Academic literature on the topic 'Amplitude and phase characteristics of signal'
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Journal articles on the topic "Amplitude and phase characteristics of signal"
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Gusenitsa, Yaroslav N., Aleksandr L. Snegirev, and Sergey A. Pokotilo. "Study of the characteristics of a radio photon device for determining the phase difference of a radar signals." Izmeritel`naya Tekhnika, no. 2 (2021): 38–42. http://dx.doi.org/10.32446/0368-1025it.2021-2-38-42.
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The paper considers the problem of accurate calculation of the phase of the radar signal in relation to the receiving phased antenna arrays. Methods for determining the phase difference based on a comparison of the received signal with the local oscillator signal are listed, as well as a method based on the use of a radio-photon analog-to-digital converter for the output signal of the receiving phased antenna array. Their disadvantages are indicated. A method and a radio photon device are proposed that are devoid of these disadvantages. The method allows you to calculate the phase difference of the radar signal at the output of the electro-optical modulator and the output signal of the photodetector, taking into account the known values of the amplitudes and phase difference of the microwave signals at the input of the receiving elements of the phased antenna array. The radio-photon device allows you to implement this method and, unlike the known analogues, is based on the use of two parallel-connected electro-optical modulators constructed according to the scheme of the Mach-Zehnder interferometer. It is shown that the proposed radio photon device provides a higher accuracy of determining the phase of the radar signal in comparison with existing analogues. At the end of the work, an analysis of the results of experimental studies using the proposed method and a radio photon device is presented. According to the results of the experiment, it was found that the phase and phase differences vary linearly, and their maximum reaches π. In addition, the square of the amplitude of the optical signal at the input of the photon-electronic unit is proportional to the phase difference and inversely proportional to the ratio of the amplitudes of the output signals of the adjacent receiving elements of the phased antenna arrays.
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Artyushenko, V. M., and V. I. Volovach. "Determination of the Probability Density Function of the Mixture Signal and Additive Noise under Influence of Multiplicative Noise." Journal of Physics: Conference Series 2096, no. 1 (2021): 012154. http://dx.doi.org/10.1088/1742-6596/2096/1/012154.
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Abstract Issues related to effect of multiplicative (modulating) (otherwise amplitude distortions) and additive noises on processed signal are considered. Analysis of statistical characteristics of probability density function (PDF) of instantaneous signal values against background of modulating interference is carried out. Expressions of the joint PDF envelope, phase and instantaneous signal values are obtained, for the case of only phase distortions, as well as the case when fluctuations in amplitude and phase are independent of each other. It is noted that in the second case, with the independence of phase and amplitude distortions, the PDF of the signal, first of all, is determined by the PDF of its instantaneous values and practically does not depend on the PDF of the signal phase. Expressions are obtained for the PDF useful signal and the most common PDF envelope when affecting the signal with modulating noise for deep phase distortions and for its uniform distribution over the interval (0, 2π). In addition, for the case of some functional relationship of phase and amplitude fluctuations, the expression for PDF instantaneous signal values is defined. The presence of such a functional connection allows calculating the PDF of the signal through the statistical characteristics of its envelope. It is obtained that PDF of mixture of signal and additive noise contains arbitrary distribution of phase and amplitude, as well as arbitrary law of distribution of envelope of processed signal. It is obtained that weight coefficients are determined by derivative of characteristic function of amplitude distortion in case when PDFs of said mixture are distributed according to normal law and functional connection exists between amplitude and phase distortions.
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Chai, Meng Yu, Li Chan Li, Yong Quan Li, Wen Jie Bai, and Quan Duan. "Investigation on Acoustic Emission Characteristics from Q345R during Fatigue Crack Propagation." Applied Mechanics and Materials 331 (July 2013): 61–64. http://dx.doi.org/10.4028/www.scientific.net/amm.331.61.
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The fatigue crack propagation process of specimen made from Q345R was monitored by acoustic emission (AE) equipment. The AE characteristic of the specimen generated during the fatigue crack propagation was obtained by parameter analysis method and wavelet transform method .The results show that the fatigue crack growth curve comprises four phases of the crack generation phase, the low-speed crack propagation phase, the high-speed crack propagation phase and the fracture phase, and the variation of signal parameters presents the similar tendency to the fatigue crack growth rate. The values of signal parameters, such as count, energy, and amplitude, are stable and low in the crack generation phase and low-speed crack propagation phase, and relatively unstable and high in the high-speed crack propagation phase and fracture phase. The type of signals is burst emission and the frequency ranges from 100kHz to 180kHz. From these correlations, it may be possible to predict the remaining service life of a pressure vessel from the results of short-term AE monitoring of crack propagation.
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Xie, Jingsong, Wei Cheng, Yanyang Zi, and Mingquan Zhang. "Phase-based spectrum analysis method for identifying weak harmonics." Journal of Vibration and Control 24, no. 23 (2018): 5585–96. http://dx.doi.org/10.1177/1077546318760904.
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Fault characteristic frequency extraction is an important means for the fault diagnosis of rotating machineries. Traditional signal processing methods commonly use the amplitude information of signals to detect damages. However, when the amplitudes of characteristic frequencies are weak, the recognition effects of traditional methods may be unsatisfactory. Therefore, this paper proposes the phase-based enhanced phase waterfall plot (EPWP) method and frequency equal ratio line (FERL) method for identifying weak harmonics. Taking a cracked rotor as an example, the characteristic frequency detection performances of the EPWP and FERL methods are compared with that of the traditional signal processing methods namely fast Fourier transform, short-time Fourier transform, discrete wavelet transform, continuous wavelet transform, ensemble empirical mode decomposition, and Hilbert–Huang transform. Research results demonstrate that the effects of EPWP and FERL for the recognitions of weak harmonics which are contained in steady signals and transient signals are better than that of the traditional signal processing methods. The accurate identification of weak characteristic frequencies in the vibration signals can provide an important reference for damage detections and improve the diagnostic accuracy.
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Akinin, K. P., V. G. Kireyev, I. S. Petukhov, A. A. Filomenko, and E. M. Mihailik. "FREQUENCY CHARACTERISTICS OF BRUSHLESS MAGNETOELECTRIC MOTORS OF RETURN-ROTARY MOTION." Praci elektrodinamiki Nacionalanoi akademii nauk Ukraini Institutu 2020, no. 57 (2020): 73–80. http://dx.doi.org/10.15407/publishing2020.57.073.
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n this paper, the frequency characteristics of a special brushless magnetoelectric motor of return-rotary motion with sinusoidal and rectangular forms of the carrier signal are investigated. The method of generating a feedback signal on the amplitude of the rotor shaft oscillations angle has been improved by fixing the value of the signal at the moment of reaching its amplitude. The method of calculating the control system of the oscillations angle amplitude is investigated based on the frequency characteristics of the open-loop system by setting the phase stability margin. Examples of the calculation of transient processes of regulation of the oscillations angle amplitude and the effective value of the stator current when starting the motor and changing the mechanical load are given. References 9, figures 6, tables 2.
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Nguyen, Anh Hong, Michael Rath, Erik Leitinger, Khang Van Nguyen, and Klaus Witrisal. "Gaussian Process Modeling of Specular Multipath Components." Applied Sciences 10, no. 15 (2020): 5216. http://dx.doi.org/10.3390/app10155216.
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The consideration of ultra-wideband (UWB) and mm-wave signals allows for a channel description decomposed into specular multipath components (SMCs) and dense/diffuse multipath. In this paper, the amplitude and phase of SMCs are studied. Gaussian Process regression (GPR) is used as a tool to analyze and predict the SMC amplitudes and phases based on a measured training data set. In this regard, the dependency of the amplitude (and phase) on the angle-of-arrival/angle-of-departure of a multipath component is analyzed, which accounts for the incident angle and incident position of the signal at a reflecting surface—and thus for the reflection characteristics of the building material—and for the antenna gain patterns. The GPR model describes the similarities between different data points. Based on its model parameters and the training data, the amplitudes of SMCs are predicted at receiver positions that have not been measured in the experiment. The method can be used to predict a UWB channel impulse response at an arbitrary position in the environment.
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Shi, Lei, Shurong Yuan, and Bo Yao. "Unconventionally Designed Tracking Loop Adaptable to Plasma Sheath Channel for Hypersonic Vehicles." Sensors 21, no. 1 (2020): 21. http://dx.doi.org/10.3390/s21010021.
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An aircraft that moves through the atmosphere at hypersonic speed is covered by plasma sheath, which causes random and fast time-varying amplitude attenuation and phase fluctuation in received signals. This paper comprehensively analyzes the mechanism of the amplitude attenuation effects on a traditional phase-locked loop (PLL), which is always ignored in traditional scenarios (such as satellite telemetry and vehicle communication). Simulation results and theoretical analysis showed that traditional PLL does not work reliably for signal carrier tracking with the severe time-varying amplitude attenuation of the plasma sheath channel. In this paper, an unconventionally designed Kalman filter (KF) tracking loop that is aware of phase dynamics and amplitude attenuation fluctuation for hypersonic vehicles is proposed. To introduce time-varying amplitude attenuation into the proposed KF-based tracking loop, the amplitude attenuation is first modeled with an autoregressive model. The statistical characteristics of the amplitude and phase fluctuation are then incorporated into the state equation and observation equation. Simulation results indicate that the proposed tracking loop is stable when the signal-to-noise ratio is −10 dB with the Ka band, even in the most severe flight environment for hypersonic vehicles.
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Yu, Liang Jun, Li Hua Sun, and Cui Cui Huang. "Design of Comprehensive Test Instrument Based on FPGA and Cortex-M0." Applied Mechanics and Materials 312 (February 2013): 583–87. http://dx.doi.org/10.4028/www.scientific.net/amm.312.583.
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The design consists of three modules: the voltage amplitude measurement module, the level oscillator module and the amplitude-frequency characteristic test module. The voltage amplitude measurement module uses AD817 to consist three-stage amplifier. The magnification of each level can be adjusted for 1 times/10 times. At the same time, the author uses the Cortex-M0 for controlling the relay switch to achieve automatic range conversion. The principle of DDS is adopted in the level oscillator module. FPGA is used for realizing the phase accumulator, the phase modulator, the sine ROM look-up table. Digital signal is finally outputted by high-speed analog-to-digital conversion chip DAC900. Then, by controlling the 6-channel relay switch to make the magnification in the amplifying circuit,which can be adjusted step-by-step from-30dB to 20dB. Through outputting sine wave whose amplitude is fixed, but frequency is variable to the network under test, amplitude-frequency characteristic test module measures the relation betthe authoren the amplitude change of the output signal and the signal frequency to obtain the amplitude-frequency characteristics of the network under test..
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Kan, Valery, Michael E. Gorbunov, and Viktoria F. Sofieva. "Fluctuations of radio occultation signals in sounding the Earth's atmosphere." Atmospheric Measurement Techniques 11, no. 2 (2018): 663–80. http://dx.doi.org/10.5194/amt-11-663-2018.
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Abstract. We discuss the relationships that link the observed fluctuation spectra of the amplitude and phase of signals used for the radio occultation sounding of the Earth's atmosphere, with the spectra of atmospheric inhomogeneities. Our analysis employs the approximation of the phase screen and of weak fluctuations. We make our estimates for the following characteristic inhomogeneity types: (1) the isotropic Kolmogorov turbulence and (2) the anisotropic saturated internal gravity waves. We obtain the expressions for the variances of the amplitude and phase fluctuations of radio occultation signals as well as their estimates for the typical parameters of inhomogeneity models. From the GPS/MET observations, we evaluate the spectra of the amplitude and phase fluctuations in the altitude interval from 4 to 25 km in the middle and polar latitudes. As indicated by theoretical and experimental estimates, the main contribution into the radio signal fluctuations comes from the internal gravity waves. The influence of the Kolmogorov turbulence is negligible. We derive simple relationships that link the parameters of internal gravity waves and the statistical characteristics of the radio signal fluctuations. These results may serve as the basis for the global monitoring of the wave activity in the stratosphere and upper troposphere.
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Lysenko, Iu Iu, Yu V. Kuts, V. M. Uchanin, and V. F. Petryk. "Research of oscillation mode in automated pulsed eddy current testing systems." Information extraction and processing 2021, no. 49 (2021): 9–18. http://dx.doi.org/10.15407/vidbir2021.49.009.
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The formation and analysis of eddy current probe signals obtained in pulsed excitation mode is considered. The proposed method of implementing pulsed eddy current testing with the formation of attenuating harmonic oscillations is more resistant to the effects of noise and interference that accompany the process of inspected object parameters evaluation. The equivalent scheme of the system “test object–eddy current probe” is developed and analyzed. The obtained mathematical model of the eddy current probe signals allowed proposing the natural frequency and the attenuation as informative signals parameters, which are determined from signals phase and amplitude characteristics. Developed algorithm and the proposed methodology was implemented for evaluation of eddy current signals parameters and related characteristics of testing objects. This method was experimentally verified on a series of different test specimens. The obtained results confirm the possibility to apply the proposed informative signals to solve some problems concerned with automated eddy current testing. The formation and analysis of eddy current probe signals obtained in pulsed excitation mode are considered. The proposed method of implementing pulsed eddy current testing with the formation of attenuating harmonic oscillations is more resistant to the effects of noise and interference that accompany the process of automated eddy current testing. The equivalent scheme of the system “test object–eddy current probe” is developed and analyzed. The obtained mathematical model of the eddy current probe signals allows proposing the natural frequency and the attenuation as informative signals parameters, which are determined from signal phase and amplitude characteristics. Methods of increasing the accuracy of determining the eddy current probe signals attenuation and frequency using trends of signals phase and amplitude characteristics are considered. The proposed signal processing method was verified by modeling the process of determining the eddy current probe signals attenuation and the frequency from the signal with Gaussian noise. Algorithmic and software were developed based on the simulation results and the proposed improved methodology was implemented for determining signals parameters and related parameters and characteristics of testing objects.
Dissertations / Theses on the topic "Amplitude and phase characteristics of signal"
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Дубицька, Марія Сергіївна, Мария Сергеевна Дубицкая та M. S. Dubyts’ka. "Вдосконалення способу прогнозу диз’юнктивних порушень методом акустичної геолокації при відпрацюванні пологозалягаючих вугільних пластів". Thesis, Видавництво НГУ, 2014. http://ir.nmu.org.ua/handle/123456789/3692.
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У дисертації вирішене актуальне науково-технічне завдання підвищення
ефективності прогнозу мілкоамплітудних геологічних порушень вугільних
пластів методом неруйнівного контролю до 95%.
Запропонована і обґрунтована математична модель розповсюдження
акустичного хвильового пакету в дисперсійному породному середовищі,
заснована на інформаційній амплітудно-фазовій модуляції несучих частот
зондуючого сигналу.
Розроблено ефективний спосіб прогнозу прихованих диз'юнктивів у
вугільних пластах методом неруйнівного контролю. У його основу покладено
аналіз особливостей прояву розривних геологічних порушень у функціях
модуляційних параметрів сигналу, який отримано в результаті акустичного
зондування вуглепородного масиву.
Закономірності, отримані в результаті досліджень використані для розробки
рекомендацій щодо тектонічної будови вугільних пластів для шахт
«Дніпровська», «Краснолиманська» та «Степова».<br>В диссертации решена актуальная научно-техническая задача повышения
эффективности прогноза малоамплитудных геологических нарушений
угольных пластов методом неразрушающего контроля до 95%.
Организованы и проведены комплексные шахтные, лабораторные и
аналитические исследования распространения акустических колебаний в
сложноструктурном породном массиве с геологическими нарушениями при
использовании различных способов генерации зондирующего акустического
сигнала.
Впервые доказан факт информационной амплитудно-фазовой модуляции
низкочастотных огибающих спектральной плотности мощности несущих
частот зондирующего сигнала, прошедшего через исследуемый породный
массив.
Предложена и обоснована математическая модель распространения
акустического волнового пакета в диспергирующей породной среде,
отличающаяся от известных тем, что основана она на информационной
амплитудно-фазовой модуляции несущих частот зондирующего сигнала.
Предложена методика обработки сигнала волнового пакета зондирующего
сигнала, прошедшего сквозь структурно-неоднородный породный массив,
отличающаяся от известных тем, что в ее основу заложена фазовая
демодуляция функции спектральной плотности мощности с применением
метода низкочастотного эквивалента. Методика позволяет определить
геометрические параметры неоднородностей при прохождении выработок в
зонах геологических нарушений.
Установлено, что исследование низкочастотной огибающей спектральной
плотности мощности несущих частот и последующая ее фазовая демодуляция в
среде Matlab позволяет получить фазовые характеристики огибающей, которые
несут в себе информационную составляющую, отвечающую за структуру
угольного пласта. Доказано, что в случае наличия нарушения график фазовой
характеристики имеет один глобальный экстремум, который существенно
отличается от остальных – локальных – своей первой производной. Причем,
при фазовой демодуляции максимальная амплитуда несущей частоты иногда
бывает менее информативна, чем боковые, поэтому в программе оценки
нижних частот расчет функции полной фазы низкочастотных спектральных
составляющих, осуществляется по четырем несущим с максимальной
амплитудой, а среди них выбирается одна – с наиболее резким изменением
сигнала. На основе их анализа сделан вывод о том, что на изгибе функции
отражается излом характеристики.
Доказано, что точка глобального экстремума фазовой характеристики
низкочастотной огибающей спектральной плотности мощности несущих
частот, вычисляемая методом низкочастотного эквивалента, определяет
местонахождение разрывного геологического нарушения в угольном пласте с
надежностью не менее 0.95, что позволяет существенно повысить надежность
прогноза геоакустическим методом.
Описанная точка экстремума возникает в определенное время
распространения искусственного сигнала. Имея данные о местонахождении
источника сигнала в момент времени его прохождения сквозь массив,
местонахождении приемника и скорость распространения акустической волны
в волноводе можно определить координаты соответствующей точки
разрывного нарушения. Основываясь на анализе данного экстремума
установлено, что координаты разрывного нарушения на прямой от источника
искусственно генерируемого сигнала до приемника в плоскости волновода
определяются произведением средней скорости распространения акустического
колебания в угольном пласте и временем, соответствующем возникновению
глобального экстремума фазовой характеристики низкочастотной огибающей
спектральной плотности мощности несущих частот, что позволяет определить
геометрические параметры разрывного нарушения в угольном пласте.
Разработан эффективный способ прогноза скрытых дизьюнктивов в
угольных пластах методом неразрушающего контроля. В его основу положен
анализ особенностей проявления разрывных геологических нарушений в
функциях модуляционных параметров сигнала, который получен в результате
акустического зондирования углепородного массива.
Закономерности, полученные в результате исследований использованы для
разработки рекомендаций относительно тектонического строения угольных
пластов для шахт «Краснолиманская» ГП «УК «Краснолиманская»,
«Днепровская» и «Степная» ПАО «ДТЭК Павлоградуголль».<br>In the thesis, the actual scientific and technical problem of raising efficiency of
low-amplitude geological disturbances forecast in coal layers by the method of nondestructive
testing up to 95 % is solved.
The comprehensive mine, laboratory and analytical research concerning
propagation of acoustic oscillations in the complex structured rock massif with
geological faults by using different methods of probing acoustic signal generation are
organized and conducted.
The mathematical model of spreading acoustic wave packet in the dispersion
medium based on the information and amplitude-phase modulation of carrying
frequencies of the probing signal is proposed and justified.
An effective method of the forecasting hidden disjunctives in coal layers by the
method of non-destructive testing is developed. The method is based on the analysis
of characteristic emergencies of geological faults in the functions of a signal
modulation parameters obtained by acoustic probing of coal-rock massif.
The regularities obtained from the research results are used to develop
recommendations regarding the tectonic structure of coal layers for mines
"Dniprovska", "Krasnolymanska" and "Stepova".
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Barros, M. de P. "Crystal filters having prescribed amplitude and phase characteristics." Thesis, University of Essex, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.374712.
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Senin, Sergei. "Dynamics of amplitude and phase scintillations in a millimetre-wave satellite downlink." Thesis, University of Portsmouth, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.310392.
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Thomas, Edwin Christopher. "Phase and amplitude variations in the wave fields of ionospherically reflected radio waves." Thesis, University of Leicester, 1986. http://hdl.handle.net/2381/35807.
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The wavefronts of high frequency (HF) radio waves received after reflection from the ionosphere exhibit both spatial non-linearities and temporal variations which limit the performance of large aperture receiving arrays. The objective of this investigation was to measure the phase and amplitude of ionospherically propagated signals in order to relate these parameters to the reflection process. This thesis describes the design and construction of a large aperture multi-element array and its implementation for wavefrot investigations. The hardware and software developed to control the equipment and to record the measurements are described. The procedures required to verify the performance of the experimental system are discussed and results are presented which demonstrate the accuracy of the measurements. The array was utilised for studies of signals received from several transmitters situated throughout Western Europe. The results obtained demonstrate the widely different behaviour of signals received over the various propagation paths and these have been related to the modal content of the received signals. Limited periods existed during which a single ionospheric mode was received and data corresponding to this condition have been compared with those which would be expected if the signal consisted of both a specular component and a cone of diffracted rays. This model is unable to explain the experimental results. Numerical models of the received signal were therefore developed. Results of these and comparisons with experimental results suggest that the measured parameters can be explained by the existence of a specular component with a varying direction of arrival (DOA), plus some contribution from random components. The experimental results indicate that the random or diffracted components normally contribute less than 10% of the received power in a single moded signal.
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Лисенко, Юлія Юріївна. "Інформаційно–діагностична система імпульсного вихрострумового неруйнівного контролю виробів машинобудування". Doctoral thesis, Київ, 2017. https://ela.kpi.ua/handle/123456789/21603.
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Дисертація присвячена розробці інформаційно – діагностичної системи імпульсного вихрострумового неруйнівного контролю виробів машинобудування. В роботі проаналізовано процеси в ланцюгах вихрострумового перетворювача в умовах імпульсному режиму збудження та визначено умови виникнення загасаючих гармонічних коливань, що дозволило в якості інформативних параметрів сигналів вихрострумового перетворювача запропонувати використання їх власної частоти та коефіцієнта загасання.
В роботі розроблено методику обробки та аналізу інформативних параметрів сигналів вихрострумового перетворювача в імпульсному режимі збудження, в основі якої лежить визначення запропонованих інформативних параметрів цих сигналів через їх амплітудну та фазову характеристики за допомогою застосування перетворення Гільберта. Запропоновано використання експоненційної апроксимації для амплітудної характеристики та лінійного тренду для фазової характеристики сигналу вихрострумового перетворювача для підвищення точності визначення інформативних параметрів цього сигналу.
Проведено аналіз похибок визначення частоти власних коливань та коефіцієнта загасання сигналу вихрострумового перетворювача, який дозволив визначити умови отримання мінімальної похибки визначення цих інформативних параметрів сигналу та визначити оптимальний час аналізу, що суттєво впливає на результати контролю в умовах впливу завад і шумів.
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Uner, Muhittin. "Frequency, amplitude, and phase tracking of nonsinusoidal signal in noise with extended Kalman filter." Thesis, Monterey, California. Naval Postgraduate School, 1991. http://hdl.handle.net/10945/28235.
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Approved for public release; distribution is unlimited<br>This thesis applies extended Kalman filtering to the problem of estimating frequency, amplitude, and phase of a nonsinusoidal periodic signal contaminated by additive white, Gaussian noise. Parameters will be estimated up to mth significant harmonic component. It also gives an approach for the case of less than mth significant harmonic components. The estimator will track the signal's fundamental frequency, amplitudes, and phases while these parameters are changing slowly over time. The amplitudes are estimated as if the fundamental frequency estimate is correct; the frequency and the phases of the signal are estimated as if the amplitude estimation is correct. This thesis also contains tracking and the capture behavior of the filter.
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Patriksson, Alfred. "Radio signal DOA estimation : Implementing radar signal direction estimation on an FPGA." Thesis, Linköpings universitet, Datorteknik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-157144.
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This master’s thesis covers the design and implementation of a monopulse directionof arrival (DOA) estimation algorithm on an FPGA. The goal is to implement a complete system that is capable of estimating the bearing of an incident signal. In order to determine the estimate quality both a theoretical and practical noise analysis of the signal chain is performed. Special focus is placed on the statistical properties of the transformation from I/Q-demodulated signals with correlated noise to a polar representation. The pros and cons for three different methods of calculating received signal phasors are also covered.The system is limited to two receiving channels which constrains this report to a 2D analysis. In addition the used hardware is limited to C-band signals. We show that an FPGA implementation of monopulse techniques is definitely viable and that an SNR higher than ten dB allows for a gaussian approximation of the polar representationof an I/Q signal.
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Neužil, Jan. "Uživatelské rozhraní pro HP89410A." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2009. http://www.nusl.cz/ntk/nusl-217775.
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The aim of this thesis was to develop user interface in LabVIEW to make typical measurements with spectral analyzer HP89410A There is introduced the theory of operation of an analogue heterodyne and a digital FFT spectral analyzer. It is explained the background of the Fast Fourier Transform. There are discussed the key settings in measuring with FTT analyzer, like window function, bandwidth, number of frequency points, or the averaging. Further is described the program, which was developed for measuring frequency characteristic by white noise and by stepped measurement. It was also made a module for measuring Signal to Noise Ratio and module for Total Harmonic Distortion. In the last part of this thesis are shown the results of processed exemplar measurements.
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Ekanthalingam, Ravikanth. "Amplitude Estimation of Minimum Shift Keying in the presence of Co-channel interference." Ohio University / OhioLINK, 2004. http://www.ohiolink.edu/etd/view.cgi?ohiou1107802525.
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Jabloun, Meryem. "Modélisation de signaux fortement non stationnaires à phase et à amplitude locales polynomiales." Phd thesis, Grenoble INPG, 2007. http://tel.archives-ouvertes.fr/tel-00176079.
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Ce travail de recherche est consacré à l'élaboration et le développement d'une nouvelle méthode d'estimation<br />et de reconstruction de signaux fortement non-stationnaires, modulés non-linéairement à la fois<br />en amplitude et en fréquence. L'estimation de tels signaux dans un contexte trés bruité est un problème<br />délicat et les méthodes existantes de la littérature présentent plusieurs inconvénients dans ce cas.<br />Nous avons montré comment une approche locale permet une meilleure adaptabilité du modèle à la<br />nature des variations locales des amplitudes et des fréquences instantanées. Les résultats de l'estimation<br />sont par conséquent améliorés. L'originalité de la méthode proposée tient à l'application de modèles paramétriques bien adaptés sur des segments temporels de courtes durées extraits du signal étudié. Nous<br />avons proposé une stratégie de segmentation puis une stratégie de fusion des segments estimés permettant<br />la reconstruction du signal dans la totalité de sa durée. L'approche proposée permet de s'affranchir d'un<br />modèle global du signal requérant un ordre d'approximation élevé.<br />La validation de l'efficacité de l'estimation a été effectuée au préalable sur un segment temporel court.<br />Le modèle considéré localement consiste en une approximation polynomiale de la fréquence et de l'amplitude<br />exprimée dans une base polynomiale discrète et orthonormale que nous avons calculée. Cette base<br />permet de réduire le couplage entre les paramètres du modèle. Nous proposons et comparons deux techniques<br />différentes pour estimer ces derniers. La première est fondée sur la maximisation de la fonction<br />de vraisemblance en utilisant la technique d'optimisation stochastique le recuit simulé. Tandis que la<br />deuxième se base sur une approche Bayésienne employant les méthodes MCMC simulées par l'algorithme<br />de Metroplois-Hastings.<br />Nous montrons, sur des simulations et également sur des signaux réels, que l'approche proposée fournit<br />de bons résultats d'estimation par comparaison à celles de la HAF.
Books on the topic "Amplitude and phase characteristics of signal"
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Shirokov, Igor', and Yuriy Gimpilevich. Research of communication channel characteristics. INFRA-M Academic Publishing LLC., 2020. http://dx.doi.org/10.12737/1093426.
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The questions of studying the amplitude and phase characteristics of communication channels of radio engineering systems are considered. As part of the research, a homodyne method for converting microwave signals is proposed, which makes it possible to measure amplitude and phase fluctuations with high accuracy and with the utmost simplicity of measuring equipment. The development of the homodyne method of signal transformation for the purposes and tasks of determining the amplitude and phase fluctuations of signals during the propagation of radio waves on open lines of sight is presented. The features of homodyne signal transformation in the presence of various destabilizing factors are considered. The issues of synchronization of reference generators on different parts of the measuring route are considered. The results of theoretical and experimental studies of amplitude and phase fluctuations on land and sea lines of sight are presented.
 For students and teachers, as well as anyone interested in radio engineering.
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Üner, Muhittin. Frequency, amplitude, and phase tracking of nonsinusoidal signal in noise with extended Kalman filter. Naval Postgraduate School, 1991.
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Phase characteristics and time responses of unknown linear systems determined from measured CW amplitude data. U.S. Dept. of Commerce, Technology Administration, National Institute of Standards and Technology, 1991.
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Linkimer, Lepolt. Earthquake or Explosion - Seismic Signal Identification in Eastern Russian using Amplitude Phase Ratios Obtained From Analog Records. VDM Verlag Dr. Mueller e.K., 2007.
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Ascheid, Gerd, and Heinrich Meyr. Synchronization in Digital Communication Volume I, Phase-, Frequency-Locked Loops, and Amplitude Control (Wiley Series in Telecommunications and Signal Processing). John Wiley & Sons, 1990.
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Sakamoto, Keiko. Signal Intensity Characteristics of Liver Masses at Hepatobiliary Phase Images of Gadoxetate-Enhanced MR (EOB-MR): Qualitative Assessment. INTECH Open Access Publisher, 2012.
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Wendling, Fabrice, Marco Congendo, and Fernando H. Lopes da Silva. EEG Analysis. Edited by Donald L. Schomer and Fernando H. Lopes da Silva. Oxford University Press, 2017. http://dx.doi.org/10.1093/med/9780190228484.003.0044.
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This chapter addresses the analysis and quantification of electroencephalographic (EEG) and magnetoencephalographic (MEG) signals. Topics include characteristics of these signals and practical issues such as sampling, filtering, and artifact rejection. Basic concepts of analysis in time and frequency domains are presented, with attention to non-stationary signals focusing on time-frequency signal decomposition, analytic signal and Hilbert transform, wavelet transform, matching pursuit, blind source separation and independent component analysis, canonical correlation analysis, and empirical model decomposition. The behavior of these methods in denoising EEG signals is illustrated. Concepts of functional and effective connectivity are developed with emphasis on methods to estimate causality and phase and time delays using linear and nonlinear methods. Attention is given to Granger causality and methods inspired by this concept. A concrete example is provided to show how information processing methods can be combined in the detection and classification of transient events in EEG/MEG signals.
Book chapters on the topic "Amplitude and phase characteristics of signal"
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Yu, Jianjun, and Nan Chi. "Carrierless Amplitude and Phase Modulation." In Digital Signal Processing In High-Speed Optical Fiber Communication Principle and Application. Springer Singapore, 2020. http://dx.doi.org/10.1007/978-981-15-3098-2_10.
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Wetsel, G. C., and Z. M. Liu. "Frequency Dependence of Amplitude and Phase of Photothermal-Optical-Beam-Deflection Signal." In Photoacoustic and Photothermal Phenomena II. Springer Berlin Heidelberg, 1990. http://dx.doi.org/10.1007/978-3-540-46972-8_42.
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Lemkhenter, Abdelhak, and Paolo Favaro. "Boosting Generalization in Bio-signal Classification by Learning the Phase-Amplitude Coupling." In Lecture Notes in Computer Science. Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-71278-5_6.
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Wu, Rongrong, He Huang, and Tingwen Huang. "Learning of Phase-Amplitude-Type Complex-Valued Neural Networks with Application to Signal Coherence." In Neural Information Processing. Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-70087-8_10.
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Smyrnaios, M., and S. Schön. "GNSS Antenna Impact on the Resulting Multipath Effects in Carrier-Phase and Signal Amplitude." In International Association of Geodesy Symposia. Springer International Publishing, 2015. http://dx.doi.org/10.1007/1345_2015_169.
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Stark, Hans-Georg. "Identification of Amplitude and Phase Discontinuities in the Intensity Signal of a Nd-YAG solid state laser." In Proceedings of the Third European Conference on Mathematics in Industry. Springer Netherlands, 1990. http://dx.doi.org/10.1007/978-94-009-0629-7_55.
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Hong, Wenpeng, Yunlong Zhou, and Dong Deng. "PSD Characteristics of Air-water Two-Phase Cross Flow Based on Pressure-difference Fluctuation Signal." In Challenges of Power Engineering and Environment. Springer Berlin Heidelberg, 2007. http://dx.doi.org/10.1007/978-3-540-76694-0_176.
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Wang, Xu, Huiyong Li, and Julan Xie. "The Impact Analysis of the Array Elements Number on the Beam Direction in the Presence of Amplitude and Phase Errors." In The Proceedings of the Second International Conference on Communications, Signal Processing, and Systems. Springer International Publishing, 2013. http://dx.doi.org/10.1007/978-3-319-00536-2_60.
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Slowik, Adam. "Hybridization of Evolutionary Algorithm with Yule Walker Method to Design Minimal Phase Digital Filters with Arbitrary Amplitude Characteristics." In Lecture Notes in Computer Science. Springer Berlin Heidelberg, 2011. http://dx.doi.org/10.1007/978-3-642-21219-2_10.
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Schmal, Christoph, Gregor Mönke, and Adrián E. Granada. "Analysis of Complex Circadian Time Series Data Using Wavelets." In Methods in Molecular Biology. Springer US, 2022. http://dx.doi.org/10.1007/978-1-0716-2249-0_3.
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AbstractExperiments that compare rhythmic properties across different genetic alterations and entrainment conditions underlie some of the most important breakthroughs in circadian biology. A robust estimation of the rhythmic properties of the circadian signals goes hand in hand with these discoveries. Widely applied traditional signal analysis methods such as fitting cosine functions or Fourier transformations rely on the assumption that oscillation periods do not change over time. However, novel high-resolution recording techniques have shown that, most commonly, circadian signals exhibit time-dependent changes of periods and amplitudes which cannot be captured with the traditional approaches. In this chapter we introduce a method to determine time-dependent properties of oscillatory signals, using the novel open-source Python-based Biological Oscillations Analysis Toolkit (pyBOAT). We show with examples how to detect rhythms, compute and interpret high-resolution time-dependent spectral results, analyze the main oscillatory component, and to subsequently determine these main components’ time-dependent instantaneous period, amplitude, and phase. We introduce step-by-step how such an analysis can be done by means of the easy-to-use point-and-click graphical user interface (GUI) provided by pyBOAT or executed within a Python programming environment. Concepts are explained using simulated signals as well as experimentally obtained time series.
Conference papers on the topic "Amplitude and phase characteristics of signal"
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Zubov, V. A. "Modulation spectral method to measure amplitude-phase characteristics of optical signals and transfer functions varying in time." In Seventh International Symposium on Laser Metrology Applied to Science, Industry, and Everyday Life, edited by Yuri V. Chugui, Sergei N. Bagayev, Albert Weckenmann, and P. Herbert Osanna. SPIE, 2002. http://dx.doi.org/10.1117/12.484569.
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Stanley, K. N., and D. E. Nikitopoulos. "Phase Discrimination Techniques for Phase Doppler Measurements in Dispersed, Bubbly Flows." In ASME 1997 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 1997. http://dx.doi.org/10.1115/imece1997-0792.
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Abstract A combined Phase-Doppler Anemometry (PDA) and video imaging measurement technique for non-intrusive measurements in dispersed bubbly flows is presented. A one-component Phase-Doppler Velocimetry system has been employed to measure liquid seeding particle size and velocity as well as bubble size and velocity non-intrusively. Measurable flow quantities include: (1) mean velocities and RMS velocity fluctuations for bubbles and liquid; (2) local bubble diameter, and (3) local bubble passage frequency. Non-intrusive local measurement of seeding particle and bubble size is an advantage over techniques used previously (Laser-Doppler Velocimetry, Hot-Film Anemometry). Visual data collected simultaneously with the light-scattering measurements and analyzed with the aid of image processing are used to verify the trends portrayed by the light-scattering measurements. A multi-level phase discrimination technique based on velocity, diameter, and relative data rates between the carrier and dispersed phases is employed to minimize bias from bubble signals when measuring liquid phase data in dilute flows. An amplitude discrimination technique for the Phase-Doppler system is proposed for higher volume fraction flows. The proposed method enables local non-intrusive measurement of liquid phase velocity as well as local bubble size characteristics, velocity, and concentration.
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Jeng, Jang-Der, Yuan Kang, Yeon-Pun Chang, and Shyh-Shyong Shyr. "Characteristics in Response Integration and Bifurcation of a Forced Duffing Oscillator." In ASME Turbo Expo 2007: Power for Land, Sea, and Air. ASMEDC, 2007. http://dx.doi.org/10.1115/gt2007-28118.
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The Duffing oscillator is well-known models of nonlinear system, with applications in many fields of applied sciences and engineering. In this paper, a response integration algorithm is proposed to analyze high-order harmonic and chaotic motions in this oscillator for modeling rotor excitations. This method numerically integrates the distance between state trajectory and the origin in the phase plane during a specific period and predicted intervals with excitation periods. It provides a quantitative characterization of system responses and can replace the role of the traditional stroboscopic technique (Poincare´ section method) to observe bifurcations and chaos of the nonlinear oscillators. Due to the signal response contamination of system, thus it is difficult to identify the high-order responses of the subharmonic motion because of the sampling points on Poincare´ map too near each other. Even the system responses will be made misjudgments. Combining the capability of precisely identifying period and constructing bifurcation diagrams, the advantages of the proposed response integration method are shown by case studies. Applying this method, the effects of the change in the stiffness and the damping coefficients on the vibration features of a Duffing oscillator are investigated in this paper. From simulation results, it is concluded that the stiffness and damping of the system can effectively suppress chaotic vibration and reduce vibration amplitude.
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Lee, Yong Ho, Soon Heung Chang, and Won-Pil Baek. "Vibration Characteristics of a Vertical Round Tube According to Heat Transfer Regimes." In 10th International Conference on Nuclear Engineering. ASMEDC, 2002. http://dx.doi.org/10.1115/icone10-22161.
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This paper presents the results of an experimental work on the effects of boiling heat transfer regimes on the flow-induced vibration (FIV). The experiment has been performed using an electrically heated vertical round tube through which water flows at atmospheric pressure. Vibration characteristics of the heated tube are changed significantly by heat transfer regimes and flow patterns. For single-phase liquid convection, the rod vibrations are negligible. However, on the beginning of subcooled nucleate boiling at tube exit, vibration level becomes very large. As bubble departure occurs at the nucleation site of heated surface, the vibration decreases to saturated boiling region where thermal equilibrium quality becomes 0.0 at tube exit. In saturated boiling region, vibration amplitude increases with exit quality up to a certain maximum value due to the reinforced turbulence then decreases. At liquid film dryout condition, vibration could be regarded as negligible, however, these results cannot be extended to DNB-type CHF mechanism. Frequency analysis results of vibration signals suggested that excitation sources be different with heat transfer regimes. This study would contribute to improve the understanding of the relationship between boiling heat transfer and FIV.
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Provenza, Andrew J., and Carlos R. Morrison. "Control of Fan Blade Vibrations Using Piezoelectrics and Bi-Directional Telemetry." In ASME 2011 Turbo Expo: Turbine Technical Conference and Exposition. ASMEDC, 2011. http://dx.doi.org/10.1115/gt2011-46714.
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A novel wireless device which transfers supply power through induction to rotating operational amplifiers and transmits low voltage AC signals to and from a rotating body by way of radio telemetry has been successfully demonstrated in the NASA Glenn Research Center (GRC) Dynamic Spin Test Facility. In the demonstration described herein, a rotating operational amplifier provides controllable AC power to a piezoelectric patch epoxied to the surface of a rotating Ti plate. The amplitude and phase of the sinusoidal voltage command signal, transmitted wirelessly to the amplifier, was tuned to completely suppress the 3rd bending resonant vibration of the plate. The plate’s 3rd bending resonance was excited using rotating magnetic bearing excitation while it spun at slow speed in a vacuum chamber. A second patch on the opposite side of the plate was used as a sensor. This paper discusses the characteristics of this novel device, the details of a spin test, results from a preliminary demonstration, and future plans.
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Azartash, Kaveh, and Enrico Gratton. "Measuring the Cell-Induced Deformation of Collagen Matrix Detected With Digital Holographic Microscopy." In ASME 2007 2nd Frontiers in Biomedical Devices Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/biomed2007-38064.
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A modified Mach-Zender set-up in reflection is applied to record and reconstruct holographic amplitude and phase images. A charged couple device (CCD) is used to record a hologram and numerical reconstruction algorithms are then applied to rebuild the hologram for obtaining both phase and amplitude information. One could also focus on multiple focal planes from a single hologram, similar to the focusing control of a conventional microscope. The morphology and behavior of mammalian cells is determined by an interaction between signals from the intracellular matrix and the cellular responses. It is important to note that the physical aspect of the extracellular matrix is as significant as the chemical nature of it. Specifically the stresses, mechanical forces, and the profile of the external environment have major effects on cell behavior. The mechanical and physical characteristics of a tissue are greatly dependent on a hierarchical spatial arrangement of its extra-cellular matrix components. A key player in the ECM is collagen which exhibits significant tensile strength on the cellular scale. Digital holographic microscopy (DHM) is applied to study the deformation of collage matrix in response to cell migration.
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Zotov, A. M., P. V. Korolenko, R. T. Kubanov, and N. N. Pavlov. "Amplitude-phase characteristics of vortex diffractals." In Акустооптические и радиолокационные методы измерений и обработки информации. Научно-технологический центр уникального приборостроения РАН, 2021. http://dx.doi.org/10.25210/armimp-2021-10.
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Lee, C. Y., and R. S. Cant. "CFD Investigation of Turbulent Premixed Flame Response to Transverse Forcing." In ASME Turbo Expo 2013: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/gt2013-94312.
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Screech is a high frequency oscillation that is usually characterized by instabilities caused by large-scale coherent flow structures in the wake of bluff-body flameholders and shear layers. Such oscillations can lead to changes in flame surface area which can cause the flame to burn unsteadily, but also couple with the acoustic modes and inherent fluid-mechanical instabilities that are present in the system. In this study, the flame response to hydrodynamic oscillations is analyzed in a controlled manner using high-fidelity Computational Fluid Dynamics (CFD) with an unsteady Reynolds-averaged Navier-Stokes approach. The response of a premixed flame with and without transverse velocity forcing is analyzed. When unforced, the flame is shown to exhibit a self-excitation that is attributed to the anti-symmetric shedding of vortices in the wake of the flameholder. The flame is also forced using two different kinds of low-amplitude out-of-phase inlet velocity forcing signals. The first forcing method is harmonic forcing with a single characteristic frequency, while the second forcing method involves a broadband forcing signal with frequencies in the range of 500–1000 Hz. For the harmonic forcing method, the flame is perturbed only lightly about its mean position and exhibits a limit cycle oscillation that is characteristic of the forcing frequency. For the broadband forcing method, larger changes in the flame surface area and detachment of the flame sheet can be seen. Transition to a complicated trajectory in the phase space is observed. When analyzed systematically with system identification methods, the CFD results, expressed in the form of the Flame Transfer Function (FTF) are capable of elucidating the flame response to the imposed perturbation. The FTF also serves to identify, both spatially and temporally, regions where the flame responds linearly and nonlinearly. Locking-in between the flame’s natural self-excited frequency and the subharmonic frequencies of the broadband forcing signal is found to alter the dynamical behaviour of the flame.
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Haecker, Annika-verena, Gabriel N. Carryon, James L. Tangorra, and Thomas Sattel. "Neural-Based Control of Compliant Foils With Spanwise Flexibility." In ASME 2019 Dynamic Systems and Control Conference. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/dscc2019-9045.
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Abstract The ability to change the spatial distribution of a compliant foil’s flexural rigidity can enhance the foil’s swimming performance capabilities but pose challenges to neural-based control of these types of foils. The same property that makes these foil’s effective propulsors also makes them challenging to control with a neural oscillator, namely the variation in the mechanical properties will cause the amplitude and phase of the sensory feedback signal to vary depending upon the placement of the sensor. In this study we investigate the effect of sensor placement on the entrainment characteristics of a coupled-system consisting of a neural oscillator driving a series of compliant foils with spanwise flexibility (i.e. spatially varying mechanical properties in the dorsal-ventral direction). We find that acquiring sensory feedback from the foil’s stiff region produces a broader range of frequencies over which entrainment occurs compared to acquiring feedback from the compliant region of a foil. Additionally, we characterize the thrust and lift forces generated by spanwise foils as a function of the foil’s flapping frequency and flexural rigidity.
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Kuzmin, Ilya A., Zhanna V. Merkulova, Dmitry V. Prikhodko, and Pavel Y. Vatskov. "Methods of APAA phase-amplitude characteristics measurements automation." In 2017 IEEE Conference of Russian Young Researchers in Electrical and Electronic Engineering (EIConRus). IEEE, 2017. http://dx.doi.org/10.1109/eiconrus.2017.7910788.
Full textReports on the topic "Amplitude and phase characteristics of signal"
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Ma, Mark T. Phase characteristics and time responses of unknown linear systems determined from measured CW amplitude data. National Bureau of Standards, 1991. http://dx.doi.org/10.6028/nist.tn.1349.
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Smith, Jijo K., Howell Li, and Darcy M. Bullock. Populating SAE J2735 Message Confidence Values for Traffic Signal Transitions Along a Signalized Corridor. Purdue University, 2019. http://dx.doi.org/10.5703/1288284317322.
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The communication between connected vehicles and traffic signal controllers is defined in SAE Surface Vehicle Standard J2735. SAE J2735 defines traffic signal status messages and a series of 16 confidence levels for traffic signal transitions. This paper discusses a statistical method for tabulating traffic signal data by phase and time of day and populating the SAE J2735 messages. Graphical representation of the red-green and green-yellow transitions are presented from six intersections along a 4-mile corridor for five different time of day timing plans. The case study provided illustrates the importance of characterizing the stochastic variation of traffic signals to understand locations, phases, and time of day when traffic indications operate with high predictability, and periods when there are large variations in traffic signal change times. Specific cases, such as low vehicle demand and occasional actuation of pedestrian phases are highlighted as situations that may reduce the predictability of traffic signal change intervals. The results from this study also opens up discussion among transportation professionals on the importance of consistent tabulation of confidence values for both beginning and end of green signal states. We believe this paper will initiate dialog on how to consistently tabulate important data elements transmitted in SAE J2735 and perhaps refine those definitions. The paper concludes by highlighting the importance of traffic engineers and connected vehicle developers to work together to develop shared visions on traffic signal change characteristics so that the in-vehicle use cases and human-machine interface (HMI) meet user expectations.
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Singhvi, Punit, Javier García Mainieri, Hasan Ozer, and Brajendra Sharma. Rheology-Chemical Based Procedure to Evaluate Additives/Modifiers Used in Asphalt Binders for Performance Enhancements: Phase 2. Illinois Center for Transportation, 2021. http://dx.doi.org/10.36501/0197-9191/21-020.
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The increased use of softer binders in Illinois over the past decade is primarily attributed to the increased use of recycled materials in asphalt pavement construction. The shift in demand of using PG 58-28 over PG 64-22 has resulted in potential alternative methods to produce softer binders more economically using proprietary products. However, there are challenges in using these proprietary products for asphalt modification because of uncertainty in their long-term performance and significant variability in binder chemistry. The current SuperPave performance grading specification for asphalt binders is insufficient in differentiating binders produced from these modifiers. Therefore, the objective of this study is to evaluate the performance of various softener-type asphalt binder modifiers using a wide array of rheological and chemistry tests for their integration into the Illinois Department of Transportation’s material specifications. The small-strain rheological tests and their parameters allowed for consistent grouping of modified binders and can be used as surrogates to identify performing and nonperforming asphalt binders. A new parameter, Δ|G*|peak τ, was developed from the linear amplitude sweep test and showed potential to discriminate binders based on their large-strain behavior. Chemistry-based parameters were shown to track aging and formulation changes. The modifier sources were identified using fingerprint testing and were manifested in the modified binder chemical and compositional characteristics. The two sources of base binders blended with the modifiers governed the aging rate of the modified binders. Mixture performance testing using the Illinois Flexibility Index Test and the Hamburg Wheel-Track Test were consistent with the rheological and chemical findings, except for the glycol amine-based modified binder, which showed the worst cracking performance with the lowest flexibility index among the studied modifiers. This was contrary to its superior rheological performance, which may be attributed to lower thermal stability, resulting in high mass loss during mixing. According to the characterization of field-aged binders, laboratory aging of two pressurized aging vessel cycles or more may represent realistic field aging of 10 to 15 years at the pavement surface and is able to distinguish modified binders. Therefore, an extended aging method of two pressurized aging vessel cycles was recommended for modified binders. Two different testing suites were recommended for product approval protocol with preliminary thresholds for acceptable performance validated with field-aged data.
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Soloviev, Vladimir, Oleksandr Serdiuk, Serhiy Semerikov, and Arnold Kiv. Recurrence plot-based analysis of financial-economic crashes. [б. в.], 2020. http://dx.doi.org/10.31812/123456789/4121.
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The article considers the possibility of analyzing the dynamics of changes in the characteristics of time series obtained on the basis of recurrence plots. The possibility of using the studied indicators to determine the presence of critical phenomena in economic systems is considered. Based on the analysis of economic time series of different nature, the suitability of the studied characteristics for the identification of critical phenomena is assessed. The description of recurrence diagrams and characteristics of time series that can be obtained on their basis is given. An analysis of seven characteristics of time series, including the coefficient of self-similarity, the coefficient of predictability, entropy, laminarity, is carried out. For the entropy characteristic, several options for its calculation are considered, each of which allows the one to get its own information about the state of the economic system. The possibility of using the studied characteristics as precursors of critical phenomena in economic systems is analyzed. We have demonstrated that the entropy analysis of financial time series in phase space reveals the characteristic recurrent properties of complex systems. The recurrence entropy methodology has several advantages compared to the traditional recurrence entropy defined in the literature, namely, the correct evaluation of the chaoticity level of the signal, the weak dependence on parameters. The characteristics were studied on the basis of daily values of the Dow Jones index for the period from 1990 to 2019 and daily values of oil prices for the period from 1987 to 2019. The behavior of recurrence entropy during critical phenomena in the stock markets of the USA, Germany and France was studied separately. As a result of the study, it was determined that delay time measure, determinism and laminarity can be used as indicators of critical phenomena. It turned out that recurrence entropy, unlike other entropy indicators of complexity, is an indicator and an early precursor of crisis phenomena. The ways of further research are outlined.
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Meidan, Rina, and Robert Milvae. Regulation of Bovine Corpus Luteum Function. United States Department of Agriculture, 1995. http://dx.doi.org/10.32747/1995.7604935.bard.
Full textAbstract:
The main goal of this research plan was to elucidate regulatory mechanisms controlling the development, function of the bovine corpus luteum (CL). The CL contains two different sterodigenic cell types and therefore it was necessary to obtain pure cell population. A system was developed in which granulosa and theca interna cells, isolated from a preovulatory follicle, acquired characteristics typical of large (LL) and small (SL) luteal cells, respectively, as judged by several biochemical and morphological criteria. Experiments were conducted to determine the effects of granulosa cells removal on subsequent CL function, the results obtained support the concept that granulosa cells make a substaintial contribution to the output of progesterone by the cyclic CL but may have a limited role in determining the functional lifespan of the CL. This experimental model was also used to better understand the contribution of follicular granulosa cells to subsequent luteal SCC mRNA expression. The mitochondrial cytochrome side-chain cleavage enzyme (SCC), which converts cholesterol to pregnenolone, is the first and rate-limiting enzyme of the steroidogenic pathway. Experiments were conducted to characterize the gene expression of P450scc in bovine CL. Levels of P450scc mRNA were higher during mid-luteal phase than in either the early or late luteal phases. PGF 2a injection decreased luteal P450scc mRNA in a time-dependent manner; levels were significantly reduced by 2h after treatment. CLs obtained from heifers on day 8 of the estrous cycle which had granulosa cells removed had a 45% reduction in the levels of mRNA for SCC enzymes as well as a 78% reduction in the numbers of LL cells. To characterize SCC expression in each steroidogenic cell type we utilized pure cell populations. Upon luteinization, LL expressed 2-3 fold higher amounts of both SCC enzymes mRNAs than SL. Moreover, eight days after stimulant removal, LL retained their P4 production capacity, expressed P450scc mRNA and contained this protein. In our attempts to establish the in vitro luteinization model, we had to select the prevulatory and pre-gonadotropin surge follicles. The ratio of estradiol:P4 which is often used was unreliable since P4 levels are high in atretic follicles and also in preovulatory post-gonadotropin follicles. We have therefore examined whether oxytocin (OT) levels in follicular fluids could enhance our ability to correctly and easily define follicular status. Based on E2 and OT concentrations in follicular fluids we could more accurately identify follicles that are preovulatory and post gonadotropin surge. Next we studied OT biosynthesis in granulosa cells, cells which were incubated with forskolin contained stores of the precursor indicating that forskolin (which mimics gonadotropin action) is an effective stimulator of OT biosynthesis and release. While studying in vitro luteinization, we noticed that IGF-I induced effects were not identical to those induced by insulin despite the fact that megadoses of insulin were used. This was the first indication that the cells may secrete IGF binding protein(s) which regonize IGFs and not insulin. In a detailed study involving several techniques, we characterized the species of IGF binding proteins secreted by luteal cells. The effects of exogenous polyunsaturated fatty acids and arachidonic acid on the production of P4 and prostanoids by dispersed bovine luteal cells was examined. The addition of eicosapentaenoic acid and arachidonic acid resulted in a dose-dependent reduction in basal and LH-stimulated biosynthesis of P4 and PGI2 and an increase in production of PGF 2a and 5-HETE production. Indomethacin, an inhibitor of arachidonic acid metabolism via the production of 5-HETE was unaffected. Results of these experiments suggest that the inhibitory effect of arachidonic acid on the biosynthesis of luteal P4 is due to either a direct action of arachidonic acid, or its conversion to 5-HETE via the lipoxgenase pathway of metabolism. The detailed and important information gained by the two labs elucidated the mode of action of factors crucially important to the function of the bovine CL. The data indicate that follicular granulosa cells make a major contribution to numbers of large luteal cells, OT and basal P4 production, as well as the content of cytochrome P450 scc. Granulosa-derived large luteal cells have distinct features: when luteinized, the cell no longer possesses LH receptors, its cAMP response is diminished yet P4 synthesis is sustained. This may imply that maintenance of P4 (even in the absence of a Luteotropic signal) during critical periods such as pregnancy recognition, is dependent on the proper luteinization and function of the large luteal cell.