西南交通大学学报

Research Progress in Cyclic Deformation of Super-Elastic NiTi Shape Memory Alloy

KANG Guozheng

2011, 24(3): 355-364. doi: 10.3969/j.issn.0258-2724.2011.03.001

[Abstract](1300)

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Abstract:
The research progresses in cyclic deformation of super-elastic NiTi alloy in the last two decades were reviewed, with an emphasis on the changes in some important mechanical parameters, the evolution of residual strains, and behaviors of transformation ratcheting. Three typical cyclic constitutive models of super-elastic NiTi alloy constructed based on the macroscopic phenomenological constitutive model, as well as their abilities to describe the cyclically accumulated residual strains and transformation ratcheting of the alloy, were outlined. Suggestions about the future work were presented to overcome the shortcomings in the existing researches, such as those in thermo-mechanical coupled cyclic deformation, non-proportional multiaxial cyclic deformation, and micro-mechanism of cyclic deformation.

Mesoscopic Numerical Simulation of Bond Behavior of Ribbed Bars and Concrete

WANG Hailong|LIChaohong|XUGuangxing

2011, 24(3): 365-372. doi: 10.3969/j.issn.0258-2724.2011.03.002

[Abstract](1868)

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Abstract:
In order to research the failure mechanism of bond between ribbed bars and concrete and discuss the influence of rib outline on bond behavior at a meso-level, a 3-D mesoscopic numerical model for reinforced concrete was established with ANSYS parametric design language. This model is based on a mesoscopic model for concrete and considers bars, and elements of each mesoscopic phase are generated by refining interface elements and distinguishing material properties. Two numerical models for pullout specimens for crescent-ribbed bar or screw thread bar were established respectively, and their bond failure processes were simulated. The damage and fracture region of concrete and the stress state of ribs were analyzed. The results show that the bond strength between a crescent-ribbed bar and concrete is slightly lower than that between a screw thread bar and concrete, but the stress concentration in concrete between crescent-ribbed bar's ribs is low and the damage degree is light. The simulated bond stress and bar slippage are approximate to their experimental values to show that the proposed numerical model can be used to research on bond behavior between bars and concrete.

Dynamic Responses of East Temple Pagoda of Subashi Temple under Seismic Loads

CHEN Wenwu, LIPengfei, LIANGTao, ZHANGYuxiang, ZHANGJingke

2011, 24(3): 373-378. doi: 10.3969/j.issn.0258-2724.2011.03.003

[Abstract](1414)

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Abstract: To better protect earthen heritage sites, software FLAC3D was used to analyze the seismic response of the east temple pagoda of the Subashi Temple, and the seismic-induced displacement and stresses of the pagoda and the acceleration amplification factor and Fourier spectra of seismic waves were investigated. The results show that the pagoda produces a permanent displacement and has a tensile stress concentration under seismic loads. The seismic acceleration is weaken below the ground but amplified above the ground. The amplification factor of seismic acceleration raises with the increase of height away from the ground surface and reaches to 2.5 at the top of the pagoda. Both foundation soil and the pagoda top have a filter function to high-frequency waves, and low-frequency waves are amplified at the top of the pagoda.

Influence of Differential Shrinkage on Long-Term Deflection of Long-Span Continuous Rigid Frame Bridge

ZHANG Yuntao, MENG Shaoping, LIU Anzhong

2011, 24(3): 379-384. doi: 10.3969/j.issn.0258-2724.2011.03.004

[Abstract](1313)

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Abstract:
In order to fully consider the influence of differential shrinkage on the long-term deflection of a long-span continuous rigid-frame concrete bridge, formulas for calculating equivalent shrinkage strain were deduced based on a normal section assumption. Bar-system FEM (finite element method) was used to calculate the long-term deformation of Sutong continuous rigid-frame bridge due to differential shrinkage, and the equivalent shrinkage strain was simulated with the cooling method. The research results show that when the effect of differential shrinkage is considered the deflection at mid-span of Sutong continuous rigid-frame bridge is 6.0 cm larger than that based on the conventional method. The long-term deflection due to differential shrinkage resulted from different thicknesses of flanges is up to 5.5 cm, while it is only 0.5 cm due to differential shrinkage resulted from different ratio of reinforcement. The deformation due to differential shrinkage is significant and should be considered in camber setting of long-span concrete box girder bridges.

Simulation of Vehicle-Bridge Coupling Vibration for Yujiang River Bridge on Nanning-Guangzhou High-Speed Railway

CUIShengai|SHAN Deshan|ZHUBing

2011, 24(3): 385-390. doi: 10.3969/j.issn.0258-2724.2011.03.005

[Abstract](2064)

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Abstract:
In order to research the coupled vibration effects when a train runs through a long-span twin tower steel truss cable-stayed bridge at a high speed to provide a reference for the design of the same type of bridges, a numerical simulation model for coupled vibration was set up by taking Yujiang River bridge, a long-span steel truss cable-stayed bridge, on Nanning-Guangzhou high-speed railway as a study object. A dynamic analysis model for the bridge was established with the finite element software ANSYS, and its natural vibration properties were analyzed. A spatial dynamic model for German ICE3 train was set up by the multi-system dynamics software SIMPACK. The spatial coupled vibration responses of a vehicle-bridge system under the conditions of different strain speeds were calculated by co-simulation based on the SIMPACK and the ANSYS. The results show that when a strain runs respectively at a speed of 250, 270, 290 or 300 km/h, all its safety indexes can meet standard requirements, Sperling comfort indexes of motor car and trailer both are less than 2.5. The maximum vertical and lateral deflection-span ratios are respectively 1/1 843 and 1/83 000, the maximum vertical and lateral accelerations are 0.386 and 0.107 m/s2, respectively, and the maximum impact coefficient is 1.200. All these indexes show that the bridge has a sufficient rigidity, and its vibration is in good condition.

Experimental Investigation of Friction Properties between CFRP Main Cable and Saddle of Suspension Bridge

HOU Suwei, ZHUGE Ping, QIANG Shizhong, LI Cuijuan

2011, 24(3): 391-397. doi: 10.3969/j.issn.0258-2724.2011.03.006

[Abstract](1294)

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Abstract:
In order to investigate the friction properties between CFRP (carbon fiber reinforced plastics) main cable and saddle of a suspension bridge, the contact geometry and contact characteristics of main cable and saddle were analyzed theoretically. From the related formula for calculating the friction coefficient, parametric analysis of factors influencing the friction properties is conducted, static tests were designed and carried out under different parametric conditions. Theoretical and experimental results show that the friction coefficient between CFRP main cable and saddle was sensitive to the roughness of saddle surface and CFRP rod species, but the average radial pressure affects on the friction coefficient slightly. The friction coefficient between saddle and hot-extruded CFRP main cable, composed of hot-extruded CFRP rods with micro-embossed silks, is not sensitive to friction membrane, while the friction coefficient between saddle and cold-drawn CFRP main cable, composed of cold-drawn light circular CFRP rods, decreases with the appearance of the friction membrane. As a result, compared with the cold-drawn CFRP main cable, the hot-extruded CFRP main cable has excellent tribological properties. The friction coefficients between the two types of CFRP main cables and saddle are respectively about 0.5 and 0.3 to meet the design standards.

Lumped Mass Model for Dynamic Performance Simulation of Pantograph

ZHOU Ning, ZHANG Weihua, WANG Dong

2011, 24(3): 398-403. doi: 10.3969/j.issn.0258-2724.2011.03.007

[Abstract](1679)

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Abstract:
The pantograph was simplified as a model with two and three lumped masses to measure the dynamic performance of the pantograph. The parameters of the model, including the masses, stiffness and damping of the pan-head, the upper frame and the lower frame were identified experimentally. The dynamic contact forces between the pantograph and the catenary were calculated based on the parameters and compared with available experimental data, showing that the maximum errors of the maximum and minimum contact forces were 23.97 and 12.02 N for the pantograph model with three lumped masses, and 36.95 and 20.84 N for that with two lumped masses, respectively.

Fluid-Solid Coupling Vibration of Train Passing through Platform at High Speed in Cross Wind

CUITao, ZHANG Weihua

2011, 24(3): 404-408. doi: 10.3969/j.issn.0258-2724.2011.03.008

[Abstract](1444)

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In order to evaluate whether a train can pass through a platform safely at high speed in cross wind, the air-actuated response in this case was studied with both train aerodynamics and train system dynamics considering the track irregularity and the attitude changes of trains caused by cross wind. The attitude changes were obtained from the analysis of cross wind and train fluid-solid coupling vibration. The results show that, different from that the tailing vehicle is easy to collide with the platform in a no-wind environment, the closest point to the platform appear on the front-end of the leading vehicle when the train passing through the platform at the speed of 350 km/s in 6 m/s cross wind.

Motion Stability Analysis of Carrier Helicopter Traction System on Deck

ZHOU Lijie, WANG Nengjian, ZHANG Defu

2011, 24(3): 409-414. doi: 10.3969/j.issn.0258-2724.2011.03.009

[Abstract](1504)

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In order to study the dynamic performance of a helicopter traction system on deck, and analyze the factors influencing its motion stability, a dynamic model of the traction system was developed. In the model, the inertial force of the helicopter traction system produced by coupled roll-pitch-heave motion of the ship hull and the influence of variable vertical load on the tire cornering stiffness were considered. Based on this model, a 4 degree-of-freedom (DOF) perturbation equation with periodic coefficient was obtained, and the motion stability of the traction system was analyzed by the Floquet theory. The results show that the critical velocity of the traction system, compared with that on land, reduces sharply above sea state 2, with a magnitude not less than 70%; the traction motion stability increases as the mass ratio of helicopter to tractor decreases and the cornering stiffness of the tractor rear wheels increases.

Locomotion Analysis and Simulation of Piezo-Driven Miniature Robot

DU Qiliang, ZHANG Qin, TIAN Lianfang, AOYAMA Hisayuki

2011, 24(3): 415-421. doi: 10.3969/j.issn.0258-2724.2011.03.010

[Abstract](1028)

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A PZT(piezoelectric ceramic)-driven electromagnetic miniature robot which could fulfill the requirement of large range, high precision and omni-direction in a desktop factory was presented. With the cooperation of two electromagnets, the robot was able to move forward/backward, turn left/right, and rotate around its own center based on the stick-and-slip motion principle. On the assumption that the two parallel-setup piezoelectric actuators maintain parallel to each other in one step motion, coordinates of the four standing legs were analyzed, resulting in a locomotive differential model to reflect position and orientation changes. The calculated results showed that the maximum step length in rectilinear movement was 0.042 0 mm, while the maximum step degree in rotary movement was 0.185°/step. Experimental results of open loop trajectory control, point-to-point pose control and closed-loop path following control proved the effectiveness of the miniature robot when used in a desktop factory.

Investigations of Wind Loads on a New Type of Self-Supporting Four Pipe Steel Chimney

YU Kunlong, WANG Weihua, HUANG Hanjie, FANZhenzhong

2011, 24(3): 421-426. doi: 10.3969/j.issn.0258-2724.2011.03.011

[Abstract](1636)

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To reveal the wind load resistance characteristics of chimneys, wind tunnel testing and theoretical analysis were used to investigate the wind loads on a new type of self-supporting four-pipe steel chimney of 240 m height. With a large-scale rigid physical model, surface pressure measurement in a simulated atmospheric boundary layer flow field was made in the 8 m×6 m wind tunnel industrial test section at the China Aerodynamic Research and Development Center (CARDC). The wind pressure distributions and the body coefficients of the structure were obtained, and the along-wind equivalent wind load and the wind-induced vibration coefficients were calculated by the conventional inertial wind loading method in the code of China and the gust loading factor method in the code of other countries. The results show that the pressure coefficient distribution on each section of pipes is approximately similar, but the interference effect between pipes is remarkable. The integral body coefficient reach a maximum value of 0.633 at the wind direction angle 60°. The response of the along-wind fluctuating equivalent wind load is close to that of the mean wind load.

Design and Implementation of Mobile Agent-Based Spatial Information Sharing Service

ZHU Jun, HU Ya, CAO Yungang, GUO Fangtao

2011, 24(3): 427-433. doi: 10.3969/j.issn.0258-2724.2011.03.012

[Abstract](1114)

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Abstract:
To improve the efficiency of geospatial data cooperation under distributed, heterogeneous and dynamic environments, the mobile agent (MA) technology was used to construct geospatial information sharing service (GISS). The characteristics of the MA technology and the advantages of its application to GISS were discussed. A four-layer service framework and a function structure based on the MA technology were designed, and a dynamic control model of MA computing was established. In addition, implementing method of MA computing was given by taking a distributed service system of the risk assessment of barrier-dam break as an application example. The research results show that the mobile agent computing can avoid the transmission of spatial data in the network, enhance data security and improve the efficiency of data cooperation.

Construction and Adjustment Method for CPⅢ Trigonometric Leveling Network of High-Speed Railway

LIU Chenglong, YANG Xuefeng, LU Jiankang, HE Bo

2011, 24(3): 434-440. doi: 10.3969/j.issn.0258-2724.2011.03.013

[Abstract](1465)

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Abstract:
In order to establish CPIII vertical control network in high-speed railway with high efficiency and accuracy, a CPIII trigonometric leveling network method based on difference method was proposed, which was performed simultaneously during establishing the horizontal control network. In this method, a mathematical model of observation equations with weighted values, which are determined according to the error propagation relationship between indirect height difference and direct observations, is built, and the parameter adjustment method is used to obtain the accurate elevation values of CPIII control points. Then, a computing software based on the proposed algorithm was developed and tested in real application. The test result shows that the derived height from the proposed method, compared with the leveling height at the same point, has a confidence level of 99.40% for tolerance interval of -3 to 3 mm. Therefore, using the CPIII trigonometric leveling network obtained by the proposed method to replace the CPIII leveling network can meet the accuracy requirement of CPIII vertical control network.

Comprehensive Comparison and Analysis of VRS Dynamic Stochastic Modeling

XU Rui, HUANG Dingfa, CHEN Weifeng, LIAO Hua, FAN Lingchun

2011, 24(3): 440-444. doi: 10.3969/j.issn.0258-2724.2011.03.014

[Abstract](1240)

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In order to find an optimum stochastic modeling method for VRS (virtual reference station) systems, the principles of four stochastic models used in a real-time dynamic data processing system, including the standard stochastic model, the elevation-dependent model, the SNR (signal noise ratio) model and the self-adaptive model, were introduced, and their validity, advantages and disadvantages to a VRS system were analyzed from posterior variance, ADOP (ambiguity dilution of precision), F-ratio and filter residual. In addition, solutions to improve these models were given in the sight of statistics and their disadvantages. The results indicate that the filter residual and posterior variance obtained by the self-adaptive model change slightly around 0 and 1 respectively, showing the property of white noise. Furthermore, the advantage of the self-adaptive model in ADOP calculation is obvious, compared with the other models, however, it has an ordinary performance in F-ratio calculation. Totally speaking, the self-adaptive model should be the first candidate of a VRS stochastic model.

Features and Minimum Capacity of Active Compensation in Cophase Power Supply

ZHANG Xiufeng, XIEJie

2011, 24(3): 445-450. doi: 10.3969/j.issn.0258-2724.2011.03.015

[Abstract](1285)

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Abstract:
In order to determine the minimum capacity of an active compensation device, compensation current, compensation capacity and active filter capacity were analyzed. The research result shows that the capacity of an active compensation device has no matter with the load access port. To change the load access port can only influence the distribution of three-phase compensation currents, but not the capacity of the active compensation device. The capacity relates to the load capacity and power factor angle, and it ranges from 1.0 to 1.2 times the load capacity under full compensation when the power factor angle changes in (0, π). The capacity has no relation with the transformer connection mode, so to adopt a special transformer can not make any sense to the economic performance of an active compensation system.

Microwave Imaging of Perfectly Conducting Cylinder Based on Time Reversal and Single Antenna

ZHONG Xuanming, LIAO Cheng

2011, 24(3): 451-455. doi: 10.3969/j.issn.0258-2724.2011.03.016

[Abstract](1397)

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Abstract:
To reduce the effects of multi-path and highly reflective scatterers in a clutter environment, a microwave imaging algorithm for a perfectly electrical conducting target was proposed based on the adaptive focusing characteristic of time reversal (TR). In this algorithm, the contour of an unknown target is approximated by a trigonometric series. The scattering problem is simulated using the finite-difference time-domain (FDTD) technique, and the inverse problem is translated into a restrained optimization problem and the coefficients of the trigonometric series are optimized by the genetic algorithm (GA). With this algorithm, the image reconstruction of a two-dimensional perfectly electrical conducting target in a cluttered environment with many random scatterers can be done by only a single antenna. To demonstrate the validation of the proposed algorithm, the simulation of two numerical examples was carried out.

Hybrid Page Scoring Algorithm Based on Centrality and PageRank

QIAO Shaojie, PENG Jing, LI Tianrui, LI Hong, LI Taiyong, WANG Chao

2011, 24(3): 456-460. doi: 10.3969/j.issn.0258-2724.2011.03.017

[Abstract](1304)

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In order to score Web pages in an effective manner, a new page scoring algorithm, CentralRank, was proposed based on centrality measures, including degree, betweenness and closeness, and the PageRank algorithm. The CentralRank algorithm computes the importance of pages in Web social networks based on the centrality measures and employs the PageRank algorithm to accurately score Web pages. To verify the performance of the CentralRank algorithm, a Web crawler was developed to automatically and effectively crawl Web pages. The Web crawler contains three essential techniques, that is, Web data collection, content analysis and duplicate page detection. Experiments on real data show that the CentralRank algorithm can guarantee less time deficiency and is more exact in scoring Web pages than the centrality measures-based page ranking algorithm and the PageRank algorithm with an average improvement of 14.2% and 7.5%, respectively.

Incremental Algorithm of Pawlak Reduction Based on Attribute Order

GUAN Lihe, WANG Guoyin, YU Hong

2011, 24(3): 461-468. doi: 10.3969/j.issn.0258-2724.2011.03.018

[Abstract](1098)

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In order to update the attribute reduction of dynamic decision tables, an incremental algorithm of Pawlak reduction with a given attribute order was proposed based on a discernibility matrix element set. To different newly added objects this algorithm updates the discernibility matrix element set quickly. Thus, from the change of its elements the original Pawlak reduction can be updated effectively based on the given attribute order. An illustrative example and simulation experiment show that compared with the non-incremental algorithm, the proposed algorithm is efficient and feasible and has a 91.4% improvement in average efficiency.

LDPC-Coded Cooperative System Based on Joint Iterative Decoding

ZHANG Shunwai, YANG Fengfan, ZONG Peng

2011, 24(3): 469-475. doi: 10.3969/j.issn.0258-2724.2011.03.019

[Abstract](1218)

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In order to improve the performances of a communication system, new coded cooperative communication schemes employing regular LDPC (low-density parity-check code) and irregular systematic LDPC codes respectively were proposed, and the methods of constructing the double LDPC codes used by source and relay nodes were given. The overall parity-check matrix corresponding to the double LDPC codes was deduced, then the bilayer Tanner graph of the deduced parity-check matrix was given. A new joint iterative decoding algorithm based on the bilayer Tanner graph was used for decoding of the destination node. Theoretical analysis and simulation results show that the proposed ideal LDPC-coded cooperative schemes offer a significant performance gain over the coded non-cooperative scheme under the same conditions. Under the conditions of a BER (bit error rate) of 10-5 and 10 decoding iterations, the ideal regular LDPC and irregular systematic LDPC-coded cooperative schemes achieve respectively 1.0 and 0.6 dB gains over the coded non-cooperative scheme.

DistributedDetectionAlgorithmforLocal-BottleneckNodes ofWirelessSensorNetwork

LILei, LIFengrong, HUANG Heqing

2011, 24(3): 475-480.

[Abstract](1055)

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Abstract:
Toreducenetworkburden,theconceptoflocal-bottlenecknode-wasproposed, andadistributeddetectionalgorithmforlocal-bottlenecknodeswasgiven.Local-bottleneck nodeshaveasimilareffectonnetworkperformancewithbottlenecknodes,buttheirdetection ismorepracticable.Especially,toanetworkdeployedinabelt-typearea,itisprovedthatas longasthewidthoftheareadoesnotexceed 3/2timesofcommunicationradius,one-hop topologyinformationisenoughtojudgewhetheranodeisabottlenecknode.Theexperimental resultshowsthatwiththedistributeddetectionalgorithm,theprobabilityforanarbitrarynode tobecomealocal-bottlenecknodeisonly1/4ofthatforaquasi-bottlenecknodewhenthe averagenumberofneighbornodesis10,whichimprovesthedetectingaccuracyandreducesthe costofnetworkmaintenance.

Variational Inequality Model and Algorithm for Stream Line Network Optimization

ZHANG Jin, WANG Kun

2011, 24(3): 481-487. doi: 10.3969/j.issn.0258-2724.2011.03.021

[Abstract](1749)

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A simplified variational inequality model and its projection algorithm were proposed to optimize stream line networks that are complex hypernetworks. In the model, the objective is the matching degree between supply and demand, and the constraints are capacities and resources, and the model is converted to a variational inequality form. A case study on a logistics nodes allocation plan was presented. The result shows that the matching degree (0.999 7) by the projection algorithm is greater than that (0.947 6) by experience comparative method. It was proved that the proposed model has a unique solution.

Memetic Algorithm for Aircraft Arrival Sequencing and Scheduling Problem

MENG Xiangwei, ZHANG Ping, LI Chunjin

2011, 24(3): 488-493. doi: 10.3969/j.issn.0258-2724.2011.03.022

[Abstract](1627)

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In order to improve the local search capacity of genetic algorithms (GAs) in solving the aircraft arrival sequencing and scheduling problem in a multi-runway system, a mixed-integer zero-one quadratic programming model for the problem was built. Then, the proposition was proved that aircrafts of the same type should land on each runway in the order of their expected time of arrival under the first-come first-served policy, and a Memetic algorithm that couples the local improvement algorithm with the genetic algorithm was designed to solve the model. The computational results on several publicly available test problems show that the worst solutions found over ten replications of the Memetic algorithm are not inferior to the best solutions found by some existing GAs, and that the execution time is only 0.17 s for the problem involving 20 aircrafts and 5 runways, and hence is more suitable for real time application compared with the exact algorithm.

Optimal Pricing of High Speed Passenger Railway Based on Price Sensitivity of Passengers

MA Si, CHEN Lingjuan

2011, 24(3): 494-499. doi: 10.3969/j.issn.0258-2724.2011.03.023

[Abstract](1884)

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To optimize the fare of a high speed passenger railway line, passengers were divided into three groups according to their price sensitivities. The stochastic user equilibrium method was used to formulate an intermediate layer model for elastic demands to different types of transportation and a lower layer one for different transportation products within the railway, and a top layer model with the objective being to maximize railway income was built based on the intermediate and lower layer models. The intermediate and lower layer models were solved by the method of successive averages (MSA), and the whole three-level programming model was solved by a particle swarm optimization (PSO). The result of an example indicates that at the optimal price, a high speed passenger railway line will attract a larger proportion of travelers among different types of transportation and different transportation products within railway.

Optimization Algorithm of Military Airlift Loading Based on 0-1 Integer Linear Programming

MENGChong, SONG Huawen, CHENBaisong

2011, 24(3): 500-505. doi: 10.3969/j.issn.0258-2724.2011.03.024

[Abstract](1194)

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In order to make efficeient plans of military airlift loading, six types of equipment and materials to be loaded and six modes of material layouts in load-bearing space were designed by analyzing the characteristics of airlift materials and aircraft cargo hold. The three dimensional military airlift loading problem was then converted into a two-dimentional one to establish a mathematical model for the military airlift loading problem. By constructing space layout transform modes, the space layout restrictions were transformed to 0-1 integer linear ones, and the military airlift loading problem was solved as a 0-1 integer linear programming one. Simulation results indicate that the operation time of this algorithm is not more than 1 s, the average load ratio of the plan is 38.8%, and its average effective space utilization is 59.7%.

Improved Genetic Algorithm for Single Machine Scheduling Problems with Deteriorating Jobs

GUOPeng, CHENG Wenming, ZHANGZeqiang

2011, 24(3): 506-511. doi: 3969/j.issn.0258-2724.2011.03.025

[Abstract](1314)

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To reduce the computational load of the existing algorithms for solving the large-size single machine scheduling problem, an analysis was made of the scheduling rule of the problem with stepwise deteriorating jobs, and an improved genetic algorithm (IGA) based on local search was proposed to minimize the makespan. In the IGA, a linear order crossover operator and a mutation operator based on the property of deteriorating jobs sequencing were designed for the chromosome using job-based encoding. Moreover, a local search technique was incorporated to enhance the local search ability and speed up the convergence of the proposed algorithm. The experimental results show that the makespan of the IGA is averagely about 56.6% lower than that of the simulated annealing algorithm in the case of 40 jobs. The proposed algorithm can avoid the local optimal solutions and accelerate the convergence rate.

Spectra and Thermodynamic Properties of Bioactive C15H13N2S2 Molecules

LIXuemei, LIQuan, ZHANGJianping

2011, 24(3): 512-517. doi: 10.3969/j.issn.0258-2724.2011.03.026

[Abstract](988)

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In order to obtain the spectra data and thermodynamic properties at different temperatures of N-benzylidene-4-[(2-cyanoimino-1, 3-thiazolidine-3-yl)methyl-thiazole-2-amine (C15H13N2S2) bioactive molecules, geometry structure optimization and frequency calculation were made using the B3LYP method of the density functional theory, and the electronic absorption spectra in gas and different solvent were calculated using the DT-B3LYP method of the time-dependent density functional theory. The results show that the most stable optimized structure is in good agreement with the experimental crystal structure. The peak of absorption is located at 370 nm in gas, near ultraviolet band, and solvents have no effect on the transition property, but increase the absorption intensity obviously. Moreover, there is a linear positive correlation between standard molar entropy and temperature, and the correlation coefficient is 0.999 05.

Curing Kinetics of Nonmetallic Powder/Epoxy Resin Composites

WANG Xinjie, ZHANGJianqiang, GUOYuwen

2011, 24(3): 518-522. doi: 10.3969/j.issn.0258-2724.2011.03.027

[Abstract](1121)

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In order to determine appropriate curing conditions of the non-metallic powder (NM) and the epoxy resin system in a paper printed circuit board (PCB), differential scanning calorimetry (DSC) was used to study the curing processes of epoxy (EP system), non-metallic powder/epoxy resin composites (NM-EP system), and KH-550 treated non-metallic powder/epoxy resin composites (K-NM-EP system). The results show that the addition of PCB non-metallic powders in EP would increase the apparent activation energies (ΔE) of the curing systems, but this did not affect the curing reaction order. From the kinetics calculation, the best initial curing temperature and the post-treatment temperature are 333.15 and 453.15 K respectively for the EP sytem, 353.15 and 423.15 K respectivly for the NM-EP system, and 343.15 and 393.15 K respectively for the K-NM-EP system; and the curing temperature in all cases is 373.15 K.

Industrial Test of Concrete Packing for Gob-Side Entry Retained in Gently-Inclined Medium-Thickness Coal Seam

DENGYuehua, TANGJianxin, ZHUXiangke, FUYong, HU Hai

2011, 24(3): 523-528. doi: 10.3969/j.issn.0258-2724.2011.03.028

[Abstract](1211)

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In order to carry out gob-side entry retaining for a fully-mechanized coal faces in a gently-inclined medium-thickness coal seam to improve coal recovery, an integrated supporting scheme was proposed. In this scheme pumping concrete is used as filling material, single hydraulic props as temporary supporting on the both sides of concrete backfill and anchor cables as reinforce supporting along goaf. Proportioning tests on filling concrete were conducted in the lab, supporting parameters were determined based on the strata control theory, and an industrial test was carried through successfully in No.3117 fully-mechanized coal face in Jingang Coal Mine. The test result shows that roadside packing with ordinary concrete combining with single hydraulic props as temporary supporting can overcome the disadvantage of ordinary concrete in initial strength to effectively control roof strata.

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2011 Vol. 24, No. 3