Measurement Capabilities Research Articles

International comparisons in the field of measuring specific adsorption of gases and specific surface area of solids: optimizing the number of comparisons to ensure calibration and measurement capabilities

International comparisons in the field of measuring specific adsorption of gases and specific surface area of solids: optimizing the number of comparisons to ensure calibration and measurement capabilities

Crack analysis of tall concrete wind towers using an ad-hoc deep multiscale encoder–decoder with depth separable convolutions under severely imbalanced data

An accurate and timely cracking assessment, including the presence, location and crack geometric feature measurement, is crucial for evaluating concrete wind towers. Therefore, the early identification of cracks is a critical procedure in promptly evaluating structural integrity. This study proposed an ad-hoc encoder–decoder network based on DeepLabv3+ with depth separable convolutions to automatically segment cracks from real-world images captured from various concrete wind towers. The combined advantages of the improved DeepLabv3+ and the lightweight MobileNet v2 are suitable as a benchmark due to their high performance and universality. Four experiments were conducted to determine the model design choice and crack feature measurement capability: (1) six parametric tests using various pre-trained base networks and algorithm optimisers, (2) the influence of complex background noise (i.e., handwriting script) on crack segmentation performance, (3) comparative studies with cutting-edge pixel-wise segmentation models and (4) crack feature measurement (i.e., length and width). The research outcome demonstrated that DeepLabv3+ with MobileNet v2 can potentially be applied for efficient and accurate crack segmentation in concrete wind towers with complex backgrounds.

Ultra high-speed 3D shape measurement technology for specular surfaces based on μPMD

Phase measuring deflectometry (PMD) has been extensively applied to measure specular surfaces due to its non-contact, high-precision, full-field measurement capabilities. Liquid crystal display (LCD) screen is the most common structured light source in PMD. However, the response time of liquid crystal molecules limits its frame rate to around 100 frames per second (fps). Therefore, it is quite difficult for traditional PMD to measure rapidly moving surfaces. This paper proposes a 3D dynamic sensing technique, microsecond-PMD (µPMD) based on the high-frame-rate sinusoidal fringe display (HSFD). In the proposed method, the switching time for each fringe pattern display is at a sub-microsecond level, enabling high-speed fringe acquisition with kHz-level area array detection or 100kHz-level line array scanning. The HSFD method uses a specially designed LED array and two-step optical expansion. The high-speed switching characteristic of LED sources is utilized to allow a superfast display rate. Moreover, the superior sinusoidal property can be achieved by the combination of the specially designed discrete sinusoidal LED array, the light-diffracting effect of orthogonal gratings, and the filtering effect of the light diffuser. The mechanism and analytic model of fringe generation are thoroughly analyzed and discussed in this work. Furthermore, the swarm optimization algorithm and corresponding weighted fringe quality evaluation function are presented to obtain the optimal fringes. To the best of our knowledge, the proposed µPMD, for the first time, achieved a superfast fringe acquisition rate of 4000fps with sub-micrometer precision in three-dimensional (3D) reconstruction for specular surfaces. We envision this proposal to be broadly implemented for real-time monitoring in manufacturing.

Application of noncontact sensors for cardiopulmonary physiology and body weight monitoring at home: A narrative review.

Monitoring health status at home has garnered increasing interest. Therefore, this study investigated the potential feasibility of using noncontact sensors in actual home settings. We searched PubMed for relevant studies published until February 19, 2024, using the keywords "home-based," "home," "monitoring," "sensor," and "noncontact." The studies included in this review involved the installation of noncontact sensors in actual home settings and the evaluation of their performance for health status monitoring. Among the 3 included studies, 2 monitored respiratory status during sleep and 1 monitored body weight and cardiopulmonary physiology. Measurements such as heart rate, respiratory rate, and body weight obtained with noncontact sensors were compared with the results obtained from polysomnography, polygraphy, and commercial scales. All included studies demonstrated that noncontact sensors produced results comparable to those of standard measurement tools, confirming their excellent capability for biometric measurements. Overall, noncontact sensors have sufficient potential for monitoring health status at home.

Multilayer Structure Damage Detection Using Optical Fiber Acoustic Sensing and Machine Learning.

Over the past decade, distributed acoustic sensing has been utilized for structural health monitoring in various applications, owing to its continuous measurement capability in both time and space and its ability to deliver extensive data on the conditions of large structures using just a single optical cable. This work aims to evaluate the performance of distributed acoustic sensing for monitoring a multilayer structure on a laboratory scale. The proposed structure comprises four layers: a medium-density fiberboard and three rigid polyurethane foam slabs. Three different damages were emulated in the structure: two in the first layer of rigid polyurethane foam and another in the medium-density fiberboard layer. The results include the detection of the mechanical wave, comparing the response with point sensors used for reference, and evaluating how the measured signal behaves in time and frequency in the face of different damages in the multilayer structure. The tests demonstrate that evaluating signals in both time and frequency domains presents different characteristics for each condition analyzed. The supervised support vector machine classifier was used to automate the classification of these damages, achieving an accuracy of 93%. The combination of distributed acoustic sensing with this learning algorithm creates the condition for developing a smart tool for monitoring multilayer structures.

Modeling and observations of North Atlantic cyclones: Implications for U.S. Offshore wind energy

To meet the Biden-Harris administration's goal of deploying 30 GW of offshore wind power by 2030 and 110 GW by 2050, expansion of wind energy into U.S. territorial waters prone to tropical cyclones (TCs) and extratropical cyclones (ETCs) is essential. This requires a deeper understanding of cyclone-related risks and the development of robust, resilient offshore wind energy systems. This paper provides a comprehensive review of state-of-the-science measurement and modeling capabilities for studying TCs and ETCs, and their impacts across various spatial and temporal scales. We explore measurement capabilities for environments influenced by TCs and ETCs, including near-surface and vertical profiles of critical variables that characterize these cyclones. The capabilities and limitations of Earth system and mesoscale models are assessed for their effectiveness in capturing atmosphere–ocean–wave interactions that influence TC/ETC-induced risks under a changing climate. Additionally, we discuss microscale modeling capabilities designed to bridge scale gaps from the weather scale (a few kilometers) to the turbine scale (dozens to a few meters). We also review machine learning (ML)-based, data-driven models for simulating TC/ETC events at both weather and wind turbine scales. Special attention is given to extreme metocean conditions like extreme wind gusts, rapid wind direction changes, and high waves, which pose threats to offshore wind energy infrastructure. Finally, the paper outlines the research challenges and future directions needed to enhance the resilience and design of next-generation offshore wind turbines against extreme weather conditions.

Cavity ionization chamber responses in the JAEA and the NMIJ high-energy photon reference fields for radiation protection

The dosimeter response should be calibrated in a reference field near the user's radiation environment. Environments around nuclear reactors and radition therapy facilities have high-energy photons with energies exceeding that of60Co gamma rays, and controlling exposure to these photons is important. The Japan Atomic Energy Agency (JAEA) and National Metrology Institute of Japan (NMIJ) have high-energy reference fields with energies above several MeV for different types of accelerators. Their reference fields have different fluence-energy distributions. In this study, the energy dependencies of the two-cavity ionization chambers, which are often used by secondary laboratories, were experimentally and computationally evaluated for each high-energy field. These results agreed well with relative expanded uncertainties (k= 2), and their capabilities for air kerma measurements in each high-energy reference field were confirmed. Therefore, the capabilities of the air-kerma measurements can be verified in the two high-energy reference fields.&#xD.

Measurement Capability Evaluation of Acoustic Emission Sensors in IIoT System for PHM

Measurement Capability Evaluation of Acoustic Emission Sensors in IIoT System for PHM

Research on data processing technology based on 6LiF/ZnO:Ga fiber neutron detector array

The 6LiF/ZnO:Ga fiber neutron detector, consisting of a 6LiF/ZnO:Ga scintillator, optical fiber, and PMT, has distinct advantages such as compactness, strong real-time online measurement capabilities, and resistance to electromagnetic interference. These characteristics make it highly suitable for neutron detection in confined spaces with significant electromagnetic interference. However, its small size limits the neutron detection efficiency of a single detector, necessitating the use of multiple fibers to construct a fiber array and enhance sensitivity. The goal is to study data processing techniques for the 6LiF/ZnO:Ga fiber detector array. Inside the FPGA, three digital signal processing channels are used to extract multiple information from signal such as the amplitude, timestamp, and measurement channel ID. The fast channel adopts triangular shaping to provide real-time baselines and timestamps for the discrimination channel and the slow channel. The slow channel adopt cascade shaping method to extract the amplitude of nuclear signal. The discrimination channel method adopt cascade discrimination method to realize the real-time discrimination between gamma signals, neutron signals and interference signals. The method has been successfully applied to 6LiF/ZnO:Ga fiber neutron detector arrays with different mass ratios, providing new solution for digital data processing in fiber neutron detector arrays.

Pharmaceutical Applications and Advances with Zetasizer: An Essential Analytical Tool for Size and Zeta Potential Analysis

: Zetasizer is an advanced device that measures various properties of particles or molecules suspended in a liquid medium. It is extensively used for evaluating the size of nanoparticles, colloids, and biomolecular particles, and for determining particle charge. There are several analytical techniques by which the size, zeta potential, and molecular weight can be determined, like Dynamic Light Scattering (DLS) that measures the size of particles in dispersed systems, which can range from sub-nanometers to several micrometers in diameter. Electrophoretic Light Scattering (ELS) analyzes the mobility and charge of particles, also known as the zeta potential. Static Light Scattering (SLS) determines the molecular weight of particles in a solution. The Zetasizer is part of the Zetasizer Advance range of benchtop systems available for laboratory use. The Zetasizer Ultra model offers unique measurement capabilities, such as Multi-angle Dynamic Light Scattering (MADLS) and particle concentration. These features offer a deeper understanding of samples, making the Zetasizer a vital instrument in numerous scientific and industrial applications. In this review, we have discussed Zetasizer’s principles for the determination of particle size, zeta potential, and molecular weight, along with its qualification and applications in different formulations.

Baseline measurements in the assessment of ESS-specific radionuclide uptake by crops cultivated in Southern Sweden

The European Spallation Source, ESS, is a neutron research facility under construction in Lund, Southern Sweden. The Facility will produce neutrons by spallation, using a powerful linear accelerator to deliver protons to a tungsten target. In addition to the desired neutron production, a long list of radionuclides will be created as by-products of the nuclear reaction inside the target. The Swedish Radiation Safety Authority has established a list of the most relevant radionuclides, in terms of contribution to the effective dose to ESS workers and the general public, should an accidental release of irradiated target material occur. This list includes radionuclides that are not produced by the nuclear energy industry, in particular 178mHf, 182Ta, 187W, 148Gd and 173Lu. Ongoing research efforts aim to determine the best analytical methods to assess these exotic and often difficult-to-measure radionuclides in environmental samples. This work investigates the potential of X-ray fluorescence and time-of-flight elastic Recoil detection analysis for the assessment of soil samples, and the potential of particle induced X-ray emission for the assessment of crop samples. These techniques require only simple sample preparation steps and no chemical extraction, unlike the conventional environmental monitoring methods such as inductively-coupled plasma mass spectrometry, and show promise as complimentary methods enabling fast sample throughput. This study focuses on the analysis of uncontaminated soil and crops, to provide baseline data, whilst simultaneously assessing the available measurement capabilities. For the X-ray fluorescence system used in this study, the method detection limit for W in soil was determined to be 0.147ppth, and Zr which can be correlated with the migration of Hf was clearly measurable.

Strategy for Compensation of Thermally Induced Displacements in Machine Structures Using Distributed Temperature Field Control

Thermal deformation is a major source of machining errors in modern machine tools. In addition to optimising the machine structure, correcting the axis position values in the numerical control is a common measure to reduce these errors. Another possibility is to directly influence the temperature field of the machine tool in the process, which requires a complex thermo-elastic modelling approach as well as appropriate thermal actuation and measurement capabilities. This paper presents a strategy for controlling the temperature field based on the eigenmodes of the thermal system. The various aspects of the concept are explained using a finite element model of an exemplary structural component. The basis is the modal analysis of the thermal system, which allows the temperature field to be described by independent discrete states. In addition to the placement of thermal sensors and actuators, this work focuses on the design of a suitable control approach. Transient simulation results are used to clearly demonstrate the performance of this method.

Quantification of the Uncertainty in Ultrasonic Wave Speed in Concrete: Application to Temperature Monitoring with Embedded Transducers.

This article presents an overall examination of how small temperature fluctuations affect P-wave velocity (Vp) measurements and their uncertainties in concrete using embedded piezoelectric transducers. This study highlights the fabrication of custom transducers tailored for long-term concrete monitoring. Accurate and reliable estimation of ultrasonic wave velocities is challenging, since they can be impacted by multiple experimental and environmental factors. In this work, a reliable methodology incorporating correction models is introduced for the quantification of uncertainties in ultrasonic absolute and relative velocity measurements. The study identifies significant influence quantities and suggests uncertainty estimation laws, enhancing measurement accuracy. Determining the onset time of the signal is very time-consuming if the onset is picked manually. After testing various methods to pinpoint the onset time, we selected the Akaike Information Criterion (AIC) due to its ability to produce sufficiently reliable results. Then, signal correlation was used to determine the influence of temperature (20 °C to 40 °C) on Vp in different concrete samples. This technique proved effective in evaluating velocity changes, revealing a persistent velocity decrease with temperature increases for various concrete compositions. The study demonstrated the capability of ultrasonic measurements to detect small variations in the state of concrete under the influence of environmental variables like temperature, underlining the importance of incorporating all influencing factors.

Indirect optical geometry measurements with a stream of particles as micro probes

The manufacturing of micro-structured components with varying geometries and materials requires precise and versatile applicable geometry measurement techniques. Optical measurement approaches enable high-precision measurements, but they rely on cooperative surfaces. To overcome the dependency on the optical surface response, the surface of a measured object is determined indirectly using an aerosol flow with fluorescent particles and a confocal fluorescence microscope. To precisely extract the surface position from the scanned fluorescence signal of the particles in the surrounding air, a model-based signal processing is proposed. To assess the measurement capabilities and the influence of the aerosol supply flow, geometry and flow measurements are performed on a flat plate geometry and a step geometry. As a result, a measurement uncertainty of ▪ with no systematic error was achieved for the flat plate experiment, despite the different boundary layer flows at the different measurement positions. In contrast to this, a significant systematic measurement error occurred in the wake flow region of the step geometry because of flow separation and, thus, no detectable particles directly behind the step. In summary, the findings clarify an in principle achievable sub-micrometre resolution with improved optics and a large number of detected particles, but also emphasise the necessity of a sufficient particle supply for enabling indirect optical geometry measurements.

High-resolution wind speed measurements with quadcopter uncrewed aerial systems: calibration and verification in a wind tunnel with an active grid

Abstract. As a contribution to closing observational gaps in the atmospheric boundary layer (ABL), the Simultaneous Wind measurement with Uncrewed Flight Systems in 3D (SWUF-3D) fleet of uncrewed aerial systems (UASs) is utilized for in situ measurements of turbulence. To date, the coefficients for the transformation terms used in our algorithm for deriving wind speeds from avionic data have only been determined via calibration flights in the free field. Therefore, we present in this work calibration and verification under laboratory conditions. The UAS measurements are performed in a wind tunnel equipped with an active grid and constant temperature anemometers (CTAs) as a reference. Calibration is performed in x- and y-coordinate directions of the UAS body frame at wind speeds of 2 … 18 m s−1. For systematic verification of the measurement capabilities and identification of limitations, different measurement scenarios like gusts, velocity steps, and turbulence are generated with the active grid. Furthermore, the measurement accuracy under different angles of sideslip (AoSs) and wind speeds is investigated, and we examined whether the calibration coefficients can be ported to other UASs in the fleet. Our analyses show that the uncertainty in measuring the wind speed depends on the wind speed magnitude and increases with extreme velocity changes and with higher wind speeds, resulting in a root-mean-square error (RMSE) of less than 0.2 m s−1 for steady wind speeds. Applying the calibration coefficients from one UAS to others within the fleet results in comparable accuracies. Flights in gusts of different strengths yield an RMSE of up to 0.6 m s−1. The maximal RMSE occurs in the most extreme velocity steps (i.e., a lower speed of 5 m s−1 and an amplitude of 10 m s−1) and exceeds 1.3 m s−1. For variances below approx. 0.5 and 0.3 m2 s−2, the maximal resolvable frequencies of the turbulence are about 2 and 1 Hz, respectively. The results indicate successful calibration but with susceptibility to high AoSs in high wind speeds, no necessity for wind tunnel calibration for individual UASs, and the need for further research regarding turbulence analysis.

Quantification of Clitidine in Paralepistopsis acromelalga Using Quantitative NMR Method

Because one toxic component of Paralepistopsis acromelalga, clitidine, is not commercially available as a reagent and because standards are difficult to obtain, a quantitative NMR method that requires no standard was investigated for this study. To compare the quantitative values obtained using the two methods, the absolute purity of the standard used for the LC-MS/MS method was calculated using quantitative NMR. The result was calculated as 89.8±1.5%: more than 10% lower than the result obtained using conventional HPLC purity. This finding is presumably attributable to the presence of water in the crystals. Calculating the absolute purity of the product before use is crucially important. The values of the Paralepistopsis acromelalga fruit extract were quantified and compared using conventional LC-MS/MS and quantitative NMR. The quantitative values did not differ significantly, suggesting that, in most cases, they were within a 5% margin of error. Furthermore, quantitative NMR provides several benefits not obtained using conventional methods, including its rapid measurement capability and its obviation of the need for a reference material for the measured substance. By virtue of these benefits, quantitative NMR is an extremely useful tool for natural toxin analysis where sudden outbreaks occur and for which rapid calculation of results is necessary.

Calibration methods for high frequencies: Development and validation

The paper presents an introduction of an advanced method for calibration of high-frequency instruments, such as oscilloscopes, frequency counters and function generators that operate at the frequencies between 1 MHz and GHz range. Based on conducted thorough survey of the needs for calibration of high-frequency measurement devices in the region of Southeast Europe, and the identified calibration and measurement capability gap in comparison to the international metrology offer, the Laboratory for Electrical Measurements at Ss. Cyril and Methodius University in Skopje developed new methods, following the general recommendations of the EURAMET cg-7 Calibration Guide. An original approach in the design of the experimental procedure, and a novel data fusion concept for the evaluation of the measurement uncertainty is deployed. The paper also investigates and resolves some challenges of setting up an unbroken measurement traceability chain, and uncertainty estimation for calibration in the domain of high frequencies. The established and accredited calibration capabilities are essential for the region of Southeast Europe, where the metrology facilities for the calibration/testing of high frequency electronic devices are inadequate to meet the conformity assessment needs of the quickly growing automotive supply chain sector, and the needs of other electrical and electronic industries.

Improvement of metrology infrastructure in the area of extreme impedance calibrations

The paper describes how the Laboratory for Electrical Measurements at the Ss. Cyril and Methodius University in Skopje, an accredited calibration laboratory, enhanced its calibration and measurement capabilities for extreme values of electrical impedance. This was conducted through development of new calibration methods for instruments that measure extreme electrical resistance and inductance. The paper also explains how these methods were validated to ensure traceability and how the measurement uncertainty in impedance instruments calibration was innovatively estimated, by deploying the data fusion concept to increase the metrology infrastructure capacity. As the testing facilities for electrical quantities in Southeast Europe are not sufficiently developed, and some calibration areas of electrical instruments are not well provided by the existing laboratories, despite the economic and scientific demands, the relevance of this metrology infrastructure upgrade is evident.

Cross-concentration calibration of low-cost sensors for effective dust monitoring at construction sites

Building activities commonly generate substantial amounts of construction dust, adversely affecting the nearby environment and public health. Construction workers, in particular, face significant health hazards due to their prolonged exposure to elevated levels of this dust. Traditional method of monitoring individual exposure to construction dust, such as gravimetric samplers or high-end analytical instruments, are often expensive, cumbersome, and not suitable for real-time, widespread deployment. This study employs the low-cost sensors (PMS A003-G10) to measure dust concentrations in varied environments: first low, then high, and then once again low concentrations. In the first low-concentration environment, the G10 sensors showed strong correlation (R2 > 0.81) and acceptable error (RMSE<13.6 μg/m3). However, in high-concentration environment, the G10 sensor faced range limitation issues, yet maintained good correlation. Post high-concentration exposure, the G10 sensor exhibited increased NRMSE and MAPE, indicating adverse impacts on its measurement capability. To enhance the G10's performance in high concentrations, temperature and humidity were used as calibration factors. Four machine learning algorithms (MLR, RF, KNN, and XGBoost) were compared, with XGBoost demonstrating superior calibration (R2 > 0.96, RMSE<117.1 μg/m3). The model's generalizability was validated by integrating data from both low and high-concentration environments into the XGBoost training. Subsequent application to the second low-concentration dataset post high-concentration exposure assessed the model's generalizability and applicability. This study demonstrates that with appropriate calibration, low-cost sensors can effectively monitor individual exposure to construction dust across diverse concentration levels.

Mechanoluminescence of ZnS: Cu@Al2O3 enabled optical fiber microlens passive tactile sensor for hardness recognition.

We propose an optical fiber microlens (OFM) passive tactile sensor (OFMPTS) for hardness recognition. The sensor features a core-shell structure, with an OFM as the core and an elastic mechanoluminescence (ML) matrix shell, which is composed of ZnS: Cu@Al2O3 doped with 10 nm SiO2 particles and polydimethylsiloxane (PDMS). Utilizing the Hertz model, the ML intensity of the sensor is correlated to the elastic modulus of the sample, which enables precise hardness detection. The microlens fiber structure significantly enhances photon collection efficiency, thereby allowing for effective coupling of the ML signal. In press mode, OFMPTS differentiates between five PDMS hardness levels. It can also operate in scan or tap mode, identifying hidden foreign bodies and tissue masses through response curve analysis. The sensor, which requires no external light source, expands the capabilities of optical hardness measurement.