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1
Abramov, Y., V. Kryvtsova, and A. Mikhailyuk. "DETERMINATION OF THE RELIABILITY OF THE GAS GENERATOR OF THE STORAGE SYSTEM AND HYDROGEN SUPPLY." Municipal economy of cities 3, no. 177 (2023): 142–46. http://dx.doi.org/10.33042/2522-1809-2023-3-177-142-146.
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It is noted that as a generalized characteristic of the functional gas generator, which is sensitive to variations in its parameters, it is advisable to use the transfer function, or its analogue - the amplitude-phase frequency characteristic of the gas generator. The amplitude-phase frequency characteristic of the gas generator includes two components - amplitude-frequency and phase-frequency characteristics. During the operation of the gas generator, there will be variations in its parameters - transmission coefficient and time constants, due to aging processes and the influence of external factors. Variations in the parameters of the gas generator lead to variations in its amplitude-frequency and phase-frequency characteristics. Mathematical models for variations in the frequency characteristics of the gas generator are built and it is shown that their frequency range should be limited by the bandwidth of the gas generator. The upper limit of the bandwidth of the gas generator is determined by the root of the biquadratic algebraic equation. For the typical parameters of the gas generator using a hydroreactive sample based on sodium aluminate, graphical dependences of variations of its amplitude-frequency and phase-frequency characteristics are constructed depending on variations of the transmission coefficient, time constants, and frequency. These dependencies are used to determine the parameters of the normal distribution law of variations in the frequency characteristics of the gas generator. In accordance with Lyapunov's rule, a normative law for the distribution of variations in the frequency characteristics of the gas generator is adopted. Due to the symmetry of the distribution of variations in the amplitude-frequency and phase-frequency characteristics of the gas generator, their mathematical expectations are equal to zero. Obtaining estimates of the amplitude and phase reliability of the gas generator is carried out using the Laplace function. The argument of this function is the permissible values of the frequency characteristics of the gas generator and their root mean square deviations. It is shown that with probabilities of 0,9973 and 0,9812, the amplitude-frequency and phase-frequency characteristics of the gas generator will not differ more than when it is turned on. Keywords: gas generator, reliability, frequency characteristics.
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Peng, Pai, Hui Du, Gang Wei, et al. "Experimental Investigation on the Vertical Structure Characteristics of Internal Solitary Waves." Journal of Marine Science and Engineering 10, no. 8 (2022): 1045. http://dx.doi.org/10.3390/jmse10081045.
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An experimental investigation of the vertical structure characteristics of internal solitary waves (ISWs) was systematically carried out in a large gravitationally stratified fluid flume. Four different stratifications were established, and basic elements of ISWs were measured by a conductivity probe array. The vertical distributions of the amplitude, characteristic frequency and waveform of two types of ISWs under different stratifications were obtained, and the experimental results were compared with the theoretical model. The study shows that most vertical structures of the amplitude under different stratifications agree with those of the theoretical model, while there are some deviations for ISWs with large amplitudes. Neither the two-layer model nor the continuously stratified model can effectively describe the variation in the characteristic frequency at different depths with amplitude. For a single small-amplitude ISW, the characteristic frequency first increases and then decreases with increasing depth. The characteristic frequency is largest at the depth of the maximum buoyancy frequency. For an ISW with a relatively large amplitude, there is likely to be a local minimum of the characteristic frequency near the depth where the maximum buoyancy frequency lies. In different stratifications, the sech2 function of KdV theory can describe the waveforms of ISWs at different depths well.
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Violeta, Alexandrova, and Spiridonova Pavlina. "AMPLITUDE AND FREQUENCY MODULATION – A CHARACTERISTIC OF CANINE SOUNDGRAMS." TRADITION AND MODERNITY IN VETERINARY MEDICINE 6, no. 2 (2021): 15–20. https://doi.org/10.5281/zenodo.5733958.
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Zhang, Rongrong, and A. Bazhanov. "Energy Circuit of 1.3 MW with Brayton Cycle." Bulletin of Science and Practice 10, no. 6 (2024): 422–32. http://dx.doi.org/10.33619/2414-2948/103/44.
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In this paper, a constructive scheme of the experimental device is proposed, and the principle of its operation is described in detail. The power circuit of the device has been drawn up. Complex impedance, frequency function, amplitude frequency characteristic and phase-frequency characteristic are obtained by mathematical transformation of the power circuit. The frequency response of the circuit is constructed. As a result of the calculations, we will obtain the amplitude frequency response and the phase frequency response. Using the found values of the characteristics, we will build graphs and draw conclusions about how the characteristics depend on the change in parameters and why the graph lines of the graphs are exactly the way they are.
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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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Klaerner, Matthias, Mario Wuehrl, Lothar Kroll, and Steffen Marburg. "Characteristic amplitude-frequency functions of the radiated sound power." Journal of the Acoustical Society of America 141, no. 5 (2017): 4034. http://dx.doi.org/10.1121/1.4989301.
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Sytnikov, T. V. "INCREASING Q-FACTOR OF THE DIGITAL SENSOR SIGNALS PROCESSING PATH IN AUTONOMOUS MOBILE ROBOTIC PLATFORMS WITH LIMITED COMPUTING RESOURCES." ELECTRICAL AND COMPUTER SYSTEMS, no. 39(115) (2024): 26–34. http://dx.doi.org/10.15276/eltecs.39.115.2024.3.
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Abstract. The paper is considered the problem of constructing autonomous mobile robotic platform with the possibility of rearranging their characteristics depending on the operating conditions. A new approach is proposed for calculating the parameters of a new connection with a series connection of low-order components of the same type. The resulting ratio allows you to accurately calculate the frequencies of the n-th connection of the same type components. Such a connection allows increasing the quality factor characteristic of the amplitude frequency characteristic and reducing the bandwidth by 3 times with eight connected filters of the same type. Bandpass filters and notch Butterworth filters are considered. Behavior of the AFC for serial connection is described. Key words: amplitude frequency characteristic, phase frequency characteristic, Industry 4.0-6.0, digital filter, bandpass filter, notch filter, quality factor characteristics, frequency dependent component, notch filter based on bandpass filer, serial connection.
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Паровик, Р. И. "Анализ добротности вынужденных колебаний дробного линейного осциллятора". Журнал технической физики 90, № 7 (2020): 1059. http://dx.doi.org/10.21883/jtf.2020.07.49436.233-19.
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Using the harmonic balance method, analytical formulas are obtained for calculating the amplitude-frequency and phase-frequency characteristics, as well as the quality factor of the forced oscillations of a linear fractional oscillator. It was established that the characteristics under study depend on the dissipative properties of the medium - memory effects, which are described by derivatives of fractional orders. It is shown that fractional orders affect the attenuation of the oscillatory process and are associated with its quality factor. The calculated curves of the characteristics of the forced oscillations of a linear linear fractional oscillator showed that fractional orders can be considered as control parameters of the oscillatory process in a dissipative medium. Key words: quality factor, amplitude-frequency characteristic, phase-frequency characteristic, fractional derivatives, memory.
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Abramov, Y., V. Kryvtsova, and A. Mikhailyuk. "JUSTIFICATION OF THE METHOD OF DETERMINATION OF THE CONSTANT TIME OF THE GAS GENERATOR OF THE SYSTEM OF STORAGE AND SUPPLY OF HYDROGEN." Municipal economy of cities 3, no. 163 (2021): 216–20. http://dx.doi.org/10.33042/2522-1809-2021-3-163-216-220.
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The method of determining the dynamic parameter - the time constant of the gas generator of the storage and supply of hydrogen on the basis of the hydro-reactive composition is substantiated. The method is based on the use of the amplitude-frequency characteristics of the gas generator of the storage and supply system of hydrogen. The method involves the implementation of three stages. At the first stage, the mathematical dependence of the gas generator time constant on its static parameter and amplitude-frequency characteristic at a fixed frequency is obtained. In the second stage, the choice of this fixed frequency is justified. This dependence includes the value of the amplitude-frequency characteristic of the gas generator of the storage and supply of hydrogen at a fixed frequency, the static parameter of such a gas generator – its transmission coefficient, and the value of the fixed frequency. In the second stage, the choice of this fixed frequency is justified. This choice is made provided that the minimum error in determining the time constant of the gas generator. To determine the static parameter of the gas generator and the value of its amplitude-frequency characteristic at a fixed frequency, an array of data is used, which is formed by measuring the values of the transient function of the gas generator through equal moments of time. These time intervals are chosen according to the Kotelnikov-Nyquist-Shannon theorem. The amplitude-frequency characteristic of the gas generator of the hydrogen storage and supply system is determined numerically. According to the research results, an iterative procedure for determining the time constant of the gas generator of the hydrogen storage and supply system is given. Recommendations for using this procedure are given. The choice of the time constant of the gas generator of the hydrogen storage and supply system is made using the tolerance criterion.
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Liu, Hai Jiang, and Hong Yan Wang. "Development of the Amplitude-Frequency Characteristic Tester Based on SCM Control." Advanced Materials Research 706-708 (June 2013): 776–80. http://dx.doi.org/10.4028/www.scientific.net/amr.706-708.776.
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In this paper, the development of the amplitude-frequency characteristic tester based on SCM control has been introduced. The digital frequency synthesizer has been adopted to generate the automatic sweep frequency sine signals so as to provide the reliable sources for the frequency characteristic tester. The amplitude and the frequency characteristics of the active network and the passive network can be obtained through changing the output signals of circuit measuring network by digital analogy as well as the operation program of the microcontroller under the input signals with different frequencies. In this paper, the working principles of tester, the software and hardware design for the frequency synthesizer signals, the hardware and software design of the data collection channels and the applications of LCD technology have been specially discussed.
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Xu, Lu, Hongsheng Li, Jia Liu, Yunfang Ni, and Libin Huang. "Research on Nonlinear Dynamics of Drive Mode inZ-Axis Silicon Microgyroscope." Journal of Sensors 2014 (2014): 1–11. http://dx.doi.org/10.1155/2014/801618.
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A novel drive method is proposed to increase the vibration amplitude of drive mode of silicon vibratory gyroscopes based on the nonlinear dynamics research made in this paper. A nonlinear dynamic equation, considering the nonlinear mechanical-elastic and electrostatic force, was firstly deduced according to the simplified structure schematic of drive mode. Then, experiments were made to characterize the nonlinear amplitude-frequency response characteristic as well as its dependence on drive voltage. Besides, by solving the nondimensional nonlinear dynamics using Matlab and Simulink, the influence of initial status of drive mode, that is, the displacement and the velocity, on the stable vibration amplitude was presented. The amplitude-frequency characteristic was also analyzed by simulation. The result of simulation shows good agreement with that of experiments. When nonlinearity is present in the amplitude-frequency characteristic, there is a wide flat region with larger amplitude than the peak amplitude obtained in the linear characteristic. Finally, a novel drive method was presented to excite the nonlinear vibration of large amplitude in the downwards-sweeping characteristic curve. It is numerically proved that this merit can be utilized to enlarge the drive mode’s vibration amplitude so as to enhance silicon gyroscopes’ performance.
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Zhou, M., and D. Kuznetsov. "The Energy Circuit of the Exhaust Gas Heat Recovery Circuit of a 25 kW Diesel Generator." Bulletin of Science and Practice 10, no. 6 (2024): 317–29. http://dx.doi.org/10.33619/2414-2948/103/35.
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The purpose of the work is to describe the installation using differential equations and obtain approximate values before the experiment. In this paper, a constructive scheme of the experimental device is proposed, and the principle of its operation is described in detail. The power circuit of the device has been drawn up. Complex impedance, frequency function, amplitude-frequency characteristic and phase-frequency characteristic are obtained by mathematical transformation of the power circuit. The frequency response of the circuit is constructed. As a result of the calculations, we will obtain the amplitude frequency response and the phase frequency response. Using the found values of the characteristics, we will build graphs and draw conclusions about how the characteristics depend on the change in parameters and why the graph lines of the graphs are exactly the way they are.
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Han, Wang, and S. Maltsev. "Energy Circuit of a Thermal Circuit with a Direct-acting Regulator with a Capacity of 1 MW in Pulsating Mode." Bulletin of Science and Practice 10, no. 6 (2024): 372–83. http://dx.doi.org/10.33619/2414-2948/103/40.
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The purpose of the work is to describe the installation using differential equations and obtain approximate values before the experiment. In this paper, a constructive scheme of the experimental device is proposed, and the principle of its operation is described in detail. The power circuit of the device has been drawn up. Complex impedance, frequency function, amplitude-frequency characteristic and phase-frequency characteristic are obtained by mathematical transformation of the power circuit. The frequency response of the circuit is constructed. As a result of the calculations, we will obtain the amplitude frequency response and the phase frequency response. Using the found values of the characteristics, we will build graphs and draw conclusions about how the characteristics depend on the change in parameters and why the graph lines of the graphs are exactly the way they are.
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Li, Li Ping. "Experiment Analysis about Mechanical Properties of Rubber Bushing for Suspension Telescopic Shock Absorber." Applied Mechanics and Materials 670-671 (October 2014): 1008–11. http://dx.doi.org/10.4028/www.scientific.net/amm.670-671.1008.
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The experiments of static and dynamic characteristics of rubber bushing for rear suspension telescopic shock absorber were carried out at four directions such as axial, radial, torsion and yaw, by MTS831 and SAGINOMIYA test system. The tests prove that: rubber bushing has great damping, and rubber bushing has obvious nonlinear characteristic; the dynamic stiffness under low frequency and large amplitude excitation is smaller, while the dynamic stiffness under high frequency and small amplitude excitation is greater; at the same amplitude, the dynamic stiffness increases with the increasing excitation frequency. The test results can provide support for the optimization design of rubber bushing.
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Parovik, Roman. "Frequency characteristics of the fractional oscillator Van der Pol." E3S Web of Conferences 127 (2019): 02010. http://dx.doi.org/10.1051/e3sconf/201912702010.
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Into this paper, the amplitude-frequency and phase-frequency characteristics of the Van der Polar fractional oscillator are studied in order to establish their relationship with the orders of fractional derivatives included in the model equation. Using the harmonic balance method, analytical formulas were obtained for the amplitude-frequency, phase-frequency characteristics, as well as the quality factor – the energy characteristic of the oscillatory system. It was shown that the quality factor depends on the orders of fractional derivatives, and change in their values can lead to both an increase and a decrease in the quality factor.
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Eugene, Kononykhin. "DEVELOPMENT OF PROCEDURES FOR DETERMINING THE PARAMETERS OF AN AIRCRAFT SERVO ACTUATOR." Eastern-European Journal of Enterprise Technologies 1, no. 9 (97) (2019): 11–18. https://doi.org/10.15587/1729-4061.2019.154837.
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Main trends in the use of electro-hydraulic actuators and requirements to parameters were discussed. Necessity of using automatic methods for testing an electro-hydraulic actuator together with the standard hardware of the electronic control unit was substantiated. The procedures for testing the control loop of an electro-hydraulic actuator set forth in this study make it possible to eliminate effects of mutual influence of dynamic and static characteristics of the actuator and hardware of the electronic control unit. Procedures for automatic identification of the actuator model and procedures for automatic determination of main parameters and characteristics of the actuator such as zero shift, dead space, amplitude-frequency, phase-frequency and speed characteristics have been proposed. When introducing the proposed procedures, the problem of processing high-speed characteristics of the actuator having high noisiness associated with the pulse nature of the derivative of the discrete signal of the actuator position (12 bits) was solved. In order to avoid introduction of errors in the waveform, in addition to standard digital filtering methods, it was proposed to approximate the noisy actuator characteristic by means of the Bezier curve. A procedure was proposed to record hysteresis of the speed characteristic by means of a cycle of continuous change of speed of movement of the output link of the actuator during the working stroke. The method for automatic identification of a simplified actuator model can significantly reduce labor costs in processing of experimental data. The parameters of the actuator model obtained for various deviations in parameters and various actuator operating conditions (external factors) can improve quality of synthesis of control algorithms
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Hao, Shijun, Jialiang Xie, Yanbin Liang, Kaiwei Wu, and Bing Yang. "Analysis of the Response Characteristics of Ultra-Wideband Radio Fuze to Interference Signals." Journal of Physics: Conference Series 2891, no. 12 (2024): 122013. https://doi.org/10.1088/1742-6596/2891/12/122013.
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Abstract The response characteristics of the fuze to the interference signal with reasonable characteristic parameters are similar to the real echo signal, which may lead to the confusion of signal processing and recognition system. To solve this problem, this paper analyzes the influence of characteristic parameters of interference signal on the response characteristics of fuze in detail from two perspectives of time domain and frequency domain, Based on the analysis of receiver principle, the amplitude-frequency response model of sampling integral differential circuit is established, and the response characteristics of interference signal are analyzed from the perspective of frequency domain. Based on the analysis of the time-frequency characteristics of the echo signal of the UWB fuze, a time-frequency function cutting method is proposed to evaluate the anti-jamming performance of the UWB fuze. This methodology was applied to the evaluation of the anti-jamming performance of the UWB fuze to sinusoidal amplitude-modulation interference signal and the results show that the theoretical analysis and simulation results are consistent, and the research provides theoretical guidance for the anti-interference of fuze.
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Ma, Liang, Jun Wang, and Guichang Zhang. "The Dynamic Characteristic of a Faulted Rotor System with Multi-Objective Optimization Designed SFD." Applied Sciences 9, no. 17 (2019): 3628. http://dx.doi.org/10.3390/app9173628.
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As an important part of the turbomachinery, the rotor–bearing system has been upgraded to provide a high rotating speed in order to meet the demand of high power production. With increasing demand for stability, the squeeze film damper (SFD) has been widely used in industrial machinery because it can reduce the vibration amplitude and suppress the external force. Usually, it shows inadaptability under the different working conditions where the SFD parameters didn’t change appropriately. Therefore, the reasonable choice of operational parameters of SFD is the key solution that can provide viscous damping effectively and restrain the nonlinear vibration generated by faults. In this paper, the mathematical model of a rotor-ball bearing-SFD system considering the misalignment fault and misalignment-rubbing coupling fault is built first. Then the dynamic characteristics under typical working conditions (ω = 1000 rad/s) of the faulted rotor are discussed. The vibration attenuation effects of the SFD parameters selected by using the multi-objective optimization method on the dynamic responses are analyzed. The results show that when the rotor system operates under different states, the value and the sensitivity of optimization parameters are altered. With no fault, the amplitude of fundamental frequency decrease 23%. With the misalignment fault, the amplitude of the fundamental frequency decreases by 43.4%, the amplitude of 2× fundamental frequency decreases by 27.5%, and the amplitude of 3× fundamental frequency decreases by 66.7%. With the misalignment-rubbing coupling fault, the amplitude of fundamental frequency reduces by 7.4%, the amplitude of 2× fundamental frequency drops by 51.5%, and the amplitude of 3× fundamental frequency drops by 16.8%. Overall, the feasibility of the optimization method of the variable-structured SFD operational parameters for the faulted rotor system is verified. These parametric analyses are very helpful in the development of a high-speed rotor system and provide a theoretical reference for the vibration control and optimal design of rotating machinery.
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Xu, Qian, Zhong-Qi Wang, Wen-Gong Han, and Cheng-Long Yu. "Seismic wavefield model excited by a finite long cylindrical charge." GEOPHYSICS 87, no. 3 (2022): P15—P28. http://dx.doi.org/10.1190/geo2020-0260.1.
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The amplitude-frequency characteristic of a seismic wave excited by explosion sources directly affects the accuracy of seismic exploration. To reveal the effect law related to a cylindrical charge, this research proposes a seismic wavefield model excited by a long cylindrical charge. According to the characteristics of the blasting cavity generated by a finite-length cylindrical charge, the seismic wavefield characteristics of a cylindrical charge excitation are obtained by superposing the seismic wavefield excited by a series of spherical charges. Numerical simulation results show that the calculation error of the blasting cavity characteristics of the theoretical model is within 10%. The comparison with field experimental results shows that the error of the model is within 9.4%. The velocity field of the excited seismic wave is almost the same as that of the spherical charge when the explosion distance to the cylindrical charge with finite length is 16–21 times longer than the charge length, but the frequency of the seismic wave is 30% higher than for a spherical charge. Moreover, the explosive velocity has a certain influence on the amplitude-frequency characteristic of the seismic wave excited by the cylindrical charge. The established theoretical model can accurately describe the amplitude-frequency characteristics of the seismic wavefield excited by a cylindrical charge with finite length.
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Xu, Jinli, Jiwei Zhu, and Feifan Xia. "Modeling and Analysis of Amplitude-Frequency Characteristics of Torsional Vibration for Automotive Powertrain." Shock and Vibration 2020 (August 29, 2020): 1–17. http://dx.doi.org/10.1155/2020/6403413.
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In the present paper, the amplitude-frequency characteristics of torsional vibration are discussed theoretically and experimentally for automotive powertrain. A bending-torsional-lateral-rocking coupled dynamic model with time-dependent mesh stiffness, backlash, transmission error etc. is proposed by the lumped-mass method to analysis the amplitude-frequency characteristic of torsional vibration for practical purposes, and equations of motive are derived. The Runge–Kutta method is employed to conduct a sweep frequency response analysis numerically. Furthermore, a torsional experiment is performed and validates the feasibility of the theoretical model. As a result, some torsional characteristics of automotive powertrain are obtained. The first three-order nature torsional frequencies are predicted. Torsional behaviors only affect the vibration characteristics of a complete vehicle at low-speed condition and will be reinforced expectedly while increasing torque fluctuation. Gear mesh excitations have little effects on torsional responses for such components located before mesh point but a lot for ones behind it. In particular, it is noted that the torsional system has a stiffness-softening characteristic with respect to torque fluctuation.
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Liu and Zhong. "Research on an Electromagnetic Interference Test Method Based on Fast Fourier Transform and Dot Frequency Scanning for New Energy Vehicles under Dynamic Conditions." Symmetry 11, no. 9 (2019): 1092. http://dx.doi.org/10.3390/sym11091092.
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In recent years, electromagnetic interference (EMI) of new energy vehicles, including difference mode symmetric interference and common mode asymmetry interference, has attracted the attention of many scholars. So far, EMI tests for new energy vehicles under steady conditions cannot reflect the actual EMI of the running vehicle. The results of EMI test methods based on fast Fourier transform (FFT) under dynamic conditions have worse frequency resolutions, and frequency/amplitude accuracy has low precision. Therefore, this paper proposes an EMI test method based on FFT and dot frequency scanning (DFS) for new energy vehicles under dynamic conditions. The identification method for accelerating, sliding, and braking conditions is studied. A comprehensive EMI key evaluation index system for new energy vehicles is built, including characteristic points with maximum amplitude, area, ratio, and density coefficients for high-amplitude characteristic points. Among them, the maximum amplitude is an index to evaluate extreme values. The ratio of high-amplitude characteristic points is a comprehensive index to evaluate the overall region. The density coefficient is an index to evaluate the local region. Finally, this method is applied to three vehicles. With the same instruments, by reducing the FFT frequency span, the frequency resolution and frequency accuracy increase. The results indicate that the EMI of new energy vehicles can be tested under dynamic conditions with high accuracy according to the operable evaluation indexes.
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Zeng, Xiang Kun. "Experimental Analysis of Dynamic Characteristic for Automatic Tensioner." Advanced Materials Research 915-916 (April 2014): 49–52. http://dx.doi.org/10.4028/www.scientific.net/amr.915-916.49.
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Experimental method and parameters to investigate the dynamic performances of an automatic tensioner are discussed. Parameters to evaluate the dynamic performances of a tensioner include dynamic stiffness, loss angle and equivalent viscous coefficient. Dynamic stiffness and loss angle can be measured directly, and the equivalent viscous coefficient can be calculated by torque-angular displacement loop which identified with the parameters including dynamic stiffness, loss angle, pre-load torque, pre-load angular displacement, excitation amplitude and excitation frequency. In this paper, the influences of excitation amplitude, excitation frequency and pre-load torque on the dynamic characteristics of tensioner are measured and investigated.
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Wei, Cuicui, Hongen Niu, and Liping Zeng. "Research on Nonlinear Vibration of Dual Mass Flywheel Considering Piecewise Linear Stiffness and Damping." Mathematical Problems in Engineering 2024 (February 7, 2024): 1–11. http://dx.doi.org/10.1155/2024/8683229.
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Nonlinear torsional vibration differential equation of the nested arc-shaped short spring dual mass flywheel (DMF) is established, considering the piecewise linear stiffness and damping of the spring. The first-order approximate analytical solution under sinusoidal excitation and the amplitude–frequency characteristic function are obtained by means of the average method which verified by the Runge–Kutta (R–K) method. The effects of the parameters of input excitation, inertia, and piecewise linear stiffness and damping of DMF on the resonant amplitude, resonant frequency band, and equivalent linear natural frequency of the system are analyzed. The results show that the amplitude–frequency characteristic curve bending and jumping with the changes of excitation frequency and the peak of resonant amplitude can be obviously reduced by increasing the inertia of the primary flywheel and decreasing the inertia of the secondary flywheel. The complex nonlinear dynamic phenomena such as Period 1, quasi-periodic, and chaos are obtained by analyzing the forced vibration response under the different excitation frequencies.
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Zhao, Yan Ping, Zi Long Zhao, and Guo Yun Lu. "Analysis of Steel Rope Shock Absorber Amplitude Frequency Characteristics under the Basic Excitation." Applied Mechanics and Materials 312 (February 2013): 287–91. http://dx.doi.org/10.4028/www.scientific.net/amm.312.287.
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In this paper, the differential equations of the steel rope shock absorber are established under the basic excitation, using the Fourier series expansion method and the Harmonic balance method, the corresponding frequency response equations are derived, then their numerical solutions is got, and the influence of the mass, damping, stiffness, and hysteretic force on the frequency response characteristic is analyzed under the basic excitation. It can be drawn by analyzing and comparing. Under the basic excitation, with the basic simplified mass increasing, the natural frequency will decrease, while the resonance amplitude will increase. With the steel rope damping, stiffness and the foundation damping increasing, the natural frequency will not change significantly, while the resonance amplitude will decrease. With the foundation stiffness increasing, the natural frequency and the resonance amplitude will increase significantly. The equipment mass and steel rope hysteretic force have no significant effect on the frequency response characteristics.
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Abramov, Y., V. Kryvtsova, and A. Mikhailyuk. "ALGORITHM FOR DETERMINATION OF RELIABILITY INDICATOR OF GAS GENERATOR OF HYDROGEN STORAGE AND SUPPLY SYSTEM." Municipal economy of cities 4, no. 164 (2021): 153–57. http://dx.doi.org/10.33042/2522-1809-2021-4-164-153-157.
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An algorithm for determining one of the indicators of reliability of the main element of the hydrogen storage and supply system – a gas generator has been developed. Such an algorithm is an integral part of the general algorithm to ensure the required level of fire safety of hydrogen storage and supply systems. The algorithm involves the implementation of several stages. At the first stage, using the expression for the amplitude-frequency characteristic of the gas generator, the functional dependences for its time constants are obtained. These functional dependencies include the values of the transmission coefficient and amplitude-frequency characteristics, which are determined at three a priori set values of frequency. In the second stage, the amplitude-frequency characteristic of the gas generator is determined. For this purpose, an array of data is used, which characterizes the reaction of the gas generator to the test effect in the form of an abrupt change in the area of its outlet. The amplitude-frequency characteristic of the gas generator is determined numerically, and its parameters are the increase in the pressure in the cavity of the gas generator and the time interval at which this increase is determined. The Kotelnikov-Nyquist-Shannon theorem is used to determine this time interval. At the third stage, the probability of the values of the time constants of the gas generator outside the tolerance zone is determined. For this purpose, models of gas generator time constants and their metrological characteristics are used. In the fourth stage, the probability of failure of the gas generator is determined, for which the information of the previous stage is used. At the last stage, the algorithm for determining the probability of failure of the gas generator of the storage and supply system of hydrogen, which is given in verbal form.
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Xu, Hui, Zeng Tian Yan, Yang Wang, and Song Wei Gao. "Transmission Design of the Ultrasonic Flow Measurement Based on the Correlation Method." Advanced Materials Research 503-504 (April 2012): 1441–44. http://dx.doi.org/10.4028/www.scientific.net/amr.503-504.1441.
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In design of ultrasonic flow measurement, the reproducibility of constant amplitude periodic signal will lead to a not unique time difference based on the correlation method. The aim of this paper is to design a set of amplitude modulation transmitting signal to solve the multiple values calculation of the time difference. The frequency characteristics of ultrasonic probe and the amplitude frequency characteristic of different duty cycle square wave are researched and tested. We cleverly combine the logic device FPGA with the property of the ultrasonic probe to achieve the amplitude modulation waveform in the circuit design. The experimental results show that FET switch controlled by the logic device FPGA can transmit amplitude modulation signal. The measured error of time difference after correlation is not more than 1.62s.
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Li, Yajie, Zhiqiang Wu, Qixun Lan, Yujie Cai, Huafeng Xu, and Yongtao Sun. "The modulation of response caused by the fractional derivative in the Duffing system under super-harmonic resonance." Thermal Science 25, no. 3 Part B (2021): 2357–67. http://dx.doi.org/10.2298/tsci191201126l.
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The dynamic characteristics of the 3:1 super-harmonic resonance response of the Duffing oscillator with the fractional derivative are studied. Firstly, the approximate solution of the amplitude-frequency response of the system is obtained by using the periodic characteristic of the response. Secondly, a set of critical parameters for the qualitative change of amplitude-frequency response of the system is derived according to the singularity theory and the two types of the responses are obtained. Finally, the components of the 1X and 3X frequencies of the system?s time history are extracted by the spectrum analysis, and then the correctness of the theoretical analysis is verified by comparing them with the approximate solution. It is found that the amplitude-frequency responses of the system can be changed essentially by changing the order and coefficient of the fractional derivative. The method used in this paper can be used to design a fractional order controller for adjusting the amplitude-frequency response of the fractional dynamical system.
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Madola, Vladimír, Vladimír Cviklovič, and Stanislav Paulovič. "Analysis of Ultrasound Signal on Reflection from a Sharp Corner Surface: Study of Selected Characteristics Deriving from Regression by Transfer Function." Processes 10, no. 12 (2022): 2644. http://dx.doi.org/10.3390/pr10122644.
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This article deals with the regression analysis of the ultrasonic signal amplitude when the character of the reflection surface has been changed from a planar case to a sharp corner case. The experiment was performed at a measurement distance within the interval from 100 mm to 215 mm. A nonlinear correlation between the amplitude of the ultrasound signal and the measured distance was demonstrated. By analyzing the frequency spectra, a poor nonlinear correlation between the maximum frequency component and the distance vector was found for the sharp corner case versus the planar case, which proved similar nonlinear characteristics as the signal amplitude marker. The strong linear correlation in the distance difference vectors in the amplitude analysis of the ultrasound signal confirmed the hypothesis of a direct relationship between the reflection surface geometric characteristic and the polarity of the difference. The ultrasound signal was identified as a 3rd-order dynamic system. The nonlinear correlation of the steady-state values of the modelled transfer functions versus distance likewise shows the characteristic of the polarity difference or character derivative as a quantification marker of the characteristics of the reflection surface from the geometric point of view.
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Chu, Hai Rong, Bo Liu, and Yue Zhang. "Three-Loop Autopilot Frequency Characteristic Measurement." Applied Mechanics and Materials 494-495 (February 2014): 1332–34. http://dx.doi.org/10.4028/www.scientific.net/amm.494-495.1332.
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In order to measurement frequency characteristic of the missile three loop autopilot, three loop autopilot system model of the missile pitch channel was established. Then the autopilot system open-loop model was analyzed , and also open-loop frequency calculation formula was deduced. On the basis of the autopilot system model, half physical frequency characteristic measurement system was built, and the experimental data were processed by using correlation analysis method. Experimental results shows that when the time delay of measurement system was compensated, three loops autopilot actual cut-off frequency was 47.5rad/s, phase margin was 93°, amplitude margin was infinte, compared with the theoretical value, errors was less than 5%. The correctness of three loops autopilot frequency characteristic measurement method was verified.
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Wan, Di Qing, Bo Lin He, Jin Cheng Wang, and Gen Cang Yang. "Strain Amplitude Dependence of Damping Capacity in High Damping Mg-Based Alloys Continuously Extending to Microplastic Strain." Advanced Materials Research 97-101 (March 2010): 937–40. http://dx.doi.org/10.4028/www.scientific.net/amr.97-101.937.
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An investigation on low frequency strain amplitude dependence damping characteristic of as-cast high damping Mg-based alloys continuously extending to microplastic strain was carried out. Two-stage damping behavior via strain amplitude was particularly reported. The first is the strain amplitude strongly dependent part due to breakaway loss and the second is the strain amplitude weakly dependent part due to microplastic deformation loss, which is also frequency dependent. The damping mechanism is discussed in detail.
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Yong, Yang, Shuai Zhang, and Yan Huai Qu. "HHT Based Analysis on Experiments of Rotor System with Rub-Impact." Advanced Engineering Forum 2-3 (December 2011): 111–16. http://dx.doi.org/10.4028/www.scientific.net/aef.2-3.111.
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Based on the demand of engineering, the motion characteristics and time-frequency properties of rotor system with rub-impact at fixed limiter are studied by experiment. Three typical cases at different rotating speeds are chosen from the experiment. On the basis of traditional amplitude spectrum and shaft center orbit methods, Hilbert-Huang transformation is applied to the fault signals analysis. Fault features are characterized completely and accurately by Hilbert spectrum. It is show that the vibration of the system is with typical characteristic of periodic motions and corresponding time-frequency (instantaneous frequency) -amplitude /energy representations in the rotor system with rub-impact at fixed limiter.
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Modzelewski, Juliusz, and Mirosław Mikołajewski. "High-Frequency Power Amplitude Modulators with Class-E Tuned Amplifiers." Journal of Telecommunications and Information Technology, no. 4 (June 26, 2023): 79–86. http://dx.doi.org/10.26636/jtit.2008.4.903.
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A high-frequency power amplifier used in a drain amplitude modulator must have linear dependence of output HF voltage Vo versus its supply voltage VDD. This condition essential for obtaining low-level envelope distortions is met by a theoretical class-E amplifier with a linear shunt capacitance of the switch. In this paper the influence of non-linear output capacitance of the transistor in the class-E amplifier on its Vo(VDD) characteristic is analyzed using PSPICE simulations of the amplifiers operating at frequencies 0.5 MHz, 5 MHz and 7 MHz. These simulations have proven that distortions of theVo(VDD) characteristic caused by non-linear output capacitance of the transistor are only slight for all analyzed amplifiers, even for the 7 MHz amplifier without the external (linear) shunt capacitance. In contrast, the decrease of power efficiency of the class-E amplifier resulting from this effect can be significant even by 40%
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FAN, Shengping, Jing LI, Linyong LI, Xiaopeng FAN, Hualiang LI, and Nansha GAO. "Theoretical model and experimental study on working characteristics of electromagnetic damper." Xibei Gongye Daxue Xuebao/Journal of Northwestern Polytechnical University 41, no. 4 (2023): 688–96. http://dx.doi.org/10.1051/jnwpu/20234140688.
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An analysis model for electromagnetic damper is proposed in order to obtain the working characteristics of electromagnetic damper under different working conditions. Firstly, the inertia force and the electromagnetic force of electromagnetic damper are calculated, and the friction force is tested. Secondly, by combining the theoretical results and the test data, the working characteristic analysis model for electromagnetic damper is established. Finally, the damping characteristics and energy harvesting characteristics of the electromagnetic damper under multiple working conditions are discussed by using the present model. The working condition characteristic surface of the electromagnetic damper is obtained by using the recovered energy and equivalent damping coefficient as the coordinate plane. The results show that the error between the calculated results and the test results is below 10%. The damping force and output voltage of the electromagnetic damper are positively correlated with excitation frequency and amplitude. The excitation amplitude and frequency influence the energy harvesting characteristic and damping property deeply, respectively. The increase in load resistance reduces the energy regenerative capacity and damping capacity of the electromagnetic damper.
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Власов, В. С., В. Г. Шавров та В. И. Щеглов. "Нелинейное расщепление линии магнитоупругого резонанса в сильно возбужденном феррите". Журнал технической физики 92, № 1 (2022): 62. http://dx.doi.org/10.21883/jtf.2022.01.51853.167-21.
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The nonlinear splitting of magnetoelastic resonance line in powerfully excited ferrite is investigated. It is shown that the amplitude of splited resonance has the same order of value that the amplitude of basis resonance and its frequency is determined by the upper boundary of nonlinear amplitude-frequency characteristic of magnetic system. It is found the threshold character of splitting additional resonance from general. It is determined the possibility of operation of splited elastic resonance frequency by changing of exited magnetic field value which has practical importance.
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Pavlina, Hristova, and Alexandrova Violeta. "AMPLITUDE AND FREQUENCY CHARACTERISTICS OF THE VOCALIZATIONS OF CANIDAE FAMILY, GENUS CANIS." Tradition and Modernity in Veterinary Medicine 8, no. 1 (2023): 65–70. https://doi.org/10.5281/zenodo.8174824.
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The present study aims to present and compare the sounds produced by the representatives of the family Canidae, in particular the genus Canis, in terms of their amplitude and frequency characteristics. The results show that the power generated by the vocal apparatus of wolves is the greatest, compared to that of the domestic dog and the jackal, in which they are the lowest, presented in dB. The reflected values for the frequency characteristic of the sound signals in these three representatives of the genus Canis are inversely related – highest in jackals, again average in dogs and lowest in wolves.
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Chaari, Fakher, Walter Bartelmus, Radoslaw Zimroz, Tahar Fakhfakh, and Mohamed Haddar. "Gearbox Vibration Signal Amplitude and Frequency Modulation." Shock and Vibration 19, no. 4 (2012): 635–52. http://dx.doi.org/10.1155/2012/839420.
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Gearboxes usually run under fluctuating load conditions during service, however most of papers available in the literature describe models of gearboxes under stationary load conditions. Main task of published papers is fault modeling for their detection. Considering real situation from industry, the assumption of stationarity of load conditions cannot be longer kept. Vibration signals issued from monitoring in maintenance operations differ from mentioned models (due to load non-stationarity) and may be difficult to analyze which lead to erroneous diagnosis of the system. The objective of this paper is to study the influence of time varying load conditions on a gearbox dynamic behavior. To investigate this, a simple spur gear system without defects is modeled. It is subjected to a time varying load. The speed-torque characteristic of the driving motor is considered. The load variation induces speed variation, which causes a variation in the gearmesh stiffness period. Computer simulation shows deep amplitude modulations with sidebands that don't differ from those obtained when there is a defective tooth. In order to put in evidence the time varying load effects, Short Time Fourier Transform and then Smoothed Wigner-Ville distribution are used. Results show that the last one is well suited for the studied case.The experimental validation presented at the end of the paper confirms the obtained results. Such results offer useful information when diagnosing gear transmissions by avoiding confusing conclusions from vibration signals.
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Liu, Heng, Jiale Wu, and Yu Zhang. "Coupled Double Closed-Loop Control for an MEMS Resonant Accelerometer." Micromachines 13, no. 10 (2022): 1612. http://dx.doi.org/10.3390/mi13101612.
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There is mutual coupling between amplitude control and frequency tracking control in the closed-loop control of micromechanical resonant sensors, which restricts sensor performance. This paper introduces the principle of an in-plane vibration micromechanical resonant accelerometer with electrostatic stiffness. The characteristic parameters of the microaccelerometer were obtained through computer-aided dimension measurement and an open-loop frequency sweep test of the fabricated microstructure. An accurate numerical model was established based on the accelerometer’s dynamic principle and characteristic parameters. We established the double closed-loop driving analysis model of amplitude automatic gain control and resonant frequency phase-locked tracking. We used the averaging method to analyze the steady-state equilibrium point and the stable condition. We concluded that the integral coefficient can improve the startup overshoot when the amplitude automatic gain control loop satisfies the stability condition. Under the constraint of frequency tracking, the sizeable coefficient of the integrator can improve the system instability of the amplitude control loop. The theoretical analysis and simulation were helpful in the design and debugging of the system circuit.
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Vlasov V. S., Shavrov V. G., and Shcheglov V. I. "Nonlinear splitting of magnetoelastic resonance line in powerfully excited ferrite." Technical Physics 92, no. 1 (2022): 40. http://dx.doi.org/10.21883/tp.2022.01.52531.167-21.
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The nonlinear splitting of magnetoelastic resonance line in powerfully excited ferrite is investigated. It is shown that the amplitude of splited resonance has the same order of value that the amplitude of basis resonance and its frequency is determined by the upper boundary of nonlinear amplitude-frequency characteristic of magnetic system. It is found the threshold character of splitting additional resonance from general. It is determined the possibility of operation of splited elastic resonance frequency by changing of exited magnetic field value which has practical importance. Keywords: ferromagnetic resonance, magnetoelastic interaction, nonlinear vibrations.\
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Wang, Jing, and Jianqiang Sun. "Two types of scale effects on the nonlinear forced vibration of axially moving nanobeams." International Journal of Modern Physics B 34, no. 10 (2020): 2050095. http://dx.doi.org/10.1142/s0217979220500952.
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Various non-classical continuum mechanics models appearing in previous studies cannot perfectly explain the mechanical properties of micro- and nanomaterials. Establishing a reasonable continuum mechanics model that comprehensively reflects the scale effect on material deformation is of great practical significance for objectively explaining the variation law of mechanical properties of micro- and nanomaterials under the combined action of different scale effects. Based on nonlocal strain gradient theory, a new scale-dependent model is proposed for axially moving nanobeams. In this study, an asymptotic expansion is performed using the multiscale time method to obtain the amplitude-frequency response curve of the equilibrium solutions for the forced vibration problem. Afterwards, the effects of various system parameters, especially the scale parameters, on the resonance curve are examined. Finally, the effects of nonlocal parameters and material characteristic length parameters on the amplitude-frequency response curves are investigated through typical numerical examples. The numerical results show that the nonlocal parameters promote the emergence of the main resonance, whereas the material characteristic length parameters suppress the emergence of the main resonance. Moreover, these parameters also affect the response amplitude and the skewness and jumping point of the amplitude-frequency characteristic curve.
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Chen, Tao, Songbai Xue, Peizhuo Zhai, Bo Wang, and Weimin Long. "Study on Penetration Sensing Method Based on Pool Oscillation and Arc Voltage during Pulsed GMAW." Applied Sciences 10, no. 8 (2020): 2735. http://dx.doi.org/10.3390/app10082735.
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The internal relations among the oscillation characteristics of the weld pool, the voltage signal curve and the penetration status of the weld joint in pulsed gas metal arc welding were investigated by using high-speed camera and image analysis system to extract characteristics of weld pool oscillation. The results show that the amplitude of weld pool oscillation decreased with decreasing weld penetration. An abrupt change occurred in the frequency components and amplitude of weld pool oscillation, accompanying the transition from partial to full penetration. The voltage signal curve lost the oscillation frequency characteristic of the pool, due to the curvature of the weld pool surface. While similar to the oscillation amplitude, the fluctuation of the voltage signal caused by the weld pool oscillation reflected the penetration of the weld pool. The abrupt transition in the fluctuation amplitude of the voltage signal in the base duration from partial penetration to full penetration may be used to sense the penetration of the weld pool in real time.
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Belov, Alexey S. "Features of generation and propagation of the extremely low frequency waves excited in the ionosphere under the powerful HF radioemission influence." Physics of Wave Processes and Radio Systems 24, no. 4 (2022): 53–62. http://dx.doi.org/10.18469/1810-3189.2021.24.4.53-62.
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The experimental results of the extremely low frequency emission characteristics excited in the outer ionosphere under the ionospheric plasma heating by high-latitude EISCAT facility are presented. The experiments have been conducted in the period of 20062010 yr. using two main schemes of extremely low frequency generation including the impact of the heating facility amplitude modulated emission and two unmodulated pump waves with the frequency detuning. In-situ measurements of the plasma wave disturbances were performed at the outer ionosphere heights using on-board equipment of DEMETER microsatellite. In work the spatial, amplitude and spectral characteristics of the generated extremely low frequency emissions are determined. It is shown that the characteristic size of the extremely low frequency emission is about 400600 km along the trajectory of the DEMETER microsatellite. The registration area spatial position is determined by both the applied generation scheme and the background plasma density distribution. The extremely low frequency emission electric field strength at the Earths outer ionosphere heights is 50330 V/m.
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CHEN, YANQING, and LIUQING PEI. "ANALYSIS OF THE RECOVERED SIGNAL IN SYNCHRONIZED CHUA’S COMMUNICATION SYSTEM." International Journal of Bifurcation and Chaos 06, no. 08 (1996): 1595–600. http://dx.doi.org/10.1142/s0218127496000965.
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The recovered message signal in the synchronized Chua’s system, which is proposed for secure communications, is analyzed by means of both numerical simulations and analytical methods. The results show that the characteristic of “frequency response” of the system is independent of the amplitude of the input message signal, and the amplitude of the recovered signal is suppressed by the system in the lower frequency range and amplified in the higher frequency range. Specifically, we find that, as the frequency of the input signal increases continuously, there is a band of frequency over which a resonance type of phenomenon occurs in the system whereby the input message’s amplitude is amplified, but the location of this band lies beyond the range of the main spectrum of the chaotic driving signal. The phase difference between input signal and output signal is also obtained. Furthermore based on numerical simulations, the characteristic frequency response of a synchronized Lorenz’s system is given, which also shows a band of resonance in the lower range of frequencies.
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Pigulevskiy, Petro, Yuliia Semenova, Yurii Lisovyi, Oleksandr Kendzera, and Serhii Kravets. "Amplification effects of ground motion due to the local geology of the building site in the cities of Kyiv, Kryvyi Rih, Odesa." IOP Conference Series: Earth and Environmental Science 1348, no. 1 (2024): 012088. http://dx.doi.org/10.1088/1755-1315/1348/1/012088.
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Abstract The results of the research presented in the article elucidate the importance of taking into account the amplitude-frequency characteristics of soil stratum models in the context of seismic safety of construction objects on the territory of Ukraine, in different regions. The presented results of the analysis of the calculated amplitude-frequency characteristics of models of soil environments for different regions of Ukraine reveal that the amplification of vibrations by soils has a complex nature that depends on many factors and can differ significantly for different construction sites. We have shown that during the earthquake-resistant design of buildings and structures, it is necessary to properly take into account the properties of soil complexes under the research site, which can significantly increase oscillations at “resonant” frequencies. The article examines in detail the features of amplitude-frequency characteristic models of soil strata for different geological conditions in Kyiv, Kryvyi Rih and Odesa. The purpose of this study is to compare these characteristics and develop recommendations for reducing risks associated with seismic hazards.
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Li, Hai Feng, Yu Zhi Luo, Xiao Long Zhang, and Deng Pan. "Vehicle Body and Wheel Motion Simulation Platform Based on LabVIEW." Applied Mechanics and Materials 241-244 (December 2012): 2113–19. http://dx.doi.org/10.4028/www.scientific.net/amm.241-244.2113.
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The work in the paper constructed a platform for vehicle’s controllability and stability study conveniently and efficiently. Based on the dynamic model of the two-mass vibration system of vehicle body and wheel, the paper builds a vibration platform using the graphical programming software LabVIEW. It establishes a sinusoidal input road surface model, simulates the sinusoidal road surface under different amplitude and frequencies, and makes it the excitation source of the vibration system. It also obtains the curves of the amplitude-frequency characteristic of vehicle body and wheel displacement on the pavement displacement, and the time-domain response and amplitude-frequency characteristic curve of the body acceleration, suspension spring dynamic deflection and wheel relative dynamic load. This simulation platform provides an intuitive and effective method for vehicle ride comfort both in time domain and frequency domain.
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Fernanda, E., A. Bilqis, L. Julio, et al. "Early Result for Microtremor Characteristic Observation in Merapi and Merbabu." IOP Conference Series: Earth and Environmental Science 873, no. 1 (2021): 012077. http://dx.doi.org/10.1088/1755-1315/873/1/012077.
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Abstract The arc magmatism and volcanic activity in Java are dominated by the subducting plate of Indo-Australian into the Eurasian plate. Merapi volcano is located in Central Java and known as one of the most active volcanoes in the world. Several studies have tried to estimate the magma reservoir zone in Mt. Merapi and suggested multiple layers of reservoirs with the shallow one at 1-2 km and a deeper at 6 -9 km or 15 km. The Low-Frequency Passive Seismic is one method to analyze the frequency spectrum below the recording station. Previous related studies show a promising a relation between hydrocarbon reservoir and higher amplitude at vertical component at a frequency between 0.1 – 6 Hz. An observation at the volcano sites have also been reported to display a different spectrum amplitude at the vertical component. This study exploited the same method in LFPS to analyze the frequency spectrum at Mt. Merapi and Mt. Merbabu. We use seismic data from the DOMERAPI temporary seismic network installed in the neighborhood of Merapi and Merbabu volcano. We analyze 53 broad-band seismometers data from October 2013 to mid-April 2015. We also add several stations from MERAMEX network instruments to compare spectrum analysis outside the Merapi and Merbabu volcano. We also removed some tele-seismic and regional events from the data to better analyze the LFPS signal. We have seen a higher amplitude in vertical component near Mt. Merapi and will proceed to analyze all stations.
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Nazarov, V. E., and S. B. Kiyashko. "NONLINEAR EFFECTS IN CRYSTALLINE SOLIDS WITH SATURATION OF AMPLITUDE-DEPENDENT INTERNAL FRICTION, DECREASING WITH IN-CREASING FREQUENCY." Физика металлов и металловедение 124, no. 6 (2023): 467–76. http://dx.doi.org/10.31857/s001532302360020x.
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As a result of modification of quasi-static elastic and inelastic hysteresis, dynamic hysteresis equations of state of crystalline solids with frequency-dependent saturation of amplitude-dependent internal friction decreasing with increasing frequency are proposed. The nonlinear propagation of initially harmonic longitudinal elastic waves in rods made of such materials is investigated by the perturbation method. Numerical, graphical and comparative analysis of the obtained solutions is carried out and characteristic amplitude-frequency dependenc-es of nonlinear wave effects are revealed. A method for determining the type of dynamic hysteresis for crystal-line solids with frequency-dependent saturation of amplitude-dependent internal friction is proposed.
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Qiang, Yan, Yingzhou Wang, Lan Luo, Gang Wang, Yuyang Zhao, and Liejiang Wei. "Method for filtering proportional valve-frequency-response test data containing impulsive noise." Advances in Mechanical Engineering 11, no. 3 (2019): 168781401983629. http://dx.doi.org/10.1177/1687814019836298.
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Impulsive noise, generated by inverters and other equipment used in the field, tends to easily enter test channels in scenarios where continuous frequency conversion signals are employed to test the frequency response of electrohydraulic proportional valves. Interference caused by such noise reduces the signal-to-response ratio of response signals, thereby influencing the accuracy of the frequency response of proportional valves. To address this concern, in this article, an integrated filtering method that combines ensemble empirical mode decomposition with median filtering is proposed. The proposed method first preprocesses the response signals of the systems and subsequently obtains frequency-response diagrams using fast Fourier transforms. Simulation results demonstrate that the proposed method reduces the root mean square error associated with the amplitude–frequency characteristic curves of the proportional directional valve considered from 2.1 to 0.3, whereas that associated with phase–frequency characteristic curves is reduced from 78.0 to 1.4 with signal-to-noise ratios in the high-frequency band being of the order of –20 dB. Experimental results also reveal that the proposed method reduces the root mean square error of the amplitude–frequency characteristic curves of the proportional directional valve by 52.5% and that of the phase–frequency characteristic curves by 71.2%.
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Xing, Ya Min, Sheng Hu Liu, and Dong Xu Wang. "Design and Research on Piezoelectric Acceleration Geophone." Advanced Materials Research 468-471 (February 2012): 826–30. http://dx.doi.org/10.4028/www.scientific.net/amr.468-471.826.
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A kind of piezoelectricity acceleration geophone is studied and discussed. carried on its amplitude frequency, phase-frequency characteristic theoretically, obtained the primary factor of the influence on frequency response, and improved in the piezoelectric crystal choice and geophone structure. The theory and the field test result indicated that, this piezoelectricity acceleration geophone has better response characteristic on low frequency and the high-frequency as well as a higher sensitivity, it is one better detection method.
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Brzhezitsky, V. O., Y. O. Haran, A. O. Derzhuk, O. R. Protsenko, Y. O. Trotsenko, and M. M. Dixit. "Ultimate effect of non-identity of capacitive elements of high-voltage arm on frequency characteristics of voltage divider (analytical research)." Electrical Engineering & Electromechanics, no. 4 (July 29, 2021): 46–52. http://dx.doi.org/10.20998/2074-272x.2021.4.06.
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Purpose. Determination in the analytical form of the maximum limiting influence of the non-identity of the capacitive elements of the high-voltage arm on the amplitude-frequency characteristic and phase-frequency characteristic of the voltage divider with parallel-series connection of R-, C-elements of the high-voltage arm. Methodology. Based on the previously developed theory of broadband voltage dividers with parallel-series connection of R-, C-elements, analytical expressions for amplitude-frequency and phase-frequency characteristics of the voltage divider are obtained and investigated taking into account the limit case of non-identical capacitive elements of high-voltage arm. Results. The nature of the dependencies of the frequency characteristics of the broadband voltage divider on the value of the tolerance of the capacitive elements of the high-voltage arm, the division factor of the voltage divider in a wide range of frequency changes is determined. Simplified approximating expressions for the maximum values of frequency characteristics of the voltage divider are proposed and their error is determined. Originality. For the first time in the analytical form the limiting influence of non-identity of capacitive elements of a high-voltage arm of a voltage divider on its frequency characteristics is considered. A mathematical model of this influence is constructed and the limit values of frequency characteristics of the voltage divider are determined. Practical value. It is recommended to introduce into the normative documentation of broadband voltage dividers the corrected value of the division factor, which allows to significantly reduce the deviation of the actual value of the division factor of the voltage divider from the normalized value in a wide range of frequency changes.
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Brzhezitsky, V. O., Y. O. Haran, Y. O. Trotsenko, O. R. Protsenko, A. O. Derzhuk, and M. M. Dixit. "Ultimate effect of non-identity of resistive elements of high-voltage arm on frequency characteristics of broadband voltage divider (analytical research)." Electrical Engineering & Electromechanics, no. 3 (April 23, 2023): 52–58. http://dx.doi.org/10.20998/2074-272x.2023.3.08.
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Purpose. Determination in the analytical form of the maximum limiting influence of the non-identity of the resistive elements of the high-voltage arm on the amplitude-frequency characteristic and phase-frequency characteristic of the voltage divider with parallel-series connection of R-, C-elements of the high-voltage arm. Methodology. Based on the previously developed theory of broadband voltage dividers with parallel-series connection of R‑, C-elements, analytical expressions for amplitude-frequency and phase-frequency characteristics of the voltage divider are obtained and investigated taking into account the limit case of non-identical resistive elements of high-voltage arm. Results. The nature of the dependencies of the frequency characteristics of the broadband voltage divider on the value of the tolerance of the resistive elements of the high-voltage arm, the division factor of the voltage divider in a wide range of frequency changes are determined. Simplified approximating expressions for the maximum values of frequency characteristics of the voltage divider are proposed and their error is determined. Originality. For the first time in the analytical form the limiting influence of non-identity of resistive elements of a high-voltage arm of a voltage divider on its frequency characteristics is considered. A mathematical model of this influence is constructed and the limit values of frequency characteristics of the voltage divider are determined. Practical value. It is recommended to introduce into the normative documentation of broadband voltage dividers the corrected value of the division factor, which allows to significantly reduce the deviation of the actual value of the division factor of the voltage divider from the normalized value in a wide range of frequency changes.