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Journal articles on the topic 'Rotational echoes'

Author: Grafiati

Published: 7 July 2024

Last updated: 31 July 2025

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1

van der Struijf, C., T. Ph Pelupessy, E. E. van Faassen, and Y. K. Levine. "Rotational Motion of Ca-ATPase Monitored by Electron Spin Echoes." Journal of Magnetic Resonance, Series B 111, no. 2 (1996): 158–67. http://dx.doi.org/10.1006/jmrb.1996.0074.

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2

Karlsson, Torgny, Michael Helmle, N. D. Kurur, and Malcolm H. Levitt. "Rotational resonance echoes in the nuclear magnetic resonance of spinning solids." Chemical Physics Letters 247, no. 4-6 (1995): 534–40. http://dx.doi.org/10.1016/s0009-2614(95)01257-5.

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3

Rosenberg, Dina, Ran Damari, Shimshon Kallush, and Sharly Fleischer. "Rotational Echoes: Rephasing of Centrifugal Distortion in Laser-Induced Molecular Alignment." Journal of Physical Chemistry Letters 8, no. 20 (2017): 5128–35. http://dx.doi.org/10.1021/acs.jpclett.7b02215.

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4

Lu, Jian, Yaqing Zhang, Harold Y. Hwang, Benjamin K. Ofori-Okai, Sharly Fleischer, and Keith A. Nelson. "Nonlinear two-dimensional terahertz photon echo and rotational spectroscopy in the gas phase." Proceedings of the National Academy of Sciences 113, no. 42 (2016): 11800–11805. http://dx.doi.org/10.1073/pnas.1609558113.

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Ultrafast 2D spectroscopy uses correlated multiple light−matter interactions for retrieving dynamic features that may otherwise be hidden under the linear spectrum; its extension to the terahertz regime of the electromagnetic spectrum, where a rich variety of material degrees of freedom reside, remains an experimental challenge. We report a demonstration of ultrafast 2D terahertz spectroscopy of gas-phase molecular rotors at room temperature. Using time-delayed terahertz pulse pairs, we observe photon echoes and other nonlinear signals resulting from molecular dipole orientation induced by mul

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5

SHARMA, BL. "Hailstorms near Nagpur -A radar study." MAUSAM 18, no. 2 (2022): 255–66. http://dx.doi.org/10.54302/mausam.v18i2.4446.

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In the present study, which has been made by a Decca type 41 radar, it has been shown that the hailstorms over Kamptee situated at a distance of 10 n, miles towards northeast of the radar station had occurred due to the presence of a rotational echo with characteristic hook features, An attempt has been made to find out (a) the speed and direction of the movement of the rotational and non-rotational echoes and their collision courses in directional convergence, (b) to calculate the terminal velocity of the precipitation particles and the corresponding particle size from the streamers, associat

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6

Watanabe, Jun-Ichi. "RADAR Observations of Leonids in Japan." Highlights of Astronomy 11, no. 2 (1998): 1020. http://dx.doi.org/10.1017/s153929960001950x.

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We are observing meteor showers using the MU radar located at Shigaraki, Japan. This is a Mesosphere, Stratosphere and Troposphere radar, belonging to the Kyoto University, with a frequency and a peak power of 46.5M.ffz and 1MW, respectively. This system is characterized by the versatility of the antenna array. By using four antennas out of 475 Yagi arrays together with four receiver channels, we can observe more than several hundred meteor echoes per hour. The beam applied at the meteor observation is a static “doughnut beam”, which is the rotational symmetrical pattern to the vertical line.

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7

Zhou, Zibo, Libing Jiang, and Zhuang Wang. "A novel image registration method for InISAR 3D imaging." MATEC Web of Conferences 232 (2018): 02044. http://dx.doi.org/10.1051/matecconf/201823202044.

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Image registration is a key intermediate step for Interferometric Inverse Synthetic Aperture Radar (InISAR) three-dimensional (3D) imaging. It arranges the same scatterers of the target on the same pixel cell in different ISAR images, which makes the interferometric processing carried on between the same scatterers to obtain its 3D coordinates. This paper proposes a novel ISAR image registration method of three steps. Firstly, chirp Fourier transform is used to estimate the rotational angular velocity of the target. Secondly, the compensation phase is constructed, according to the rotational a

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8

Karlsson, Torgny, and Malcolm H. Levitt. "Longitudinal rotational resonance echoes in solid state nuclear magnetic resonance: Investigation of zero quantum spin dynamics." Journal of Chemical Physics 109, no. 13 (1998): 5493–507. http://dx.doi.org/10.1063/1.477168.

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9

Bertmer, Marko, and Hellmut Eckert. "Dephasing of spin echoes by multiple heteronuclear dipolar interactions in rotational echo double resonance NMR experiments." Solid State Nuclear Magnetic Resonance 15, no. 3 (1999): 139–52. http://dx.doi.org/10.1016/s0926-2040(99)00050-8.

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10

Di Girolamo, Paolo, Noemi Franco, Marco Di Paolantonio, Donato Summa, and Davide Dionisi. "Atmospheric Thermodynamic Profiling through the Use of a Micro-Pulse Raman Lidar System: Introducing the Compact Raman Lidar MARCO." Sensors 23, no. 19 (2023): 8262. http://dx.doi.org/10.3390/s23198262.

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It was for a long time believed that lidar systems based on the use of high-repetition micro-pulse lasers could be effectively used to only stimulate atmospheric elastic backscatter echoes, and thus were only exploited in elastic backscatter lidar systems. Their application to stimulate rotational and roto-vibrational Raman echoes, and consequently, their exploitation in atmospheric thermodynamic profiling, was considered not feasible based on the technical specifications possessed by these laser sources until a few years ago. However, recent technological advances in the design and developmen

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11

Bu, Xiangxi, Zhuo Zhang, Xingdong Liang, et al. "A Novel Scheme for MIMO-SAR Systems Using Rotational Orbital Angular Momentum." Sensors 18, no. 10 (2018): 3511. http://dx.doi.org/10.3390/s18103511.

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The vortex electromagnetic (EM) wave with orbital angular momentum (OAM) brings a new degree of freedom for synthetic aperture radar (SAR) imaging, although to date, its application to multi-input multi-output (MIMO) SAR has not yet been widely reported. In this paper, an orbital angular momentum (OAM)-based MIMO-SAR system is proposed. The rotational Doppler Effect (RDE) of vortex EM waves offers a novel scheme for an OAM-based MIMO-SAR system. By transmitting the rotational vortex EM waves, echoes of different OAM modes can be discriminated by a bandpass filter in the range-Doppler domain. T

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12

Sud, Seema. "Noise and Interference Suppression in Sonar Echoes Using the Fractional Fourier Transform." European Journal of Engineering Research and Science 2, no. 7 (2017): 40. http://dx.doi.org/10.24018/ejers.2017.2.7.422.

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The Fractional Fourier Transform (FrFT) enables separation of signals from noise and interference by utilizing the entire time-frequency space. Signals are filtered by rotating to a new time axis ‘ta’, with rotational parameter ‘a’, selected using some metric such as mean-square error (MSE) between a desired signal-of-interest (SOI) and its estimate. The FrFT has been applied to numerous problems, but it is most suited for applications such as sonar and radar, when the time-frequency distribution of the SOI and the undesired environment are different. It can greatly outperform the conventional

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13

Sud, Seema. "Noise and Interference Suppression in Sonar Echoes Using the Fractional Fourier Transform." European Journal of Engineering and Technology Research 2, no. 7 (2017): 40–44. http://dx.doi.org/10.24018/ejeng.2017.2.7.422.

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The Fractional Fourier Transform (FrFT) enables separation of signals from noise and interference by utilizing the entire time-frequency space. Signals are filtered by rotating to a new time axis ‘ta’, with rotational parameter ‘a’, selected using some metric such as mean-square error (MSE) between a desired signal-of-interest (SOI) and its estimate. The FrFT has been applied to numerous problems, but it is most suited for applications such as sonar and radar, when the time-frequency distribution of the SOI and the undesired environment are different. It can greatly outperform the conventional

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14

Wang, Jiakun, Min Zhang, Pengbo Wei, and Panpan Jiang. "ISAR imaging of moving satellite based on GO–PO scattering model." International Journal of Microwave and Wireless Technologies 9, no. 7 (2017): 1499–507. http://dx.doi.org/10.1017/s1759078717000083.

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An efficient algorithm is proposed for the radar cross-section (RCS) prediction of complex target with electronically large size, which is a combination of geometrical optics and physical optics (GO–PO) method. The method taking the multiple reflections into account is applied to the electromagnetic scattering analysis of a satellite model. Then RCS curves of entire satellite model and the model without antenna structure are figured out. Based on the simulated echoes, the traditional inverse synthetic aperture radar (ISAR) images are discussed. Moreover, an application of motion compensation t

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15

Chung, Kao-Shen, and I.-An Yao. "Improving Radar Echo Lagrangian Extrapolation Nowcasting by Blending Numerical Model Wind Information: Statistical Performance of 16 Typhoon Cases." Monthly Weather Review 148, no. 3 (2020): 1099–120. http://dx.doi.org/10.1175/mwr-d-19-0193.1.

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Abstract Severe weather nowcasting is a crucial mission of atmospheric science for the betterment of society to save life, limb, and property. In this study, composite radar data from the Central Weather Bureau of 16 typhoons are collected to examine the statistical performance of the McGill Algorithm for Precipitation nowcasting using Lagrangian Extrapolation (MAPLE) over Taiwan, an extrapolation algorithm that predicts future precipitation based on current radar echoes. In addition, instead of mixing the precipitation between radar extrapolation and numerical model forecast as in previous st

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16

Gullion, Terry, and Shimon Vega. "A simple magic angle spinning NMR experiment for the dephasing of rotational echoes of dipolar coupled homonuclear spin pairs." Chemical Physics Letters 194, no. 4-6 (1992): 423–28. http://dx.doi.org/10.1016/0009-2614(92)86076-t.

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17

Benzeroual, Hajar, Abdellatif Khamlichi, and Alia Zakriti. "Detection of Transverse Defects in Rails Using Noncontact Laser Ultrasound." Proceedings 42, no. 1 (2019): 43. http://dx.doi.org/10.3390/ecsa-6-06556.

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Rail inspections are required and used to ensure safety and preserve the availability of railway infrastructure. According to the statistics published by railroad administrations worldwide, the transverse fissure appearing in railhead is the principal cause of rail accidents. These particular defects are initiated inside the railhead. Detection of these cracks has always been challenging because a defect signature remains mostly small until the defect size reaches a significant value. The present work deals with the theoretical analysis of an integrated contact-less system for rail diagnosis,

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18

Benzeroual, Hajar, Abdellatif Khamlichi, and Alia Zakriti. "Reliability of rail transverse flaw detection by means of an embedded ultrasonic based device." MATEC Web of Conferences 191 (2018): 00005. http://dx.doi.org/10.1051/matecconf/201819100005.

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The main causes of train derailment are related to rail defects such as head surface defects, horizontal defects, vertical longitudinal split defects, star cracks at colt holes and diagonal crack in web. The most adverse form of these defects consists of transverse flaws that are either opened or internal. These flaws are developed generally in a plane which is orthogonal to the rail direction. Detection of these defects is essential in order to improve security of rail roads and to prevent catastrophic failures. Most of the inspection techniques of rails relay on eddy currents, electromagneti

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19

Chen, Pinhui, Brice J. Albert, Chukun Gao, et al. "Magic angle spinning spheres." Science Advances 4, no. 9 (2018): eaau1540. http://dx.doi.org/10.1126/sciadv.aau1540.

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Magic angle spinning (MAS) is commonly used in nuclear magnetic resonance of solids to improve spectral resolution. Rather than using cylindrical rotors for MAS, we demonstrate that spherical rotors can be spun stably at the magic angle. Spherical rotors conserve valuable space in the probe head and simplify sample exchange and microwave coupling for dynamic nuclear polarization. In this current implementation of spherical rotors, a single gas stream provides bearing gas to reduce friction, drive propulsion to generate and maintain angular momentum, and variable temperature control for thermos

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20

Brown, Rodger A., Bradley A. Flickinger, Eddie Forren, et al. "Improved Detection of Severe Storms Using Experimental Fine-Resolution WSR-88D Measurements." Weather and Forecasting 20, no. 1 (2005): 3–14. http://dx.doi.org/10.1175/waf-832.1.

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Abstract Doppler velocity and reflectivity measurements from Weather Surveillance Radar-1988 Doppler (WSR-88D) radars provide important input to forecasters as they prepare to issue short-term severe storm and tornado warnings. Current-resolution data collected by the radars have an azimuthal spacing of 1.0° and range spacing of 1.0 km for reflectivity and 0.25 km for Doppler velocity and spectrum width. To test the feasibility of improving data resolution, National Severe Storms Laboratory’s test bed WSR-88D (KOUN) collected data in severe thunderstorms using 0.5°-azimuthal spacing and 0.25-k

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21

Gong, Rui, Ling Wang, Bin Wu, Gong Zhang, and Daiyin Zhu. "Optimal Space-Borne ISAR Imaging of Space Objects with Co-Maximization of Doppler Spread and Spacecraft Component Area." Remote Sensing 16, no. 6 (2024): 1037. http://dx.doi.org/10.3390/rs16061037.

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The Inverse Synthetic Aperture Radar (ISAR) has been proven to be an effective tool for space target sensing due to its capability of performing high-resolution imaging. Since the component information of the spacecraft is key to the identification of the target and diagnosis of its status, ISAR images with a clear and complete representation of the typical components are much desired. This requires a selection of the imaging time, during which a certain spacecraft component has a good projection on the ISAR image plane with the shape feature well conserved and a high resolution. In addition,

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22

Ma, Xiangchao, Junmin Meng, Chenqing Fan, and Ping Chen. "Effects of Wave-Induced Doppler Velocity on the Sea Surface Current Measurements by Ka-Band Real-Aperture Radar with Small Incidence Angle." Remote Sensing 15, no. 4 (2023): 1127. http://dx.doi.org/10.3390/rs15041127.

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The Doppler shift of microwave radar sea surface echoes serves as the foundation for sea surface current field retrieval; it includes the shift caused by satellite platform motion, ocean waves, and sea surface currents. The Doppler shift caused by ocean waves is known as the wave-induced Doppler velocity (UWD), and its removal is critical for the accurate retrieval of sea surface current fields. The low-incidence Ka-band real-aperture radar rotary scan regime has the capability of directly observing wide-swath two-dimensional current fields, but as a new regime to be further explored and valid

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23

Yi, Xianzhou. "Three DOF Rotation Compensation in Floating HFSWR for Ocean Current Inversion." Journal of Physics: Conference Series 2718, no. 1 (2024): 012017. http://dx.doi.org/10.1088/1742-6596/2718/1/012017.

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Abstract High-frequency surface wave radar (HFSWR) has been widely used for ocean surface current inversion. Floating this radar can realize the ocean surface inversion among large areas far away from the coastline. However, six degree-of-freedom (DOF) movements will set the barrier for the ocean current inversion on its radial velocity estimation and direction of arrival estimation. Among these movements, three DOF rotations can cause both Doppler modulation and azimuth modulation while three DOF translations only cause Doppler modulation which is dependent on the arrival direction of echoes.

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24

SHARIFF, KARIM, and ALAN WRAY. "Analysis of the radar reflectivity of aircraft vortex wakes." Journal of Fluid Mechanics 463 (July 25, 2002): 121–61. http://dx.doi.org/10.1017/s0022112002008674.

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Radar has been proposed as a way of tracking wake vortices to reduce aircraft spacing and tests have revealed radar echoes from aircraft wakes in clear air. The mechanism causing refractive index gradients in these tests is thought to be the same as that for homogeneous and isotropic atmospheric turbulence in the Kolmogorov inertial range, for which there is a scattering analysis due to Tatarski. In reality, however, the structure of aircraft wakes has a significant coherent part superimposed with turbulence, about whose structure very little is known. This work adopts a picture of a coherent

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25

Sergeev, N. A. "Influence of Molecular Hindered Rotations on NQR Spin Echoes." Zeitschrift für Physikalische Chemie 219, no. 8 (2005): 1107–19. http://dx.doi.org/10.1524/zpch.2005.219.8.1107.

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26

Wang, Cheng, Wulong Guo, Haisheng Zhao, Liang Chen, Yiwen Wei, and Yuanyuan Zhang. "Improving the Topside Profile of Ionosonde with TEC Retrieved from Spaceborne Polarimetric SAR." Sensors 19, no. 3 (2019): 516. http://dx.doi.org/10.3390/s19030516.

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Signals from spaceborne polarimetric synthetic aperture radar will suffer from Faraday rotations when they propagate through the ionosphere, especially those at L-band or lower frequencies, such as signals from the Phased Array type L-band Synthetic Aperture Radar (PALSAR). For this reason, Faraday rotation compensation should be considered. On the other hand, Faraday rotation could also be retrieved from distorted echoes. Moreover, combining Faraday rotation with the radar parameters and the model of magnetic field, we could derive the total electron content (TEC) along the signal path. Benef

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27

Yang, Shenghui, Shiqiang Li, Xiaoxue Jia, Yonghua Cai, and Yifei Liu. "An Efficient Translational Motion Compensation Approach for ISAR Imaging of Rapidly Spinning Targets." Remote Sensing 14, no. 9 (2022): 2208. http://dx.doi.org/10.3390/rs14092208.

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For inverse synthetic aperture radar (ISAR) imaging of rapidly spinning targets, the large migration through range cells (MTRC) results in weak coherence between adjacent echoes, which makes the conventional envelope alignment method unable to be applied. By analyzing the correlation between the echoes, a translational motion compensation (TMC) method for rapidly spinning targets is proposed. Firstly, the rotation period of the target is estimated by the incoherent accumulation method for the echo signal after range compression. Secondly, Kalman filtering is performed on the shift values requi

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28

Su, Aifang, Han Li, Liman Cui, and Yungang Chen. "A Convection Nowcasting Method Based on Machine Learning." Advances in Meteorology 2020 (January 27, 2020): 1–13. http://dx.doi.org/10.1155/2020/5124274.

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In this study, a convection nowcasting method based on machine learning was proposed. First, the historical data were back-calculated using the pyramid optical flow method. Next, the generated optical flow field information of each pixel and the Red-Green-Blue (RGB) image information were input into the Convolutional Long Short-Term Memory (ConvLSTM) algorithm for training purposes. During the extrapolation process, dynamic characteristics such as the rotation, convergence, and divergence in the optical flow field were also used as predictors to form an optimal nowcasting model. The test analy

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29

Liang, Mengning, Ross Harder, and Ian K. Robinson. "Brownian motion studies of viscoelastic colloidal gels by rotational single particle tracking." IUCrJ 1, no. 3 (2014): 172–78. http://dx.doi.org/10.1107/s2052252514006022.

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Colloidal gels have unique properties due to a complex microstructure which forms into an extended network. Although the bulk properties of colloidal gels have been studied, there has been difficulty correlating those properties with individual colloidal dynamics on the microscale due to the very high viscosity and elasticity of the material. We utilize rotational X-ray tracking (RXT) to investigate the rotational motion of component crystalline colloidal particles in a colloidal gel of alumina and decanoic acid. Our investigation has determined that the high elasticity of the bulk is echoed b

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30

Uspensky, M., P. Eglitis, H. Opgenoorth, G. Starkov, T. Pulkkinen, and R. Pellinen. "On auroral dynamics observed by HF radar: 1. Equatorward edge of the afternoon-evening diffuse luminosity belt." Annales Geophysicae 18, no. 12 (2000): 1560–75. http://dx.doi.org/10.1007/s00585-001-1560-x.

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Abstract. Observations and modelling are presented which illustrate the ability of the Finland CUTLASS HF radar to monitor the afternoon-evening equatorward auroral boundary during weak geomagnetic activity. The subsequent substorm growth phase development was also observed in the late evening sector as a natural continuation of the preceding auroral oval dynamics. Over an 8 h period the CUTLASS Finland radar observed a narrow (in range) and persistent region of auroral F- and (later) E-layer echoes which gradually moved equatorward, consistent with the auroral oval diurnal rotation. This echo

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31

Zhang, Lingling, Yongzhong Zhu, Yijun Chen, Wenxuan Xie, and Hang Yuan. "Parameter Extraction of Accelerated Moving Targets under Non-Quasi-Axial Incidence Conditions Based on Vortex Electromagnetic Wave Radar." Remote Sensing 16, no. 11 (2024): 1931. http://dx.doi.org/10.3390/rs16111931.

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Vortex electromagnetic wave radar carrying orbital angular momentum can compensate for the deficiency of planar electromagnetic wave radar in detecting motion parameters perpendicular to the direction of electromagnetic wave propagation, thus providing more information for target recognition, which has become a hot research field in recent years. However, existing research makes it difficult to obtain the acceleration and rotation centers of targets under non-quasi-axial incidence conditions of vortex electromagnetic waves. Based on this, this article proposes a variable speed motion target pa

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32

Liebmann, Max, Alexander Treffer, Martin Bock, et al. "Self-imaging of tailored vortex pulse arrays and spectral Gouy rotation echoes." Optics Letters 44, no. 4 (2019): 1047. http://dx.doi.org/10.1364/ol.44.001047.

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33

He, Zhang, Yi, Jin, and Dong. "Suppressing Paired Echoes Caused by Stair-Step Antenna Steering in TOPS SAR Imaging." Remote Sensing 11, no. 21 (2019): 2544. http://dx.doi.org/10.3390/rs11212544.

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The use of electronically steered antennas in the azimuth dimension typically leads to a staircase-like antenna beam steering law in the Terrain Observation by Progressive Scan (TOPS) wide-swath synthetic aperture radar (SAR) data acquisition mode, which will introduce paired echoes in the focused images. This paper proposes a new approach for removing such paired echoes from TOPS SAR images based on the generalization of the ideal optimum filtering concept, which can be implemented easily in the SAR data processing. Modeling the amplitude-modulated azimuth signal shows that the absolute phase

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34

Bell, Michael M., Wen-Chau Lee, Cory A. Wolff, and Huaqing Cai. "A Solo-Based Automated Quality Control Algorithm for Airborne Tail Doppler Radar Data." Journal of Applied Meteorology and Climatology 52, no. 11 (2013): 2509–28. http://dx.doi.org/10.1175/jamc-d-12-0283.1.

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AbstractAn automated quality control preprocessing algorithm for removing nonweather radar echoes in airborne Doppler radar data has been developed. This algorithm can significantly reduce the time and experience level required for interactive radar data editing prior to dual-Doppler wind synthesis or data assimilation. The algorithm uses the editing functions in the Solo software package developed by the National Center for Atmospheric Research to remove noise, Earth-surface, sidelobe, second-trip, and other artifacts. The characteristics of these nonweather radar returns, the algorithm to id

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35

Sheng, L. Q., J. H. Pei, and X. Y. Liu. "Self-affine Fractal Modelling of Aircraft Echoes from Low-resolution Radars." Defence Science Journal 66, no. 2 (2016): 151. http://dx.doi.org/10.14429/dsj.66.8423.

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<p>For complex targets, the non rigid vibration of an aircraft as well as its attitude changes and the rotation of its rotating parts will induce complex nonlinear modulation on its echo from low-resolution radars. If one performs the fractal analysis of measures on an aircraft echo, it may offer a fine description of the dynamic characteristics which induce the echo structure. On basis of introducing self-affine fractal theory, the paper models real recorded aircraft echo data from a low-resolution radar using the self-affine fractal representation, and investigates the application of e

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36

Shi, Zheng, Chen Gang, Li Shuanlao, et al. "Detection Method for Asteroid Interior Structure Verified by Scale Model." Journal of Physics: Conference Series 2887, no. 1 (2024): 012015. http://dx.doi.org/10.1088/1742-6596/2887/1/012015.

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Abstract We have developed a radar scheme for detecting the asteroid interior structure. Using the auto rotation of an asteroid, radar system can hover at a fix distance from the asteroid, and continuously measure the internal structure echoes at different spin angles, which can be processed to obtain the internal structure profile image. Through simulation and scale model test, we have verified the internal structure imaging results and conformed the effectiveness of the hovering radar method. The proposed radar scheme was selected as the science payload for internal structure in China’s aste

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37

Chen, Xiaodong, Ming Li, Yan Li, Yi Wang, and Daoyin Yu. "Synthetic aperture focusing for medical endoscopic ultrasonography." Journal of X-Ray Science and Technology: Clinical Applications of Diagnosis and Therapeutics 19, no. 1 (2011): 127–37. http://dx.doi.org/10.3233/xst-2010-028200282.

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A new approach for synthetic aperture focusing (SAF) to enhance both signal to noise ratio (SNR) and resolution in endoscopic ultrasonography is presented in this paper. The technique uses the rotation feature of single element transducer probe, and transmits and receives the echoes at different time and locations during the rotary scanning. Based on theoretical simulation, axial and lateral matched-filters are developed according to the coded and linear frequency modulated characteristics of the echoes to implement axial and lateral compression. The effects of SNR and resolution enhancements

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38

Dittmer, Jens, and Geoffrey Bodenhausen. "Quenching Echo Modulations in NMR Spectroscopy." ChemPhysChem 7, no. 4 (2006): 831–36. https://doi.org/10.1002/cphc.200500403.

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In NMR spectroscopy, homonuclear scalar couplings normally lead to modulations of spin echoes that tend to interfere with the accurate determination of transverse relaxation rates by Carr–Purcell–Meiboom–Gill (CPMG) multiple refocusing experiments. Surprisingly, the echo modulations are largely cancelled when the refocusing pulses applied to the coupling partner deviate slightly from ideal π rotations due to tilted effective radio-frequency (RF) fields, even at offsets that are much smaller than the radio-frequency amplitude. Experiments and simulations illustrate these effects for two-spin IS

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Costa, Andreu F., Daniel W. Petrie, Yi-Fen Yen, and Maria Drangova. "Using the axis of rotation of polar navigator echoes to rapidly measure 3D rigid-body motion." Magnetic Resonance in Medicine 53, no. 1 (2004): 150–58. http://dx.doi.org/10.1002/mrm.20306.

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40

Ghasemi Azar, A., H. Rezaei, and H. Moradpour. "Some applications of the Shapiro time delay." Serbian Astronomical Journal, no. 207 (2023): 1–7. http://dx.doi.org/10.2298/saj2307001g.

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Listening to echoes has long been a way to estimate distances, a technique whose backbone is the time delay. The gravitational field also creates a time delay, called Shapiro time delay, that helps us extract some information from the field and is indeed due to the photon journey through the field. Here, the ability of the Shapiro effect to distinguish naked singularities from non-naked ones (black holes) is discussed. It is also inferred that this time delay may be hired to compare the various types of singularities with different dimensions. Besides them, the possibility of detecting the rot

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Hysell, D. L., J. Drexler, E. B. Shume, et al. "Combined radar observations of equatorial electrojet irregularities at Jicamarca." Annales Geophysicae 25, no. 2 (2007): 457–73. http://dx.doi.org/10.5194/angeo-25-457-2007.

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Abstract. Daytime equatorial electrojet plasma irregularities were investigated using five distinct radar diagnostics at Jicamarca including range-time-intensity (RTI) mapping, Faraday rotation, radar imaging, oblique scattering, and multiple-frequency scattering using the new AMISR prototype UHF radar. Data suggest the existence of plasma density striations separated by 3–5 km and propagating slowly downward. The striations may be caused by neutral atmospheric turbulence, and a possible scenario for their formation is discussed. The Doppler shifts of type 1 echoes observed at VHF and UHF freq

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Lee, Yasuharu, Naoki Mori, Daisuke Nakamura, et al. "New Approach for Rotational Dyssynchrony Using Three-Dimensional Speckle Tracking Echocardiography." Echocardiography 31, no. 4 (2013): 492–98. http://dx.doi.org/10.1111/echo.12406.

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Doeleman, S. S., C. J. Lonsdale, and L. J. Greenhill. "86 GHz VLBI Imaging of the SiO Masers in VX Sgr." International Astronomical Union Colloquium 164 (1998): 363–64. http://dx.doi.org/10.1017/s0252921100045942.

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AbstractWe present the first 86 GHz spectral line VLBI map. Strong SiO masers in the late type star VX Sgr are mapped with a relative astrometry of 0.15 mas revealing an irregular ring of maser emission that echos structure seen at 43 GHz. A surprising feature of this map is the detection of a large (0.5 km s−1 AU−1 ) linear velocity gradient that can be interpreted as rigid rotation of the circumstellar envelope.

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Kroh, Patrick K., Ralph Simon, and Stefan J. Rupitsch. "Classification of Sonar Targets in Air—A Neural Network Approach." Proceedings 2, no. 13 (2018): 929. http://dx.doi.org/10.3390/proceedings2130929.

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Ultrasonic sonar sensors are commonly used for contactless distance measurements in application areas such as automotive and mobile robotics. They can also be used to identify and classify sound reflecting objects. In the presented work, we classify simple sonar targets of different geometric shape and size. For this purpose, we built a test stand for echo measurements that facilitates defined arbitrary translation and rotation of the targets. Artificial neural networks (ANNs) with multiple hidden layers were used as classifiers and different features were evaluated. The focus was on two featu

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Elford, W. G., and A. D. Taylor. "Measurement of Faraday rotation of radar meteor echoes for the modelling of electron densities in the lower ionosphere." Journal of Atmospheric and Solar-Terrestrial Physics 59, no. 9 (1997): 1021–24. http://dx.doi.org/10.1016/s1364-6826(96)00083-1.

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Alizadehasl, Azin, Anita Sadeghpour, Reza Hali, Hooman Bakhshandeh Abkenar, and Luigi Badano. "Assessment of left and right ventricular rotational interdependence: A speckle tracking echocardiographic study." Echocardiography 34, no. 3 (2017): 415–21. http://dx.doi.org/10.1111/echo.13452.

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Rebull, L. M., J. R. Stauffer, L. A. Hillenbrand, A. M. Cody, Ethan Kruse, and Brian P. Powell. "Rotation of Low-mass Stars in Upper Centaurus–Lupus and Lower Centaurus–Crux with TESS." Astronomical Journal 164, no. 3 (2022): 80. http://dx.doi.org/10.3847/1538-3881/ac75f1.

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Abstract We present stellar rotation rates derived from Transiting Exoplanet Survey Satellite (TESS) light curves for stars in Upper Centaurus–Lupus (UCL; ∼136 pc, ∼16 Myr) and Lower Centaurus–Crux (LCC; ∼115 pc, ∼17 Myr). We find spot-modulated periods (P) for ∼90% of members. The range of light-curve and periodogram shapes echoes that found for other clusters with K2, but fewer multiperiod stars may be an indication of the different noise characteristics of TESS, or a result of the source selection methods here. The distribution of P as a function of color as a proxy for mass fits nicely in

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Hiraga, Takahiro, Yasufumi Yamada, and Ryo Kobayashi. "Theoretical investigation of active listening behavior based on the echolocation of CF-FM bats." PLOS Computational Biology 18, no. 10 (2022): e1009784. http://dx.doi.org/10.1371/journal.pcbi.1009784.

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Bats perceive the three-dimensional environment by emitting ultrasound pulses from their nose or mouth and receiving echoes through both ears. To determine the position of a target object, it is necessary to know the distance and direction of the target. Certain bat species that use a combined signal of long constant frequency and short frequency modulated ultrasounds synchronize their pinnae movement with pulse emission, and this behavior has been regarded as helpful for localizing the elevation angle of a reflective sound source. However, the significance of bats’ ear motions remains unclear

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French, Michael M., Donald W. Burgess, Edward R. Mansell, and Louis J. Wicker. "Bulk Hook Echo Raindrop Sizes Retrieved Using Mobile, Polarimetric Doppler Radar Observations." Journal of Applied Meteorology and Climatology 54, no. 2 (2015): 423–50. http://dx.doi.org/10.1175/jamc-d-14-0171.1.

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AbstractPolarimetric radar observations obtained by the NOAA/National Severe Storms Laboratory mobile, X-band, dual-polarization radar (NOXP) are used to investigate “hook echo” precipitation properties in several tornadic and nontornadic supercells. Hook echo drop size distributions (DSDs) were estimated using NOXP data obtained from 2009 to 2012, including during the second Verification of the Origins of Rotation in Tornadoes Experiment (VORTEX2). Differences between tornadic and nontornadic hook echo DSDs are explored, and comparisons are made with previous observations of estimated hook ec

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Zhou, Bi, Shen, Wang, and Wang. "Hough Transform-Based Large Dynamic Reflection Coefficient Micro-Motion Target Detection in SAR." Sensors 19, no. 14 (2019): 3227. http://dx.doi.org/10.3390/s19143227.

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Special phase modulation of SAR echoes resulted from target rotation or vibration, is a phenomenon called the micro-Doppler (m-D) effect. Such an effect offers favorable information for micro-motion (MM) target detection, thereby improving the performance of the synthetic aperture radar (SAR) system. However, when there are MM targets with large differences in reflection coefficient, the weak reflection components will be difficult to be detected. To find a solution to this problem, we propose a novel algorithm. First, we extract and detect the strongest reflection component. By removing the s

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