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15 August 2008, Volume 29 Issue 8 Previous Issue    Next Issue
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Method for touching objects in multi-vehicle tracking Wu, Cheng-Dong (1); Guo, Li-Feng (1); Zhang, Yun-Zhou (1); Liu, Meng (1) 2008, 29 (8):  1065-1068.  DOI: - Abstract ( 314 )   HTML   PDF (368KB) ( 1117 )   Based on the Kalman predictive model and orthogonal projection locating theory, a novel algorithm is proposed to segment the object from overlapped vehicle images, which is partly hidden by other object(s). In the algorithm, a segmentation window is framed for a specific occluding vehicle in binary image by means of the vehicle's historically motion information in time domain and Kalman predictive result, and then the minimal circumscribed rectangle of the vehicle is determined using horizontal-vertical orthogonal projection and dynamic threshold theory. A function is designed to evaluate if the segmentation is reasonable with corresponding results given. Experimental results showed that this algorithm can effectively segment overlapped vehicles from each other and track them steadily with low computational complexity available to meet the requirements for real-time system. References | Related Articles | Metrics

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Adaptive sliding mode control for a class of systems with input time-delay and unmatched uncertainties Wang, Ming-Shun (1); Yu, Bin (1); Gao, Xian-Wen (1) 2008, 29 (8):  1069-1072.  DOI: - Abstract ( 241 )   HTML   PDF (2241KB) ( 611 )   The state transformation is used to convert a system with uncertain and unmatched input time-delay into a delay-free one, with a sliding mode controller designed. To ensure the existence of a sliding mode surface and eliminate the possible effect of the unkown uncertain term on the controller, an adaptive sliding mode controller is further designed. In view of the unmatched and uncertain term, a sufficient condition is derived guaranteeing the delay-dependent asymptotical stability of the system in sliding mode in accordance to the Lyapunov stability theorem. Simulation result shows the feasibility and validity of the method proposed. References | Related Articles | Metrics

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Adaptive robust tracking control for a class of uncertain switched fuzzy systems Zhang, Le (1); Yang, Hong (2); Jing, Yuan-Wei (1) 2008, 29 (8):  1073-1076.  DOI: - Abstract ( 288 )   HTML   PDF (262KB) ( 909 )   Presents a new uncertain switched fuzzy system in which all subsystems are fuzzily uncertain. Differing from the conventional switching fuzzy systems which are all of two-level architecture, the new system consists of several subsystems and they switch on/off each other. Studies the robust tracking control of uncertain switched fuzzy systems by multi-Lyapunov functions. Taking account of the external disturbance whose upper bounds are unknown, the global robust controller and its adaptive law are designed with the relevant switching strategy given to enable the tracking error of the system to approach to zero uniformly asymptotically. Simulation indicates that the transient response of the system is improved when combining the slow adjustment of adaptive parameters with quick adjustment of switching law. References | Related Articles | Metrics

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Multi-mode resource-constrained DTCTP Peng, Wu-Liang (1); Wang, Cheng-En (1) 2008, 29 (8):  1077-1079+1095.  DOI: - Abstract ( 263 )   HTML   PDF (1113KB) ( 695 )   Extending a conventional DTCTP (discrete time-cost trade-off problem) model by introducing the constraint on renewable resources, a new multi-mode resource-constrained DTCTP or MRC-DTCTP model is presented, where the renewable resources are corresponding to project costs by presetting proper resource price and all activities can be executed in a crash mode so as to shorten the time limit originally planned for the project. A branch and bound (B&B) algorithm for solving MRC-DTCTP model is developed and applied to computing the deadline for the project. According to the computation results, an entire time-cost trade-off curve is plotted and the advantages of the MRC-DTCTP model are discussed. References | Related Articles | Metrics

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Optimal control replacing period for spin pack in polyester staple fiber plant Jin, Hui (1); Wang, Jian-Hui (1); Li, Tian-Chen (2) 2008, 29 (8):  1080-1082.  DOI: - Abstract ( 288 )   HTML   PDF (121KB) ( 1114 )   In a polyester staple fibre plant the spin pack is one of the key facilities in the process of polyester staple spinning and its performance directly affects the productivity and fibre quality. The spin packs have to be replaced periodically. The problem is to determine the time that the spin packs should be replaced so as to minimize the total cost in a given planned period, including the operating cost and replacement cost. As an equipment updating problem, it is modeled with a dynamic programming (DP) method given to solve it. The model and algorithm are applied to the actual data collected from a large-scale petrochemistry plant, and the computational results are compared to the data generated manually in the plant to verify the effectiveness of the proposed method. It is found that 6%-10% of the total cost is saved on average. References | Related Articles | Metrics

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Simulation on a new algorithm based on PSO fuzzy clustering for image edge detection Shi, Zhen-Gang (1); Gao, Li-Qun (1); Ge, Wen (1) 2008, 29 (8):  1083-1086.  DOI: - Abstract ( 271 )   HTML   PDF (270KB) ( 659 )   The PSO (particle swarm optimization) and fuzzy C-Mean (FCM) algorithms were combined together to form a new algorithm and it is applied to image edge detection, thus overcoming the two shortcomings of standard FCM algorithm, i.e., sensitive to initial value and easy to fall to local minimum. The new algorithm is developed the way an eigenvector is constructed on the basis of measure theory to describe an edge point information, and each of the pixel points in a gray scale image is regarded as a data sample. The eigenvector of the information on an edge point is constructed by processing the gray level of the pixel point, and a 3-D data set is thus given. Then, the data set is classified by PSO fuzzy clustering algorithm to adaptively detect the image edge points so as to extract an edge. Simulation results showed that the new algorithm is highly antinoise and able to get better image edges with improved precision in edge positioning. References | Related Articles | Metrics

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FBP-based super-short-scan algorithm for local cone-beam tomography Zheng, Han (1); Chen, Zi-Kuan (2); Kang, Yan (2); Liu, Ji-Ren (1) 2008, 29 (8):  1087-1090.  DOI: - Abstract ( 291 )   HTML   PDF (534KB) ( 1043 )   Analyzing the existing super-short-scan algorithms, a new super-short-scan algorithm is proposed for local cone-beam CT (computed tomography) on FBP (filtered-back projection)basis with a scanning mode provided for the new algorithm to implement the piecewise circumferential combination. It is used to exactly reconstruct a volume of interest by using a data set acquired by super-short scan to make the reconstruction insensitive to noise. The cone-beam projection scan with piecewise circumferential combination proposed is such a scanning mode that the half-scan in circular trajectory is in combination with super-short scan, which is beneficial to improving the spatial resolution and image contrast of focal area and especially reducing the roentgen dose to patients. References | Related Articles | Metrics

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Resource request estimation in broadband multimedia satcom system Chen, Jian (1); Wen, Ying-You (1); Zhao, Da-Zhe (1); Liu, Ji-Ren (1) 2008, 29 (8):  1091-1095.  DOI: - Abstract ( 299 )   HTML   PDF (1054KB) ( 697 )   The resource allocation process and time sequence of resource requests in MAC protocol for multimedia satcom are analyzed systematically. Then, considering the long transmission delay between GEO satellite and earth, a resource request estimation algorithm based on traffic prediction is proposed to make up for the traffic deficiency in existing algorithms which are lagging far behind the increasing traffic. Introducing the recording operator into the algorithm to record the resource requests and relevant distribution so as to improve the bandwidth allocation efficiency, the algorithm can decrease the number of request signaling messages to shorten the response time for the request for network resource. LMS (least mean square) prediction is applied to predicting the network traffic so as to weaken the adverse effect of time delay due to long satellite link on request for network resources. The simulation results showed that the algorithm proposed is greatly superior to other existing resource request algorithms in the adaptability under conditions of high loadability and long peak transmission time. References | Related Articles | Metrics

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Conceptual design of trusted mobile platform Chen, Shu-Yi (1); Wen, Ying-You (1); Zhao, Hong (1) 2008, 29 (8):  1096-1099.  DOI: - Abstract ( 257 )   HTML   PDF (505KB) ( 1245 )   Investigating in depth the existing conceptual designs of trusted mobile platforms and technology of the TCG mobile trusted module, a new conceptual design of trusted mobile platform based on the module is proposed, of which the base-band processor is separated from application processor. The trusted region with the application processor as a center is constructed in the design to provide a protected space for computing and storage, thus improving the security, flexibility and reliability of the platform. Analyzing the vulnerabilities of security bootstrapping procedures in existing trusted mobile platforms, an improved procedure is proposed and it is verified according to predicate logic. References | Related Articles | Metrics

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NAT traversal in accordance to SIP based on session border controller Zhao, Bo (1); Wen, Ying-You (1); Zhao, Hong (1) 2008, 29 (8):  1100-1104.  DOI: - Abstract ( 344 )   HTML   PDF (1042KB) ( 1560 )   According to the problems in the present NAT schemes, an NAT traversal in accordance to SBC-based SIP protocol is proposed, which is implemented by relaying simultaneously both the SIP signaling messages and RTP media streams. With the system architecture of SBC illustrated, the NAT traversal process is analyzed in detail under different applications. The results of functional analysis and performance test showed that the proposed NAT traversal in comparison with other conventional schemes is available to implement transparent traversal with no change required for network configuration and improved efficiency provided. References | Related Articles | Metrics

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Improved LMSE estimation algorithm for flat MIMO channel Sha, Yi (1); Wang, Bin (1); Yao, Na (1); Xu, Xiao-Jing (1) 2008, 29 (8):  1105-1107.  DOI: - Abstract ( 290 )   HTML   PDF (196KB) ( 1043 )   Based on the mathematical model of flat fading MIMO channel, the minimum mean square error (MMSE) estimation algorithm was studied with its derivation process given in detail. The LMSE estimation algorithm is so complex that its convergence rate is restricted to a certain extent and becomes slow in applications. To reduce its complexity, the algorithm is simplified mathematically with the inverse operation of first-order matrix cut out. An MIMO system is set up in simulation to provide the curves of estimation performance and those of convergence. The theoretical analysis and simulation results show that no obvious difference is found between the estimated performance of the improved algorithm and that of unimproved algorithm, but the convergence rate of improved algorithm is significantly increased. Thus the simplification is regarded as successful. References | Related Articles | Metrics

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Finding out the ideal PAPR in OFDM system Zhang, Zhen-Chuan (1); Liu, Jiang-Ning (1); Song, Jun-Bao (1) 2008, 29 (8):  1108-1110.  DOI: - Abstract ( 262 )   HTML   PDF (191KB) ( 1012 )   Discusses theoretically the relation between BER and PAPR in an OFDM system which has been processed to decrease PAPR. On conditions that the power amplifier efficiency is ensured, there is a PAPR that enables the BER to be minimum. Such a PAPR is defined as an ideal one but uncertainly a minimum one. What is mentioned above is demonstrated by two existing methods to reduce PAPR, i.e., wave clipping and selective mapping. Taking the former as example that is used to reduce PAPR in an OFDM system, the software MATLAB is applied to simulating the system and the results verify the correctness of the demonstration: the ideal PAPR is available to find out with less BER to improve the system performance. References | Related Articles | Metrics

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Autonomous identification of faulty links for communication networks Zhao, Zhi-Gang (1); Wang, Jian-Hui (1) 2008, 29 (8):  1111-1114.  DOI: - Abstract ( 521 )   HTML   PDF (1148KB) ( 612 )   Conventionally the manual service is often required for fault diagnosis of network links with improper accuracy brought in. So, a full automatic fault diagnosis approach for communication links is proposed as follows. If the path information that which nodes are available or unavailable to communicate with the node(s) taking charge of network management has both been known, a fault diagnosis model is developed in combination with probability computation, by which the node(s) in charge of network management can implement full automatically the real-time identification of the range where the link failures happen most probably. Then, the link failures can be positioned accurately via quick tests. The simulation results showed that this approach is real-time, highly accurate and full automatic with no or few extra bandwidth occupied. References | Related Articles | Metrics

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Analysis of continuous cooling transformation and microstructure of hot-formed GCr15 steel Yang, Hong-Bo (1); Ma, Bao-Guo (2); Zhu, Fu-Xian (1); Liu, Xiang-Hua (1) 2008, 29 (8):  1115-1117.  DOI: - Abstract ( 277 )   HTML   PDF (977KB) ( 695 )   Gleeble1500 thermal simulation machine was used to simulate the hot rolling process of GCr15 bearing steel with the aim to reasonably determine the cooling process after rolling, where the final-pass temperature was 830°C. The dynamic CCT curve was therefore given. Optical microscopy and SEM were employed to investigate the influence of cooling rate on the thickness of pearlite lamella and network carbide precipitation, and the results showed that the thickness of pearlite lamella thins with increasing cooling rate within a certain range of cooling rate, while a coarse pearlite-like structure takes place if the cooling rate is too high. When the cooling rate is about 10°C/s, the pearlite lamella structure is obtainable and the quantity of network carbide precipitation can be decreased efficiently. References | Related Articles | Metrics

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Homogenization treatment of semicontinuous casting ingot of Al-6.5Zn-2.4Mg-2.3Cu aluminum alloy Gao, Feng-Hua (1); Tian, Ni (1); Sun, Zhao-Xia (2); Zhao, Gang (1) 2008, 29 (8):  1118-1121.  DOI: - Abstract ( 265 )   HTML   PDF (382KB) ( 759 )   The constituents in the semicontinuous casting ingot of the super-high strength Al-6.5Zn-2.4Mg-2.3Cu aluminum alloy and how they change in the process of homogenization treatment at 470°C were studied by differential scanning calorimetry (DSC), optical microscopy (OM) and scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX). The results showed that non-equilibrium freezing eutectic containing Al, Zn, Mg, Cu in the ingot not only dissolves into the alloy matrix, but also transforms into S phase (Al2CuMg) in the homogenization treatment process, and the S phase thus formed melts at 490°C in this alloy. During the initial period of the process, the formation rate of S phase is higher than the rate of S phase's dissolution into the alloy matrix, thus resulting in that the quantity of S phase increases at first then decreases to equilibrium value with the prolonged time for homogenization. However, the S phase in the alloy can not be dissolved into its matrix completely. References | Related Articles | Metrics

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Study on corrodibility of hot dip Al-Zn layer passivated with La(NO3)3-doped BTESPT solutions Shan, Feng-Jun (1); Liu, Chang-Sheng (1); Wang, Shuang-Hong (1); Liu, Dong (1) 2008, 29 (8):  1122-1125.  DOI: - Abstract ( 245 )   HTML   PDF (390KB) ( 1006 )   The hot dip Al-Zn layer was passivated with La(NO3)3-doped BTESPT solution in which the layer was dipped at 25°C and cured at 120°C for 30 min, thus forming a passive film on the layer. The structure, surface morphology and corrodibility of the substrate after passivation were studied experimentally. FTIR (Fourier transformation infra-red spectroscopy) showed that the La(NO3)3-doped BTESPT films have been successfully deposited by chemical bonding between the solution and hot dip Al-Zn substrate and by the formation of SiOAl and SiOZn. No obvious difference is found between the components of major organic groups in the passive films deposited and the undoped BTESPT films. SEM results indicated that the films deposited are compact and homogeneous without clear tiny cracks. The EDS (energy dispersive spectrometry) results showed that the films consist mainly of such elements as C, O, Si, S, Al, Zn and La. The test results of corrosion resistance showed that the corrosion potential and current density of the passive films decrease obviously, while the polarization resistance increases. It is therefore proved that the passivisity by La(NO3)3-doped BTESPT is much higher than that without doping in regard to corrosion resistance. References | Related Articles | Metrics

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Study on microstructure and properties of K465 alloy Pei, Zhong-Ye (1); Li, Jun-Tao (2); Zhao, Ming-Han (2); Tian, Yan-Wen (1) 2008, 29 (8):  1126-1129+1134.  DOI: - Abstract ( 447 )   HTML   PDF (1741KB) ( 1093 )   The as-cast microstructure and properties of K465 nickel-base cast superalloy are investigated, as well as they are during heat-treatment. The results showed that the alloy as-cast is composed of γ phase, γ′ phase, (γ+γ′) eutectic and MC carbide, and its average tensile strength and percentage elongation at ambient temperature are 960 MPa and 6.0%, respectively. The creep rupture life under the condition of 975°C/230 MPa is 28.1 h. After the 1210°C/4 h solution treatment followed by air-cooling, the crystal boundary MC carbide partly becomes M6C one with γ′ phase particle size reduced to 0.1-0.2 μm and the tensile strength and elongation at ambient temperature up to 1055 MPa and 4.0%, respectively. The creep rupture life is 50.3 h under the same condition. With 0.02 wt% Mg added in, the grains of MC carbide in the alloy is spheroidized, and the average tensile strength and elongation of the alloy at ambient temperature are 990?MPa and 5.0%, respectively, with a creep rupture life up to 56.3 h under the same conditon. References | Related Articles | Metrics

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Non-physical boundary condition of steady temperature field in continuous casting process Zhou, Zhi-Min (1); Lu, Gui-Min (2) 2008, 29 (8):  1130-1134.  DOI: - Abstract ( 277 )   HTML   PDF (1175KB) ( 729 )   A model of temperature field was developed to describe the continuous casting process. The model of the non-physical boundary condition of temperature field was also proposed by extrapolation technique for the castings out of the mould to get efficient and accurate calculation results of the steady temperature fields. Then, the steady temperature fields of Al-Cu alloys in semi-continuous casting process were calculated using the given models, and the mesoscale temperature field thus determined was taken as the conditions for the simulation of liquid-solid phase transformation. The calculated temperature fields were applied to the multi-scale simulation of the solidification of the Al-10%Cu alloys at different pouring temperatures, thus obtaining the morphology and reasonably distributed grain structure. It was found that the simulated grain size and morphology of near liquidus cast ZL201 alloy is well consistent with experimental results. All the results show that the models developed for temperature field and non-physical boundary condition are applicable to the simulation of steady continuous casting process, especially they can provide correct data of temperature fields as reference for the multi-scale simulation of solidified metal structure. References | Related Articles | Metrics

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Effect of penetration behavior of calcium ferrite melts into hematite on the strength of sinter Jin, Ming-Fang (1); Li, Guang-Sen (1); Jiang, Xin (1); Shen, Feng-Man (1) 2008, 29 (8):  1135-1138.  DOI: - Abstract ( 252 )   HTML   PDF (666KB) ( 922 )   The effects of penetration behavior of the calcium ferrite (CaO·Fe2O3 or CF) melts to which SiO2 or Al2O3 has been added on the sintered hematite as matrix to be penetrated was investigated experimentally, as well as its effect on the compressive and rupture strength of sinter specimens. The results showed that the penetration of the CF-based melts into sintered hematite was suppressed by the additive SiO2 or Al2O3. The sintered hematite with CF to which 2 wt% of SiO2 was added at 1300°C and held for 20 min can offer the highest compression and rupture strength because the melting time of CF melts with SiO2 added in is shorter with penetrability improved, thus forming sufficiently the liquid phase with high liquidity in sintering process to enhance the consolidation effect between adhesion phase and iron ore particles. References | Related Articles | Metrics

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Study on distribution ratio and separation coefficient of cerium and praseodymium in P204-HCl-H3cit system Chang, Hong-Tao (1); Wu, Wen-Yuan (1); Bian, Xue (1); Tu, Gan-Feng (1) 2008, 29 (8):  1139-1142.  DOI: - Abstract ( 326 )   HTML   PDF (1021KB) ( 795 )   The effects of the feed acidity and citric acid (H3cit) concentration on the distribution ratio and the separation coefficient of Ce(III) and Pr(III) and the extraction capacity were investigated in P204-HCl-H3cit system. The result showed that the distribution ratio and the separation coefficient both decrease with increasing feed acidity and increase with increasing citric acid concentration, and the extraction capacity increases with increasing citric acidity concentration in P204-HCl-H3cit system. The mechanism of the increase of the separation coefficient of Ce(III) and Pr(III) was analyzed by FT-IR spectra. When citric acid concentration is 0.25 mol·L-1 and pH value of feed acidity is 1.0, the maximum separation coefficient comes up to 1.71 with maximum extraction capacity 27 g/L. The performance index is therefore proved superior to that in saponified P204-HCl system. References | Related Articles | Metrics

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Preparation and characterization of chitosan oligosaccharide precursor Li, Feng-Hong (1); Zhang, Yu-Hong (1); Du, Yan-Hua (1); Zhang, Bao-Yan (1) 2008, 29 (8):  1143-1146.  DOI: - Abstract ( 296 )   HTML   PDF (777KB) ( 672 )   A simple and convenient procedure for chemoselective protection of the amino groups of chitosan oligosaccharide was developed to prepare N-phthaloyl-chitosan oligosaccharide. It is indispensable to the soluble N-protected precursor to modify chemoselectively the reactions of chitosan oligosaccharide. A series of N-phthaloyl-chitosan oligosaccharide precursors were prepared at different levels of substitution with the same homogeneity of constituents by way of controlling the mole ratio of phthalic anhydride to chitosan oligosaccharide and reaction time/temperature. The level of substitution and molecular structure of the precursors prepared were characterized with FTIR and XRD. The results showed that the level of substitution and affinity of organic solvents both increase with the increasing mole ratio as above. XRD patterns showed that the N-phthaloyl-chitosan oligosaccharide can crystallize though there is a bulky substituent group hung from it. References | Related Articles | Metrics

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Pose error analysis of planar mechanism with joint clearance Zhang, Yi-Min (1); Huang, Xian-Zhen (1); Zhang, Xu-Fang (1); Yue, Gui-Ping (1) 2008, 29 (8):  1147-1150.  DOI: - Abstract ( 298 )   HTML   PDF (1240KB) ( 842 )   The theories of error analysis, optimization and virtual displacement are combined together to discuss the pose error of planar mechanism with joint clearance, and a calculation method is proposed for the pose error of planar mechanism. Based on the principle of virtual displacement, the mapping relation between the original error of a planar mechanism and its output end pose error is analyzed. Then, a mathematical model of the original error that is commonly found in planar mechanism is presented, and the pose error for the output end is also derived. Finally, an extremum expression is explored by virtue of the idea about optimization for the output end pose error. In comparison with other similar methods, the proposed one has the advantages of clean reasoning and high versatility without specifically external force required to act on. References | Related Articles | Metrics

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Dependence-failure reliability analysis based on equivalent damage principle for parallel system Hao, Guang-Bo (1); Xie, Li-Yang (1); He, Xiu-Yun (1) 2008, 29 (8):  1151-1154+1163.  DOI: - Abstract ( 335 )   HTML   PDF (374KB) ( 585 )   Considering the components whose service life accords with the Weibull distribution, the dependent failure of a parallel system comprising two components is analyzed to propose a method to transform the dependent failure into equivalent damage, thus analyzing further the dependent failure. Then, a dependence-failure reliability model based on the transform principle of equivalent damage and full probability formula is developed for the two components' parallel system, and it is verified by the Monte Carlo simulation. The results show that the reliability model of parallel system based on equivalent damage principle can reflect well the dependent failure of the two components and meet the equivalent damage principle. So, it is prior to the model just based on the equivalent probability transform principle and available to provide a new method for the reliability analysis of parallel system of which the service life of its components complies with the Weibull distribution. References | Related Articles | Metrics

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Vehicle dynamics control and its integration with four-wheel steering Zhou, Shu-Wen (1); Yan, Si-Ping (1); Yang, Ying (1); Huang, Ling-Qin (2) 2008, 29 (8):  1155-1158.  DOI: - Abstract ( 591 )   HTML   PDF (522KB) ( 1012 )   Based on ADAMS/CAR a virtual four-wheel steering (4WS) car prototype was developed, then its kinematic characteristics and forced conditions were analyzed in cases of two-wheel steering (2WS) without braking, with rear left wheel braking and four-wheel braking. The results indicated that the steerability is more stable and trackable during rear left wheel braking and four-wheel braking. A comparative analysis was made between the VDC (vehicle dynamics control) integrated with 4WS, 4WS without braking and 2WS, and the simulation results revealed that the steering stability at high speed are ensured by the VDC integrated with 4WS with flexibility improved. The conclusion is important to reduce traffic accidents for cars at high traveling speed. References | Related Articles | Metrics

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Structure sensitivity analysis and optimized design of a certain white bodywork Yang, Ying (1); Zhao, Guang-Yao (1); Meng, Fan-Liang (1) 2008, 29 (8):  1159-1163.  DOI: - Abstract ( 314 )   HTML   PDF (440KB) ( 1499 )   Develops a finite element model to analyze the dynamic/static sensitivities of a certain white bodywork, i.e., the sensitivities of its natural frequency, torsional stiffness and flexural rigidity and mass to the thickness of sheet to make the bodywork, thus finding out the main parts affecting greatly the dynamic and static characteristics of bodywork to optimize its structural design. According to the sizes of contribution the body mass will make to the natural frequency and torsional stiffness and flexural rigidity, an optimal conceptual design is given. This method provides an important reference for improving the dynamic performance of bodywork, lightening its weight and optimizing its design. References | Related Articles | Metrics

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Calculation model of fatigue wear-off in gear engagement Wang, Shu-Ren (1); Yan, Yu-Tao (1); Yin, Wei-Li (2); Ding, Jin-Yuan (1) 2008, 29 (8):  1164-1167.  DOI: - Abstract ( 328 )   HTML   PDF (303KB) ( 1428 )   The process of fatigue wear-off of tooth face in a closed gear drive system is similar to a layered wear-off mechanism. A mathematical model is thus developed to calculate the friction-fatigue wear-off of tooth face in gearing. The wear rate, teeth slippage during each meshing engagement, rotational speed, time for gearing, number of gear pairs in meshing process and the coefficients of teeth face modification, lubrication and loading are all involved in the expression of worn layer thickness. With the methods given to determine all of the parameters required for the calculation model, what the model is applicable to are discussed. The ways to reduce the fatigue wear-off due to meshing teeth faces under different working conditions are found out via the mathematical model describing the physical process of tooth face wear-off. The model proposed is of technological importance to engineering practice and available to provide reference for simulation of wear-off process of gear engagement. References | Related Articles | Metrics

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Outgassing rate of kovar alloy and holding vacuum degree in minisized container Zhang, Shi-Wei (0); Zhang, Zhi-Jun (0); Xu, Cheng-Hai (0); Wang, Li (0) 2008, 29 (8):  1168-1171.  DOI: - Abstract ( 472 )   HTML   PDF (237KB) ( 759 )   To investigate the effect of outgassing from a certain material on holding vacuum degree in a minisized container (10-5 m3), a special testing system was developed with the pressure rise method used. The Kovar alloy with passivated surface was taken as sample and its outgassing rate under given conditions was tested. The results showed that the surface outgassing rate per unit area is in the range from 5.1 × 10-13 to 2.1 × 10-13 Pa·m3·s-1·cm-2 in first 10 hr after baking at 150°C for 2 hr, and the total outgassing throughput per unit surface area is about 2.6 × 10-8 Pa·m3·cm-2 for 40 hr. The outgassing composition consists of H2, H2O, N2 and/or CO, as shown in the spectra by quadrupole mass spectrometry. A mathematic model was developed to describe how the process of surface outgassing affects the vacuum degree in a minisized container with the pressure boost formula calculated. The key influencing factors on the normal performance and service life of the minisized container were investigated to find them so as to improve the method proposed. References | Related Articles | Metrics

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Development of a prototypical tester with gene chips to simulate robot's motion and analysis of its reliability Wang, Dan (1); Jia, Li-Na (1); Wang, Xiao-Guang (1); Li, Ming (1) 2008, 29 (8):  1172-1175.  DOI: - Abstract ( 229 )   HTML   PDF (421KB) ( 806 )   The prototype of a new tester was proposed and conceptually designed on the basis of the hybridization of gene chips resulting from nucleic acid amplification, which integrates the effects of amplification, hybridization, cleaning and testing together. The simulation software ADAMS was applied to the tester to kinematically simulate the virtual prototype of a robot which is just the core part of the tester. The time response curves of robot's swinging arms with gene chip fitted together were then obtained. By means of the principle of kinematic reliability of mechanisms, the reliability of the robot's motion was analyzed with its kinematic precision calculated. The results indicated that the tester can provide well the kinematic precision for either transverse or longitudinal motion of robot, thus verifying the feasibility of the prototypical tester. References | Related Articles | Metrics

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Calculation of smooth factor in GPS level/elevation fitting by hardy function Ma, Hong-Bin (1); Dong, Zhong-Yu (1) 2008, 29 (8):  1176-1178+1191.  DOI: - Abstract ( 293 )   HTML   PDF (182KB) ( 1423 )   The software GLSPA (GPS level simulation process analysis) was numerically applied to the investigation of the effects of different smooth factors in GPS level/elevation fitting by Hardy function on the fitting precision. The results showed that the fitting precision is improved with increasing smooth factor for forward hyperbolic kernel functions but not for all kernel functions, and there is a maximum of smooth factors for inverse hyperbolic kernel function and the fitting precision lowers if exceeding the maximum. To find out smooth factor that is appropriate to all of relevant kernel functions, lots of analog computation and mathematical statistics were done with the results analyzed to propose first a formula to calculate the smooth factor. The formula is available to solve the problem that the fitting precision is unstable because the smooth factors cannot be determined accurately when fitting the GPS level/elevation by Hardy function. References | Related Articles | Metrics

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Numerical simulation of non-steady dust collection process in electric field of electrostatic precipitator Hao, Wen-Ge (1); Pei, Ying-Ying (1); Hou, Ya-Ping (1); Xiong, Hao-Wang (1) 2008, 29 (8):  1179-1182.  DOI: - Abstract ( 350 )   HTML   PDF (1070KB) ( 853 )   Based on the theory of non-steady electrostatic collection of charged particles, the particle migration velocity during the non-steady collection was calculated. According to the mass transfer theory of turbulent flow, an expression of turbulent mixing-diffusing coefficient was derived, and a new boundary condition at counter electrode was deduced on the basis of boundary layer theory. Then, the 2-D turbulent mixing-diffusing equation of particles during non-steady electrostatic dust collection was given in difference scheme by the finite difference method and stepwise super-relaxation iteration method. With the numerical simulation carried out by Matlab, how the mass concentration of dust particles are distributed at different time during non-steady dust collection by ESP (electrastatic precipitator) was obtained, as well as the dust classification efficiency in accordance to the sectional distribution of mass concentration. The comparison between measured and simulated results of different sectional dust concentrations showed that they conform well with each other. A conclusion is thus drawn that the dust collection efficiency calculated in this way is more accurate than that by conventional theoretical calculation. References | Related Articles | Metrics

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Inhibition effect of copper on seed germination and seedling growth of three leguminous plants Cao, Cheng-You (0); Gao, Fei-Fei (0); Shao, Jian-Fei (0); Xu, Hui (0) 2008, 29 (8):  1183-1186.  DOI: - Abstract ( 345 )   HTML   PDF (265KB) ( 1196 )   The inhibition effects of Cu2+ on seed germination and radicle/germ elongation were studied via hydroponical experiment, and the effects of different Cu2+ contents in soil on the length, weight and chlorophyll content of above-ground and underground parts of plants were studied via pot culture experiment. The results revealed that the aqueous solution in which the Cu2+ mass concentration greater than or equal 400 mg·L-1 obviously inhibits the seed germination of the three plants: Medicago sativa, Trifolium pratense and Astragalus adsurgens. The higher the Cu2+ mass concentration, the more obvious the inhibition effect, and the inhibition effect on the first one is lower than that on the other two. In addition, the inhibition effect on the elongation of radicle is higher than that on germ. Excessive Cu2+ content will lower the chlorophyll content in plants with obvious inhibition effect on the growth of above-ground parts of plants. However, the Cu2+ content clearly accelerates the growth of length and weight of the root system of M. sativa and T. pratense, but it inhibits that of A. adsurgens obviously. As a whole, the endurability of M. sativa to Cu pollution is higher than that of the other two plants. References | Related Articles | Metrics

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Transverse stress distribution in locally precompressed concrete beam under anchor slab Zhang, Wen-Xian (1); Zhu, Hong (1); Jin, Shu-Yang (1); Feng, Yang-Fei (1) 2008, 29 (8):  1187-1191.  DOI: - Abstract ( 316 )   HTML   PDF (1341KB) ( 666 )   A physical model of T-shaped beam made from C50 concrete was provided to investigate the prefabricating process of those types of prestressed beams for a bridge, and a compression test was carried out to it on a press. The results showed that how the transverse stress changes in concrete under an anchor slab. With an FEM model developed, the transverse stress was calculated. Comparing the calculated results with tested ones and fitting them, an empirical formula was given to practically solve the transverse stress under anchor slab. Then, the maximum transverse stress and its position can be found out by extremum method. It is confirmed that in detail design the transverse cracks occurring on beam ends can be efficiently restricted if the concrete beam's periphery 30 cm below the anchor slab is constrained to a certain extent. References | Related Articles | Metrics

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New type of building sealants made from bentonite Liu, Xue-Gui (1); Fu, Jian-Fei (1); Shao, Hong (2); Wang, En-De (1) 2008, 29 (8):  1192-1195.  DOI: - Abstract ( 307 )   HTML   PDF (974KB) ( 879 )   A new type of hydrophilic-expansion paste sealants made from bentonite for buildings was developed. Three samples were made from Na-base bentonite mixed with mineral oil and paraffin wax, and the mass fraction of bentonite used is different, i.e., 60%, 65% and 70%. A testing setup was therefore developed accordingly to determine the permeability coefficient so as to work out some properties of the paste sealants under unrestrained conditions, and the results showed that the 24-hour volume expansivities are 211%, 222% and 256% with their permeability coefficients 2.86 × 10-8, 4.15 × 10-8 and 4.78 × 10-8 cm/s, respectively. All samples showed favorable low-temperature flexibility, and the samples whose bentonite content is 65% or 70% have no flowability when heated at 80°C for 2 hr. XRD patterns and SEM images indicated that the bentonite in those samples are clad well by mineral oil, and the interlayer gaps of bentonite basically remain unchanged. It implies that in the samples the hydrophilic expandability of bentonite is kept up with high moldability provided. So, the sealing performance as shown by those samples has come up to the standard for the application to buildings. References | Related Articles | Metrics

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Study on franchising strategy for upstream firm's new products within the framework of vertical restraints Chen, Guo-Hong (1); Wang, Qiu-Fei (2); Li, Kai (1) 2008, 29 (8):  1196-1199+1216.  DOI: - Abstract ( 205 )   HTML   PDF (180KB) ( 694 )   The Cournot quantity competition model is applied to the comparative study on the two technological strategies, i.e., vertical integration and franchise fee, within the framework of vertical restraints if the upstream firm supplies new products through technological innovation with cost reduced. It is found that the upstream firm's profits resulting from vertical integration is always higher than that from franchise fee if the new products cause the downstream firm's marginal cost less reduced. And the upstream firm's profits resulting from franchise fee is higher than that from vertical integration under conditions that the quality of the new products supplied by downstream firm remain unchanged if the new products cause the downstream firm's marginal cost more reduced. However, when the quality of the new products supplied by downstream firm cannot be kept unchanged, the upstream firm's profits resulting from vertical integration is higher than that from franchise fee. As to the social welfare, it will be improved further only if the upstream firm chooses the strategy of franchise fee when the new products slightly affect the cost reduction. References | Related Articles | Metrics

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Lumped mass finite element method for parabolic problem on rectangular mesh Li, Zheng (1); Zhang, Tie (1); Li, Chang-Jun (1) 2008, 29 (8):  1204-1208.  DOI: - Abstract ( 246 )   HTML   PDF (346KB) ( 802 )   The property of the lumped mass finite element method (LMFEM) on rectangular mesh is investigated to solve a typical parabolic problem, i.e., the heat transfer equation. The integral formula of the bi-linear finite element basis function on the rectangular mesh is given to discuss the error estimation for LMFEM. It is found that LMFEM has the equivalent approximate accuracy to the standard finite element method on the rectangular mesh, while the former has less computational cost and can retain the maximum principle under certain conditions. Moreover, the partitioning conditions for retaining the maximum principle on rectangular mesh are given. References | Related Articles | Metrics

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Thermodynamic properties of ising metamagnet under action of both transverse and longitudinal magnetic fields Liu, Jing (1); Wei, Guo-Zhu (1); Du, An (1) 2008, 29 (8):  1209-1212.  DOI: - Abstract ( 239 )   HTML   PDF (1158KB) ( 618 )   The thermodynamic properties of the two-sublattice Ising metamagnet under the action of both transverse field Ω and the longitudinal field h are studied with the mean-field theory. When the parameter α, i.e., the intensity ratio of interlayer spin coupling to intralayer one, is equal to zero, the internal energy, heat capacity, longitudinal staggered magnetization, longitudinal total magnetization and transverse total magnetization are all calculated to reveal how the internal energy and heat capacity change with temperature. The transverse field Ω enables the internal energy and heat capacity in the system to decrease, thus affecting the thermodynamic properties of Ising metamagnet greatly. References | Related Articles | Metrics

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Effects of shear rate and Ca2+ on conformational transition in regenerated silk fibroin solution Xu, Xiao-Xu (1); Zhang, Bao-Yan (1) 2008, 29 (8):  1213-1216.  DOI: - Abstract ( 248 )   HTML   PDF (345KB) ( 873 )   Polarized light microscopy and Raman spectroscopy were used to study the effects of shear rate and Ca2+ ions on the conformational transition of the aqueous solution of regenerated silk fibroin. The results showed that the shear rate and Ca2+ ions are really the two main influencing factors. For the same regenerated solution, the higher the shear rate, the more the silk fibroin molecules in orderly arrangement along shear rate in the solution. Then, the solution is easier to be transferred to β-pleating conformation from irregular coil or α-helix one, and such a transition is strengthened with increasing shear rate. After dialysis the Ca2+ ion concentration in the solution increases, and the critical shear rate with which the polarized light is visible decreases to a certain extent. And the Raman spectra revealed that the molecular conformation of the silk fibroin is transferred to Silk II from Silk I. References | Related Articles | Metrics