scholarly journals Characteristics of detecting the coherent system of selection of moving targets during the matching of the parameters of the square channels.

2021 ◽  
Author(s):  
S.I. Ziatdinov ◽  
Keyword(s):  
Spectral Density ◽  
Threshold Level ◽  
Average Frequency ◽  
Moving Object ◽  
Correct Detection ◽  
Coherent System ◽  
Selection System ◽  
Moving Targets ◽  
Adaptive Selection ◽  
Passive Interference

ntroduction. Operation of adaptive system of moving targets selection is considered, which is represented by single intermittent subtractor with coherent accumulator, which is tuned in frequency. System of moving targets selection is made in the form of two quadrature channels, in which high-frequency passive interference and signal from moving object are converted to video frequency with subsequent rejection, accumulation and comparison with threshold level. Setting the task. Investigation of the effect of the inevitable in practice amplitude and phase misalignments of quadrature channel parameters on the detection characteristics of the adaptive selection system of moving targets. Method. Method of complex variable is used, in which passive interference and signal from moving object at input and output of adaptive selection system of moving targets are presented in the form of pair of real components shifted in phase by ninety degrees. Results. Models of passive interference and signal from moving object are presented taking into account possible in practice amplitude and phase mismatches of quadrature channels parameters. The structure of the processing device is shown, which includes a series-connected generator of quadrature components of passive interference and a signal from a moving object, an adaptive cutting filter in the form of a single intermittent subtraction circuit with a frequency-tuned rejection zone, an adaptive coherent accumulator and a threshold device. Expressions are obtained for complex correlation functions of passive interference and signal from moving object at output of coherent accumulator taking into account inevitable amplitude and phase mismatches of quadrature channels parameters. Dependencies of probability of correct detection of signal from moving object against the background of passive interference from value of deviation of transmission coefficients of quadrature channels and phase mismatch of reference voltages for different values of average frequency of spectral density of passive interference are calculated and constructed. Conclusion. Significant dependence of probability of correct detection of signal from moving object on average frequency of spectral density of passive interference, as well as amplitude and phase mismatches of quadrature channels parameters is shown.

scholarly journals Influence of Mismatch of Parameters of Quadrature Channels on the Work of the Adaptive Selection System for Moving Targets

2020 ◽  
Vol 23 (3) ◽  
pp. 25-31
Author(s):  
S. I. Ziatdinov
Keyword(s):  
Noise Suppression ◽  
Target Selection ◽  
Average Frequency ◽  
Complex Conjugate ◽  
Selection System ◽  
Moving Targets ◽  
Adaptive Selection ◽  
Signal Suppression ◽  
Passive Noise ◽  
Selection Of

Introduction. The paper considers the operation of an adaptive selection system for moving targets, represented by a one-time multi-period subtractor. The system of selection of moving targets is made in the form of two quadrature channels, in which high-frequency input radio signals are converted to video frequency. Goal. Investigation of the system of selection of moving targets in the conditions of amplitude and phase misalignment of quadrature channels. Aim. The study of the operation of the moving targets selection system in the conditions of amplitude and phase mismatches of quadrature channels. Materials and methods. The method of complex variable is used, in which the input and output signals of the adaptive selection system for moving targets are represented as a pair of complex-conjugate components. Results. An expression is obtained for the frequency transfer function of an adaptive passive noise suppression system with a variable cut-off zone relative to the average frequency of the spectrum of interference signals. The influence of almost unavoidable amplitude and phase mismatches in the characteristics of quadrature channels is studied. Expressions are obtained for the dispersion of output noise signals of the considered system of moving targets with amplitude and phase misalignment of quadrature channels. Analytical relations for the coefficients of passive interference suppression are presented. The dependences of the jamming signal suppression coefficients were calculated and constructed depending on the deviation of the transmission coefficients of quadrature channels and the phase misalignment of the reference voltages for different values of the average frequency of the passive noise spectrum. Conclusion. The essential dependence of the jamming signal suppression coefficient on their average frequency, as well as amplitude and phase misalignments of quadrature channels is shown. The proposed research method allows us to evaluate the effect of misalignment of quadrature channels on the operation of a moving target selection system using high-order cutting filters.

scholarly journals Superconducting coherence length of hole-doped cuprates obtained from electron–boson spectral density function

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jungseek Hwang
Keyword(s):  
Spectral Density ◽  
Coherence Length ◽  
Cooper Pair ◽  
Average Frequency ◽  
Spin Fluctuations ◽  
Fermi Velocity ◽  
Cooper Pairs ◽  
Spectroscopic Techniques ◽  
Microscopic Mechanism ◽  
Superconducting Coherence Length

AbstractElectron–boson spectral density functions (EBSDFs) can be obtained from measured spectra using various spectroscopic techniques, including optical spectroscopy. EBSDFs, known as glue functions, are suggested to have a magnetic origin. Here, we investigated EBSDFs obtained from the measured optical spectra of hole-doped cuprates with wide doping levels, from underdoped to overdoped cuprates. The average frequency of an EBSDF provides the timescale for the spin fluctuations to form Cooper pairs. This timescale is directly associated with retarded interactions between electrons. Using this timescale and Fermi velocity, a reasonable superconducting coherence length, which reflects the size of the Cooper pair, can be extracted. The obtained coherence lengths were consistent with those measured via other experimental techniques. Therefore, the formation of Cooper pairs in cuprates can be explained by spin fluctuations, the timescales of which appear in EBSDFs. Consequently, EBSDFs provide crucial information on the timescale of the microscopic mechanism of Cooper pair formation.

scholarly journals Superconducting Coherence Length of Hole-doped Cuprates Obtained From Electron-boson Spectral Density Function

2021 ◽  
Author(s):  
Jungseek Hwang
Keyword(s):  
Spectral Density ◽  
Coherence Length ◽  
Cooper Pair ◽  
Average Frequency ◽  
Spin Fluctuations ◽  
Fermi Velocity ◽  
Cooper Pairs ◽  
Spectroscopic Techniques ◽  
Microscopic Mechanism ◽  
Superconducting Coherence Length

Abstract Electron{boson spectral density functions (EBSDFs) can be obtained from measured spectra using various spectroscopic techniques, including optical spectroscopy. EBSDFs, known as glue functions, have a magnetic origin. Here, we investigated EBSDFs obtained from the measured optical spectra of hole-doped cuprates with wide doping levels, from underdoped to overdoped cuprates. The average frequency of an EBSDF provides the timescale for the spin fluctuations to form Cooper pairs. This timescale is directly associated with retarded interactions betweenelectrons. Using this timescale and Fermi velocity, a reasonable superconducting coherence length, which reflects the size of the Cooper pair, can be extracted. The obtained coherence lengths were consistent with those measured via other experimental techniques. Therefore, the formation of Cooper pairs in cuprates can be explained by spin fluctuations, the timescales of which appear in EBSDFs. Consequently, EBSDFs provide crucial information on the timescale of the microscopic mechanism of Cooper pair formation.

Videogrammetry and one of its applications

2015 ◽  
Author(s):  
Daniela Velichova
Keyword(s):  
Moving Objects ◽  
Moving Object ◽  
Moving Targets ◽  
3 Dimensional ◽  
Video Cameras ◽  
Basic Concepts ◽  
Point Positioning

Videogrammetry is presented in the paper as a new branch of photogrammetry that offers some effective algorithms for direct reconstruction of moving objects from video records. Videogrammetry can solve two major problems: reconstruction of surfaces (body, face, etc.) and determination of trajectories of moving targets. Videogrammetry can inspect permanently provided and stored records taken by video cameras, so it can be used for additional measurements and re-measurements, and verification at any time. Basic concepts and algorithms for reconstruction of real dimensions of a 3 dimensional moving object from its video records are introduced. Basic formulas for algorithms of point positioning and calibration calculation are explained.

The Time Course of Direction Specification in Brief Interceptive Actions

2010 ◽  
Vol 57 (4) ◽  
pp. 292-300 ◽  
Author(s):  
Welber Marinovic ◽  
Annaliese M. Plooy ◽  
James R. Tresilian
Keyword(s):  
Time Course ◽  
Motor Program ◽  
Motor Preparation ◽  
Moving Object ◽  
Movement Direction ◽  
Moving Targets ◽  
Movement Onset ◽  
Short Intervals ◽  
Interceptive Actions ◽  
Direction Information

In fastball sports such as baseball and tennis people are required to produce accurate responses following brief observations of the ball. This limits the time available to prepare the movement. To cope with constrained viewing periods which precede the interception of fast approaching balls, performers are likely to prepare their responses in advance. Although motor preparation may begin before the moving object is seen, accuracy requires that certain program parameters are determined from observations of the target. The aim of the experiment reported here was to determine the last moment at which information about the direction of the target can be incorporated into a motor program. The empirical protocol used in this study allowed us to examine whether new direction information is incorporated discretely or continuously into the program during short intervals prior to movement onset (MO) – the preparation interval. Participants were trained to hit moving targets at two directions with movements of a specific duration (180 ms). This method permitted an estimate of MO. Preparation intervals were controlled by issuing a stimulus cue for movement direction at various times prior to the estimated MO. Results showed that direction information could be fully incorporated into the program with a preparation interval as brief as 250 ms. In addition, the results indicated that direction was specified predominantly in a discrete fashion even at short preparation intervals.

Systematic effects in observed parallaxes

1978 ◽  
Vol 48 ◽  
pp. 31-35
Author(s):  
R. B. Hanson
Keyword(s):  
Error Estimates ◽  
Zero Point ◽  
Absolute Zero ◽  
Apparent Magnitude ◽  
Coherent System ◽  
Preliminary Results ◽  
General Catalogue ◽  
Systematic Effects ◽  
New Evidence ◽  
Right Ascension

Several outstanding problems affecting the existing parallaxes should be resolved to form a coherent system for the new General Catalogue proposed by van Altena, as well as to improve luminosity calibrations and other parallax applications. Lutz has reviewed several of these problems, such as: (A) systematic differences between observatories, (B) external error estimates, (C) the absolute zero point, and (D) systematic observational effects (in right ascension, declination, apparent magnitude, etc.). Here we explore the use of cluster and spectroscopic parallaxes, and the distributions of observed parallaxes, to bring new evidence to bear on these classic problems. Several preliminary results have been obtained.

Maternal DDAVP-induced hyponatremia: Threshold level for fetal urinary diuresis

1998 ◽  
Vol 5 (1) ◽  
pp. 151A-151A
Author(s):  
M NIJLAND ◽  
T ROBERTS ◽  
M CURRAN ◽  
M ROSS
Keyword(s):  
Threshold Level
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