Calibration Setup Research Articles

The Application of Supervised Machine Learning Algorithms for Image Alignment in Multi-Channel Imaging Systems.

This study presents a method for aligning the geometric parameters of images in multi-channel imaging systems based on the application of pre-processing methods, machine learning algorithms, and a calibration setup using an array of orderly markers at the nodes of an imaginary grid. According to the proposed method, one channel of the system is used as a reference. The images from the calibration setup in each channel determine the coordinates of the markers, and the displacements of the marker centers in the system's channels relative to the coordinates of the centers in the reference channel are then determined. Correction models are obtained as multiple polynomial regression models based on these displacements. These correction models align the geometric parameters of the images in the system channels before they are used in the calculations. The models are derived once, allowing for geometric calibration of the imaging system. The developed method is applied to align the images in the channels of a module of a multispectral imaging polarimeter. As a result, the standard image alignment error in the polarimeter channels is reduced from 4.8 to 0.5 pixels.

Design and Uncertainty Evaluation of a Calibration Setup for Turbine Blades Vibration Measurement.

Turbomachinery engines face significant failure risks due to the combination of thermal loads and high-amplitude vibrations in turbine and compressor blades. Accurate stress distribution measurements are critical for enhancing the performance and safety of these systems. Blade tip timing (BTT) has emerged as an advanced alternative to traditional measurement methods, capturing blade dynamics by detecting deviations in blade tip arrival times through sensors mounted on the stator casing. This research focuses on developing an analytical model to quantify the uncertainty budget involved in designing a calibration setup for BTT systems, ensuring targeted performance levels. Unlike existing approaches, the proposed model integrates both operational variability and sensor performance characteristics, providing a comprehensive framework for uncertainty quantification. The model incorporates various operating and measurement scenarios to create an accurate and reliable calibration tool for BTT systems. In the broader context, this advancement supports the use of BTT for qualification processes, ultimately extending the lifespan of turbomachinery through condition-based maintenance. This approach enhances performance validation and monitoring in power plants and aircraft engines, contributing to safer and more efficient operations.

Quantifying the Effects of Wind Turbulence on CO2 Flux Measurement in a Closed Chamber

This study aimed to investigate the effects of wind turbulence on CO2 transport within a medium and the extent of measurement errors in a closed chamber. Therefore, in a laboratory with controllable environmental conditions, the measurement performance of the closed chamber at various wind speeds was assessed using a soil respiration calibration apparatus and four types of porous media. The experimental results indicated that the closed chamber under the influence of wind turbulence exhibited varying degrees of underestimation, ranging from −51 to −6%. The effects of wind turbulence were more pronounced in sandy soils. As wind turbulence enhanced gas transport within the medium, the flux measurements of the closed chamber were biased, and this phenomenon was closely related to the medium’s particle size and surface wind speed. To address this issue, it is recommended to conduct long-term monitoring and eliminate errors by averaging repeated measurements, which will improve the accuracy of the ecosystem carbon budget.

Design of a high accuracy wideband current sensing system by tunneling magnetoresistive device with digital parametric equalizer

Wideband current sensors play a crucial role in the future power grid, especially with the increasing integration of renewable energy and nonlinear loads. This research developed a sensor configuration using tunneling magnetoresistive (TMR) devices for wideband current measurement. A parametric equalizer was also introduced to compensate for minor fluctuations in the TMR sensor's frequency response, thereby reducing wideband measurement errors. A calibration setup was created to test the frequency-dependent accuracy of the compensated TMR sensor. Results showed that relative errors in wideband measurements were reduced to 2 % after compensation, compared to 6 % of the uncompensated results, with power frequency measurement errors falling below 1 %. Furthermore, the designed TMR sensors were deployed in a 0.4 kV household district, demonstrating their practical application in diagnosing the spectral content of the load current. The analysis revealed a range of wideband components, including low-frequency components below 50 Hz, intermediate harmonics, and supraharmonics.

Comprehensive calibration of omnidirectional mirror and catadioptric optical system dedicated to high-speed video registration of lightning

The paper presents calibration setup and method dedicated to almost all types of omnidirectional mirrors such as hyperbolic and elliptic as well as including those with analytically or even numerically defined curvature. At its initial stage the calibration procedure use a pinhole and fisheye camera calibration algorithms to estimate and remove optical distortions introduced to catadioptric system by the image recorder and lens. The next stage allows to calculate the projection characteristics of the mirror and complex matrix of image deformation which can be further used for a low-cost image correction. Calibration procedure was verified using mirror prototypes manufactured with application of CNC milling machines and Physical Vapor Deposition technique. Three mirrors with 15°, 30° and 45° top view angles were tested. Projection characteristics were evaluated for a set of wide range cloud-to-ground lightning video registrations. Proposed method can be implemented to improve quality of omnidirectional observation and photogrammetry.

Research on calibration method for flange-type apparatus to Measure Water Permeability of Concrete

Abstract The water permeability of concrete is a crucial indicator to evaluate its ability to resist the infiltration of water or other liquids under pressure, which is vital for ensuring the stability and durability of building structures. The flange-type apparatuses are commonly used for detecting concrete’s impermeability and determining its impermeability rating. This article proposes a novel calibration method specifically designed for the flange-type apparatus to measure the water permeability of concrete, according to which the standard pressure measuring device is connected to the calibrated apparatus by a connection device designed and presented in this article in order to ensure sealing performance and operational safety during the experiment. Additionally, a host computer software is presented in this article for data recording and analysis to realize real-time recording and saving of experimental data, as well as generating pressure curves. The flange-type apparatus is calibrated mainly through the measurement of two metrological parameters, which are indication error and set pressure retention error. Experimental verification has confirmed that this method can simultaneously calibrate both parameters, which can significantly improve the accuracy and efficiency of on-site calibration of flange-type apparatus to measure the water permeability of concrete.

Hybrid rib fabric electromagnetic shielding measurement in X-band

This study involves measurement and evaluation of the electromagnetic shielding effectiveness (EMSE) in the X-band frequency range of rib-knitted fabrics formed from hybrid conductors. Hybrid conductive fabrics were made by knitting copper, silver, and stainless steel conductors together with cotton yarn. The basic theory of EMSE is introduced, and the waveguide measurement setup described. The through-reflect-line calibration setup was used to obtain accurate results. After calibration of the established waveguide measurement setup, hybrid conductive fabrics were tested. The measurements were analyzed and the fabrics compared. The aim is to produce a hybrid fabric that is suitable for general use, has a good EMSE, is easy to produce, and offers low-cost high-frequency solutions. An easy-to-produce and low-cost EMSE material is required, especially in new-generation wearable flexible electronic devices and military applications.

Reliable metrology for infrasound sensors

The reliable assessment of infrasound has become increasingly important in the last years. Reliable measurements require calibration of the employed sensors with traceability to the SI. While there is measurement equipment capable of measuring infrasound available, there is no sufficient calibration below 10 Hz. Traceability for airborne sound is currently realized by primary calibration methods which are applicable down to 2 Hz, with limitations below 10 Hz. Against that background, a primary and a secondary calibration setup have been developed at PTB. Together they enable the traceable calibration of a variety of infrasound sensors such as microphones, sound level meters or microbarometers. Moreover in practice, procedures are necessary which ensure reliable results in a field environment even with external disturbances. A field study was conducted comparing the performance of measurement microphones and microbarometers at a wind park. Emphasis was placed on different means of protection against wind induced noise. Additionally, a laboratory study investigated the influence of small damages to a microphone diaphragm on the reliability of the microphone. In this contribution, the newly developed calibration setups for infrasound sensors and the insights from the field and laboratory studies are presented.

Going beyond hardware limitations with advanced stray light calibration for the Metop-3MI space instrument

Space optical instruments play a pivotal role in enhancing our understanding of the universe and our planet, and are crucial in addressing the urgent challenges posed by climate change. In this context, stray light has emerged as a primary performance limitation. Originating from ghost reflections or scattering, it obscures essential details and introduces false information into images. With the demand for increasingly high-performing instruments, mitigation through hardware optimization is becoming insufficient. We are entering an era where future instruments require a stray light correction algorithm to meet user specifications, necessitating extensive on-ground calibration. This paper examines the Metop-3MI Earth observation instrument, which, with wide field of view, broad spectral range, and multi-polarization capabilities, epitomizes the challenges of stray light calibration and correction. A custom calibration apparatus was constructed to evaluate the complex stray light dependence on field-of-view, wavelength, and polarization. Data were processed, and stray light kernels database was derived, which then fed into a specially developed correction algorithm. Applied to the image of an extended scene, it effectively reduces stray light by a remarkable factor of 91. This achievement sets a new standard for low-stray-light instruments and provides a comprehensive case study for future missions.

Characterization of Gamma Spectroscopy Setup, Efficiency Calibration of HPGe detector used for Radiological substances

Background: Contamination of radiological substances in environment is one of the most important factors and harmful for living beings if the activity is high enough with long half-life.‘Gamma Spectrometry Setup’ is comparatively better for detection and analysis of gamma radiations in any type of specimens. Initiating the data acquisition setup, it’s essential to calibrate the entire setup for accuracy measurement. Materials and Methods:The main purpose of the research work is to characterize the data acquisition setup using137Cs and 60Co point sources. 137Cs emits γ-rays of 661.66 keV and 60Coemits two different γ-rays; 1173.2 KeV & 1332.5 KeV. Setup standardization is an essential part of any research works. Results: The HPGe detector used with the setup is also good enough for γ-energy detection. Detector efficiency calibration is another major task needed for activity calculation, using gamma energy lines detected in a sample detector efficiency can be calculated. Conclusion: Initiating every research experiment, the setup calibration should be checked for accurate results

Upgrade of the Lyman-alpha diagnostic system on DIII-D for main chamber edge neutral studies.

The LLAMA (Lyman Alpha Measurement Apparatus) pinhole camera diagnostic had previously been deployed on DIII-D to measure radial profiles of the Lyman-α (Ly-α) deuterium neutral line brightness across the plasma boundary in the lower chamber to infer neutral deuterium density and ionization rate profiles. This system has recently been upgraded with a new diagnostic head, named ALPACA, that also encloses two pinhole cameras and duplicates the LLAMA views in the upper chamber. Similar to LLAMA, ALPACA provides two times 20 lines of sight, viewing the plasma edge on the inboard and outboard sides with a radial resolution of ∼2.5 cm (FWHM) and an effective time resolution of ∼1 ms that allows for the investigation of inter-ELM dynamics. The extended Ly-α system provides better coverage to study neutrals in experiments with various plasma shapes utilizing both the upper and lower divertors. Furthermore, post-campaign calibration of the LLAMA diagnostic has successfully been demonstrated for the first time. This was facilitated by various upgrades to the calibration set-up and detailed measurements of the emissivity distribution of the Ly-α calibration source using a pinhole collimator. It was found that the sensitivity of the inboard LLAMA pinhole camera was reduced by a factor of 2.0 ± 0.2 over the course of six months of plasma operation in 2021. The upgraded Ly-α system, equipped with improved absolute calibration, will provide key input for neutral fueling and pedestal particle transport studies and for 2D edge transport code validation on the DIII-D tokamak.

The dynamic response of a pressure transducer for measurements in water

Dynamic pressure measurements are indispensable in the field of fluid mechanics. Attaching tubing as a transmission line to the pressure transducer is often unavoidable but significantly reduces the usable bandwidth of the measurement system. Complex fluid-wall interactions and potential outgassing of air are present within systems with water-filled tubes. Comprehensive studies aiding researchers in selecting suitable transmission line parameters (i.e., material, length, and diameter) are not available. A simple calibration apparatus is designed for the frequency response characterization of multiple pressure transducers simultaneously applying a pressure step. The setup is thoroughly characterized and a detailed description is provided to optimize the bandwidth. A piezoresistive pressure transducer attached to water-filled tubes, as commonly used in hydrodynamic experiments, is characterized in the low-frequency range (i.e., f≤300\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$f \\le {300}$$\\end{document} Hz). Tube-related effects, such as length, diameter, and material are investigated. The impact of entrapped air within the tubing is analyzed. The feasibility of substituting water with silicone oil to fill the tubes is explored. To optimize the usable bandwidth of the pressure measurement system for dynamic applications, it is essential to maintain short tubing that is as rigid as possible and free from entrapped air. Pressure wave propagation speed is reduced by two orders of magnitude in elastic transmission lines made of silicone. Pressure corrections through dynamic calibration are challenging due to the system’s sensitivity to various parameters affecting the dynamic response.

Facile barometric calibration of photoluminescence-based oxygen sensors on a standard rotary evaporator system with a digital vacuum pump

A simple setup and methodology for barometric calibration of quenched phosphorescence oxygen sensors are described, which utilize a standard rotary evaporator (Rotavap) system equipped with a digital vacuum pump. They were demonstrated with a panel of different sensing materials based on PtBP dye, including solid-state sensor coatings on different substrates (membrane inserts, stickers or inner wall of the vacuum flask), as well as liquid sensor formulations. The sensors inside the flask were exposed to different conditions created by the Rotavap system (dry or humid air, water, temperatures ranging 2°C-40°C, residual total pressure), and their intensity, lifetime or phase shift signals were measured with handheld sensor readers Optech (Mocon) and Firesting (PyroScience) in a contact-less manner to generate multi-point calibration curves. Several critical points of the method, which require careful consideration, have been revealed, including sensor mounting inside the Rotavap, its temperature control during calibration, choice of the reader. Finally, a detailed characterization of several sensor types was carried out and their key operational parameters (τ0, KSV, heterogeneity, T-coefficients), and calibration equations for the different conditions were determined and compared to each other and the results of conventional O2 calibration. Overall, barometric calibration method using Rotavap provides a useful alternative to conventional O2 calibration methods, being simple, accurate, convenient and versatile.

Calibration and characterization of optical and x-ray streak cameras using a Ti:Sapphire laser system.

Optical and x-ray streak cameras are used to study transient phenomena, particularly in the high-energy density physics regime. The Orion laser facility employs many different types of streak cameras, which are used to collect data on laser-plasma interactions as well as to verify the temporal profile and timing between the multiple Orion beamlines. Streak cameras are complex devices with very precise timing associated with them, which can often malfunction, resulting in the loss of shot data. Since Orion is a kJ-class Nd:glass laser system, it is not optimal to try and fault-find using Orion shots since this is both time consuming and prohibitively expensive. To enable the facile set-up, fault-finding, timing-in, and in-house calibration of Orion optical and x-ray diagnostics, a single laboratory system has been commissioned to provide an adjustable stimulus to streak cameras and other Orion short pulse diagnostics (such as pulse dilation photomultiplier tubes). The system comprises a Ti:Sapphire laser system capable of generating 400nm or 266nm laser pulses of duration less than 0.1ps; an optical system to deliver single pulses, pulse pairs, or a train of pulses; and timing electronics to synchronize the streak cameras with the laser and to record output data. The system can operate at Hertz repetition rates rather than the sub-mHz rate of the Orion laser. We present the commissioned system and results from initial testing of both optical and x-ray streak cameras used on Orion laser-plasma experiments.

82‐1: Distinguished Paper: Geometric Distortion on Video See‐Through Head‐Mounted Displays

We evaluate the geometric distortion on video see‐through (VST) head‐mounted displays (HMDs) with single‐camera and dualcamera design. We present the experimental setup and metrology for geometric calibration and VST geometric distortion measurement. Physical geometric distortion is compared to the distortion of digital content on a VST HMD. We investigate the impacts of camera misalignment and depth distance on VST geometric distortion with angular‐based distortion correction.

Полуэмпирическое моделирование температуры резания и шероховатости поверхности при точении конструкционных материалов твердосплавным инструментом с покрытием TiAlN

Introduction. In manufacturing, obtaining a specified surface roughness of the machined components is of great importance to fulfill functional requirements. However, this is significantly affected by the heat generated during processing, potentially causing variations in dimensional accuracy. The surface roughness significantly affects the fatigue performance of the component, while the cutting tool's lifespan is dictated by the generation of cutting temperatures. The purpose of the study is to create semi-empirical models for predicting surface roughness and temperature of different work materials. Improved cutting performance is achieved by precisely determining the cutting temperature in the zone being machined. However, calculating the cutting temperature for each specific case is fraught with difficulties in terms of labor resources and financial investments. This paper presents a comprehensive empirical formula designed to predict both theoretical temperature and surface roughness. The methodology. The surface roughness and temperature values were evaluated for EN 8, Al 380, SS 316 and SAE 8620 materials using TiAlN coated carbide tool. The TiAlN coating was formed using Physical Vapor Deposition (PVD) Technique. The response surface methodology was used to prepare predictive models. Cutting speed (140 to 340 m/min), feed (0.08 to 0.24 mm/rev) and depth of cut (0.6 to 1.0 mm) was used as input parameters for measuring the performance of all material in terms of surface roughness and cutting temperature. The tool-work thermocouple principle was used to measure the temperature at the chip-tool interface. A Novel Calibration Setup was developed to establish a connection between the electromotive force (EMF) generated during machining and the cutting temperature. Results and Discussion. It is observed that the power required for machining was largely transformed into heat. The highest cutting temperature is recorded when machining of SS 316 followed by SAE 8620, EN 8. However, low temperature is reported during machining of Al 380 and it is mainly governed by the thermal conductivity of the material. The lowest surface roughness is observed in SAE 8620, EN 8 material followed by SS 316 and Al 380. Semi-empirical method and regression model equations show a good agreement with each other. Statistical analysis of nonlinear estimation reveals that the cutting speed, feed, and density of the material have a greater effect on surface roughness, whereas the depth of cut has a greater effect on temperature generation. The study will be very useful for predicting industrial productivity when machining of EN 8, Al 380, SS 316 and SAE 8620 materials with TiAlN-coated carbide tool.

Recent Upgrade of the Magnetic Diagnostic System in the Alvand-U Tokamak

The main acting parameters in tokamak plasma experiments, such as currents and electric and magnetic fields, are present inside and outside the plasma volume. To analyze the changes in the shape of tokamak plasma, it is necessary to use experimental data obtained from magnetic measurements. Until recently, a four-digit magnetic probe (MP) was used for qualitative analysis of the magnetic field, but its accuracy was low, and it could not be practically used as a diagnostic system. Following the Magnetic Confinement Group, Tokamak Laboratories’ approach to optimize and improve the measurement of plasma parameters, the use of a richer array of MPs to accurately measure changes in the magnetic field and identify plasma parameters in the Alvand tokamak was considered. In order to upgrade the magnetic diagnostic system, two MP arrays were designed and manufactured. Each array contains 12 poloidal and radial probes. The MPs of each array were attached to Mylar belts and mounted on the vacuum vessel of the tokamak. In addition, an integrator unit was designed and installed as a magnetic diagnostic subsystem. The conducted research involved the MP and calibration setup followed by preliminary tests of the array probe.

Accurate on Wafer Calibration and S-parameter Measurement Setup for InP-based HEMT Devices to 220 GHz

Accurate on Wafer Calibration and S-parameter Measurement Setup for InP-based HEMT Devices to 220 GHz

Precise Synergistic Photothermal Therapy Guided by Accurate Temperature‐Dependent NIR‐II Fluorescence Imaging

AbstractPhotothermal therapy (PTT) is considered a promising treatment strategy for solid tumors. However, local hyperthermia (over 45°C) during PTT can cause severe side effects in neighboring healthy tissues. PTT with accurate temperature feedback is a compelling strategy to ablate tumors and reduce side effects, but it still faces challenges. Here, a new kind of phototheranostic nanoparticle, namely 17‐RF@Ag2Se is developed, enabling in vivo NIR‐II fluorescence tracking, PTT and fluorescence nanothermometry as well as synergistic heat‐shock protein (HSP) inhibition. Precise PTT with high spatiotemporal resolution is achieved with the help of the designed NIR‐II fluorescence imaging‐photothermal therapy linkage apparatus. Upon intravenous injection, 17‐RF@Ag2Se is specifically accumulated in tumors targeted by the overexpressed integrin αvβ3, which is monitored by NIR‐II fluorescence imaging of Ag2Se QDs. Further, the release of HSP inhibitor, tanespimycin (17‐AAG), enhances the thermosensitivity of tumor cells. Subsequently, the internal temperature of the tumor is precisely monitored and adjusted during PTT via the temperature‐dependent NIR‐II fluorescence feedback of Ag2Se QDs and the linkage apparatus calibration, thereby achieving efficient and safe tumor PTT. Also, the results present a new method for accurate temperature monitoring and control in vivo, which can be applied to other biomedical studies.

Magnetic field regression using artificial neural networks for cold atom experiments

Accurately measuring magnetic fields is essential for magnetic-field sensitive experiments in areas like atomic, molecular, and optical physics, condensed matter experiments, and other areas. However, since many experiments are often conducted in an isolated environment that is inaccessible to experimentalists, it can be challenging to accurately determine the magnetic field at the target location. Here, we propose an efficient method for detecting magnetic fields with the assistance of an artificial neural network (NN). Instead of measuring the magnetic field directly at the desired location, we detect fields at several surrounding positions, and a trained NN can accurately predict the magnetic field at the target location. After training, we achieve a below 0.3% relative prediction error of magnetic field magnitude at the center of the vacuum chamber, and successfully apply this method to our erbium quantum gas apparatus for accurate calibration of magnetic field and long-term monitoring of environmental stray magnetic field. The demonstrated approach significantly simplifies the process of determining magnetic fields in isolated environments and can be applied to various research fields across a wide range of magnetic field magnitudes.