Measurement Principle Research Articles

Drift compensation system of an autocollimator based on reciprocal roll angles and a feedback combination target

To address the issues of limited field of view and beam drift in traditional autocollimation measurements, a novel, to our knowledge, autocollimation measurement method is proposed. This method is based on the principle of full-circle continuous measurement using reciprocal roll angles of a compound biaxial system, combined with a feedback and compensation mechanism for beam drift using both calibration and compensation targets. A self-collimating small-angle measurement system model, coupled with a compound biaxial turntable and combined target, is established using ray tracing and perspective projection transformation techniques. Additionally, a closed-loop beam drift compensation system is developed by applying a BP neural network and a PID control algorithm. Experimental tests on the compensation system demonstrate a significant improvement in measurement accuracy and stability. The results show that this method satisfies the requirements for small-angle autocollimation measurement, and the method also enhances the overall stability of the autocollimation system.

GGR Handbook of Rock and Mineral Analysis Chapter 13 Laser‐Induced Breakdown Spectroscopy (LIBS)

This chapter (Laser‐Induced Breakdown Spectroscopy (LIBS)) is a contribution to the Geostandards and Geoanalytical Research Handbook of Rock and Mineral Analysis – an online textbook that is a fully revised and updated edition of A Handbook of Silicate Rock Analysis (P. J. Potts, 1987, Blackie, Glasgow).Chapter 13 (from Section 3 of the handbook dealing with microbeam techniques) provides first a history of the development of laser‐induced breakdown spectroscopy, and of the LIBS process, followed by an examination of the fundamental principles of LIBS and its instrumentation. Discussion is then provided on the preparation of sample material, LIBS matrix effects and signal processing. Different modes of compositional analysis that can be tackled by LIBS are described, including quantitative measurement (covering isotope measurements), compositional mapping, depth profiling and the determination of physical properties of geological materials. The recent tandem coupling of LIBS with laser ablation ICP‐MS instrumentation is explored. Finally, a suite of examples of LIBS analyses of silicate rocks and minerals is provided, demonstrating the utility of this measurement principle in rapid compositional assessment, detailed petrological studies and microgeochemical mapping.

High‐speed and contactless inspection of defective micro‐LEDs through the photovoltaic effect

AbstractThe most significant challenge associated with micro‐light‐emitting‐diode (micro‐LED) displays, which are anticipated to be the next generation of display technology, is the high manufacturing cost. In order to reduce manufacturing costs, it is essential to improve yield. Improving the manufacturing yield of them necessitates the evaluation of micro‐LED chips prior to their installation onto substrates. However, the microsize and large quantity of these chips renders inspection difficult with conventional inspection methods. Herein, we propose a method for inspecting micro‐LED chips by measuring the voltage generated between the anode and cathode due to the photovoltaic effect using a developed proximity capacitance image sensor. As this inspection method does not require the use of probe pins to contact LED electrodes, it enables simultaneous inspection of multiple chips in a short time without causing any damage to the electrodes. In this paper, an experimental system equipped with this sensor was developed to demonstrate the basic measurement principle. Moreover, we demonstrated that more than 50,000 micro‐LED chips with a size of 60 μm × 34 μm can be simultaneously inspected in approximately 2 s.

A NOVEL GOLD NANOPARTICLE‐IONIC LIQUID NANOSTRUCTURE MODIFIED Pleurotus Ostreatus BASED MICROBIAL BIOSENSOR SYSTEM FOR BISPHENOL A

The current study develops the first and novel gold nanoparticle‐ionic liquid nanostructure modified microbial biosensor based on <i>Pleurotus ostreatus</i> for the sensitive determination of Bisphenol A <b>. </b>In the construction of the microbial biosensor, lyophilized <i>P.ostreatus</i> cells were modified with ionic liquid‐cysteamine mixture on a gold electrode which was modified with 1,6‐hexanedithiol and gold nanoparticle. The measurement principle of the biosensor is based on the detection of changes in current in a phosphate buffer system (pH 7.5, 50 mM and containing 5.0 mM K <sub>3</sub>[Fe(CN) <sub>6</sub>]) in the potential range of ‐0.2 to +0.6 V depending o

Modeling of an inductive displacement sensor based on 1DCNN-LSTM-AT

Abstract The input-output relationship of inductive displacement sensors is typically nonlinear, which demands numerous computational resources for precise calculation. Therefore, the traditional analytical methods for the inductive displacement sensors cannot meet the real-time high-precision measurement requirements. In response to the aforementioned issues, this paper proposes an optimized Long Short-Term Memory (LSTM) neural networks based on one-dimensional convolutional neural networks (1DCNN) to modeling the input-output relationship of the inductive displacement sensor. First, the measurement principle of the inductive displacement sensors was analyzed, and the analytical model of the sensor output was derived. And the influences of the key parameters of sensors on the relationship between the induced voltage and the displacement were studied. Then, the 1DCNN-LSTM-AT network for modelling the input-output relationship of the inductive displacement sensor was studied. The spatial features of historical induced electromotive force (EMF) data generated by the induction coil were initially extracted using the 1DCNN network. And these spatial features were then utilized as input to the LSTM neural network to capture the temporal features of the historical induced EMF data. Subsequently, the spatiotemporal features of the induced EMF data were fed into the regression prediction layer to compute the displacement measurement results corresponding to the current input. Moreover, the attention mechanism was used for the 1DCNN-LSTM model to enhance the prediction accuracy and stability of the model. Finally, the experimental results demonstrate that the proposed 1DCNN-LSTM-AT model achieves an average absolute percentage error (MAPE) of 3.1%, significantly outperforming traditional models such as LSTM (29.3%), CNN (4.7%), and ANN (4.3%). This paper provides a new method for modelling the nonlinear relationships of the inductive displacement sensor, and presents a fresh perspective for research in the data processing of nonlinear sensors.

A Study of Data Processing Methods for Non-Contact Multispectral Method of Blood Oxygen Saturation.

Regular monitoring of blood oxygenation is important for disease prevention and treatment. Image photoplethysmography (IPPG) technology is a non-contact physiological parameter detection technology, which has been widely used in blood oxygenation detection. However, traditional imaging devices still have issues such as low detection accuracy, narrower receiving spectral range. In this paper, we proposed two improved detection methods based on the dual-wavelength measurement principle, that is, dual-band IPPG signal ratio method and dual-band IPPG signal AC/DC method. To verify the effectiveness of the two methods, we used different heartbeat period IPPG signals as sample data sets, and combined PLS and RF algorithms for model training, thus obtaining the best data processing method. The experimental results showed that the dual-band IPPG signal AC/DC method can effectively reduce the model training time. This method meets the strong demand for non-contact blood oxygen measurement and provides a new measurement idea.

Loaded tooth contact analysis for helical gears with surface waviness error

Meshing characteristics are crucial for the transmission performance of vibration noise and strength of gear systems. Gear transmission error has been acknowledged as a prominent excitation in vibration systems, but the surface waviness deviations that directly affect it in contact analysis are generally ignored. This study proposes a comprehensive model for quasi-static analysis of tooth surfaces with waviness error. The model reconstructs the actual tooth surface in reverse based on the gear Fourier measurement principle. Instead of solving the meshing equations to pre-assume contact position, the problem of normal contact between surfaces with deviations is solved by an innovative multiscale grid and a local iterative numerical algorithm. Combining the finite element numerical method and surface integral of the Boussinesq solution determines gear deformation and develops a loaded contact model. The validity of the model is verified through numerical examples. Furthermore, the proposed model is applied to discuss the tooth surfaces with different waviness amplitudes, frequencies, and distribution angles for the first time. It explains the interaction between local microscale and global scale introduced by waviness error on tooth surfaces and reveals the mechanism of the waviness error on meshing performance.

Environmental challenges and economic cooperation between Ukraine and the EU: prospects for sustainable development

The article is dedicated to analyzing the cooperation between Ukraine and the European Union, which began with the signing of the Partnership and Cooperation Agreement in 1994 and reached a new level after the signing of the Association Agreement in 2014. The focus is on the impact of this agreement on Ukraine’s domestic and foreign policies, particularly in the context of sustainable development and ensuring environmental security. The article examines the role of international agreements in regulating Ukraine’s environmental policy, particularly the principles of preventive measures and the use of natural resources within the framework of sustainable development. Despite the formal incorporation of relevant provisions in international treaties, the real situation regarding environmental security remains challenging due to the conflict between the economic interests of developed countries and transnational corporations and the demands of environmental protection. The article separately addresses the influence of international law on the development of Ukraine’s energy policy and its integration into the pan-European energy space. The importance of transitioning to renewable energy sources and the role of the European Union in financing and supporting such projects are analyzed. It is noted that sustainable development and environmental protection should become priorities within the framework of Ukraine’s energy security policy. The article also outlines the main challenges Ukraine faces in the context of international environmental security, particularly the insufficient effectiveness of international organizations in recognizing and counteracting environmental crimes. Despite this, the importance of cooperation with the EU to achieve a stable deceleration of environmental degradation is emphasized.

Symmetry Breaking and Modal Localization in a System of Parametrically Excited Microbeam Resonators

In this work, we study the nonlinear dynamics of parametrically excited bending vibrations of two weakly coupled beam microresonators under electrothermal excitation. A steady-state harmonic temperature distribution in the volume of the resonators in the frequency domain was obtained. A system of equations for mechanically coupled beam resonators is derived, considering the deposited particle on one of them. Using asymptotic methods of nonlinear dynamics, equations in slow variables were obtained, which were studied by methods of the theory of bifurcations. It is shown that in a perfectly symmetrical system in a certain frequency range, the effect of symmetry breaking is observed – the emergence of a mode with different amplitudes of oscillations of two beam resonators, which can be the basis for a new principle of high-precision measurements of weak disturbances of various physical natures, in particular – measurements of ultra-low masses of deposited particles.

Principles and prospects of Bose-Einstein correlation study at BESIII* *This study was supported by the National Key R&D Program of China (2020YFA0406403) and the National Natural Science Foundation of China (11275211, 11335008, 12035013)

One method for determining the characteristic parameters of a hadron production source is to measure the Bose-Einstein correlation functions. In this study, we present fundamental concepts and formulas related to the Bose-Einstein correlations, focusing on the measurement principles and the Lund model from an experimental perspective. We perform Monte Carlo simulations using the Lund model generator in the 2–3 GeV energy range. Through these feasibility studies, we identify key features of the Bose-Einstein correlations that offer valuable insights for experimental measurements. Utilizing data samples collected at BESIII, we perform measurements of the Bose-Einstein correlation functions, with an expected experimental precision of a few percent for the hadron source radius and incoherence parameter.

Research on optimization of mining methods for broken ore bodies based on interval-valued pythagorean fuzzy sets and TOPSIS-GRA.

Identifying the optimal mining methods plays a pivotal role in ensuring both economic efficiency and environmental sustainability. This study aims to propose a model that combines interval-valued Pythagorean fuzzy sets (IVPFS) and TOPSIS-GRA to select the optimal mining method for broken ore bodies. First, a multi-factor comprehensive evaluation system, including economic, safety, and technical aspects, was established. IVPFS was introduced to express the fuzzy information of the decision-making process within the evaluation system. Additionally, an objective method combining the principle of fuzzy entropy measurement with EWM was proposed to determine the weights of fuzzy information. This method distinguished the importance of decision-makers and indicators. Then, an integration of distance and similarity (TOPSIS-GRA) was employed for ranking alternative solutions to select the optimal one. This model was applied to the decision-making problem of mining methods for the broken and difficult-to-mine ore bodies in the Tanyaokou mining area. Initial fuzzy evaluation information was obtained by having decision-makers score the mining methods. Results showed that the comprehensive scores of four alternatives are 0.5172, 0.4683, 0.5192, and 0.5465, respectively. The optimal method was the point-pillar upward horizontal layered filling mining method. Finally, the sensitivity analysis confirmed the stability of the model. The comparative results under different fuzzy environments (PFS and TFS) demonstrated the strong capability of IVPFS in handling fuzzy information for optimizing mining methods.

Rotaphone-D, A New Model of Six-Degree-of-Freedom Seismic Sensor: Description and Performance

Abstract A new model of the Rotaphone-D short-period seismic sensor with six degrees of freedom is introduced. The basis of the instrument is horizontal and vertical geophones in a special paired arrangement. The instrument is designed for simultaneous and collocated measurements of rotational and translational components of ground motion. The basic principle of measurement is briefly described. Careful calibration is necessary for this type of measurement, which has two parts: a preliminary calibration based on laboratory measurements of the characteristics of the individual geophones, and a subsequent in situ calibration, which takes into account the actual physical conditions during field measurements and is performed during the processing of the measured data. The effect of the calibration is demonstrated by specific laboratory tests. The laboratory tests have confirmed the correct functioning of the instrument. The frequency range of Rotaphone-D is from 2 to 80 Hz and is therefore optimal for monitoring local seismicity. The instrument was subsequently used in field measurements during two several-month measurement campaigns in California, United States. Examples of six-component records from two sites—The Geysers and Long Valley Caldera—are presented and briefly interpreted from a seismological perspective. Basic instrument parameters are given. The instrument is lightweight, portable, easy to install, and offers several interesting applications, which are briefly discussed. Six-component measurements (translational and rotational) have become a powerful tool, especially in volcanic seismology and in monitoring induced seismicity.

Concept study of a storage ring-based gravitational wave observatory: Gravitational wave strain and synchrotron radiation noise

This work for the first time addresses the feasibility of measuring millihertz gravitational waves (mHz GWs) with a storage ring-based detector. While this overall challenge consists of several partial problems, here we focus solely on quantifying design limitations imposed by the kinetic energy and radiated power of circulating ions at relativistic velocities. We propose an experiment based on the measurement of the time-of-flight signal of an ion chain. One of the dominant noise sources inherent to the measurement principle for such a GW detector is the shot noise of the emitted synchrotron radiation. We compute the noise amplitude of arrival time signals obtained by analytical estimates and simulations of ions with different masses and velocities circulating in a storage ring with the circumference of the Large Hadron Collider. Thereby, we show that our experiment design could reduce the noise amplitude due to the synchrotron radiation in the frequency range 10−4–10−2 Hz to one or two orders of magnitude below the expected GW signals from of astrophysical sources, such as supermassive binary black holes or extreme mass-ratio inspirals. Other key requirements for building a working storage ring-based GW detector include the generation and acceleration of heavy ion chains with the required energy resolution, their injection and continued storage, as well as the detection method to be used for the determination of the particle arrival time. However, these are not the focus of the work presented here, in which we instead concentrate on the definition of a working principle in terms of ion type, kinetic energy, and ring design, which will later serve as a starting point when addressing a more complete experimental setup. Published by the American Physical Society 2024

Development of a high-fidelity digital twin using the discrete element method for a continuous direct compression process. Part 1. Calibration workflow

In this work, a high-fidelity digital twin was developed to support the design and testing of control strategies for drug product manufacturing via direct compression. The high-fidelity digital twin platform was based on typical pharmaceutical equipment, materials, and direct compression continuous processes. The paper describes in detail the material characterization, the Discrete Element Method (DEM) model and the DEM model parameter calibration approach and provides a comparison of the system’s response to the experimental results for stepwise changes in the API concentration at the mixer inlet. A calibration method for a cohesive DEM contact model parameter estimation was introduced. To assure a correct prediction for a wide range of processes, the calibration approach contained four characterization experiments using different stress states and different measurement principles, namely the bulk density test, compression with elastic recovery, the shear cell, and the rotating drum. To demonstrate the sensitivity of the DEM contact parameters to the process response, two powder characterization data sets with different powder flowability were applied. The results showed that the calibration method could differentiate between the different material batches of the same blend and that small-scale material characterization tests could be used to predict the residence time distribution in a continuous manufacturing process.

An SPR-Based In Situ Methane Sensor for the Aqueous and Gas Phase.

This paper presents a fast, low-cost, precise methane sensor based on refractive index changes in a cryptophane A (CryptA)-doped polystyrene membrane. For the realization of this sensor, we built a surface plasmon resonance sensor with a refractive index resolution of 4.31 × 10-6 and investigated the optimal membrane thickness, i.e., a polymer layer of sufficient sensitivity with the lowest response time. For a membrane thickness of 760 nm, a limit of detection of 135 ppm and a response time constant of 45 s were found. Despite a comparable refractive index resolution and a higher CryptA content, the limit of detection is 3 orders of magnitude larger than that of a reported prototype. The sensor is capable of quantifying methane in the gas or aqueous phase. However, temperature, humidity, and ethanol vapor highly influence the signal. Although the principle of CryptA-based methane measurement is a promising, fast, and low-cost method, it will not be able to compete with state-of-the-art sensing in its current state.

Modulation Measurement Profilometry Based on One-Dimensional Frequency-Guided S-Transform

Abstract The modulation measurement profilometry employs the principle of vertical measurement, where the projection optical axis and the observation optical axis are aligned. This technique effectively avoids the limitations of shadows and occlusions inherent in optical 3D sensing methods based on the triangulation principle. To further enhance the accuracy of modulation information extraction, a one-dimensional frequency-guided S-transform method (1D-FGST) is introduced, which incorporates the parameter p to control the width of the Gaussian window, offering better time-frequency analysis characteristics compared to the traditional one-dimensional S-transform method (1D-ST). It can extract high-frequency detailed information about object, achieving a root mean square (RMS) error of 4.24 μm within a depth range of 1100 μm.

An unconstrained and non-redundant identification method of geometric errors and compensation of machine tools by X-AX Laserbar

Efficient and accurate measurement and identification of geometric errors are crucial for improving the precision of CNC machine tools. The X-AX Laserbar, as a novel tool for indirect measurement, has not been extensively studied for the identification of geometric errors in machine tools. In this paper, the geometric error model for a three-axis machine tool is established to illustrate the multilateration measurement principle of the laserbar, and a non-redundant and unconstrained identification method is proposed to identify these geometric errors. This method avoids the use of redundant parameters and additional constraints by employing pose error twists to describe the geometric errors. These pose error twists are identified in a transitional coordinate system, and then the geometric errors will be identified in the machine coordinate system by deriving the relationship between the pose errors and geometric errors. The proposed method is validated with the VMC-850E three-axis machine tool. The geometric error measurement using a laserbar is completed in about 40 min, showing great efficiency. The experimental results indicate that the proposed method is capable of accurately identifying the 17 geometric errors required for error compensation. The identified geometric errors are then applied to the machine tool’s accuracy improvement through error compensation. The results show that the actual geometric errors are controlled to a low level. The proposed method can efficiently measure the geometric errors of three-axis machine tools and contribute significantly to improving their geometric accuracy.

Calibration modeling of drilling fluid rheological parameters in variable temperature environment based on support vector machine.

Traditional measurement of drilling fluid rheological parameters suffers from significant lag due to the inability of the instruments to promptly capture real-time parameters of the drilling fluid. These measurement models are typically constructed based on fixed temperature conditions and empirical formulas, rendering them inadequate for complex temperature gradient environments. Consequently, this limitation results in increased prediction errors, severely compromising the precise monitoring of drilling fluid performance. Aiming at the problems of low accuracy and poor stability of drilling fluid measurements under variable temperature conditions, a support vector machine-based calibration model for drilling fluid rheological parameters in a variable temperature environment is proposed in this paper. First, the measurement principle of the double-tube differential pressure rheology real-time measurement device is analyzed. The relationship between shear stress and shear rate is then established using differential pressure sensor and flow rate data. Utilizing the gray wolf optimization algorithm to optimize the kernel function weights and parameters, an SVM-based calibration model for predicting drilling fluid rheology correction parameters is constructed. Finally, a real-time monitoring platform for drilling fluid is developed. Experimental results show that the maximum relative errors for the predictions of apparent viscosity, plastic viscosity, and yield point are within ±5%, with coefficients of determination (R2) all greater than 0.95. These results validate the effectiveness of the proposed method in accurately monitoring the rheological performance of drilling fluids.

Extension of the displacement method by measuring reference pieces using multiple sensors for on-machine surface profile measurement

On-machine measurement is crucial in industrial production because it allows the measurement of the surface properties of products without having to remove them from the machine tool; however, measurement results are superimposed with the motion error caused by the table traverse. Therefore, eliminating motion errors is this field's main objective. This paper discusses measuring a surface profile using an extension of the displacement method to eliminate motion errors. The displacement method can separate the surface profile and motion error of the stages in measurement results; however, it introduces a specific cumulative error. The tolerance of the accumulated error was first investigated by simulating a one-axis measurement. The displacement method was extended to a two-axis stage to measure the surface profile and correct the stage tilt to each axis. Moreover, carbon steel finished using a face mill was measured in the experiments, and a coordinate measuring machine was used to compare the results with those of the extended displacement method. It was found that the extended displacement method was able to remove the motion error. Applying the displacement method resulted in an improvement of approximately 88.9%. Error analyses were also formulated and evaluated for sensor drift, reference piece measurement, motion error, table rotation, and thermal expansion, and the percentage of these errors in the total was clarified. The results showed that the motion error and table rotation for the y-axis of the prototype experimental apparatus were larger than the others. These errors are discussed to analyze each error and listed in the error budget. The proposed extended displacement method can eliminate motion errors despite the simplicity of the measurement principle and can be easily integrated into machine tools and other tables.

Inaccuracy principle and dissolution mechanism of lithium iron phosphate for selective lithium extraction from brines

The electrochemical lithiation/delithiation (ELD) method with the typical active materials being LiFePO4 and LiMn2O4, is the next generation technique for the selective lithium extraction from slat-lake brines owning to the advantages of high selectivity and excellent capacity and feasibility. However, the dissolution of LiFePO4/FePO4 (LFP/FP) during the ELD is seldom studied and an inaccurate measurement method for dissolution may result in obtaining an incorrect feasible application range for LFP/FP. Here, electrochemical workstation-electrochemical quartz crystal microbalance (EW-EQCM) is first utilized in the brine system to acquire the in-situ dissolution behavior of LFP/FP redox couple and verify the inaccuracy principle of the dissolution measurement. Both experimental results and thermodynamic calculations demonstrated that the accurate dissolution ratios can only be obtained by iron ions and phosphates at pH < 2.7 and pH < 5.3, respectively, which is induced by the narrow soluble range of iron ions and the formation of Ca5(PO4)3OH and Mg3(PO4)2 precipitation. In addition, the stable pH range of LFP and FP is 4 to 10 and 3 to 5, respectively, and the dissolution is caused by the formation of thermodynamically more stable metal ions, metal ion complexes, and metal ion hydroxides. At the optimum pH, the capacity can maintain 35 mg/g with average dissolution ratios of the cathode and anode lower than 0.1 %. This research sheds light on the accurate dissolution measurement range and method, dissolution mechanism and feasible application range of the LFP/FP redox couple.