Measurement Of Phase Shift Research Articles

Identification of gyroscopic forces in the oscillatory system of a Coriolis flowmeter

The phase difference between the oscillations of the Coriolis flowmeter (CFM) arms is the main experimentally observed parameter during measurements of liquid flow rates in pipelines. Usually, steady-state oscillations and known dependences between the flow rate and the measured phase shift are assumed. However, these conditions are met with a sufficient accuracy only for homogeneous and single-phase flows. For inhomogeneous and multiphase flows, the correction of measurements is necessary. This correction in most cases is empirical. However, to improve the methodology of Coriolis flowmeter measurements, more detailed information about flow-tube interactions is needed. The experimental obtaining of such data is expensive and laborious. On the other hand, this data can be acquired during numerical experiments on the CFM virtual prototype. However, to effectively simulate liquid flows, it is necessary to separate the contribution of gyroscopic and dissipative forces to the experimentally observed signal (phase shift). This problem is complicated by the fact that gyroscopic forces are not uniformly distributed along the length of the tube, and the model for dissipative forces is not sufficiently developed yet. In this work, gyroscopic forces were separated by the 3D finite element modeling of steady-state oscillations of a tube with the ideal (inviscid) liquid. We discussed the usage of the simulation results in a simplified discrete model. It is shown that the magnitude of the phase shift recorded by the flowmeter depends both on the features of the distribution of gyroscopic forces and on the elastic coupling of the natural vibrations of the elastic tube caused by the fluid flow. The influence of the tube shape on the experimentally observed phase shift was investigated. For the tube shapes considered in the work, the difference in the phase shift for the displacements of the sections of the installation of the recording coils reaches nearly 5 times. The parameters of both gyroscopic and elastic coupling depend on the shape of the tube, and a change in the shape of the tube can increase the gyroscopic coupling and decrease the elastic one, and vice versa. The creation of a simplified discrete model of the flowmeter based on the results of the 3D finite element calculations is discussed. The quantitative estimates of the integral parameters of the oscillatory system of the CFM are carried out, allowing one to compare both the magnitude of the gyroscopic forces arising during the flow of the liquid and the degree of conformity of the tube shape to the special requirements for the oscillatory system of the CFM.

Application of spectral analysis for determine the phase shift of signals with equal amplitudes using full-wave transformation when measuring the characteristics of weapons

The article defines the list of technical characteristics of armaments and military equipment (ARM), the value of which is measured using phase methods. An analysis of known methods that have found wide application in measuring technology, which is designed to determine the technical characteristics associated with the measurement of phase shift during the development, manufacture and operation of weapons. Based on this analysis, it was determined that the measuring systems are designed to determine the phase shift of two harmonic signals in their composition have two channels of information transmission. This architecture of the implementation of measuring systems leads to the fact that a significant impact on the accuracy of the proposed measurement problem, makes a component of the error due to the phase symmetry of the signal transmission channels, as well as internal and external noise. As an alternative approach to solving the measurement problem of determining the phase shift of two harmonic signals, which will significantly reduce the error component due to phase asymmetry of information transmission channels, it is proposed to use the signal obtained by summing harmonic signals after full-wave transformation followed by spectral analysis. In order to implement the above approach, a measurement problem was set to determine the phase shift of two harmonic signals, using spectral analysis of the signal obtained by summing the harmonic signals after their full-wave transformation. A list of assumptions required for the synthesis of analytical relations that establish the relationship between the spectra of phases and amplitudes (power) of the signal obtained by summing harmonic signals after their full-wave transformation and phase shift of two harmonic signals. Analytical relationships are proposed that establish the relationship between the above characteristics. It is shown that the values of the spectrum of phases and amplitudes, which are calculated using the proposed expressions, differ from the values obtained in the calculations using the Fourier series coefficients, not more than 0.1%.

Real-Time Double-Layer Thin Film Thickness Measurements Using Modified Sagnac Interferometer with Polarization Phase Shifting Approach

This paper describes a modified Sagnac interferometer with a self-referenced polarization and phase-shifting technique for real-time thickness measurement of single- and double-layer transparent thin films. The proposed interferometric setup generated outstanding rotating linearly polarized light with a degree of polarization (DOP) of 99.40%. A beam splitter placed at the interferometer output separated the beam into two identical linearly polarized beams. One of the beams served as a reference, while the other served as a sensing arm. The output linear polarizer set at 45° relative to a reference plane was positioned anterior to the photodetectors to get rotating light intensities for phase shift measurement; hence, the intensities at various polarizations of 0°, 45°, and 90° were automatically acquired without any polarizing device adjustments. These intensities were then transformed into a phase retardation introduced by a sample, and the resulting phase shift was eventually converted into film thickness. The samples were properly prepared, with pure BK7 substrate being deposited by WO3-, Ta2O5-, and WO3/Ta2O5 films of known thicknesses. The thickness measurement obtained from the proposed system yielded reading errors of 1.3%, 0.2%, and 1.3/2.5% for WO3-, Ta2O5-, and WO3/Ta2O5 films, respectively. The mathematical theory was effectively demonstrated and empirically confirmed. The experimental results show that the proposed setup has a lot of potential for real-time, non-destructive thickness assessment of transparent thin films without the need to modify polarizing device orientations.

A constant-frequency ultrasonic phase method for monitoring imperfect adherent/adhesive interfaces

A primary mechanism of adhesive bond failure is a degradation of the adherent/adhesive interfacial stiffness from unwanted contamination or exposure to those environmental factors, which reduce adhesion quality. Substantial research has been conducted on the assessment of adhesively bonded structures and the detection of “kissing” bonds. Advanced ultrasonic assessment methods to interrogate bonded joints and measure interfacial stiffness using a distributed spring interface model have been developed. Amplitude-based ultrasonic methods have traditionally been used in adhesive bond quality assessment, but recent advancements in ultrasonic phase measurements allow for high measurement resolution with low-uncertainty. In this work, an ultrasonic phase technique for the monitoring of adhesively-bonded interfaces is demonstrated. Constant frequency measurements are obtained from the ultrasonic phase of the reflection coefficient from the adhesive bond with a glass adherent, where the degree of cure is controlled by exposure to ultraviolet light. A peak in the phase of the reflection coefficient, as predicted by the interfacial spring model, is measured experimentally. It is shown that the peak phase predicts the interfacial stiffness when some frequency dependent threshold value is crossed. With knowledge of the acoustic impedances of both materials at the interface, the interfacial stiffness is determined by an inverse algorithm involving measurements of ultrasonic phase shifts of bonded joint reflections. By monitoring the interface of bonded structures and coatings, this method permits a nondestructive inspection of bond strength from structural construction through its service life.

A new method for thermal conductivity measurement: application to complex heterogeneous materials used in thermal batteries

The thermal conductivity of heterogeneous materials used in thermal batteries is difficult to measure. These materials must be handled under controlled atmosphere with methods adapted to their porous nature. The method presented in this work uses heating plates to send a sinusoidal thermal signal to the tested sample. The whole setup is confined in a glovebox to ensure the composition and hygrometry of the atmosphere. Parametric computer simulations with varying thermal conductivity (λ) of the sample and thermal resistance (h) of the contacts as inputs were performed to calculate the phase shifts associated with two thicknesses of the sample. Experimental measurements of phase shifts on these two configurations allowed the identification of the only couple (λ,h) which matches the phase shifts on the respective thicknesses. This method is validated using the reference material BK7 at different temperatures. Thermal conductivities of a heterogeneous cathode used in thermal batteries is also given using this method.

Simulation of Single Channel Magnetic Induction Tomography for Meningitis Detection By Using COMSOL Multiphysics

Meningitis is a inflammation of the meninges and the most common central nervous system (CNS) due to bacterial infection. Numbers of children who have bacterial meningitis are still high in recent 15 years regardless of the availability of newer antibiotics and preventive strategies. This research focuses on simulation using COMSOL Multiphysics on the design and development of magnetic induction tomography (MIT) system that emphasizes on a single channel rotatable of brain tissue imaging. The purpose of this simulation is to test the capability of the developed MIT system in detecting the change in conductivity and to identify the suitable transmitter-receiver pair and the optimum frequency based on phase shift measurement technique for detecting the conductivity property distribution of brain tissues. The obtained result verified that the performance of the square coil with 12 number of turns (5Tx-12Rx) with 10MHz frequency has been identified as the suitable transmitter-receiver pair and the optimum frequency for detecting the conductivity property distribution of brain tissues.

A Low-Loss Silicon MEMS Phase Shifter Operating in the 550-GHz Band

This article presents a low-loss silicon microelectrical mechanical system (MEMS) phase shifter operating in the 500-600 GHz band. The phase shifter consists of a 30-μm thick perforated silicon slab that is moved in and out of a waveguide in the E-plane with a large deflection MEMS actuator. By implementing different hexagonal patterns in the silicon slab, a stepped permittivity is created to impedance match, and thus, reduce return loss. When the silicon slab is inserted into the waveguide, the phase velocity of the incoming wave is decreased, thus resulting in different phase shifts depending on the position of the slab inside the waveguide. The MEMS phase shifter is fully actuated at around 50 V and can move up to ±95 μm, depending on the applied voltage. The insertion loss, when the maximum phase shift is achieved, is measured to be 1.8 dB, compared to a 1.6-dB insertion loss for a waveguide of equivalent length. The return loss is better than 18 dB for the desired band. The measured phase shift, with the slab fully inserted into the waveguide at 550 GHz was 145 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">°</sup> . The MEMS phase shifter enables a variety of applications including phased array antenna systems with scanning capability for mapping of planetary surfaces with an electronically steerable antenna.

A flexible electrostatic nanogenerator and self-powered capacitive sensor based on electrospun polystyrene mats and graphene oxide films

Electrostatic nanogenerators or capacitive sensors that leverage electrostatic induction for power generation or sensing, has attracted significant interests due to their simple structure, ease of fabrication, and high device stability. However, in order for such devices to work, an additional power source or a post-charging process is necessary to activate the electrostatic effect. In this work, an electrostatic nanogenerator is fabricated using electrospun polystyrene (PS) mats and dip-coated graphene oxide (GO) films as the self-charged components. The electret performances of the PS mats and GO films are characterized via the electrostatic force microscopy phase shift and surface potential measurements. With a multilayer device structure that consists of top electrodes/GO films/spacer/electrospun PS mats/bottom electrodes, the resultant device acts as an electrostatic generator that operates in the noncontact mode. The nanogenerator can output a peak voltage of ca. 6.41 V and a peak current of ca. 6.57 nA at a rate of 1 Hz of mechanical compression, and with no attenuation of electrical outputs even after 50 000 cycles over a 13 h period. Furthermore, this as-prepared device is also capable of serving as a self-powered capacitive sensor for detection of tiny mechanical impacts and measurement of human finger bending. This results of this work provides a new avenue to easily fabricate electrostatic nanogenerators with high durability and self-powered capacitive sensors for the detection of small impacts.

Magnetic detection of high mechanical stress in iron-based materials using eddy currents and phase shift measurements

We present a non-invasive method of detecting stress below the elastic limit in magnetic steel elements. The method, based on well-known magnetoelastic effects, relies on mechanical stress-induced permeability modulation. It does not measure absolute values and hence results in suitable in situ measurements in situations where small position or vibration changes can change absolute values.

Spectral domain Z-scan technique

Characterizing the nonlinear optical properties of various materials plays a prerequisite role in nonlinear optics. Among different measurement methods, the well-known Z-scan technique and the modified versions have been recognized as simple and accurate methods for measuring both the real and imaginary parts of the nonlinear refractive index. However, the Z-scan methods based on detecting small beam variations impose a severe restriction on the roughness of materials. Therefore, measuring nonlinear optical properties of highly scattering media still remain challenging. Inspired by the innovation of the conventional Z-scan method that replaces the measurement of the wavefront phase shift by measuring the spatial pattern in the far-field, the spectral domain Z-scan technique is presented in this paper. It has the great potential in characterizing the nonlinear refractive index of highly scattering medium, since the scattering efficiency is insensitive to the wavelength for Mie scattering, which occurs for wavelengths far smaller than the roughness. Moreover, to demonstrate the advantages of the spectral domain Z-scan technique, the nonlinear refractions of polished slides and frosted slides were measured, which agree well with previous reports.

Vibration insensitive THz wave interferometry for characterizing optical phase shifter

Optic interferometry is a well-known measurement technique with high precision attained through the optical interference caused by the superposition of lightwaves. However, with fiber-optic interferometry, the phases of the lightwaves are susceptible to interference via the fiber fluctuation that is unavoidably induced by the environmental vibration, which makes the measurement result unstable and limits the usage scenarios of the interferometric installation. In this paper, a fiber-optic THz wave interferometer aiming for vibration isolation is presented. Due to the longer wavelength of the THz wave, the influence of optical fiber fluctuation on the phase noise is considerably suppressed. For verifying the feasibility of the fiber-optic THz wave interferometer, it is used here to measure the optical phase shift at a fiber-pigtailed thermo-optic phase shifter. The experimental results show that, compared with an all-fiber interferometer, the fiber-optic THz interferometer enables accurate measurement of an optical phase shift as well as an improved signal-to-noise ratio of interference with 6dB gain.

Directional phase-unwrapping algorithm and phase shift technique on hydrogel.

Refractive index microstructures, which can be written by multiphoton absorption with femtosecond lasers, have many applications. Here we present a directional phase-unwrapping algorithm with phase-shifting technique and apply it to the metrology of hydrogel microstructures. A staircase phase-unwrapping algorithm is demonstrated. This fast quality-guided path phase-unwrapping applies well to situations that are geometrically well defined and is quite tolerant of phase noise. To achieve precise very small phase shifts, we also present a slant angle technique on a DC servo stage along with phase shift measurement, allowing us to achieve 6.5 nm step sizes.

Numerical comparison of time-, frequency- and wavelet-domain methods for coda wave interferometry

SUMMARYTemporal changes in subsurface properties, such as seismic wave speeds, can be monitored by measuring phase shifts in the coda of two seismic waveforms that share a similar source–receiver path but that are recorded at different times. These nearly identical seismic waveforms are usually obtained either from repeated earthquake waveforms or from repeated ambient noise cross-correlations. The five algorithms that are the most popular to measure phase shifts in the coda waves are the windowed cross correlation (WCC), trace stretching (TS), dynamic time warping (DTW), moving window cross spectrum (MWCS) and wavelet cross spectrum (WCS). The seismic wave speed perturbation is then obtained from the linear regression of phase shifts with their respective lag times under the assumption that the velocity perturbation is homogeneous between (virtual or active) source and receiver. We categorize these methods into the time domain (WCC, TS, DTW), frequency domain (MWCS) and wavelet domain (WCS). This study complements this suite of algorithms with two additional wavelet-domain methods, which we call wavelet transform stretching (WTS) and wavelet transform DTW, wherein we apply traditional stretching and DTW techniques to the wavelet transform. This work aims to verify, validate, and test the accuracy and performance of all methods by performing numerical experiments, in which the elastic wavefields are solved for in various 2-D heterogeneous half-space geometries. Through this work, we validate the assumption of a linear increase in phase shifts with respect to phase lags as a valid argument for fully homogeneous and laterally homogeneous velocity changes. Additionally, we investigate the sensitivity of coda waves at various seismic frequencies to the depth of the velocity perturbation. Overall, we conclude that seismic wavefields generated and recorded at the surface lose sensitivity rapidly with increasing depth of the velocity change for all source–receiver offsets. However, measurements made over a spectrum of seismic frequencies exhibit a pattern such that wavelet methods, and especially WTS, provide useful information to infer the depth of the velocity changes.

Influence of modified light-flavor hadron spectra on particle yields in the statistical hadronization model

Hadron production in relativistic nuclear collisions is well described in the framework of the Statistical Hadronization Model (SHM). We investigate the influence on SHM predictions of hadron mass spectra for light-flavor baryons and mesons modified by the addition of about 500 new states as predicted by lattice QCD and a relativistic quark model. The deterioration of the resulting thermodynamic fit quality obtained for Pb–Pb collision data at sNN=2.76 TeV suggests that the additional states are not suited to be naively used since also interactions among the states as well as non-resonant contributions need to be considered in the SHM approach. Incorporating these effects via the pion nucleon interaction determined from measured phase shifts leads again to excellent reproduction of the experimental data. This is a strong indication that at least the additional nucleon excited states cannot be understood and used as independent resonances.

Adapted Fringe Projection Sequences for Changing Illumination Conditions on the Example of Measuring a Wrought-Hot Object Influenced by Forced Cooling

Optical 3D geometry reconstruction, or more specific, fringe projection profilometry, is a state-of-the-art technique for the measurement of the shape of objects in confined spaces or under rough environmental conditions, e.g., while inspecting a wrought-hot specimen after a forging operation. While the contact-less method enables the measurement of such an object, the results are influenced by the light deflection effect occurring due to the inhomogeneous refractive index field induced by the hot air around the measurand. However, the developed active compensation methods to fight this issue exhibits a major drawback, namely an additional cooling of the object and a subsequent transient illumination component. In this paper, we investigate the cooling and its effect on temporal phase reconstruction algorithms and take a theoretical approach to its compensation. The simulated compensation measures are transferred to a fringe projection profilometry setup and are evaluated using established and newly developed methods. The results show a significant improvement when measuring specimens under a transient illumination and are easily transferable to any kind of multi-frequency phase-shift measurement.Dataset License: CC-BY

Method for the differential measurement of phase shifts induced by atoms in an optical ring cavity

We demonstrate a new method of light phase shift measurement using a high-finesse optical ring cavity which exhibits reduced phase noise due to cavity length fluctuations. Two laser beams with a frequency difference of one cavity free spectral range are simultaneously resonant with the cavity, demonstrating noise correlations in the error signals due to the common-mode cavity length fluctuations. The differential error signal shows a 30 dB reduction in cavity noise down to the noise floor in a frequency range up to half the cavity linewidth ($\delta\nu/2 \simeq 30$ kHz). Various noise sources are analyzed and their contributions to the noise floor are evaluated. Additionally, we apply this noise-reduced phase shift measurement scheme in a simulated spin-squeezing experiment where we have achieved a factor of 40 improvement in phase sensitivity with a phase resolution of 0.7 mrad, which may remove one important barrier against attaining highly spin-squeezed states. The demonstrated method is the first reported measurement using an optical ring cavity and two independent beams, a flexible situation. This method can find direct application to non-destructive measurements in quantum systems, such as for the generation of spin-squeezed states in atom interferometers and atomic clocks.

Optoelectromechanical phase shifter with low insertion loss and a 13π tuning range.

We present an on-chip optoectromechanical phase shifter with low insertion loss and low half-wave voltage using a silicon nitride platform. The device is based on a slot waveguide in which the electrostatic displacement of mechanical structures results in a change of the effective refractive index. We achieve insertion loss below 0.5 dB at a wavelength of 1550 nm in a Mach-Zehnder Interferometer with an extinction ratio of 31 dB. With a phase tuning length of 210 µm, we demonstrate a half-wave voltage of Vπ = 2.0 V and a 2π phase shift at V2π = 2.7 V. We measure phase shifts up to 13.3 π at 17 V. Our devices can be operated in the MHz range and allow for the generation of sub-µs pulses.

An original determination of the maximum phase shift range obtained for an array of N coupled oscillators

This paper presents an original approach, using a harmonic balance optimization method, allowing to predict the maximum phase shift range that can be practically obtained for an array of N coupled oscillators. Indeed, unlike what is predicted by the theory, the proposed analysis allows to show that the maximum value of the phase shift decreases by increasing the number N of coupled oscillators in the array. Hence, this method allows to find an empirical limit of the phase shift obtained between two adjacent oscillators which tends to ± 180°/N. The results obtained with the proposed method are compared with the measurement results of an array made of two and four coupled voltage controlled oscillators (VCOs) implemented in the QUBiC4X 0.25 µm BiCMOS SiGe:C process of NXP semiconductors. These measurement results confirmed that the maximum measured phase shift range is close to ± 180°/2 and ± 180°/4 for arrays made of two and four coupled VCOs respectively.

Phase Shift and Amplitude Array Measurement System Based on 360° Switched Dual Multiplier Phase Detector

This article presents an amplitude and 360° phase shift array measurement system. The basic cell of the measurement system uses a novel amplitude and phase detector based on switched dual multipliers. The phase shift measurement is characterized using an analog phase detector (mixer), detecting a maximum range of ±90°, and a double multiplication of the input signals, in phase and phase shifted. This method broadens the frequency and amplitude range beyond other solutions that require fulfilling the quadrature condition. This method broadens the frequency and amplitude beyond other solutions requiring fulfilling the quadrature condition or phase and amplitude balance. Thus, it enables to compensate significant phase imbalance in the 90° hybrid or use amplitudes out of the range that ensures the switching operation of mixer diodes. The circuit calibration that allows compensation for errors (amplitude, phase shift, mismatching, etc.) is detailed, and its relation to the required measurement accuracy is discussed. The design can be easily extrapolated to other frequency ranges because it uses commercial RF devices available in a wide frequency range and avoids the need of crossing lines or complex 90° hybrid. A prototype with $3 \times 3$ cells has been built to evaluate various test conditions on $1 \times 3$ cell configurations that show the advantages of the procedure. It should be highlighted that the cell prototype uses devices that will be operating outside the frequency and amplitude ranges recommended by their manufacturers. A calibration from 2.6 to 6 GHz and −15 to −3 dBm was performed to evaluate the measurement errors. An analysis of the isolation between cells and different calibration configurations is performed to analyze the measurement errors. Measurements show compensation of +30°/−25° phase imbalance and 13-dB power lower than mixer manufacturer recommendation.

Technique for dynamic error compensation of the displacement measurement method by measuring transducer of inductosin type, based on phase shift measurement

Датчики типу індуктосин широко застосовуються для вимірювання переміщення в різних технічних і технологічних галузях. Вони відзначаються надійністю, довговічністю, низькою статичною похибкою вимірювання, простотою обслуговування. Нині в експлуатації знаходиться значна кількість обладнання, в якому використовуються вимірювачі переміщення на основі датчиків типу індуктосин. Одним із методів вимірювання переміщення з використанням індуктосинів є метод, що базується на перетворенні кутового переміщення в фазу, істотним недоліком якого є наявність динамічної похибки методу вимірювання. Таким чином, завдання компенсації динамічної похибки методу вимірювання переміщення за допомогою вимірювального перетворювача типу індуктосин, що базується на вимірюванні зсуву фази, є актуальним і становить певний науковий і практичний інтерес. У статті розглянуто спосіб компенсації динамічної похибки методу вимірювання переміщення за допомогою вимірювального перетворювача типу індуктосин, що базується на вимірюванні зсуву фази, який не потребує застосування додаткових приладів для визначення швидкості переміщення заготовки, наприклад тахогенераторів. Для визначення швидкості переміщення заготовки пропонується використовувати дані, отримані при вимірюванні переміщення за допомогою вимірювального перетворювача типу індуктосин із застосуванням методу вимірювання, що базується на вимірюванні зсуву фази. Відзначено, що запропоноване рішення дасть можливість повністю компенсувати абсолютну динамічну похибку розглянутого методу вимірювання переміщення тільки для випадків рівномірного або рівноприскореного руху. В реальності характер руху виконавчого органу визначається роботою конкретного типу електроприводу і його складових частин, а саме системи управління, електродвигуна, а також характеристиками технологічного обладнання. У загальному випадку для визначення впливу обладнання на абсолютну динамічну похибку необхідно проводити статистичні дослідження для конкретного типу електроприводу і техноло-гічного обладнання. Для реалізації розглянутого способу компенсації динамічної похибки запропоновано модернізовану структуру мікроконтролерного вимірювача переміщення з використанням індуктосину як датчика положення. Застосування методу компенсації динамічної похибки дасть змогу істотно розширити експлуатаційні характеристики методу вимірювання, а саме – підвищити точність вимірювання, й істотно збільшити максимальне значення швидкості переміщення заготовки.