Relative Measurement Error Research Articles

A simple conductivity measurement method using a peak-frequency feature of ferrite-cored eddy current sensor

Eddy current sensing (ECS) is advantageous in metallic measurements, but the existing ECS-based conductivity measurement methods are limited in terms of complexity, accuracy, or measurement range. Based on a peak-frequency feature of sweep-frequency eddy current sensor, a conductivity measurement method for non-magnetic plates is proposed. Deriving from the analytic solution of Dodd-Deeds, it is found that the peak-frequency, which is the peak frequency of the imaginary component of the induction spectrum change, is inversely proportional to the specimen's conductivity; the product of the conductivity and the peak-frequency is solely determined by a geometrical coupled parameter called spatial-frequency, which is independent of the conductivity of the specimen and is specified by the lift-off and the dimensions of sensor coils; the lift-off and the sensor coils dimensions have no impact on the inverse linearity between the conductivity and the peak-frequency, although produce different scales. The findings are also confirmed with finite element method (FEM) simulations and experimental results. Based on the findings, we propose to measure the conductivity using the inverse proportionality between the peak-frequency and the conductivity, and to eliminate the lift-off effect by calibrating the sensor with a known conductivity.In addition, we propose to use ferrite-cored sensor in experimental measurements, to improve the induction intensity in low frequency range in practical. The induction spectra characteristics of eddy current sensors with and without a ferrite core by FEM (finite element method) are compared, and the results show that the ferrite-cored eddy current sensor features the same peak-frequency as the air-cored eddy current sensor, but exhibits a stronger inductive impedance variation.Experiments were carried out on six samples with conductivities from 16.09 MS/m to 57.29 MS/m at different lift-offs. The relative conductivity measurement errors are within 1.26 % and the maximum absolute error is 0.43 MS/m. We analyze the measurement errors in terms of frequency resolution and lift-off, and propose methods for improvement. The conductivity measurement method based on the peak-frequency of ferrite-cored eddy current sensor shows its advantages in terms of simplicity, accuracy, immunity to the lift-off, and wide measuring range in non-magnetic metal plate conductivity measurements, because of the rarely mathematically approximation induced error and the determined inverse ratio between the conductivity and the peak-frequency.

Features of electrical conductivity at high temperatures of complex titanomagnetite ores from the Gusevogorsky deposit

Relevance is determined by the search and selection of the most information-intensive characteristics and physical properties of complex titanomagnetite ores in connection with the need for scientifically based criteria for their detection, quality assessment during selective mining and selection of optimal enrichment technology. Research methodology. To study the electrical properties, samples in the shape of a cube with an edge of 0.02 m were used. The measurements were carried out in an open system at atmospheric pressure. Electrical resistance was measured with a two-electrode setup every 10 degrees in the temperature range 20–800 ºC. Heating rate 0.066 deg/s. The measuring device is an E6-13 teraohmmeter with a dynamic range from 10 to 1014 Ohms and a relative measurement error from ±2.5% to 4% at the end of the range. Results. A collection of samples of complex titanomagnetite ores from the Gusevogorsky deposit (Northern quarry) was studied using physical, mineralogical and petrographic methods. Functional connections have been established between the electrical parameters of high-temperature electrical conductivity (Eₒ – activation energy, lg Rₒ – the so-called electrical resistance coefficient), the value and nature of the electrical resistance lg R in the temperature range 20−800 °C of the studied samples of complex ores with their structural and textural features and mineral composition. Based on structural and textural features, mineral composition and electrical parameters, the studied samples are clearly divided into three groups. Conclusions. The presented results, in combination with other physicochemical parameters, can be used as a reliable indicator of rapid assessment of the material being studied. Significant differences in the electrical parameters of titanomagnetite ores provide additional information about their quality. In combination with other methods, we hope for the possibility of using these parameters in the selective extraction of ores that require different enrichment regimes.

Оценка эффективности метода гиперплоскостей в задаче частичной идентификации неизвестного вещества

The problem of partial identification of a homogeneous medium of unknown chemical composition is investigated. The medium is subjected to repeated transillumination by X-ray fluxes collimated in energy and direction. According to the results of measuring the flux density of radiation entering and leaving the medium, it is necessary to establish the difference in the chemical composition of the medium from some in advance given substances. It is assumed that the measurements of radiation fluxes contain errors for which their maximum relative values are known. As a mathematical basis for the study the method of hyperplanes proposed earlier by the author is taken. The results of numerical calculations performed for problems of various dimensions and for a number of groups of specific chemical elements. Numerical estimates have been obtained for several groups of organic substances, under which any two substances will be successfully distinguished from each other by the results one single measurement experiment on transillumination. Using the hyperplane method in the identification problem for groups of organic substances showed enough high efficiency. As a result of computer calculations, it is shown that that any of the 1287 considered pairs of organic substances is well distinguishable if the total relative measurement error of the probing radiation flux does not exceed 9.726 \%. The analysis of the dependence of the mass attenuation coefficients of radiation from the atomic number for all chemical elements of the periodic system has been carried out and conclusions about the behavior of the identification accuracy with an increase in the dimension of the problem were done. A justification is given that the hyperplane method will be effective in solving the problem of identification for other groups of chemical elements and identification accuracy does not get worse as the dimension of the problem increases.

Metal Thickness Measurement System Based on a Double-Coil Eddy-Current Method With Characteristic Ratio Detection

Eddy-current sensor systems have been employed to determine the real-time thickness distribution of metal films and the thickness at endpoint detection in metal chemical mechanical polishing (CMP) processes, to achieve global planarization and avoid over-polishing or under-polishing. However, the large lift-off distance of 3.5 mm between the sensor coil and metal film gradually decreases with continuous wear of the polishing pad, which has a strong negative impact on the sensitivity and accuracy of the thickness measurement. In this study a double-coil eddy-current sensor system, with novel characteristic ratio detection capability, is proposed for metal film thickness measurement and compared with a traditional amplitude-based method. The linear relationship between the characteristic ratio and metal film thickness that is immune to lift-off distance is demonstrated both theoretically and experimentally. The experimental results show that the proposed method performs better than the amplitude-based method, reducing the effect of lift-off distance variation and obtaining an excellent linear measurement range from 24 to 2095 nm. The measurement accuracy is as high as 2.1 nm with an excitation frequency of 1.39 MHz and a large lift-off distance of 3.5 mm. The relative measurement error is less than 1.2% and the endpoint thickness ranges from 100 to 180 nm in the Cu-CMP process, when the lift-off distance varies from 3.6 to 3.3 mm.

High uncertainty aware localization and error optimization of mobile nodes for wireless sensor networks

<p>The localization of mobile sensor nodes in a wireless sensor network (WSN) is a key research area for the speedy development of wireless communication and microelectronics. The localization of mobile sensor nodes massively depends upon the received signal strength (RSS). Recently, the least squared relative error (LSRE) measurements are optimized using traditional semidefinite programming (SDP) and the location of the mobile sensor nodes was determined using the previous localization methods like least squared relative error and semidefinite programming (LSRE-SDP), and approximate nonlinear least squares and semidefinite programming (ANLS-SDP). Therefore, in this work, a novel high uncertainty aware-localization error correction and optimization (HUA-LECO) model is employed to minimize the aforementioned problems regarding the localization of mobile sensor nodes and enhance the performance efficiency of root mean square error (RMSE) results. Here, the position of target mobile sensor nodes is evaluated based on the gathered measurements while discarding faulty data. Here, an iterative weight updation approach is utilized to perform localization based on Monte Carlo simulations. Simulation results show significant improvement in terms of RMSE results in comparison with traditional LSRE-SDP and ANLS-SDP methods under high uncertainty.</p>

Variations and Depth of Formation of Submesoscale Eddy Structures in Satellite Ocean Color Data in the Southwestern Region of the Peter the Great Bay

The aim of this study was to develop methods for determining the most significant contrasts in satellite ocean color data arising in the presence of a submesoscale eddy structure, as well as to determine the corresponding depths of the upper layer of the sea where these contrasts are formed. The research was carried out on the example of the chain of submesoscale eddies identified in the Tumen River water transport area in the Japan/East Sea. MODIS Aqua/Terra satellite data of the remotely sensed reflectance (Rrs) and Rrs band ratio at various wavelengths, chlorophyll-a concentration, and, for comparison, sea surface temperature (sst) were analyzed. Additionally, the results of ship surveys in September 2009 were used to study the influence of eddy vertical structure on the obtained remote characteristics. The best characteristic for detecting the studied eddies in satellite ocean color data was the MODIS chlor_a standard product, which is an estimate of chlorophyll-a concentration obtained by a combination of the three-band reflectance difference algorithm (CI) for low concentrations and the band-ratio algorithm (OCx) for high concentrations. At the same time, the weakest contrasts were in sst data due to similar water heating inside and outside the eddies. The best eddy contrast-to-noise ratio according to Rrs spectra is achieved at 547 nm in the spectral region of seawater with maximum transparency and low relative errors of measurements. The Rrs at 678 nm and associated products may be a significant characteristic for eddy detection if there are many phytoplankton in the eddy waters. The maximum depth of the remotely sensed contrast formation of the considered eddy vertical structure was ~6 m, which was significantly less than the maximum spectral penetration depth of solar radiation for remote sensing, which was in the 14–17 m range. The results obtained can be used to determine the characteristics that provide the best contrast for detecting eddy structures in remotely sensed reflectance data and to improve the interpretation of remote spectral ocean color data in the areas of eddies activity.

A novel loss function for neural network models exploring stock realized volatility using Wasserstein Distance

This study proposes a novel loss function for neural network models that explores the topological structure of stock realized volatility (RV) data by adding Wasserstein Distance (WD). The study shows that the proposed loss statistically significantly improves the forecast accuracy of neural network models for magnitude-dependent error measures, for example, Root Mean Square Error (RMSE) and Mean Absolute Error (MAE), but not necessarily for relative error measures, such as Quasi-likelihood (QLIKE). Additionally, this research provides user-friendly open-source code for researchers and practitioners to implement the proposed loss function efficiently and quickly.

An Adversarial Dual-Branch Network for Nonhomogeneous Dehazing in Tunnel Construction.

The tunnel construction area poses significant challenges for the use of vision technology due to the presence of nonhomogeneous haze fields and low-contrast targets. However, existing dehazing algorithms display weak generalization, leading to dehazing failures, incomplete dehazing, or color distortion in this scenario. Therefore, an adversarial dual-branch convolutional neural network (ADN) is proposed in this paper to deal with the above challenges. The ADN utilizes two branches of the knowledge transfer sub-network and the multi-scale dense residual sub-network to process the hazy image and then aggregate the channels. This input is then passed through a discriminator to judge true and false, motivating the network to improve performance. Additionally, a tunnel haze field simulation dataset (Tunnel-HAZE) is established based on the characteristics of nonhomogeneous dust distribution and artificial light sources in the tunnel. Comparative experiments with existing advanced dehazing algorithms indicate an improvement in both PSNR (Peak Signal-to-Noise Ratio) and SSIM (Structural Similarity) by 4.07 dB and 0.032 dB, respectively. Furthermore, a binocular measurement experiment conducted in a simulated tunnel environment demonstrated a reduction in the relative error of measurement results by 50.5% when compared to the haze image. The results demonstrate the effectiveness and application potential of the proposed method in tunnel construction.

Trace element composition of zircon from granitoids of the Neoarchean alkaline province of the Kola Peninsula

Research subject. Zircon from granitoids of the A- and I-types of the Neorchean Kola alkaline province of the Baltic (Fennoscandian) shield. Aim. To determine the trace element composition of zircon in order to characterize the conditions of its formation in different types of granitoids. To use these data, along with the available results of U-Pb dating and Lu-Hf isotope composition of the studied zircon crystals, to assess the amount of mantle and core matter in the protolith composition and the effect of crystallization conditions on the rare element composition of zircon. Materials and Methods. 50 zircon crystals from 5 samples of the main types of granitoids of the province were studied. Concentrations of trace elements were determined using a Cameca IMS-4f ion microprobe (NF FTIAN, Yaroslavl). Points for analysis were selected using optical and cathodoluminescent images. The size of the crater did not exceed 20 µm, the relative measurement error for the predominant part of the elements was set at 10–15%, the threshold for detecting elements was 10 ppb. Results. There are two main types of zircon of Neoarchean age – zircon-1 and zircon-2, formed, respectively, at the magmatic and autometasomatic stages of crystallization, zircon-4 in inclusions in zircon-1, and Paleoproterozoic zircon-3 of metamorphic genesis. The average isotopic composition of Hf in zircon-1 and zircon-2 of different arrays varies slightly, with the amount of mantle component (Xm) ranging from 23 to 30%, which may indicate a relatively constant and significantly core composition of their protoliths. Conclusions. The change in the trace element composition of Neoarchean zircons was controlled mainly by the composition of protoliths and redox crystallization conditions. Under reducing conditions, the greatest chemical activity was acquired by light (La-Nd) lanthanides, for which a direct dependence on the Ce/Ce* value was established. For heavy lanthanides with similar ion sizes relative to Zr+4, crystallochemical factors were more important and a decrease in the dependence of heavy lanthanide concentrations in zircon on Ce/ Ce* was determined.

Enhanced independent component analysis and fuzzy C-mean clustering based on novel bat algorithm for noisy image segmentation

Fuzzy c-means clustering is widely recognized as one of the most effective methods for image segmentation and achieving accurate classification. However, this method has two significant drawbacks: its sensitivity to noise and its convergence to local minimum clusters’ centroids. In this paper, we proposed a novel model called EIFCMNB, which incorporates enhanced independent component analysis (EICA), fuzzy c-means clustering (FCMC) and novel bat algorithm (NBA) for noise image segmentation. The suggested model consists of two main phases: image denoising and extraction of the regions of interest (ROIs). In the first phase, the enhanced independent component analysis (EICA) algorithm is used for recovering a good quality image, from a noisy image of poor quality. Several noisy images, with noise variances ranging from 5 to 20, were filtered. The resulting images were then evaluated based on several criteria viz: Peak Signal to Noise Ratio (PSNR), Relative Norm Error (RE), Normalized Cross-Correlation (NCC), and Structural Similarity index measure (SSIM). In the second phase, the fuzzy c-means clustering based on a novel bat algorithm is adopted to calculate optimal clusters’ centroids and extract the ROIs. By incorporating the new bat algorithm, we aim to overcome the problem of converging to local minimums and achieve improved segmentation accuracy. Promising experimental results have been obtained by applying the proposed model to MRI brain images and x-ray welding images. Two criteria viz: VPE end VPC have been employed to evaluate the suggested approach. The experiments clearly demonstrate that our suggested model effectively addresses the sensitivity to noise problem and provides optimal clusters’ centroids. Moreover, it outperforms several FCMC-based algorithms, exhibiting superior performance in terms of image segmentation and classification.

Laser absorption tomography of complex combustion fields based on finite element node strategy and adaptive edge optimization algorithm

Laser absorption spectroscopy tomography is a technique for combustion diagnosis that provides two-dimensional temperature and species concentration measurements. However, its current implementation assumes a homogeneous distribution of discrete grids, introducing errors and uncertainties in the reconstruction results due to large gradients between adjacent grids and information loss within a grid. This work aims to develop a finite element node strategy (FES) to address these issues. To enhance the reconstruction performance, we propose an adaptive edge optimization algorithm (AEO) that can effectively reduce artifacts and preserve edges. We validate the effectiveness of the algorithm through comprehensive simulations and experiments. The simulation results show that the error of integrated projection value exhibits a trend of rise with increasing resolution, and it is also true that the more complex the reconstruction distribution is, the larger the error becomes. In the simulation, the maximum relative error by using the discrete grids strategy (DGS) reached 1.3 % for complex distribution, whilst it was only 0.1 % when the FES was used. Two representative flame phantoms were used in the simulation. The reconstruction error of 4.51 % was achieved in one phantom by using the FES over 5.11 % for using DGS, in the other phantom, the error was 3.14 % for the FES compared with 3.88 % for the DGS. With the addition of the adaptive edge optimization algorithm (FES-AEO), the temperature reconstruction errors were reduced to 1.49 % and 1.77 % respectively, and the characteristic peaks and edge values were closer to the true values. The experimental results show that when the resolution is 1.67 mm, the mean relative error of the DGS measurements is 1.26 %, while the FES-AEO is only 0.65 %.

Multi-longitudinal-mode Doppler lidar technology based on quadri-channel Mach–Zehnder interferometer

The detection principle of a multi-longitudinal-mode (MLM) Doppler lidar based on a quadri-channel Mach–Zehnder interferometer (QMZI) was analysed. The measurement error formulas for the radial wind speed and backscatter ratio of this type of Doppler lidar system were derived. The advantages of this detection technology were thoroughly analysed based on the principle. The optical path difference (OPD) ‘l’ between the two interference arms of the QMZI was optimised. For a detection height of 0–20 km, ‘l’ was selected as 50 cm to balance the detection of radial wind speed and backscatter ratio. The overall structure of the MLM Doppler lidar based on QMZI was designed, and detailed design parameters of the system were provided. Further simulation was conducted to evaluate the detection performance of the designed QMZI- based MLM Doppler lidar system. The simulation results showed that when using a pulse laser with a power of 17.5 W@355 nm and a telescope with an aperture of 25 cm, a detection zenith angle of 30°, a vertical resolution of 26 m@0–10 km and 52 m@10–20 km and a pulse accumulation time of 1 min, the radial wind speed measurement errors of the system during the day and night were less than 2.1 m/s and 2.5 m/s; the backscatter ratio relative measurement errors were less than 0.81% and 0.97%.

Reliability Estimation of the Compressive Concrete Strength Based on Non-Destructive Tests

The uncertainty in the concrete compressive strength is one of the most challenging issues in safety checking of existing reinforced concrete (RC) buildings. The concrete compressive strength used in the assessment can highly influence the vulnerability results and thus the retrofit strategies. The need to use less expensive and less invasive in situ measurements such as the non-destructive tests should be balanced with a careful check of their structural reliability. The compressive concrete strength is characterized herein based on a large database of both in situ destructive and non-destructive results measured on the same structural members. The data are obtained from existing RC buildings mainly located in the Campania region, Southern Italy. Probabilistic linear and multilinear regression models are developed for calculating the compressive concrete strength based on non-destructive tests. Furthermore, the implementation of the concrete strength based on ultrasonic test results are investigated together with the relative measurement error through a fully probabilistic workflow. Accordingly, the relative weights of non-destructive data for calculating concrete compressive strength are estimated and compared with those recommended by the Italian national code. The results demonstrate that the effective weights of the non-destructive data are very close to the code-based recommendation.

Protocol Establishment and Reliability Verification of Three-Dimensional Digital Stereophotogrammetry in Lower Eyelid Anthropometry.

Three-dimensional (3D) stereophotogrammetry has been widely used in anthropometry for both medical and esthetic purposes. However, no studies have assessed its reliability on measuring the lower eyelid by 3D imaging. This study aimed to establish a standardized 3D anthropometric protocol for lower eyelid region and validate its reliability. Fifty-eight participants (116 eyes) were recruited with mean age of 39.14 ± 11.25 years. Two sets of VECTRA 3D images were taken for each subject, and each set of images was individually measured twice by two raters. Twenty-seven landmarks were identified in the lower eyelid region, and then 19 linear, 4 curvilinear, 7 angular and 2 areal metrics were assessed for intrarater, interrater and intramethod reliability. High reliability was found in this 3D imaging-based lower eyelid anthropometry. The mean absolute difference within 2 intrarater measurement were 0.22 and 0.08 units, the technical errors measurement were 0.31 and 0.15 units, the relative errors of measurement were 0.90% and 0.31%, the relative technical errors of measurement were 1.53% and 0.64%, and the intra-group correlation coefficient was 0.99 and 0.99. The results for interrater measurement were 0.53 units, 0.59 units, 2.94%, 3.41% and 0.96, and for intramethod measurement were 0.71 units, 0.77 units, 4.12%, 4.05% and 0.95 units, respectively. 3D stereophotogrammetry is reliable for lower eyelid anthropometry. The standardized protocol can be further applied for many purposes such as lower eyelid aging evaluation, surgical related assessment and periocular rejuvenation plan. This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Impact of anthropometry training and feasibility of 3D imaging on anthropometry data quality among children under five years in a postmortem setting.

The Child Health and Mortality Prevention Surveillance Network (CHAMPS) identifies causes of under-5 mortality in high mortality countries. To address challenges in postmortem nutritional assessment, we evaluated the impact of anthropometry training and the feasibility of 3D imaging on data quality within the CHAMPS Kenya site. Staff were trained using World Health Organization (WHO)-recommended manual anthropometry equipment and novel 3D imaging methods to collect postmortem measurements. Following training, 76 deceased children were measured in duplicate and were compared to measurements of 75 pre-training deceased children. Outcomes included measures of data quality (standard deviations of anthropometric indices and digit preference scores (DPS)), precision (absolute and relative technical errors of measurement, TEMs or rTEMs), and accuracy (Bland-Altman plots). WHO growth standards were used to produce anthropometric indices. Post-training surveys and in-depth interviews collected qualitative feedback on measurer experience with performing manual anthropometry and ease of using 3D imaging software. Manual anthropometry data quality improved after training, as indicated by DPS. Standard deviations of anthropometric indices exceeded limits for high data quality when using the WHO growth standards. Reliability of measurements post-training was high as indicated by rTEMs below 1.5%. 3D imaging was highly correlated with manual measurements; however, on average 3D scans overestimated length and head circumference by 1.61 cm and 2.27 cm, respectively. Site staff preferred manual anthropometry to 3D imaging, as the imaging technology required adequate lighting and additional considerations when performing the measurements. Manual anthropometry was feasible and reliable postmortem in the presence of rigor mortis. 3D imaging may be an accurate alternative to manual anthropometry, but technology adjustments are needed to ensure accuracy and usability.

Horizontal Deformation Monitoring of Concrete Pile with FRP-Packaged Distributed Optical-Fibre Sensors

Horizontal deformation is a key parameter in the structural assessment of concrete piles, especially in landslide cases. However, the existing deformation-monitoring methods cannot satisfy the demands of long-term monitoring. Therefore, a new method based on distributed optical-fibre sensing technology is proposed for the long-term monitoring of the horizontal deformation of concrete piles. First, a distributed long-gauge optical-fibre sensor is embedded into a fibre-reinforced polymer (FRP) for the excellent distributed strain measurement of the concrete piles in damage cases, such as concrete cracking and reinforcement yielding. Second, based on the typical Winkler beam model, a calculation theory can be constructed for the horizontal deformation of the concrete piles with the input of the strain measurement. Lastly, the proposed method is verified via finite element simulation and static experiments in a laboratory, and the results show good accuracy. Before the case of reinforcement yielding, the largest measurement error of deformation is about 1 mm. It can be up to several millimetres after reinforcement yielding due to the large gap between the calculation model and the actual structure, while the relative measurement error is only about 10%. Due to the distributed strain measurement, the inside horizontal deformation distribution of the concrete piles can be monitored online with the proposed method to implement a detailed assessment of the pile health. Additionally, considering the excellent long-term performance of FRPs and optical-fibre sensors, the proposed method can be applied for the long-term deformation monitoring of concrete piles.

Optimal Orientation Angle Configuration of Polarizers Exists in a 3 × 3 Mueller Matrix Polarimeter

A 3 × 3 Mueller matrix polarimeter, as one of the primary polarization measurement tools, has attracted intensive interest in various fields of polarization optics. In this paper, from a novel viewpoint with more mathematical analysis of the basic configuration and the working performance of a 3 × 3 Mueller matrix polarimeter, we systematically study the relationship between Mueller matrix measurement errors with the configuration and characteristics of polarizers in the polarimeter. We figure out that, mathematically, there is an optimal orientation angle configuration (0°, 60°, and 120°) of polarizers, which inherently ensures a minimal relative measurement error in general. Moreover, we interpret the internal source of such a robust error resistance under this optimized configuration mathematically for the first time. Simulation and practical experiments show the effectiveness of our mathematical analyses, and compared to the frequently used orientation angle configuration, the average relative error is reduced by up to 32% under such an optimized configuration.

Approach to multispectral thermometry with Planck formula and hybrid metaheuristic optimization algorithm.

Accurate temperature measurement has significant implications for product quality, industrial process control, and scientific research. As a non-contact temperature measurement method with broad application prospects, multispectral thermometry still poses significant challenges in data processing. Currently, most multispectral thermometry methods use the Wien approximation equation to construct the objective function. However, the use of the Wien approximation equation is conditional and generally applicable only to low temperatures or short wavelengths. In this paper, what we believe is a new data processing model of multispectral thermometry is established based on the Planck formula; Additionally, a feasible region constraint method is proposed to constrain the emissivity range; By utilizing a hybrid metaheuristic optimization algorithm based on differential evolution (DE) and multi-population genetic (MPG) algorithms, the simulation results of six different models and experimental results of silicon carbide demonstrate that the proposed algorithm achieves an average relative error in temperature measurement within 0.42% and a random relative error within 0.79%. The average computation time for each temperature inversion is approximately 0.26 seconds. The accuracy and efficiency of the algorithm ensure that it can be applied to real-time temperature measurement in industrial field.

Metal film thickness measurement using phase linearity feature for immunity to lift-off effect

In eddy current (EC) thickness measurements, the presence of the lift-off effect will significantly impact the measurement signal, leading to inaccuracies. It has been reported that the phase signal demonstrates a certain level of immunity to the lift-off effect compared to the amplitude signal, as its variation in response to lift-off is relatively less prominent. However, it should be noted that the phase is not entirely unaffected by the lift-off effect. In this paper, a linear relationship between the tangent of the phase angle and the lift-off has been found, termed the phase linear feature. Firstly, the phase linear feature was validated through theoretical derivations and experimental investigations. Subsequently, a new method of thickness measurement based on the fixed lift-off deviation was proposed by using this feature, and a corresponding double-coil sensor was also designed. Finally, to validate the proposed method, measurements of aluminum and copper films were carried out using the developed measurement system under different lift-off distances. The experimental results demonstrate that the measurement relative error of the proposed method remains within 5% in the 0–3 mm lift-off range. This indicates that the proposed method can provide accurate thickness measurements and is independent of the lift effect. Furthermore, the proposed method also has the advantages of single-frequency excitation, simplicity of the sensor, and straightforward relationship between features and thickness. Therefore, this study presents an effective solution for practical online thickness measurement.

A multiline fitting method for measuring ethylene concentration based on WMS-2f/1f

Coal spontaneous combustion risk assessment is a global technical challenge for the sustainable development of deep mining technology, and C2H4 is a key indicator for early warning of coal spontaneous combustion. Tunable diode laser absorption spectroscopy (TDLAS) has the advantages of high selectivity, high sensitivity, high accuracy and real-time on-line measurement, and it can detect multiple gases simultaneously, so it has significant advantages in the accurate detection of coal spontaneous combustion indicator gases. To address the problem of cross-interference between the near-infrared absorption lines of CH4 and C2H4, which are the indicator gases of spontaneous combustion in coal, a multi-line fitting method was proposed in this study to calibrate the concentration of C2H4. The high-precision Environics2000 automatic standard gas dispenser from the United States, which has a built-in CPU computer control and data control and processing system, was used. Its gas concentration accuracy: ± 1.0%, gas flow accuracy: ± 1.0%, gas repeatability accuracy: ± 1.0%, flow linearity accuracy: ± 0.5%, and inlet operating pressure: minimum 10 psig (0.67 bar) ~ 75 psig (5.04 bar). The measured and simulated WMS-2f/1f signals were multilinearly fitted using a multilinear fitting algorithm and wavelength modulation spectroscopy (WMS), and the measurement of C2H4 concentration was achieved based on the extracted spectral line information. The results show that the maximum relative error of C2H4 concentration measurement is 2.40%, which is 54% lower than that of the conventional 2f peak measurement method, thus demonstrating the effectiveness of the multilinear fitting algorithm in the inversion of C2H4 concentration under the interference of absorption lines. In addition, this study has far-reaching implications for the application of TDLAS technology in the accurate detection of coal spontaneous combustion indicator gases.