西南交通大学学报

Research on Transport Operation Mode of Wuhan-Guangzhou Passenger Special Line

PENG Qi-yuan, YANHai-feng, WEI De-yong

2004, 17(6): 703-708.

[Abstract](1380)

Abstract:
By combining quantitative calculation and qualitative analysis, the transport operation mode and its feasibility, and the off-line train running scheme of Wuhan-Guangzhou passenger special line were investigated. The research shows that a multi-speed transport mode should be adopted in the passenger special line. In this mode, off-line and in-line trains share the same line, and the combined traction way of a motor train unit and an ordinary locomotive is used for off-line trains.

Influence of Vertical Skylight on Carrying Capacity of Railway Lines

YIN Yong, YANHai-feng, ZHOU Yong

2004, 17(6): 708-711.

[Abstract](1592)

Abstract:
Based on the analysis of the structure of train diagrams, freight train painting schemes in influencing timeslice before and after a vertical skylight were discussed, a mathematics model was proposed for the deduction of carrying capacity of railway lines resulted from vertical skylights. The analysis of this model shows that the deduction of carrying capacity of a railway line is directly proportional to the time span of vertical skylights and inversely proportional to the interval between freight trains.

Generation of Turbulent Kinetic Energy and Severe Clear Air Turbulence in Flight

WANG Yong-zhong

2004, 17(6): 712-715.

[Abstract](1405)

Abstract:
Based on the tendency equation of turbulent kinetic energy, its simplified equation including only wind shear and air stability was derived. In addition, this simplified equation was tested using the environmental technical application (ETA) mode and the data of 100 cases of clear air turbulence (CAT) in flight. The research shows that the prediction of CAT in flight should not be based on only the generation of turbulent kinetic energy, and it is necessary to diagnose the generation item for turbulent kinetic energy. The dissipation item in the tendency equation of turbulent kinetic energy can not be neglected in the prediction of CAT, and the vertical divisional rate of the ETA mode and the air stability given by the mode designer have also an effect on the precision of CAT prediction.

Optimal Model of Daily Freight Plan of Railway Sub-administration Dispatch Based on Benefit Mechanism

ZHOU Yong, PENG Qi-yuan, LI Shi

2004, 17(6): 716-720.

[Abstract](1521)

Abstract:
In order to get the maximum transportation benefit under the limited traffic resources, an optimal model of daily freight plans of railway sub-administration dispatch was established based on the benefit mechanism and the exact mathematics descriptions of traffic restrictions such as capability of stations, supply of empty vehicles, capability of limited nodes and capacity of dividing stations. In this optimal model, the object function is to get the maximum transportation benefit, and the constraint conditions are the traffic restrictions.

Research of Value Evaluation Method for Growth Enterprises

TU Qiao-ping, HUPei, WEI Ya-qing

2004, 17(6): 720-724.

[Abstract](1294)

Abstract:
The evaluation methods for growth enterprises were investigated respectively from the angles of certain investment and uncertain investment. An evaluation model characterizing the growth features of different stages was put forward through analyzing the shortcomings of one-step growth evaluation models. From the characteristic of managerial flexibility of growth enterprises, the real option pricing approach was adopted to evaluate the value of managerial flexibility with single growth chance or sequential growth chance, which overcomes the inherent faults of the discounted cash flow method in evaluating the value of managerial flexibility.

Prediction and Analysis of Environmental Kuznets Curve Based on Fuzzy Neural Network

CHUHai-lin, LIJun

2004, 17(6): 725-729.

[Abstract](1385)

Abstract:
To provide a basis for regional economics decision-making, based on the theory of fuzzy neural networks (FNN) an environmental Kuznets curve (EKC) was investigated quantitatively by predicting the coordination degree of environment and economic development. As an example, the coordination degree of environment and economic development of Chengdu City, Sichuan Province, was predicted, and based on the predicted result, the relationship between the environment and economic development of Chengdu City was analyzed. The analysis shows that there is not a marked peak value on its environmental Kuznets curve,i.e.,the relationship between its environment and economic development tends towards coordination.

Computation of Flexural Rigidity of Steel Reinforced Concrete Beam

ZHAO Shi-chun, SHIJian-ping

2004, 17(6): 730-733.

[Abstract](1373)

Abstract:
Based on the assumptions that a plane section before bending remains a plane after bending and no relative movement takes place between steel and concrete, an expression for the flexural rigidity of steel reinforced concrete (SRC) beams as a function of the rigidities of steel and concrete was derived. The approximate and simplified formulas for calculating the flexural rigidity of SRC beams were proposed based on the expression, the relevant formulas given in the Chinese current design codes for concrete structures, the approximate position of neutral axis and the approximate stress factor of the reinforcement including the tensile flange of steel. The proposed formulas agree well with experimental results and may be used as a reference for structural engineers.

Research on Free Vibration Properties of Membrane Structure

YUZhi-xiang, ZHAO Lei

2004, 17(6): 734-739.

[Abstract](1220)

Abstract:
By taking two typical tensile membrane structures as examples, the free vibration properties of membrane structures were investigated using the Block Lanczos method, and the effects of stiffness of strengthened cables, prestress on membrane, ratio of rise to span and mass of membrane were discussed. The results show that the prestress and the mass are the two most important factors influencing the free vibration properties, and the geometry update resulted from large deformation has also a great effect on the free vibration properties. Finally, the concept of mode analysis considering the geometry update was put forward based on the effect of nonlinear large deformation on geometric stiffness of membrane structures.

Identification of Static Coefficients of Bridge Section with Artificial Neural Network

LI Lin, LI Qiao, LIAO Hai-li

2004, 17(6): 740-744.

[Abstract](1982)

Abstract:
Based on enough samples obtained by model experiments in wind tunnel, two BP artificial neural networks (ANNs) were constructed with the MATLAB toolbox of ANN. Then the two ANNs were used to train static coefficients in two different coordinate systems.i.e.body and wind coordinate systems, and training results of static coefficients of bridge section in the two coordinate systems were compared using the Bayesian regularization algorithm. The result shows that a four-layer network is more efficient and has better accuracy. Finally, some problems to the application of ANNs to the identification were pointed out.

Numerical Simulation of Segment Joint Bending Stiffness of Metro Shield Tunnel

ZENG Dong-yang, HE Chuan

2004, 17(6): 744-748.

[Abstract](1626)

Abstract:
The numerical simulation of segment joints of Nanjing metro shield tunnel was carried out with 3D FEM (finite element method). The deformation, rotational angle and bending stiffness of a segment joint under different working conditions were investigated, and the varying law of rotational angle and bending stiffness were discussed. In addition, the fitting relation between rotational angle of a segment joint and bending moment and axial force was obtained to provide a new way of determining joint bending stiffness. The numerical result shows that the bending stiffness of segment joints increases with the increasing of axial force, and the bending stiffness decreases rapidly and trends unchanged with bending moment increasing. Influence of axial force on joint bending stiffness weakens with the increasing of bending moment.

Compressional Creep Test of High Embankment Settlement

LIUHong, LI Pan-feng, ZHANG Zhuo-yuan

2004, 17(6): 749-753.

[Abstract](1232)

Abstract:
By taking the embankment, with a height of 104 m, of Jiuzhai-Huanglong airport as an example, similar conditions of compressional creep tests simulating the high embankment using filling material of sandy gravel were investigated. The research results show that the compressional creep tests with rigid boundary conditions have favorable similarity with the large-scale high embankment in a depression, and their stress states are very close to the same, but the amount of settlement obtained from the compressional creep tests with rigid boundary conditions are less than that of in-situ monitoring. Furthermore, the degree of initial compaction of the coarse grain filling material controls its compressional characteristics. When the degree of initial compaction is 97.4%, the process of compaction settlement shows a logarithmic characteristic, and when the degree of initial compactio is above 98. 7%, the process of compaction settlement indicates a linear characteristic.

Rough Set Algebra and Lattice Implication Algebra

QIN Ke-yun, TU Wen-biao

2004, 17(6): 754-757.

[Abstract](1272)

Abstract:
The relation between rough set algebra and lattice implication algebra was studied, and the method of constructing lattice implication algebra from rough set algebra was presented. Based on the atoms and congruence relations of approximation algebra, it is proved that rough set algebra becomes lattice implication algebra if proper implication and complement operators are selected.

Smoothness of the Global Weak Solutions for a Kind of Nonlinear Fourth Order Wave Equations

CHEN Yong-ming, XIEHai-ying, YANG Han

2004, 17(6): 758-760.

[Abstract](980)

Abstract:
The initial boundary value problem of a kind of nonlinear fourth-order wave equations describing beam vibrations was studied. With Galerkin method, it is proved that the smoothness of the global weak solution can be improved if the smoothness of the initial value is improved. By virtue of Sobolev s embedding theorem, the global weak solutions become classic ones when the initial value is appropriately smooth.

Homoclinic Orbits for a Singular Second Order Planar Hamiltonian System

YANG Shou-jian

2004, 17(6): 761-763.

[Abstract](1269)

Abstract:
The existence of a homoclinic orbit for a singular second order planarHamiltonian system is proved by using variational methods. The main assumptions are the strong force condition and the uniqueness of a global maximum of a singular potential. The functional corresponding to the approximate problem satisfies the Palais-Smale compactness condition and attains its infimum. Solutions of this approximate problem are obtained as minimal points of the fanctional. The homoclinic orbit is the limit of these solutions.

Distributed Security Auditing System Based on BAS

GOUXian-tai, JIN Wei-dong

2004, 17(6): 764-767.

[Abstract](1411)

Abstract:
A broadband access server (BAS) was used as auditing agent to implement a distributed security auditing system on metropolitan area network (DSASMAN). A new packet filter mechanism based on hardware packet filter (HPF) was proposed. The mechanism of routing and forwarding in BAS was modified from“route once, switch many”to“audit once, pass many”. The algorithm based on time inductive machine was used to accomplish the auditing to UDP based accesses. The proposed auditing system has been implemented in an experimental routing switch that was used as a BAS and showed good auditing performances.

Performance Analysis of Multi-code CDMA ALOHA System

PAN Su, LIU Shu-guang, QIU Bo

2004, 17(6): 768-771.

[Abstract](1242)

Abstract:
Based on the multi-code CDMA (code division multiple access) and ALOHA techniques, a multi-code CDMA ALOHA system to support multi-rate data services was proposed. The throughput performance of the proposed system under an additive white Gaussian noise (AWGN) channel was analyzed and simulated. The results show that the proposed system can support multi- rate data traffics and has a satisfactory throughput performance because of combining the advantages of multi-code CDMA and ALOHA protocol.

Adaptive Error Concealment Algorithm Based on H.26L

LIUHai-bo, PENG Qiang

2004, 17(6): 772-775.

[Abstract](1119)

Abstract:
An adaptive error concealment algorithm based on H.26L was proposed by making use of the feature and parameters of decoded frames. The algorithm uses three concealment algorithms, namely, boundary matching algorithm (BMA), spatial interpolation ( SI) and frequency interpolation (FI), adaptively according to error characteristics. It is independent of information provided by the encoder. Simulation results showed that the proposed algorithm was much more effective subjectively and objectively than any of the existing ones, especially for the changing scenes and fast motions.

Quasi-synchronous Scheme for Frequency Hopping System Based on No-Hit-Zone Hopping Code

FENG Li-fang, WANG Xiao-ning, YE Wen-xia, PENG Dai-yuan

2004, 17(6): 776-779.

[Abstract](1264)

Abstract:
According to the characteristics of No-Hit-Zone (NHZ) hopping code, a multi-access quasi-synchronous scheme based on NHZ hopping code for frequency hopping communication system was proposed. Simulation results prove that the scheme assured the frequency hopping system to work within NHZ hopping code. It decreases the multi-access interference and improves the integral bit error rate performance of the system, and is suitable for multi-user frequency hopping system.

Construction of Complete Combinatorial Keyboard Circuit

JIN Wei, XIAO Bo, WUZhi-quan

2004, 17(6): 780-783.

[Abstract](1392)

Abstract:
A new method for constructing keyboard circuit, namely, completely combinatorial keyboard circuit, was proposed. The new key board is composed ofnbidirectional interfaces based on the principle of permutation and combination. It allows the maximum number of 2n-1+n (2n-1- 1) keys to be implemented on thenbidirectional interfaces, much larger than the conventional matrix key board. Its components can also be utilized to construct key board circuits according to practical requirement.

Demodulation of Frequency-Shifting Signals of Automatic Block System with PLL

XIANG Jun

2004, 17(6): 784-787.

[Abstract](1195)

Abstract:
Signal demodulation of automatic block with audio frequency shift modulated track circuits was implemented with phase-locked loop (PLL) technique and a singe chip microcomputer. Experiment showed that the demodulation system can not only reduce the low-frequency pulses from the received signals, but also effectively depress the noises induced in the track circuits and achieve high signal-noise ratio.

Analysis and Application of Dynamic Spectrum of Friction-Induced Noise

GAO Pin-xian, WU Chuan-hui, GAO Xiang-ling

2004, 17(6): 788-791.

[Abstract](1182)

Abstract:
Dynamic spectrum was applied to analysis of friction-induced noises. The result indicates that a dynamic spectrum contains rich information about time-variation, frequency spectrum structure and dynamic range of friction-induced noises. Experiments prove that dynamic spectrum is very sensitive to the change of operating parameters of equipment and can be applied to monitoring and fault diagnosis for equipment under operation. The average gray-scale of dynamic spectrum was selected as a fault sensitivity factor, and their quantification procedures were introduced.

Response Localization of Asymmetrical Plate-type Structure in Still Water

FAN Chen-guang, LU Li, YANG Yi-ren

2004, 17(6): 792-796.

[Abstract](1433)

Abstract:
To study the forced response localization phenomenon of asymmetric plate-type structures in still water, the assumption mode method was used to derive the vibration model. The analysis was focused on the asymmetric length of the structure and low order natural frequencies. The results show that the response localization of the model becomes stronger with an increase in asymmetry of structure when the asymmetry is small, the coupling effects of water on the upper and lower plates are different.

Modeling Uniaxial Saturated Ratcheting Strain for 1Cr18Ni9Ti Stainless Steel

YE Yu-ming, CAI Li-xun

2004, 17(6): 797-801.

[Abstract](1226)

Abstract:
A set of uniaxial ratcheting tests for 1Cr18Ni9Ti stainless steel were carried out at room and elevated temperatures. The effects of peak stress, mean stress, low cyclic stressing histories and temperature on saturated ratcheting (SR) strain were investigated. Based on the parabolic relation between peak stress and SR strain, and the linear relation between ratcheting stress and temperature, the saturated ratcheting evolution models at room and elevated temperatures were presented by using single-specimen method.

New Method for Prediction of High Cycle Fatigue Life

HAO Yu-long, DAI Zhen-yu, HUANG Yu-zhong

2004, 17(6): 801-804.

[Abstract](1438)

Abstract:
Randomly distributed models of micro-plastic strains were used to calculate the micro- plastic deformation produced at each cycle of the steel under high cycle fatigue test. The micro- plastic strains are determined by combining the true fracture ductility of the steel under test. For 40Cr steel, the errors of the fatigue life calculated with the proposed method are less than 30% compared with that determined by test.

Preparation of Nano-scale PEG/Fe3O4Ferrofluids

HU Shu-chun, ZHOUZuo-wan, CHU Long-sheng

2004, 17(6): 805-808.

[Abstract](1330)

Abstract:
Nano-scale ferrofluids of PEG (polyethylene glycol)/Fe3O4were preparedviathe technology for synchronously preparing magnetic particles and covering surfactant and using water as the working fluid and PEG as the surfactant, and the effect of PEG content on the micromorphology and size of PEG/Fe3O4colloidal particles in ferrofluids was investigated. The results indicate that the micromorphology and size of colloidal particles are obviously influenced by PEG content in the reaction system, and products with a shape of sphere or bar can be prepared by changing PEG concentration. A further study shows that there exist the interactions of physical adsorption and hydrogen bonding between Fe3O4particles and PEG.

Aluminum Species and Flocculating Mechanism of Polymeric Aluminum Silicate Sulfate

LIU Ying, ZHANG Dai-jun

2004, 17(6): 809-814.

[Abstract](972)

Abstract:
A series of polyaluminum silicate sulfate (PASiS) with different basicities, Al/Si molar ratios and silicic acid polymerization degrees was prepared by the copolymerization (COPOLY) and composite polymerization (COMPOLY) techniques. The distribution of aluminum species in PASiS, the charged characteristic of its hydrolysis products and their affecting factors were investigated by the Al-Ferron timed complex colorimetric method and the micro-electrophoresis method. In addition, the interaction between polysilicic acid and hydrolysis aluminum species in PASiS was discussed. The experimental results of water treatment show that the flocculation effect of PASiS is better than polyaluminum chloride, polyaluminum sulfate, polyaluminum sulfate- chloride and polyacrylamide, and PASiS (COPOLY) is better than PASiS (COMPOLY). The flocculation properties of PASiS are related to the basicity, Al/Si molar ratio and polymerization degree. The adsorbing-bridging and entrapping-settling are the principal mechanisms of PASiS functioning.

Measure Regulation of the Sakyamuni Pagoda in Yingxian County, Shanxi Province

XIAO Min

2004, 17(6): 815-818.

[Abstract](1104)

Abstract:
By analyzing the measure data of the Sakyamuni pagoda in Yingxian County, Shanxi Province, a new measure regulation was put forward based on the former viewpoints. According to the new measure regulation, the change in the side length of each span of each story can be further explained. The research shows that the measure regulation of this Sakyamuni pagoda is a modulus system, and the basic modulus is 22.1 cm to control the height and the side lengths of each story and each span. Based on the basic modulus, the side lengths of each story and each span have a gradually changing and simple regulation. This phenomenon is similar to that of some ancient pagodas in the periods of Asuka and Nara in Japan and can be used as an important evidence to the existence of a modulus system in ancient buildings in the period from the Tang Dynasty to the Song Dynasty.

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2004 Vol. 17, No. 6