Phase Frequency Response Research Articles

The analysis of conditions for preservation of gain-frequency and phase-frequency characteristics optimality under analog and digital filters transformation

Prototype filters have wide usage for the design of filters with required quality indexes (QI) of gain-frequency response (GFR). The designed filter is obtained from a prototype filter b means of frequency transformation, which preserves these QI. But most of employed frequency transformations result in variations of QI of phase-frequency response (PFR). In this paper we proposed to use prototype filters that are Pareto-optimal for QI of GFR and PFR. Transfer functions of these filters may be found by means of heuristic optimization algorithms. This method will be efficient if the frequency transformation preserves the optimality of filters. It was shown that frequency transformation has this feature if it preserves the result of QI comparison (more or less) for filters with equal orders. Compliance of this criterion was checked for bilinear transformation of analog low pass filters (LPF) into digital LPF and for Konstantinidis transformation of digital LPF into other digital LPF. The analysis showed that Pareto-optimality for QI of GFR and PFR is preserved if the delay-frequency characteristic of the filter has a minimum at zero frequency and has a maximum at the upper boundary of the pass band. These conditions are complied for LPF with sufficiently small unevenness of GFR in the pass band and sufficiently fast decline of GFR at higher frequencies. Examples confirming these conclusions are given.

Tunable Substrate Integrated Waveguide Phase Shifter Using High Dielectric Constant Slab

This letter presents a low-cost, low-profile, and high-performance $Ka$ -band continuously tunable substrate integrated waveguide (SIW) phase shifter. The proposed phase shifter consists of a slot cut on the SIW’s broad wall and a high dielectric constant slab over the slot. The phase-shifting mechanism is based on perturbing the electric field of the SIW’s fundamental mode, TE10-like, by putting a high dielectric constant slab over the slot of SIW structure to create slow wave phenomena. A prototype is designed, fabricated, and measured. The fabricated phase shifter exhibits linear phase–frequency response behavior with an average insertion loss less than 1.5 dB with an insertion loss variation less than 0.5 dB over a phase shift range of 275° in the operating frequency band (29–31 GHz). The phase shifter consumes a maximum of 25-mW power.

Nonconventional measurements on insulation materials high voltage bushings and power cables using frequency response analysis method

AbstractPower utilities desire an alternate noninvasive test method for assessing the diagnostic status of power apparatus. The primary reason is to minimize the economic constraints and ensure lifetime and reliability of power apparatus within shorter duration. In this context, frequency response analysis (FRA) method is increasingly recommended. The underlying principle of fault diagnosis using FRA method focuses on correlating the insulation condition to the changes in the magnitude and phase frequency response function. Existing practices validates the usage of FRA method in ascertaining the insulation integrity of transformers. Further attempts to expand the potential of FRA in method in determining the insulation status of power apparatus other than transformers, lack scientific and experimental evidence. To fill this gap, a research on using FRA method in assessing the insulation condition of high voltage bushings and power cables is initiated. Initially, test samples of insulation materials that are commonly used in bushings and cables are selected. The chosen samples are prepared in such a way that they represent common defect conditions that inflict premature material degradation and failures. These samples are grouped accordingly, placed on test cells, subjected to nonconventional FRA tests and their diagnostic status are respectively ascertained through comparative analysis. Following this, the pertinent findings are validated on actual bushings and power cables installed on a power transformer. In summary, the findings of this studies not only validate the usage of FRA method but provides the missing scientific and technical evidences and indices that could be used for diagnosing power apparatus.

Hydroelastic Response of an End Wall Interacting with a Vibrating Stamp via a Viscous Liquid Layer

The mathematical modelling of a vibrating stamp interaction with a flexible restrained end wall (bellows) of a narrow channel via a viscous incompressible fluid is carried out. The narrow channel formed by two parallel walls and filled with a viscous liquid is investigated. The liquid motion in the channel is considered as a laminar one. The bottom channel wall is absolutely rigid, and the top one is the absolutely rigid vibrating stamp. At the right edge of the channel, the end wall with flexible restraint (bellows) is installed, and at the left one, there is a free liquid flow. The problem of longitudinal hydroelastic vibrations of the channel end wall is formulated and solved analytically. The distribution laws of velocities and pressure in the fluid layer along the channel are found. The motion law of the channel end wall is determined. The amplitude frequency and phase frequency responses of the end wall for steady-state harmonic oscillations are constructed. The mathematical modelling has shown the possibility of damping the channel end wall (bellows) vibrations by changing the distance between the channel walls or by changing the liquid viscosity in the channel.

ДОСЛІДЖЕННЯ ДИНАМІЧНИХ ХАРАКТЕРИСТИК ПРОЦЕСУ ШЛІФУВАННЯ ЦИЛІНДРИЧНИХ ПОВЕРХОНЬ ПЕРИФЕРІЄЮ ОРІЄНТОВАНОГО КРУГА В РЕЖИМІ ЗАТУПЛЕННЯ НА ВЕРСТАТІ ВЗ208 Ф4

Urgency of the research.. A large number of parts in mechanical engineering that have surfaces of rotation, get the final accuracy of size, shape, and roughness in circular grinding operations. The study of grinding parameters with crossed axes of the wheel and the part in the blunting mode is an urgent task, as it will increase processing productivity, product accuracy and tool stability and ensure higher competitiveness of products in various fields of mechanical engineering. Target setting. In the final grinding operations, it is desirable to create conditions and mode that ensure the operation of the wheel in the mode of predominant blunting or partial self-sharpening, when there is a slight dimensional wear. This mode is characterized on the one hand by increased blunting of abrasive grains and salinization of the surface of the wheel and on the other helps to preserve the shape of the wheel after editing, so it is necessary to conduct dynamic studies whose results are taken into account when constructing the grinding process. Actual scientific researches and issues analysis. Analysis of recent research and publications. Scientific school under the leadership of Dr., Prof. Kalchenko VI the method of circular grinding in the mode of self-sharpening with crossed axes of a detail and preparation is investigated and the ways of increase of stability of abrasive wheels and accuracy of processing are offered. Uninvestigated parts of general matters defining. Selection of previously unexplored parts of the general problem. Investigation of the dynamic characteristics of the grinding process in the blunting mode on the machine VZ208 F4. The purpose of the article. To provide high indicators of the accuracy of the sizes, low roughness and undulation of the processed surfaces when grinding in the blunting mode. Carry out a dynamic calculation of the spindle assembly and establish the areas of its resonant operation, construct the amplitude phase-frequency response (AFCH) and determine the dynamic stability of the system. The presentation of the main material. There are grinding in the mode of self-sharpening and the predominant blunting of the tool. In the self-sharpening mode, the wear of the grinding wheel leads to a change in its original (correct) geometric shape, which, in turn, intensifies the vibrations of the process system, reduces dimensional accuracy and the formation of corrugated parts on the machined surfaces. In the final grinding operations, it is desirable to create conditions and mode that ensure the operation of the wheel in the mode of predominant blunting or partial self-sharpening, when it provides a slight dimensional wear. Conclusions and suggestions. The dynamic characteristics of the process of grinding cylindrical surfaces by the periphery of the oriented circle in the mode of blunting on the machine VZ208 F4 are investigated in the work. The conducted researches allow to minimize cutting forces, to establish areas of resonant work of the machine, to increase intervals between edits and stability of a grinding wheel, to provide higher accuracy and quality of the processed surfaces, and also to increase productivity of processing.

Dynamics of a three-parameter electromagnetic vibration energy harvester considering electromechanical coupling

The paper concerns the dynamic responses and vibration energy harvesting characteristics in an electromagnetic vibration energy harvester comprising three-parameter mechanical vibration subsystem. For completeness and comparison, a two-parameter vibration energy harvester is also presented. The analytical expressions of the amplitude-frequency and phase-frequency responses of the inertial mass and the current in the electrical circuit are respectively derived by applying dimensionless method to the studied two- and three-parameter dynamic systems. Considering the effects of different types of ambient excitation, a single-frequency harmonic load and a periodic load are introduced into the analytical expressions on the dynamic performance of the vibration energy harvester. First of all, the influences of the designing parameters from the mechanical vibration subsystem and the electrical circuit subsystem on the vibration energy harvester are investigated. For evaluating the effects due to introducing the three-parameter mechanical vibration component, comparisons are made between two- and three-parameter vibration energy harvesters to convert the ambient excitations into electrical energy. And then, the expressions of the dimensionless average power which delivered into an electrical load under a single-frequency harmonic excitation or a periodic excitation are derived. The calculating results show that the energy conversion efficiency is enhanced significantly by changing the mechanical damping efficiency and the stiffness ratio for the three-parameter mechanical component of the energy harvester. At the same time, the average power of the three-parameter vibration energy harvester, which delivered into the electrical load, is also improved. However, the influences of the electrical circuit component on the ambient energy harvesting can be omitted when keeping the designing parameters of the mechanical part constant.

The upper frequency limit of dynamic cerebral autoregulation.

Dynamic cerebral autoregulation (CA) is expressed by the temporal pattern of cerebral blood flow (CBF) recovery following a sudden change in arterial blood pressure (BP). Transfer function analysis of BP as input and CBF velocity as output can express dynamic CA through its amplitude (or gain) and phase frequency responses. The upper frequency limit (FupLim ) at which dynamic CA can operate is of considerable physiological interest and can also provide additional information about worsening CA due to disease processes. In healthy subjects FupLim was strongly dependent on arterial changes induced by four different breathing manoeuvres. The considerable intersubject variability in FupLim suggests that fixed frequency bands should not be adopted for averaging values of gain and phase in studies of dynamic CA. Dynamic cerebral autoregulation (CA) can be expressed in the frequency domain by the amplitude and phase frequency responses calculated by transfer function analysis of arterial blood pressure (BP) and cerebral blood flow velocity (CBFV). We studied the effects of arterial ( ) on the upper frequency limit (FupLim ) of these responses and its intersubject variability. Twenty-four healthy subjects (11 female, age 36.0±13.4years) were recruited. Recordings of CBFV (transcranial Doppler ultrasound), BP (Finometer) and end-tidal CO2 ( , capnography) were performed during 5min at rest (normocapnia) and during four breathing manoeuvres: 5% and 8% CO2 in air and hyperventilation targeting reductions of 5 and 10mmHg compared to normocapnia. FupLim was determined by the break point of the autoregulation index (ARI) curve as a function of frequency when the phase response was gradually set to zero. The five breathing conditions led to highly significant differences in (p<0.0001), CBFV (P<0.0001), ARI (p<0.0001) and FupLim (p<0.0001). FupLim ranged from 0.167±0.036Hz at the lowest values of hypocapnia (28.1±1.9mmHg) to 0.094±0.040Hz at the highest level of hypercapnia (41.7±5.4mmHg), showing a correlation of r=-0.53 (p<0.001) with . These findings reinforce the key role of in CBF regulation. The considerable intersubject variability of FupLim suggests that fixed frequency bands should not be adopted for averaging values of gain and phase in dynamic CA studies, and that the higher frequency band (0.20-0.40Hz), in particular, does not contain relevant information about dynamic CA. Further investigations are needed to assess the information value of FupLim as a marker of dynamic CA efficiency in physiological and clinical studies.

A novel hybrid coordinates multiple decoupled phase‐locked loop under nonideal grid conditions

AbstractA novel hybrid coordinates multiple decoupled phase‐locked loop (HCMD‐PLL) is presented to improve the performance of the PLL under nonideal grid conditions. Based on the Clark transform and the first‐order low‐pass filter, the complex coefficient filter is derived to analyze phase‐locked loop. It is different from the phase‐locked loop with a complex coefficient filter. On this basis, the multiple‐complex‐coefficient band‐pass filter of HCMD‐PLL is derived, and the equivalent transfer function of the decoupling of the fundamental positive sequence, negative sequence and harmonic components is obtained, and the magnitude and phase frequency responses are analyzed. The fundamental positive sequence component is extracted without phase shift and amplitude attenuation under the nonideal grid conditions, eliminating the effect of specific‐order harmonics components because the amplitude is attenuated to zero. And the specific‐order harmonic component can also be extracted precisely. The interaction from the various specific components is eliminated. The stability of the system is analyzed by the pole distribution of the closed‐loop system. The stationary αβ coordinate system for PLL is adopted to suppress the change of the grid voltage. Simulation and experimental results verify the effectiveness of the HCMD‐PLL. © 2019 Institute of Electrical Engineers of Japan. Published by John Wiley &amp; Sons, Inc.

Automated measuring system for studies of microwave filters in a wide frequency range

The structure of an automated measuring system for the study of the frequency characteristics of microwave filters in a wide frequency range is given. It is based on a handheld probe station, a vector network analyzer, a vector signal analyzer and a signal generator. It provides automation of research and determination of the main parameters of microwave filters – amplitude-frequency characteristics, phase-frequency response, group delay differences, level signal attenuation in stop band. The function of documenting the results of measuring the parameters of microwave filters allows not only in real time, but also in post-processing to analyze and compare the characteristics of microwave filters in the frequency range from 10 MHz to 24 GHz.

Geophone Equivalent Circuit for Simulation Tasks in SPICE Packages

Introduction. In modern electronic equipment the inductive seismic receivers (geophones) are the most widespread as sensors for registration of seismic signals. In developing seismic receiving devices, the most significant attention is paid to input amplifiers, which are directly connected to the geophones. Depending on the type of seismic research it is necessary to allocate specific ranges of input frequencies. For filtration and frequency response form correction to geophone is adding additional circuits. Therefore, the work of the geophone should be considered in conjunction with the input cascades of the seismic waves receiver. The main part. The main parameters from the documentation of geophones are analyzed and parameters for the assess of created model adequacy are selected. The analysis was carried out on an example of the model GS-ONE produced by Geospace (USA). The structure of the geophone and the principle of electromechanical analogies for equivalent circuit creating are considered. The equivalent circuit, taking into account parasitic parameters, and the measuring and calculating methods ofthe schemeelements are given. The influence on the work of the geophone of the shunt resistance connected to the output geophone terminals is considered.The calculation of the circuit elements according to the following method is carried out on the example of the GS-ONE geophone, the amplitude and phase frequency responses as the results of simulation in the package of NI Multisim are introduced. The simulation results are assessed according to their similarity with geophone parameters from documentation. Conclusions. The accuracy of the given model is increased compared to known models due to the consideration of the presence of the output geophone branch in the form of inductance coil and its parasitic parameters. This method can be used for equivalent circuit parameters calculation and for modeling in electronic simulation packages. The model does not take into account absolutely all processes in geophone, which leads to deviation in the amplitude values of amplitude frequency response to 8% and the deviation of phase frequency response to 2 degrees. However, further additions to the model will complicate its use in engineering practice and from this point of view it is not expedient.

Nonlinear Vibration Analysis of Generator Rotor of a Military General Mobile Power Plant

The generator is the core component of the military general mobile electric power plant. In general, the rotor of generator has different degrees of eccentricity which affect the operation and even cause system failure. To explore the vibration characteristics of the rotor, the rotor of generator is taken as research object. A Jeffcott rotor system with cubic terms is established and reduced to Duffing equation. The multi-scale method is used to solve the first approximate solution of the forced vibration. The amplitude-frequency, phase-frequency response equation and the resonance conditions are obtained. The influence of different mechanical parameters on the lateral vibration and the main resonance of the system are studied: eccentricity and the stiffness have little effect on the amplitude variation, but have a great influence on the stability region; the main resonance frequency and the excitation change the magnitude of the system common amplitude value; the damping not only has a great influence on the common amplitude value, but also changes the response and phase.

Active and Time Delay Controls on Vibrations of the Micro-Electro-Mechanical System (MEMS) Resonator

In this paper, the active control and time delay control are applied on a nonlinear mechanical system subjected to external force to reduce the resulted vibration. The system is modeled by a unique nonlinear differential equation. The multiple scale perturbation technique (MSPT) was applied to obtain an approximate solution and showing the response equation. The stability of the system at primary resonance case is investigated using both of phase plane and frequency response equation. Numerical solution is obtained using Runge – Kutta forth order method.Also, MATLAB 14.0 and Maple 18.0 programs were used to study the numerical solution and the effect of the different parameters for the response of the nonlinear dynamic mechanical system.

A Coil Constant Calibration Method Based on the Phase-Frequency Response of Alkali Atomic Magnetometer

We propose an in-situ method to calibrate the coil constants of the optical atomic magnetometer. This method is based on measuring the Larmor precession of spin polarized alkali metal atoms and has been demonstrated on a K-Rb hybrid atomic magnetometer. Oscillation fields of different frequencies are swept on the transverse coil. By extracting the resonance frequency through phase-frequency analysis of electron spin projection, the coil constants are calibrated to be 323.1 ± 0.28 nT/mA, 108 ± 0.04 nT/Ma, and 185.8 ± 1.03 nT/mA along the X, Y, and Z directions, respectively.

2P5-2 Effect of phase frequency response of hydrophone sensitivity on instantaneous acoustic pressure of diagnostic ultrasound

2P5-2 Effect of phase frequency response of hydrophone sensitivity on instantaneous acoustic pressure of diagnostic ultrasound

WAVELET ANALYSIS OF THE El NIÑO - LA NIÑA PHENOMENON DYNAMICS AND ITS FORECASTING

Having calculated the frequency content of a solar constant, solar activity from the time series in (1610-2012), the El Niño curve in both (1470-1984) and (1950-2075), it has been found that the frequency content of an El Niño - La Niña curve is induced by frequency contents of solar variables. The frequency contents of the variables have been calculated by developing their wavelet phase-frequency responses. Instantaneous phase differences of the solar variables curves CO2(t), global surface air temperature, El Niño in the two time intervals, in (1891-1950) and (1950-2009), have been calculated; linear approximations with coefficients of instantaneous phase differences between variables in these time intervals have been obtained. Based on relational approximation coefficient analysis of the two time intervals, it has been identified that rising surface air temperature and El Niño alike had been markedly influenced by solar variables variations during the first time interval, with the El Niño rise being affected by that of the surface air temperature amid the global climate change in 1950-2009. The predicted El Niño curves have been obtained from the 2015/16 to 2050 time period by the trained data curve in 1950-2015/16 in two versions as the sum of predicted wavelet approximating and detailing components of the original signal according to the Mallat rule. The accuracy of the predictive El Niño curve values is » 83%. On the obtained curves, coordinates of local maximum and minimum are nearly matching. Wavelet phase-frequency response imaging of one curve reflects an impact on El Niño - La Niña variations of the Earth's solar and climatic variables in the past and the future alike.

Wave properties of the group delay correctors based on coupled strip-lines with different inphase and antiphase wave phase velocities

ABSTRACTWe considered the effect of the imbalance of the inphase and antiphase electromagnetic wave phase velocities on wave properties of group delay time corrector circuits based on contradirectional and transdirectional couplers. We obtained equations for the analysis of the wave dissipation matrix frequency response as a function of the resistance of the elements defining the specified phase frequency response and group delay. In addition, we obtained the group delay time difference as 3 ns under return and minimum insertion losses in the range of 17–20 dB in the 0.35–0.7 GHz bandwidth. We showed that systems based on contradirectional couplers can exhibit a deviation of 20% in the phase velocity ratio of the inphase and antiphase waves without the degradation of the corrector performance. It was found that the increase in the imbalance of phase velocities results in the narrowing of the operating bandwidth, while a transdirectional coupler enables the increase of the passband while maintaining the specified return losses.

A window of multistability in Genesio-Tesi chaotic system, synchronization and application for securing information

In this work, we further investigate the dynamics of the Genesio-Tesi chaotic system which consists of a relatively simple jerk circuit with a quadratic nonlinearity. We complete and enrich the results obtained by Aceng et al. (2016). For this reason, we focus our interest in multistability generation and chaos synchronization as well. By using simulation software tools like PASCAL compiler, Orcad PSPICE and MATLAB, these properties have been characterized via common nonlinear tools including phase portraits, temporal responses, frequency responses, bifurcation diagrams and maximum lyapunov exponent plots. The analysis shows that the Genesio-Tesi system under consideration is able to exhibit complex and interesting behaviors including period doubling bifurcation, chaos, periodic windows and coexistence of multiple attractors. This latter phenomenon has not been found in previous studies of the Genesio-Tesi oscillator thus merits to be shared. We have also shown that Genesio-Tesi systems in their chaotic states can be synchronized and used for a possible masking of information, thus illustrating its importance in engineering. Numerical findings have been validated through experimental studies.

Hyperfine Intrinsic Magnitude and Phase Response Measurement of Optical Filters Based on Electro-Optical Harmonics Heterodyne and Wiener–Lee Transformation

An electro-optical heterodyne scheme is proposed and demonstrated for magnitude- and phase-frequency response measurement of optical filters based on harmonics heterodyne and Wiener–Lee transformation. The method consists of an acousto-optic frequency shifter and a phase modulator located in a frequency-shifted heterodyne interferometer. The minimum phase-frequency response is simultaneously extracted from the measured magnitude–frequency response with the help of Kramers–Kronig relations and the Wiener–Lee transformation. As compared with the single-sideband-based or double-sideband-based methods, our method eliminates small-signal assumption and features an immunity to undesired spurious sidebands, enabling harmonic sideband sweeping with even-folded measuring frequency range. Prior to the conventional frequency-shifted heterodyne methods, the method enables simultaneous extraction of intrinsic magnitude and phase frequency responses for most optical filters by introducing the Wiener–Lee transformation. A phase-shifted fiber Bragg grating is measured for extracting the frequency responses in the proof-of-concept experiment with the frequency resolution up to 50 kHz and frequency range of 80 GHz by using a frequency-swept modulation of 20 GHz.

Accuracy Estimation of a Correlation Interferometric Direction-Finder

Using theoretical research and numerical modeling, the parameters of the antenna array of the correlation interferometric direction-finder and its feeder arrangement are revealed in such a way that they can satisfy the required accuracy and the minimal hardware cost. It is shown by theoretical analysis and modeling that non-identical phase frequency responses of the analog receivers used in the direction-finder synthesized by the correlation interferometric approach do not affect the accuracy of the angular estimation.

Разработка математической модели и анализ особенностей режимов индуктивно-емкостного преобразователя на основе каткона

The article discusses matters concerned with developing the mathematical model of an inductive-capacitive converter (ICC) based on a coil-capacitor (katkon) — a new element of electrical circuits. The ICC mathematical model, which is based on the one-port active network (Thevenin’s) theorem, is constructed proceeding from the device equivalent circuit in the form of a nonlinear circuit with distributed parameters. An expression involving hyperbolic functions is obtained for determining the no-load voltage for the first boundary condition (with the output terminals opened) and the input impedance for the second boundary condition (with the output terminals closed) with respect to the device output terminals. To simplify the obtained expressions, the smallness of the parameters is estimated. A correlation between the device open-circuit voltage, power supply voltage, and the oscillatory circuit quality factor is established. It is shown that a katkon-based ICC can be used not only as a harmonic filtering and reactive power compensation device, but also as a step-up transformer. Expressions for finding the ICC input impedances and resonance frequencies for the first and second boundary conditions are obtained, and it is demonstrated that the resonance frequencies for both the boundary conditions almost coincide with each other. The calculated and experimental values of the open-circuit voltage, input impedances, and resonance frequencies are compared, and the adequacy of the proposed mathematical model is confirmed. The device physical model’s equivalent parameters are presented, and the model operation principle is analyzed. The amplitude-frequency and phase-frequency responses, and the load current and active power dependencies on the ICC physical model load resistance are constructed. The experimental and analytical characteristics and dependencies are compared; the mathematical model’s accuracy is evaluated, and the correctness of the model is confirmed. It is demonstrated that a katkon can be effectively used in current-limiting devices.