文章根据载货汽车的特点对其模型进行了简化,建立了十一自由度的多刚体系统动力学模型;以卡尔丹角描述载货汽车多刚体系统的姿态,运用多刚体系统动力学建模方法,建立了载货汽车十一自由度平顺性动力学模型及其动力学方程;激励分析中考...文章根据载货汽车的特点对其模型进行了简化,建立了十一自由度的多刚体系统动力学模型;以卡尔丹角描述载货汽车多刚体系统的姿态,运用多刚体系统动力学建模方法,建立了载货汽车十一自由度平顺性动力学模型及其动力学方程;激励分析中考虑了轮胎径向跳动的影响,采用逆快速傅里叶变换(inverse fast Fourier transform,IFFT)法建立了四轮相关路面随机输入时域模型;在此基础上,利用Matlab的GUI模块开发了载货汽车平顺性时域仿真系统,并以某型号载货汽车为例进行了平顺性时域仿真;最后,通过载货汽车平顺性实验,验证了该系统的仿真结果是准确可靠的。该系统实现了载货汽车多刚体系统的参数化建模与仿真,能有效地对载货汽车平顺性进行性能预测和评估。展开更多
This paper proposes to use Fast Fourier Transform （ FFT ） / Inverse Fast Fourier Transform （IFFT）, instead of vector-matrix multiplication, to implement the spreading/despreoding in Carrier-Interferometry Orthogon...This paper proposes to use Fast Fourier Transform （ FFT ） / Inverse Fast Fourier Transform （IFFT）, instead of vector-matrix multiplication, to implement the spreading/despreoding in Carrier-Interferometry Orthogonal Frequency Division Multiplexing （ CI/OFDM） and Pseudo-Orthogonal Carrier lnterferometry OFDM （PO-CI/OFDM）. That can improve the signal processing efficiency of CI/OFDM and PO-CI/OFDM systems by about 2N/log2N and 2N/（ 1 ＋ log2 N） times respectively and dose not make any difference to the system function and performance. Moreover, the effi- ciency benefits will increase with the increase of the number of sub-carriers. In addition to that, we point out that the transmitter of CI/OFDM is actually technically equivalent to that of a single-carrier system with cyclic-prefix and the receiver of CI/OFDM is a typical OFDM receiver with CI despreading. Hence the low Peak-to-Average Power Ratio （PA- PR） property and high anti-fading performance of CI/OFDM system can be well explained .展开更多
Traditional orthogonal frequency division multiplexing(OFDM) transmitter is implemented by exploiting inverse fast Fourier transform(IFFT), up-sampling, and low pass shaping filter(LPSF) modules, which occupy a large ...Traditional orthogonal frequency division multiplexing(OFDM) transmitter is implemented by exploiting inverse fast Fourier transform(IFFT), up-sampling, and low pass shaping filter(LPSF) modules, which occupy a large number of hardware resources and severely lower down the operation speed. To address these limitations, we propose a novel OFDM transmitter architecture, by which the aforementioned modules can be discarded and replaced with some simple switches. In the proposed architecture, direct digital synthesis(DDS) method is employed to generate digital sub-carriers and to transform OFDM data from frequency domain to time domain. Through some sophisticated simplifications, the proposed architecture can avoid using multipliers and remarkably save hardware resources. Finally, comparative experiments are carried out on field programmable gate array(FPGA) platform which demonstrates that our DDS-based architecture saves more than half of the hardware resources and doubles the achievable maximum frequency compared with traditional structure.展开更多
针对现阶段随机冰力时域模拟方法单一的问题,将一种经典的时域模拟方法——快速傅里叶逆变换(Inverse Fast Fourier Transform,IFFT)法,引入海上风机单桩基础随机冰载荷研究中。结合随机冰力模型,采用MATLAB软件平台编写冰载荷时域模拟...针对现阶段随机冰力时域模拟方法单一的问题,将一种经典的时域模拟方法——快速傅里叶逆变换(Inverse Fast Fourier Transform,IFFT)法,引入海上风机单桩基础随机冰载荷研究中。结合随机冰力模型,采用MATLAB软件平台编写冰载荷时域模拟程序。基于山东省东营市渤中某海上风电场8.5 MW单桩式风机的结构与尺寸,进行算例分析,考虑入射角度作用,得到随机冰力在单桩基础结构上的实际分布情况,对IFFT法模拟随机冰力的精度和速度进行综合评价。结果表明,IFFT法作为一种计算简单快速、结果精确的时域模拟方法,适用于单桩基础随机冰力的计算,且所编程序可实现输入少量参数,快速高效获得冰力数值与分布的目的,具有实用性和推广性。展开更多
文摘文章根据载货汽车的特点对其模型进行了简化,建立了十一自由度的多刚体系统动力学模型;以卡尔丹角描述载货汽车多刚体系统的姿态,运用多刚体系统动力学建模方法,建立了载货汽车十一自由度平顺性动力学模型及其动力学方程;激励分析中考虑了轮胎径向跳动的影响,采用逆快速傅里叶变换(inverse fast Fourier transform,IFFT)法建立了四轮相关路面随机输入时域模型;在此基础上,利用Matlab的GUI模块开发了载货汽车平顺性时域仿真系统,并以某型号载货汽车为例进行了平顺性时域仿真;最后,通过载货汽车平顺性实验,验证了该系统的仿真结果是准确可靠的。该系统实现了载货汽车多刚体系统的参数化建模与仿真,能有效地对载货汽车平顺性进行性能预测和评估。
基金Paper supported by the Teaching and Research Award Programfor Outstanding Young Professor in High Education Institute, MOE,P.R.C.
文摘This paper proposes to use Fast Fourier Transform （ FFT ） / Inverse Fast Fourier Transform （IFFT）, instead of vector-matrix multiplication, to implement the spreading/despreoding in Carrier-Interferometry Orthogonal Frequency Division Multiplexing （ CI/OFDM） and Pseudo-Orthogonal Carrier lnterferometry OFDM （PO-CI/OFDM）. That can improve the signal processing efficiency of CI/OFDM and PO-CI/OFDM systems by about 2N/log2N and 2N/（ 1 ＋ log2 N） times respectively and dose not make any difference to the system function and performance. Moreover, the effi- ciency benefits will increase with the increase of the number of sub-carriers. In addition to that, we point out that the transmitter of CI/OFDM is actually technically equivalent to that of a single-carrier system with cyclic-prefix and the receiver of CI/OFDM is a typical OFDM receiver with CI despreading. Hence the low Peak-to-Average Power Ratio （PA- PR） property and high anti-fading performance of CI/OFDM system can be well explained .
基金Supported by the Educational Science Research Project of Hubei Province(B2014243)
文摘Traditional orthogonal frequency division multiplexing(OFDM) transmitter is implemented by exploiting inverse fast Fourier transform(IFFT), up-sampling, and low pass shaping filter(LPSF) modules, which occupy a large number of hardware resources and severely lower down the operation speed. To address these limitations, we propose a novel OFDM transmitter architecture, by which the aforementioned modules can be discarded and replaced with some simple switches. In the proposed architecture, direct digital synthesis(DDS) method is employed to generate digital sub-carriers and to transform OFDM data from frequency domain to time domain. Through some sophisticated simplifications, the proposed architecture can avoid using multipliers and remarkably save hardware resources. Finally, comparative experiments are carried out on field programmable gate array(FPGA) platform which demonstrates that our DDS-based architecture saves more than half of the hardware resources and doubles the achievable maximum frequency compared with traditional structure.
文摘针对现阶段随机冰力时域模拟方法单一的问题,将一种经典的时域模拟方法——快速傅里叶逆变换(Inverse Fast Fourier Transform,IFFT)法,引入海上风机单桩基础随机冰载荷研究中。结合随机冰力模型,采用MATLAB软件平台编写冰载荷时域模拟程序。基于山东省东营市渤中某海上风电场8.5 MW单桩式风机的结构与尺寸,进行算例分析,考虑入射角度作用,得到随机冰力在单桩基础结构上的实际分布情况,对IFFT法模拟随机冰力的精度和速度进行综合评价。结果表明,IFFT法作为一种计算简单快速、结果精确的时域模拟方法,适用于单桩基础随机冰力的计算,且所编程序可实现输入少量参数,快速高效获得冰力数值与分布的目的,具有实用性和推广性。
