某商用车在开发阶段,路试发现乘客舱听到明显"嘶嘶声",初步判断是增压器的Hiss噪声向外辐射导致。对LMS Test Lab采集的车内噪声信号进行分析,确定此异响产生的原因是增压器Hiss噪声通过取气口辐射的。通过LMS Virtual Lab对...某商用车在开发阶段,路试发现乘客舱听到明显"嘶嘶声",初步判断是增压器的Hiss噪声向外辐射导致。对LMS Test Lab采集的车内噪声信号进行分析,确定此异响产生的原因是增压器Hiss噪声通过取气口辐射的。通过LMS Virtual Lab对消声器进行优化,调整原有宽频消声器的消声频率来优化进气系统,最终解决了Hiss噪声问题。展开更多
基于AAC比特流,提出了一种压缩域音频Hiss噪声抑制方法。该方法的输入为含噪音频的AAC比特流,输出为增强音频的AAC比特流。首先,利用修正的绝对中值标准差(MMAD,modified median absolute deviation)估计Hiss噪声,其次,利用修正的离散...基于AAC比特流,提出了一种压缩域音频Hiss噪声抑制方法。该方法的输入为含噪音频的AAC比特流,输出为增强音频的AAC比特流。首先,利用修正的绝对中值标准差(MMAD,modified median absolute deviation)估计Hiss噪声,其次,利用修正的离散傅里叶变换(MDFT,modified discrete Fourier transform)计算听觉掩蔽阈值参数,最后,根据参数软阈值方法得到增强的AAC比特流,并用于AAC解码器得到最终的增强音频信号。主观和客观测试结果表明,所提出的方法能有效去除AAC解码音频信号中的Hiss噪声,其性能明显优于现有的几种Hiss噪声消除方法。展开更多
Using wave measurements from the EMFISIS instrument onboard Van Allen Probes,we investigate statistically the spatial distributions of the intensity of plasmaspheric hiss waves.To reproduce these empirical results,we ...Using wave measurements from the EMFISIS instrument onboard Van Allen Probes,we investigate statistically the spatial distributions of the intensity of plasmaspheric hiss waves.To reproduce these empirical results,we establish a fitting model that is a thirdorder polynomial function of L-shell,magnetic local time(MLT),magnetic latitude(MLAT),and AE*.Quantitative comparisons indicate that the model’s fitting functions can reflect favorably the major empirical features of the global distribution of hiss wave intensity,including substorm dependence and the MLT asymmetry.Our results therefore provide a useful analytic model that can be readily employed in future simulations of global radiation belt electron dynamics under the impact of plasmaspheric hiss waves in geospace.展开更多
In this study, we analyze Cluster observations of whistler-mode chorus and hiss waves during the event of August 19-21, 2006. Chorus is present outside the plasmasphere and hiss occurs inside the plasmasphere. Using a...In this study, we analyze Cluster observations of whistler-mode chorus and hiss waves during the event of August 19-21, 2006. Chorus is present outside the plasmasphere and hiss occurs inside the plasmasphere. Using a recently constructed plasma boundary layer model, we perform a ray-tracing study on the propagation of chorus. Numerical results show that chorus can penetrate into the plasmasphere through the plasma boundary layer, evolving into hiss. The current data analysis and modeling provide a further observational support for the previous findings that chorus is the origin of plasmaspheric hiss.展开更多
"If I can't use normal channels,I'll [find her]some other was" Mr.Sun vowed to the camera,alarming millions of viewers who've followed the story of his obsession with a fellow shopper at a Beijin..."If I can't use normal channels,I'll [find her]some other was" Mr.Sun vowed to the camera,alarming millions of viewers who've followed the story of his obsession with a fellow shopper at a Beijing bookstore via a series of viral Pear Video cfips since mid-December.展开更多
文摘某商用车在开发阶段,路试发现乘客舱听到明显"嘶嘶声",初步判断是增压器的Hiss噪声向外辐射导致。对LMS Test Lab采集的车内噪声信号进行分析,确定此异响产生的原因是增压器Hiss噪声通过取气口辐射的。通过LMS Virtual Lab对消声器进行优化,调整原有宽频消声器的消声频率来优化进气系统,最终解决了Hiss噪声问题。
基金supported by the B-type Strategic Priority Program of the Chinese Academy of Sciences (Grant No. XDB41000000)the NSFC grants 41674163, 41974186, 41704162, 41904144, and 41904143+1 种基金the pre-research projects on Civil Aerospace Technologies No. D020308, D020104 and D020303funded by China National Space Administration。
文摘Using wave measurements from the EMFISIS instrument onboard Van Allen Probes,we investigate statistically the spatial distributions of the intensity of plasmaspheric hiss waves.To reproduce these empirical results,we establish a fitting model that is a thirdorder polynomial function of L-shell,magnetic local time(MLT),magnetic latitude(MLAT),and AE*.Quantitative comparisons indicate that the model’s fitting functions can reflect favorably the major empirical features of the global distribution of hiss wave intensity,including substorm dependence and the MLT asymmetry.Our results therefore provide a useful analytic model that can be readily employed in future simulations of global radiation belt electron dynamics under the impact of plasmaspheric hiss waves in geospace.
基金supported by National Natural Science Foundation of China(Nos.40925014,41274165,41204114)the Open Research Program from Key Laboratory of Basic Plasma Physics,Chinese Academy of Sciences(CAS)+1 种基金the Aid Program for Science and Technology Innovative Research Team in Higher Educational Institutions of Hunan Provincethe Construct Program of the Key Discipline in Hunan Province,China
文摘In this study, we analyze Cluster observations of whistler-mode chorus and hiss waves during the event of August 19-21, 2006. Chorus is present outside the plasmasphere and hiss occurs inside the plasmasphere. Using a recently constructed plasma boundary layer model, we perform a ray-tracing study on the propagation of chorus. Numerical results show that chorus can penetrate into the plasmasphere through the plasma boundary layer, evolving into hiss. The current data analysis and modeling provide a further observational support for the previous findings that chorus is the origin of plasmaspheric hiss.
文摘"If I can't use normal channels,I'll [find her]some other was" Mr.Sun vowed to the camera,alarming millions of viewers who've followed the story of his obsession with a fellow shopper at a Beijing bookstore via a series of viral Pear Video cfips since mid-December.
