西南交通大学学报

Temperature Control Strategy for Water-Cooled Proton Exchange Membrane Fuel Cells

CHEN Weirong, LI Yankun, LI Yan, ZHAO Xingqiang

2015, 28(3): 393-399. doi: 10.3969/j.issn.0258-2724.2015.03.001

[Abstract](1228)

Abstract:
An improved temperature control strategy by variation of air inlet pressure was proposed to solve the strong coupling problem that exists in the process of actual operation of a proton exchange membrane fuel cell (PEMFC) and to avoid the occurrence of instantaneous high temperature in the internal stack during a large amplitude. In order to adjust the cooling water inlet pressure, this strategy controls the velocity of cooling water by adjusting the speed of cooling water pump, and controls the inlet temperature of cooling water by regulating the rotational speed of the radiator fan. Taking into account the pressure-withstanding ability of stack plates, comparative experiments between the traditional control strategy and the improved control strategy were made on a self-developed multifunctional PEMFC test platform. The results show that the improved temperature control strategy could reduce the maximum overshoot of the cooling water inlet temperature by 34.7% and decrease the maximum difference between the cooling water inlet and outlet temperatures by 17.8%. Consequently, a higher control precision was achieved, and the response speed of system was improved with a maximum time reduction of more than 100 s when the current is reduced from 120 A to 90 A. Therefore, this strategy can meet the requirements on the temperature control of fuel cell systems.

Test Analysis and Modeling of Power Frequency Magnetic-Field Environment in Carbodies of Electrified Trains

ZHU Feng, LIU Guanghui, YE Jiaquan, DU Hui

2015, 28(3): 400-404. doi: 10.3969/j.issn.0258-2724.2015.03.002

[Abstract](1034)

Abstract:
In order to obtain the flux density and distribution characteristic of the power frequency magnetic field (PFMF) transmitted into the carbodies through windows of different electrified trains, the PFMF measurement data from high-speed, motor and ordinary cars were analyzed by GB/T24338 (Railway Applications Electromagnetic Compatibility). According to characteristics of traction power supply and carbody structure of electrified trains, a model for calculating the power frequency magnetic flux density from car windows was established, and the calculation results of the model were compared with the practical measurements to verify its effectiveness. The results show that the magnetic flux distribution obtained by the proposed theoretical model is consistent with the measurement data, and there is a positive correlation between the PFMF transmitted through vehicle windows and the traction current. The error between calculated results and measurements is within5%, which verifies the validity of the model.

Calculation Method for Rotor Slot Leakage Inductance of Virtual-Slot Short-Pitch Wave Winding

WANG Jianliang, LI Jinze, WU Bing, ZHANG Yihuang

2015, 28(3): 405-409. doi: 10.3969/j.issn.0258-2724.2015.03.003

[Abstract](851)

Abstract:
In order to calculate the slot leakage inductance of the virtual-slot short-pitch rotor winding in a doubly-fed induction generator (DFIG), the arrangement of a phase belt winding in the generator slot was studied from the structural principle of the virtual-slot short-pitch wave winding. Further, according to the self-induction and mutual-induction characteristics of conductors, the distribution of leakage flux linkage in the virtual slot of the short-pitch winding for rotor was derived by differential algorithm. Then, a calculation method was developed for slot leakage inductance of short-pitch windings with an odd and even number of virtual-slots, and its validity was verified through a case study. The results show that for the virtual-slot short-pitch winding, whether the number of virtual slots in the short-pitch windings is odd or even, the leakage inductance value is approximately the same. For the rotor using equivalent real slots, however, the leakage inductance is nearly twice that using virtual slots.

Self-excited Vibration of Single-Magnet Suspension System: Stability Analysis and Inhibition

LI Songqi, ZHANG Kunlun

2015, 28(3): 410-416. doi: 10.3969/j.issn.0258-2724.2015.03.004

[Abstract](1219)

Abstract:
The self-excited vibration occurs due to mutual coupling between EMS maglev vehicles and the track. In order to study its effect on the safety and comfort of vehicles, a vehicle body-suspension frame-track dynamic model for single-magnet suspension systems was established. Using this model, the stability of the vehicle-track system was analyzed together with the influence of the suspension controller and main system parameters on the vibration. Consequently, a relational expression between the system parameters and stability was proposed, and a specific method of using instantaneous optimal control algorithm to inhibit the self-excited vibration of the vehicle-track system was discussed. The inhibiting effect on self-excited vibration of the proposed algorithm was simulated under three groups of different system parameters. The results indicate that the vehicle structure, the suspension controller, and the main parameters of the track would influence each other in the vehicle-track self-excited vibration. At the time of 10 s after the simulation system started, the amplitude of the suspension air gap vibration in the three parameter configurations decreased by 59%, 62%, and 5% respectively; and the amplitude of track vibration decreased by 48%, 94%, and 73% respectively, which demonstrated the effectiveness of the proposed control method.

Speed-Sensorless Vector Control of Primary Cascaded Linear Induction Motor

MA Jiaqing, ZHOU Dajin, ZHAO Lifeng, ZHANG Yong, ZHAO Yong

2015, 28(3): 417-422. doi: 10.3969/j.issn.0258-2724.2015.03.005

[Abstract](964)

Abstract:
For investigating the performance of constant and adaptive speed regulation of cascaded linear induction motor (LIM) in maglev system, a new speed-sensorless vector controller was designed based on the Maxwell equations by analyzing the relationship between the thrust of the LIM and the current vector of the primary winding. The reasonability and the effectiveness of this controller were verified by numerical simulation using Matlab/Simulink. The results show that when facing small perturbation of the speed, the controller can automatically adjust the DC bus voltage of the rectifier through the inner current loop and the outer voltage loop to stabilize the speed within 10 ms. When receiving the reference speed value, the frequency of the AC side of the inverter is regulated to obtain a suitable value of the synchronous speed; the regulating time is less than 50 ms and within 3 cycles of power frequency, meeting the requirements of control performance in maglev system.

Effect of Initial Damage on Fatigue Performance of Welded Joints

JIE Zhiyu, LI Yadong, WEI Xing

2015, 28(3): 423-427. doi: 10.3969/j.issn.0258-2724.2015.03.006

[Abstract](1171)

Abstract:
In order to investigate the effect of initial damage of a welded joint on its fatigue life and damage evolution, adopting the damage variable based on crack size from the damage mechanics, two common fatigue damage evolution models, the Chaboche model and the Lemaitre model, were used to discuss the effect of the initial damage on the fatigue life and damage variable of the welded joint, and a concept of fatigue life reduction factor that is based on the initial damage was proposed. Then, the fatigue life reduction factors and fatigue damage curves under different initial damage were obtained from a non-carrying fillet welded joint in a case study. The results show that when the initial damage is less than 0.055 or 0.002, its effect on the fatigue life can be ignored in both the Chaboche model and the Lemaitre model. The Lemaitre model is more sensitive to the initial damage than the Chaboche model, and the Chaboche model is more appropriate to describe fatigue damage evolution of welded joints.

Predominant Direction and Mechanism of Landslides Triggered by Lushan Earthquake

DUAN Shusu, YAO Lingkan, GUO Chenwen

2015, 28(3): 428-434. doi: 10.3969/j.issn.0258-2724.2015.03.007

[Abstract](1101)

Abstract:
Based on Lushan earthquake records, drainage systems and 1 754 earthquake-induced landslides, control factors of the directions of landslides triggered by earthquake were researched. The dominant direction of landslide number and the dominant aspect of natural slopes were compared; the direction of new tectonic stress field in the Lushan seismic area was determined from the antagonism principle; the certainty factor for landslide in each sub-area was determined by GIS spatial analyses. The research shows that the predominant direction of natural slopes is a control factor of the directions of landslides triggered by an earthquake, but the asymmetry of mountain slope landform should be considered; the direction of new tectonic stress field is a global factor of the directions of landslides; the direction of the maximum cumulative acceleration at a seismic station also control the sensitivity directions of landslides in the station area; to an earthquake resulted from a blind fault, it may be a universal law that the above three factors control the direction of earthquake-triggered landslides.

Analytical Solutions of Earthquake Dynamic Responses of Trapezoid-Like Mountain

ZHANG Yingbin, YU Pengcheng, ZHAO Xingquan

2015, 28(3): 435-441. doi: 10.3969/j.issn.0258-2724.2015.03.008

[Abstract](1050)

Abstract:
In order to investigate the effect of earthquake loading on the dynamic responses of a mountain, a shear-beam model, an analytical method, for trapezoid-like mountains with two curved slopes was set up. The analytical solutions of the dynamic responses were obtained. A simplified empirical expression of the first order natural frequency of a trapezoid mountain was given. The maximum relative displacements, maximum relative velocities and maximum absolute accelerations of trapezoid and trapezoid-like mountains were calculated and compared with those obtained by FEM (finite element method). The research results show that the trapezoid model is easy to obtain the responses, but the trapezoid-like model is more accuracy. The analytical solutions are close to those obtained by FEM under the condition of a small moment. The first order natural frequency of a mountain increases slightly with the growth of Poisson's ratio. The maximum relative displacements and maximum relative velocities of a mountain become larger from its bottom to its top, while its maximum absolute accelerations reach the minimum at the height of its approximately 2/5 height.

Localization Method of Seismic Target in Anisotropic Ground

LU Zhiwen, DONG Dawei, HUA Chunrong, YAN Bing, XIE Xiao, CHEN Jun

2015, 28(3): 442-448. doi: 10.3969/j.issn.0258-2724.2015.03.009

[Abstract](830)

Abstract:
In order to solve the problem of low seismic target localization accuracy due to propagation speed variation in anisotropic ground, a novel target localization method was proposed based on the time difference of arrival (TDOA) from the time delay-equivalent propagation speed search table through transforming a position-related propagation speed into a time delay-related equivalent propagation speed. A simulation was carried out to investigate the localization ambiguity area with a right isosceles triangle sensor array. To eliminate this ambiguity area, a five-sensor cross array was put forward. A field experiment was conducted to locate a moving vehicle. The localization results based on the proposed method and the traditional TDOA based method assuming a constant propagation speed of seismic signal were compared with. The comparison result shows that compared with the traditional TDOA based method, the proposed method is much more efficient.

Seismic Analysis Method of Deep-Water Bridge Pier and Water Coupling

LIU Lang, YANG Wanli, LI Qiao

2015, 28(3): 449-453. doi: 10.3969/j.issn.0258-2724.2015.03.010

[Abstract](1047)

Abstract:
To adopt a right method to calculate hydrodynamic pressure, a novel method, combining the Morison equation with CFD (computational fluid dynamics), for calculating the seismic responses of a deep-water bridge under pier-water coupling was proposed. The results based on the ANSYS-CFX model show that the proposed method can calculate the seismic responses of a deep-water bridge under pier-water coupling effectively. A deep-water environment will decrease the maximum elastic displace-ment at pier top, but it will increase the maximum rigid displacement and the total stsructure displacement. Additional hydrodynamic pressure generated by rigid motion plays a major role, and the effect of elastic vibration must be considered.

Temperature Field Test of CRTS Ⅰ Twin-Block Ballastless Track in Winter

YANG Rongshan, WAN Zhangbo, LIU Xueyi, ZHANG Zhongwang, ZHAO Pingrui

2015, 28(3): 454-460. doi: 10.3969/j.issn.0258-2724.2015.03.011

[Abstract](1056)

Abstract:
In order to investigate the temperature distribution of ballastless track, the variation of track structure temperature field in different weather situations was analyzed from the temperature field monitoring of CRTSⅠtwin-block ballastless track in winter in Chengdu. Based on the mathematical statistics method, the temperature load mode of ballastless track slab located in Chengdu was put forward. The test result shows that temperature in track slab changes dramatically in a day, but temperature in hydraulic bonded layer changes slowly; the maximum temperature difference on track slab surface is 17.50 ℃, and it is only 0.35 ℃ in the hydraulic bonded layer; the changing rate of temperature in track decreases with depth, and the peak of temperature in track appears later than the peak of air temperature; the maximum positive temperature difference of track structure appears at about 14:30, and the maximum negative temperature difference appears at about 08:00; temperature in track slab assumes an exponential function relation along the depth.

Analysis-Oriented Stress-Strain Model of CFRP Confined Concrete with Preload

PAN Yi, WAN Li, WU Xiaofei

2015, 28(3): 461-465. doi: 10.3969/j.issn.0258-2724.2015.03.012

[Abstract](878)

Abstract:
In order to investigate the effect of preload ratio on the peak stress and peak strain of FRP (fiber reinforced plastics) confined concrete columns, based on the experimental analyses of 32 CFRP (carbon FRP) confined concrete circular columns and 16 CFRP confined square concrete columns, a preload factor was considered to modify the J G Teng's formulas of peak stress and peak strain of CFRP confined concrete column. Based on the above the axial-lateral strain relationship of CFRP confined concrete was analyzed, and an analysis-oriented stress-strain model was set up by considering the effect of preload and taking the constitutive model purposed by J G Teng as an active confined relation. The research results show that the stress-strain relationship is consistent with the experimental result, and modified peak stress and peak strain agree well with the test results, and the error margins for the circular column specimens and square column specimens are about 10% and 15%, respectively.

Improvement Measures for Layer Limits and Tie Column Settings in Masonry Structures

SU Qiwang, XU Hu, ZHAO Shichun, SONG Jirong

2015, 28(3): 466-471. doi: 10.3969/j.issn.0258-2724.2015.03.013

[Abstract](735)

Abstract:
In order to make up for some deficiencies in layer limits and tie column settings for brick masonry structures in seismic design code, where the provisions of layer limits and tie column settings are presented without considering the difference in wall area on a floor, an index of the ratio of wall areas in load-bearing direction to the floor areas (RWF) was proposed. Some differences in RWF due to different types and construction ages were studied by a statistical analysis of a lot of design data. In addition, according to the seismic evaluation theory and its judgment standard, the influences of RWF on layer limit and tie column setting were analyzed. Some suitable measures of layer limits in different performance target and structural columns settings were also suggested. The analysis results show that, in order to meet the requirement of a structure does not collapse in a major earthquake, the RWF of a seven-storey brick masonry structure with assembled slabs subjected to seismic fortification intensity of 7 degree shall not be less than 5.5%, and the RWF of the structure with cast-in-situ slabs shall not be less than 4.5%; the RWF of a six-storey structure with assembled slabs subjected to seismic fortification intensity of 8 degree shall not be less than 6.5%, and the RWF of the structure with cast-in-situ slabs shall not be less than 5.5%; the RWF of a four-storey structure with assembled slabs subjected to seismic fortification intensity of 9 degree shall not be less than 6.5%, and the RWF of the structure with cast-in-situ slabs shall not be less than 5.5%.

Extraction of Fluctuating Pressure on High-Speed Train Surface Based on Wavelet Transform

CHEN Chunjun, HE Hongyang, SHAO Yunlong

2015, 28(3): 472-477. doi: 10.3969/j.issn.0258-2724.2015.03.014

[Abstract](1063)

Abstract:
It is always the case that micro-piezoresistive pressure sensors are affected by some interference signals during the process of measuring the high-speed trains' surface pressure, which makes signal to noise ratio (SNR) of the fluctuating pressure low. In order to extract the fluctuating pressure effectively, a sensor output model was established. An effective denoising method based on wavelet threshold was proposed, which determines the decomposition level by introducing a correlation coefficient and counts the stratification threshold according to 3 principle. This method was then used to denoise static test signals of a certain type of CRH EMUs (electric multiple units) and extract the fluctuating pressure from the surface pressure of the EMUs at 200 km/h, and on this basis to build a power spectrum model of fluctuation pressure. The results show that the proposed method can extract the fluctuating pressure effectively, and the pressure at measuring points fluctuates constantly in the amplitude range of 20 Pa and mainly in the frequency range of 0-200 Hz. The established power spectrum model of fluctuating pressure provides a theoretical guidance for the vibration damping and noise reduction of trains.

Analysis of Network Security for Chinese High-Speed Railway Signal Systems and Proposal of Unified Security Control

LI Saifei, YAN Lianshan, GUO Wei, GUO Jin, CHEN Jianyi, PAN Wei, FANG Xuming

2015, 28(3): 478-484,503. doi: 10.3969/j.issn.0258-2724.2015.03.015

[Abstract](1469)

Abstract:
In order to ensure the network security of China's high-speed railway signal system, the network security issues including the central traffic control (CTC) system, train control system, centralized signal monitoring system and the GSM-R system were analyzed generally. Subsequently a unified network security control and management strategy was proposed based on the software-defined networking (SDN) architecture. The centralized management and unified security policies are achieved in one physical network, and the original control logics between sub-networks including CTC network, train control network and centralized signal monitoring network are all software-defined in the control plane, which enables the finer and unified control of the whole network. Using the logically centralized controller, the unified device register control, communication control and packet traceability are all achieved, thus improving the network security and reducing the management complexity. According to the analysis, the proposed architecture is centrally managed, network programmable and unified of the security policy. The proposed strategy is better than the distributed control network for the management of China's high-speed railway signal system network security and can solve the complex management of networks' interconnection of different security levels.

New Mathematical Model for GNSS Relative Positioning Resolving

ZHANG Xi, HUANG Dingfa, LIAO Hua, FENG Wei

2015, 28(3): 485-489. doi: 10.3969/j.issn.0258-2724.2015.03.016

[Abstract](766)

Abstract:
In order to overcome the problem of the traditional model, a new model was proposed for relative positioning resolving of global navigation satellite system (GNSS). With the coordinates of reference station known in advance, this model is different from the traditional model that its coefficient matrix remains unchanged in resolving, so it is convenient to describe the converging process of the least squares and benefit for error analysis and improving search efficiency in coordinate domain, and this model has certain application potentiality. The experimental results show that the proposed model has the same position accuracy as the traditional model, i.e., the first-order Taylor series expansion, to verify its validity and reliability, so it can be used to replace the traditional model in relative positioning.

An Improved SIFT Algorithm for Image Stereo Matching

LI Dan, SUN Haitao, WANG Haili

2015, 28(3): 490-496. doi: 10.3969/j.issn.0258-2724.2015.03.017

[Abstract](1452)

Abstract:
The high complexity and long computing time of SIFT (scale invariant feature transform) algorithm affect the real-time ability of stereo matching. To solve this problem, an improved feature-points matching algorithm of stereo vision was proposed. The SIFT algorithm was improved in two aspects. First, 24-dimensional feature descriptor instead of 128-dimensional feature descriptor was used to reduce computational complexity. Then the improved BBF search algorithm was used in the process of image matching, so that the feature point matching of the two images can be determined through the minimum priority queue restrictions and the Mahalanobis distance of higher matching accuracy. The classical images and images taken at unknown outdoor environment were used to validate this algorithm. Experimental results show that the proposed algorithm spends 0.01 s to detect 100 feature points, and the average correct matching rate is 89.65%. Compared with the original algorithm, it improves the matching accuracy and reduces the matching time.

A Map-Matching Algorithm Based on Improved AOE Network for Low Frequency Floating Car Data

SHEN Jingwei, ZHOU Tinggang, ZHANG Hongtao

2015, 28(3): 497-503. doi: 10.3969/j.issn.0258-2724.2015.03.018

[Abstract](1080)

Abstract:
Due to the long time interval characteristic, the existing map-matching algorithms are not suitable for the low-frequency FCD (floating car data). By analyzing local map-matching algorithms and global map-matching algorithms, and overall considering the FCD trace, a map-matching algorithm for low-frequency FCD based on improved AOE (activity on edge) network was proposed. Firstly, intersection analysis between a buffer around a GPS point and road segments was carried out to acquire the candidate road segments and candidate map-matching points. Secondly, quadtree spatial index and Dijkstra algorithm were introduced to obtain the shortest path between the adjacent candidate map-matching points. Thirdly, the improved AOE network was built to search the FCD shortest path and the map-matching points were acquired. Lastly, the proposed algorithm was evaluated in terms of time efficiency and accuracy. Results show that the accuracy of the proposed algorithm is 95.3%, and the total program execution time is 96.8 s. The accuracy is respectively 13.6% and 2.8% higher than that of the local map-matching algorithm and global map-matching algorithm.

Effects of In-vehicle Information on Driver Eye Blink Duration and Workload

ZHU Tong, WU Ling, LU Qiaozhen

2015, 28(3): 504-510. doi: 10.3969/j.issn.0258-2724.2015.03.019

[Abstract](1301)

Abstract:
A real-vehicle experiment was conducted to study the effects of in-vehicle information systems on driver workload. Data of driver blink duration and frequency were collected with in-vehicle equipment mounted at three different positions. Driver blinking characteristics were studied for the navigation system providing image route information or image and sound route information. The distributions of blink duration and count with and without using route navigation were compared. Experimental data show that the blink count has dramatic bimodal distribution when blink duration ranges from 0 to 200 ms with an interval of 10 ms. Without using route navigation, blink counts between 50 and 60 ms are lower than those between 10 and 20 ms, while the results are converse using route navigation. The positions of navigation system return no significant effect in the counts of medium and long blinks while return significant effect on short blink count. Without sound route information, the double peak values of blink count are larger than the case with sound route information. Besides, short blink counts increase most noticeably, and then medium blink counts, while long blink counts nearly remain constant. This demonstrates that using the navigation system increases driver mental workload, and when the navigation system is mounted on the stands, the workload is the minimum. With sound route information, the workload is decreased.

Time-Varying Signal Compression Technology Based on Compressed Sensing

GUO Liang, GAO Hongli, HUANG Haifeng, ZHANG Xiaochen

2015, 28(3): 511-516. doi: 10.3969/j.issn.0258-2724.2015.03.020

[Abstract](1064)

Abstract:
Data compression and de-noise play important roles in the real-time storage and remote transmission of vibration signal for the on-line monitoring and fault diagnosis of mechanical equipments. By analyzing the time-varying characteristics of vibration signals, the sparse transfer matrix and compressing sensing matrix which satisfying the restricted isometric property (RIP) were constructed. Then, the signal compression and de-noise method was proposed based on compression sensing. The Lasso algorithm was used to reconstruct the compressed vector to restore raw signal. The proposed method was applied to analyzing the simulation and spindle vibration signal and was compared with the wavelet-based technique. The experimental results show that the proposed method is more effective in data compression and de-noise, and when the signal compression rate is 40%, the energy retention rate exceeds 95% to meet industrial requirements.

Topic Link Detection Method Based on Semantic Similarity

ZHAI Donghai, CUI Jingjing, NIE Hongyu, DU Jia

2015, 28(3): 517-522. doi: 10.3969/j.issn.0258-2724.2015.03.021

[Abstract](859)

Abstract:
To effectively judge the similarity between the topics of any two of stories, a topic link detection method was proposed on the basis of semantic similarity. First, the relative entropy between the feature words in two stories was calculated to work as the semantic similarity. Furthermore, the relevance between the feature words and the other story was obtained by calculating the average semantic similarity. At last, the relevance degree between two stories was calculated by considering TF-IF(term frequency-nverse document frequency)weights of the feature words in the corpus and the semantic similarity simultaneously, completing the link detection of the story pairs. The proposed algorithm was compared with the VSM (vector space model) method and average point-wise mutual information. The experimental results for Chinese Corpus of TDT4 show that minimum DET(detection error tradeoff)cost of the proposed algorithm is reduced by about 3%, which demonstrates that the proposed algorithm can impose the context information effectively and improve the performance of the topic link detection system simultaneously.

Prediction Model for Octane Number and Component Proportions of Gasoline Surrogate Fuel

ZHENG Zhaolei, QIN Yanxin

2015, 28(3): 523-528,549. doi: 10.3969/j.issn.0258-2724.2015.03.022

[Abstract](855)

Abstract:
The response surface method (RSM) was used to build models for predicting the octane number and determining the component proportions of a gasoline surrogate fuel, which is synthesized using toluene, is-octane and n-heptane and referred to as toluene reference fuel (TRF). The models, including the first-order model (FOM), the second-order model (SOM) and the third-order model (TOM), are compared in predicting the octane number of gasoline surrogate fuel with predefined component proportions of TRF. As a result, both the SOM and TOM show much better performances than the FOM in predicting the research and motor octane number, with predefined component proportions of TRF. Furthermore, the TOM shows greater accuracy than the SOM in determining the component proportions of TRF with predefined octane number, and the relative error is less than 8%. Therefore, the TOM based on RSM can accurately predict the octane number and determine the component proportions of TRF.

Impact of Curbside Parking on Bicycle Lane Capacity

YE Xiaofei, DENG Shejun, CHEN Jun, ZHENG Jingheng

2015, 28(3): 529-535. doi: 10.3969/j.issn.0258-2724.2015.03.023

[Abstract](1102)

Abstract:
In order to provide a theoretical basis for optimization and setting of the curbside parking on bicycle lanes, the traffic conflict technique was used to analyze the effect of curbside parking on the bicycle flow in segregated bicycle lane and establish a basic capacity model under the influence of curbside parking. On this basis, adjustment factors of the basic capacity were calculated by considering the influential factors of the capacity including the effective width, the traffic composition, and the time influence rate. Then an actual bicycle capacity model under influence of curbside parking was established. Application results show that the bicycle lane capacity is decreased by approximately 14.04% under the influence of curbside parking. The absolute error between the observed capacity and the estimated capacity is only 4.56%. The berths near the openings of isolation belt have less influence than in the middle position.

Human Performance in Vessel Passages Based on Improved TOPSIS Method

LIAO Quanmi, HUANG Sheng, WANG Yu, LI Xiang

2015, 28(3): 536-542. doi: 10.3969/j.issn.0258-2724.2015.03.024

[Abstract](811)

Abstract:
To deal with the lack of design basis of passages during the initial vessel design, an evaluation index system of accessibility that is based on human factors engineering was built according to the feature of interaction between passage design and crew operation. An improved TOPSIS method was proposed by combining TOPSIS (technique for order preference by similarity to ideal solution) and grey relational method. Then, a human performance evaluation method was presented on the basis of accessibility and space resource. The changes of human performance of two single-passage alternatives and two double-passage alternatives with different crew numbers (100, 150, and 200 persons) were analyzed after the calculation of accessibility of four alternatives. The results show that when the crew number rises from 150 to 200 persons, the human performance of the single-passage alternative declines obviously, but the double-passage alternative begins to show its superiority. To optimize the accessibility and utilization of space resource for a high human performance, the passages design should be simulated and evaluated based on crew numbers.

Optimal Intermodal Transport Path Planning Based on Martins Algorithm

LIN Feng

2015, 28(3): 543-549. doi: 10.3969/j.issn.0258-2724.2015.03.025

[Abstract](1025)

Abstract:
In order to select optimal paths quickly and efficiently, a multi-objective multimodal multi-commodity routing model with time windows was proposed on the basis of the existing model. A two-layer search algorithm was designed to solve the model. In the first layer, a revised Martins label setting algorithm and two time constraints are combined to calculate the effective paths based on the labels of paths. In the second layer, the effective solution of the above algorithm is considered as the initial solution, and optimal paths are obtained by removing the paths which do not meet the three restrictive conditions in transport time of cargoes, transfer times, and capacity limitation of transport mode. Then, a technique for order preference by similarity to an ideal solution (TOPSIS) was used to calculate integrated weights by combining different cost weights and time weights together, so as to find the optimal paths with the maximum integrated weight value. The result of an application example shows that, compared with the existing labeling algorithm, the proposed algorithm can reduce the search space and avoid generating invalid solutions by including capacity limitation of transport mode; compared with the Lagrangean relaxation method which can only generate the lower and upper bounds on the optimal solution, the proposed algorithm can obtain exact solutions within 30 min, computing time being reduced by about 75%.

Business Model-Driven Ontology Knowledge Representation and Application for Emergency Logistics

ZHANG Li, WANG Qianzhu, NING Yahui, JIANG Dali

2015, 28(3): 550-556. doi: 10.3969/j.issn.0258-2724.2015.03.026

[Abstract](847)

Abstract:
To solve the problem of heterogeneous information integration and knowledge management in the emergency logistics intelligent collaboration, aiming at the effective knowledge application, an ontology modeling method was proposed by utilizing the internal mapping of components and the business inference rules between business model and ontology model, involving relations among three modules and a four-step transformation process. Based on the suggested modeling method, an emergency logistics ontology model composed of concept aggregation, concept attribute, semantic restriction, and reasoning rules was constructed. As a case study, an emergency distribution routing problem was addressed by implementing the ontology model and reasoning out the neighboring alternative nodes. The result shows that the proposed ontology model and its application can achieve the heterogeneous information integration with ontology, eliminating the conventional retrieval invalid phenomenon, satisfying the conditions of the shortest path routing, and providing the knowledge base for the emergency logistics decision-making model and its algorithm application.

Game-Based Analysis on Motive of Regional Air Route Cooperation

WANG Kun, ZHU Jinfu, ZHU Xinghui

2015, 28(3): 557-561. doi: 10.3969/j.issn.0258-2724.2015.03.027

[Abstract](796)

Abstract:
Since the independent regional air route operates at a low level of profitability because of small transport volume and high operation cost, the BERTRAND game model was used to analyze the effect of the cooperation of the regional air route with branch air route on its operating profit from the point of market game. Regional air route was divided into two types, point to point and hub-spoke. Market structure models of cooperation and non-cooperation between regional air route and branch air route were built respectively for the origin-destination regional markets without point to point air route and with both point to point and hub-spoke air route. Total equilibrium profits under different market structures were compared. The results show that total profits of cooperative market structures are higher than those of noncooperation.

Forecast Method for Medium-Long Term Air Traffic Flow Considering Periodic Fluctuation Factors

CHEN Dan, HU Minghua, ZHANG Honghai, YIN Jianan

2015, 28(3): 562-568. doi: 10.3969/j.issn.0258-2724.2015.03.028

[Abstract](1130)

Abstract:
To accurately characterize the trend and periodic fluctuation of the future traffic demand in a specific airspace unit, an improved dynamic linear model that is based on the linear growth model was developed to forecast the medium-long term air traffic flow, by taking into full account periodic fluctuation factors such as the climate influence, seasonal fluctuation, actual traffic demand, and so on. Then, the Bayesian state estimation and forecasting method was used to solve the proposed model, and the medium-long term air traffic flow and its variation trend was predicted using the historical data of air traffic flow in a specific airspace unit. In addition, a case study on a real data set of a typical domestic airspace unit was carried out to compare the forecasting performance of the models. The results show that, compared with the linear growth model not considering periodic fluctuation factors, the air traffic flow obtained by the improved model has a periodic fluctuation characteristic, and is more in line with the real situation of air transportation in China; simultaneously, the mean absolute error of the yearly traffic flow decreases from 3.14% to 1.71%, and the standard deviation of forecast error decreases from 2.01% to 0.02%.

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2015 Vol. 28, No. 3