Molecular quantum beats. High-resolution spectroscopy in the time domain

1992 ◽  
Vol 25 (2) ◽  
pp. 65-71 ◽  
Author(s):  
Herbert Bitto ◽  
J. Robert Huber
Keyword(s):  
High Resolution ◽  
Time Domain ◽  
High Resolution Spectroscopy ◽  
Quantum Beats ◽  
The Time Domain

High-resolution spectroscopy of inhomogeneously broadened Raman resonances by time-domain CARS

2002 ◽  
Author(s):  
V. G. Arakcheev ◽  
V. B. Morozov ◽  
A. N. Olenin ◽  
V. G. Tunkin ◽  
D. V. Yakovlev
Keyword(s):  
High Resolution ◽  
Time Domain ◽  
High Resolution Spectroscopy

scholarly journals Focusing High-Resolution Airborne SAR with Topography Variations Using an Extended BPA Based on a Time/Frequency Rotation Principle

2018 ◽  
Vol 10 (8) ◽  
pp. 1275 ◽  
Author(s):  
Chunhui Lin ◽  
Shiyang Tang ◽  
Linrang Zhang ◽  
Ping Guo
Keyword(s):  
High Resolution ◽  
Time Domain ◽  
Phase Error ◽  
Projection Algorithm ◽  
Geometric Distortion ◽  
Back Projection ◽  
Time Frequency ◽  
Phase Errors ◽  
Airborne Sar ◽  
The Time Domain

With the increasing requirement for resolution, the negligence of topography variations causes serious phase errors, which leads to the degradation of the focusing quality of the synthetic aperture (SAR) imagery, and geometric distortion. Hence, a precise and fast algorithm is necessary for high-resolution airborne SAR. In this paper, an extended back-projection (EBP) algorithm is proposed to compensate the phase errors caused by topography variations. Three-dimensional (3D) variation will be processed in the time-domain for high-resolution airborne SAR. Firstly, the quadratic phase error (QPE) brought by topography variations is analyzed in detail for high-resolution airborne SAR. Then, the key operation, a time-frequency rotation operation, is applied to decrease the samplings in the azimuth time-domain. Just like the time-frequency rotation of the conventional two-step approach, this key operation can compress data in an azimuth time-domain and it reduces the computational burden of the conventional back-projection algorithm, which is applied lastly in the time-domain processing. The results of the simulations validate that the proposed algorithm, including frequency-domain processing and time-domain processing can obtain good focusing performance. At the same time, it has strong practicability with a small amount of computation, compared with the conventional algorithm.

scholarly journals Application of Time-Domain Full Waveform Inversion to Cross-Hole Radar Data Measured at Xiuyan Jade Mine, China

Sensors ◽  
2018 ◽  
Vol 18 (9) ◽  
pp. 3114 ◽  
Author(s):  
Sixin Liu ◽  
Xintong Liu ◽  
Xu Meng ◽  
Lei Fu ◽  
Qi Lu ◽  
...  
Keyword(s):  
High Resolution ◽  
Ray Tracing ◽  
Time Domain ◽  
Waveform Inversion ◽  
Synthetic Data ◽  
Radar Data ◽  
Liaoning Province ◽  
Full Waveform Inversion ◽  
Full Waveform ◽  
The Time Domain

Xiuyan Jade, produced in Xiuyan County, Liaoning Province, China is one of the four famous jade in China. King Jade, which is deemed the largest jade body of the world, was broken out from a hill. The local government planned to build a tourism site based on the jade culture there. The purpose of the investigation was to evaluate the stability of subsurface foundation, and the possible positions of mined-out zones to prevent the further rolling of the jade body. Cross-hole radar tomography is the key technique in the investigation. Conventional travel time and attenuation tomography based on ray tracing theory cannot provide high-resolution images because only a fraction of the measured information is used in the inversion. Full-waveform inversion (FWI) can provide high-resolution permittivity and conductivity images because it utilizes all the information provided by the radar signals. We deduce the gradient expression of the time-domain FWI with respect to the permittivity and conductivity using a method that is different from that of the previous work and realize the FWI algorithm that can simultaneously update the permittivity and conductivity by using the conjugate gradient method. Inverted results from synthetic data show that time-domain FWI can significantly improve the resolution compared with the ray-based tomogram methods. FWI can distinguish targets that are as small as one-half to one-third wavelength and the inverted physical values are closer to the real ones than those provided by the ray tracing method. We use the FWI algorithm to the field data measured at Xiuyan jade mine. Both the inverted permittivity and conductivity can comparably delineate four mined-out zones, which exhibit low-permittivity and low-conductivity characteristics. Furthermore, the locations of the interpreted mined-out zones are in good agreement with the existing mining channels recorded by geological data.

scholarly journals Radon Transform Based on Waveform for AVO-Preserving Data Construction

2021 ◽  
Vol 11 (19) ◽  
pp. 9112
Author(s):  
Shengchao Wang ◽  
Liguo Han ◽  
Xiangbo Gong ◽  
Pan Zhang
Keyword(s):  
High Resolution ◽  
Time Domain ◽  
Radon Transform ◽  
Conjugate Gradient ◽  
Seismic Waves ◽  
A Priori ◽  
Computation Time ◽  
Amplitude Variation With Offset ◽  
The Time Domain ◽  
Valid Criterion

The traditional hyperbolic Radon transform suffers from the major problem of how to both obtain a high resolution and preserve the amplitude variation with offset (AVO). In the Radon domain, high resolution (sparseness) is a valid criterion. However, if a sparse model is obtained in the Radon domain due to averaging along the offset direction, then it is not possible to preserve the AVO in the inversion data. In addition, hyperbolic Radon transform has a time-variant kernel based on a traditional iterative algorithm, the conjugate gradient (CG), which requires significant computation time. To solve these problems, we propose a Radon transform based on waveform that contains both cycle and amplitude characteristics of seismic waves. The new transform entails creating an upper envelope for the seismic data and computing a preliminary forward Radon transform in the time domain. The forward Radon transform incorporates a priori information by measuring the energy of each slowness (p) trace to obtain the high-resolution result of the Radon domain. For AVO preserving, the proposed method uses polynomials to describe the AVO characteristics in the inverse Radon transform based on the least-squares inversion. Besides amplitude preserving and high resolution, the proposed method avoids using CG and greatly reduces the cost of computing hyperbolic Radon transform in the time domain. In applications to both synthetic and field data, waveform Radon transform (WRT) has a better performance than the conjugate gradient Radon transform (CGRT).

scholarly journals A generic gust definition and detection method based on wavelet-analysis

2019 ◽  
Vol 16 ◽  
pp. 143-148
Author(s):  
Helge Knoop ◽  
Felix Ament ◽  
Björn Maronga
Keyword(s):  
High Resolution ◽  
Wavelet Analysis ◽  
Wind Velocity ◽  
Time Domain ◽  
Velocity Measurement ◽  
Measurement Data ◽  
Direct Link ◽  
Velocity Signal ◽  
Characteristic Period ◽  
The Time Domain

Abstract. Wind gusts can have destructive effects on many structures and objects deemed valuable to humans. The aviation industry, for example, views gusts as a major hazard. Their destructive effect is proportional to the momentum that a specific gust imposes onto an object. The actual definition of a gust has a strong influence on how its impact can be quantified. Existing gust definitions, however, are largely based on fixed parameters describing shape requirements and thresholds and are often developed only for specific use cases. These gust definitions do not provide a direct link to the physical impact a particular gust has on a structure or object. The overall goal of this study is to provide such a direct link. The application of a wavelet-analysis to a turbulence-resolving wind velocity signal allows for the localization of signal amplitudes in the period as well as in the time domain. In this paper, we use wavelet-analysis in order to develop a straight-forward method of deriving information about gusts from a wind velocity signal. In order to define what a particular gust might be, we suggest the specification of a characteristic period and amplitude in the time-domain. We define a generic gust as a section of a wind velocity signal, where the wavelet-analysis detects that characteristic amplitude to be matched or exceeded within that characteristic period. The characteristic amplitudes and periods are generic and span a two-dimensional space of generic gust definitions. The method can be applied to turbulence resolving simulation data as well as high-resolution wind velocity measurement data. It can detect gusts of any shape, it is unbiased regarding any specific use case and invariant to changes of the mean wind. We provide a detailed description of the method, its capabilities and demonstrate its application to high resolution wind velocity measurement data.

scholarly journals Comparison of modelled and observed responses of a glacier snowpack to ground-penetrating radar

2003 ◽  
Vol 37 ◽  
pp. 293-297 ◽  
Author(s):  
Jack Kohler ◽  
John C. Moore ◽  
Elisabeth Isaksson
Keyword(s):  
High Resolution ◽  
Time Domain ◽  
Ground Penetrating Radar ◽  
Ice Core ◽  
Reflection Coefficients ◽  
Order Of Magnitude ◽  
The Time Domain ◽  
Ground Penetrating ◽  
Physical And Chemical ◽  
Firn Core

AbstractThe upper 10 m of the firn of a Svalbard glacier is imaged along the centre line using a 500 MHz ground-penetrating radar, and a 10 m firn core taken along the profile. Complex reflection coefficients are calculated from the high-resolution capacitance and conductance measurements made on the snow core. The reflection coefficient depth series is converted to the time domain and convolved with model radar monopulses to synthesize traces that compare well with radar traces recorded near the ice core. Differences are probably due to cm-scale physical and chemical inhomogeneities that are smoothed when imaged by the radar beam, which integrates information over areas that are of the same order of magnitude as the depth to the layer.

scholarly journals Global distributions of C<sub>2</sub>H<sub>6</sub>, C<sub>2</sub>H<sub>2</sub>, HCN, and PAN retrieved from MIPAS reduced spectral resolution measurements

2011 ◽  
Vol 4 (4) ◽  
pp. 5389-5424
Author(s):  
A. Wiegele ◽  
N. Glatthor ◽  
M. Höpfner ◽  
U. Grabowski ◽  
S. Kellmann ◽  
...  
Keyword(s):  
High Resolution ◽  
Spectral Resolution ◽  
Time Domain ◽  
Measurement Noise ◽  
Uncertain Parameters ◽  
Vertical Profiles ◽  
Retrieval Strategy ◽  
Mixing Ratios ◽  
The Time Domain ◽  
Nominal Mode

Abstract. Vertical profiles of mixing ratios of C2H6, C2H2, HCN, and PAN were retrieved from MIPAS reduced spectral resolution nominal mode limb emission measurements. The retrieval strategy followed that of the analysis of MIPAS high resolution measurements, with occasional adjustments to cope with the reduced spectral resolution under which MIPAS is operated since 2005. Largest mixing ratios are found in the troposphere, and reach 1.2 ppbv for C2H6, 1 ppbv for HCN, 600 pptv for PAN, and 450 pptv for C2H2. The estimated precision in case of significantly enhanced mixing ratios (including measurement noise and propagation of uncertain parameters randomly varying in the time domain) and altitude resolution are typically 10 %, 3–4.5 km for C2H6, 15 %, 4–6 km for HCN, 6 %, 2.5–3.5 km for PAN, and 7 %, 2.5–4 km for C2H2.

scholarly journals Simulation and Measurement Methods for RCS Estimations of a Scale Model Airplane

2016 ◽  
Vol 5 (1-2) ◽  
Author(s):  
Naobumi Michishita ◽  
Nguyen Quoc Dinh ◽  
Yoshihide Yamada
Keyword(s):  
High Resolution ◽  
Time Domain ◽  
High Speed ◽  
Time Domain Analysis ◽  
Domain Analysis ◽  
Scale Model ◽  
Object A ◽  
Electromagnetic Simulations ◽  
Compact Range ◽  
The Time Domain

In a military context, the radar cross section (RCS) of an airplane is a very important subject. For an RCS estimation object, a scaled-down model is often employed for ease of measurements. Recently, electromagnetic simulations of the RCS has become very convenient because of developments in high-speed calculation methods such as MLFMM and HOBF in electromagnetic simulators employing the MoM algorithm. As for the measurements, high-resolution measurements via the time domain analysis are promising. In this paper, important estimation expressions for use with a scale model are briefly explained. In terms of calculations, comparisons are drawn between the actual calculation abilities of MoM, MLFMM, and HOBF at 18 GHz for a 1/48-scale model. In terms of measurement, a high-resolution measurement system employing a compact range and time domain analysis that is used in this study is explained. Next, the calculated and measured results are compared in order to show the accuracy of the obtained results. The results in vertical and horizontal planes of a scale model are shown at vertical and horizontal polarizations. Moreover, using the calculation method to determine estimates at higher frequencies is also investigated in order to obtain the practical RCS value of a real-sized airplane

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