Loading...

Table of Content

    25 July 2009, Volume 37 Issue 7
    Traffic & Transportation Engineering
    Wen Hui-ying Li Jun-hui Zhou Wei-ming
    2009, 37(7):  1-5. 
    Asbtract ( 691 )   PDF (346KB) ( 1138 )  
    Related Articles | Metrics

    The routing planning vital to vehicle navigation system is an important module of the navigation system for delivery vehicles. This paper deals with the routing planning of the delivery vehicle navigation in logistics, and proposes an improved particle swarm optimization algorithm suitable for the point-to-point model of vehicle routing planning. The proposed algorithm improves the fundamental particle swarm optimization algorithm in terms of initial population generation and population evolution strategy. Simulated results confirm the effectiveness and fast computing capability of the proposed algorithm.

    Lu Kai Xu Jian-min Li Yi-shun
    2009, 37(7):  6-9,20. 
    Asbtract ( 652 )   PDF (332KB) ( 1296 )  
    Related Articles | Metrics

    In this paper, first, by using the quantitative analysis method for correlation degree between neighboring intersections, some calculation formulas are put forward to calculate the correlation degree of neighboring intersections and the combinatorial correlation degree of multi-intersections. Next, by defining the solution space, the constraint conditions and the evaluation criteria of the division scheme, a division model of coordinated control subareas is established. Then, by using the layer diffusion algorithm, the subarea division scheme is analyzed and evalua- ted, and the whole division process is given. Finally, an example is presented to discuss the division method of coordinated control subareas based on correlation degree analysis.

    Situ Bing-qiang Jin Wen-zhou Hu Yu-cong Wang Xuan
    2009, 37(7):  10-14. 
    Asbtract ( 539 )   PDF (347KB) ( 748 )  
    Related Articles | Metrics

    The location of passageway of underground roads relates to the linkage between the traffic flows underground and aground. In this paper, first, the combination mode of entrance and exit locations is analyzed, and a minimum-distance model of weaving sections is established, with the lane-changing times as the main judgement criterion. Then, the way to find the maximum key times and the key flow for continuous lane change is illustrated. Finally, according to the characteristics of mixed traffic flow, the discrete threshold value of the minimum distance of weaving sections is obtained via the programming calculation with Matlab. The proposed method supplies refe- rences to the determination of minimum distance between the intersection and the passageway of underground roads.

    Wang Xiao-fei Guo Zhong-yin
    2009, 37(7):  15-20. 
    Asbtract ( 580 )   PDF (414KB) ( 806 )  
    Related Articles | Metrics

    The operation safety of freeway is the basic prerequisite to the high-efficiency operation. This paper puts forward the concept of real-time safety reliability (RTSR) to characterize the operation safety of management units (MUs) of freeway network. In the investigation, first, the division method of management units is proposed. Next, the RTSR of MUs of freeway network is divided into a static safety reliability and a dynamic one, which are then determined by the fuzzy comprehensive judgment and by the reliability graph analysis based on single-vehicle driving risk, respectively. Finally, an example is presented to expatiate the calculation course of RTSR.

    Han Shang-yu Li Hong Hong Bao-ning
    2009, 37(7):  21-25. 
    Asbtract ( 646 )   PDF (357KB) ( 751 )  
    Related Articles | Metrics

    In order to remedy the shortcoming of the traditional decision-making method for prevention measures of risk event unconventionality, a decision-making model based on risk benefit theory is established with the help of Dempster-shafer theory. In this model, similar prophase projects information and risk events are statistically analyzed, and the remedy probability and cost for different decisions are determined. Then, according to decisionmaker's risk preference, the comprehensive probability of latter unconventionality of risk events is determined. Moreover, the risk benefits of different measures are compared, and an optimal decision with maximum benefit is obtained, the reliability of which is evaluated by means of sensitivity analysis. The process and feasibility of the proposed model is finally demonstrated by the example of reducing latter settlement in Foshan First-Ring Road.

    Li Hong-ping Pei Yu-long
    2009, 37(7):  26-30,41. 
    Asbtract ( 800 )   PDF (417KB) ( 1315 )  
    Related Articles | Metrics

    The evaluation of service level of expressway network system is a multi-objective comprehensive evaluation problem. In this paper, by taking the supervisors of expressway system as the appraiser and the expressway system as the objective, a two-level comprehensive evaluation model for service level evaluation is established based on the analytic hierarchy process (AHP) and the fuzzy comprehensive evaluation (FCE) method. Then, the evaluation indices are determined and the weights of the indices are obtained by means of the single-rule AHP method. Moreover, the membership functions of the indices are developed, a suitable fuzzy evaluation model is selected, and a method to determine the evaluation results according to the evaluation aims is put forward. An numerical example indicates that the proposed method is suitable for the evaluation of service level of expressway system in operation.

    Huang Xiao-ming Li Han-guang Zhang Yu-qing
    2009, 37(7):  31-36. 
    Asbtract ( 841 )   PDF (414KB) ( 1432 )  
    Related Articles | Metrics

    Micromechanics theory was employed to investigate the effect of coarse aggregates and air voids on asphalt mixtures’ viscoelasticity. First, Mori-Tanaka’s equivalent inclusion method was used for coarse aggregates and air voids respectively to solve the hybrid inclusions problems of asphalt mixtures in Laplace space. Then the viscoelastic constitutive In order to reveal the effects of coarse aggregates and voids on the viscoelasticity of asphalt mixtures, the hybrid inclusion problem of asphalt mixtures in Laplace space is solved by using Mori-Tanaka's equivalent inclusion method. Then, based on the macroscopic mean field theory, the viscoelasticity of asphalt mixtures is discussed according to that of asphalt mortar matrix. Moreover, by taking the predictions under uniaxial and simple-shear stresses for example, the influences of coarse aggregates and voids on the performances of asphalt mixtures are investigated. The results show that the viscoelastic constitutive equation of asphalt mixtures can be expressed as the product of a comprehensive influence coefficient of coarse aggregates and voids and the viscoelastic constitutive equation of asphalt matrix, that the increase of air voids may result in the decrease of viscoelasticity, while the volumetric fraction of coarse aggregates has an opposite effect, that the weakening effect of air voids is slighter than the strengthening effect of coarse aggregates, that coarse aggregates and voids result in a comprehensive enhancing coefficient of stiffness for asphalt mortar, that the enhancing coefficient under simple-shear stress is approximately 2 times that under uniaxial stress, and that Poisson's ratio of asphalt mortar matrix can be regarded as a constant in the following researches due to its slight effect on the comprehensive influence coefficient.

    Wang Duan-yi Zhao Xi
    2009, 37(7):  37-41. 
    Asbtract ( 2678 )   PDF (349KB) ( 1548 )  
    Related Articles | Metrics

    :To ease the limitation of continuous medium theory, a uniaxial compression test of asphalt mixture is simulated with the discrete element method (DEM) , and the constitutive behaviors of the mixture accordant with practical results are investigated. Moreover, the effects of micro-parameters of DEM sample on the constitutive behaviors are discussed. The results indicate that, when other parameters remain constant, the peak strength of the sample increases with the contact stiffness and the contact bond strength at relatively low strain and high axial strain, respectively, that large friction coefficient may result in high peak strength, and that the peak strength increases with the parallel bond radius and the softening phenomenon of the stressstrain curve becomes more marked.

    Ge Zhe-sheng Zhang Xiao-ning Yu Jiang-miao
    2009, 37(7):  42-45. 
    Asbtract ( 660 )   PDF (274KB) ( 907 )  
    Related Articles | Metrics

    In order to remedy the shortcomings of the measurement of voids in coarse aggregates (VCAs) in dryrodded condition, the concept of minimum VCA and the corresponding mensuration are put forward. Then, the gradation intervention coefficient of asphalt mixture and a new standard of coarse aggregate contact are defined, according to which the existing "Coarse Aggregate Void Filling (CAVF)" method is improved. Moreover, the relationship between the gradation intervention coefficient and the asphalt mixture properties such as the high-temperature rutting resistance and the fatigue resistance is analyzed. The results show that the proposed standard of coarse aggregate contact based on the minimum VCA accurately determines the contact degree of coarse aggregates, that the improved CAVF method helps to design dense gap-graded mixtures satisfying the requirements of existing criteria, and that there is good correlation between the gradation intervention coefficient and the high-temperature rutting resistance as well as the fatigue resistance of the mixture.

    Dong Ze-jiao Liu Hao Tan Yi-qiu Chert Feng-chen Wang Bao-xin
    2009, 37(7):  46-51. 
    Asbtract ( 737 )   PDF (420KB) ( 999 )  
    Related Articles | Metrics

    The measurement of dynamic strain of asphalt pavement helps to effectively reveal the real mechanical state within the pavement structure. In this paper, a three-direction strain measurement method at a single testing point, which is different from the traditional unilateral measurement at a single point, is proposed. Then, the in-situ layout scheme for Fiber Bragg Grating (FBG) strain sensors is presented, and the measured three-direction dyna- mic strain in different loading conditions are compared and analyzed. The results show that the three-direction strain measurement provides more useful information about the observable viscoelastic characteristics of asphalt pavement, and that the strain response of pavement varying with loading conditions basically decreases with the increase of vehicle speed. Some suggestions for the field strain measurement and its further development are finally offered in this paper.

    Wan Cheng Zhang Xiao-ning Yu Jiang-miao
    2009, 37(7):  52-56. 
    Asbtract ( 584 )   PDF (399KB) ( 923 )  
    Related Articles | Metrics

    At present, the indirect tensile method (splitting test) is commonly used in China to test the fatigue performanee of samples. However, there exist obvious differences between the loading mode of the method and the actual stress state of pavement, and the actual cracking mode is often inconsistent with the theoretical cracking location. In order to solve these problems, a four-point bending fatigue test system Cooper NU-14 was used to evaluate the fatigue performance of asphalt mixtures. The whole process of the test, including the experimental facility, the specimen fabrication, the experimental parameter setting and the loading, was described in detail, and the fatigue performances of the mixtures with different asphalt types and stone matrix asphalt were tested and quantitatively compared. The results show that the testing system effectively evaluates the fatigue performance of inhomogeneous asphalt mixtures, and that both the properties of the binder and the aggregate gradation significantly influence the fatigue performance of asphalt mixtures

    Automotive Engineering
    Du Qun-gui Liu Qiu-cheng Xue Yun-feng Zou Jie-hui
    2009, 37(7):  57-61,68. 
    Asbtract ( 563 )   PDF (430KB) ( 1523 )  
    Related Articles | Metrics

    In this paper, first, a new type of vehicle safety belt is developed based on a new clutch proposed as the key part of pretensioner of safety belt. Next, the structure composition, working principle and performances of the belt are introduced. Then, a mechanical model of the belt is established and the dynamic simulation and performance analysis for the pretensioner are carried out with ADAMS, finding that the new clutch is capable of transmitting movements credibly with an appropriate unreeled belt length. Finally, a frontal impact model of the belt is established with MADYMO. Simulated results show that the parameters, such as the head injury criterion, the thoracic acceleration, the axial femur force and the chest deformation, all reach the relevant standards such as GB11551-2003 and ECER94 well, that other injury indexes, such as the viscous injury response, the combined thoracic index and the cumulative 3-ms thoracic injury criterion, are all small enough for safety, and that the regu- larized injury index is kept at about 0.48. It is thus concluded that the newly-designed clutch effectively reduces the injury to passengers and furnishes passengers good protection.

    Wang Feng Zhong Hu Ma Zi-lin Mao Xiao-jian Zhuo Bin
    2009, 37(7):  62-68. 
    Asbtract ( 880 )   PDF (419KB) ( 1049 )  
    Related Articles | Metrics

    This paper deals with the emulated engine compression braking (EECB) of parallel hybrid electric system. When the vehicle is in a coasting mode, the electric clutch is disengaged, and the electric motor (EM) provides negative torque to emulate the engine drag torque for charging the battery, thus making full use of the coasting energy. Then, by taking into account the EM generation efficiency and the battery charging efficiency, an EM torque optimization (ETO) control algorithm is proposed to maximize the actual electric power recuperated by the battery and to obtain the optimal EM torque and the corresponding optimal shift-control rule of the automatic me- chanical transmission. Simulated results indicate that the EECB with ETO offers a greatly improved battery state of charge.

    Tong Wei Guo Kong-hui Huang Xiang-dong
    2009, 37(7):  69-73. 
    Asbtract ( 551 )   PDF (281KB) ( 1112 )  
    Related Articles | Metrics

    A vehicle body may bear a large twist load due to the uneven load on four wheels when the vehicle runs on rough road. In order to reduce the twist load, a new type of torsion-eliminated suspension structure is brought forward, and a simple mathematical model is established to explain the principle of torsion elimination. Moreover, a model of the vehicle with the suspension is constructed by using the multi-body dynamics simulation software ADAMS, and the abilities of torsion elimination and ground adhesion of the vehicle at various speeds are simulated. The results show that, when the vehicle runs at a low speed, the torsion-eliminated suspension is effective in reducing the twist load of vehicle body and in improving the ability of ground adhesion.

    Luo Yu-tao Tan Di Liu Yan-wei Zhou Si-jia
    2009, 37(7):  74-78. 
    Asbtract ( 874 )   PDF (344KB) ( 875 )  
    Related Articles | Metrics

    In this paper, a steering forecasting model of four-wheel-driving electric vehicle is established based on the expanded EIman network, and a nonlinear adaptive forecasting controller of the network is put forward by means of system identification. Moreover, by feeding back the distribution proportion of longitudinal force, the control method of vehicle stability with the aid of driving force distribution between axles is investigated. Simulated and analytical results indicate that the proposed method with good predictive control ability achieves smooth control and rapid target tracking, so that it effectively improves the lateral dynamic stability of vehicles, and helps the driver to modify the steering characteristics of the vehicles in most conditions.

    Xue Yun-feng Du Qun-gui Zhu Jun-peng
    2009, 37(7):  79-84. 
    Asbtract ( 598 )   PDF (393KB) ( 1299 )  
    Related Articles | Metrics

    The working principle and structural design of a new hypocycloid energy transformation mechanism is in- troduced, and the dynamic model of the mechanism is established using the Euler-Lagrange approach based on energy. Afterwards, a numerical simulation based on four-order Runge-Kutta's method is performed with Matlab. The results show that the simple-harmonic rectilinear motion of piston in the new mechanism makes the engine work more stably, that the peak acceleration in the new mechanism is 25 % less than that in the conventional slider-crank mechanism, and that the output rotational speed of the new mechanism is much higher at the same mean equivalent cylinder pressure and load torque, thus improving the output power of the engine.

    Yang Rong-shan Huang Xiang-dong Yuan Zhong-rong Zhao Ke-gang
    2009, 37(7):  85-89. 
    Asbtract ( 940 )   PDF (331KB) ( 1778 )  
    Related Articles | Metrics

    Based on the theory of multi-body system dynamics, the front McPherson suspension of a car is modeled with the dynamics software of mechanical systems, and the structure of the suspension is optimized with genetic algorithm in a multi-objective/multi-parameter optimization environment, which results in an optimal layout of the suspension hardpoints under the engineering constraint conditions for improving the suspension performance. Test results of the optimized suspension on a test rig show that the optimization is correct, and that the proposed muhiobjective/multi-parameter optimization method is effective in improving the suspension performance of a vehicle.

    Yu Xue-hua
    2009, 37(7):  90-93,105. 
    Asbtract ( 944 )   PDF (288KB) ( 1068 )  
    Related Articles | Metrics

    The acoustic-cavity resonance inside the tire-wheel assembly may results in the interior noise of running vehicles. In order to solve this problem, the characters of noise caused by acoustic-cavity resonance are analyzed, and the motion equation of the acoustic cavity system is deduced. Moreover, an improvement technique is proposed to reduce the peak level of the acoustic-cavity natural frequency by modifying the wheel with an elliptical rim. The correctness of the proposed method is finally validated by experiments.

    Power & Electrical Engineering
    Wang Xiao-gang Xie Yun-xiang Shuai Ding-xin Huang Shao-hui
    2009, 37(7):  94-99. 
    Asbtract ( 716 )   PDF (381KB) ( 2065 )  
    Related Articles | Metrics

    Proposed in this paper is a novel fast three-dimension space-vector pulse-width modulation (3D-SVPWM) algorithm for controlling the four-leg voltage source inverter. In this algorithm, the tetrahedron and action duration of the vector are directly determined by using three-phase reference voltages with simple calculation, thus remedying the shortcomings of complex calculation and large time cost of the conventional algorithm with coordinate transformation. The relationships between the proposed algorithm and three other modulation methods, including the time-domain control equation solution, the sinusoidal pulse-width modulation and the 2D-SVPWM of four-leg inverter, are analyzed, with an uniform action duration model of vector being also found. Moreover, the voltage utilization ratio of the inverter with 3D-SVPWM is analyzed, and the simulated results of the four-leg inverter with the four above-mentioned methods are compared. It is found that the proposed algorithm is correct and effective, and that the four above-mentioned methods are equivalent.

    Wang Tong-wen Guan Lin Zhang Yao
    2009, 37(7):  100-105. 
    Asbtract ( 511 )   PDF (412KB) ( 927 )  
    Related Articles | Metrics

    A modified knowledge discovery algorithm is proposed in this paper. In view of the limitations of the original pattern discovery algorithm based on residual analysis and recursive partitioning, different discretization criteria are adopted during the partitioning of sample space because different attributes have different contributions to pattern discovery. The proposed algorithm automatically adjusts the pattern-classifying criterion according to the subspace number. The application results on synthetic data set and power system stability assessment show that the proposed algorithm is rational and effective, and that it is of higher knowledge discovery efficiency and wider application, as compared with the original algorithm.

    Xie Min Zhong Jin
    2009, 37(7):  106-111. 
    Asbtract ( 531 )   PDF (447KB) ( 974 )  
    Related Articles | Metrics

    The ordinal optimization theory based on practical engineering provides an efficient tool to obtain good enough solutions to transmission expansion planning problem with a high probability, and helps to remarkably lighten the computation load and well satisfy the engineering requirements. In this paper, the ordinal optimization theory is employed to seek good enough planning schemes for transmission expansion, with the sum of the expansion investment cost to transmission owners, the generation cost to generators and the possible outage cost to customers as the objective function. Test results in a Garver system show that the transmission expansion planning based on the ordinal optimization theory is effective and feasible in practice.

    Xiao Jian Wen Fu-shuan
    2009, 37(7):  112-118. 
    Asbtract ( 557 )   PDF (464KB) ( 890 )  
    Related Articles | Metrics

    In the existing hybrid electricity markets, the pool and the bilateral-contract trades commonly interfere with each other. In order to effectively coordinate and dispatch these two trade modes, a coordinated congestiondispatching model for pool-bilateral markets by introducing a coordinated constraint to deal with the priority of the two trades. In this model, the curtailed generation of contracts is allowed to re-dispatch in the pool market, thus decreasing the purchasing cost of pool trade. Case study indicates that the proposed model is effective.

    Lu Ji-dong Wang Ling-ling Lu Zhi-min Yi Xin-jian
    2009, 37(7):  119-122. 
    Asbtract ( 513 )   PDF (272KB) ( 1398 )  
    Related Articles | Metrics

    Indonesia coal is one of the important burning coal for thermal power plants in China coastal region. It is often blended with other coal for burning. In this paper, a thermogravimetric analysis was performed to investigate the burning process of Indonesia coal blended with other three kinds of bituminous coal at different blending ratios, and the activation energies of these kinds of blended coal were compared to reveal the corresponding ignition characte- ristics. Experimental results indicate that Indonesia coal is easy to ignite due to its low activation energy and may improve the ignition characteristics of the blended bituminous coal with poor ignition characteristic, and that, when it blended with other coal with similar ignition characteristics, the ignition characteristic is similar to that of the coal with low activation energy.

    Lou Bo Luo Yu-he Ma Xiao-qian
    2009, 37(7):  123-126,131. 
    Asbtract ( 579 )   PDF (308KB) ( 815 )  
    Related Articles | Metrics

    The mean residence time (MRT) of materials in a rotary kiln directly affects the extent of chemical reaction. In this paper, the variation rules of MRT for different kinds of solid wastes were experimentally investigated at various air velocities in kiln, rotational speeds of kiln, inclination angles of kiln and physical properties of raw materials. The results indicate that MRT decreases with the increase of rotational speed, inclination angle, air velocity and repose angle, that the repose angle of the material greatly affects MRT, which is different from the density, and that, with the increase of air velocity, MRT first greatly decreases then keeps unchanged. A MRT model considering air velocity (MMCAV) is finally established and validated at a certain air velocity, with an average relative error of 7.69% between MMCAV and experimental data being obtained.

    Li Min-yi Yang Ze-liang Wu Sheng-ju
    2009, 37(7):  127-131. 
    Asbtract ( 709 )   PDF (338KB) ( 814 )  
    Related Articles | Metrics

    According to the expression of ultrasonic power based on the series resonant equivalent circuits, a method to measure the radiation conductance of standard ultrasonic transducer with a 4192A impedance analyzer is presented. The radiation conductance measured by the electrical method is then compared with that obtained by the national primary standard equipment for milliwatt ultrasonic power based on the radiation pressure method. The results indicate that the errors of radiation conductance of quartz-crystal, standard transducers with the nominal frequencies of 2. 5 and 5.0 MHz are respectively kept at 0. 35% and 2. 11% , that the en'or of uhrasonie power of transducers is not greater than 3% when the error of voltmeter is not greater than 1%. Moreover, it is found from experimental results that the proposed method with simplicity and reliability can not only test the standard transducers whose ultrasonic powers are measured by means of the radiation pressure method but also act as a new measurement standard.

    Physics
    Liu Xue-mei Wen De-hua Xie Hui-zhang Gao Ya-ni
    2009, 37(7):  132-134. 
    Asbtract ( 518 )   PDF (191KB) ( 808 )  
    Related Articles | Metrics

    More and more biological experiments and is a nonlinearly stochastic process, in which the noise theoretical simulations have re,revealed that the gene expression can not be ignored. In this paper, additive and multiplicative noises are introduced in the kinetic model of activator proposed by Smolen for gene transcription regulation, and the corresponding Langevin and Fokker-Planck equations are solved to analyze the steady-state probability distribution theoretically and numerically. It is found that multiplicative noise significantly affects the steady-state probability distribution and converts the hi-stability to the monostabillity, and that additive noise helps to reduce the transcription efficiency.

    Zhou Xiao-ming
    2009, 37(7):  135-137,146. 
    Asbtract ( 545 )   PDF (260KB) ( 881 )  
    Related Articles | Metrics

    In order to investigate the radioprotective role of left-handed materials-split ring resonators ( SRRs)in reducing the electromagnetic radiation from a cellular phone, a numerical simulation model of the interaction system between cellular phone with SRRs and human body is established, and the specific absorption rate (SAR) of radiation dosage in human body is calculated by means of finite-difference time-domain (FDTD) method. Moreover, the influence of SRRs on the communication quality of cellular phone is analyzed by using antenna radiation patterns. The results indicate that, by using SRRs, the average SAR peak values per 1 g and 10g human tissues decrease by more than 50%, and the radiation intensity decreases by less than 10dB. It is thus concluded that SRRs markedly reduce the harm to human body caused by cellular phone radiation, and its influence on communication quality keeps in an acceptable range.

    Mathematics
    Ma Dong-kui Hu Chao-jie
    2009, 37(7):  138-141. 
    Asbtract ( 565 )   PDF (271KB) ( 850 )  
    Related Articles | Metrics

    :In this paper, by supposing E to be the attractor of an iterated function system (X,f1,…,fN) which satisfies the strong separation condition, defining a continuous mapping f: E→Ef(x) =f -1j (x), x x∈fj(E), j = 1,..., N, and setting (p1 ,P2,…,PN) as a probability vector andμ the corresponding invariant measure, some complex dynamical behaviors of the continuous mapping are investigated. The results indicate that, for the mappingf, there exists a finitely chaotic set C CE satisfyingμ(C) =μ(E) = 1, and that the mapping f has some chaotic minimal subsystem with zero topological entropy in the sense of Li-Yorke. Some existing results are tinally generalized in the paper.

    Zhang Yi-min Shen Yao-tian
    2009, 37(7):  142-146. 
    Asbtract ( 597 )   PDF (213KB) ( 749 )  
    Related Articles | Metrics

    This paper deals with a class of nonlinear biharmonic problem with critical potential and indefinite potential in R4. In the investigation, the exponent in critical potential is proved optimal, and the existence of the nontrivial solution is proved by using an optimal Hardy inequality and the character of the first eigenvalue.

News
 
Featured Article
Most Read
Most Download
Most Cited