西南交通大学学报

Integrated Wind Speed Standard for Long-Span Bridges over Deep-Cutting Gorge

LI Yongle, TANG Kang, CAI Xiantang, LIAO Haili

2010, 23(2): 167-173. doi: 10. 3969/ j. issn. 0258-2724.

[Abstract](1903)

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Abstract:
To consider the difference of wind characteristics for different members of a long-span bridge in complex terrains, the basic wind speed for the region was calculated on the basis of the statistical analysis of historical observation records of wind speed from meteorological stations involved. From the simultaneous observation data from the meteorological stations and observation points in a bridge site, the revision relationship between wind speeds at the bridge site and at the meteorological stations was established by the analysis of correlativity. By considering the terrain feature of the bridge site and combining the results of computational fluid dynamics analysis, the design wind speeds were determined for bridge deck and each pylon, and the concept of integrated wind speed standard was presented. The results show that the integrated wind speed standard instead of the uniform wind speed standard takes the differences among wind characteristics for bridge deck and each pylon into account, and it is fit for long-span bridges over a deep-cutting gorge.

Safety Appraisement of Existing Structures Based on Pushover Method

PAN Yi, 2, YANG Cheng, ZHAO Shichun, 2　LIN Yongjun, DAI Jie

2010, 23(2): 174-178. doi: 10. 3969/ j. issn. 0258-2724.

[Abstract](1421)

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In order to evaluate the safety of existing structures accurately, based on the method of performance-based seismic design and by combining with the national codes Standard for Appraiser of Reliability of Civil Building and Criteria for the Classification of the Buildings'Seismic Damage Ranks, the pushover method was adopted to appraise the safety of existing structures. By taking a frame structure damaged in the Wenchuan earthquake in Dujiangyan City as an example, the safety and earthquake damage levels of the structure were appraised under a given earthquake action. The research shows that the analysis result is dovetailed basically with the real earthquake damage, and the safety of existing structures can be assessed effectively through the pushover method.

Numerical Simulation of Aseismatic Behavior of Retrofitted Masonry-Timber Structure of Jushi Building on Qingcheng Mountain

YU Zhixiang, ZHAO Shichun, WU Hao

2010, 23(2): 179-185. doi: 10. 3969/ j. issn. 0258-2724.

[Abstract](1538)

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An investigation was carried out on the Jushi building being retrofitted in the Shangqing Temple on the Qingcheng Mountain in order to research the retrofitting measures of religious buildings. The FEM (finite element method) was adopted to set up the numerical model of this ancient building by taking the nonlinear boundary into account. The self-vibrating behavior of the structure was analyzed to prove the validity of the numerical model. The deformation, base shear and internal force of its members before and after retrofitting were investigated by the transient dynamic analysis. The research results indicate that a flexible boundary can form a rigid-flexible system, harmonize the deformation of the two types of members well and improve the aseismatic behavior significantly

Remote Sensing Dynamic Monitoring and Driving Force Analysis of Land Use / Cover Changes in Chengdu

YANG Wunian, 2, LIU Enqin, CHEN Ning, LIAO Chonggao, 3

2010, 23(2): 185-190. doi: 10. 3969/ j. issn. 0258-2724.

[Abstract](1504)

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To explore variation in the structure of land use/ land cover in Chengdu City due to the rapid development of urban construction in the past approximate 30 years, changes of its land use were dynamically monitored with its Landsat MSS and TM satellite remote sensing images in the years 1978 1992, 2000 and 2005, and a land use database for different times was established by the processing of the remote sensing images and the extraction and interpretation of information. With the help of support of GIS (geographic information system) spatial analysis function, the information of land use changes in Chengdu in the recent 28 years was extracted. The characteristics in the structure of its land use changes in the recent 28 years were analyzed quantitatively, and the driving forces of land use changes in Chengdu were discussed from natural and human factors. The research results provides a scientific basis for the relevant departments of the government to improve their acts scientifically and rationally in urban and rural planning, management and decision-making.

Random Vibration Property of High-Speed Railway Vehicle in Passenger Dedicated Line

LI Bin, 2, LIU Xueyi

2010, 23(2): 191-196. doi: 10. 3969/ j. issn. 0258-2724.

[Abstract](1645)

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To investigate the vibration regularity of a railway vehicle under track irregularity in a passenger dedicated line ( PDL), a concept of artificial short wave of track irregularity was put forward, and a sample of the artificial short wave was given. Vertical irregularity and cross-level irregularity were considered synchronously. By combining the sample of artificial short wave and the sample of low disturbance irregularity of high-speed railway in German, a simulated sample of track irregularity was established to analyze the railway vehicle vibration laws in a vehicle-track vibration system. The random vibration properties of all vehicle parts and their variation regularities with train speed were investigated. The research results show that the random vibration responses of all parts of a railway vehicle in PDL increase with the increase of train speed. The increase of wheelset acceleration is much more obvious than bogie and body accelerations and wheel/ track force, and the increase of displacement is limited.

Seismic Deformation and Failure Modes and Mechanism of Soil Mass

WANG Jian, YAO Lingkan, JIANG Liangwei

2010, 23(2): 196-202. doi: 10. 3969/ j. issn. 0258-2724.

[Abstract](1479)

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To study the seismic deformation effect of soil mass, a field investigation on slopes reinforced by shotcrete-bolt system and road embankments along Dujiangyan to Yingxiu highway was conducted. The investigation shows that the seismic deformation and failure modes of soil mass laterally unrestrained as slopes and road embankments are characterized by subsidences and lateral landslides, while soil mass laterally restrained by retaining wall is characterized by ubsidences and concavo- convex deformation, i. e. , alternative settling and bulging deformation. Seismic subsidence rate and concave-convex amplitude rise with the increase of seismic intensity and obey a normal distribution. Seismic damage level of the upper slope is affected by plane alignment of highway. The slope damage of a convex-curve section is more serious than a concave-curve section, and the damage of a linear section is most light. Shaking table tests of soil mass models laterally unrestrained or laterally bounded were conducted, and the results are consistent with the field investigation ones. The threshold of peak ground acceleration from subsidence to concave-convex deformation is approximate 0. 6 times of gravity acceleration.

Effect of Unsupported Sleepers on Sleeper Dynamic Response

ZHANG Jian, WU Changhua, XIAO Xinbiao, WEN Zefeng, JIN Xuesong

2010, 23(2): 203-208. doi: 10. 3969/ j. issn. 0258-2724.

[Abstract](1455)

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A vertical vehicle-track coupling dynamic model was established to analyze the effect of different unsupported sleeper situations on the sleeper dynamic response in the vertical direction. In the model, the vehicle is treated as a multi-rigid-body system, and the rails are assumed to be Euler beams supported by the discrete sleepers resting on an elastic foundation. The non-linear dynamic equations of the vehicle-track coupling model are solved with the explicit integration method. Numerical results indicate that the partially or fully unsupported states of sleeper changed the location of the sleeper maximum moment greatly; more unsupported sleepers would incur bigger bending moment in the sleepers; and the fully unsupported sleepers have a great influence on the dynamic behavior of the sleepers adjacent to the section of the unsupported sleepers

Influences of Traction Motor Vibration on Bogie Frame Fatigue Strength

AN Qi, LI Fu, FU Maohai

2010, 23(2): 209-212. doi: 10. 3969/ j. issn. 0258-2724.

[Abstract](1831)

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To analysis the causes of fatigue failure on the area around the traction motor seat of metro vehicle power bogie frames, the fatigue strength of the frame was calculated by using FEM. The calculated results show that the stresses on the area around the traction motor seat are mainly influenced by the vertical vibrations of traction motor. Increases in vertical vibration acceleration of the traction motor causes an increase in stress amplitudes of the dangerous nodes although it basically has no effect on the average stress of the node. When the vertical vibration acceleration of the traction motor increases from 1 g to 10 g, the stress amplitudes increases by about 1. 5 times, and the related safety factors decrease from over 2. 68 down to about 1. 00. The safety factors do not change with horizontal vibrations when they are within the ranges specified by specifications.

Experimental Study on Spray Characteristics and Fire Suppression Performance of Pressure Swirl Nozzle

LIU Zhichao, 2, YU Minggao, ZHENG Ligang

2010, 23(2): 213-217. doi: 10. 3969/ j. issn. 0258-2724.

[Abstract](962)

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A pressure swirl nozzle for water mist fire suppression was developed and experimentally studied to optimize the parameters of the nozzle. The influences of the design parameters, the operating pressure, and the additive to plain water on spray characteristics were also investigated. The results show that the Sauter mean diameter (SMD) of droplets was decreased by 8% when the operating pressure was increased from 0. 5 to 1. 5 MPa; and that adding additive in water could decrease the SMD by about 1. 3% to 15%. What's more, the larger the SMD of mist droplets, the wider the range of droplet diameter distribution; and the trend that the volume fraction curve of droplet diameter shifts towards the large diameter direction was also found. The relationship between the mist velocity and the operating pressure was approximately a linear positive dependence. When the nozzle structure was not properly designed, the downstream distribution of the water mist flux would not be uniform, which is disadvantageous to fire suppression.

CNG Direct Injection Engine Control Based on Rapid Control Prototype Technique

PENG Yiqiang, LI Wei, 2, LI Jingbo

2010, 23(2): 218-221. doi: 10. 3969/ j. issn. 0258-2724.

[Abstract](972)

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To improve the performance of compressed natural gas (CNG) engines, CNG in-cylinder direct injection was implemented with a rapid control prototype ( RCP) technique. According to application requirements, the flow characteristics of the direct injector was tested, a gas supply system for the CNG direct injection engine was designed, and the control strategy for the CNG in-cylinder direct injection was made. The experiment results show that the output torque of the CNG in-cylinder direct injection engine could reach the output level of a gasoline engine of the same kind. At the rotational speed of 2 500 r/ min, the power loss of the CNG in-cylinder direct injection engine compared with the gasoline engine was only 0. 006%.

Theoretical Study on Real Tooth Surface of Non-backlash Double-Roller Enveloping Hourglass Worm

DENG Xing-Qiao, WANG Jin-Ge, ZHANG Jun-Fu, WU Jiang

2010, 23(2): 222-226. doi: 10. 3969/ j. issn. 0258-2724.

[Abstract](924)

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To acquire the real tooth surface of the non-backlash double-roller enveloping hourglass worm, a mathematic model for the non-backlash double-roller enveloping hourglass worm gearing was established according to the space meshing theory, in which the contact helix line equation of the worm gearing was derived. On the basis of the contact helix line equation, Pro/ E software was used to produce the real tooth surface of the non-backlash double-roller enveloping hourglass worm. Then, the contact helix lines acquired by Matlab software were compared with the tooth surface produced by the Pro/ E software, to analyze the influence of the number of contact helix lines on the tooth surface fitting precision. The results show that the fitting precision of the tooth surface is determined by the number of contact helix lines, and that the tooth surface acquired by the proposed method can exactly reflect the real meshing tooth surface, with the fitting precision being 0. 001 00 mm, when the number of helix lines is nine.

Effects of Si Concentration on Microstructure of Si Steel Thin Strips Prepared by Twin Roll Continuous Casting

YI Yu, ZHOU Zehua, WANG Zehua, JIANG Shaoqun

2010, 23(2): 227-232. doi: 10. 3969/ j. issn. 0258-2724.

[Abstract](947)

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The effects of Si concentration on microstructure of Si steel thin strips prepared by twin roll continuous casting were investigated with optical microscopy, transmission electron microscopy and energy spectrum analysis to provide a theoretical and technological reference for post treatment procedure of the steel. The Si steel under investigation has Si concentration of 0. 5%, 1. 0%, 3. 0%, 4. 5% and 6. 5% (mass fraction), respectively. The results show that Si concentration strongly affects grain sizes, morphology of grain boundaries and dislocations of the strips. When Si concentration is 3. 0% to 4. 5% (mass fraction), the strips have large grains, pure grain boundaries, less dislocations and slight segregation.

Detection of Backside Vehicle on Freeway in Daytime on Freeway in the Daytime

JIN Lisheng, JIA Min, SUN Yuqin, HOU Haijing

2010, 23(2): 231-237. doi: 10. 3969/ j. issn. 0258-2724.

[Abstract](1114)

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A method for detection of backside vehicle on freeway in daytime was proposed to help the driver check the existence of backside vehicles in the target lane, especially those in the blind zones, and to reduce traffic accidents during lane changing. The road images are classified into two categories: taken under normal and weak illumination conditions according to their gray values. The possible backside vehicle is recognized if there is a sudden change in gray values within the area in the lanes of both sides because the gray values of vehicle shadows are smaller than the average gray value of the road surface. The existence of backside vehicle is confirmed by comparison between the ratios of windshield sizes extracted from the images with those in a list of the known vehicles after egmentations with different thresholds for normal and weak illumination conditions, denoising, and boundary extraction. Experimental results show that the proposed algorithm has good reliability and robustness.

New Prediction Method of Operating Speed and Its Application to Highway Alignment Evaluation

XU Jin, PENG Qiyuan, SHAO Yiming, ZHAO Jun

2010, 23(2): 238-248. doi: 10. 3969/ j. issn. 0258-2724.

[Abstract](1135)

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To predict operating speed in highway design phase and ensure the coordination ofalignment elements, models of lateral to lerated acceleration, longitudinal acceleration and deceleration, brake attenuation, environment speed concerned highway alignment were developed to determine the desired speed along the highway. A roadway-driver-vehicle-environment system (RDVES) was established to simulate vehicle models driving on 3D road-surface. With the RDVES, the operating speed of test roads was obtained and analyzed. The results show that (1) similar circle radii and tangent length along roadways was the best solution to avoid speed fluctuation, and shorter tangent should be adopted; (2) the acceleration distance of a vehicle when exiting curves was usually larger than the brake distance when impending curves, and both were much larger than the spiral length; (3) interchange of revolution and translational energy of driving vehicle will cause speed change when driving on mountainous roads containing sharp curves; (4) coordination of highway alignment by the operating speed method would be not applicable for evaluation of fourth-class grade highways; (5) the effect of corner cutting increases as deflection angle decreases, and hence the operating speed on the curves would be higher.

Auction Algorithm for Shortest Paths in Road Networks Considering Delays for Intersection Movements

DU Mu-Jing, CHENG Lin

2010, 23(2): 249-254. doi: 10. 3969/ j. issn. 025-2724. 2

[Abstract](1227)

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In order to overcome the deficiencies that traditional algorithms for solving the shortest path problems spend large computing costs and are unable to consider the turning delays at intersections, an improved auction algorithm that can directly find out the shortest path between two nodes in restricted networks was proposed. In this algorithm, the price vector was expanded from one dimension to two to avoid being overwritten when it represents different turning movements. A memory-saving and easy-searched data structure was designed to describe intersection movements accurately. The proposed algorithm and Dijkstra's algorithm were implemented to solve the single-origin/ single-destination shortest path problems for comparison in random networks of various scales and densities. The results show that the running time of the proposed algorithm is approximately 30% of that of Dijkstra's algorithm in high density networks with 5 000 nodes and 20 000 links, and it can accurately solve for the shortest path in restricted networks. This algorithm also inherits the characteristic from the original auction algorithm in the performance of parallel computing

Reserve Capacity Model for Urban Road Network with Variable Lanes

ZHANG Feng, LI Wen-Quan, CHANG Yu-Lin

2010, 23(2): 255-260. doi: 10. 3969/ j. issn. 0258-2724.

[Abstract](1184)

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To study the influence of lane allocation on road network capacity, a bi-level programming model of network reserve capacity was established by allocating lane numbers in both directions of two-way roads and setting traffic signal-timing parameters at individual intersections. The upper-level problem is the integrated optimization of lane allocating and signal timing to maximize the reserve capacity of road network. The lower-levelproblem represents a network equilibrium model, which predicts the reaction (i. e. , route choice behaviors) of drivers to any given lane allocation and signal control pattern. Then, a heuristic solution algorithm based on sensitivity analysis was proposed to solve the bi-level programming model. The numerical test results show that, compared with the traditional model, the bi-level model proposed in this paper can increase network reserve capacity by 32%, because it can regulate road impedance to make the distribution of traffic flows more balanced in all lanes.

Robust Optimization of Aircraft Arrival and Departure Flow Allocation Based on Dynamic Capacity

YANG Chang-Wen, HU Meng-Hua

2010, 23(2): 261-267. doi: 10. 3969/ j. issn. 0258-2724.

[Abstract](1562)

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To optimize the allocation of aircraft arrival and departure flow under dynamic capacity of airports and fixes, an absolute robust optimization model, a deviation robust optimization model, and a relative robust optimization model were built, where the objective function is to minimize the total cost of delayed flights. Then, a solution process based on predatory search algorithm was developed to solve he robust optimization problems. A case study regarding the operation of one of Chinese airports was performed to verify the models. The simulation results show that the robust optimal solutions produced from these models could effectively avoid risks on the basis of different decision preferences in actual operations; compared with the optimal solution under the capacity of terminal area with common conditions, the strategy of deviation robust optimization could reduce the delay cost by 8. 2%, and the strategy of relative robust optimization could reduce the delay cost by 7. 8%.

Two-Stage FFH / MFSK System Based on Frequency Hopping Sequence with No-Hit Zone

YIE Wen-Xia, FAN Peng-Zhi, HAO Li

2010, 23(2): 268-273. doi: 10. 3969/ j. issn. 0258-2724.

[Abstract](1034)

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To improve system capacity, a two-stage FFH/ MFSK (fast frequency hopping/ multilevel frequency-shift-keying) system based on frequency hopping sequence with no-hit zone (NHZ), named as NHZ/ FFH system, was proposed. In this system, users are divided into a number of groups, and each group is assigned a unique NHZ FH ( frequency hopping) sequence. Because the cross-correlations of NHZ FH sequences are equal to zero within no-hit zone, the multiple-access interference (MAI) between users of different groups can be eliminated as long as their relative delays do not exceed the no-hit zone. Therefore, MAI is only imposed on users belonging to the same user group. Furthermore, the multiuser detection scheme used in an asynchronous system is utilized to improve the detection performance, and the size and complexity of the multiuser detector are only decided by the number of users within a group. Interference analysis and simulation were carried out based on the system model. The simulation results show that compared with the existing MS/ FFH system, the number of users supported by the proposed NHZ/ FFH system is great for the same BER (bit error rate) level under the same channel condition

Takagi-Sugeno Fuzzy State Observer for Induction Motor

JIANG Lin, 2, XIAO Jian, WANG Tao

2010, 23(2): 273-277. doi: 10. 3969/ j. issn. 0258-2724.

[Abstract](1072)

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To solve the instability problem of traditional adaptive flux observer for IM (induction motor) working at low speed generating mode, a new state observer was proposed based on T- (Takagi-Sugeno) fuzzy model. In the observer, the fifth-order nonlinear time-varying model for IM is used to observe magnetic flux and estimate speed. The fuzzy observer was designed by combining Lyapunov stability theory and linear matrix inequality technology, and was applied to estimate speed of sensorless IM drives. The simulation results indicate that the speed observation error is less than 1. 78%,and the IM drive is stable in a variety of operating conditions over the whole working speed range

SiC CMOS OPAMP High Temperature Model and Hspice Simulation

YANG Yin-Tang, LIU Li

2010, 23(2): 278-283. doi: 10. 3969/ j. issn. 0258-2724.

[Abstract](1161)

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The high temperature equivalent circuit of standard silicon carbide ( SiC) CMOS (complementary metal-oxide-semiconductor) OPAMP (operational amplifier) with PMOST (P-type metal-oxide-semiconductor transistor) as input was drawn and its Hspice simulation was conducted to provide a foundation to further develop SiC CMOS OPAMP with temperature stability. The simulation result shows that because a high interface trap exists, variation of threshold voltage with temperature is not linear as that of Si MOS devices, and effective channel mobility is not proportional to temperature to the minus 1. 5th power. Furthermore, a low effective channel mobility results in a low conductance, so SiC OPAMP has a lower open loop gain than that of Si counterpart with the same structure and size. Although standard OPAMP cell has a temperature stability to Si-based MOST, a further modify should be done to SiC-based MOST

Reliability and Power Consumption Optimization for SoC

ZHANG Xiao-Lin, YANG Gen-Qiang, ZHANG Yu-Ning

2010, 23(2): 284-289. doi: 10. 3969/ j. issn. 0258-2724.

[Abstract](1273)

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Tradeoff between the high reliability and low power consumption for SoC (system on a chip) was investigated. Based on the proposed reliability and power consumption characterization model, reliability-aware and low-power design was illustrated as a design methodology to balance reliability enhancement and power reduction. Reliability-aware dynamic voltage/ frequency scheduling (DVFS) algorithm was demonstrated as a case study of this new design methodology. The simulation demonstrates the effectiveness and feasibility of the methodology and obtains a significant improvement of 15. 99% in energy consumption at a cost of 5% reliability decrease.

Radar Emitter Signal Recognition Based on WRFCCF

YU Zhibin, JIN Weidong, CHEN Chunxia

2010, 23(2): 290-295. doi: 10. 3969/ j. issn. 0258-2724.

[Abstract](1215)

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In order to identify the advanced radar emitter signals (RES), an automatic recognition approach of signals was proposed. This approach is based on the cascade-feature of the wavelet ridge- frequency (WRF). The new wavelet atom and the detection strategy are used to extract the WRF feature of the RES, and the wavelet ridge-frequency cascade-feature (WRFCCF) is extracted to identify the RES. Simulation results show that the proposed approach can achieve a correct rate of above 95% even when the SNR ( signal-to-noise ratio) is as low as 5 dB. Compared with the traditional wavelet and the existing approaches, the proposed approach has a fine recognition effect.

Divisive Hierarchical Clustering Algorithm Based on Grey Relational Measure

CHEN Tao-Wei, JIN Wei-Dong, LI Jie

2010, 23(2): 296-301. doi: 10. 3969/ j. issn. 0258-2724.

[Abstract](1254)

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To estimate cluster number and achieve a better clustering performance, a divisive hierarchical clustering algorithm based on grey relational measure was proposed. In this algorithm, the grey relational measure is used to measure the degree of similarity between data sets. On the basis of the way of density-based extension, the algorithm divisively generates hierarchical partitions of data-set. And then the clustering validity index is defined based on the grey relational measure. The-partitions corresponding to the extremum of the validity index curve are used to estimate the number of-clusters finally. Computer simulation on real and synthesis data sets shows that compared with the FCM-(fuzzy C-means) algorithm, the proposed algorithm has a 3. 7% improvement in average clustering correct rate and is good for arbitrary-shaped clusters.

Key Search Quantum Circuit Design of AES Cipher

YE Feng, YUAN Jia-Bin

2010, 23(2): 302-307. doi: 10. 3969/ j. issn. 0258-2724.

[Abstract](1069)

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In order to verify the feasibility of applying the quantum search to the key search of block ciphers, a key search quantum circuit of AES (advanced encryption standard) cipher was designed, including KeyExpansion module, encryption module and comparison module, based on the analyses of its computation processes and computation modules needed to be achieved. The encryption module includes four sub-modules, i. e. , quantum AddRoundKey, SubBytes, ShiftRows and MixColumns. In order to reuse the working quantum bits, the reversible computation is used to eliminate the quantum entanglement effect, and different methods of the reversible computation are adopted to different tasks of the 4 sub-modules in the realization of the quantum encryption module so as to save computation time and quantum memory. The research shows that applying the quantum search scheme to the key search of block ciphers to save square root time is feasible

Alternative Ranking Based on Fuzzy Similarityin Group Decision-Making

GUO Qiang, GUO Yaohuang, GUO Chunxiang

2010, 23(2): 307-311. doi: 10. 3969/ j. issn. 0258-2724.

[Abstract](1206)

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It is difficult to rank alternatives in group decision-making because of multi-attributes,limitations to policy-makers in their understanding of matter under discussion, and contradiction in the decision-makers. To solve this problem, fuzzy similarity was introduced to measure the preference differences from the decision-makers, and their opinions were summed up using OWA ( ordered weighted averaging) operator. Alternative Ranking was realized by comparing the alternatives with virtual positive and negative ideal solutions. The procedure for the decision-making was presented

Decision Tree Construction Based on Cloud Transform and Rough Set Theory under Characteristic Relation

SONG Jing, CU Jian-Huai

2010, 23(2): 312-316. doi: 10. 3969/ j. issn. 0258-2724.

[Abstract](1112)

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A new algorithm, DTCCRSCR (decision tree construction based on cloud transform and rough set theory under characteristic relation), was proposed for mining classification knowledge from incomplete information systems. It utilizes cloud transform to discretize continuous data, and then the attribute with the smallest weighted mean roughness under the characteristic relation is selected as the current splitting node. Experimental results show that decision trees constructed by the DTCCRSCR have a simpler structure, a higher classification accuracy and more understandable rules than those based on the C5. 0 algorithm.

Characteristics of Heavy Metals in Semi-aerobic Landfill Leachate

YANG Qiao-Yan, LIU Dan, LI Qi-Ban, CHA Kun

2010, 23(2): 317-323. doi: 10. 3969/ j. issn. 0258-2724.

[Abstract](1138)

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To raise the removal rates of heavy metals in leachate, pilot-scale experiments of semi- aerobic landfill were carried out, the factors influencing the characteristics of heavy metals in semi- aerobic landfill leachate, such as pH value, ammonia nitrogen and dissolved oxygen (DO), were investigated. The results show that pH value and DO play an important role in the attenuation of heavy metals. When pH value is small, the concentration of heavy metals is great. The influence of DO is decided mainly by the states of heavy metals in waste. After 250 d, the removal rates of Cr, Ni and Pb are 76. 5%, 94. 3% and 91. 4% respectively.

Stream Line Optimization Model with Matching Degree between Logistics Supply and Demand as Objective Function

ZHANG Jin, WANG Kun

2010, 23(2): 324-330. doi: 10. 3969/ j. issn. 0258-2724.

[Abstract](2083)

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To reveal the basic laws and characteristics of logistics activities, a stream line network structure with multi-layer, multi-stage, and multi-attribute was proposed based on the reationship between logistics supply and demand, and the mathematical description was presented. Three kinds of degradation structures of industrial, trading and regional logistics activities were discussed. The matching degree was defined to describe the relationship between logistics supply and demand in terms of time, quantity and cost. A stream line optimization model was set up, in which the matching degree between supply and demand was taken as the objective function and the capacities and resources as the constraints.

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2010 Vol. 23, No. 2