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Numerical simulation of incipient particle motion 预览
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作者 Ali Nasrollahi Ali Akbar Salehi Neyshabouri +1 位作者 Goodarz Ahmadi Masoud Montazeri Namin 《国际泥沙研究:英文版》 SCIE 2020年第1期1-14,共14页
A two-dimensional(2D)computational model for simulation of incipient sediment motion for noncohesive uniform and non-uniform particles on a horizontal bed was developed using the Discrete Element Method(DEM).The model... A two-dimensional(2D)computational model for simulation of incipient sediment motion for noncohesive uniform and non-uniform particles on a horizontal bed was developed using the Discrete Element Method(DEM).The model was calibrated and verified using various experimental data reported in the literature and compared with different theories of incipient particle motion.Sensitivity analysis was done and the effects of relevant parameters were determined.In addition to hydrodynamic forces such as drag,shear lift and Magnus force,the particle-particle interaction effects were included in the model.The asymptotic critical mobility number was evaluated for various critical particle Reynolds numbers(R*)in the range of very small and very large R*.The obtained curve is classified into four regions.It was found that in the linear region,the drag force has the principal role on the initiation of motion.Moreover,the critical mobility number is independent of particle diameter.A procedure for estimating the critical shear velocity directly from the information on particle diameter and roughness height was developed.Finally,the mechanism of incipient motion for the different regions was studied and the effect of different forces on the incipient particle motion was obtained.It was found that the maximum effects of lift and Magnus forces were,respectively,less than ten and twenty percent of the total force.The drag force,however,was typically the dominant force accounting for majority of the net hydrodynamic force acting on sediment particles at the onset of incipient motion. 展开更多
关键词 Incipient motion Shields curve Numerical simulation Drag force Lift force
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Two-dimensional numerical simulation of sediment transport usingimproved critical shear stress methods 预览
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作者 Zhiyong Feng Guangming Tan +3 位作者 Junqiang Xia Caiwen Shu Peng Chen Ran Yi 《国际泥沙研究:英文版》 SCIE 2020年第1期15-26,共12页
Research on the critical shear stresses for erosion and deposition for cohesive sediment has attracted substantial attention from both engineering and theoretical viewpoints due to their importance in sediment transpo... Research on the critical shear stresses for erosion and deposition for cohesive sediment has attracted substantial attention from both engineering and theoretical viewpoints due to their importance in sediment transport theory.Previous studies have proposed a large number of empirical and semiempirical methods to estimate the critical erosion and deposition shear stress,but comparative analyses and validation of the existing methods are still lacking,leaving questions regarding the applicability ranges of the methods.The current paper evaluates the performance and applicability range of five critical erosion shear stress methods derived from different hypotheses on sediment transport for flume experiments and natural tidal rivers using a process-based model.In addition,the effect of the critical deposition shear stress on sediment transport is investigated.The results show that the different critical erosion shear stress methods yield distinctly different prediction results,and their performance and applicability ranges are discussed by comparing their predictions with measured sediment concentrations from the Shenzhen River and measured geometric changes from the Partheniades'flume experiment.The hiding and exposure effect has been recognized as a crucial factor in the incipient motion of sediment on nonuniform beds.A sensitivity analysis of selective deposition and continuous deposition justifies the existence of the critical deposition shear stress.The current study highlights the performance and applicability ranges of the existing critical shear stress methods in sediment transport modeling for uniform and nonuniform beds,which will enrich understanding of the underlying mechanisms of erosion and deposition of cohesive sediment. 展开更多
关键词 Cohesive sediment Critical shear stress Hiding and exposure effect Numerical modeling Shenzhen river
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An overview of particle-based numerical manifold method and its application to dynamic rock fracturing 预览
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作者 Xing Li Jian Zhao 《岩石力学与岩土工程学报:英文版》 CSCD 2019年第3期684-700,共17页
This review summarizes the development of particle-based numerical manifold method(PNMM)and its applications to rock dynamics.The fundamental principle of numerical manifold method(NMM)is first briefly introduced.Then... This review summarizes the development of particle-based numerical manifold method(PNMM)and its applications to rock dynamics.The fundamental principle of numerical manifold method(NMM)is first briefly introduced.Then,the history of the newly developed PNMM is given.Basic idea of PNMM and its simulation procedure are presented.Considering that PNMM could be regarded as an NMM-based model,a comparison of PNMM and NMM is discussed from several points of view in this paper.Besides,accomplished applications of PNMM to the dynamic rock fracturing are also reviewed.Finally,some recommendations are provided for the future work of PNMM. 展开更多
关键词 Dynamic rock fracturing NUMERICAL modeling NUMERICAL MANIFOLD method(NMM) Particle-based NUMERICAL MANIFOLD method(PNMM)
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Numerical Taxonomy and Bayes Discriminant Analysis on 42 Fossil Species in Dicksoniaceae from China 预览
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作者 XIN Cunlin WANG Jingjing WANG Luhan and ZHANG Yamei 《地质学报:英文版》 SCIE CAS CSCD 2019年第1期183-198,共16页
As the basal group of Polypodiales, the specific taxonomy of Dicksoniaceae is still being debated. As a quantitative analysis method, numerical taxonomy has been applied to the taxonomic study of many plant families a... As the basal group of Polypodiales, the specific taxonomy of Dicksoniaceae is still being debated. As a quantitative analysis method, numerical taxonomy has been applied to the taxonomic study of many plant families and genera in recent years due to its simplicity and high accuracy. However, the numerical analysis of the Dicksoniaceae fossils has not been reported at present. In the present study, the pinnule morphological data of 42 Mesozoic fossil species of the Dicksoniaceae were analyzed using cluster analysis, principal component analysis and correlation analysis. The results revealed that 42 taxonomic units could be divided into six representative groups, which are consistent with the traditional taxonomy. After screening, an identification key on 28 fossil species of four genera with a definite taxonomic position was established. According to the quantitative analysis, a Bayes discriminant model was established for the selected species. Lastly, the model was tested using the morphological data of the fossil pinnules in Dicksoniaceae from the Yaojie Formation, suggesting that the discriminant model is accurate to a certain extent. As a result, the numerical taxonomy can be applied to the classification of the Dicksoniaceae fossils. 展开更多
关键词 Dicksoniaceae FOSSIL PLANTS NUMERICAL TAXONOMY BAYES DISCRIMINANT analysis China
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A CFD simulation of wave loads on a pile-type oscillating-water-column device 预览
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作者 Zhenhua Huang Conghao Xu Shijie Huang 《水动力学研究与进展:英文版》 SCIE EI CSCD 2019年第1期41-49,共9页
Oscillating-water-column (OWC) devices provide a practical and convenient way to convert wave energy to electricity.Wave loads on bottom-sitting WECs are important design parameters for their foundation safety.This st... Oscillating-water-column (OWC) devices provide a practical and convenient way to convert wave energy to electricity.Wave loads on bottom-sitting WECs are important design parameters for their foundation safety.This study considers an OWC integrated into a bottom-sitting pile structure (an OWC pile).Results from three-dimensional numerical simulations are used to examine the wave loads on an OWC pile.It appears that viscous loads and lateral loads are relatively small.Both the inline and vertical wave forces and the resulting overturning moment are not sensitive to the variability in wave period,but increase with wave height.Scales suitable for the wave forces and overturning moment are proposed for estimating wave loads on the OWC pile. 展开更多
关键词 Numerical simulation wave energy CONVERSION OPENFOAM FOUNDATION safety
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Effect of self-weight consolidation on a hydro-sedimentological modelfor the Río de la Plata estuary 预览
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作者 Pablo Santoro Mónica Fossati +3 位作者 Pablo Tassi Nicolas Huybrechts Damien Pham Van Bang Ismael Piedra-Cueva 《国际泥沙研究:英文版》 SCIE 2019年第5期444-454,共11页
The effect of the consolidation process on the morphodynamics and fine sediment dynamics of the Río de la Plata estuary is explored through a circulation-wave-sediment transport model. The consolidation model is ... The effect of the consolidation process on the morphodynamics and fine sediment dynamics of the Río de la Plata estuary is explored through a circulation-wave-sediment transport model. The consolidation model is calibrated based on settling column experimental data. Different simulations are done in order to initialize the mud layer distribution and to investigate the impact of different erosion parameter assumptions on the modeled sediment dynamics. Finally a two-year simulation is done with and without the consolidation process and realistic hydrodynamic forcings. Considering the consolidation process, the model correctly reproduces measured vertical density profiles in the Montevideo Bay access channel. The simulated suspended sediment dynamics behavior in Montevideo Bay with the consolidation process provides a more realistic deposition pattern in regard to the dredging activities. 展开更多
关键词 COHESIVE SEDIMENT Self-weight CONSOLIDATION MORPHODYNAMICS Numerical modeling
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A 3D Finite Radon Transform 预览
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作者 Mustapha Boukour Abderrahim El Omri 《数学和系统科学:英文版》 2019年第2期64-69,共6页
The present work is devoted to the development of the extension of FRT (Finite Radon Transform) to the tridimensional case. One simple formulation is proposed and it is shown that it is the exact discretization of the... The present work is devoted to the development of the extension of FRT (Finite Radon Transform) to the tridimensional case. One simple formulation is proposed and it is shown that it is the exact discretization of the continuous Discrete Radon Transform. More precisely this is the case when the sampling is given on a regular grid i.e. the continuous function is filtered by the mean of the box function. Relation of this transform with the Discrete Fourier one is given and is for some help in numerical implementation. 展开更多
关键词 RADON TRANSFORM DISCRETE RADON TRANSFORM FRT DISCRETE FOURIER NUMERICAL COMPUTING
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Effect of the drag coefficient on a typhoon wave model 预览
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作者 WANG Zhifeng GONG Yijie +2 位作者 CUI Junnan DONG Sheng WU Kejian 《海洋湖沼学报(英文)》 SCIE CAS CSCD 2019年第6期1795-1804,共10页
The effect of the drag coefficient on a typhoon wave model is investigated.Drag coefficients for Pingtan Island are derived from the progress of nine typhoons using COARE 3.0 software.The wind parameters are obtained ... The effect of the drag coefficient on a typhoon wave model is investigated.Drag coefficients for Pingtan Island are derived from the progress of nine typhoons using COARE 3.0 software.The wind parameters are obtained using the Weather Research and Forecasting model.The simulation of wind agrees well with observations.Typhoon wave fields are then simulated using the third-generation wave model SWAN.The wave model includes exponential and linear growths of the wind input,which determine the wave-growth mode.A triple triangular mesh is adopted with spatial resolution as fine as 100 m nearshore.The SWAN model performs better when using the new drag coefficient rather than the original coefficient. 展开更多
关键词 drag COEFFICIENT TYPHOON WIND TYPHOON WAVE NUMERICAL SIMULATION
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Physical and coupled fully three-dimensional numerical modeling ofpressurized bottom outlet ushing processes in reservoirs 预览
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作者 Ousmane Sawadogo Gerrit R. Basson Simon Schneiderbauer 《国际泥沙研究:英文版》 SCIE 2019年第5期461-474,共14页
Sediment deposition in reservoirs is an important research topic in engineering practice. Reservoir sedimentation has the potential to affect ood levels, drainage for agricultural land, pump station and hydropower ope... Sediment deposition in reservoirs is an important research topic in engineering practice. Reservoir sedimentation has the potential to affect ood levels, drainage for agricultural land, pump station and hydropower operation as well as navigation. This paper describes the development of a coupled fully three-dimensional (3D) numerical model for the prediction of the local sediment ushing scour upstream of the bottom outlet. The presented numerical model solves the Navier-Stokes equations in conjunction with the k- turbulence model which includes both sediment transport and hydrodynamic parameters. The proposed coupled fully 3D numerical model is used to simulate experimental tests based on non-cohesive sediment. The geometric features of the scour hole (temporal and spatial hole devel- opment) upstream of the bottom outlet were reasonably well predicted compared to the experimental data. Furthermore, the velocity eld upstream of the bottom outlet was in good agreement with mea- surements. The proposed numerical model for bottom outlet ushing was, therefore, validated because of its ability to accurately predict the scour hole development during the ushing process. The proposed numerical model can be considered reliable provided that the model is correctly calibrated and set up to re ect the conditions of a particular case study. 展开更多
关键词 Bottom OUTLET COUPLED flow/sediment MODEL SEDIMENT FLUSHING 3D numerical MODEL Packed bed Reservoir
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Determining the effect of relative size of sensor on calibration accuracy of TEM cells 预览
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作者 Yun-Sheng Jiang Cui Meng +3 位作者 Han-Bing Jin Ping Wu Zhi-Qian Xu Liu-Hong Huang 《核技术:英文版》 SCIE CAS CSCD 2019年第6期104-113,共10页
The time-domain calibration coefficient of a D-Dot sensor should be identical across various transverse electromagnetic (TEM) cells to comply with the IEEE Std 1309. However, in our previous calibration experiments, p... The time-domain calibration coefficient of a D-Dot sensor should be identical across various transverse electromagnetic (TEM) cells to comply with the IEEE Std 1309. However, in our previous calibration experiments, poor consistency was observed. The size of D-Dot sensors relative to TEM cells is considered the main reason for this poor consistency. Therefore, this study aims at determining the calibration coefficient of a D-Dot sensor. We calculate the theoretical coefficient as a reference. Practical calibration experiments involve the processing of TEM cells with three different sizes. To observe the response more clearly, corresponding models are constructed and numerical simulations are performed. The numerical simulations and experimental calibration are in good agreement. To determine the calibration accuracy, we quantify the accuracy using the relative error of the calibration coefficient. By comparing the coefficients obtained, it can be concluded that the perturbation error is about 15% when the relative size is over 1/3. Further, the relative size should be less than 1/5 to obtain a relative error below 10%. 展开更多
关键词 D-DOT Electromagnetic SENSOR TIME-DOMAIN CALIBRATION ACCURACY Numerical simulation
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Comparative assessment and analysis of Rortex vortex in swirling jets 预览
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作者 Nan Gui Liang Ge +3 位作者 Peng-xin Cheng Xing-tuan Yang Ji-yuan Tu Sheng-yao Jiang 《水动力学研究与进展:英文版》 SCIE EI CSCD 2019年第3期495-503,共9页
Recently, a new definition, called Rortex, was proposed to quantify the purely rotational motion of fluids. In this work, based on the DNS data, the Rortex is used to assess and visualize the rotational motion and str... Recently, a new definition, called Rortex, was proposed to quantify the purely rotational motion of fluids. In this work, based on the DNS data, the Rortex is used to assess and visualize the rotational motion and structure of the vortex in swirling jets in comparison with other kinds of vortex criteria, including Q , λ2,vorticity and Ω criteria. The Rortex vector,Ω, Q and criteria are found to be better than the vorticity criterion for the vortex core identification. The vector triangle formed by the Rortex R , the nonrotational shear S , and the vorticity R is analyzed to give mechanical explanations, especially of the effect of the non-rotational shear on the rotation of fluids. In addition, the probability density distributions (PDF) of the Rortex R , the nonrotational shear S, and the vorticity R are computed. The peak value of the PDF of the vorticity could be used to explain the pure rigid rotation effect and the combination effects of the rigid rotation and the non?rotational shear. 展开更多
关键词 Swirling flow VORTEX Rortex direct NUMERICAL simulation RIGID ROTATION non-rotational SHEAR
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Deformation characteristics and safety assessment of a high-speed railway induced by undercutting metro tunnel excavation 预览
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作者 Wangping Qian Taiyue Qi +2 位作者 Yunjian Zhao Yizhou Le Haiyang Yi 《岩石力学与岩土工程学报:英文版》 CSCD 2019年第1期88-98,共11页
Stratum deformation(settlement)is a challenging issue in tunnel engineering,especially when construction of metro tunnels has to undercut high-speed railway.For this purpose,we used the FLAC3D software to analyze the ... Stratum deformation(settlement)is a challenging issue in tunnel engineering,especially when construction of metro tunnels has to undercut high-speed railway.For this purpose,we used the FLAC3D software to analyze the stratum settlement characteristics of high-speed railway at different crossing angles intersected by metro tunnel,in terms of ground settlement trough,stratum slip line and irregularity of ballastless tracks.According to the evolution of the stratum settlement at different angle regions,an optimized angle is proposed for the actual project design.In order to reduce the influence of stratum settlement on the safety of high-speed railway,an approach of safety assessment is proposed for the shield engineering undercutting high-speed railway,as per Chinese specifications using numerical results and on-site conditions.A case study is conducted for the shield tunnel section crossing the Wuhan e Guangzhou High-speed Railway between the Guangzhou North Railway Station and the Huacheng Road Station,which represents the first metro tunnel project passing below a high-speed railway in China.A series of measures is taken to ensure the safe excavation of the shield tunnel and the operation of the high-speed railway.The results can provide a technical support for performing a safety evaluation between high-speed railways and metro tunnels. 展开更多
关键词 METRO TUNNEL EXCAVATION High-speed railway SETTLEMENT characteristics Safety assessment Numerical simulation Case application
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Numerical study of a guide-vane-augmented vertical darrieus tidal-currentturbine 预览
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作者 Zhen Liu Zhi-meng Wang +1 位作者 Hong-da Shi Heng-liang Qu 《水动力学研究与进展:英文版》 SCIE EI CSCD 2019年第3期522-530,共9页
It is reported that the augmented vertical axis turbine (VAT) has a better operating performance. A guide-vane type augmentation is proposed in this study, with a simpler outline and a better adaptability to various d... It is reported that the augmented vertical axis turbine (VAT) has a better operating performance. A guide-vane type augmentation is proposed in this study, with a simpler outline and a better adaptability to various directions of the incident water flow, as compared to the duct-type diffuser. A 2?D numerical model based on the computational fluid dynamics software ANSYS-Fluent is established and validated by experimental data. It is found that the guide vanes could narrow the flow path together with the VAT rotor and increase the flow velocity around the blades. The fluctuation of the instantaneous torque output is significantly reduced by using the guide-vane stator. The numerical results indicate that a four blades setup is suitable for the stator and the chord length of the guide vane should be equal to that of the rotor blade. The gap between the stator and the rotor is suggested to be a quarter of the chord length of the rotor blades. The non-zero pitch angle of the guide vane is found to have negative effects on the torque and the power output. The averaged power and torque coefficients for three non-zero directional angles of the incident flow are approximately 30% lower than those for the zero-directional angle. 展开更多
关键词 Tidal current energy VERTICAL axis turbine AUGMENTED rotor GUIDE VANE numerical simulation
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Rotation errors in numerical manifold method and a correction based on large deformation theory
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作者 Ning ZHANG Xu LI +1 位作者 Qinghui JIANG Xingchao LIN 《结构与土木工程前沿:英文版》 EI CSCD 2019年第5期1036-1053,共18页
Numerical manifold method (NMM) is an effective method for simulating block system, however, significant errors are found in its simulation of rotation problems. Three kinds of errors, as volume expansion, stress vibr... Numerical manifold method (NMM) is an effective method for simulating block system, however, significant errors are found in its simulation of rotation problems. Three kinds of errors, as volume expansion, stress vibration, and attenuation of angular velocity, were observed in the original NMM. The first two kind errors are owing to the small deformation assumption and the last one is due to the numerical damping. A large deformation NMM is proposed based on large deformation theory. In this method, the governing equation is derived using Green strain, the large deformation iteration and the open-close iteration are combined, and an updating strategy is proposed. The proposed method is used to analyze block rotation, beam bending, and rock falling problems and the results prove that all three kinds of errors are eliminated in this method. 展开更多
关键词 numerical MANIFOLD method ROTATION large DEFORMATION Green strain open-close ITERATION
Numerical and Experimental Study on Ventilation Panel Models in a Subway Passenger Compartment 预览
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作者 Yu Tao Mingzhi Yang +2 位作者 Bosen Qian Fan Wu Tiantian Wang 《工程(英文)》 2019年第2期329-336,共8页
The internal flow field study of car compartments is an important step in railroad vehicle design and optimization. The flow field profile has a significant impact on the temperature distribution and passenger comfort... The internal flow field study of car compartments is an important step in railroad vehicle design and optimization. The flow field profile has a significant impact on the temperature distribution and passenger comfort level. Experimental studies on flow field can yield accurate results but carry a high time and computational cost. In contrast, the numerical simulation method can yield an internal flow field profile in less time than an experimental study. This study aims to improve the computational efficiency of numerical simulation by adapting two simplified models—the porous media model and the porous jump face model—to study the internal flow field of a railroad car compartment. The results provided by both simplified models are compared with the original numerical simulation model and with experimental data. Based on the results, the porous media model has a better agreement with the original model and with the experimental results. The flow field parameters (temperature and velocity) of the porous media model have relatively small numerical errors, with a maximum numerical error of 4.7%. The difference between the numerical results of the original model and those of the porous media model is less than 1%. By replacing the original numerical simulation model with the porous media model, the flow field of subway car compartments can be calculated with a reduction of about 25% in computing resources, while maintaining good accuracy. 展开更多
关键词 NUMERICAL SIMULATION EXPERIMENT Ventilation PANEL MODEL SUBWAY
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Numerical Investigation of Lid-Driven Deep Cavity with Local Grid Refinement of MRT-LBM 预览
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作者 Dongdong Wan Guichao Wang Songying Chen 《北京理工大学学报:英文版》 EI CAS 2019年第3期536-548,共13页
In the case of lid-driven deep cavity flow, the effects of different resolutions of local grid refinement have been studied in the frame of multiple relaxation times (MRT) lattice Boltzmann method (LBM). In all the ca... In the case of lid-driven deep cavity flow, the effects of different resolutions of local grid refinement have been studied in the frame of multiple relaxation times (MRT) lattice Boltzmann method (LBM). In all the cases, the aspect ratio and Reynolds number are set as 1.5 and 3.200, respectively. First, the applied method is validated by comparing it with two reported works, with which agreements are reached. Then, six separate degrees of local grid refinement at the upper left corner, i.e. purely coarse grid, including 1/64, 1/32, 1/16, 1/8, 1/4 refinements of the lattice number in the width direction have been studied in detail. The results give the following indications:① The refinement degrees lower than 1/8 produce similar results;② For single corner refinement, 1/4 refinement is adequate for clearing the noises in the singularity zone to a large extent;③ New noise around the interface between coarse and fine zones are introduced by local grid refinement. Finally, refinement of entire subzone neighboring the lid is examined to avoid introducing new noises and it has been found effective. 展开更多
关键词 numerical investigation lid-driven DEEP CAVITY local grid REFINEMENT lattice BOLTZMANN method (LBM) multiple relaxation time (MRT)
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Numerical analysis of thermal plasma scrubber for CF4 decomposition
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作者 J KO T H KIM S CHOI 《等离子体科学与技术:英文版》 SCIE EI CAS CSCD 2019年第6期9-14,共6页
CF4 gas emitted in the semiconductor and display manufacturing process is a very harmful greenhouse gas.It must be removed or converted safely due to its extreme toxicity.Although a CF4 decomposition system using a th... CF4 gas emitted in the semiconductor and display manufacturing process is a very harmful greenhouse gas.It must be removed or converted safely due to its extreme toxicity.Although a CF4 decomposition system using a thermal plasma scrubber was commercialized,its removal efficiency is limited.In this work,a numerical analysis of CF4 decomposition in the thermal plasma scrubber was carried out in order to propose an efficient decomposition environment.The decomposition and recombination temperatures of CF4 were analyzed using thermodynamic equilibrium calculations.The chemical reaction of CF4 decomposition into carbon and fluorine gas was considered in this numerical analysis.The injection position and angle of the CF4 were controlled in order to enhance the decomposition rate.The vertical injection of CF4 near the torch exit improved the mixing of the CF4 with the thermal plasma flame.In addition,it was confirmed that the high temperature region expanded due to a vortex generated by strong turbulence in the bottleneck-shaped reactor.As a result,it is revealed that the CF4 injection location and the reactor configuration are the most important factors in improving the decomposition rate. 展开更多
关键词 NUMERICAL simulation DECOMPOSITION CF4 THERMAL PLASMA SCRUBBER
Numerical Simulation of Motor Vehicles' Courtesy Behavior on Crosswalk Based on Car-Following Model 预览
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作者 Baojie Wang Xiangbei Xue Xiaoli Xie 《北京理工大学学报:英文版》 EI CAS 2019年第3期570-576,共7页
In observing driver courtesy towards pedestrians at unsignalized crosswalks, a behavioral model was adopted in a simulation based on the GM Car-Following Model. The SIMI Motion Software was used to extract the vehicle... In observing driver courtesy towards pedestrians at unsignalized crosswalks, a behavioral model was adopted in a simulation based on the GM Car-Following Model. The SIMI Motion Software was used to extract the vehicle operation data from Wenyi South Road and Hanyuan Road in Xi'an City. The parameters of the GM Car-Following Model were calibrated by genetic algorithm. The road simulation environment based on the Car-Following Model was constructed by MATLAB. In the case of no stopping, uniform deceleration avoidance with advance notice, emergency brake avoidance without advance notice, changes such as the displacement of the Car-Following queue, headway, speed, acceleration, and deceleration were analyzed by numerical simulation. The results show that when there is advance notice before the crosswalk, the minimum headway distances of Car1-Car2, Car2-Car3, Car3-Car4 and Car4-Car5 are 7.09 m, 7.38 m, 7.65 m, 7.91 m, and the average rates of change of the headway during deceleration are 0.78 m/s, 0.74 m/s, 0.71 m/s, 0.68 m/s respectively;in the absence of advance notice before the crosswalk, the minimum headway distances of Car1-Car2, Car2-Car3, Car3-Car4 and Car4-Car5 are 7.28 m, 7.75 m, 8.19 m, 8.59 m, and the average rates of change of the headway during deceleration are 1.57 m/s, 1.25 m/s, 1.04 m/s, 0.96 m/s, respectively. Therefore, in order to effectively prevent the occurrence of vehicle rear-end events, it's necessary to set traffic signs and markings on the preceding section of the intersection or road exhibiting behavioral comity. 展开更多
关键词 CAR-FOLLOWING Model CROSSWALK NUMERICAL simulation BEHAVIORAL comity
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Numerical Simulation of Optimization of Mixing Tank for Residue Upgrading Reactor 预览
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作者 Bao Di Tang Xiaojin Zhu Zhenxing 《中国炼油与石油化工:英文版》 SCIE CAS 2019年第2期110-117,共8页
For studying the mixing tank for RMAC (residue upgrading to maximize asphaltene conversion) reactor, the CFD simulation was employed to simulate the flow field in the mixing tank. The dispersion of liquid-liquid phase... For studying the mixing tank for RMAC (residue upgrading to maximize asphaltene conversion) reactor, the CFD simulation was employed to simulate the flow field in the mixing tank. The dispersion of liquid-liquid phase in the mixing tank and the power of turbines were investigated. The simulation results showed that compared with the original doublelayer propeller, the A310-swept double-layer impellers could reduce the liquid heterogeneous degree by 27.5% and the stirring power by 3.25%. The influence of rotation speed on the heterogeneous degree and stirring power was investigated, and the critical rotation speed was obtained. The optimal rotation speed was determined to be 240 r/min. The heterogeneous degree was 0.19 and the minimum stirring power was 10.89 W. By optimizing the impeller selection and process conditions, the overall performance of the mixing tank could be significantly improved. 展开更多
关键词 LIQUID-LIQUID MIXING IMPELLERS numerical simulation critical ROTATION speed
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Progress in molecular docking
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作者 Jiyu Fan Ailing Fu Le Zhang 《中国电气与电子工程前沿:英文版》 CSCD 2019年第2期83-89,共7页
Background:In recent years,since the molecular docking technique can greatly improve the efficiency and reduce the research cost,it has become a key tool in computer-assisted drug design to predict the binding affinit... Background:In recent years,since the molecular docking technique can greatly improve the efficiency and reduce the research cost,it has become a key tool in computer-assisted drug design to predict the binding affinity and analyze the interactive mode.Results:This study introduces the key principles,procedures and the widely-used applications for molecular docking.Also,it compares the commonly used docking applications and recommends which research areas are suitable for them.Lastly,it briefly reviews the latest progress in molecular docking such as the integrated method and deep learning.Conclusion:Limited to the incomplete molecular structure and the shortcomings of the scoring function,current docking applications are not accurate enough to predict the binding affinity.However,we could improve the current molecular docking technique by integrating the big biological data into scoring function. 展开更多
关键词 MOLECULAR DOCKING NUMERICAL analysis OPTIMIZATION data MINING
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