scholarly journals The θ–θ diagram: transforming pulsar scintillation spectra to coordinates on highly anisotropic interstellar scattering screens

2020 ◽  
Vol 500 (1) ◽  
pp. 1114-1124
Author(s):  
Tim Sprenger ◽  
Olaf Wucknitz ◽  
Robert Main ◽  
Daniel Baker ◽  
Walter Brisken
Keyword(s):  
Multipath Propagation ◽  
Amplitude Distribution ◽  
One Dimensional ◽  
Doppler Shifts ◽  
Analysis Technique ◽  
Interstellar Scattering ◽  
Dimensional Distribution ◽  
Curvature Parameter ◽  
Angular Coordinates ◽  
Thin Screen

ABSTRACT We introduce a novel analysis technique for pulsar secondary spectra. The power spectrum of pulsar scintillation (referred to as the ‘secondary spectrum’) shows differential delays and Doppler shifts due to interference from multipath propagation through the interstellar medium. We develop a transformation that maps these observables to angular coordinates on a single thin screen of phase-changing material. This transformation is possible without degeneracies in the case of a one-dimensional distribution of images on this screen, which is often a successful description of the phenomenon. The double parabolic features of secondary spectra are transformed into parallel linear features, whose properties we describe in detail. Furthermore, we introduce methods to measure the curvature parameter and the field amplitude distribution of images by applying them to observations of PSR B0834+06. Finally, we extend this formalism to two-dimensional distributions of images on the interstellar screen.

Quasi-one-dimensional distribution of macropores in anodically etched uniaxially stressed silicon plates

2003 ◽  
Vol 29 (3) ◽  
pp. 226-229 ◽  
Author(s):  
V. I. Emel’yanov ◽  
K. I. Eremin ◽  
V. V. Starkov ◽  
E. Yu. Gavrilin
Keyword(s):  
One Dimensional ◽  
Dimensional Distribution ◽  
Stressed Silicon

Analysis of Rayleigh-wave multipath propagation at LASA

1970 ◽  
Vol 60 (5) ◽  
pp. 1701-1731 ◽  
Author(s):  
Jack Capon
Keyword(s):  
Rayleigh Waves ◽  
Multipath Propagation ◽  
Continental Margins ◽  
Period Range ◽  
Analysis Technique ◽  
High Resolution Analysis ◽  
Resolution Analysis ◽  
Propagation Paths ◽  
Using Data ◽  
Almost All

Abstract An investigation has been made of the multipath propagation of Rayleigh waves by using data obtained from the large aperture seismic array (LASA). The use of the LASA in conjunction with a high-resolution analysis technique provides a greater angular resolution and accuracy than was previously possible for the analysis of the multipath propagation. Measurements have been made of this phenomenon for the Rayleigh waves of 26 events distributed at various azimuths and distances from LASA. On the bas of these measurements reasonably good conjectures are made concerning the actual propagation paths for groups in the 20- to 40-sec period range. It is shown that in almost all cases these propagation paths can be associated with refractions and reflections at the continental margins.

Assimilation of SSM/I and GOES Humidity Retrievals with a One-Dimensional Variational Analysis Scheme

1995 ◽  
Vol 34 (7) ◽  
pp. 1536-1550 ◽  
Author(s):  
Godelieve Deblonde ◽  
Louis Garand ◽  
Pierre Gauthier ◽  
Christopher Grassotti
Keyword(s):  
Variational Analysis ◽  
Lower Troposphere ◽  
Precipitable Water ◽  
Error Variance ◽  
Specific Humidity ◽  
One Dimensional ◽  
Brightness Temperatures ◽  
Analysis Technique ◽  
Analysis Scheme ◽  
The Tropics

Abstract Total precipitable water (TPW) retrieved from Special Sensor Microwave/lmager (SSM/I) brightness temperatures and specific humidity retrieved from Geostationary Operational Environmental Satellite (GOES) radiances are assimilated using a one-dimensional (ID) variational analysis technique. The study is divided into two parts. First, collocations with radiosondes are performed to arm the quality of the satellite water vapor retrievals. Collocations are also performed with 6-h forecast Acids. Second, SSM/I TPW and GOES specific humidity are assimilated using a ID variational analysis technique that minimizes the error variance of the analyzed field. A global collocation study over the oceans for SSM/I TPW retrievals and 6-h forecasts of TPW shows that the rmse (with respect to radiosondes) are, respectively, 4.7 and 5.0 kg m−2. A separate collocation study over both the oceans and land for GOES retrieved TPW and 6-h forecasts of TPW yields rmse of 4.6 and 4.4 kg m−2, respectively, in the midlatitudes and 6.8 and 5.9 kg m−2 in the Tropics. The reduction of the 6-h forecast rmse when assimilating SSM/I TPW is 1 kg m−2, which is a reduction of 20% in the rmse. When GOES retrievals of specific humidity are assimilated, the elective reduction is 0.6 kg m−2. It is shown that in the upper levels of the troposphere (above 600 mb), the error reduction of specific humidity is largely due to the GOES retrievals, whereas in the lower troposphere (850 and 700 mb), the reduction is mostly due to the SSM/I TPW. This emphasizes the complementarity of the information contained at different wavelengths and the advantage of using multisensor retrievals in data analysis.

Determination of one-dimensional distribution of14C-labelled compounds

1988 ◽  
Vol 126 (6) ◽  
pp. 443-453 ◽  
Author(s):  
R. Rexa ◽  
I. Kron ◽  
P. Kralik ◽  
R. Tykva
Keyword(s):  
One Dimensional ◽  
Dimensional Distribution

Transfer Functions of One-Dimensional Distributed Parameter Systems by Wave Approach

2006 ◽  
Vol 129 (2) ◽  
pp. 193-201 ◽  
Author(s):  
B. Kang
Keyword(s):  
Transfer Function ◽  
Frequency Response ◽  
Wave Reflection ◽  
Transfer Functions ◽  
Distributed Parameter Systems ◽  
Distributed Parameter ◽  
Complex Frequency ◽  
Reflection And Transmission ◽  
One Dimensional ◽  
Analysis Technique

An alternative analysis technique, which does not require eigensolutions as a priori, for the dynamic response solutions, in terms of the transfer function, of one-dimensional distributed parameter systems with arbitrary supporting conditions, is presented. The technique is based on the fact that the dynamic displacement of any point in a waveguide can be determined by superimposing the amplitudes of the wave components traveling along the waveguide, where the wave numbers of the constituent waves are defined in the Laplace domain instead of the frequency domain. The spatial amplitude variations of individual waves are represented by the field transfer matrix and the distortions of the wave amplitudes at point discontinuities due to constraints or boundaries are described by the wave reflection and transmission matrices. Combining these matrices in a progressive manner along the waveguide using the concepts of generalized wave reflection and transmission matrices leads to the exact transfer function of a complex distributed parameter system subjected to an externally applied force. The transient response solution can be obtained through the Laplace inversion using the fixed Talbot method. The exact frequency response solution, which includes infinite normal modes of the system, can be obtained in terms of the complex frequency response function from the system’s transfer function. This wave-based analysis technique is applicable to any one-dimensional viscoelastic structure (strings, axial rods, torsional bar, and beams), in particular systems with multiple point discontinuities such as viscoelastic supports, attached mass, and geometric/material property changes. In this paper, the proposed approach is applied to the flexural vibration analysis of a classical Euler–Bernoulli beam with multiple spans to demonstrate its systematic and recursive formulation technique.

scholarly journals High-precision measurement of velocity profiles in laser-created chlorine plasma

1995 ◽  
Vol 13 (4) ◽  
pp. 503-510 ◽  
Author(s):  
O. Renner ◽  
E. Krouský ◽  
T. Mißalla ◽  
E. Förster ◽  
G. Hölzer
Keyword(s):  
Spectral Lines ◽  
Plasma Parameters ◽  
High Precision Measurement ◽  
One Dimensional ◽  
Electron Temperature Gradient ◽  
Spatially Resolved ◽  
Doppler Shifts ◽  
Velocity Gradients ◽  
Marquardt Algorithm ◽  
The One

A vertical dispersion variant of the Johann spectrometer has been used to record the highresolution X-ray spectra of the chlorine He-like resonance line group emitted from lowradiance plasma. The emission profiles were measured at two observation angles and decomposed into single spectral lines by using a fit based on the Levenberg-Marquardt algorithm. The results of computerized analysis of the one-dimensional (1-D) spatially resolved spectra were used to evaluate the distribution of the main plasma parameters. The electron temperature gradient 7.5·104 eV cm-1 was computed by modeling the measured spectra with the collisional-radiative package RATION. The blowoff maximum velocities 4.2–6.1·107 cm s-1 and the velocity gradients 0.9–1.6·109 s-1 were determined from the Doppler shifts of individual spectral lines within their different spatial extent.

ONE DIMENSIONALITY OF DEUTERON VELOCITY DISTRIBUTION FOR CLUSTER-IMPACT FUSION

1992 ◽  
Vol 06 (10) ◽  
pp. 573-579 ◽  
Author(s):  
YEONG E. KIM ◽  
JIN-HEE YOON ◽  
ROBERT A. RICE ◽  
MARIO RABINOWITZ
Keyword(s):  
Energy Spectrum ◽  
Velocity Distribution ◽  
Proton Energy ◽  
Three Dimensional ◽  
Beam Direction ◽  
One Dimensional ◽  
Proton Energy Spectrum ◽  
Dimensional Distribution

In cluster-impact fusion, the width of the proton energy spectrum gives information about the temperature of the fusing deuterons, and its shape reflects the dimensionality of their velocity distribution. The observed symmetrical spectrum implies a one-dimensional distribution, whereas a three-dimensional distribution would result in a skewed spectrum. One dimensionality implies either extremely rapid thermalization in the beam direction, or the possibility of beam ion fusion.

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