Test is one of methods to acquire human-seat pressure distribution in driving,with the deficiency of being uneasy to obtain the stress information of soft tissue inside human body and the sheer force of interface betw...Test is one of methods to acquire human-seat pressure distribution in driving,with the deficiency of being uneasy to obtain the stress information of soft tissue inside human body and the sheer force of interface between human and seat,which can be obtained by simulation.But current simulation method focuses mainly on calculation itself other than combining it with posture prediction and cab packaging parameters,which cause it difficult to acquire accurate pressure calculation results without accurate posture of human body,and make it almost meaningless to design optimization.Therefore,a human body geometric model with posture change capability is built and linked up with Cascade Prediction Model(CPM),which takes cab packaging parameters as inputs.A detailed finite element model of driver human body is constructed and used to conduct the driver-seat interaction simulation between human body and seat.Good accordance of pressure distribution is observed between simulation and test,which validates the simulation.In addition to the distribution pattern,curves on key sections are used to analyze the pressure and shear stress on the seat surface,as well as soft tissue stress inside human body.The simulation shows that the maximum stress of buttocks locates under the ischial tuberosity,and the maximum stress of trunk occurs near the scapula posterior and the lower waist.These are the places where fatigue usually occurs.The maximum pressure of seat appears at the driver-seat contact area corresponding to the driver's maximum skin tissue stress.In order to guide the seat design and cab packaging and study the influence of posture to pressure distribution,finite element models for different levels of cab packaging parameters are created by using CPM.The pressure distributions are calculated and their tendencies varying with cab packaging parameters are obtained.The method presented provides a new way to accurately simulate the interaction between driver human body and seat,and to guide the seat design and cab packaging so as to improve seating comfort.展开更多
The steel turnout is one of the key components in the medium–low-speed maglev line system.However,the vehicle under active control is prone to vehicle–turnout coupled vibration,and thus,it is necessary to identify t...The steel turnout is one of the key components in the medium–low-speed maglev line system.However,the vehicle under active control is prone to vehicle–turnout coupled vibration,and thus,it is necessary to identify the vibration characteristics of this coupled system through field tests.To this end,dynamic performance tests were conducted on a vehicle–turnout coupled system in a medium–low-speed maglev test line.Firstly,the dynamic response data of the coupled system under various operating conditions were obtained.Then,the natural vibration characteristics of the turnout were analysed using the free attenuation method and the finite element method,indicating a good agreement between the simulation results and the measured results;the acceleration response characteristics of the coupled system were analysed in detail,and the ride quality of the vehicle was assessed by Sperling index.Finally,the frequency distribution characteristics of the coupled system were discussed.All these test results could provide references for model validation and optimized design of medium–low-speed maglev transport systems.展开更多
Prior austenite grain size dependence of the low temperature impact toughness has been addressed in the bainitic weld metals by in situ observations.Usually,decreasing the grain size is the only approach by which both...Prior austenite grain size dependence of the low temperature impact toughness has been addressed in the bainitic weld metals by in situ observations.Usually,decreasing the grain size is the only approach by which both the strength and the toughness of a steel are increased.However,low carbon bainitic steel with small grain size shows a weakening of the low temperature impact toughness in this study.By direct tracking of the morphological evolution during phase transformation,it is found that large austenite grain size dominates the nucleation of intragranular acicular ferrite,whereas small austenite grain size leads to grain boundary nucleation of bainite.This kinetics information will contribute to meet the increasing low temperature toughness requirement of weld metals for the storage tanks and offshore structures.展开更多
Aiming at the problem that indoor positioning technology based on wireless ultra-wideband pulse technology is susceptible to non-line-of-sight effects and multipath effects in confined spaces and weak signal environme...Aiming at the problem that indoor positioning technology based on wireless ultra-wideband pulse technology is susceptible to non-line-of-sight effects and multipath effects in confined spaces and weak signal environments,a high-precision positioning system based on UWB and IMU in a confined environment is designed.The STM32 chip is used as the main control,and the data information of IMU and UWB is fused by the fusion filtering algorithm.Finally,the real-time information of the positioning is transmitted to the host computer and the cloud.The experimental results show that the positioning accuracy and positioning stability of the system have been improved in the non-line-of-sight case of closed environment.The system has high positioning accuracy in a closed environment,and the components used are consumer-grade,which has strong practicability.展开更多
To address the issue of inadequate detection performance for small and mediumsized densely packed vessels in ship target detection,this paper proposes an improved Single Shot Multibox Detector(SSD)model to achieve mor...To address the issue of inadequate detection performance for small and mediumsized densely packed vessels in ship target detection,this paper proposes an improved Single Shot Multibox Detector(SSD)model to achieve more accurate detection.The algorithm redesigns the anchor boxes to fit the ship target detection dataset better and integrates the Squeeze-and-Excitation(SE)module into the Visual Geometry Group(VGG)network to enhance the channel features of the input feature maps.Additionally,the network's ability to perceive and represent important features is further enhanced by introducing the Convolutional Block Attention Module(CBAM),which is responsible for channel and spatial attention mechanisms.Finally,the feature pyramid module is employed to fuse six layers of features from the original network,thereby improving the SSD network's capability to detect small and occluded densely packed vessel targets.The experimental results show that the model's target recognition ability for fishing vessels improved from 58.07%to 65.87%;for patrol boats,the ability increased from 94.6%to 96.03%;and for inflatable boats,it rose from 72.08%to 74.93%.The overall mean Average Precision(mAP)also increased from the original model's 80.04%to 81.22%.Additionally,by clustering prior boxes,more suitable prior boxes for vessel detection were obtained,enhancing the model's perception capabilities for both large and small vessels.展开更多
A general method is developed for optimal application of dampers and actuators by installing them at optimal location on seismic-resistant structures.The study includes development of a statistical criterion,formulati...A general method is developed for optimal application of dampers and actuators by installing them at optimal location on seismic-resistant structures.The study includes development of a statistical criterion,formulation of a general optimization problem and establishment of a solution procedure.Numerical analysis of the seismic response in time-history of controlled structures is used to verify the proposed method for optimal device application and to demonstrate the effectiveness of seismic response control with optimal device location.This study shows that the proposed method for the optimal device application is simple and general,and that the optimally applied dampers and actuators are very efficient for seismic response reduction.展开更多
In order to analyze the normal deviatoric stress that viscous-elastic fluid acting on the residual oil under the situation of different flooding conditions and different permeabilities, Viscous-elastic fluid flow equa...In order to analyze the normal deviatoric stress that viscous-elastic fluid acting on the residual oil under the situation of different flooding conditions and different permeabilities, Viscous-elastic fluid flow equation is established in the micro pore by choosing the continuity equation, motion equation and the upper-convected Maxwell constitutive equation, the flow field is computed by using numerical analysis, the forces that driving fluid acting on the residual oil in micro pore are got, and the influence of flooding conditions, pore width and viscous-elasticity of driving fluid on force is compared and analyzed. The results show that: the more viscous-elasticity of driving fluid increases, the greater the normal deviatoric stress acting on the residual oil increases;using constant pressure gradient flooding, the lager the pore width is, the greater normal deviatoric stress acting on the residual oil will be.展开更多
Partial agglomeration is a major problem in fluidized beds. A chaotic analytical method based on the phase-plane invariant of the pressure fluctuations in the fluidized beds has been used to warn of agglomeration at a...Partial agglomeration is a major problem in fluidized beds. A chaotic analytical method based on the phase-plane invariant of the pressure fluctuations in the fluidized beds has been used to warn of agglomeration at an early stage. Cold tests （no combustion） and hot tests （combustion） in fluidized beds show that the phase-plane invariant of the pressure fluctuations can distinguish the dynamic behavior of fluidized beds with different flow rates in cold tests. With combustion, when the flow rate was kept constant, agglomeration was detected very early by looking at the phase-plane invariant. The phase-plane invariant can be used to distinguish changes in fluidized beds due to changes in the flow rate, agglomeration, or various other factors. Therefore, this reliable agglomeration early warning system can be used for better control of circulating fluidized beds.展开更多
To clarify the corrosion behavior of Ni-based hard facing alloy Colmonoy 56 and the preferential dissolution detail at the micrometer scale,the microstructure and the elemental distribution of a rod were analyzed,foll...To clarify the corrosion behavior of Ni-based hard facing alloy Colmonoy 56 and the preferential dissolution detail at the micrometer scale,the microstructure and the elemental distribution of a rod were analyzed,followed with the polarization measurement in aqueous solution with different p H and Na Cl concentrations.This rod has Fe-,Si-,and Cr-solutioned[Ni]matrix with heterogeneously dispersed secondary phases of Cr_(23)C_(6),CrB,Cr_(2)B,and Cr_(5)B_(3).The polarization curve largely changed with different p H:active in acid solution and passive in neutral and alkaline solution.The strongest passivation appeared at p H=11.Cl^(-)promoted the corrosion attack to the[Ni]matrix.In the case of pH=11,Cl^(-)caused the fast climb of anodic current from passivation at a less noble potential.Preferential dissolution of the[Ni]matrix occurred in most solutions,except in the case of pH=14 without Na Cl,in which the secondary phases preferably dissolved.展开更多
基金supported by 2011 Scientific Frontier and Interdiscipline Reformation Project of Jilin University,China(Grant No.450060445100)
文摘Test is one of methods to acquire human-seat pressure distribution in driving,with the deficiency of being uneasy to obtain the stress information of soft tissue inside human body and the sheer force of interface between human and seat,which can be obtained by simulation.But current simulation method focuses mainly on calculation itself other than combining it with posture prediction and cab packaging parameters,which cause it difficult to acquire accurate pressure calculation results without accurate posture of human body,and make it almost meaningless to design optimization.Therefore,a human body geometric model with posture change capability is built and linked up with Cascade Prediction Model(CPM),which takes cab packaging parameters as inputs.A detailed finite element model of driver human body is constructed and used to conduct the driver-seat interaction simulation between human body and seat.Good accordance of pressure distribution is observed between simulation and test,which validates the simulation.In addition to the distribution pattern,curves on key sections are used to analyze the pressure and shear stress on the seat surface,as well as soft tissue stress inside human body.The simulation shows that the maximum stress of buttocks locates under the ischial tuberosity,and the maximum stress of trunk occurs near the scapula posterior and the lower waist.These are the places where fatigue usually occurs.The maximum pressure of seat appears at the driver-seat contact area corresponding to the driver's maximum skin tissue stress.In order to guide the seat design and cab packaging and study the influence of posture to pressure distribution,finite element models for different levels of cab packaging parameters are created by using CPM.The pressure distributions are calculated and their tendencies varying with cab packaging parameters are obtained.The method presented provides a new way to accurately simulate the interaction between driver human body and seat,and to guide the seat design and cab packaging so as to improve seating comfort.
基金This work was supported by the National Natural Science Foundation of China(Grant No.51875483)the Independently Funded Research Project of State Key Laboratory of Traction Power(Grant Nos.2020TPL-T01 and 2020TPL-T04).
文摘The steel turnout is one of the key components in the medium–low-speed maglev line system.However,the vehicle under active control is prone to vehicle–turnout coupled vibration,and thus,it is necessary to identify the vibration characteristics of this coupled system through field tests.To this end,dynamic performance tests were conducted on a vehicle–turnout coupled system in a medium–low-speed maglev test line.Firstly,the dynamic response data of the coupled system under various operating conditions were obtained.Then,the natural vibration characteristics of the turnout were analysed using the free attenuation method and the finite element method,indicating a good agreement between the simulation results and the measured results;the acceleration response characteristics of the coupled system were analysed in detail,and the ride quality of the vehicle was assessed by Sperling index.Finally,the frequency distribution characteristics of the coupled system were discussed.All these test results could provide references for model validation and optimized design of medium–low-speed maglev transport systems.
文摘Prior austenite grain size dependence of the low temperature impact toughness has been addressed in the bainitic weld metals by in situ observations.Usually,decreasing the grain size is the only approach by which both the strength and the toughness of a steel are increased.However,low carbon bainitic steel with small grain size shows a weakening of the low temperature impact toughness in this study.By direct tracking of the morphological evolution during phase transformation,it is found that large austenite grain size dominates the nucleation of intragranular acicular ferrite,whereas small austenite grain size leads to grain boundary nucleation of bainite.This kinetics information will contribute to meet the increasing low temperature toughness requirement of weld metals for the storage tanks and offshore structures.
文摘Aiming at the problem that indoor positioning technology based on wireless ultra-wideband pulse technology is susceptible to non-line-of-sight effects and multipath effects in confined spaces and weak signal environments,a high-precision positioning system based on UWB and IMU in a confined environment is designed.The STM32 chip is used as the main control,and the data information of IMU and UWB is fused by the fusion filtering algorithm.Finally,the real-time information of the positioning is transmitted to the host computer and the cloud.The experimental results show that the positioning accuracy and positioning stability of the system have been improved in the non-line-of-sight case of closed environment.The system has high positioning accuracy in a closed environment,and the components used are consumer-grade,which has strong practicability.
基金funded by Changzhou technology project(CZ20230025)Natural science foundation of jiangsu province(BK20150247).
文摘To address the issue of inadequate detection performance for small and mediumsized densely packed vessels in ship target detection,this paper proposes an improved Single Shot Multibox Detector(SSD)model to achieve more accurate detection.The algorithm redesigns the anchor boxes to fit the ship target detection dataset better and integrates the Squeeze-and-Excitation(SE)module into the Visual Geometry Group(VGG)network to enhance the channel features of the input feature maps.Additionally,the network's ability to perceive and represent important features is further enhanced by introducing the Convolutional Block Attention Module(CBAM),which is responsible for channel and spatial attention mechanisms.Finally,the feature pyramid module is employed to fuse six layers of features from the original network,thereby improving the SSD network's capability to detect small and occluded densely packed vessel targets.The experimental results show that the model's target recognition ability for fishing vessels improved from 58.07%to 65.87%;for patrol boats,the ability increased from 94.6%to 96.03%;and for inflatable boats,it rose from 72.08%to 74.93%.The overall mean Average Precision(mAP)also increased from the original model's 80.04%to 81.22%.Additionally,by clustering prior boxes,more suitable prior boxes for vessel detection were obtained,enhancing the model's perception capabilities for both large and small vessels.
基金the National Science Foundation under grant CMS 9903136
文摘A general method is developed for optimal application of dampers and actuators by installing them at optimal location on seismic-resistant structures.The study includes development of a statistical criterion,formulation of a general optimization problem and establishment of a solution procedure.Numerical analysis of the seismic response in time-history of controlled structures is used to verify the proposed method for optimal device application and to demonstrate the effectiveness of seismic response control with optimal device location.This study shows that the proposed method for the optimal device application is simple and general,and that the optimally applied dampers and actuators are very efficient for seismic response reduction.
文摘In order to analyze the normal deviatoric stress that viscous-elastic fluid acting on the residual oil under the situation of different flooding conditions and different permeabilities, Viscous-elastic fluid flow equation is established in the micro pore by choosing the continuity equation, motion equation and the upper-convected Maxwell constitutive equation, the flow field is computed by using numerical analysis, the forces that driving fluid acting on the residual oil in micro pore are got, and the influence of flooding conditions, pore width and viscous-elasticity of driving fluid on force is compared and analyzed. The results show that: the more viscous-elasticity of driving fluid increases, the greater the normal deviatoric stress acting on the residual oil increases;using constant pressure gradient flooding, the lager the pore width is, the greater normal deviatoric stress acting on the residual oil will be.
基金the Ishikawajima-Harima Heavy Industries Co., Ltd., Japan
文摘Partial agglomeration is a major problem in fluidized beds. A chaotic analytical method based on the phase-plane invariant of the pressure fluctuations in the fluidized beds has been used to warn of agglomeration at an early stage. Cold tests （no combustion） and hot tests （combustion） in fluidized beds show that the phase-plane invariant of the pressure fluctuations can distinguish the dynamic behavior of fluidized beds with different flow rates in cold tests. With combustion, when the flow rate was kept constant, agglomeration was detected very early by looking at the phase-plane invariant. The phase-plane invariant can be used to distinguish changes in fluidized beds due to changes in the flow rate, agglomeration, or various other factors. Therefore, this reliable agglomeration early warning system can be used for better control of circulating fluidized beds.
文摘To clarify the corrosion behavior of Ni-based hard facing alloy Colmonoy 56 and the preferential dissolution detail at the micrometer scale,the microstructure and the elemental distribution of a rod were analyzed,followed with the polarization measurement in aqueous solution with different p H and Na Cl concentrations.This rod has Fe-,Si-,and Cr-solutioned[Ni]matrix with heterogeneously dispersed secondary phases of Cr_(23)C_(6),CrB,Cr_(2)B,and Cr_(5)B_(3).The polarization curve largely changed with different p H:active in acid solution and passive in neutral and alkaline solution.The strongest passivation appeared at p H=11.Cl^(-)promoted the corrosion attack to the[Ni]matrix.In the case of pH=11,Cl^(-)caused the fast climb of anodic current from passivation at a less noble potential.Preferential dissolution of the[Ni]matrix occurred in most solutions,except in the case of pH=14 without Na Cl,in which the secondary phases preferably dissolved.
