准确测量管道介质声速有助于分析介质的密度和组分,而传统的声速测量方法重复性低、鲁棒性差。为了实现介质声速的准确测量,首先,基于管道一维声波理论推导出线阵列传感器在管道轴向位置的声信号模型,介绍了空气与水的理论声速计算公式...准确测量管道介质声速有助于分析介质的密度和组分,而传统的声速测量方法重复性低、鲁棒性差。为了实现介质声速的准确测量,首先,基于管道一维声波理论推导出线阵列传感器在管道轴向位置的声信号模型,介绍了空气与水的理论声速计算公式以及不同管材、管径和壁厚对声速衰减的影响;其次,采用MUSIC(multiple signal classification)波束形成算法将多通道时域数据转换至波数频率域,呈现出斜率与声速相关的“声学脊”;最后,使用DN50不锈钢管道分别在水和空气流量标准装置上进行声速测量实验,与理论数据相比,水中声速的相对误差为1.61%,重复性为0.45%,空气中声速的相对误差为0.59%,重复性为1.27%。结果表明MUSIC算法可准确测量管道一维声波的介质声速。展开更多
针对传统波达方向(Direction of Arrival,DOA)估计方法在低信噪比、少快拍数条件下表现性能差甚至失效的问题,提出了一种基于重构频域协方差矩阵的波达方位估计方法。该方法根据转化的频域信号进行共轭反向修正实现对噪声的抑制,构造出...针对传统波达方向(Direction of Arrival,DOA)估计方法在低信噪比、少快拍数条件下表现性能差甚至失效的问题,提出了一种基于重构频域协方差矩阵的波达方位估计方法。该方法根据转化的频域信号进行共轭反向修正实现对噪声的抑制,构造出了新的频域协方差矩阵,利用平均噪声子空间建立空间谱估计函数,通过谱峰搜索估计出信源的方位角。经仿真对比分析,所提改进方法可以识别多个相干信号,并且在低信噪比、少快拍数条件下仍然获得较好的方位估计性能,估计误差较传统算法降低2%~25%。展开更多
叶端定时是航空发动机叶片叶端振动非接触测量的有效手段,但其采样模式决定了所采信号具有高度欠采样特征,需要进行抗混叠频谱分析从而提取转子叶片固有频率这一关键指标。利用了前向平滑策略的改进多重信号分类法(multiple sIgnal clas...叶端定时是航空发动机叶片叶端振动非接触测量的有效手段,但其采样模式决定了所采信号具有高度欠采样特征,需要进行抗混叠频谱分析从而提取转子叶片固有频率这一关键指标。利用了前向平滑策略的改进多重信号分类法(multiple sIgnal classification,MUSIC)能实现抗混叠但无法充分发挥平滑方法的优势。因此,提出适用于叶端定时信号处理的前后向平滑MUSIC法,通过建立传感器的对称布局条件,利用前后向平滑方法代替前向平滑方法,得到更准确的自相关矩阵估计,进而提高叶片固有频率估计性能,并通过仿真和试验验证了在样本数量、算法参数等相同的情况下,前后向平滑MUSIC法的混叠与噪声抑制能力得到了提升。展开更多
针对空地信道动态测量对角度参数实时估计的低延迟需求,文章提出了一种基于无人机平台的空地信道测量系统的低延迟、高精度角度参数估计方法。该方法通过融合虚拟阵列缩减技术和快速特征值分解策略,可以降低传统多重信号分类(Multiple S...针对空地信道动态测量对角度参数实时估计的低延迟需求,文章提出了一种基于无人机平台的空地信道测量系统的低延迟、高精度角度参数估计方法。该方法通过融合虚拟阵列缩减技术和快速特征值分解策略,可以降低传统多重信号分类(Multiple Signal Classification,MUSIC)算法在协方差矩阵计算和特征值分解过程中的计算复杂度。外场实测数据表明,该方法在保持与经典算法相当精度时,可以大幅减少计算时间和延迟,适用于高动态空地测量场景的实时角度参数估计。展开更多
基于多信号分类算法(Multiple Signal Classification, MUSIC)算法的地下目标定位算法在多维遍历搜索过程中存在计算复杂度高、实时性差、无法应用于车载连续探测的问题。针对此问题,本文提出了一种基于多模态麻雀搜索的MUSIC地下目标...基于多信号分类算法(Multiple Signal Classification, MUSIC)算法的地下目标定位算法在多维遍历搜索过程中存在计算复杂度高、实时性差、无法应用于车载连续探测的问题。针对此问题,本文提出了一种基于多模态麻雀搜索的MUSIC地下目标快速定位算法,该算法推导了离地探测模型下的导向矢量模型,将MUSIC算法推广到地下管道定位中,并与寻优能力强、收敛速度快的麻雀搜索算法相结合,提高了算法的实时性。此外针对多目标场景下传统麻雀搜索算法无法同时搜索多个谱峰极值的问题,本文采用聚类算法对麻雀种群进行划分,从而形成多个子种群对目标峰值并行搜索,并结合粒子群算法实现峰值处局部搜索。仿真结果表明,本文所提方案在避免2D-MUSIC算法网格量化误差的同时,用时仅为2D-MUSIC算法的0.979%,且与同类算法相比具有更高的精度与搜索成功率。展开更多
With the development of new media technology and the popularity of the TikTok platform in China,a large number of popular vocal music teachers have flocked to online platforms for teaching.Online vocal music education...With the development of new media technology and the popularity of the TikTok platform in China,a large number of popular vocal music teachers have flocked to online platforms for teaching.Online vocal music education in China is undergoing a transformation and facing challenges.This study adopts an exploratory research approach,interviewing students learning pop vocal music,and observing popular pop teachers on TikTok.The advantages,disadvantages,techniques,and methods of domestic TikTok pop vocal music teaching were investigated and studied,and a series of experiences and suggestions for optimizing TikTok teaching were put forward.The results of this study are helpful for understanding the advantages and disadvantages of TikTok pop vocal music teaching and grasping the correct development direction.These guidance and suggestions can stimulate teachers’creativity and improve their vocal music teaching level.展开更多
实际变压器局部放电定位过程中放电源数目是未知的,常利用传统高分辨波达方向(direction of arrival,DOA)估计算法解决放电定位问题,但在信源数欠估计、过估计情况下存在定位精度低、误差大的问题。为此,本文提出了一种基于改进盖氏圆(g...实际变压器局部放电定位过程中放电源数目是未知的,常利用传统高分辨波达方向(direction of arrival,DOA)估计算法解决放电定位问题,但在信源数欠估计、过估计情况下存在定位精度低、误差大的问题。为此,本文提出了一种基于改进盖氏圆(geschgorin disk estimator,GDE)准则联合多重信号分类(multiple signal classification,MUSIC)算法的变压器局部放电多目标定位方法。首先,利用改进盖氏圆准则确定真实放电源数目;然后,在信源数确定的情况下利用MUSIC算法对多个局部放电源的波达方向进行估计。仿真结果表明,本方法定位精度高,且在白噪声和空间色噪声的情况下仍能对放电源的俯仰角和方位角进行准确估计,能够满足实际工程需求。展开更多
The article examines the diverse musical environments for older adults on the West Coast of North America,ranging from descriptions of regional variations in senior community living presented in a variety of sources,i...The article examines the diverse musical environments for older adults on the West Coast of North America,ranging from descriptions of regional variations in senior community living presented in a variety of sources,including fiction,and the place of music in institutional settings to various musical activities designed for older adults.Given that people living on the West Coast have diverse ethno-religious backgrounds,may or may not be sensitive to the music that surrounded them in their formative years at the local and national levels,and have different habits regarding listening to the radio or attending various musical events,additional aspects were taken into account,such as 1980s and 1990s music styles;ethnic musical heritage relevant to the West Coast population;classical,popular,and religious music on the radio;and affordable symphony orchestra programs.The article provides an overview that opens avenues for further exploration of its sub-topics.展开更多
文摘准确测量管道介质声速有助于分析介质的密度和组分,而传统的声速测量方法重复性低、鲁棒性差。为了实现介质声速的准确测量,首先,基于管道一维声波理论推导出线阵列传感器在管道轴向位置的声信号模型,介绍了空气与水的理论声速计算公式以及不同管材、管径和壁厚对声速衰减的影响;其次,采用MUSIC(multiple signal classification)波束形成算法将多通道时域数据转换至波数频率域,呈现出斜率与声速相关的“声学脊”;最后,使用DN50不锈钢管道分别在水和空气流量标准装置上进行声速测量实验,与理论数据相比,水中声速的相对误差为1.61%,重复性为0.45%,空气中声速的相对误差为0.59%,重复性为1.27%。结果表明MUSIC算法可准确测量管道一维声波的介质声速。
文摘针对传统波达方向(Direction of Arrival,DOA)估计方法在低信噪比、少快拍数条件下表现性能差甚至失效的问题,提出了一种基于重构频域协方差矩阵的波达方位估计方法。该方法根据转化的频域信号进行共轭反向修正实现对噪声的抑制,构造出了新的频域协方差矩阵,利用平均噪声子空间建立空间谱估计函数,通过谱峰搜索估计出信源的方位角。经仿真对比分析,所提改进方法可以识别多个相干信号,并且在低信噪比、少快拍数条件下仍然获得较好的方位估计性能,估计误差较传统算法降低2%~25%。
文摘叶端定时是航空发动机叶片叶端振动非接触测量的有效手段,但其采样模式决定了所采信号具有高度欠采样特征,需要进行抗混叠频谱分析从而提取转子叶片固有频率这一关键指标。利用了前向平滑策略的改进多重信号分类法(multiple sIgnal classification,MUSIC)能实现抗混叠但无法充分发挥平滑方法的优势。因此,提出适用于叶端定时信号处理的前后向平滑MUSIC法,通过建立传感器的对称布局条件,利用前后向平滑方法代替前向平滑方法,得到更准确的自相关矩阵估计,进而提高叶片固有频率估计性能,并通过仿真和试验验证了在样本数量、算法参数等相同的情况下,前后向平滑MUSIC法的混叠与噪声抑制能力得到了提升。
文摘针对空地信道动态测量对角度参数实时估计的低延迟需求,文章提出了一种基于无人机平台的空地信道测量系统的低延迟、高精度角度参数估计方法。该方法通过融合虚拟阵列缩减技术和快速特征值分解策略,可以降低传统多重信号分类(Multiple Signal Classification,MUSIC)算法在协方差矩阵计算和特征值分解过程中的计算复杂度。外场实测数据表明,该方法在保持与经典算法相当精度时,可以大幅减少计算时间和延迟,适用于高动态空地测量场景的实时角度参数估计。
文摘基于多信号分类算法(Multiple Signal Classification, MUSIC)算法的地下目标定位算法在多维遍历搜索过程中存在计算复杂度高、实时性差、无法应用于车载连续探测的问题。针对此问题,本文提出了一种基于多模态麻雀搜索的MUSIC地下目标快速定位算法,该算法推导了离地探测模型下的导向矢量模型,将MUSIC算法推广到地下管道定位中,并与寻优能力强、收敛速度快的麻雀搜索算法相结合,提高了算法的实时性。此外针对多目标场景下传统麻雀搜索算法无法同时搜索多个谱峰极值的问题,本文采用聚类算法对麻雀种群进行划分,从而形成多个子种群对目标峰值并行搜索,并结合粒子群算法实现峰值处局部搜索。仿真结果表明,本文所提方案在避免2D-MUSIC算法网格量化误差的同时,用时仅为2D-MUSIC算法的0.979%,且与同类算法相比具有更高的精度与搜索成功率。
文摘With the development of new media technology and the popularity of the TikTok platform in China,a large number of popular vocal music teachers have flocked to online platforms for teaching.Online vocal music education in China is undergoing a transformation and facing challenges.This study adopts an exploratory research approach,interviewing students learning pop vocal music,and observing popular pop teachers on TikTok.The advantages,disadvantages,techniques,and methods of domestic TikTok pop vocal music teaching were investigated and studied,and a series of experiences and suggestions for optimizing TikTok teaching were put forward.The results of this study are helpful for understanding the advantages and disadvantages of TikTok pop vocal music teaching and grasping the correct development direction.These guidance and suggestions can stimulate teachers’creativity and improve their vocal music teaching level.
文摘实际变压器局部放电定位过程中放电源数目是未知的,常利用传统高分辨波达方向(direction of arrival,DOA)估计算法解决放电定位问题,但在信源数欠估计、过估计情况下存在定位精度低、误差大的问题。为此,本文提出了一种基于改进盖氏圆(geschgorin disk estimator,GDE)准则联合多重信号分类(multiple signal classification,MUSIC)算法的变压器局部放电多目标定位方法。首先,利用改进盖氏圆准则确定真实放电源数目;然后,在信源数确定的情况下利用MUSIC算法对多个局部放电源的波达方向进行估计。仿真结果表明,本方法定位精度高,且在白噪声和空间色噪声的情况下仍能对放电源的俯仰角和方位角进行准确估计,能够满足实际工程需求。
文摘The article examines the diverse musical environments for older adults on the West Coast of North America,ranging from descriptions of regional variations in senior community living presented in a variety of sources,including fiction,and the place of music in institutional settings to various musical activities designed for older adults.Given that people living on the West Coast have diverse ethno-religious backgrounds,may or may not be sensitive to the music that surrounded them in their formative years at the local and national levels,and have different habits regarding listening to the radio or attending various musical events,additional aspects were taken into account,such as 1980s and 1990s music styles;ethnic musical heritage relevant to the West Coast population;classical,popular,and religious music on the radio;and affordable symphony orchestra programs.The article provides an overview that opens avenues for further exploration of its sub-topics.
