scholarly journals Fourier analysis of spectral characteristics of a matrix photodetector in the frequency and time domain

2021 ◽  
pp. 39-46
Author(s):  
Stanislav Zienko ◽  
Vera Zhbanova
Keyword(s):  
Fourier Transform ◽  
Time Domain ◽  
Inverse Fourier Transform ◽  
Spectral Characteristics ◽  
Analytical Form ◽  
Time Characteristic ◽  
Absorption Of Light ◽  
The Matrix ◽  
Trans Ducer ◽  
Good Agreement

The purpose of this paper is to research the frequency and time characteristics of the photo-detector using the direct and inverse Fourier transform. The spectral characteristics of the matrix photodetector were selected as the object of research. For the channels of the trans-ducer it was found that the frequency spectrum consists of two elementary bands in the form of Gaussian curves. It was revealed that the spectra have super-broadband properties. The impulse (time) characteristic of the spectra is described by the equation in an analytical form, which is in good agreement with the calculation. The rise time of the transient response is 1.8–2.9 fs. The process of absorption of light is significantly influenced by dielectric relaxa-tion of the charge. The results obtained provide important information on the properties of the photodetector in the frequency and time domain.

A New Derivation of TGR with Naked Antenna in Lossy Medium

2013 ◽  
Vol 380-384 ◽  
pp. 4098-4102
Author(s):  
Xin Bo Qu ◽  
Bi Hua Zhou ◽  
Zheng Wan ◽  
Wei Shi ◽  
Xiao Gang Xie
Keyword(s):  
Fourier Transform ◽  
Frequency Domain ◽  
Integral Equations ◽  
Time Domain ◽  
Inverse Fourier Transform ◽  
Input Resistance ◽  
Grounding System ◽  
Grounding Resistance ◽  
Lossy Medium

A new derivation of Transient Grounding Resistance (TGR) has been proposed in this paper. Take grounding system as naked antenna in lossy medium, and then get the input resistance of naked antenna in a given frequency based on Helen current integral equations. With inverse Fourier transform, the resistance calculation equations can be translated from frequency domain to time domain. The result can be applied to design a new grounding system and to calculate its TGR .

Numerical Simulation on Fast Crack Propagation in a Bi-Material Involving interfaces under Dynamic Loading

2006 ◽  
Vol 324-325 ◽  
pp. 319-322
Author(s):  
Yue Sheng Wang ◽  
Jun Lei ◽  
Dietmar Gross
Keyword(s):  
Numerical Simulation ◽  
Crack Propagation ◽  
Boundary Element ◽  
Dynamic Loading ◽  
Time Domain ◽  
Domain Boundary ◽  
Dynamic Crack Propagation ◽  
Dynamic Crack ◽  
The Matrix ◽  
Good Agreement

The paper considers a bi-material with a crack propagating rapidly, penetrating or deflecting at the interface under dynamic loading. The hybrid time-domain boundary element method, together with the multi-region technique, is applied to simulate the dynamic process of propagation and penetration or deflection of the crack. Moving of the crack tip in the matrix, penetration and deflection of the crack at the interface, and propagation of the crack along the interface are controlled by criteria developed from the quasi-static ones. A bi-material rectangular plate with an edged crack under impact loading is computed and compared with the photoelastic experiments. Good agreement between numerical and experimental results implies that the present boundary element numerical method can provide an excellent simulation for the dynamic crack propagation in a bi-material involving interfaces.

On the problem of simulation of influence flooded compartment on the dynamics of the ship's navigation.

2021 ◽  
pp. 67-72
Author(s):  
В.В. Макарова ◽  
В.М. Набока ◽  
Ю.П. Потехин
Keyword(s):  
Fourier Transform ◽  
Frequency Domain ◽  
Time Domain ◽  
Inverse Fourier Transform ◽  
Simulation Models ◽  
Hydrodynamic Problem ◽  
The Stability ◽  
The Time Domain ◽  
Stability Of The Solution

В статье рассматривается возможность применения имеющихся в настоящее время решений задачи о влиянии динамического переливания жидкости в аварийных отсеках 2-й категории или успокоительных цистернах на качку судна в системах имитационного моделирования динамики плавания аварийных судов. Существующие решения получены в интересах исследования качки в частотной области и формально могут быть перенесены во временну́ю область, отвечающую существованию имитационных моделей, посредством обратного преобразования Фурье, что связано с определенными затруднениями. В работе показано, что при определенной формулировке гидродинамической задачи о колебаниях жидкости в отсеке или цистерне во временно́й области могут быть использованы непосредственно исходные уравнения. Выполнены расчеты, подтверждающие корректность такого подхода с позиций обеспечения устойчивости решения задачи и физической адекватности результатов реально наблюдаемым процессам. The article discusses the possibility of using the currently available solutions to the problem of the effect of dynamic fluid overflow in emergency compartments of the 2nd category or damping tanks on the pitching of a ship in systems for simulation of the dynamics of navigation of damaged ships. The existing solutions were obtained in the interests of studying the pitching in the frequency domain and can formally be transferred to the time domain corresponding to the existence of simulation models by means of the inverse Fourier transform, which is associated with certain difficulties. It is shown in the work that with a certain formulation of the hydrodynamic problem of fluid oscillations in a compartment or tank in the time domain, the original equations can be used directly. Calculations have been performed that confirm the correctness of this approach from the standpoint of ensuring the stability of the solution to the problem and the physical adequacy of the results to the actually observed processes.

scholarly journals Sampling signals with finite set of apertures

2021 ◽  
pp. 55-58
Author(s):  
V. I. Guzhov ◽  
◽  
I. O. Marchenko ◽  
E. E. Trubilina ◽  
A. A. Trubilin ◽  
...  
Keyword(s):  
Fourier Transform ◽  
Fourier Spectrum ◽  
Inverse Fourier Transform ◽  
Analytical Form ◽  
Generalized Functions ◽  
Signal Spectrum ◽  
Original Image ◽  
Analytical Expression ◽  
Image Sampling ◽  
Finite Set

The article discusses the issue of sampling continuous signals using a finite set of apertures. Using the apparatus of generalized functions, an analytical form of sampling is obtained for ideal sampling, for sampling a limited signal and for sampling a signal using a limited set of apertures. It is shown that the signal spectrum is the product of the signal spectrum at ideal sampling by some known factor, the influence of which can be eliminated. The type of this factor can be obtained if the type of aperture is known. The type of analytical expression differs from those known in the literature on image sampling. The use of an analytical expression for sampling can be used to reconstruct the original image from the image obtained with different sets of apertures. For this it is necessary to divide the Fourier spectrum of the sampled image by a factor depending on the selected aperture. Having received the inverse Fourier transform from it, you can get the original one

Dislocation structures around SiO2 Particles in aged Cu-Cr-SiO2

1978 ◽  
Vol 36 (1) ◽  
pp. 594-595
Author(s):  
N.J. Long ◽  
M.H. Loretto ◽  
C.H. Lloyd
Keyword(s):  
Flow Stress ◽  
Single Crystals ◽  
Room Temperature ◽  
Thin Foil ◽  
Age Hardening ◽  
Dispersion Strengthening ◽  
Accurate Picture ◽  
The Matrix ◽  
Very High ◽  
Good Agreement

IntroductionThere have been several t.e.m. studies (1,2,3,4) of the dislocation arrangements in the matrix and around the particles in dispersion strengthened single crystals deformed in single slip. Good agreement has been obtained in general between the observed structures and the various theories for the flow stress and work hardening of this class of alloy. There has been though some difficulty in obtaining an accurate picture of these arrangements in the case when the obstacles are large (of the order of several 1000's Å). This is due to both the physical loss of dislocations from the thin foil in its preparation and to rearrangement of the structure on unloading and standing at room temperature under the influence of the very high localised stresses in the vicinity of the particles (2,3).This contribution presents part of a study of the Cu-Cr-SiO2 system where age hardening from the Cu-Cr and dispersion strengthening from Cu-Sio2 is combined.

JOINT INTERPRETATION OF AIRBORNE ELECTROMAGNETIC DATA IN THE TIME DOMAIN AND FREQUENCY DOMAIN

2018 ◽  
Vol 12 (7-8) ◽  
pp. 76-83
Author(s):  
E. V. KARSHAKOV ◽  
J. MOILANEN
Keyword(s):  
Fourier Transform ◽  
Frequency Domain ◽  
Time Domain ◽  
Frequency Interval ◽  
Single Spectrum ◽  
Simultaneous Inversion ◽  
Homogeneous Half Space ◽  
Time Domain Data ◽  
The Time Domain

Тhe advantage of combine processing of frequency domain and time domain data provided by the EQUATOR system is discussed. The heliborne complex has a towed transmitter, and, raised above it on the same cable a towed receiver. The excitation signal contains both pulsed and harmonic components. In fact, there are two independent transmitters operate in the system: one of them is a normal pulsed domain transmitter, with a half-sinusoidal pulse and a small "cut" on the falling edge, and the other one is a classical frequency domain transmitter at several specially selected frequencies. The received signal is first processed to a direct Fourier transform with high Q-factor detection at all significant frequencies. After that, in the spectral region, operations of converting the spectra of two sounding signals to a single spectrum of an ideal transmitter are performed. Than we do an inverse Fourier transform and return to the time domain. The detection of spectral components is done at a frequency band of several Hz, the receiver has the ability to perfectly suppress all sorts of extra-band noise. The detection bandwidth is several dozen times less the frequency interval between the harmonics, it turns out thatto achieve the same measurement quality of ground response without using out-of-band suppression you need several dozen times higher moment of airborne transmitting system. The data obtained from the model of a homogeneous half-space, a two-layered model, and a model of a horizontally layered medium is considered. A time-domain data makes it easier to detect a conductor in a relative insulator at greater depths. The data in the frequency domain gives more detailed information about subsurface. These conclusions are illustrated by the example of processing the survey data of the Republic of Rwanda in 2017. The simultaneous inversion of data in frequency domain and time domain can significantly improve the quality of interpretation.

Performance of a Stirling Engine Regenerator Having Finite Mass

1986 ◽  
Vol 108 (4) ◽  
pp. 669-673 ◽  
Author(s):  
J. D. Jones
Keyword(s):  
Finite Element ◽  
Pressure Variation ◽  
Stirling Engine ◽  
System Model ◽  
Finite Mass ◽  
Element System ◽  
The Matrix ◽  
Cyclic Variations ◽  
Good Agreement ◽  
Engine Power

The performance of a Stirling engine regenerator subjected to sinusoidal mass flow rate and pressure variation is analyzed. It is shown that cyclic variations in the temperature of the matrix due to its finite mass lead to an increase in the apparent regenerator effectiveness, but a decrease in engine power. Approximate closed-form expressions for both of these effects are deduced. The results of this analysis are compared with the predictions of a finite-element system model, and good agreement is found.

Fabrication and Properties of Lignin/Castor Oil-Based Composites

2011 ◽  
Vol 311-313 ◽  
pp. 1535-1538 ◽  
Author(s):  
Hong Juan Wang ◽  
Hai Yan Xiao ◽  
Feng Qiang Sun ◽  
Jian Hua Zhang
Keyword(s):  
Fourier Transform ◽  
Electron Microscope ◽  
Free Radical ◽  
Composite Materials ◽  
Scanning Electron Microscope ◽  
Castor Oil ◽  
Morphology And Structure ◽  
The Matrix ◽  
Facile Route ◽  
Scanning Electron

Novel bio-based composites were developed from maleate castor oil (MACO) and lignin through free radical initiated copolymerization between MACO and diluent monomer styrene(St). The morphology and structure of the composites were characterized by Fourier transform infrared spectroscope (FTIR) and scanning electron microscope (SEM). The mechanical and thermal behaviors of the composites were investigated, which showed the incorporation of a little of lignin in the castor oil based polymer can enhance the tensile properties of the matrix polymer greatly. This work provides a facile route to prepare bio-based composite materials from castor oil and lignin and can be extended to prepare other bio-based materials from reproducible resources.

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