In the network for data transmission using CMT,there are multiple paths to choose,and the time delay of each path is not the same,there is a certain issue packet out-of-order.This article studied and analyzed the pack...In the network for data transmission using CMT,there are multiple paths to choose,and the time delay of each path is not the same,there is a certain issue packet out-of-order.This article studied and analyzed the packet transmission in the sender,for each path assigned specific packet sequence number,in order to reduce the random sequence problem,improve the efficiency of network transmission.In the network for data transmission using CMT,there are multiple paths to choose,and the time delay of each path is not the same,there is a certain issue packet out-of-order.This article studied and analyzed the packet transmission in the sender,for each path assigned specific packet sequence number,in order to reduce the random sequence problem,improve the efficiency of network transmission.展开更多
Operational transfer path analysis(OTPA)is an advanced vibration and noise transfer path identification and contribution evaluation method.However,the application of OTPA to rail transit vehicles considers only the ex...Operational transfer path analysis(OTPA)is an advanced vibration and noise transfer path identification and contribution evaluation method.However,the application of OTPA to rail transit vehicles considers only the excitation amplitude and ignores the influence of the excitation phase.This study considers the influence of the excitation amplitude and phase,and analyzes the contribution of the secondary suspension path to the floor vibration when the metro vehicle runs at 60 km/h,using an analysis based on the OTPA method.The results show that the vertical direction of the anti-rolling torsion bar area provides the maximum contribution to the floor vibration,with a contribution of 22.1%,followed by the longitudinal vibration of the air spring area,with a contribution of 17.1%.Based on the contribution analysis,a transfer path optimization scheme is proposed,which may provide a reference for the optimization of the transfer path of metro vehicles in the future.展开更多
Passengers’demands for riding comfort have been getting higher and higher as the high-speed railway develops.Scientific methods to analyze the interior noise of the high-speed train are needed and the operational tra...Passengers’demands for riding comfort have been getting higher and higher as the high-speed railway develops.Scientific methods to analyze the interior noise of the high-speed train are needed and the operational transfer path analysis(OTPA)method provides a theoretical basis and guidance for the noise control of the train and overcomes the shortcomings of the traditional method,which has high test efficiency and can be carried out during the working state of the targeted machine.The OTPA model is established from the aspects of“path reference point-target point”and“sound source reference point-target point”.As for the mechanism of the noise transmission path,an assumption is made that the direct sound propagation is ignored,and the symmetric sound source and the symmetric path are merged.Using the operational test data and the OTPA method,combined with the results of spherical array sound source identification,the path contribution and sound source contribution of the interior noise are analyzed,respectively,from aspects of the total value and spectrum.The results show that the OTPA conforms to the calculation results of the spherical array sound source identification.At low speed,the contribution of the floor path and the contribution of the bogie sources are dominant.When the speed is greater than 300 km/h,the contribution of the roof path is dominant.Moreover,for the carriage with a pantograph,the lifted pantograph is an obvious source.The noise from the exterior sources of the train transfer into the interior mainly through the form of structural excitation,and the contribution of air excitation is non-significant.Certain analyses of train parts provide guides for the interior noise control.展开更多
Taking swash plate axial piston pump as the research object,the mechanism of fluid vibration and transfer rule are analyzed.The pump shell can be assumed as the ultimate recipient of vibration transmission,the path mo...Taking swash plate axial piston pump as the research object,the mechanism of fluid vibration and transfer rule are analyzed.The pump shell can be assumed as the ultimate recipient of vibration transmission,the path model and differential equations from the fluid to the shell are established.The parameters of the path model are determined by the simulation software,and the mathematical model is solved by the simulation software.And time/frequency domain analysis of vibration acceleration of shell is presented.Based on the different influence of various parameters in the transfer path model on transfer characteristics and vibrational recipients,the time-varying parameters are studied by using sensitivity analysis theory,and the influence of the structural parameters on the vibration characteristics of vibration subject is quantitatively analyzed.The research in the paper provides theoretical basis for vibration analysis and structure parameter optimization of axial piston pump.展开更多
Noise is one of the key issues in the operation of high-speed railways, with sound source localisation and its transfer path as the two major aspects. This study investigates both the exterior and interior sound sourc...Noise is one of the key issues in the operation of high-speed railways, with sound source localisation and its transfer path as the two major aspects. This study investigates both the exterior and interior sound source distribution of a high-speed train and presents a method for performing the contribution analysis of airborne sound with regard to the interior noise. First, both exterior and interior sound source locations of the high-speed train are identified through in-situ measurements. Second, the sound source contribution for di erent regions of the train and the relationships between the exterior and interior noises are analysed. Third, a method for conducting the contribution analysis of airborne sound with regard to the interior noise of the high-speed train is described. Lastly, a case study on the sidewall area is carried out, and the contribution of airborne sound to the interior noise of this area is obtained. The results show that, when the high-speed train runs at 310 km/h, dominant exterior sound sources are located in the bogie and pantograph regions, while main interior sound sources are located at the sidewall and roof. The interior noise, the bogie area noise and the sound source at the middle of the coach exhibit very similar rates of increase with increasing train speed. For the selected sidewall area, structure-borne sound dominates in most of the 1/3 octave bands.展开更多
为解决汽车车身结构开发阶段中传统的车身噪声传递函数技术计算复杂、优化效率低下的问题,通过卷积神经网络建立动态激励下车内驾驶位置的噪声传函响应(Noise Transfer Function,NTF)的预测模型,以车身不同结构点动刚度(Dynamic Stiffne...为解决汽车车身结构开发阶段中传统的车身噪声传递函数技术计算复杂、优化效率低下的问题,通过卷积神经网络建立动态激励下车内驾驶位置的噪声传函响应(Noise Transfer Function,NTF)的预测模型,以车身不同结构点动刚度(Dynamic Stiffness,DS)为特征对应模型输入,车内驾驶员人耳位置NTF为输出,训练底盘前悬架摆臂和后悬架减震器接附点分别受到激励时,车内驾驶位的NTF预测模型,最后通过仿真计算结果对比,验证模型的预测性能。展开更多
文摘In the network for data transmission using CMT,there are multiple paths to choose,and the time delay of each path is not the same,there is a certain issue packet out-of-order.This article studied and analyzed the packet transmission in the sender,for each path assigned specific packet sequence number,in order to reduce the random sequence problem,improve the efficiency of network transmission.In the network for data transmission using CMT,there are multiple paths to choose,and the time delay of each path is not the same,there is a certain issue packet out-of-order.This article studied and analyzed the packet transmission in the sender,for each path assigned specific packet sequence number,in order to reduce the random sequence problem,improve the efficiency of network transmission.
基金Supported by National Natural Science Foundation of China(Grant Nos.U1934203,U1734201)Sichuan Science and Technology Program(Grant No.2020YJ0254)Fundamental Research Funds for the State Key Laboratory of Traction Power(Grant No.2019-Q02).
文摘Operational transfer path analysis(OTPA)is an advanced vibration and noise transfer path identification and contribution evaluation method.However,the application of OTPA to rail transit vehicles considers only the excitation amplitude and ignores the influence of the excitation phase.This study considers the influence of the excitation amplitude and phase,and analyzes the contribution of the secondary suspension path to the floor vibration when the metro vehicle runs at 60 km/h,using an analysis based on the OTPA method.The results show that the vertical direction of the anti-rolling torsion bar area provides the maximum contribution to the floor vibration,with a contribution of 22.1%,followed by the longitudinal vibration of the air spring area,with a contribution of 17.1%.Based on the contribution analysis,a transfer path optimization scheme is proposed,which may provide a reference for the optimization of the transfer path of metro vehicles in the future.
文摘Passengers’demands for riding comfort have been getting higher and higher as the high-speed railway develops.Scientific methods to analyze the interior noise of the high-speed train are needed and the operational transfer path analysis(OTPA)method provides a theoretical basis and guidance for the noise control of the train and overcomes the shortcomings of the traditional method,which has high test efficiency and can be carried out during the working state of the targeted machine.The OTPA model is established from the aspects of“path reference point-target point”and“sound source reference point-target point”.As for the mechanism of the noise transmission path,an assumption is made that the direct sound propagation is ignored,and the symmetric sound source and the symmetric path are merged.Using the operational test data and the OTPA method,combined with the results of spherical array sound source identification,the path contribution and sound source contribution of the interior noise are analyzed,respectively,from aspects of the total value and spectrum.The results show that the OTPA conforms to the calculation results of the spherical array sound source identification.At low speed,the contribution of the floor path and the contribution of the bogie sources are dominant.When the speed is greater than 300 km/h,the contribution of the roof path is dominant.Moreover,for the carriage with a pantograph,the lifted pantograph is an obvious source.The noise from the exterior sources of the train transfer into the interior mainly through the form of structural excitation,and the contribution of air excitation is non-significant.Certain analyses of train parts provide guides for the interior noise control.
基金Supported by the National Nature Science Foundation of China(No.51705445)General Project of Natural Science Foundation of Hebei Province(No.E2020203052)Youth Fund Project of Scientific Research Project of Hebei University(No.QN202013)。
文摘Taking swash plate axial piston pump as the research object,the mechanism of fluid vibration and transfer rule are analyzed.The pump shell can be assumed as the ultimate recipient of vibration transmission,the path model and differential equations from the fluid to the shell are established.The parameters of the path model are determined by the simulation software,and the mathematical model is solved by the simulation software.And time/frequency domain analysis of vibration acceleration of shell is presented.Based on the different influence of various parameters in the transfer path model on transfer characteristics and vibrational recipients,the time-varying parameters are studied by using sensitivity analysis theory,and the influence of the structural parameters on the vibration characteristics of vibration subject is quantitatively analyzed.The research in the paper provides theoretical basis for vibration analysis and structure parameter optimization of axial piston pump.
基金Supported by National Key R&D Program of China(Grant No.2016YFE0205200)National Natural Science Foundation of China(Grant No.U1834201)
文摘Noise is one of the key issues in the operation of high-speed railways, with sound source localisation and its transfer path as the two major aspects. This study investigates both the exterior and interior sound source distribution of a high-speed train and presents a method for performing the contribution analysis of airborne sound with regard to the interior noise. First, both exterior and interior sound source locations of the high-speed train are identified through in-situ measurements. Second, the sound source contribution for di erent regions of the train and the relationships between the exterior and interior noises are analysed. Third, a method for conducting the contribution analysis of airborne sound with regard to the interior noise of the high-speed train is described. Lastly, a case study on the sidewall area is carried out, and the contribution of airborne sound to the interior noise of this area is obtained. The results show that, when the high-speed train runs at 310 km/h, dominant exterior sound sources are located in the bogie and pantograph regions, while main interior sound sources are located at the sidewall and roof. The interior noise, the bogie area noise and the sound source at the middle of the coach exhibit very similar rates of increase with increasing train speed. For the selected sidewall area, structure-borne sound dominates in most of the 1/3 octave bands.
文摘为解决汽车车身结构开发阶段中传统的车身噪声传递函数技术计算复杂、优化效率低下的问题,通过卷积神经网络建立动态激励下车内驾驶位置的噪声传函响应(Noise Transfer Function,NTF)的预测模型,以车身不同结构点动刚度(Dynamic Stiffness,DS)为特征对应模型输入,车内驾驶员人耳位置NTF为输出,训练底盘前悬架摆臂和后悬架减震器接附点分别受到激励时,车内驾驶位的NTF预测模型,最后通过仿真计算结果对比,验证模型的预测性能。
