To study the anti-explosion protection effect of polyurea coating on reinforced concrete box girder,two segmental girder specimens were made at a scale of 1:3,numbered as G(without polyurea coating)and PCG(with polyur...To study the anti-explosion protection effect of polyurea coating on reinforced concrete box girder,two segmental girder specimens were made at a scale of 1:3,numbered as G(without polyurea coating)and PCG(with polyurea coating).The failure characteristics and dynamic responses of the specimens were compared through conducting explosion tests.The reliability of the numerical simulation using LS-DYNA software was verified by the test results.The effects of different scaled distances,reinforcement ratios,concrete strengths,coating thicknesses and ranges of polyurea were studied.The results show that the polyurea coating can effectively enhance the anti-explosion performance of the girder.The top plate of middle chamber in specimen G forms an elliptical penetrating hole,while that in specimen PCG only shows a very slight local dent.The peak vertical displacement and residual displacement of PCG decrease by 74.8% and 73.7%,respectively,compared with those of specimen G.For the TNT explosion with small equivalent,the polyurea coating has a more significant protective effect on reducing the size of fracture.With the increase of TNT equivalent,the protective effect of polyurea on reducing girder displacement becomes more significant.The optimal reinforcement ratio,concrete strength,thickness and range of polyurea coating were also drawn.展开更多
Modeling technology has been introduced into software testing field. However, how to carry through the testing modeling effectively is still a difficulty. Based on combination of simulation modeling technology and emb...Modeling technology has been introduced into software testing field. However, how to carry through the testing modeling effectively is still a difficulty. Based on combination of simulation modeling technology and embedded real-time software testing method, the process of simulation testing modeling is studied first. And then, the supporting environment of simulation testing modeling is put forward. Furthermore, an approach of embedded real-time software simulation testing modeling including modeling of cross-linked equipments of system under testing （SUT）, test case, testing scheduling, and testing system service is brought forward. Finally, the formalized description and execution system of testing models are given, with which we can realize real-time, closed loop, mad automated system testing for embedded real-time software.展开更多
As friction, intrinsic steady-state nonlinearity poses a challenging dilemma to the control system of 3-DOF （three degree of freedom） flight simulator, a novel hybrid control strategy of nonlinear PID （proportional...As friction, intrinsic steady-state nonlinearity poses a challenging dilemma to the control system of 3-DOF （three degree of freedom） flight simulator, a novel hybrid control strategy of nonlinear PID （proportionalintegral-derivative） with additional FFC （feed-forward controller） is proposed, and the hardware-in-the-loop simulation results are also given. Based on the description of 3-DOF flight simulator, a novel nonlinear PID theory is well introduced. Then a nonlinear PID controller with additional FFC is designed. Subsequently, the loop structure of 3-DOF flight simulator is also designed. Finally, a series of hardware-in-the-loop simulation experiments are undertaken to verify the feasibility and effectiveness of the proposed nonlinear PID controller with additional FFC for 3-DOF flight simulator.展开更多
为了探寻碰撞参数变化对大豆种子应力分布及形变位移的影响规律,利用Solid Works Simulation对大豆种子碰撞过程进行了模拟分析,获得了大豆种子碰撞过程的应力分布与位移形变及其随时间的变化,并以碰撞速度及接触半径为试验因素,大豆种...为了探寻碰撞参数变化对大豆种子应力分布及形变位移的影响规律,利用Solid Works Simulation对大豆种子碰撞过程进行了模拟分析,获得了大豆种子碰撞过程的应力分布与位移形变及其随时间的变化,并以碰撞速度及接触半径为试验因素,大豆种子碰撞过程的最大应力及最大位移为试验指标,采用正交试验方法,分析参数变化对指标的影响。试验结果表明:对最大应力指标,两因素影响极显著;对最大位移,因素接触半径影响极显著,碰撞速度影响显著。且两指标随着碰撞速度的增大而减小,随着接触半径的增大而先减小而后趋势减缓。研究结果为大豆种子脱粒机的仿真设计和产品研发提供了参考依据。展开更多
The discrete element method (DEM) was used to simulate the flow characteristic and strength characteristic of the conditioned sands in the earth pressure balance (EPB) tunneling. In the laboratory the conditioned sand...The discrete element method (DEM) was used to simulate the flow characteristic and strength characteristic of the conditioned sands in the earth pressure balance (EPB) tunneling. In the laboratory the conditioned sands were reproduced and the slump test and the direct shear test of the conditioned sands were implemented. A DEM equivalent model that can simulate the macro mechanical characteristic of the conditioned sands was proposed,and the corresponding numerical models of the slump test and the shear test were established. By selecting proper DEM model parameters,the errors of the slump values between the simulation results and the test results are in the range of 10.3%-14.3%,and the error of the curves between the shear displacement and the shear stress calculated with the DEM simulation is 4.68%-16.5% compared with that of the laboratory direct shear test. This illustrates that the proposed DEM equivalent model can approximately simulate the mechanical characteristics of the conditioned sands,which provides the basis for further simulation of the interaction between the conditioned soil and the chamber pressure system of the EPB machine.展开更多
We proposed an enhanced image binarization method.The proposed solution incorporates Monte-Carlo simulation into the local thresholding method to address the essential issues with respect to complex background,spatial...We proposed an enhanced image binarization method.The proposed solution incorporates Monte-Carlo simulation into the local thresholding method to address the essential issues with respect to complex background,spatially-changed illumination,and uncertainties of block size in traditional method.The proposed method first partitions the image into square blocks that reflect local characteristics of the image.After image partitioning,each block is binarized using Otsu’s thresholding method.To minimize the influence of the block size and the boundary effect,we incorporate Monte-Carlo simulation into the binarization algorithm.Iterative calculation with varying block sizes during Monte-Carlo simulation generates a probability map,which illustrates the probability of each pixel classified as foreground.By setting a probability threshold,and separating foreground and background of the source image,the final binary image can be obtained.The described method has been tested by benchmark tests.Results demonstrate that the proposed method performs well in dealing with the complex background and illumination condition.展开更多
This paper explores the performances of a finite element simulation including four concrete models applied to a full-scale reinforced concrete beam subjected to blast loading. Field test data has been used to compare ...This paper explores the performances of a finite element simulation including four concrete models applied to a full-scale reinforced concrete beam subjected to blast loading. Field test data has been used to compare model results for each case. The numerical modelling has been, carried out using the suitable code LS-DYNA. This code integrates blast load routine(CONWEP) for the explosive description and four different material models for the concrete including: Karagozian & Case Concrete, Winfrith, Continuous Surface Cap Model and Riedel-Hiermaier-Thoma models, with concrete meshing based on 10, 15, and 20 mm. Six full-scale beams were tested: four of them used for the initial calibration of the numerical model and two more tests at lower scaled distances. For calibration, field data obtained employing pressure and accelerometers transducers were compared with the results derived from the numerical simulation. Damage surfaces and the shape of rupture in the beams have been used as references for comparison. Influence of the meshing on accelerations has been put in evidence and for some models the shape and size of the damage in the beams produced maximum differences around 15%. In all cases, the variations between material and mesh models are shown and discussed.展开更多
基金the Natural Science Foundation of Jiangsu Province(Grant No.BK20200494)China Postdoctoral Science Foundation(Grant No.2021M701725)+3 种基金Jiangsu Postdoctoral Research Funding Program(Grant No.2021K522C)Fundamental Research Funds for the Central Universities(Grant No.30919011246)National Natural Science Foundation of China(Grant No.52278188)Natural Science Foundation of Jiangsu Province(Grant No.BK20211196)。
文摘To study the anti-explosion protection effect of polyurea coating on reinforced concrete box girder,two segmental girder specimens were made at a scale of 1:3,numbered as G(without polyurea coating)and PCG(with polyurea coating).The failure characteristics and dynamic responses of the specimens were compared through conducting explosion tests.The reliability of the numerical simulation using LS-DYNA software was verified by the test results.The effects of different scaled distances,reinforcement ratios,concrete strengths,coating thicknesses and ranges of polyurea were studied.The results show that the polyurea coating can effectively enhance the anti-explosion performance of the girder.The top plate of middle chamber in specimen G forms an elliptical penetrating hole,while that in specimen PCG only shows a very slight local dent.The peak vertical displacement and residual displacement of PCG decrease by 74.8% and 73.7%,respectively,compared with those of specimen G.For the TNT explosion with small equivalent,the polyurea coating has a more significant protective effect on reducing the size of fracture.With the increase of TNT equivalent,the protective effect of polyurea on reducing girder displacement becomes more significant.The optimal reinforcement ratio,concrete strength,thickness and range of polyurea coating were also drawn.
文摘Modeling technology has been introduced into software testing field. However, how to carry through the testing modeling effectively is still a difficulty. Based on combination of simulation modeling technology and embedded real-time software testing method, the process of simulation testing modeling is studied first. And then, the supporting environment of simulation testing modeling is put forward. Furthermore, an approach of embedded real-time software simulation testing modeling including modeling of cross-linked equipments of system under testing （SUT）, test case, testing scheduling, and testing system service is brought forward. Finally, the formalized description and execution system of testing models are given, with which we can realize real-time, closed loop, mad automated system testing for embedded real-time software.
基金the National Natural Science Foundation of China (60604009)Aeronautical Science Foundationof China(2006ZC51039)Beijing NOVA Program (2007A017).
文摘As friction, intrinsic steady-state nonlinearity poses a challenging dilemma to the control system of 3-DOF （three degree of freedom） flight simulator, a novel hybrid control strategy of nonlinear PID （proportionalintegral-derivative） with additional FFC （feed-forward controller） is proposed, and the hardware-in-the-loop simulation results are also given. Based on the description of 3-DOF flight simulator, a novel nonlinear PID theory is well introduced. Then a nonlinear PID controller with additional FFC is designed. Subsequently, the loop structure of 3-DOF flight simulator is also designed. Finally, a series of hardware-in-the-loop simulation experiments are undertaken to verify the feasibility and effectiveness of the proposed nonlinear PID controller with additional FFC for 3-DOF flight simulator.
文摘为了探寻碰撞参数变化对大豆种子应力分布及形变位移的影响规律,利用Solid Works Simulation对大豆种子碰撞过程进行了模拟分析,获得了大豆种子碰撞过程的应力分布与位移形变及其随时间的变化,并以碰撞速度及接触半径为试验因素,大豆种子碰撞过程的最大应力及最大位移为试验指标,采用正交试验方法,分析参数变化对指标的影响。试验结果表明:对最大应力指标,两因素影响极显著;对最大位移,因素接触半径影响极显著,碰撞速度影响显著。且两指标随着碰撞速度的增大而减小,随着接触半径的增大而先减小而后趋势减缓。研究结果为大豆种子脱粒机的仿真设计和产品研发提供了参考依据。
基金Project (2007CB714006) supported by the National Basic Research Program of China
文摘The discrete element method (DEM) was used to simulate the flow characteristic and strength characteristic of the conditioned sands in the earth pressure balance (EPB) tunneling. In the laboratory the conditioned sands were reproduced and the slump test and the direct shear test of the conditioned sands were implemented. A DEM equivalent model that can simulate the macro mechanical characteristic of the conditioned sands was proposed,and the corresponding numerical models of the slump test and the shear test were established. By selecting proper DEM model parameters,the errors of the slump values between the simulation results and the test results are in the range of 10.3%-14.3%,and the error of the curves between the shear displacement and the shear stress calculated with the DEM simulation is 4.68%-16.5% compared with that of the laboratory direct shear test. This illustrates that the proposed DEM equivalent model can approximately simulate the mechanical characteristics of the conditioned sands,which provides the basis for further simulation of the interaction between the conditioned soil and the chamber pressure system of the EPB machine.
基金Project(2018YFC1505401)supported by the National Key R&D Program of ChinaProject(41702310)supported by the National Natural Science Foundation of China+1 种基金Project(SKLGP2017K014)supported by the Foundation of State Key Laboratory of Geohazard Prevention and Geo-environment Protection,ChinaProject(2018JJ3644)supported by the Natural Science Foundation of Hunan Province,China
文摘We proposed an enhanced image binarization method.The proposed solution incorporates Monte-Carlo simulation into the local thresholding method to address the essential issues with respect to complex background,spatially-changed illumination,and uncertainties of block size in traditional method.The proposed method first partitions the image into square blocks that reflect local characteristics of the image.After image partitioning,each block is binarized using Otsu’s thresholding method.To minimize the influence of the block size and the boundary effect,we incorporate Monte-Carlo simulation into the binarization algorithm.Iterative calculation with varying block sizes during Monte-Carlo simulation generates a probability map,which illustrates the probability of each pixel classified as foreground.By setting a probability threshold,and separating foreground and background of the source image,the final binary image can be obtained.The described method has been tested by benchmark tests.Results demonstrate that the proposed method performs well in dealing with the complex background and illumination condition.
基金This research has been conducted under SEGTRANS project,funded by the Centre for Industrial Technological Development(CDTI,Government of Spain).
文摘This paper explores the performances of a finite element simulation including four concrete models applied to a full-scale reinforced concrete beam subjected to blast loading. Field test data has been used to compare model results for each case. The numerical modelling has been, carried out using the suitable code LS-DYNA. This code integrates blast load routine(CONWEP) for the explosive description and four different material models for the concrete including: Karagozian & Case Concrete, Winfrith, Continuous Surface Cap Model and Riedel-Hiermaier-Thoma models, with concrete meshing based on 10, 15, and 20 mm. Six full-scale beams were tested: four of them used for the initial calibration of the numerical model and two more tests at lower scaled distances. For calibration, field data obtained employing pressure and accelerometers transducers were compared with the results derived from the numerical simulation. Damage surfaces and the shape of rupture in the beams have been used as references for comparison. Influence of the meshing on accelerations has been put in evidence and for some models the shape and size of the damage in the beams produced maximum differences around 15%. In all cases, the variations between material and mesh models are shown and discussed.
