查看更多>>摘要：? 2022 Elsevier LtdThis paper presents the procedure for the extended calibration of temperature sensors (ECTS) based on the upper bound of dynamic error (UBDE) defined by the integral-square criterion. The proposed procedure is used for the extended calibration of the platinum resistance temperature detector (RTD) and negative temperature coefficient (NTC) temperature sensors. The approach proposed in the paper can be the basis for defining the dynamic accuracy class for the temperature sensors. Therefore, it shows an advantage over the classic method intended for calibrating this type of sensors. Procedure developed in the paper uses the Monte Carlo (MC) method and the fixed point algorithm (FPA) and genetic algorithm (GA). The validation of the obtained results is performed for the first type of sensor and for the ICT sensor. The solutions presented in the paper can be used to compare the UBDEs obtained for different types of temperature sensors.
查看更多>>摘要：? 2022 Elsevier LtdThe paper describes a new interpolated discrete Fourier transform (IpDFT) method for the frequency estimation of the real sine wave distorted by harmonics. The method complements recent work on the direct-formula IpDFT methods by expanding the model of the signal included in the interpolation. Spectral superposition for a total of four frequency components is accounted for in a one-step formula. Alongside the positive and negative components of the fundamental frequency, the influence from the closest low-order real harmonic is eliminated. By using the generalized maximum sidelobe decay (GMSD) window family, the interference from more distant harmonics and interharmonics is suppressed. This approach allows us to perform the measurement with a shortened data record compared to previous methods and improves accuracy in the case that a second-order harmonic is present in the signal. The study provides a five-point analytical, one-step formula that is verified by simulations and experiments in terms of accuracy and complexity. The experimental results are presented featuring straightforward C implementation on the system with an affordable microcontroller.
查看更多>>摘要：? 2022 The Author(s)Modifications of integrated calibration method (ICM) in its basic variant and complementary dilution method version (CDM) were adapted to multi-component (MC) analysis to obtain novel calibration approaches improving the accuracy of analytical results. Methods were developed conceptually and their performance was assessed on the basis of polycyclic aromatic hydrocarbons (PAHs) determination in air samples. The natural (thuja needles) and synthetic (polymer) materials were combusted simulating fires or home users’ combustion. Analytical method for determination EPA PAHs was developed using HPLC-DAD-FLD. It has been confirmed that the improved analytical results accuracy obtained in MC-ICM and MC-ICM/CDM was described by relative error < 1.5%. Multiplicative effects due to the coelution of other substances were detected by comparing the individual estimations of the analytical results. The results free from this effect were determined. According to RGB Additive Color Model, the proposed approach is White – method is a good candidate of choice for all applications.
查看更多>>摘要：? 2022 Elsevier LtdRockburst disasters seriously threaten the safety of deep coal mining. Electromagnetic radiation (EMR) is a powerful means of rockburst monitoring and early warning. However, the current related research often ignores the fact that the rock mass in engineering is frequently in a water-bearing state. Therefore, in this paper, the EMR signals of sandstone samples with different water contents were monitored under uniaxial compression. The experimental results showed that with the increase of water content, the EMR signals of sandstone weakened as well as the mechanical strength. Compared with dry samples, the total EMR energy and peak EMR energy of saturated samples decreased by 71.41% and 76.06% respectively. Moreover, higher moisture content would lead to lower dominant frequency and amplitude of EMR signals under various stress levels. Through multi-fractal analysis, it is found that with the rise of moisture content, the non-uniformity of signal (Δα) and the frequency diversity of minimum and maximum signals (Δf) decreased. These reflect some changes in the generation mechanism of EMR signal. The abrupt changes of Δα and Δf can be regarded as precursors of rock failure. The research results can provide guidance for the frequency band selection and precursor identification of rockburst monitored by EMR.
查看更多>>摘要：? 2022 Elsevier LtdThe traditional drill core sampling method used for pavement thickness detection is increasingly difficult to meet the increasing demand for pavement detection. At the same time, ground penetrating radar (GPR) have shown superiority in pavement non-destructive detection for its fast detection, safety and high efficiency. In this study, the traditional Canny algorithm was improved by combining wavelet denoising, intercept method and artificial bee colony algorithm, and the improved Canny algorithm was compared with the traditional Canny algorithm and connected region detection algorithm by combining simulated images and actual images. The detection results showed that the improved Canny algorithm had better performance, and the relative error was about 3.82%, which can realize the fast and intelligent detection of asphalt pavement thickness.
查看更多>>摘要：? 2022 Elsevier LtdIn the aircraft manufacturing industry, drilling hole inspection is a vital task for the noise reduction ability and the aircraft structure stability. Due to the complexity of the inner surface of the engine nacelle, inspecting drilling holes of a small size and a large number is fairly challenging. In this paper, we propose a framework for automatic hole inspection on composite flat parts. The raw data of traditional 3D laser scanning usually contain considerable noise and outliers, which has a great influence on tiny hole inspection. First, to perform measurement efficiently and to get raw data of good quality, we design a measurement platform to perform automatic measurement on a preset path. Instead of applying common boundary detection methods, we design a method to detect boundary points by evaluating the boundary possibility of each point, which is more likely to detect the points on a real hole boundary than noise. Based on the characteristics of laser scanning data, we then combine an effective algebraic circle fitting method with an iterative fitting strategy and develop a robust circle fitting method. The improved circle fitting method is capable of estimating a circle closest to the ground truth. Experiments demonstrate that our fitting method performs better than other common fitting methods for comparison under both synthetic and real scanning data.
查看更多>>摘要：? 2022The nonlinear characteristics of some flowmeters must be corrected so as to ensure the measurement accuracy. But the non-linearity correction may change the repeatability error between parameters, which makes the accuracy of the flowmeters fail to meet the requirements. This problem is rarely studied, but it is a basic problem. Therefore, variation of repeatability error in the non-linearity correction is deduced from the perspective of nonlinear characteristic function of the input and output. It is verified by the calibration and verification experiments of a constant-temperature-differential thermal mass flowmeter (CTDTMF). In order to facilitate engineering application, the judgment methods of piecewise linearity and relative variations of input and output are proposed, respectively, so as to quickly determine the numerical range of magnification.
查看更多>>摘要：? 2022 Elsevier LtdInspection the delamination of composite components is essential to ensure the safety of aircraft in service. Vision inspection has great potential for the drilling quality inspection of large composite components. However, stable extraction and accurate quantification of delamination are extremely challenging, due to the characteristics of low contrast, varying morphology, and random distribution of delamination. To address this problem, robust delamination extraction algorithm and integrated evaluation method are proposed. The extraction of delamination is achieved by contour extraction, robust circle fitting, and adaptive threshold segmentation. Based on this, the statistical quality description factor Qd-s is designed to quantify multi-dimensional information of delamination. Finally, the effectiveness of the proposed method is demonstrated. The experimental result shows that the proposed method outperforms traditional methods, which is expected to become a general technique for the inspection of delamination in the manufacturing process of CFRP.
查看更多>>摘要：? 2022 Elsevier LtdTo make correct judgment on the mixed faults of intershaft bearing of aeroplane engine, the paper has proposed a feature option method. This method works by decomposing cross-correlation function (CCF) of homogeneous information from casing with intrinsic time scale decomposition (ITD) for the separation and blending of signals. Furthermore, option of proper rotation components (PRCs) for fault identification is made by abandoning the PRC related with the least Complexity parameter in Hjorth parameters. Moreover, signal is reconstructed based on the autocorrelation function (AF) of residual PRCs. Finally, according to the frequency spectrum of signal reconstructed, fault features corresponding to intershaft bearing are extracted and fault types estimated. The result indicates that the Complexity parameter in Hjorth parameter can be used as an evaluation index to implement the selecting of sensitive fault components. Furthermore, the mixed fault types which come from intershaft bearing of aeroplane engine could be judged correctly.
查看更多>>摘要：? 2022 Elsevier LtdThis paper studies one of the major failures, that may occur in macro-scale strain gauge pressure sensors as well as micro-scale ones. The leakage in the interface fluid chamber of the sensor causes the air to be trapped especially in the form of bubbles in the interface liquid near the boundaries. In this work, mathematical modeling of a strain gauge pressure sensor in the presence of the trapped micro-scale bubbles in the interface liquid is presented. The governing equations of displacement of the membrane and sensing plate coupled with the nonlinear dynamic equation of bubbles are solved simultaneously utilizing the Galerkin weighted residual method. The transient response of the sensor in the presence of bubbles is investigated considering different types of applied dynamic pressure as step, single pulse, repetitive pulse, and harmonic. Results indicate that when a higher percentage of the interface oil is filled with bubbles, the maximum overshoot in the response of the sensor reduces, while, the peak time, rise time, and also settling time in the response of the sensor increases. A delay is observed in the time-domain response of the sensor due to the reduction of speed of transferring data from the membrane to the sensing plate caused by the bubbles in the interface liquid.
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