西南交通大学学报

Rain-Wind-Induced Vibration of Cables in Cable-Stayed Bridges (Ⅰ): Mechanism Analysis

LI Yong-Le, XU Yao-Lin, CHEN Ji-Min, CHEN Bo

2011, 24(4): 529-535. doi: 10.3969/j.issn.0258-2724.2011.04.001

[Abstract](2182)

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Abstract:
In order to explore the mechanism of rain-wind-induced vibration of cables, a modified model for rain-wind-induced vibration of cables was proposed based on aerodynamic coefficients tested by a spatial model with three-dimensional ambient flows. Furthermore, the feasibility of the modified model was verified through a comparison between analytical results and the ones obtained by wind tunnel tests. The characteristics of rain-wind-induced vibration were explored from the aspect of vibration energy. The research indicates that the rain-wind-induced vibration of cables is a type of galloping with a limited amplitude induced by negative slopes of aerodynamic lift coefficients and has the properties of self-excitation and limited amplitude vibrations.

Stochastic Responses of Train-Bridge Coupling System for Simply-Supported High-Speed Railway Bridge

ZHU Yan, LI Xiao-Zhen, QIANG Shi-Zhong

2011, 24(4): 535-540. doi: 10.3969/j.issn.0258-2724.2011.04.002

[Abstract](2082)

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In order to analyze the stochastic responses of a train-bridge coupling system in high-speed railway, the pseudo-excitation method (PEM) was applied to transform a vertical track profile irregularity into the superposition of harmonic excitations at a series of frequency points to translate a non-stationary random vibration problem into a deterministic time history problem. The method of separate iteration was used to solve the equations for the coupling system. The maximum and minimum responses of the coupling system were obtained based on the thrice standard error principle. The change regularities of the stochastic responses under different train velocities were discussed. The results show that the vertical displacement and acceleration of car body have large randomness, and the vertical responses of the mid-span of a bridge and the vertical wheel/rail force are influenced by the deterministic load. Train velocity has a significant influence on the maximum vertical acceleration of the mid-span and the maximum and minimum vertical accelerations of the car body.

Effective Stiffness Method for Calculation of Deflection of Composite Beams

ZHOU Dong-Hua, SUN Li-Li, FAN Jiang, ZHAO Zhi-Man, LIU Yong-Fang

2011, 24(4): 541-546. doi: 10.3969/j.issn.0258-2724.2011.04.003

[Abstract](1691)

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Accurate calculation of deflection of composite beams with elastic shear connections is difficult because of difficultly getting an analytical solution under an arbitrary load, and analytical solutions in common load cases are quite complicated. For these reasons, a simplified calculation method called method of reduction of stiffness was provided in Chinese Code for Design of Steel Structures. However, the results obtained by the method are not accurate enough and its application is limited under some circumstances. In order to solve the above problem, a new method called effective stiffness method was proposed. Calculations with this method are simple and accurate, and the proposed method has a clear mechanic background and can give a composite factor showing the actual effect of shear connections. It can be used to composite beams with an arbitrary stiffness of shear connections, i.e., from near zero to infinity. The calculation results show that the relative error between its solutions and analytical solutions is less than 1.0%.

Experimental Investigation on Load-Slip Relationship of Perfobond Rib Shear Connectors

WANG Zhen-Hai, ZHAO Can-Hui, LI Qiao

2011, 24(4): 547-552. doi: 10.3969/j.issn.0258-2724.2011.04.004

[Abstract](1250)

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In order to investigate the structural behavior of perfobond rib shear connectors in the whole load-bearing process, 37 specimens of perfobond rib shear connectors, sorted into 11 groups, were tested in the failure test under static loading. The load-slip curve in each working region and failure mode was studied, the influences of the shear stiffness of concrete bars and the tension bearing capacity of perforated rebar on the load-slip relationship were analyzed using the normalization method, and a uniform calculation formula of load-slip relationship was established. The results show that the load-slip relationship in elastic region is linear, whose slope is mainly affected by the shear stiffness of the concrete bars. In elastoplastic and hardening regions, the load-slip relationship is a power law, whose coefficient is linear with the shear stiffness of concrete bars and the tension bearing capacity of steel bars. The rational diameter of the steel bars in the perfobond rib shear connector with concrete bars of diameter 60 and 45 mm, is 20 and 16 mm, respectively.

Experimental Research of Anchored System for Longitudinal Connected Ballastless Track in High-Speed Railway

WEI Qiang, ZHAO Guo-Tang, GAO Yong-Jie, CAO Xiao-Pei, FU Qi-Zhang

2011, 24(4): 553-558. doi: 10.3969/j.issn.0258-2724.2011.04.005

[Abstract](1811)

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In order to get the rational relationship of interaction between bridge and rail, an anchored system for longitudinal connected ballastless track was designed, and a field experiment was carried out. The regularities of changes in the stress and displacement of the anchored system and distribution of soil pressure on subgrade under the design loads were obtained through monitoring and analyzing the stress, displacement and soil pressure. The experimental results show that an anchored system with double-pillar type main end thorns meets the demand of design and can be as a fine candidate for the design of CRTS (China railway track system) Ⅱslab ballastless track in high-speed railway.

Model Test of Water Content Control of Saturated Over-Wet Soil

HU Qi-Jun, WEN Hua, GONG Cheng, WANG Tian-Heng

2011, 24(4): 558-563. doi: 10.3969/j.issn.0258-2724.2011.04.006

[Abstract](1466)

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In order to probe into the approaches and effects of reducing the water content in saturated over-wet soils in moist and rainy areas, the water drainage effects of the vacuum preloading method and electro-osmosis method were compared via indoor model tests. The result indicates that the both methods can effectively reduce water contents in saturated over-wet soils and obtain the desired effects of drainage and consolidation, but there exists inhomogeneity in the spatial distribution of water-reducing content when they are used. When the vacuum preloading method is adopted, water contents in top and bottom soil layers do not change significantly, and consolidation effect is relatively homogenous.

Prototype Test on Failure Characteristics of Segmental Lining Structure for Nanjing Yangtze River Tunnel

FENG Kun, HE Chuan, SU Zong-Xian

2011, 24(4): 564-571. doi: 10.3969/j.issn.0258-2724.2011.04.007

[Abstract](1487)

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In order to research the failure characteristics of segmental lining structure for Nanjing Yangtze River tunnel, a prototype test was carried out by using a “multi-function shield tunnel structure test system”. Water pressure and earth pressure were applied separately upon the prototype segmental lining structure in the test. And the failure characteristics of underwater shield tunnels under straight or staggered assembling were discussed respectively. The research results show that the damages of Nanjing Yangtze River tunnel are resulted mainly from bend cracking. Bend crack developing is always accompanied by the remarkable development of structure deformation and segment joint opening. The features of segment joint opening, cracking and deformation developing are different to the two different types of assembling structures. Compared with a straight assembling segmental structure, a staggered assembling segmental structure has a small deformation and crack width but fast cracking speed

Robust Controller of Self-Powered Active Suspension

SONG Peng-Yun, ZHANG Ke-Yue, ZHANG Ji-Ye

2011, 24(4): 572-578. doi: 10.3969/j.issn.0258-2724.2011.04.008

[Abstract](1280)

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In order to improve the stability, vibration isolation and energy feedback performance of self-powered active suspension systems with parameter uncertainty for vehicles, a robust controller was designed for the system model with perturbation, and the energy equilibrium condition was given. The control system was simulated using MATLAB/SIMULINK. The results indicat that the robust controller made the self-powered active suspension system stable. Compared with traditional optimal controller, the vibration isolation performance was improved obviously. The root-mean-square values of the control force, suspension working space, dynamic tyre displacement, and vehicle body acceleration were reduced by 45.19%, 52.15%, 61.19%, and 15.79%, respectively. During the whole simulation process, an energy of 1 831 J was recycled.

Calculation and Optimization of Train Headway in CBTC System

CHEN Rong-Wu, CHU Chang-Han, LIU Li

2011, 24(4): 579-585. doi: 10.3969/j.issn.0258-2724.2011.04.009

[Abstract](1487)

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In order to solve the problem that system performances are impacted by increased train headway in the station area in an urban rail transit system, the existing algorithms for train headway in a CBTC (communication based train control) system were analyzed, and a headway optimization method was proposed based on the platform speed restriction and the speed-restriction-area parameter adjustment. With this method, an optimized train headway can be obtained by simulation of the relationship among platform speed restriction setting, train headway and travel speed. This method was simulated and tested on the CBTC simulation and performance analysis system developed by Southwest Jiaotong University. The process to optimize a train headway from 96 to 90 s in the test scenario was described. The result shows that the proposed method can optimize the headway in the critical area(s) of a CBTC system to improve the whole system performances.

Improved Electromagnetic Rail Launcher

JIANG Qi-Long, FU Lei

2011, 24(4): 586-591. doi: 10.3969/j.issn.0258-2724.2011.04.010

[Abstract](1429)

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To simplify the system configuration and improve the utilization of energy, the distributed-energy-storage rail launcher and the segmented rail launcher were analyzed and compared based on the basic principle of rail launcher. An improved electromagnetic rail launcher was proposed and simulation analyses for the improved rail launcher were made. In this improved rail launcher, 3D arrangement rail, less circuit switches and a new connection mode of the rail and the source are used. The results show that the improved electromagnetic rail launcher has not only high power efficiency, being 3 times that of a conventional rail launcher, but a small volume of the energy storage module.

Startup Capability of Boost DC/DC Converter

XIANG Gan-Yin, FENG Quan-Yuan

2011, 24(4): 591-597. doi: 10.3969/j.issn.0258-2724.2011.04.011

[Abstract](1047)

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An analytical model was proposed to calculate the minimum startup voltage of a boost DC/DC converter under a constant current load. The factors, such as the current load, the parasitic parameters, the saturation current and on-resistance of the power switch, the switching frequency, and the minimum startup voltage, etc., which affect the startup capability of the boost DC/DC converter were analyzed with a steady-state analysis method. The model was applied to the design of a boost DC/DC converter with a 0.6 μm CMOS process, and the maximum error of the minimum startup voltage calculated by the proposed model was 4.5% compared with that by the HSPICE simulator

CoarseSignalProcessingforACPowerSmartSensor

CHE Chang, HU Dan

2011, 24(4): 598-603. doi: 10.3969/j.issn.0258-2724.2011.04.012

[Abstract](1137)

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In order to improve the testing precision and real-time performance of the AC electrical power performance index, the coarse signal processing approach of AC power intelligent sensor was studied based on the theory of correlation analysis method and the least-squares method. The least-squares characteristic parameters method was used to estimate the initial sample points of AC voltage and AC current, and the electrical power parameters were obtained. The formulas of calculating quantity and computation complexity were discussed by comparing the least-squares characteristic parameters method with the correlation analysis method.The results show that when the noise signal amplitude is permitted from 3% to 12%, the proposed method can reduce the processing time by 49.4% and decrease the testing error by 2/3 ,and the requirement for the signal-to-noise ratio of the system can also be reduced as opposed to the traditional method.

New Estimation Method for Harmonic and Inter-Harmonic Parameters

LIU Ya-Mei, YANG Hong-Geng, MA Chao

2011, 24(4): 604-610. doi: 10.3969/j.issn.0258-2724.2011.04.013

[Abstract](1041)

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In order to analyze the effect of noise signals on the estimation of harmonic and inter-harmonic parameters, a new method was proposed on the basis of the essential property of noise information and the several useful strategies including the modern cross-spectrum, total least square, ESPRIT (estimation of signal parameters via rotational invariance) and improved Prony techniques. In this method, the cross-spectrum technique is used to deal with the cross-correlation matrix of different sampled signal sequences, and signal and noise subspaces are identified validly with the help of the independent principle of white noise at different times. And then the frequencies of signal components can be extracted directly by combining the total least square technique with the ESPRIT technique. Finally, based on the estimated frequency of every signal component and the characteristic of zero average value of noise signals, the magnitude and initial phase of the signal components are obtained by using the improved Prony technique. The results show that conditioned upon low signal-to-noise ratio, the proposed method can distinguish more sub-signals and the relative errors of frequencies are less than 0.4% with merely time consumption of 0.058 s, characterizing a high estimation accuracy and efficiency.

ANFIS-Based Fault Classification Approach for UHV Transmission Lines

LIN Sheng, HE Zheng-You, CHEN Shuang, QIAN Qing-Quan

2011, 24(4): 611-619. doi: 10.3969/j.issn.0258-2724.2011.04.014

[Abstract](1188)

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A novel fault type classification approach for ultra-high voltage (UHV) transmission lines was proposed based on the adaptive-network-based fuzzy inference system (ANFIS) to distinguish the ten common fault types, including single line to ground faults, line to line to ground faults, line to line faults, and three-phase fault. In this approach, the standard deviation and inter-quartile range of fault components of one cycle post-fault-current are taken as the characteristic quantities of fault classification. The influence of noise and harmonic on the characteristic quantities was analyzed. A fault classification model based on the ANFIS was established. A large number of simulations were carried out in PSCAD/EMTDC (power systems computer aided design/electromagnetic transients including direct current). The results indicate that the proposed approach is capable to identify fault types fast with a high accuracy up to 99.5%. Furthermore, the approach is insensitive to different fault initial angles, fault distances and fault resistances and has a good adaptability for different noise levels, harmonics, transform characteristics of current transformer (CT) and sampling frequencies.

Directional Reconstruction of Super Resolution Image by Magnifying Curvelet Basis

HAN Zhi-Wei, LIU Zhi-Gang, ZHAO Fei

2011, 24(4): 620-625. doi: 10.3969/j.issn.0258-2724.2011.04.015

[Abstract](1052)

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A super-resolution image reconstruction algorithm was proposed using the 2nd generation curvelet to reduce the edge blur caused by traditional algorithms. In the proposed algorithm, the original image is decomposed into j scales using curvelet. The curvelet coefficients in the j scales of the zoomed-in image are obtained by utilizing the proportionality of curvelet bases between adjacent scales, and the curvelet coefficients in the (j+1)th scale are determined by utilizing the spatial template of curvelet coefficients with the largest scale number. All the curvelet coefficients are processed with a nonlinear function to enhance image quality.The zoomed-in image with fine edges is finally created through curvelet reconstruction because of the good directional characteristic of curvelet. Experiments on two benchmarking images shown that, the proposed algorithm could preserve more image features and edge sharpness, and the peak signal to noise ratios (PSNRs) for the two images increased by 2.2 and 0.6 dB, respectively, compared with those obtained with a traditional interpolation algorithm.

Adaptive Technology for Vehicles Tracking Based on Intelligent Agent

QU Ju-Bao

2011, 24(4): 626-632. doi: 10.3969/j.issn.0258-2724.2011.04.016

[Abstract](1251)

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To study the problem of detecting and tracking fast-moving vehicles in complex circumstances, an adaptive algorithm for image segmentation and filtering was proposed using intelligent Agent based on knowledge database, and an adaptive background model was built through the dynamic matrix of accumulated frame differences. In the tracking process, an improved SSD (sum of squared differences) algorithm was designed to forecast the initial iteration points. According to the Jensen inequality, a MeanShift algorithm for iterative updating of the adaptive kernel-bandwidth was derived to achieve the adaptive intelligent tracking of moving vehicles in videos. The Experimental results shows that the algorithm can track the moving targets in videos effectively and accurately, and has a strong adaptive ability. Compared with other existing algorithms, the tracking error is reduced by 54.4%, and the average tracking time is extended by 41.3%.

Mixed Distribution Model of Vehicle Headway

TAO Peng-Fei, WANG Dian-Hai, JIN Cheng

2011, 24(4): 633-638. doi: 10.3969/j.issn.0258-2724.2011.04.017

[Abstract](1147)

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For describing the distribution characteristics of headway, driving behaviors are classified into car-following state and free driving state by reference to the two-fluid theory. After analysis of their operation features, a mixed distribution model that can describe the headway distribution of both the two driving states was built. The model parameters were determined by expectation maximization (EM) algorithm using the measured data. Then, the differences between the statistical characteristics of the driving behaviors in up-stream section, downstream section and different lanes were analyzed and verified through a case study. The results show that the mixed distribution model can pass the chi-square test in all road situations. Compared with the negative exponential distribution, Erlang distribution, and M3 distribution, the mixed distribution model can improve the fitting accuracy of simulation by more than 10%, and obtain a more close result to the measured data in calculating the traffic capacity of an expressway on-ramp.

Estimation Models for Average Speed of Traffic Flow Based on GPS Data of Taxi

JIANG Gui-Yan, CHANG An-De, LI Qi, YI Feng

2011, 24(4): 638-644. doi: 10.3969/j.issn.0258-2724.2011.04.018

[Abstract](1278)

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The existing average speed estimation models based on GPS (global positioning system) data of taxis are not applicable where high precision and low cost are of necessities. Two traditional models, namely a time integral model and a time interpolation model, based on the GPS data of taxis were modified, and the two modified models were combined to form a hybrid model. The three new models were verified using GPS data of taxis obtained from a part of road network of a large city. The results shown that the estimating precisions of the two modified models increased by 1.5% and 19.7%, respectively, compared with the original time integral model and time interpolation model, and those of the hybrid model by 2.8% and 8.8%, respectively, compared with the two modified models

Efficient Route Plan Algorithm Based on Multi-level Road Network Strategy

ZHONG Hui-Ling, ZHANG Meng, SHI Yong-Jiang, CAI Wen-Hua

2011, 24(4): 645-650. doi: 10.3969/j.issn.0258-2724.2011.04.019

[Abstract](1254)

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In order to overcome the shortcoming of route plan algorithms' inefficiency caused by an oversized road network, a new route plan algorithm, hierarchy A* algorithm, was proposed. The hierarchy A* algorithm is characterized by the multi-level road network decomposition pre-processing, the goal-directed strategy, the bidirectional strategy and the improved data structure strategy. The experimental result shows that compared with the A* algorithm and the highway hierarchical algorithm, the proposed algorithm increases the computational efficiency by averages of 11.7 and 2.4 times respectively, reduces the search space by averages of 5.7 and 2.8 times， respectively, and has a stable search space and computational efficiency.

Simulation of Landscape Impact on Driving Safety on Road Bends in Mountain Area

YANG Zhi-Fa, SONG Yu-Lin, GUAN Xin, LI Shi-Wu

2011, 24(4): 651-656. doi: 10.3969/j.issn.0258-2724.2011.04.020

[Abstract](1468)

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A simulation process was built to address the impact of landscapes on driving safety on road bends in mountain area. In the simulation, the judgment method of transverse slide accidents of vehicles, the generation method of obstacles or other vehicles within the front view of a driver, the calculation method of the sight distance of the driver, and the judgment method of the vehicle safety state are discussed in detail. Then, a simulation program written with VB language was used to analyze the impact of vehicle speed, bend radius and landscape position on the safety of vehicles. The results show that the risk probability of vehicles is reduced by about 58% on a large-radius bend than that on a small-radius bend when the two landscapes have the same distance from roadside and the road design speed is 60 km/h. With the same bend radius, the risk probability of vehicles in case of high road design speed was smaller than that in case of low one; for example, the risk probability is reduced by about 33% when the road design speed is increased from 80 to 60 km/h on a medium-radius bend.

Conditional Bus Signal Priority Strategies Considering Saturation Degree Restriction at Isolated Junction

BIE Yi-Ming, WANG Dian-Hai, SONG Xian-Min, GENG Yan

2011, 24(4): 657-661. doi: 10.3969/j.issn.0258-2724.2011.04.021

[Abstract](1093)

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To reduce the negative effect on general traffic caused by bus signal priority (BSP), a conditional priority methodology that considers the saturation degree restriction in the premise that no traffic congestion occurs at the intersection was brought forward, and two bus signal priority strategies, with or without green time compensation to non-priority phase, were established. The two strategies were tested in the VISSIM environment and compared with non-priority strategy and unconditional BSP strategy. The results show that the two strategies proposed outperform the non-priority strategy by 22.9% and 15.1%, respectively, in reducing the average bus delay in all scenarios, and outperform the unconditional BSP strategy by 10.7% and 16.5%, respectively, in reducing the increase of average vehicle delay in the scenarios with high bus frequency or high saturation degree

Avoidance Strategy for Head-on Conflict on Taxiway Based on Supervisory Control Theory of DES

ZHU Xinping, TANG Xinmin, HAN Songchen

2011, 24(4): 664-670. doi: 10.3969/j.issn.0258-2724.2011.04.022

[Abstract](1243)

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A closed loop control approach was proposed to overcome the shortcomings of open loop control that can not tackle stochastic events in airport surface operations. A control strategy for head-on conflict on taxiway in an airport equipped with an A-SMGCS (advanced surface movement guidance and control system) was investigated based on the supervisory control theory of DES (discrete event systems). A controlled Petri net model for the taxiway layout was established, which maps the set of places to the set of taxiing routes. The model was simplified using the known taxiing routes sequences of aircrafts. The sufficient and necessary conditions to avoid head-on conflict on taxiway were determined with the loops and loop chain being considered. Conflict avoidance strategies and the corresponding algorithm for decision-making were presented. Simulation demonstrated that the proposed strategy could identify and avoid head-on conflict on taxiway in real time by monitoring the surface operations.

Spray Characteristics of High-Pressure Mist Nozzle of Lubrication Device for Space Mechanisms

SHENG Mingwei, CHEN Weishan, LIU Junkao

2011, 24(4): 671-675. doi: 10.3969/j.issn.0258-2724.2011.04.023

[Abstract](969)

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To solve the lubricating failure of spacecrafts in orbit for lack of lubrication, a high-pressure mist nozzle was applied to the spatial lubrication field. A gas-liquid two-phase flow model for direct mist nozzles was established, and the mist flow generating process was simulated using the software of computational fluid dynamic technology CFD-ACE+2009. On this basis, both the lubricant flow velocity and pressure distribution near the nozzle were investigated. By comparison of two high-viscosity fluids, NYE 2001 and Krytox 143AB, with diesel oil in numerical experiments, the effects of fluid physical parameters on pressure propagation and flow velocity variation were analyzed. The simulation results show that the high viscosity of aerospace lubricant NYE 2001 would inhibit the pressure transfer in the mist nozzle severely; for instance, the pressure decreased from 1.5 MPa at the inlet to 0.42 MPa at the end of the 1 mm long nozzle, with a declining rate of 97.2%. Therefore, overhigh viscosity of liquid and overlong nozzle are unfavorable to droplets spray.

High-Accuracy Cooperative Positioning Algorithm in Multipath Environment

LIU Lin, FAN Pingzhi

2011, 24(4): 676-680. doi: 10.3969/j.issn.0258-2724.2011.04.024

[Abstract](1109)

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In order to protect location estimates from NLOS (non-line-of-sight) error influence, a high-accuracy cooperative positioning algorithm was proposed. In this algorithm the cooperative information between MSs (mobile stations) is used to enhance the location accuracy, and the relationship between measured TOA (time of arrival) and SF (sentinel function) defined by GIS (geographic information system) is utilized to identify NLOS. The detailed performance analysis of the algorithm was given. The simulation results show that under a multipath environment, the proposed algorithm has a significantly high location accuracy compared with the existing algorithm. The probability of location error less than 90 m is enhanced from 53% to 98% under the condition that five MSs in eight cooperative MSs are under an LOS (line of sight) environment.

New Fusion Estimation Algorithm for Systematic Errors of Multiple Dissimilar Sensors

SONG Qiang, HE You, XIONG Wei

2011, 24(4): 681-687. doi: 10.3969/j.issn.0258-2724.2011.04.025

[Abstract](1361)

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In order to solve the problem of systematic error estimation in a multiple dissimilar sensor network composed of passive sensors with DOA (direction of arrival) and TOA (time of arrival) measurements and active sensors, a new fusion estimation algorithm for systematic errors was proposed. With this algorithm, real-time estimation of the systematic errors of each sensor combination can be achieved through combining the active and passive sensors in pairs and establishing the systematic error model of dissimilar sensors. Then, the entire fusion estimation of the systematic errors of dissimilar sensors may be obtained through founding a multiple sensor fusion estimation structure and doing fusion and feedback of systematic error estimation for each sensor combination. The Monte-Carlo simulation result shows that the proposed algorithm can estimate the systematic errors effectively and is of engineering application value.

Multi-objective Optimization of Cross-Docking Logistics System under Stochastic Demand

HU Lu, PENG Bo, JIANG Yangsheng, ZHANG Gai

2011, 24(4): 688-694. doi: 10.3969/j.issn.0258-2724.2011.04.026

[Abstract](1453)

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In order to enhance the adaptivity of cross-docking logistics (CDL) to stochastic market demand, a multi-objective stochastic programming model was established. Taking both local and global interests into account and considering the factors such as random demand, inventory, distribution, and original orders, This model aims at improving the confidence level of final orders to meet the stochastic demand, increasing the vehicle loading rate, and reducing the total operation cost, and To solve the model, a multi-objective fitness function was constructed and normalized, and an adaptive genetic algorithm was designed. The result of a case study shows that, compared with the original orders, the final orders dealt with by this model can increase the confidence level meeting stochastic demand and vehicle loading rate by 3.59% and 12.71%, respectively, and reduce the average total cost per day by 631 845 yuan, a decline of 13.73%.

Experimental Study on Safe Driving Based on Electroencephalography

OU Jushang

2011, 24(4): 695-700. doi: 10.3969/j.issn.0258-2724.2011.04.027

[Abstract](1163)

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In order to study the effects of alcohol drinking on electroencephalography (EEG) during driving, a system of indicators for EEG analysis were set up based on the real-time EEG data of drivers collected by a neuroscan EEG system under virtual scenes made of sharp curves, emergency stop belts, obstacle zones and straight line segments. After fast Fourier transform, the mean powers of delta wave (δ), theta wave (θ), alpha wave (α), middle fast wave, beta wave (β), and gama wave (γ) were calculated, and the proportion of the power in each frequency range to the whole frequency range was obtained. Then, the differences of the combined indicator (α+θ)/β were compared between drunk driving and non-drunk driving, and all the indicators were analyzed by the paired sample t-test. The results show that alcohol drinking affects significantly the theta wave, alpha wave, and gama wave, with t-test values being less than 0.01; but does not affect significantly the rest of EEGs, with t-test values being more than 0.05. Among the three parameters affected significantly, only the difference of gama wave before and after drinking reduces gradually with the blood alcohol concentration (BAC) decreasing. When the BAC dropped to 40.5 mg/100 ml, the difference of gama wave was 1.12%.

Application of Remote Sensing to Land Cover Change Induced by Nargis Hurricane in Myanmar

CHEN Xiao-Yong, LIU Bo, AungKyawTUN

2011, 24(4): 701-705. doi: 10.3969/j.issn.0258-2724.2011.04.028

[Abstract](1204)

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In order to investigate the effects of the Nargis hurricane on the Ayeyarwady Delta in Myanmar, the ISODATA (iterative self-organizing data analysis techniques algorithm) unsupervised classification method and the Bayesian maximum-likelihood supervised-classification method were used to classify the land cover of the study area based on Myanmar ALOS/AVNIR-2 remote sensing data, and the quantitative changes of land cover in the Ayeyarwady Delta before and after the Nargis hurricane were obtained. In addition, the relationships between the Nargis hurricane disaster and the area and density of mangrove forests were investigated quantitatively. The research result shows that a mangrove forest with a large area and high density has a great effect to decrease a hurricane disaster such as the Nargis hurricane disaster.

Screening Functional Strains and Constructing Complex Microbial System for Accelerating Stabilization of Landfill

QIU Zhong-Peng, LIU Yuan-Yue, WANG Qian, TANG Jian, TONG Fei, ZHOU Li-Ping

2011, 24(4): 706-711. doi: 10.3969/j.issn.0258-2724.2011.04.029

[Abstract](1179)

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For accelerating the stabilization of landfill, functional strains were screened and sub-cultured repeatedly with traditional microbiological methods in surroundings. Then the screened strains were grouped and coded from I# to VII# based on the different functions of the strains. The compound flora used to accelerate the stabilization of landfill was constructed by analyzing zymogenic capacities and the effects on stability indices. The results show that the functional strains with stable performance includes 9 cellulose bacteria, 8 COD（chemical oxygen demand) degrading bacteria, and 7 bioflocculant-producing strains. The functional flora coded VII#, composed of all the above strains, has the greatest abilities of generating enzymes, which can improve the biodegradation of refuse effectively and hence accelerate the stabilization of landfill. Compared with those of the control group, the organic biodegradation rates, HP (humic acid percentage), and sedimentation of leachate treated with the flora group coded VII# are increased by 26.23%, 9.18%, and 10.01%, respectively.

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2011 Vol. 24, No. 4