西南交通大学学报

Effect of Coupler Compression Force on Locomotive Safety on Tangent Track

YANG Guang-Wu, XIAO Shou-Ne, MA Wei-Hua

2010, 23(5): 657-662. doi: 10. 3969/ j. issn. 0258-2724.

[Abstract](1747)

Abstract:
Equations of loads on the car-body were derived, and relations between yaw stiffness of the coupler and yaw angle of the car-body as well as compression forces were determined based on the car- body geometry and loads on the coupler and the car-body. The load equations were solved with a Newton iteration method to obtain the criterion for guaranteeing locomotive safety on tangent track. Theoretical analysis and dynamics simulation indicate that it is a necessity for the yaw stiffness of coupler to be greater than a critical value to prevent the wheel from flanging the track.

Influences of Relative Position between Turnout and Bridge on Coupled Vibration of Train-Turnout-Bridge System

QUAN Shunxi, WANG Ping, CHENG Rong

2010, 23(5): 663-668. doi: 10. 3969/ j. issn. 0258-2724.

[Abstract](1714)

Abstract:
In order to determine the reasonable relative position between turnout and bridge, a vibration analysis model for the coupled train-turnout-bridge system was built, and the numerical simulation method was applied to analyze the influences of the relative position between turnout and bridge on the dynamic characteristics of train, turnout, and bridge when No.18 single crossover turnout was located at a 6×32 m continuous beam bridge at train speed of 350 km/h. The results indicate that the relative position between turnout and bridge has little influence on the maximum dynamic wheel load, flange force, displacements of switch rail and nose rail, and running stability of trains, but has a significant influence on the maximum load reduction rate, derailment coefficient, dynamic stress of rail, and acceleration of bridge; and the reasonable relative position between turnout and bridge is that the frog should be located in the range of 1/8 to 1/4 of the third span in the train direction.

Mechanical Properties of Continuous-Slab-Track Welded Turnout on Bridge

QIAO Shenlu, GAO Liang, QU Cun, XIN Tao

2010, 23(5): 669-675. doi: 10. 3969/ j. issn. 0258-2724.

[Abstract](1228)

Abstract:
In order to study the mechanical properties of longitudinal connected ballastless welded turnouts on bridges, a longitudinal-transverse-vertical spatial coupling model was established according to the characteristics of the turnouts using finite element method. Taking the single crossover of No. 18 welded turnout for ballastless track laid on a bridge in passenger dedicated line as an example, the influences of some main factors, including stiffness of track plate/ seating plate, length of friction plate, and bridge type, on the mechanical properties of the longitudinal connected ballastless welded turnout on bridges were analyzed. The computational results show that the reduction of stiffness of track plate/ seating plate has little effect on the force and deformation of the track structure, but is favorable for the force of substructure, with the largest reduction of about 90%; lengthening the friction plate is helpful for controlling the force and deformation of the turnout, and can also decrease the force of substructure (for instance, the force acted on the end thorn was decreased by about 18% when the friction plate was lengthened from 50 to 100 m); and the longitudinal connected ballastless welded turnout should be laid on the continuous bridge.

Shakedown Limit Analysis for Plastic Deformation Failure of Gears

LIAO Haiping, 2, LIU Qiyue

2010, 23(5): 676-680. doi: 10. 3969/ j. issn. 0258-2724.

[Abstract](1018)

Abstract:
In order to study the influences of residual stresses on the plastic limit of gear material for optimal design of cylindrical spur gears, the elastic contact stress, residual stress, and elastic-plastic contact stress in gear engagement were analyzed using the Hertz contact theory and elastic-plastic contact models of gears in local coordinates. According to the third strength theory, the elastic limit of the gear material in the elastic state was derived to be about 1. 6 times its tensile and compressive yield strength. Considering the strengthening effect of residual stresses on the gear material, the gear elastic- plastic static shakedown limit was about 2. 3 times the tensile and compressive yield strength of the gear material according to the shakedown theory. When the static shakedown limit is used as the failure criterion of gear plastic deformation, the allowable stress of the gear material can be improved by about 50% over the elastic limit.

Effects of Refrigerant Charge on Performances of Transcritical CO2 Heat Pump Water Heater

JIN Dongxu, 2, KOYAMA Shigeru, XUE Jun, TAKATA Nobuo

2010, 23(5): 680-684. doi: 10. 3969/ j. issn. 0258-2724.

[Abstract](1032)

Abstract:
The performance parameters such as heating COP ( coefficient of performance ), compression ratio, suction and discharge pressures, and so on, of a transcritical CO2 heat pump water heater were experimentally investigated under various refrigerant charging conditions to study the effects of refrigerant charge on the heating COP. Experiments were conducted under the condition of constant heating capacity and compressor inlet superheat by simultaneous control of the compressor frequency and the pulse of electronic expansion valve. Experimental results showed that the compressor discharge pressure rose and the refrigerant outlet temperature from the gas cooler dropped as the refrigerant charge was increased, the suction pressure increased while the compression ratio and discharge temperature decreased as the inlet temperature of heat source fluid increased, and the maximum heating COP increased with an increase in heat source fluid inlet temperature. The maximum heating COP was 3. 25 at the heat source fluid inlet temperature of 15 'c, the compressor inlet superheat of 5 'c, and the optimum refrigerant charge of 1. 7 kg.

Intelligent Monitoring System for Screw Life Evaluation

GAO Hongli, LI Dengwan, XU Mingheng

2010, 23(5): 685-691. doi: 10.3969/j.issn.0258-2724.2010.05.006

[Abstract](1574)

Abstract:
The effects of rotating speed and load on screw life were investigated to study the performance degradation of screws of NC (numerical control) machine tools under different machining conditions. The real time data of vibration and cutting forces were collected. The key effects on the screw life were identified by analyses on time and frequency domains and wavelet analysis following filtering of the collected data with an empirical mode decomposition. A screw life prediction model was proposed using a multi-model fusion and a B-spline fuzzy neural network. Experimental results show that the maximal error of life prediction is 846 h, and the proposed system meet the need of active maintenance of screw.

Checking Calculation of Fatigue Strength for Cast Steel Joints of Offshore Tour Tower under Wave Loads

JIN Hui, 2, LI Jing, LI Aiqun

2010, 23(5): 692-697. doi: 10. 3969/ j. issn. 0258-2724.

[Abstract](1062)

Abstract:
In order to estimate the fatigue life of cast steel joints, by taking the steel tour tower structure on the offshore platform of Hangzhou Bay bridge as an example, a checking calculation method of fatigue strength for cast steel joints under wave loads was proposed. Using the statistical method, the wave loads were processed statistically as a stationary stochastic process. Based on the revised Pierson-Moskwitz spectra, the wave power spectra density function was formed. The spectral analysis method was used to calculate the power spectra of stress responses, and the probability characteristics were concluded. Based on an approximate calculation and approximate material fatigue parameters, the fatigue lives of critical joints of this steel structure were calculated. The checking calculation of fatigue strength of the critical joints was conducted. The research results show that the safety factor of fatigue strength of the critical joints can reach 3.

Load-Bearing Capacity of Reinforced Joint of Complicated Multi-dimensional Rectangular Hollow Section Truss

XU Hu, YU Zhixiang, ZHAO Shichun

2010, 23(5): 698-704. doi: 10. 3969/ j. issn. 0258-2724.

[Abstract](1103)

Abstract:
To compare the mechanical behaviors of multi-dimensional rectangular hollow section joints with different reinforced measures, the load-bearing capacity of a typical joint in the long-span steel structure roof of Hohhot eastern railway station was calculated and analyzed. Three kinds of joints, thickened cover plate joint, internal plate-stiffener joint and joint without reinforcement, were taken into account. Through numerical calculation, their static and hysteretic behaviors were obtained respectively by monotonic and reversed cyclic loadings, and their stiffnesses, load-bearing capacities and ductility variations were analyzed. In addition, low-speed dynamic damping factor was introduced into the Newton-Raphson equation to improve the convergence of high nonlinear problems such as local buckling. The research indicates that the deformation of the internal plate-stiffener joint is more uniform, however, compared with the internal plate-stiffener joint, the thickened cover plate joint is easy to operate and control the construction quality when they meet engineering requirements.

Experimental Research on Aseismic Behaviors of High-Strength Reinforced Concrete Frame Columns

FENG Hong, LI Liren, CHEN Yongqing

2010, 23(5): 705-712. doi: 10. 3969/ j. issn. 0258-2724.

[Abstract](1045)

Abstract:
In order to investigate the failure mode and seismic behaviors of high-strength reinforced concrete (HSRC) frame columns under the combined action of compression, bending and shear, quasi-static experiments on 19 such frame columns under low cyclic reversed loading were conducted. The influences of parameters such as steel content, axial compression ratios, stirrup ratio, shear-span ratio and concrete strength on the seismic behaviors of the HSRC frame columns were analyzed. The results show that the ultimate bearing capacity and ductility of HSRC columns improves considerably, compared with reinforced concrete (RC) columns; and hence the seismic performance of the HSRC columns is remarkably better. Under the combined action of compression, bending and shear, steel content, shear-span ratio and concrete strength play more dominant roles than other parameters in enhancing the seismic performance of HSRC columns. The rational parameters for HSRC columns whose 'is not less than 3 are 3. 5%-4. 5% steel content, 0. 45-0. 60 axial compression ratios, and 0. 8%-1. 0% transverse reinforcement ratio.

Limit Cycle Oscillation of Conical Shells with Standing Wave Flutter

FAN Chenguang, YANG Yiren, LU Li

2010, 23(5): 713-717. doi: 10. 3969/ j. issn. 0258-2724.

[Abstract](729)

Abstract:
To study the nonlinear fluttering response of a truncated conical shell under large-amplitude nonlinear vibrations, aeroelastic equations were derived using the aerodynamic force method of the piston theory. The discretization of the equations was realized with differential quadrature method. The effects of aerodynamic parameters on the amplitude of limit cycle oscillation were calculated under an assumption of standing-wave flutter mode. The degree of freedoms was reduced by taking the lower orders of natural modes to decrease the scale of nonlinear analysis. Reasonable accurate solutions were obtainable for the first 6 low orders of modes with reduced freedom of degrees. The shell motion turned into limit cycle oscillation via Hopf bifurcation as the aerodynamic pressure parameter increased to 7 312.

Void Identification of Concrete Pavement Slab Based on Transient Impulse Response

WANG Qi, 2, HAN Xi, YI Zhijian

2010, 23(5): 718-724. doi: 10. 3969/ j. issn. 0258-2724.

[Abstract](898)

Abstract:
In order to develop a special instrument for the detection of voids beneath a concrete pavement slab, cut down detection cost and simplify detection process, a transient impulse response method was proposed based on the analysis of the existing detection methods and the changes in the frequency and amplitude of plates with voids under a quantitative excitation. With this method, the bearing state of a concrete plate, with or without voids, can be verified preliminarily quantitatively from the number of resonance peaks and the value of the foundation frequency in the power spectrum density (PSD) curves (with a band extent of 0 to 1 000 Hz), and the boundary of a void can be detected based on the slope of the fitting curve of amplitude data. In order to expound the detection principle and process of the method, model plates with different cavity states were tested, and the bearing state of some real concrete pavement slabs were detected. The tested and detected results verify the validity and feasibility of the proposed method.

802. 11s Based Fast Transition Scheme for Wireless Mesh Network

FANG Xuming, SUN Shujie, HE Rong

2010, 23(5): 725-731. doi: 10. 3969/ j. issn. 0258-2724.

[Abstract](998)

Abstract:
In order to guarantee that a mobile station without mesh function can still keep a high transmission rate while it moves fast between wireless access points in the wireless mesh network (WMN), a layer two (L2) fast transition scheme based on 802. 11s WMN was proposed. This scheme employs the idea of cross-layer design, and the whole transition process is implemented at L2. It considers the information both from LLC (logic link control) sub-layer and from MAC (medium access control) sub-layer, combines and improves the related 802-11s schemes to greatly raise the efficiency of the transition. The simulation results show that compared with the transition scheme defined in the 802. 11s draft, the fast transition scheme can decrease the transition delay by 2 to 4 times and the number of packet drop by 2 to 8 times.

Blind Recognition of OFDM Signals Based on Multi-parameter Characteristics

GUO Lili, YU Zhiming

2010, 23(5): 732-738. doi: 10. 3969/ j. issn. 0258-2724.

[Abstract](1275)

Abstract:
A blind identification algorithm of multi-carrier modulation under the condition of Rayleigh fading channels was proposed to distinguish multi-carrier modulation OFDM (orthogonal frequency division multiplexing) signals and digital single-carrier signals (such as MASK (multiple amplitude shift keying), MFSK (multiple frequency shift keying), MPSK (multiple phase shift keying) and MQAM (multiple quadrature amplitude modulation) signals). This algorithm uses the characteristic parameters composed of high-order cumulants and trigonometric moments of signals for distinguishing single-carrier signals and multi-carrier OFDM signals to improve the traditional algorithm. It does not need to know the carrier frequency and the baud rate of the unknown signal in advance but deals with the intermediate frequency signal directly. The simulation results show that the proposed algorithm has the advantages of strong anti-multipath, high recognition rate, and it can gain a recognition rate of 100% when the SNR (signal noise radio) is greater than 0 dB.

Group Successive Interference Cancelator Based on Minimum Mean-Square Error Detection

ZHANG Donghong, 2, LIAO Guisheng

2010, 23(5): 739-744. doi: 10. 3969/ j. issn. 0258-2724.

[Abstract](916)

Abstract:
In order to reduce the demodulation delay of the conventional successive interference cancelator (SIC) and improve the BER (bit error rate) performance of each stage, an improved SIC was proposed based on the diagonal loading method and the interval grouping method. This improved SIC loads the correlation matrix of each stage diagonally. Through the selection of loading parameters, the output signal interference ratio of grouping users is maximized so that the minimum mean-square error (MMSE) detection can be realized and the update of the linear operator in each stage is only related to the diagonal loading parameters. Theoretic analysis and simulation results show that compared with the conventional SIC and the MMSE detector, the improved SIC reduces demodulation delays and achieves a better BER performance.

Key Recovery Attack on Stream Cipher Grain v1 and Its Improvement

YANG Wenfeng, HU Yupu, GAO Juntao

2010, 23(5): 745-750. doi: 10. 3969/ j. issn. 0258-2724.

[Abstract](730)

Abstract:
In order to probe into the security of the stream cipher Grain v1, three design weaknesses of the Grain v1 key-stream generator were pointed out by studying its structure. Based on the above work, a key recovery attack on the stream cipher Grain v1 with an intermediate state was proposed. Time complexity and memory complexity of the proposed attack are equal to the time complexity and memory complexity of the Grain v1 key-stream generator respectively. In order to resist the proposed attack, an improvement on the Grain v1 key-stream generator was made. The security analysis shows that the improved generator is secure against the proposed key recovery attack.

One-Way Hash Function Construction Based on Chaotic Message Expansion

GUO Wei, WANG Xiaomin, LIU Jing, HE Dake

2010, 23(5): 751-757. doi: 10. 3969/ j. issn. 0258-2724.

[Abstract](840)

Abstract:
In order to overcome the defects of the existing Hash algorithm, a novel Hash algorithm based on chaotic message expansion was proposed. This algorithm combines the advantages of a chaotic system and conventional one-way Hash function, follows the traditional Merkle-Damgard construction and compression function, and uses the chaotic map network to carry out the message expansion to further impact on the Hash process. Compared with the existing chaotic Hash functions, the proposed algorithm inherits the efficiency of the conventional Hash functions and improves the security. Theoretical and experimental results show that the proposed Hash algorithm possesses a good one-way property, a high avalanche effect and a strong collision resistance, as required by practical Hash functions, so it is easy to implement in parallel.

Comprehensive Evaluation of Risk Severity Level of Railway Signal System

ZHANG Yadong, GUO Jin, SHAN Na

2010, 23(5): 759-763. doi: 10. 3969/ j. issn. 0258-2724.

[Abstract](1746)

Abstract:
In order to assess the risk severity level of a railway signal system more scientifically, a comprehensive evaluation method of the risk severity level was proposed based on the expert evaluation method and the characteristic of the risk severity level of railway signal systems and by comprehensive application of the analytic hierarchy process, the weighted average integrated function and the maximum membership principle. By taking an automatic block system between railway stations as an example, the risk severity level of establishment of a block system with delay was analyzed and assessed using this comprehensive evaluation method. The proposed evaluation method can assess the risk severity level of a railway signal system more effectively and be used in the risk-based safety assessment of a railway signal system.

Integral Dropper Assembly fornOverhead Contact Line of High-Speed Railway

FANG Yan, GAO Shi-Bin

2010, 23(5): 763-767. doi: 10. 3969/ j. issn. 0258-2724.

[Abstract](1583)

Abstract:
In order to accurately calculate the dropper lengths，strictly control the contact wire height, improve the uniformity of elasticity and achieve good current collection quality, a new algorithm for integral dropper assembly based on form-finding for cable structure and finite element method was proposed. After analyzing the disadvantages of traditional method for dropper assembly, the new method and its application were illustrated. Through analysis of the catenary suspension of an overhead contact line between two anchoring points, a finite element model of the messenger wire was built with the contact wire height as the optimization objective. Meanwhile, the typical structure of overhead contact line systems and the real state of electric railway lines were considered to revise the model. The results of the application example shows that the resolution of the contact wire height after installation can be confined to ±7 mm, which meets the requirements of Construction Guide to Electric Traction Feeding Engineering of Passenger Dedicated Line.

Evaluation Model for Damage Extent of Roads in Wenchuan Earthquake-Stricken Areas Based on Remote Sensing Information

QIN Jun, CAO Yun-Gang, GENG Juan

2010, 23(5): 768-774. doi: 10. 3969/ j. issn. 0258-2724.

[Abstract](1235)

Abstract:
A low-altitude remote sensing data-based evaluation model for damage extent of roads was proposed for rapid assessment of transport facilities in Wenchuan earthquake-stricken areas. Spatial information about roads, bridges, tunnel portals and spatial distributional information about landslides, collapses and barrier lakes were extracted from large-scale true-color images of Wenchuan earthquake- stricken areas gained from low-altitude remote sensing platforms, and the corresponding thematic maps were drawn. Spatial coupling of a road and disaster bodies was taken as the criterion to judge whether this road is damaged. The road damage coefficient was get from the damage level of road structures due to individual disaster body, and the damage scale factor was obtained from the length of individual damaged road. Based on the above parameters, an evaluation model was established for the damage extent of roads in Wenchuan earthquake-stricken areas. The damage extent of Baisha-Xiajiaping section of Dujiangyan-Wenchuan highway was obtained using this evaluation model. The obtained result is consistent with the actual situation.

Planar Angle Measurement Based on Computer Vision

WANG De-Hui, YUAN Zhong-Fan, FAN Qiang-Wen

2010, 23(5): 775-780. doi: 10. 3969/ j. issn. 0258-2724.

[Abstract](822)

Abstract:
In order to solve the rapid angle measurement problem in the fields such as manufacturing, geology and control engineering, a non-contact angle measurement algorithm based on computer vision was proposed. In this algorithm, the camera's intrinsic parameters should be known before measurement and only one photograph of the target angle is required. And the photograph can be taken arbitrarily. When a set of parallel lines or an equational line segment is marked on each side of the angle, the equations of their images on the photograph can be acquired by using the line detection and the least square method. Then through calculating the intersection of the parallel lines'images or by using the harmonic cross-ratio, the coordinates of vanishing points on each side can be figured out. Finally, based on the imaging equation, the vanishing points'coordinates and the intrinsic parameters, the angle's value can be figured out. The experimental results show that even for a far distance measurement, the relative error of this algorithm can be controlled within 2%.

Additional Stresses in High-Strength Pile Composite Foundation under Embankment Load

LUO Qiang, ZHANG Minjing, ZHANG Liang, ZHANG Lixiang

2010, 23(5): 780-786. doi: 10. 3969/ j. issn. 0258-2724.

[Abstract](916)

Abstract:
In order to calculate additional stresses in high-strength pile composite foundation, the Mindlin and Boussinesq union method was used. This method calculates the additional stresses caused by pile load and inter-pile soil load separately. Based on test data from a soft foundation, the distribution regularity of the additional stresses around embankment center line in the foundation was emphatically discussed. The research result shows that the distribution of additional stresses along inter-pile soil axis has a wasp waist冶shape and is in good agreement with measured result. Additional stresses on piles are larger than those in inter-pile soil to indicate an evident load sharing effect in the reinforced area. In underlying strata, additional stresses calculated by the union method are nearly the same as those calculated by the Boussinesq method to indicate that additional stresses do not shift down evidently in a frictional pile composite foundation.

Cushion Effect Analysis of Pile-Net Composite Foundation Based on Field Tests

ZHANG Liang, LUO Qiang, LIU Xiaoxiao, ZHANG Lixiang, LIN Kun, ZHANG Shengli

2010, 23(5): 787-793. doi: 10. 3969/ j. issn. 0258-2724.

[Abstract](1019)

Abstract:
In order to provide a reference for the cushion design of pile-net composite foundation, four groups of field tests with different pile cap sizes were carried out, and data of foundation settlement, foundation pressure and cushion bar tension were obtained. The test result shows that pile cap can significantly decrease the pressure on pile top, the cushion bar tension and the settlement difference between piles and soil. The height of soil arches is related to the clear distance between piles and is about 0. 9 to 1. 3 times the clear distance between piles'axes. The pressure on pile top is uneven, and the pressure at the center of pile top is about 67% to 79% of the pressure at the edge. The maximum value of cushion bar tension is on pile top, and the cushion bar tension at the pile cap edge is bigger than that in the pile center.

Application of Point Safety Factor to Study on Spatial Sliding Mechanism of Landslide

YANG Tao, YOU Xiang, QIN Yongtao

2010, 23(5): 794-799. doi: 10. 3969/ j. issn. 0258-2724.

[Abstract](975)

Abstract:
In order to describe quantitatively the spatial sliding mechanism of landslides, a 3-D numerical model was set up, and spatial stress states and sliding directions of elements in slide zone were obtained. The ratio of shear strength to shear stress paralleling to sliding direction was defined as point safety factor of element. Therefore, the spatial sliding mechanism of a landslide can be evaluated through analyzing the spatial distribution characteristic of point safety factor in a slide zone. The research indicates that the distribution of point safety factor in a slide zone is continuous and shows the same regularity as sliding mechanism given by macrogeologic analyses. As a result, point safety factor can be taken as a quantitative assessment index of spatial sliding mechanism of landslides.

Syntheses and Structure of Drug-Loaded Multilayer Composite

ZHANG Zhibin, 2, WU Jing, SHUAI Yunfeng, YAN Xiaoli, WAN Changxiu

2010, 23(5): 800-804. doi: 10. 3969/ j. issn. 0258-2724.

[Abstract](1187)

Abstract:
Drug-loaded CS ( chitosan), TCS ( tetracycline hydrochloride/ chitosan/ sodium alginate) composite, and multilayer composite microspheres for bone repair were synthesized respectively by the emulsion-crosslinking method, coacervation phase separation method, and a heated suspension composition process. The structures of the synthesized samples were analyzed by scanning electronic microscope. The results showed that the drug-loaded CS microspheres with CS of relative molecular mass of 420*103 were round, easy to disperse, and well-wrapped by sodium alginate, and that the sieve aperture sizes in the drug-loaded multilayer composite microspheres were about 100 200 um, suitable for bone cell to grow in as a tissue engineering scaffold material.

Effect of Aramid Fibre and Pulp Morphologies on Properties of Sheet

ZHANG Sufeng, 2, LIU Wen, ZHANG Meiyun

2010, 23(5): 805-810. doi: 10. 3969/ j. issn. 0258-2724.

[Abstract](930)

Abstract:
In order to reveal the relationship between the morphology of aramid fibre and pulp and the sheet structures and properties, the morphologies of aramid fibre and fibrids (pulp) were characterized using light microscopy (LM), scanning electrical microscopy (SEM), and atomic force microscopy (AFM); the fibre distribution was analyzed by fibre screening technique; and the fibre length, curl and kink index were analyzed by fibre quality analyzer (FQA). The properties of aramid fibre and pulp for sheet making and the effect of pulp weight proportions in sheet composition were investigated. The results showed that the aramid fibre presented in a solid, nearly cylinder shape, and the fibrills spread regularly on the fibre surface, parallel with the fibre axis. The aramid pulp was in a small, ribbon-like shape, and evenly dispersed in water. The fibril content in the pulps was 28. 59%. The optimal furnish ratio of pulp to fibre was 1. 5 :1, and a laminating sheet making procedure with various furnish ratios of pulp to fibre at 1. 5 :1(1/3) for the top and bottom layers and at 1 颐1(2/3) for the medium layer was suggested to be more beneficial to the sheet structure and properties.

Determination Method of the Optimal Revenue-Sharing Coefficient in Three-Echelon Logistics Service Supply Chain

LIU Wei-Hua

2010, 23(5): 811-816. doi: 10. 3969/ j. issn. 0258-2724.

[Abstract](1195)

Abstract:
In order to determine the revenue-sharing coefficient of supply chain with a revenue-sharing contract, a Stackelberg game model with the logistics service integrator as a leader was built by taking the non-storage property of logistics service supply chain into consideration. On the basis of the revenue-sharing contract, the value range of the revenue-sharing coefficient was obtained. Then, a solution model for the optimal revenue-sharing coefficient in three-echelon logistics service supply chain was built in a stochastic demand environment, by introducing an equity entropy function to describe the equity principle of profit assignment. With this model, the optimal revenue-sharing coefficient can be found accurately. An example shows that when the revenue-sharing coefficient is 0. 840 for the logistics service integrator and 0. 848 for the logistics service provider the maximal equity entropy is 0. 999.

Trajectory Planning Model of 2-Directional Air Traffic Flows Based on Improved Clearance Strategy

ZHANG Chen, HU Ming-Hua, ZHANG Jin

2010, 23(5): 817-823. doi: 10. 3969/ j. issn. 0258-2724.

[Abstract](1548)

Abstract:
To study the traffic patterns of the 2-directional high-density air traffic flows, aircraft trajectory planning methods were discussed. Based on the model of the offset maneuver strategy, an improved strategy was proposed through a geometric analysis of the trajectories generated in a distributed decision-making environment of the self-separation operational concept, and a trajectory planning model with the improved strategy was built. The relationship among the maneuver buffer area length, width, and revised clearance position was deduced. The simulation results show that when the route crossing angles are 90'and 45', the shortest maneuver buffer area lengths under the improved strategy are 35. 9 and 48. 4 km, respectively. Moreover, under the improved offset strategy, the widths of the airspace protection area for the same route crossing angle settings are shortened by at most 21. 1% and 39. 3%, compared with those under the original offset strategy. Therefore, the width of the protection area of the new strategy is more close to the current real route width, which indicates that the new strategy is easier to accomplish and adjust in practical applications.

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2010 Vol. 23, No. 5