billet continuous casting molds Zheng, Shu-Guo (1); Zhu, Miao-Yong (1); Yu, Hai-Qi (1); Zeng, Xiao-Ping (2) 2008, 29 (11):  1589-1592.  DOI: - Abstract ( 311 )   HTML   PDF (418KB) ( 968 )   Experiments for optimizing the electromagnetic stirring process parameters of a round billet continuous casting mold were performed, of which the current intensity and frequency were optimized. The results showed that the quality of round billets is not so good under working current/frequency; in which the distribution rates of Grade 2.0 surface blowhole, Grade 1.0 shrinkage and Grade 1.5 central porosity are all 14.28%. With the increasing current intensity from 280 A to 300A during stirring process, the rate of equiaxial grain zone increases by about 16% and it tends to remain unchanged if the current is up to 300 A. The quality of round billets becomes poor when the current intensity increases from 300 A to 320 A. The optimized mold electromagnetic stirring (M-EMS) parameters are given through some tests. References | Related Articles | Metrics

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Effect of raw material mixture ratio on leaching and self-disintegrating behavior of calcium aluminate slag Wang, Bo (1); Yu, Hai-Yan (1); Sun, Hui-Lan (1); Bi, Shi-Wen (1) 2008, 29 (11):  1593-1596.  DOI: - Abstract ( 288 )   HTML   PDF (1656KB) ( 519 )   The calcium aluminate slag was synthesized by adjusting the raw material mixture ratio of CaO, SiO2 and Al2O3 through the calcinations at 1500°C for 1 h with 5°C/min cooling rate, where the main phases were γ-2CaO·SiO2 and 12CaO·7Al2O3. The effects of C/A (the molar ratio of CaO to Al2O3, excluding the CaO synthesized with SiO2 to form 2CaO·SiO2) and A/S (the mass fraction ratio of Al2O3 to SiO2) on the phase compositions and self-disintegrating behavior were investigated by XRD and a laser particle size analyzer. The results indicated that 2CaO·Al2O3·SiO2 is formed when C/A<1.5, which is difficult to leach Al2O3 thus reducing the leaching rate and self-disintegrating behavior of the slag. The increase in C/A ratio can inhibit the formation of 2CaO·Al2O3·SiO2, and the leaching rate and self-disintegrating behavior of the slag become better when C/A=1.6-1.9. The ratio A/S has little effect on the phase composition, and the leaching rate and self-disintegrating behavior of the slag become better when A/S=1.0-2.5. However, the leaching rate will decrease if the self-disintegrating behavior is degraded when A/S>2.5. As a result, the raw material mixture ratio of calcium aluminate slag in pure system is regarded as proper if C/A=1.6-1.9 and A/S=1.0-2.5. References | Related Articles | Metrics

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Effect of pH value on activation of bioleaching bacteria and dearsenification of gold ore concentrates Cui, Ri-Cheng (1); Yang, Hong-Ying (1); Zhang, Gu-Ping (2); Fan, Jin (1) 2008, 29 (11):  1597-1600.  DOI: - Abstract ( 270 )   HTML   PDF (1011KB) ( 518 )   The activation of bacteria and dearsenification of high-As gold ore concentrates for leaching were studied experimentally the way there were six different initial pH gradients set in shaking flasks, i.e., 1.3, 1.5, 1.7, 1.8, 1.9 and 2.1. In the phase of bacterial activation, the bacteria HQ-0211 in the range from 1.3 to 1.9 are more adaptable to activate faster with better oxidation effect. In the phase of dearsenification of high-As gold ore concentrates, the optimum initial pH value for bioleaching is in the range from 1.7 to 1.9, with short stagnation and fast oxidation. When the pH value becomes higher, e.g., up to 2.1, the bacteria will quickly come into their decline phase, so unavailable to bioleaching. With the lower initial pH value in the range from 1.3 to 1.5, the bacteria will fit the long stagnation phase with slow oxidation/dearsenification. References | Related Articles | Metrics

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Influence of La-doping on the structural and electrical properties of Bi2Sr2CaCu2O8+δ compounds Zhang, Ying (1); Li, Mao-Lin (1); Yang, Hua-Zhe (1); Qi, Yang (1) 2008, 29 (11):  1601-1604.  DOI: - Abstract ( 229 )   HTML   PDF (376KB) ( 519 )   The powdered (Bi1-xLax)2Sr2 CaCu2O8+δ superconducting compound were prepared from Bi2212 (Bi2Sr2CaCu2O8+δ) by sol-gel technique with trace La doped in Bi site. The changes in the structure and electrical conductivity due to the La doped as substitute for part of Bi were investigated. The La-doped samples were prepared with metal nitrates as starting materials and ethylenediaminetetracetic acid (EDTA) as chelating agent, in which the range of La-doping content was from 0.01 to 0.09. Thermal analysis (TG-DTA) and X-ray diffraction were employed to investigate the chemical reaction process and structural changes of the samples. The resistance measurements were carried out with a conventional four-probe method. Structural analysis showed that the powdered phase remains orthorhombic Bi2212 structure though the crystal axes a and b lengthen and c shortens. And the electrical conductivity of Bi2212 phase changes obviously with increase in La content doped, as shown by the R-T curves. References | Related Articles | Metrics

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Reliability analysis of slowly variable mass rotor system with rubbing Su, Chang-Qing (1); Zhang, Yi-Min (1) 2008, 29 (11):  1605-1608.  DOI: - Abstract ( 271 )   HTML   PDF (1376KB) ( 526 )   With the dynamic equations developed for slowly variable mass rotor system and its shaft stiffness, damping, eccentricity and radial stiffness of stator taken as random parameters, the stochastic responses of the rotor system are studied systematically by means of matrix perturbation theory, Kronecker algebra, matrix differential calculus and theory of random vibration. According to the stress-strength interference model, a reliability model of slowly variable mass rotor system with rubbing is developed. The reliability of the rubbing happening to the rotor system is obtained by way of statistical fourth moment and Edgeworth series, with the numerical solutions and reliability curves given. References | Related Articles | Metrics

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Discretized modeling process of reliability of multi-state mechanical systems Qian, Wen-Xue (1); Yin, Xiao-Wei (2); Xie, Li-Yang (1) 2008, 29 (11):  1609-1612+1632.  DOI: - Abstract ( 273 )   HTML   PDF (937KB) ( 696 )   It was found that there is a discrepancy between theory and practical effect when applying the conventional reliability assessment based on binary logic to the multi-state mechanical systems, especially the result of its application is unsatisfactory. A new discretized modeling process is therefore proposed on BBN (Bayesian belief networks) basis for the reliability of multi-state mechanical systems, since BBN is featured with bidirectional reasoning function for uncertainty and graphic display. The discretized BBN model is developed the way the nodes in BBN and the multi-states of all components in discrete system should be determined to give the probability of each and every state, then the CPD (conditional probability distributing) is used to describe the relationships between different states so as to express the states of relevant nodes. In the model the complex computation due to various equations in earlier works can be avoided with the number of components unlimited. An example is given and the analyzing results show the effectiveness and favorableness of the discretized BBN model if using it to assess the reliability of a multi-state mechanical system. References | Related Articles | Metrics

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Reliability analysis of dependence-failure system for wire cables Hao, Guang-Bo (1); Xie, Li-Yang (1); Huang, Xin-Xin (1); Li, Li (1) 2008, 29 (11):  1613-1616.  DOI: - Abstract ( 243 )   HTML   PDF (145KB) ( 786 )   The reliability of wire cables is modeled analyzing their mechanical properties during applications, thus evaluating the reliability. The cable is simplified to be a parallel-series model first, considering both Weibull effect and Daniels effect on its mechanical properties. Then, an expression of Weibull distribution of the strength of the series system with Weibull effect is deduced from order statistic, and an analysis is made to the strength computation formula of the parallel system Daniels effect and relevant distribution function. Assuming that there is no independence-failure, as a result, the reliability model of wire cables is developed by conditional probability and stepping computation. The result shows that the reliability model developed provides a reference to the reliability design of wire cables with dependence failure revealable. References | Related Articles | Metrics

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Nonequilibrium dynamic assignment model of queuing system and its application in wartime equipment maintenance Yu, Chun-Ming (1); Chi, Yu-Hong (2); Fang, Yan-Dong (2); Liu, Jie (1) 2008, 29 (11):  1617-1620.  DOI: - Abstract ( 232 )   HTML   PDF (287KB) ( 789 )   Task scheduling for wartime equipment recovery/maintenance, as an interdisciplinary project combining the queuing theory, task assignment and dynamic programming, is typically a nonequilibrium dynamic assignment problem to which no simple and valid solution has been found up to now. By virtues of the advantages of dynamic programming and Hungary algorithm, a new way named the three-step method is proposed, i.e., sectional dimensionality reduction, complement patch-cut and elimination-predigestion. Thus, the problem to be solved is transformed into such a problem to which the mode of solution is known. With an attack executed by tank regiment as example, the software Matlab is used to simulate the equipment damage and recovery/maintenance in wartime, and the results verify the feasibility and validity of the method proposed. References | Related Articles | Metrics

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PCA-based method for image matching of workpiece Zhang, Jin-Ping (1); Liu, Jie (1); Li, Yun-Gong (1); Ni, Hong-Qi (2) 2008, 29 (11):  1621-1624.  DOI: - Abstract ( 216 )   HTML   PDF (1271KB) ( 568 )   To speed up the computation for workpiece image matching, a novel PCA (principal component analysis) method is proposed taking the template image as a multi-dimension set of spatial points, to which the PCA is made. Then, the number of principal components is determined to ensure the information reserving rate, thus obtaining the maximum and minimum projection values (MM-vectors) in all directions of those components as well as the serial numbers of rows in corresponding template images. While matching, only the principal component directions corresponding to the rows of the same serial numbers in searching area are needed to be extracted for the computation of projection value so as to form the vectors of projection values. The distances between MM-vectors and the vectors formed by projection values are computed, and whether the two kinds of vectors are matchable should be in accordance to those distances. During the matching an improved genetic algorithm is used for optimization. The matching results of workpiece images show the high optimizing speed and precision of the proposed method, even if the images to be matched are mixed with high decibel noise. References | Related Articles | Metrics

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Dynamic finite element numerical simulation for bearings with deep ball filling slots Li, Chang (1); Sun, Zhi-Li (1) 2008, 29 (11):  1625-1628.  DOI: - Abstract ( 268 )   HTML   PDF (509KB) ( 839 )   A 3-D parameterized finite element model was developed introducing physical elements for the rolling bearings with deep ball filling slots, based on the dynamic contact and explicit dynamics. With the finite element software ANSYS/LS-DYNA and adaptive grid method, a numerical simulation was done for the whole operating process of those bearings, thus revealing the change in contacting stress strain between the inner/outer ring, rolling balls and ball retainer and relevant pressure in distribution. The result showed that the dynamic simulation is reasonable in comparison with the calculation result by Hertz's theory. Then, the effects of the bearing initial error arising from manufacture, rotating speed and load on the dynamic performance of those bearings are taken into account to provide theoretically reliable reference to the calculation of fatigue strength and optimum dynamic design of those bearings. References | Related Articles | Metrics

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Population balance modelling of isothermal vertical upward bubbly flow Wang, Xiao-Dong (1); Cheung, Chi-Pok (2); Tu, Ji-Yuan (2) 2008, 29 (11):  1629-1632.  DOI: - Abstract ( 198 )   HTML   PDF (1280KB) ( 566 )   An averaged bubble number density (ABND) approach was proposed for modelling the population balance of bubbles in a vertical tube under isothermal condition. The population balance was realized by incorporating the ABND transport equation into a commercial computational fluid dynamics (CFD) code ANSYS CFX 10. The coalescence and breakage effects of the gas bubbles due to random collision and impact of turbulent eddies were modeled using the mechanistic model proposed by Hibiki and Ishii. Local radial distributions of void fraction and liquid velocity as the primitive variables in bubbly flow were predicted and compared with the experimental data by Liu and Bankoff. Close agreements between the predictions and measurements demonstrated the capability of the ABND approach in modeling bubbly flow conditions. References | Related Articles | Metrics

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Experimental study on AE activity characteristics of different rock samples Zhao, Xing-Dong (1); Chen, Chang-Hua (1); Liu, Jian-Po (1); Li, Yuan-Hui (1) 2008, 29 (11):  1633-1636.  DOI: - Abstract ( 321 )   HTML   PDF (520KB) ( 1206 )   To reveal the failure/instability mechanism of different rock samples, the acoustic emission (AE) and its location functioning was applied to studing on the rock failure process under uniaxial compression and what role the AE plays in it. The results showed that failure modes of all samples are the same, i.e., the split failure, and the AE functioning to those five kinds of rock samples differs from each other with load increasing under otherwise equal conditions, though their accumulative AE events are similarly few during initial loading step. During loading, the number of AE events is minimum in sandy rock but maximum in granite, and both the numbers in sandy rock and red granite change very clearly with no portent of failure to come. The AE location as a time-of-arrival results are affected by the elastic wave velocity in rock sample. It was found that AE location is unavailable to the samples of sandy rock, black marble and red granite but available to the samples of marble from Dandong and granite from Jinzhou indicating visually the formation and propagation of a crack and how it runs though. A conclusion is thus drawn that AE location functioning relates directly to the attributes of rock samples. References | Related Articles | Metrics

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Study of built-in depth of anchored piles against landslide Zhang, Jun (1); Chen, Zhi-Xin (2); Men, Yu-Ming (2) 2008, 29 (11):  1637-1640+1651.  DOI: - Abstract ( 194 )   HTML   PDF (415KB) ( 914 )   Analyzing an anchored pile against landslide under loading conditions, its built-in depth was studied with a model developed to calculate it. With the solution given to the resistance to earth against the anchoraged pile end under slip plane by ways of passive earth pressure, slip line and elastic wedge, the built-in depth was determined using the model. The calculation model was verified by relevant testing results and discussed in combination with a numerical example chosen properly form engineering practice. The results showed that the calculation model is comparatively reasonable for the built-in depth of anchored piles against landslide. References | Related Articles | Metrics

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Effect of PAAS on dispersion stabilization of SiO2 nanoparticles Niu, Yong-Xiao (1); Wang, Yi (2); Wang, En-De (1); Fu, Jian-Fei (1) 2008, 29 (11):  1641-1644.  DOI: - Abstract ( 495 )   HTML   PDF (739KB) ( 834 )   PAAS (polyacrylate acid sodium) was selected as dispersant to evaluate the dispersion stabilization of SiO2 nanoparticles by a diffraction-based laser granulometric analyzer and identify the state of adsorption of the dispersant on the surface of nanoparticles by an IR spectrometer. The results indicated that adding PAAS can remarkably improve the dispersion stabilization of SiO2 nanoparticles in aqueous solution but degrade it if the added amount of PAAS is oversaturated. If the mass fraction of PAAS remains unchanged, the low pH value of suspension will increase the probability to form the hydrogen bond between SiO2 nanoparticles and PAAS, thus stimulating the adsorption effect of PAAS on the surface of SiO2 nanoparticles so as to improve their dispersion stabilization. References | Related Articles | Metrics

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Studies on acute toxic effects of Cd, Pb and As on photobacterium phosphoreum Zhou, Xiu-Yan (1); Wang, En-De (2); Han, Gui-Chun (3) 2008, 29 (11):  1645-1647.  DOI: - Abstract ( 234 )   HTML   PDF (143KB) ( 782 )   The joint toxicity from equitoxic mixture and the toxicity of single material as cadmium and lead and that of arsenic were tested in lab with the germ Photobacterium Phosphoreum introduced as test samples. Comparing the expected and measured EC50 values, the toxicity enhancement index was used to evaluate the effect of joint toxicity. The single toxicity test results of cadmium, lead and arsenic showed that their EC50 values are 2.411, 1.668 and 0.463 mg/L, respectively, i.e., As>Pb>Cd in toxic effect. For the Cd-Pb joint toxicity from equitoxic mixture, the EC50 value is 0.293 mg/L and the EC50 ratio of expected value to measured one is 6.7, i.e., a synergistic toxic effect. However, for the Cd-Pb-As joint toxicity, the EC50 ratio is 1.3, i.e., a superposed toxic effect. References | Related Articles | Metrics

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Calculation of bearing capacity for bending of prestressed steel reinforced concrete girder Mu, Guang-Bo (1); Wang, Lian-Guang (1); Zhou, Le (1) 2008, 29 (11):  1648-1651.  DOI: - Abstract ( 243 )   HTML   PDF (1167KB) ( 553 )   Investigates the bearing capacity for bending of prestressed steel reinforced concrete(PSRC) members to which the earlier works were different theoretically and experimentally. Some existing construction procedures relevant to PSRC members are briefly described. According to the sectional shape of PSRC and loading force acting on it, the main failure modes and the range of height of compressed region in the sectional area of concrete under limit load are analyzed. The formulae of bearing capacity for bending in different failure modes are thus given, where the neutral axis is passing through the web plate of a PSRC girder. A comparison showed that the values of calculation and experiment coincide well with each other. References | Related Articles | Metrics

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Coordination of three-level supply chain and revenue sharing contract Ji, Shou-Feng (1); Liu, Ming-Jia (1); Ding, Wei (1); Huang, Xiao-Yuan (1) 2008, 29 (11):  1652-1656.  DOI: - Abstract ( 237 )   HTML   PDF (403KB) ( 995 )   The coordination of a three-level supply chain made up of manufacturer, distributor and retailer and a revenue sharing contract is studied in relation to price and random demand. A mathematical model is thus developed to satisfy the conditions for coordination of supplying channels and attain the win-win good among all businesses in the chain. A numerical example is given and the results reveal that the reasonable choice of contract parameters will attain the win-win good among all businesses under the precondition that the total profit of the supply chain has no loss, and the sizes of contract parameters in a reasonable range relate to the bargaining position of a business. References | Related Articles | Metrics

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Analysis of time-dependent land concession expense and policy readjustment of right of use of land Yang, Yao-Dong (1); Guo, Ya-Jun (1); Hou, Fang (1) 2008, 29 (11):  1657-1660.  DOI: - Abstract ( 230 )   HTML   PDF (850KB) ( 554 )   Analyzes the mechanism of land price and the relationship between land price and land concession expense especially the effects of land concession expense and its time-dependent readjustment policy on land price. Assuming that the readjustment policy of land concession expense remains unchanged, it is found theoretically that there is a key point in both the policy and land concession tenure, and the key point has been verified via practical data. Taking the key point as a reference, the validity of land policies can be actually proved. Under conditions that the policy of land concession expense is readjustable and also uncertain, the way to readjust the land concession policy is discussed on the basis of real options in discrete state, thus providing some suggestions for the validity of land policies. References | Related Articles | Metrics

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DEA/AHP-based of virtual enterprise's partners Lu, Ji-Hua (1); Li, Yan (1) 2008, 29 (11):  1661-1664.  DOI: - Abstract ( 269 )   HTML   PDF (929KB) ( 725 )   During the organization of a virtual enterprise the selection of partners directly relates to its business operation performance. Analyzing the general way to select partners, the data envelopment analysis (DEA) algorithm and the analytical hierarchical process (AHP) algorithm are applied sequentially to sorting the partners as candidates of the same type, then the selected partners are ranked and confirmed through comparison and evaluation. A numerical example is given to illustrate the feasibility and validity of the selection method proposed. References | Related Articles | Metrics

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Analysis of information requirement based on topologic space Sheng, Qi-Zhi (1); Zhao, Xi-Nan (1) 2008, 29 (11):  1665-1668.  DOI: - Abstract ( 243 )   HTML   PDF (214KB) ( 563 )   Topologic space theory is used to analyze the customers' requirement in information management mode so as to classify rationally the customers in accordance to their values. The knowledge neighboring domain of each and every customer is composed of one's soft resources such as knowledge, skill, technological know-how, thought style, cultural connotation and credit level, and the topologic space and storeroom the customers will require are built. With an analysis made to the functions involving the informational element in customers' topological space, a development mode is proposed for the requirement of information in topologic space. The mode is available to guide the acquisition, processing, storage, transmission, application and feedback of information for businesses and social organizations. References | Related Articles | Metrics

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Existence of positive solution to a nonlinear second-order three-point boundary value problem Sun, Tao (1); Jiang, Xiu-Qin (1); Duan, Xiao-Dong (2) 2008, 29 (11):  1669-1672.  DOI: - Abstract ( 294 )   HTML   PDF (151KB) ( 621 )   The existence of one positive solution at least to a second-order three-point boundary value problem is studied. Several sufficient conditions for the existence of positive solution are obtained if the nonlinear terms are all superlinear or sublinear or that among them one is superlinear and the another is sublinear, based on the Krasnosel'skii fixed point theorem. The conclusion that the positive solution to a second-order three-point boundary value problem exists only if the nonlinear terms are superlinear or sublinear is thus improved and generalized. References | Related Articles | Metrics