Measurements Of Field Research Articles

Unconventional quantum oscillations and evidence of nonparabolic electronic states in quasi-two-dimensional electron system at complex oxide interfaces

The simultaneous occurrence of electric-field controlled superconductivity and spin-orbit interaction makes two-dimensional electron systems (2DES) constructed from perovskite transition metal oxides promising candidates for the next generation of spintronics and quantum computing. It is, however, essential to understand the electronic bands thoroughly and verify the predicted electronic states experimentally in these 2DES to advance technological applications. Here, we present insights into the electronic states of the 2DES at oxide interfaces through comprehensive investigations of Shubnikov–de Haas oscillations in three different systems: EuO/KTaO3, LaAlO3/SrTiO3, and amorphous-LaAlO3/KTaO3. To accurately resolve these oscillations, we conducted transport measurements in high magnetic fields up to 60 T and low temperatures down to 100 mK. For 2D confined electrons at these interfaces, we observed a progressive increase of oscillations frequency and cyclotron mass with the magnetic field. We interpret these universal and intriguing findings by considering the existence of nontrivial electronic bands, for which the E−k dispersion incorporates both linear and parabolic relations. In addition to providing experimental evidence for nonparabolic electronic states in KTaO3 and SrTiO3 2DES, the unconventional oscillations presented in this study establish a paradigm for quantum oscillations in 2DES based on perovskite transition metal oxides, where the oscillation frequencies in 1/B exhibit quadratic dependence on the magnetic field. Published by the American Physical Society 2024

A data processing method for two-Color pyrometers in accurate temperature measurement of high-temperature flow fields

A data processing method for two-Color pyrometers in accurate temperature measurement of high-temperature flow fields

Measuring anisotropy field of patterned soft magnetic films by anisotropic ferromagnetic resonances.

Patterned magnetic films have been applied widely in communication technology for meeting the development of miniaturization and high frequency. However, there has been some debate about the measuring of the anisotropy field, which is significant for deciding the electromagnetic performance. In the paper, we proposed the measurement of the anisotropy field using anisotropic ferromagnetic resonances in patterned permalloy magnetic films. The anisotropy in patterned permalloy with different magnetic stripe widths can be observed qualitatively by the hysteresis loop along in-plane x and y directions, which induces the anisotropic ferromagnetic resonant behaviors. The anisotropy field can be calculated quantificationally by fitting the Kittel equation when the single resonant peak appears under applied magnetic fields. The values of the anisotropy field obtained by anisotropic ferromagnetic resonances are on the lower side to compare with the ones obtained by the energy difference between easy anis and hard axis. Our results can provide an extra method for measuring the anisotropy field, which can be useful for designing electromagnetic devices and potential applications in next-generation wireless communication.

Utilizing the Gravity Method to Detect the Potential Effect of the Salt Dome in the Nahr Omar Oilfield, Southern Iraq

Geophysics is one of the branches of Earth sciences and deals with studying the Earth's interior by studying the variation of physical properties within rock layers. Applied geophysics depends on procedures that involve the measurements of potential fields, such as the gravitational method. One of the significant oil fields in southern Iraq is represented by the Nahr Omar structure. A power spectrum analysis (SPA) technique was used to collect gravity data within the chosen oil field area in order to confirm the salt dome in the subsurface layers. The analysis of SPA resulted from six surfaces representing the gravity variation values of the depths (m)14300, 3780, 3290, 2170, 810, and 93.5. Gravity surfaces have been converted to density surfaces to determine density and velocity models from these six depth slices. The inverted data were consistent with the Nafe and Drake standard curves of converting densities to average velocities. The current study illustrated the benefit/assist of the inversion technique of gravity data to average velocity, to a large extent, in detecting the salt dome effects on the subsurface strata for the Nahr Omar oilfield. In comparison, the decrease in the average velocity of the salt dome area is related to this effect. The acquired inversion results were supported by available seismic data within the Nahr Omar area and utilized the seismic attributes processing technique.

Experimental measurement of electric field near the insulator string

This paper explores the electric field distribution near a string of six NJ120 high voltage insulators through experimental measurements under various conditions. Using a distributed capacitance method with custom probes connected to an Arduino-based system, tests were conducted on clean and polluted insulators. Pollution was simulated using a tuf-based solution with conductivities ranging from 0.5 to 1.97 mS/cm. Measurements were taken at 13 heights and four distances (1 to1.75 m) under applied AC voltages of 15 to 80 kV. The study also investigates the effects of damaged insulators, placed at different positions (near the high voltage terminal, in the middle, and near the ground), as well as the role of guard rings in improving field uniformity. Results indicate that pollution and damaged insulators significantly increased field intensity, particularly near the high voltage terminal. Guard rings effectively reduced field peaks, with larger radii and optimal placement providing the best performance. These findings contribute to optimizing high voltage insulator design for enhanced reliability.

A spin-refrigerated cavity quantum electrodynamic sensor

Quantum sensors based on solid-state defects, in particular nitrogen-vacancy (NV) centers in diamond, enable precise measurement of magnetic fields, temperature, rotation, and electric fields. Cavity quantum electrodynamic (cQED) readout, in which an NV ensemble is hybridized with a microwave mode, can overcome limitations in optical spin detection and has resulted in leading magnetic sensitivities at the pT-level. This approach, however, remains far from the intrinsic spin-projection noise limit due to thermal Johnson-Nyquist noise and spin saturation effects. Here we tackle these challenges by combining recently demonstrated spin refrigeration techniques with comprehensive nonlinear modeling of the cQED sensor operation. We demonstrate that the optically-polarized NV ensemble simultaneously provides magnetic sensitivity and acts as a heat sink for the deleterious thermal microwave noise background, even when actively probed by a microwave field. Optimizing the NV-cQED system, we demonstrate a broadband sensitivity of 576 ± 6 fT/Hz\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\sqrt{{{{\\rm{Hz}}}}}$$\\end{document} around 15 kHz in ambient conditions. We then discuss the implications of this approach for the design of future magnetometers, including near-projection-limited devices approaching 3 fT/Hz\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\sqrt{{{{\\rm{Hz}}}}}$$\\end{document} sensitivity enabled by spin refrigeration.

Measurements of the solar coronal magnetic field based on coronal seismology with propagating Alfvénic waves: forward modeling

Abstract Recent observations have demonstrated the capability of mapping the solar coronal magnetic field using the technique of coronal seismology based on the ubiquitous propagating Alfv'{e}nic/kink waves through imaging spectroscopy. We established a magnetohydrodynamic (MHD) model of a gravitationally stratified open magnetic flux tube, exciting kink waves propagating upwards along the tube. Forward modeling was performed to synthesize the Fe \textsc{xiii} 1074.7 and 1079.8 nm spectral line profiles, which were then used to determine the wave phase speed, plasma density, and magnetic field with seismology method. A comparison between the seismologically inferred results and the corresponding input values verifies the reliability of the seismology method. In addition, we also identified some factors that could lead to errors during magnetic field measurements. Our results may serve as a valuable reference for current and future coronal magnetic field measurements based on observations of propagating kink waves.

Optimization of Electron Beams for Ion Bombardment Secondary Emission Electron Gun

Abstract Electron beam fluorescence technology is an advanced non-contact measurement in rarefied flow fields, the fluorescence signal intensity is positively correlated with the electron beam current. The ion bombardment secondary emission electron gun is suitable for the technology. To enhance the beam current, COMSOL simulations and analyses were con-ducted to examine plasma density distribution in the discharge chamber under the effects of various conditions and the electric field distribution between the cathode and the spacer gap. The anode shape and discharge pressure conditions were optimized to increase plasma density. Additionally, an improved spacer structure was designed with the dual purpose of enhancing the electric field distribution between the cathode-spacer gap and improving vacuum dif-ferential effects. This design modification aims to increase the pass rate of secondary elec-trons. Both simulation and experimental results demonstrated that the performance of the optimized electron gun was effectively enhanced. When the electrode voltage remains con-stant and the discharge gas pressure is adjusted to around 8 Pa, the maximum beam current was increased from 0.9mA to 1.6 mA.

Magnetic Field Sensor Using the Magnetic Fluid-Encapsulated Long-Period Fiber Grating Inscribed in the Thin-Cladding Fiber

Optical magnetic field current sensors could overcome the shortcomings of traditional sensors based on electrical principles, such as large volume, insufficient sensitivity, and limitations of working environment, which can be applied to medical, military, and other fields with higher sensing requirements. We demonstrated experimentally the inscription of the long-period fiber gratings (LPFGs) in the thin-cladding fiber (TCF). The magnetic field current sensor is fabricated by encapsulating the TCF–LPFG with magnetic fluid (MF) nanoparticles. The principle of the sensor is based on the refractive index tunability of the MF with the magnetic field (current). The measurement of the external magnetic field (current) can be obtained by detecting the wavelength shift of the coated TCF–LPFG, which changes with the applied magnetic field. In the intensity range of 0 ∼ 11 mT, the experimental sensitivity of magnetic field measurement is up to −0.31 nm/mT. The proposed magnetic field current sensor has potential applications in practical measurement of magnetic field.

Turbulence distortion and blockage in the induction zone of a horizontal axis turbine

Wind tunnel measurements of the incident turbulent velocity fields and axial forces on a horizontal axis turbine and porous disc analogues are reported. The models were tested in both a simulated atmospheric boundary layer (ABL) and in grid turbulence, allowing for a range of turbulence length scale to rotor diameter ratios to be considered. A theoretical framework to account for the combined effect of distortion and potential flow blocking in the induction zone is presented. In the case of very large length-scale turbulence to diameter ratios, where distortion effects are minimal, a quasi-steady approach is adopted for the effect of blocking. For the small length-scale ratio limit, the method is developed from the classical analyses for rapid distortion of turbulence and blockage from flow through a porous sheet of resistance. For general length-scale ratios, an efficient prediction method based on interpolation between the two length-scale ratio extremes is established. For very large length-scale ratios, a quasi-steady theory without distortion is appropriate for a rotor or disc in a simulated ABL. The small length-scale theory is applicable for tests conducted in grid turbulence. The results of the study can inform the prediction and interpretation of typical measurements of turbulence within the induction zone and the fluctuating loads on a rotor, at both prototype and full scale. This is of particular importance to fatigue load assessments.

Experimental study of the couple effects of internal and external cooling on double-wall laminate structure with novel slot and pin-fins

This study investigates the couple effects of internal and external cooling on double-wall laminate cooling (DWLC) structure with novel impingement jet, pin-fins, and slot hole. The distribution of film cooling effectiveness (FCE) and heat transfer coefficient (HTC) were measured using transient liquid crystal (TLC) and pressure sensitive paint (PSP) methods. In order to improve the accuracy of TLC method, a thermal inertia correction method based on radial basis function neural network (RBFNN) was proposed. It was found that the pin-fins would significantly affect the external film cooling characteristics. There is a counter-rotating vortex pair at the downstream of the pin-fins inside the coolant film. This leads to a higher FCE at the downstream region of pin-fins and a lower FCE at the region between the pin-fins. The internal heat transfer is minimally influenced by slot height and inclination angle. Increasing filling ratio greatly reduces the area-averaged FCE and changes the flow field at slot outlet. The DWLC structure in this study shows excellent cooling performance and is currently mainly used in the field of aero-engines. However, it can also be applied to the cooling design of gas turbines, electronics, and other fields after scaling the size. Additionally, the improved TLC experimental method can be widely used in heat transfer measurement in the aforementioned research fields.

Four-Port Probe for Simultaneous Measurement of Electric and Magnetic Fields in Near-Field Scanning

Four-Port Probe for Simultaneous Measurement of Electric and Magnetic Fields in Near-Field Scanning

Abstract B033: Towards magnetic resonance microscopy for liquid biopsy in cancer therapy monitoring

Abstract The advancement of liquid biopsy techniques promises to revolutionize cancer diagnostics and therapy monitoring, by offering a minimally invasive approach to track tumor progression and treatment efficacy. One central issue preventing advancements are innovations in sensor technology, necessary to enable the detection of molecular and cellular biomarkers with sufficient precision. Over the past decade, atomic-scale quantum sensors have emerged as powerful detectors, offering the ability to perform precise measurements of temperature, pressure, and magnetic fields on the single cell scale. These sensors, based on the interaction of spin qubits with their environment, have the unique capability to amplify and exploit environmental interactions for highly accurate detection, making them ideal for complex biological applications. In this context, we present an advanced quantum sensing platform specifically tailored for liquid biopsy applications in cancer therapy monitoring. This platform integrates the capabilities of optical microscopy with magnetic resonance imaging (MRI) techniques, utilizing nitrogen-vacancy (NV) centers in diamond as quantum sensors by converting magnetic resonance signals into optical signals, which are subsequently captured by a high-speed camera. Our platform offers a novel approach, promising quantitative analysis of single cancer cells from liquid samples with unprecedented accuracy. Unlike traditional MRI, our method captures signals over a wide field of view directly in real space. Each camera pixel records a magnetic resonance spectrum, providing detailed multicomponent information about the sample, such as molecular concentration, diffusion, and relaxation behavior, which are critical for understanding the tumor’s microenvironment. Our quantum sensing technology holds significant potential for enhancing the sensitivity of liquid biopsies. By capturing detailed molecular information from blood or other body fluids, it will enable in-depth analysis of Circulating Tumor Cells (CTCs), circulating tumor DNA (ctDNA), exosomes, and other biomarkers. Citation Format: Karl D. Briegel, Robin D. Allert, Dominik B. Bucher, Julia D. Draeger, Nick R v. Grafenstein, Linyan Nie. Towards magnetic resonance microscopy for liquid biopsy in cancer therapy monitoring [abstract]. In: Proceedings of the AACR Special Conference: Liquid Biopsy: From Discovery to Clinical Implementation; 2024 Nov 13-16; San Diego, CA. Philadelphia (PA): AACR; Clin Cancer Res 2024;30(21_Suppl):Abstract nr B033.

Arbitrary Waveform Voltage Measuring Converter for Wideband AC Voltmeter

Alternating current (AС) voltage measurement is one of the most common types of measurements in various fields of science and technology. To evaluate the AC voltage level, special voltmeters are used which allow recording of amplitude, average and/or root mean square (RMS) voltage values. Among these measuring instruments, voltmeters of mean square voltage are especially significant because RMS is a fundamental physical characteristic of an electrical signal and is a true measure of power. The wide distribution of non-sinusoidal signals necessitates the creation of voltmeters for direct measurement of RMS. The main component of such voltmeter is an AC voltage to direct current (DC) voltage measuring converter based on the root-mean-square value level (AC RMS-DC converter). An analysis of existing technical solutions shows that it is advisable to use a thermoelectric converter (TEC) for high-precision measurement of RMS voltage of an arbitrary shape with a spectrum in the frequency band from 20 Hz to 20–50 MHz. Such a AC RMS-DC converter must contain a differential semiconductor TEC and an input broadband voltage amplifier with low nonlinearity of the frequency response. The aim of the paper was to develop a measuring AC RMS-DC converter of arbitrary shape voltage in which special attention is paid to modernization of the TEC and reduction of the AC RMS-DC converter error using corection of the frequency response of the input amplifier and introduction automatic calibration of the output voltage. Features of semiconductor chips and design of TEC in the form of a microcircuit or microassembly, results of converter’s and TEC elements’ parameters measurements are presented. A significant influence of the frequency response of the input amplifier and the offset voltage of the TEC transistors on the AC RMS-DC converter error was noted. Modernization of the input amplifier and introduction of automatic calibration of the output voltage ensured an error in a sinusoidal signal converting of less than 1 % in the range from 20 Hz to 50 MHz.

A uniqueness theory on determining the nonlinear energy potential in phase-field system

Abstract The phase-field system is a nonlinear model that has significant applications in material sciences. In this paper, we are concerned with the uniqueness of determining the nonlinear energy potential in a phase-field system consisting of Cahn–Hilliard and Allen–Cahn equations. This system finds widespread applications in the development of alloys engineered to withstand extreme temperatures and pressures. The goal is to reconstruct the nonlinear energy potential through the measurements of concentration fields. We establish the local well-posedness of the phase-field system based on the implicit function theorem in Banach spaces. Both of the uniqueness results for recovering time-independent and time-dependent energy potential functions are provided through the higher order linearization technique.

Optical manipulation of magnetic microspheres Enables high-sensitivity Fiber-optic magnetic field sensors

This study uses single-fiber optical tweezers to capture non-uniform magnetic particles, producing a novel type of magnetic field sensor for implementing the measurement of external magnetic field changes. A tapered fiber optic probe is used to capture magnetic particles as a sensing probe, constituting an Fabry–Pérot (F-P) interferometric structure. When an external magnetic field is applied, the magnetic particles at the tip of the optical fiber are deflected, affecting the length change of the interference cavity. By reconstructing the axial displacement of the particles, the accurate measurement of the magnetic field within the range of 1–10 mT is successfully realized with a sensitivity of 258 nm/mT. The minimum detectable intensity is 1.44 nT/Hz. This method offers a feasible and effective solution for the realization of magnetic field measurements by using the capture of non-uniform magnetic particles, which can play an important role in the fields of medicine and biology.

Theoretical and experimental study of diffraction by a thin cone

A problem of diffraction of ultrasound acoustic waves by an acute-angled hard cone is studied. Within the framework of the parabolic equation method, an analytical solution of the problem for an arbitrarily located point source is built. Specifically, the problem is reduced to the Volterra boundary integral equation, which can be solved using the Fourier transform. An experimental measurement of the diffracted field is carried out. The experiment is based on the MLS method adapted for narrowband sound sources. A comparison of experimental and theoretical results is provided.

Local measurement on oedometric compression tests: Time and temperature ageing effects on a fluorosilicone

O-ring durability is a key issue for engineering structures that require sealing over a long service life. Rubber-like materials are used for this type of component because of the assumption of incompressibility, i.e. a high bulk modulus K. However, this assumption has been called into question in the literature, particularly for elastomers under high hydrostatic pressures. This work examines the compressibility of rubber-like materials, with a particular focus on fluorosilicone elastomers (FVMQ). A method of confined compression using a transparent crucible is presented, which allows local measurement of the displacement field. This technique provides a better understanding of the analysis of oedometric compression data and a reliable way to determine the K value. Furthermore, this approach allows following the evolution of K over time with accelerated ageing. Three ageing temperatures - 200, 220 and 250 °C - were tested up to 34, 15 and 1 weeks respectively. For the three ageing temperatures, the FVMQ results show a decrease in K values with ageing. In particular, at 250 °C, a turning point was observed after 72 h of ageing. These results highlight the influence of ageing on the compressibility of the FVMQ and the presence of two different ageing mechanisms affecting the K evolution.

Dual-biomimetic curved compound-eye camera system for multi-target distance measurement in a large field of view.

Biomimetic curved compound-eye cameras (BCCECs) have attracted great attention for their potential applications in a variety of fields such as target recognition, monitor and three-dimensional localization in military due to their unique optical properties such as large field of view (FOV) and small size. In this work, we proposed a multi-target distance measurement method based on a dual-BCCEC system in a large FOV. To guarantee the precise measurement of the distance of multiple targets, a feature point searching and matching algorithm is developed for the dual-BCCEC system to improve the localizing efficiency of common feature points. In addition, a CALibration Tag (CALTag) self-recognition calibration method is also developed to calibrate ommatidia of the BCCEC with a high efficiency. Based on these two methods, the coordinates of multiple targets with clear feature points can be obtained after the distortion correction in sub-images and thus the distances of multiple targets with clear feature points can be achieved simultaneously with a single compound-eye raw image. The experiment results show that the dual-BCCEC system has a high distant measurement accuracy with an error of less than 6.80% for at least ten different targets in the a working distance ranging from 400 to 600 m in a quite large FOV of 98°×98°. The method demonstrated in this work can pave the way for multi-targets tracking in those related areas with high security monitoring requirements.

On the disruption of the horseshoe vortex in flow past bed-mounted cylinders

The present study investigates the disruption of the horseshoe vortex (HSV) formed around a bed-mounted circular cylinder using helical strakes. Three cylinders were studied: one plain and two with helical strakes, oriented at 30° and 0° to the vertical mid-plane, respectively. A planar particle image velocimeter (PIV) technique was employed for the measurement of the velocity field near the upstream bed-cylinder junction. The results revealed that strakes oriented at 0° prevent the formation of the HSV by disrupting the downward flow near the cylinder-bed junction. In contrast, a strong downflow was observed near the bed for the plain and 30° straked cylinder. The 0° helical strakes can be potentially used as scour-countermeasure around the pier due to their ability to disrupt the HSV. Analysis of turbulent stresses further demonstrated that the 0° straked cylinder experienced a reduction in Reynolds shear stress compared to both the plain and 30° straked cylinder.