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• 2017 Volume 38 Issue 6
  Published: 10 November 2017

    

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  Lane detection method based on clustering algorithm

  CAI Ying-Feng, GAO Li, CHEN Long, YUAN Jiang, CHEN Jun

  2017, 38(6): 621-625. https://doi.org/10.3969/j.issn.1671-7775.2017.06.001

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  To solve the problem that the uncertain external environment was easy to interfere the existing lane detection algorithms and lead to false detection, a new lane detection method was proposed based on improved Hough transform. The image was filtered, and the edge was recognized to perform the two valued preprocessing. After preprocessing, the feature points containing lane edges were extracted by behavior units. The feature points were constructed according to Euclidean distance, and the relationship was established at longitudinal direction. The clustering algorithm was used to combinate the feature points and isolate the feature points with clear targets, and the calculation error of feature point interference and Hough transform was reduced to improve realtime performance and calculation accuracy. The algorithm was checked by lane images with about 4 000 frames of different time periods and external environment. The experimental results show that the proposed method can well realize lane detection under various environment, and the correct rate is 99.18% in fine weather with that of 97.45% in adverse weather.
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  Dynamic meshing characteristics analysis of differential gears based on finite element

  LI Hai-Peng, WANG Liang-Mo, CHEN Gang, XIA Han-Guan, DONG Yi

  2017, 38(6): 626-631. https://doi.org/10.3969/j.issn.1671-7775.2017.06.002

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   Under two typical conditions during car driving, the rotational speed and the torque distribution of car differential pinion gear and side gear were calculated. Based on the finite element dynamic simulation method, the finite element model was established to simulate the dynamic meshing of differential gears, and the stress distribution of gears was investigated. The influence of friction coefficient between contact surfaces on the stress distribution was analyzed to show that the contact stress was increased with the increasing of friction coefficient. Taking the maximum contact stress of dynamic meshing as static load input, the fatigue life of gears was calculated based on the nominal stress method. The results show that the dangerous position occurs in the gear tooth contact area and the gear tooth root, and the bending fatigue life can meet the design requirements. The fatigue life of differential gears can be effectively predicted by dynamic simulation of gears and fatigue life analysis method.
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  Analysis on adaptability of automobile lift loaded braking test

  HUANG Wan-You, YU Ming-Jin, FAN Yan-Yan, TANG Xiang-Chen, TIAN Xue-Song

  2017, 38(6): 632-637. https://doi.org/10.3969/j.issn.1671-7775.2017.06.003

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  According to GB 21861—2014, the loaded braking performance test should be added into vehicle test programs from the 1st March of 2017, and the loading method should apply lift loading on brake test platform. Using the platform with adjustable lifting height, the adaptability of the test method of lift loading for vehicles was investigated, and the test principles and the detail method of lift loaded braking test were analyzed. The lift loaded braking tests were performed for twoaxle automobile, dualaxis automobile, threeaxle automobile and threeaxis trailer. The test results show that it is not suitable for twoaxle and dualaxis automobiles to adopt lift loaded braking test because the test results are not obvious. For threeaxle automobile, the lifted axle load is increased by 79.2% after lift loading, and the braking force is increased by 46.4%. The increasing range of axle load after lift loading is great, which indicates that it is suitable to utilize platform lift loading method on intermediate axle of threeaxle automobiles. For threeaxis trailer, the lifted axle load has significant change after lift loading, which shows that it is suitable to adopt platform lift loading method to conduct loaded braking tests.
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  Evolution of gas solid pollutants in photochemical reaction of automobile exhaust and atmosphere

  DAI Bing, SHI Xin, YUAN Yin-Nan, QIAN Peng, YANG Zong-Ling

  2017, 38(6): 638-644. https://doi.org/10.3969/j.issn.1671-7775.2017.06.004

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  Under the different temperature and humidity conditions, the photochemical reaction experiments of automobile exhaust and atmosphere were carried out with the smog chamber system. By measuring the substance concentration at different time, the generation and evolution laws of different gases and solids in the photochemical reaction of automobile exhaust and atmosphere were revealed. The experimental results show that in the photochemical reaction of automobile exhaust and atmosphere, NO and HC mainly come from exhaust gas, while NO2 and O3 are mainly new products with mainly secondary particles of PM2.5. With the increasing of reaction time, the volume fractions of NO and HC are declined, and the declining rate of NO volume fraction is negatively related to temperature and humidity. The declining rate of HC volume fraction is positively related to temperature and humidity. The volume fractions of NO2 and O3 and the mass concentration of PM2.5 are rised rapidly in the beginning with latter gradual change, and the formation rates of NO2, O3 and PM2.5 are positively related to the humidity. Compared with temperature, the relative humidity has greater effect on the rate of pollutant change. The main period of generating secondary particles in the photochemical reaction of automobile exhaust and atmosphere is initial 1.5 h. The high exhaust gas content is beneficial to generating secondary particles. The generated secondary particulates for diesel vehicle in the atmosphere are more than those for gasoline vehicle.
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  Influence of damper indicator diagram area on vehicle ride comfort

  YIN Chun-Fang, ZHANG Jin-Chao, WANG Shao-Hua, SUN Xiao-Qiang, XU Xing

  2017, 38(6): 645-651. https://doi.org/10.3969/j.issn.1671-7775.2017.06.005

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  To investigate the effects of damper indicator characteristics on vehicle ride comfort, the mathematical model of hydraulic doubletube damper was established based on the fluid mechanics theory, and the accuracy was verified by bench tests. According to the damper external characteristics simulation curve, a quantitative indicator of damper indicator diagram total area was proposed. Combining the vibration principles of vehicle system, the mathematical relationships among indicator diagram total area and suspension performance indices of sprung mass vertical vibration acceleration, suspension dynamic travel and tire dynamic load were established, and the effect law was analyzed quantitatively based on the fullcar vibration model. The results show that there is apparent deterioration phenomenon of vehicle ride comfort and safety when the indicator diagram total area is small. When the total area is too large, the sprung mass vibration acceleration and the tire dynamic load are increased, and the vibration energy distribution in frequency domain is influenced at the same time.
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  Torque distribution strategy of PHEV based on FCMAC neural network

  ZHANG Niao-Na, ZHOU Chang-Zhe, GAO Ze-Lin, LI Yan-Yang

  2017, 38(6): 652-657. https://doi.org/10.3969/j.issn.1671-7775.2017.06.006

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  Due to the important impact of hybrid electric vehicle (HEV) distribution strategy on vehicle fuel economy and emissions, a vehicle torque distribution method was propared based on fuzzy cerebellar model articulation controller (FCMAC) neural network control. Based on the pregearbox twinaxle torque coupled PHEV, the FCMAC neural network control strategy was established with engine output torque as target. After discretization, the rule multiplied Gaussian fuzzy membership degree was inputted into FCMAC, and the engine torque was outputted through hash mapping and weight adjustment to realize the torque distribution of HEV. The simulation model was established on AVLCruise and Matlab/Simulink platform, and the simulation results were compared with those based on logic threshold control strategy. The results show that the FCMAC control strategy is better than the logic threshold control strategy under NEDC condition, and the fuel economy and the emissions of vehicle are improved.
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  Electrospraying modes from capillary and mechanical analysis

  XIA Lei, WANG Zhen-Tao, WANG Xiao-Ying, ZHAN Shui-Qing, DONG Qing-Ming

  2017, 38(6): 658-664. https://doi.org/10.3969/j.issn.1671-7775.2017.06.007

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  Based on microscopic highspeed camera technology, the electrospraying visualization of anhydrous ethanol was investigated in stainless steel singlecapillary. Based on the outlet of capillary meniscus and the formation of microjet or droplet morphology, the electrospraying modes of anhydrous alcohol and the transformation process were analyzed. The typical sprayingmodes include dripping, microdripping, spindle, multispindle, oscillatingjet, precessionjet, conejet and multijet modes. The forces acting on microjet and droplets under different sprayingmodes were analyzed, and the relationship between force and motion pattern of microjet, droplet and sprayingmodes was discussed. The results indicate that the capillary electrospraying modes are closely associated with applied voltage. With the increasing of voltage, the electrospraying modes gradually transform from dripping, spindle modes to conejet and multijet modes with orderly transition. For different electrospraying modes, gravity, electric field force, resistance, surface tension, dielectric electrophoretic force and deformation force play different roles on motion pattern and trajectory of microjet or droplet. For low electric field strength, the gravity dominates the droplet motion, and the droplet becomes spherical under the surface tension. For high electric field strength, the electric field force dominates the motion of microjet or droplets, and it shows various electrospraying modes under different electric forces.
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  Numerical simulation for downwash flow field of large-size plant protection unmanned helicopter hedgehopping

  XU Wen-Bin, WANG Jun-Feng, WEN Jian-Long, WANG Xiao-Ying

  2017, 38(6): 665-671. https://doi.org/10.3969/j.issn.1671-7775.2017.06.008

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  To investigate the flow field characteristics of largesize plant protection unmanned helicopter hedgehopping，the numerical simulations were conducted,and the fullsize physical model of the largesize helicopter was established. The threedimensional    flow field of largesize unmanned helicopter hedgehopping was simulated by SST kω turbulent flow model. The results show that the downwash flow field  is relatively disorder under the fuselage because  of the obstruction of fuselage.The distribution characteristics of downwash are generally consistent at the same nozzle location of different height，however   the distribution characteristics of downwash are quite different for the same flight altitude at different nozzle location. The vertical velocity is increased with latter decreasing along the direction of rotor at the spray boom location，and the maximum velocity is obtained near the x/R value of 0.8. The width of plant canopy velocity  is increased with the decreasing of flying height，and the better fly height of H is 4 m. The boom of UAV should be installed in the area with z from -1.50 to -2.00 m and x from -0.50 to 0.50 m.
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  Design of postharvest infield grading system for navel orange based on machine vision

  WANG Gan, SUN Li, LI Xue-Mei, ZHANG Ming, 吕Qiang , CAI Jian-Rong

  2017, 38(6): 672-676. https://doi.org/10.3969/j.issn.1671-7775.2017.06.009

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  To meet the demand of fruit farmers′ timely grading of navel oranges, a set of navel orange postharvest field grading system was designed based on machine vision, which was composed of conveying system, visual system and sorting system. The size of navel orange, the number of surface defects and the defect area were detected by the proposed system. The fruit was automatically graded according to the predetermined comprehensive assessment standard. The experimental results show that the average detection time of single picture is less than 30 ms, and the detection error of size is less than 3% with defect detection rate of 99% and defect area detection error less than 7%. Compared with the traditional detection system, the proposed system has the advantages of high detection speed and compact design, which is suitable for infiled grading of navel orange.
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  Moving object detection method based on complex fuzzy logic system

  LI Zi-Long, BAO Rong, LIU Wei-Ming

  2017, 38(6): 677-681. https://doi.org/10.3969/j.issn.1671-7775.2017.06.010

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  To improve the accuracy, antijamming capability and  efficiency of background modeling in complex  scenes, the moving object detection method was proposed based on complex fuzzy logic system. The complex TakagiSugenoKang (TSK) fuzzy logic system was used as the estimation of background model, and a hybrid learning method combining particle swarm optimization (PSO) and kernel least mean square (KLMS) was used to learn the complex fuzzy logic system. The foreground pixels were regarded as outliers relative to the background ones, and an outlier separator method was proposed to train the complex fuzzy logic system. The foreground pixels were distinguished according to the comparison between estimated background model and foreground image. To verify the proposed method, the video sequences under three scenes of campus, highway and water surface were determined, and the detection performance was compared with those of other three classical methods. The results show that by the proposed method, high accuracy can be obtained under the conditions of dynamic background，illumination changes and camera vibration. The similarity measure value is 0.1 higher than those of other three methods with detection speed of 22 f·s-1, which can meet real time requirements.
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  Design of wideband Doherty power amplifier based on two impedance matching network

  KONG Wa, XIA Jing

  2017, 38(6): 682-686. https://doi.org/10.3969/j.issn.1671-7775.2017.06.011

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  To meet the design requirements of highefficiency and broadband of power amplifiers in wireless communication systems employing modulation signals with high peak to average power ratio (PAPR), an improved Doherty power amplifier (DPA) was investigated. To achieve the impedance transformations both in low power region and at saturation, a two impedance matching network design was proposed to simulate and design the main and auxiliary output matching networks, which could simplify the load modulation network of DPA and extend the bandwidth. The wideband DPA with 2.30～2.80 GHz was designed and measured, and the proposed method availability was verified. The results show that the designed DPA has the gain fluctuation less than 2 dB and the saturated output power more than 43.5 dBm over the frequency band of 2.30～2.80 GHz, while the saturated efficiency is from 66% to 71% with 6 dB backoff efficiency from 48% to 59%. The designed wideband DPA can satisfy the efficiency requirement of future wireless communication systems employing modulation signals with high PAPR.
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  Survey of decoupling control strategies for bearingless synchronous reluctance motor

  DIAO Xiao-Yan, ZHU Huang-Qiu

  2017, 38(6): 687-695. https://doi.org/10.3969/j.issn.1671-7775.2017.06.012

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  Aiming at the strong coupling problem between electromagnetic torque and radial suspension force in bearingless synchronous reluctance motors (BSRMs), various decoupling control methods were investigated and analyzed. The rotor suspension principle and the mathematical model of BSRMs were introduced, and the reported decoupling control strategies of BSRMs were summarized. The principle, performance, limitation and development of some reported control strategies for BSRMs including feedforward and feedback compensation control, inverse system control, neural network inverse control, support vector machine inverse control, differential geometry based exact linearization control and direct torque and suspension force control strategy were analyzed respectively. According to the characteristics of BSRMs, the future research directions were pointed out. Some suggestions for BSRMs of precise mathematical model construction with magnetic saturation, motor parameters online identification, application of intelligent control to increase disturbance attenuation capacity, parameter optimal design of decoupling controller and nonlinear controller design based on nonlinear control theory are proposed.
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  Zero-shot learning based on spatial pyramid matching using sparse coding

  DONG Su-Hui, XU Yong-Gang, CHEN Chen

  2017, 38(6): 696-702. https://doi.org/10.3969/j.issn.1671-7775.2017.06.013

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  The lowlevel visual features of images to train attribute classifiers are used in the attributebased zeroshot learning methods generally, and the corresponding classification accuracy heavily depends on specific lowlevel features. A zeroshot learning method was proposed based on spatial pyramid matching using sparse coding (SSPM_IAP). The structure flow chart of system was given, and the SIFT features were extracted from original images. The features were extracted and reduced by spatial pyramid matching using sparse coding and max pooling. The exacted image features were used to train the attribute prediction model. The SSPM_IAP algorithm was proposed to predict image attributes and classify images under the zeroshot setting. The comparison experiments were completed on Shoes and OSR datasets. The results show that compared with several popular zeroshot learning methods, the experimental time consumption is reduced, and the proposed method can achieve more accurate attribute prediction and better zeroshot image classification.
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  Experiment of nonuniform excitation for bridge based on single shaking table

  WU Duo, LIU Lai-Jun, LI Qing-Ning, ZHANG Xia, XUE Cheng-Feng

  2017, 38(6): 703-707. https://doi.org/10.3969/j.issn.1671-7775.2017.06.014

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  To investigate the dynamic response of bridges under nonuniform excitation, a 1/20 reducedscale continuous beam bridge was designed and fabricated. The seismic simulation shaking table test with nonuniform excitation input was carried out. The extension table was set for the single small vibration table, and the table input excitation was changed to improve the shaking table equipment. The ElCentro and Taft waves suitable for the class Ⅱ field were selected, and the macroscopic failure modes and the time history displacement curve of main parts were analyzed under different seismic intensities. The experimental results show that the bridge damage is increased with the increasing of seismic intensity, and the difference of seismic excitation input between original table and extended table becomes obvious after improving the shaking table equipment. The improved equipment can be used for nonuniform seismic excitation shaking table test of large span bridge structure, and the dynamic response of bridges under seismic effect can also be obtained.
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  Acceleration response spectrum analysis of large span floor under pedestrian load

  GAO Feng, CAO Li-Lin, ZHUANG Qing-Wen

  2017, 38(6): 708-712. https://doi.org/10.3969/j.issn.1671-7775.2017.06.015

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  Acceleration response spectrum research in numerical analysis method was introduced, and the defect was pointed out. By APDL, the longspan floor finite element calculation model was established based on standard pedestrian excitation load mode, and the maximum acceleration response spectrum curve was obtained by a large number of time history analysis calculation. The effects of detecting position, damping, span and pedestrians on the acceleration of floor were analyzed and compared with recommending results of some scholars. The results show that the finite element analysis can eliminate the error due to the flexural function instead of horizontal displacement response during numerical analysis. The problem of small structure vibration response by using the first type vibration acceleration response instead of the acceleration response of the structure is solved by the proposed method.
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  Effect and mechanism of coupling with frost and salt on concrete performance with CWCPM

  XUE Cui-Zhen, SHEN Ai-Qin, GUO Yin-Chuan, LI Hui

  2017, 38(6): 713-718. https://doi.org/10.3969/j.issn.1671-7775.2017.06.016

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  To investigate the frost resistance performance of smallscale concrete under different CWCPM contents and watercement ratios and to investigate the freezethaw damage to the smallscale concrete under different salt solution concentrations, XRD and mercury intrusion porosimetry tests were carried out, and the improving mechanism of CWCPM to the frost resistance performance of smallscale concrete was analyzed. The results show that the concrete has the best frost resistance performance when the CWCPM dosage is 30%. The worst performance is obtained when the concentration of salt solution is 3.5%. The addition of CWCPM can reduce Ca(OH)2 content and improve the composition of concrete hydration products to refine the internal pore structure of concrete. The water permeability, the freezing rate, the internal hydrostatic pressure and the osmotic pressure are reduced to improve the antifreezing performance.
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  Experiment on tensioncompression ratio of steel fiber reinforced concrete

  ZHANG Yan-Nian, LI Zhen-Hui, LIU Xiao-Yang, ZHENG Yi, HAN Dong

  2017, 38(6): 719-723. https://doi.org/10.3969/j.issn.1671-7775.2017.06.017

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  With the considerations of fiber volume fraction, matrix strength concrete and steel fiber type, the standard sample of 150 mm×150 mm×150 mm cube was used to conduct compressive and splitting tensile tests and the effects of parameters on tensioncompression ratio of concrete were analyzed. The results show that steel fiber can increase the compressive and splitting tensile strengths of concrete ,and the concrete compression and tensile failure modes are significantly improved with good integrity. Steel fiber can enhance the tensioncompression ratio of concrete, and the ratio is increased with the increasing of steel fiber volume fraction with the largest increasing amplitude of 27.4%. The ratio of tensioncompression is decreased with the increasing of matrix strength, and the decreasing amplitude is obviously reduced than ordinary concrete. Corrugated steel fiber and end hook type steel fiber can both improve the tensioncompression ratio of concrete,and corrugated steel fiber is superior to end hook.The improving effect of screw type steel fiber is the worst with reduced concrete tensioncompression ratio.
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  Experiment of behavior of Hsteel columns strengthened with partially encased concrete

  YIN Zhan-Zhong, SUN Yuan, XU Ji-Xiang, LI Jin-Ming

  2017, 38(6): 724-730. https://doi.org/10.3969/j.issn.1671-7775.2017.06.018

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  The ordinary Hsteel frame columns were partially encased with concrete for strengthening to prepare Partially Encased Composite Columns (PEC Column). The uniaxial compression tests of six specimens of PEC Column with two difference cross sections were conducted, the text analysis and summarize the mechanical characteristics of loaddisplacement curve, bearing capacity, stiffness, ductility and damage mode were analyzed for PEC Column with three different kinds of structures. The results show that the PEC column has high load bearing capacity and stiffness. According to the test results of three different structure forms of frame column, the specimens with tension bar have higher bearing capacity and larger stiffness. The tension bar can wall limit the relative drift between concrete and steel, which improves the bearing capacity of concrete. Setting tension bar in frame columns, the concrete is subjected to larger limitation to obtain better binding power between concrete and steel plate. The yield displacement is increased, and the ultimate displacement of frame column is decreased with reduced ductility.
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  Cracking mechanism of TopDown cracking in asphalt pavements based on fracture mechanics

  CHEN Zheng-Wei, ZHANG Hong-Liang, ZHANG Shan-Shan

  2017, 38(6): 731-736. https://doi.org/10.3969/j.issn.1671-7775.2017.06.019

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  Based on the threedimensional finite element analysis in ABAQUS software, with considerations of the modulus gradient of asphalt pavement by aging and temperature gradient, the suddenly cooled down temperature and the concentration of tire edge stress, three seasons of spring, summer and winter and three conditions of slowing cool down before aging, slowing cool down after aging and sudden cooling down after aging were selected to establish nine finite element asphalt pavement models with cracks. The stress intensity factors of TopDown cracking(TDC) under different working conditions were analyzed. Combining the theory of the maximum circumferential tensile stress, the cracking mechanism and the prediction method of TDC were given. The results show that the stress intensity factors of shear mode are the main cause for the propagation of cracks under the conditions of slowing cool down before aging and slowing cool down after aging. The stress intensity factors of opening mode are the main cause for the propagation of cracks under the condition of sudden cooling down after aging.
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  Stability criterion for riverbed based on minimum rate of energy dissipation

  GAO Shi-Zhao, ZHAO Li-Na, YOU Zai-Jin, ZHENG Chun-Mei

  2017, 38(6): 737-744. https://doi.org/10.3969/j.issn.1671-7775.2017.06.020

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  To solve the problem of riverbed stability trend,the riverbed stability criterion was proposed based on the minimum rate of energy dissipation, Reynolds averaging method and variational principle. The riverbed stability criterion was verified by comparing literature data and longitudinal section stability coefficient. The 21years′ hydrological data of 1972, 1973, 1975—1980, 1982, 1985, 1987, 1988, 1991—2000 for six reaches of the Yellow River downstream formed by seven hydrometric stations from Huayuankou to Lijin were used to analysis the riverbed stability of the Yellow River downstream. The results show that the stability of the Yellow River downstream riverbed is gradually reduced, and the most unstable sections are in Sunkou and Aikou with riverbank needing to be reinforced. The reduced stability is due to that the Yellow River is aboveground river formed by the gradual silting of hyperconcentrated flow sediment at midstream and downstream with raised riverbed.