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15 April 2009, Volume 30 Issue 4 Previous Issue    Next Issue
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Stability analysis of a congestion control scheme based on improved Kelly algorithm Zhang, Nan-Nan (1); Jing, Yuan-Wei (1); Wang, Wei (1); Zhang, Si-Ying (1) 2009, 30 (4):  457-461.  DOI: - Abstract ( 229 )   HTML   PDF (282KB) ( 624 )   To the different propagation delays between users in a network, a discrete congestion control scheme initially proposed by Kelly et al is used to improve it through changing the related parameters and introducing the concept of the max-min fairness into it to build a symmetric Jacobian matrix so as to prove that the system is asymptotically stable to any delay, with the range of the corresponding parameters given for valuation. The analysis results showed that the stability condition of the system is therefore unconstrained by any delay. Numerical examples revealed that the system is ensured to converge fast at the equilibrium point. References | Related Articles | Metrics

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Dynamics of jamming transitions in scale-free networks Wang, Dan (1); Yu, Hao (1); Jing, Yuan-Wei (1); Zhang, Si-Ying (1) 2009, 30 (4):  462-465.  DOI: - Abstract ( 196 )   HTML   PDF (314KB) ( 548 )   Incorporating the local traffic information into the shortest path, a routing strategy that is aware of traffic information is proposed, where a controlled parameter is used to balance the weight of waiting time and the shortest path. Adjusting the controlled parameter, the transmittability of network can be optimized. A simulation is performed in a model of scale-free network with different clustering coefficient, and the results reveal that the jamming transition is characterized by two quite distinct phase transitions and that the network capacity depends on the basic attributes of network architecture and routing strategy. Compared to the shortest path, the network throughput by the strategy proposed is all enhanced greatly no matter what the clustering coefficient is in scale-free network, while, the throughput decreases with increasing clustering coefficient in the routing strategy itself. References | Related Articles | Metrics

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Design of a nonlinear robust controller for STATCOM Sun, Li-Ying (1); Feng, Jia-Xin (2); Zhao, Jun (1) 2009, 30 (4):  466-470.  DOI: - Abstract ( 289 )   HTML   PDF (2206KB) ( 648 )   For a single machine-infinite bus system with static synchronous compensator (STATCOM) of which the parameter uncertainty is involved under external disturbance, the problem of robust H∞ control is studied. Storage functions of control system are constructed on the basis of modified adaptive backstepping and Lyapunov methods, with a robust H∞ controller and the parameter substituting law designed simultaneously. With the fact that the damping coefficients are hard to measure accurately in the internal disturbance emphatically considered, the proposed controller is able to not only keep the nonlinearity of power system and the real-time parameter estimation but also constrain the influences of disturbance on system output. The simulation results verified the effectiveness and advantages of the proposed controller. References | Related Articles | Metrics

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Non-fragile robust H∞ control for a class of switched nonlinear systems Li, Li-Li (1); Feng, Jia-Xin (2); Zhao, Jun (1) 2009, 30 (4):  471-474.  DOI: - Abstract ( 252 )   HTML   PDF (317KB) ( 688 )   The non-fragile robust H∞ control problem is investigated for a class of uncertain switched nonlinear systems with additive gain variations. A design scheme is then given to the non-fragile feedback controllers with their switching law proposed. With the multiple Lyapunov functions used, the switching between subsystems makes the switched nonlinear systems asymptotically stable with H∞-norm bound for all allowable uncertainties. Thus, the sufficient condition solvable to the problem doesn't depend on the Hamilton-Jacobi inequalities. This method is suitable for the case where none of subsystems is asymptotically stable. Then, as a special application, a feedback strategy is proposed to solve the standard non-fragile robust H∞ control problem for non-switched nonlinear systems when no single continuous controller is effective. An example is given to verify the effectiveness of the proposed method. References | Related Articles | Metrics

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Adaptive synchronization of a class of chaotic neural networks with mixed time-varying delays Liu, Zhao-Bing (1); Zhang, Hua-Guang (1); Yang, Dong-Sheng (1) 2009, 30 (4):  475-478.  DOI: - Abstract ( 263 )   HTML   PDF (327KB) ( 574 )   Based on Lasalle invariance theorem of differential equations and adaptive dynamical feedback technique, the adaptive synchronization of a class of chaotic neural networks with fully unknown parameters and mixed time-varying delays is investigated, and as a result, a well-designed method is given to ensure the synchronization of two chaotic neural networks which are of the same structure and fully unknown parameters. Under the action of the adaptive control law, the synchronization and parametric identification can be done simultaneously. The controller designed is simple and easy to implement. Simulation examples are given to verify the effectiveness of the proposed method. References | Related Articles | Metrics

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Tracking control of a class of delay stochastic distribution system Fu, Jie (1); Zhang, Hua-Guang (1); Wang, Ying-Chun (1) 2009, 30 (4):  479-483.  DOI: - Abstract ( 285 )   HTML   PDF (311KB) ( 513 )   Based on a generalized PI controller, a tracking control approach is proposed to the control of non-Gaussian stochastic distribution systems with input delay. Introducing the B-spline expansion and nonlinear dynamic weight delay model to establish the relation between probability density function (PDF) and control input, the problem of PDF tracking control is transformed into that of nonlinear dynamic weight tracking control. Then, based on linear matrix inequality (LMI) technique, the sufficient condition for stochastic distribution systems with time delay is derived to ensure the tracking performance. Simulation results show the effectiveness of the proposed approach. References | Related Articles | Metrics

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Compensation control model of strip head thickness in unsteady rolling state Hao, Pei-Feng (1); Qiang, Ju-Xing (2); Xiao, Bao-Shu (1); Wu, Guo-Bin (1) 2009, 30 (4):  484-486.  DOI: - Abstract ( 278 )   HTML   PDF (260KB) ( 745 )   The self-adaptive control was investigated in case that a weld line of tandem cold rolled strip work-piece is passing through a roll gap under conditions that there is no disturbance to the AGC system. The adaptive adjusting models were therefore developed for each and every roll gap on different mill stands. The application results of these models showed that the stability and control accuracy are both improved in the unsteady rolling state with the thickness fluctuation of strip head decreased at the exit of all stands, thus shortening the over tolerance length of products and raising the rate of finished products. References | Related Articles | Metrics

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A new time domain arc model for arc furnace Wang, Yan (1); Mao, Zhi-Zhong (1); Li, Yan (1); Tian, Hui-Xin (1) 2009, 30 (4):  487-490.  DOI: - Abstract ( 300 )   HTML   PDF (201KB) ( 1018 )   Because of the nonlinearity of arc, numerous high-order harmonics will come to occur in the arc furnace operational process and can result in voltage fluctuations and flicker in the power network. To solve the above adverse problems, a new time domain arc model for arc furnace is developed, which is based on the physical mechanism of arc and takes the arc conductance as the state variable to express the model in terms of a nonlinear differential equation. In addition, the method to calculate the model parameters is given. The arc model can fully account for changes in the different parameters of the electrical power system by adjusting arc model parameters. The simulation results showed that the output arc voltage/current calculated from the model is basically in conformity with the voltage/current measured in situ, thus verifying the validity of the new arc model. References | Related Articles | Metrics

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Cooperative reconfiguration of a reconfigurable mobile robot Wu, Cheng-Dong (1); Liu, Tong-Lin (2); Li, Bin (2); Liu, Jin-Guo (2) 2009, 30 (4):  491-494.  DOI: - Abstract ( 212 )   HTML   PDF (517KB) ( 697 )   The cooperative reconfiguration of the mobile robot AMOEBA-I is presented via developing a mathematical model of relevant robot system to analyze theoretically the cooperative reconfiguration among every module and corresponding motion characteristics. The change in current is investigated when three modules are in the process of cooperative reconfiguration, thus implementing the transform between three specific configurations. The features of such a cooperative reconfiguration are compared through theoretical analysis and experiments, and the experimental results verifies the validity of the cooperative reconfiguration on various ground surfaces. References | Related Articles | Metrics

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Heuristic method for schedule pacing control during composite multi-plate rolling Yu, Chun-Yue (1); Wang, Cheng-En (1); Xu, Mei-Rong (1) 2009, 30 (4):  495-498.  DOI: - Abstract ( 255 )   HTML   PDF (265KB) ( 633 )   The aim of schedule pacing control during composite multi-plate rolling is to make the plate rolling more automatic and increase the mill utilization. Analyzing the characteristics of composite multi-plate rolling process, three modes of the process are classified, i.e., equal-interval alternating, symmetric-interval alternating and grouped alternating. Thus the characteristics and feasible conditions for each of the three modes are described with the formulae of optimum time interval for starting rolling operation and mill utilization both given. Taking account of the restriction of mill table length, the parameters relevant to the formulae are adjusted properly to provide a heuristic method for pacing control. The computation results showed that the proposed method is more accurate than existing method with wider applications. References | Related Articles | Metrics

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Congestion control of ATM networks with multiple bottlenecks Ren, Tao (1); Qu, Rong-Xia (1); Jing, Yuan-Wei (2) 2009, 30 (4):  499-502.  DOI: - Abstract ( 229 )   HTML   PDF (385KB) ( 674 )   Based on the ATM network model with multiple bottlenecks, an explicit rate controller for ABR traffic is designed to solve the congestion problems due to such networks. The sufficient condition for the stability of the closed-loop system is presented, and an algorithm for changeable number of ABR users is given to the real-time estimate of the number of controllable ABR users. The numerical simulation done on different network conditions showed that the proposed algorithm is able to not only overcome the adverse effect caused by multiple round-trip propagation delays but estimate the number of controllable ABR users exactly with high robustness. References | Related Articles | Metrics

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Euler method based route choosing strategy for the vehicles in container yard Li, Dong (1); Wang, Ding-Wei (1) 2009, 30 (4):  503-506.  DOI: - Abstract ( 216 )   HTML   PDF (1170KB) ( 471 )   Discusses the model or strategy developed by Ye et al for improving the production efficiency via container yard where only few narrow paths are provided for the lots of vehicles. Then, the Euler method is introduced into the path-resource-orientated study on the control and decision-making of vehicles' route choosing in a container yard. In this study whether a path is unimpeded or not can be predicted spatially and temporally for vehicles which will therefore travel along a path that is unimpeded and comparatively shorter. Testing results showed that the congestion time and total operational time will both be clearly shortened if the route is chosen according to the proposed strategy in comparison to that developed by Ye et al. References | Related Articles | Metrics

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Evolution mechanism of internet macroscopic topology based on protocol analysis Luo, Gui-Lan (1); Zhao, Hai (1); Zhang, Jun (1); Liu, Zheng (1) 2009, 30 (4):  507-509.  DOI: - Abstract ( 223 )   HTML   PDF (817KB) ( 512 )   The evolution mechanism of IMT (Internet macroscopic topology) was studied in view of protocol. Analyzing mathematically the theory of protocol, a power-law star-like fractal topological reproducibility in IMT was obtained. A protocol-based mathematical model of IMT was developed according to physics and graph theory, by which the formula of topological reproducibility coefficient was deduced from transfer delay in network to determine the topology formation mechanism. Simulation tests were conducted to analyze the time sensitivity of the proposed model, and the results showed that the formation of Internet is a "ecological" evolution process from ordered simplicity to disordered complexity. Such a process can be attributed to that the limit value of the sum of topological reproducibility coefficients is a definite constant and, essentially, the design principle is to substitute the unlimited space of protocols for limited time effect. References | Related Articles | Metrics

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Design and implementation of communication protocol stack based on WORIX in WSNs Zhu, Jian (1); Zhao, He (1); Zhao, Hai (1); Xu, Jiu-Qiang (1) 2009, 30 (4):  510-513.  DOI: - Abstract ( 212 )   HTML   PDF (845KB) ( 499 )   The design of communication protocol stack in WSNs is firstly studied with the operating system-WORIX we developed. The design objective of communication protocol stack is finished according to the characteristic of WSNs, and the communication protocol stack which satisfy the applications of WSNs in WORIX is implemented. The protocol stack comprises three routing protocols. Through experimental analysis, the validity of the protocol stack is verified, and the performance of the three routing protocols is compared with each other. Finally, the occasions where each of the three protocols is applicable are pointed out. References | Related Articles | Metrics

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A new board representation method for k-in-a-row games with its application to Connect6 Xu, Chang-Ming (1); Ma, Zong-Min (1); Xu, Xin-He (1) 2009, 30 (4):  514-517.  DOI: - Abstract ( 484 )   HTML   PDF (340KB) ( 1624 )   A new method is proposed to improve the efficiency of the representation of the game situation, based on the pattern to describe the relationships among stones on a k-in-a-row game position. It has been used successfully in our Connect6 program (NEUConn6) to not only describe the state of a position efficiently but also cater for the incremental updating. This method can transform some online calculations into offline. Furthermore, it is a natural way to integrate the game knowledge with the data structure. Not limite to Connect6, the method can be adopted in other k-in-a-row games. References | Related Articles | Metrics

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A new dynamic routing/wavelength assignment algorithm in ASON Du, Li (1); Meng, Yan-Lou (1); Bi, Xiao-Hong (1) 2009, 30 (4):  518-521.  DOI: - Abstract ( 199 )   HTML   PDF (930KB) ( 656 )   Considering the conditions that the nodes are unable to convert the wavelength and that the number of multiplex wavelengths is limited in optical fibres, a new routing/wavelength assignment (N-RWA) algorithm is proposed to solve dynamically the routing and wavelength assignment problem for the arrival of service request. In the new algorithm a rational fitness function is designed taking account simultaneously of the number of hops in a lightpath and the current network conditions and the genetic algorithm is in combination with least influence wavelength assignment algorithm, thus improving the conventional RWA algorithm. Simulation results showed that N-RWA can significantly reduces the blocking probability in comparison with the conventional RWA algorithm with balanced load kept on in the whole network. References | Related Articles | Metrics

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A novel PTS PAPR reduction algorithm with low computational complexity in OFDM system Gao, Jing (1); Wang, Jin-Kuan (1); Xie, Zhi-Bin (1) 2009, 30 (4):  522-525.  DOI: - Abstract ( 246 )   HTML   PDF (273KB) ( 761 )   PAPR (peak-to-average power ratio) is the basic barrier to the practical application of OFDM system. To solve this problem, a novel PTS (partial transmit sequence) algorithm based on improved simulated annealing PTS (IMSA-PTS) is proposed, where the improved SA optimization approach is used to search the optimal combination of phase factors so as to avoid the local minimum due to the search for phase factor and acquire the minimum PAPR signal from all the states occurring in exhaustive search with unchanged simulated annealing process. Simultaneously, a threshold value is set to improve the convergence rate so as to reduce the computational complexity significantly. Simulation results showed that the proposed algorithm can provide favorable PAPR reduction with low computational complexity. References | Related Articles | Metrics

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On the SPIT detection and prevention method based on feedback judgement He, Guang-Yu (1); Wen, Ying-You (1); Zhao, Hong (1) 2009, 30 (4):  526-530.  DOI: - Abstract ( 218 )   HTML   PDF (293KB) ( 536 )   To resolve the SPIT hidden trouble in the ALL-IP fusion network, a detection/prevention method based on feedback judgement is proposed. Introducing the participation of end users and combining the trust with reputation mechanism, either the direct or indirect information feedback can be utilized simply and effectively without loss. The improved inference algorithm for trustworthiness and reputability fully embodies the distribution characteristics of SPIT behavior and reflects the weighting relation between different influencing factors on judged result. In addition, the incremental learning algorithm provides the real-time trustworthiness and reputability and the fusion of them adjusts their individual role in feedback judgement dynamically. Experiment and analysis results showed the high accuracy and sensitivity of the proposed method, by which the SPIT can be detected and prevented efficiently. References | Related Articles | Metrics

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Optimization based on polychromatic graph theory for products' configuration model and prototype system Zhao, Kai (1); Yu, Tian-Biao (1); Tang, Liang (1); Wang, Wan-Shan (1) 2009, 30 (4):  531-534.  DOI: - Abstract ( 542 )   HTML   PDF (962KB) ( 559 )   Based on the theory of polychromatic graphs, a configuration model was developed for product mix with a mathematical model provided to establish accurately the configuration relationship between different complex product mix. Then, an improved ant colony algorithm was applied to the model for optimal solution, thus developing a prototype configuration/management system based on the model. The results indicated that the configuration model developed on the basis of polychromatic graph theory was able to describe accurately the configuration information, attributes of products and assembling relation between different complex product mix. Furthermore, the prototype system developed enabled the design of complex products to be parallelized, therefore, a new way was given to the collaborative design for users. References | Related Articles | Metrics

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Analysis of optimum strategy using lanchester equation for naval battles like trafalgar Chen, Xiang-Yong (1); Jing, Yuan-Wei (1); Li, Chun-Ji (2); Liu, Xiao-Ping (1) 2009, 30 (4):  535-538.  DOI: - Abstract ( 372 )   HTML   PDF (194KB) ( 1113 )   The strategy analysis based on mathematical description for a battle usually stresses the consistency of the outcome of a battle with the strategy schemed for it. However, as a whole, the decision-making analysis of the battle disposition is rarely involved, such as force grouping and allocation. Taking the historically famous Trafalgar naval battle as example and virtual background with some reasonably military settings given, the Lanchester square equations are introduced in combination with nonlinear integer programming to develop a mathematical model to solve the maximum remaining force problem when the total force is not superior to the enemy. Matlab simulation result and solution to the model both verified the effectiveness of the model we developed and, therefore, the optimal strategy is decided from the exemplification with the naval battle. The reasonable analysis and research on the hybrid game by exemplification with naval battles are also made to complement the war game simulation and foreshadow its outcome. References | Related Articles | Metrics

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Stress distribution on rolls during plate rolling Tian, Yong (1); Hu, Xian-Lei (1); Wang, Zhao-Dong (1); Wang, Guo-Dong (1) 2009, 30 (4):  539-542.  DOI: - Abstract ( 300 )   HTML   PDF (941KB) ( 685 )   To solve the problem of local exfoliation of rolls due to the overstress in the middle of a roll during rolling, the influence function method which a domestic steel plant have used to determine the parameters of a four-high mill so as to analyze its rolls' deformation is introduced in the investigation on the influence of different parameters on the stress distribution along roll axes, such as the diameters and crowns of both back-up and working rolls and the crown and width of workpiece. The results revealed that the changes in roll diameter and crown/width of workpiece have no obvious influence on the stress distribution. However, the change in crown of the back-up roll especially of the working roll affects greatly the stress distribution, which is the main cause for the edge exfoliation of rolls. References | Related Articles | Metrics

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Initial velocity field for solution to strip rolling process by rigid plastic FEM Mei, Rui-Bin (1); Li, Chang-Sheng (1); Liu, Xiang-Hua (1); Zhang, Guang-Liang (2) 2009, 30 (4):  543-546.  DOI: - Abstract ( 276 )   HTML   PDF (435KB) ( 812 )   The rolling force in strip rolling process was solved nonlinearly by the program we developed via the 2D compressible rigid plastic FEM. With the aim of keeping the calculation accuracy unchanged and shortening calculating time, the influence of initial velocity field on calculating time and calculated results were discussed, where the initial velocity field was set differently by the primary, G function or improved refined mesh methods. It was founded that the calculated values of rolling force conform well to the measured values and meet the required accuracy. The relative calculation error can be controlled within 3% by any of the three methods. The initial velocity field affects little the solution to rolling force. In comparison with the primary method, the iteration steps in the G function and improved refined mesh methods are fewer. Because solving the equation sets is necessary, the time required for calculating the initial velocity field set by G function method is the longest one. As to the initial velocity field set by the improved refined mesh method, the calculating time is shortened due to decreased iteration steps with calculation accuracy unchanged, thus improving the calculation efficiency and solution stability. References | Related Articles | Metrics

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Investigation on jerky measurement of shape of hot rolled strip on 4-high mill Hu, Yu (1); Gong, Dian-Yao (1); Xu, Jian-Zhong (1); Liu, Xiang-Hua (1) 2009, 30 (4):  547-550.  DOI: - Abstract ( 287 )   HTML   PDF (351KB) ( 563 )   A jerky measurement of the shape of hot rolled strip was done on the 6-stand 4-high hot strip mill in a certain domestic steel plant, based on an experimental scheme. Then, the values of interstand workpiece crown, rolling force, roll bending force and actual curved surface of roll profile were measured at each and all pass, in the hot strip rolling process. Introducing the simulation software based on influence function method for the elastic deformation of a 4-high mill system into computation of workpiece shape control process, the reason why the calculated average crown values of rolls are different from the relevant setup parameters are discussed and compared. It was found that the calculated and measured values of the interstand transverse thickness distribution of workpiece are in good agreement with each other. References | Related Articles | Metrics

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Influence of austenization holding time on the pearlite in Fe-0.12%C alloy under high magnetic field Song, Jian-Yu (1); Zhao, Xiang (1); Gong, Ming-Long (1); Zuo, Liang (1) 2009, 30 (4):  551-554.  DOI: - Abstract ( 237 )   HTML   PDF (460KB) ( 469 )   The influence of austenization holding time on the morphology of pearlite in Fe-0.12%C alloy under high magnetic field (12 T) was investigated by optical microscopy. It was shown that the tendency that the long axis of the pearlite colonies is parallel and elongated along the magnetic field direction under the high magnetic field increases with the prolonging holding time for austenization. Under the conditions that the holding time for austenization and magnetic field both remain unchanged, the area fraction of the pearlite in the sample whose plate plane is parallel to the magnetic field direction is less than that in the sample whose plate plane is perpendicular to the magnetic field direction, and tendency that the long axis of the pearlite colonies is parallel to and elongated along the magnetic field direction is weaker. References | Related Articles | Metrics

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Synthesis and magnetization characteristics of Fe3O4 nanoparticles Shen, Yong-Feng (1); Zhou, Fang (1); Wang, Yan-Dong (1); Zuo, Liang (1) 2009, 30 (4):  555-558.  DOI: - Abstract ( 267 )   HTML   PDF (256KB) ( 1521 )   The effect of preparation process on the particle sizes and magnetization characteristics of Fe3O4 nanoparticles was characterized by XRD, high-energy XRD, TEM and vibrating sample magnetometer. It was indicated that the average particle size is 32 nm and 7 nm as the results of polyol method and co-precipitation process, respectively. The powdered Fe3O4 nanoparticle samples prepared by two methods showed that the saturated magnetization, remanent magnetization Mr, coercive force Hc are 6.8 × 10-3 A/m (8% lower than that of bulk samples), 4.2 × 10-3 A/m, 1.43 × 10-2 T and 3.3 × 10-4 A/m (about 96% lower than that of bulk samples), 0.0 A/m, 0.0 T, respectively. All these reveal that the size effect causes the occurrence of superparamagnetism, and that the particle size and magnetization characteristics of powdered Fe3O4 relate closely to its preparation process. References | Related Articles | Metrics

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Magnesium β-Ca3 (PO4)2 bioceramic coatings synthesized by sol-gel method Qi, Guo-Chao (1); Xu, Ni-Jun (2); Liu, Chun-Ming (1) 2009, 30 (4):  559-562.  DOI: - Abstract ( 492 )   HTML   PDF (424KB) ( 955 )   The β-Ca3 (PO4)2 (β-TCP) bioceramic coatings containing magnesium were synthesized with sol-gel method after sintering at 600°C. The results showed that CO32- group is incorporated into the β-TCP crystal structure to implement B-type replacement, i.e., the CO32- group partly replaces the PO43- group in the crystal structure. A nascent osten lamella forms on the surface of β-TCP coating in the bioactivity test through soaking the coatings in simulated body fluid (SBF). It means that the coatings have good bioactivity and are expected to be widely used as artificial bone materials in the future. References | Related Articles | Metrics

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Effect of La2O3 addition on synthesis of SiC-ZrO2 composite with zircon as starting material Ma, Bei-Yue (1); Yu, Jing-Kun (1); Zhu, Qiang (1) 2009, 30 (4):  563-566.  DOI: - Abstract ( 264 )   HTML   PDF (937KB) ( 556 )   A phases diagram of predominance area of the Si-C-O system at 1530°C was plotted according to the correlative thermodynamic data. Then, the SiC-ZrO2 composite was synthesized via a carbothermal reduction reaction at 1530°C for 4 h in argon atmosphere, with zircon and carbon black as starting materials and La2O3 reagent as additive. Phase composition and microstructure of the synthesized composite were characterized by XRD and SEM. The results indicated that the increase in additive mass fraction is beneficial to the decomposition of ZrSiO4 and the formation of SiC. It was found that the mass fractions of ZrO2 and SiC in the sample come to the max. values, i.e., 82.8% and 10.8%, respectively, if that of w (La2O3) is 2%. The grain shapes of SiC in the sample are mostly granular and acicular with an average grain size about 200 nm. References | Related Articles | Metrics

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Effect of additive agents on lime desulfurization of boron-containing molten iron with high silicon/sulfur content Yang, Zhong-Dong (1); Xue, Xiang-Xin (1); Liu, Qi (1); Liu, Su-Lan (1) 2009, 30 (4):  567-570.  DOI: - Abstract ( 546 )   HTML   PDF (362KB) ( 789 )   The effect of additive agents on active lime desulfurization of boron-containing molten iron with high Si/S content was studied with injection method. The results showed that the sulfur content can be lowered from 0.1% to less than 0.005% by adding 0.1% Al and 13 kg/t active lime, and the interfacial reaction layer of lime is mainly composed of calcium aluminate, calcium ferrite and calcium sulfide-they are all in fusion state at 1400°C to benefit the diffusion of sulfur. Thus, the sulfur content decreases from 0.1% to below 0.01% if adding 25%CaCO3 and 3%CaF2 with 15 kg/t active lime. In this way, the high-temperature molten iron is the advantageous condition for lime desulfurization. References | Related Articles | Metrics

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On the ignition-proof behavior of Ca during Mg alloy melting Ji, Hai-Bin (1); Yao, Guang-Chun (1); Liu, Le-Tian (1); Zu, Guo-Yin (1) 2009, 30 (4):  571-574.  DOI: - Abstract ( 262 )   HTML   PDF (465KB) ( 832 )   Investigates the effect of Ca addition on the ignition-proof behavior of 10 kinds of molten Mg alloys, in which the Ca content was 0.5wt%-5.0wt% and Al content 9.0wt%. All the specimens of equal weight taken from those alloys were measured at 700°C for their weight increments due to oxidation, and their oxidized surface morphologies were observed. The results revealed that a dense composite CaO film containing a bit of MgO grows up on alloy surface at high temperature after adding Ca to the alloy, and the film is thus isolated from air to prevent Mg from burning. The ignition-proof effect is favorable if the Ca content in Mg alloy is 3.5wt%. References | Related Articles | Metrics

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Influence of amino trimethylene phosphonic acid on performance of zirconium-titanium films on aluminum alloys Wang, Shuang-Hong (1); Liu, Chang-Sheng (1); Liu, Chuan-Hai (1) 2009, 30 (4):  575-577.  DOI: - Abstract ( 289 )   HTML   PDF (225KB) ( 854 )   The amino trimethylene phosphonic acid (ATMP) was added to the passivation zirconium-titanium aqueous solution to form the passivation films on AA6061 aluminum alloy through dipping treatment for anti-corrosion. The influence of ATMP on the corrosion resistance of the passivation films in 3.5%NaCl solution was studied by electrochemical methods, and the film-forming mechanism and anti-corrosion mechanism were discussed. The electrochemical results show that the corrosion potential especially the corrosion current of the passivation films decreases obviously after adding the ATMP. It reveals that adding ATMP into the zirconium-titanium solution can further alleviate the cathodic reaction of aluminum alloy, thus suppressing the corrosion behavior of aluminum alloy efficiently. References | Related Articles | Metrics

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Impact of gasification parameters on coal gasification in fixed bed with high-temperature air Wang, Lian-Yong (1); Cai, Jiu-Ju (1); Li, Ming-Jie (1); Zhao, Zi-Zhong (1) 2009, 30 (4):  578-581.  DOI: - Abstract ( 203 )   HTML   PDF (403KB) ( 890 )   High-temperature air gasification of coal was experimentally investigated in a fixed bed gasifier with ID 0.2 m. The effects of process parameters, such as the ratio of air actually supplied to that required theoretically for complete combustion in gasification process (α), the ratio of steam to carbon in coal (ns/nc) and air pre-heating temperature, on gasification performance indices to which the high-temperature air/steam is used as gasifying agent were studied. The results showed that the effects of α and ns/nc on coal gasification performance indices are realized essentially by changing the gasification temperature. The value of α and ns/nc should be controlled in the optimal range from 0.23 to 0.25 and from 0.37 to 0.45, respectively. Under the permitted technological conditions, the higher the air pre-heating temperature, the better the gasification process of coal. References | Related Articles | Metrics

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An inversion method of mean beam length from absorbing gas to part of its boundary Cui, Miao (1); Chen, Hai-Geng (1); Xu, Li (1); Wu, Bin (1) 2009, 30 (4):  582-584.  DOI: - Abstract ( 246 )   HTML   PDF (181KB) ( 533 )   An inversion method is presented to calculate the mean beam length from absorbing gas to part of its boundary. The three-point Gauss-Legendre integral expression is applied to getting the mean beam lengths for typical geometrical shapes, and the relevant model is verified by virtue of the data as shown in some earlier works. The mean beam lengths from gas to slab surface in different zones of a walking beam reheating furnace are inversely calculated, and the effect of gas absorption coefficient on the lengths and their modified factors are also studied. The study will benefit the correct calculation of radiative heat transfer in reheating furnace. References | Related Articles | Metrics

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Analysis of vibrating compactor system involving slowly varying parameters of compacted material Xin, Li-Li (1); Liang, Ji-Hui (2); Wen, Bang-Chun (1) 2009, 30 (4):  585-588.  DOI: - Abstract ( 259 )   HTML   PDF (453KB) ( 752 )   A model was developed for a vibrating compactor system with slowly varying parameters of compacted material taken into account. The model was solved asymptotically by piecewise linearization with a numerical simulation done analytically. The YZC-1 vibrating compactor was tested in site and the results were compared with simulation results. It was shown that the model is developed properly and calculation results are basically accurate. In the compacting process the natural frequency of the lower part of compactor increases with increasing stiffness of the material to be compacted and increases gradually with decreasing damping. It is necessary to choose rationally the excitation frequency, since increasing the excitation frequency will cause shake that makes operators very uncomfortable though it can increase the exciting force to improve the compacting effect on road material. In addition, the chaotic motion is also able to improve compacting effect. References | Related Articles | Metrics

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Analysis and evaluation of motion reliability He, En-Shan (1); Sun, Zhi-Li (1); Li, Liang-Qiao (2) 2009, 30 (4):  589-592.  DOI: - Abstract ( 293 )   HTML   PDF (1548KB) ( 584 )   Many failure modes were found in mechanism motion and there is a correlation between different failure modes. In addition, numerical computation is hard to analyze and calculate the system motion reliability. To solve the problem, the correlation coefficients between different failure parameters are acquired according to the data from the simulation of motion reliability, thus giving the formulae of different method to solve the system reliability, including the joint probability density, bounded and conditional probability methods. Then, a comprehensive evaluation was carried out by any of the methods for the motion reliability of a mechanism, and the result showed that the system reliability thus calculated is more accurate in comparison to that calculated with parameters assumed separately. References | Related Articles | Metrics

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Mechanical properties of high modulus asphalt-concrete pavement Ou-Yang, Wei (1); Gu, Wei (2); Wang, Lian-Guang (1) 2009, 30 (4):  593-596.  DOI: - Abstract ( 696 )   HTML   PDF (298KB) ( 2501 )   The relationship between the high-temperature dynamic modulus of intermediate courses of asphalt-concrete pavement and ruts in road was studied. The results showed that increasing the high-temperature dynamic modulus of intermediate courses can effectively reduce the compressive and shearing strain of asphalt-concrete mixture under traffic loading, and that increasing the divergence angle of the mixture to transfer load downwards can avoid the accidents due to road ruts. In addition, the application of modifying dopes to concrete can increase its high-temperature dynamic modulus so as to provide the mixture whose mechanical properties are superior to the SBS modified asphalt mixture. References | Related Articles | Metrics

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Interfacial shear force of prestressed steel-concrete-steel sandwich panel Zhang, Xin-Cai (1); Wang, Lian-Guang (1); Xia, Yu-Min (2) 2009, 30 (4):  597-600.  DOI: - Abstract ( 244 )   HTML   PDF (353KB) ( 558 )   Based on the theory of elasticity, some differential equations were derived to calculate the interfacial shear force of a steel-concrete-steel sandwich panel which is characterized with high rigidity and bearing capacity and small deformation, considering the effects of the stress increment in prestressed reinforcements and slippage rigidity. Moreover, the formulae were also given to calculate the interfacial shear force under symmetrically concentrated load. The calculated results showed that the maximum interfacial shear force takes place at mid-span and decreases gradually along board length, and its value approximates to zero at the end. The shear force increases with increasing connecting stiffness/external load but decreases with increasing area of the panel. The stress increment in prestressed reinforcements affects slightly the interfacial shear force, only about 5%. However, the connector stiffness and external load affect greatly the interfacial shear force. References | Related Articles | Metrics

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A group decision-making method with multi-granularity uncertain linguistic information Liu, Yang (1); Fan, Zhi-Ping (1) 2009, 30 (4):  601-604.  DOI: - Abstract ( 229 )   HTML   PDF (249KB) ( 554 )   To solve the group decision-making problem with multi-granularity uncertain linguistic information, the arithmetic of uncertain linguistic is used to calculate every decision maker's uncertain linguistic information of alternatives. The possibility degree matrices are calculated according to the definition on the possibility degree of comparing uncertain linguistic information. The OWA (ordered weighted averaging) aggregation operator is used to aggregate the derived possibility degree matrices, and the ranking value of each alternative is obtained. Finally, the feasibility and validity of proposed method are illustrated by a practical example. References | Related Articles | Metrics

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Vertical analysis of the inter-industry R & D spillovers in three industries of China Han, Ying (1); Wang, Yan-Hui (1); Gao, Dong-Wei (1) 2009, 30 (4):  605-608.  DOI: - Abstract ( 216 )   HTML   PDF (174KB) ( 889 )   The R & D spillover effect of three industries in 1997, 1999, 2000, 2002 in China was analyzed with Erik Dietzenbacher method. The results showed that the R & D spillover of three industries mainly is passed from the tertiary industry to three industries. Strengthening the contributor effect of the tertiary industry among three industries is the main direction of the government policy. The policy to increase R & D input per unit of output value was suggested so as to strengthen the R & D spillover among three industries. The analysis thus made will benefit understanding the status and characteristics of the R & D spillover among three industries, which is of actual importance to formulation of the policies relevant to taxation and development of three industries. References | Related Articles | Metrics