查看更多>>摘要：? 2022 Elsevier LtdIn order to obtain more reliable wheel-rail contact force and improve the accuracy of wheel fault detection, a continuous wheel/rail force measuring method is investigated, and an indoor prototype is built for verification. The wheel/rail force is mainly measured by shear method, and the time of wheel entering and leaving the test area is measured by proximity switch at the same time. Then the measured discrete wheel/rail forces are connected together by computer editing. The calibration coefficients of the shear wheel/rail forces can be obtained by using a special calibration device which can move easily on the rails. The results show that the continuous wheel/rail force reproduced by using 14 measured discrete wheel/rail forces can cover the whole wheel running surface, and also can reflect the wheel surface defects. When the wheel defect such as wheel flat appears, the wheel/rail impact induced by wheel flat has a strong effect on the wheel/rail force. Thus the mapping relationship between the wheel flat and wheel/rail force can be established and be adopted to identify the length and depth of wheel flat.
查看更多>>摘要：? 2022The fault diagnosis of the wind turbine gearbox is of great significance for improving the safety of the unit operation and reducing the downtime. Therefore, aiming at the contradiction between diagnostic accuracy and complexity of diagnostic model in a noisy environment, this paper studies it and proposes Lightweight multivariate and multi-directional induction network (LM-MDINet). This method designs dense separable blocks (DS- Blocks) to enhance deep feature extraction. At the same time, by decoupling the mapping relationship between the space and the channel, the amounts of parameters are reduced. In addition, a multivariate and multi-directional induction (M-MDI) layer has been added to guide the network towards the expression of effective fault information to enhance the network's ability to learn effective information. The experimental results show that the proposed method has outstanding comprehensive performance in noisy environment to compare with other methods.
查看更多>>摘要：? 2022 Elsevier LtdThe deterioration state of planetary gearboxes with pitting faults cannot be diagnosed and evaluated effectively with a single type of monitoring signal and traditional features. In this study, a new diagnose method was proposed based on the tribology and vibration signal of planetary gear systems. A new feature extraction approach was exploited to construct a multi-feature fusion relevance vector machine (MFFRVM) model for diagnosing the deterioration state of planetary gearboxes. Meanwhile, a novel index for online wear debris monitoring (ADIDC) was extracted to evaluate the wear evolution of planetary gears. Condition monitoring experiments were conducted on a planetary gearbox. Experimental results show that the diagnostic method combining the MFFRVM model and ADIDC index achieves better accuracy than other methods. This study provides guidance for the wear evolution evaluation of planetary gears with pitting faults and the early fault recognition of planetary gearboxes.
查看更多>>摘要：? 2022 Elsevier LtdThe accurate and timely detection of anomalous conditions are essential for the safe and economical operation of complex thermal power plants (TPPs). However, the development of an excellent anomaly detection model without sufficient fault data is difficult in practice. In addition, global-based detection methods can submerge local anomalous behavior, causing serious delays in providing early warning of anomalous conditions. To solve this issue, a multiblock detection method based on the framework of evidence theory is proposed in this study. Measured variables collected from different units are automatically divided into several subblocks by using mutual information (MI)-based spectral clustering. Then, an evidential k-nearest neighbors algorithm (EKNN) is developed in each block, and local detection results are calculated. To provide an intuitionistic indication, the Dempster–Shafer rule is adopted to fuse the detection results of all the subblock EKNN models. The proposed approach can be applied to linear and nonlinear processes on the basis of MI and the nonparametric k-nearest neighbors procedure. To confirm its effectiveness, the proposed method is validated on samples collected from an ultra-supercritical TPP in China.
查看更多>>摘要：? 2022 Elsevier LtdLight field particle image velocimetry (LF-PIV) can measure three-dimensional (3D) flow velocity from a single snapshot of a light field camera based on the 3D reconstruction of tracer particles of light field images. However, it requires light field intensity calibrations to calculate accurate weight coefficients. Conventionally, the weight coefficients are calculated through in-situ calibration approaches whereas the translation of the calibration board within the entire measurement area is required. Therefore, these approaches are inapplicable for internal industrial flows and space-constrained applications. This study presents an equivalent ray tracing method for the weight coefficients calculation. With a light field snapshot of a smart calibration board, a mapping relationship is established to relate the target points sampled in the flow field with their equivalent points in the air. The weight coefficients are then calculated through the ray tracing method by changing the starting points of ray tracing from the target points to their equivalent points. The calculated weight coefficients are employed to reconstruct the feature marks of the calibration board. Results show that the spatial locations of the marks can be reconstructed accurately with a mean lateral and depth error of 0.63% and 5.6%, respectively. Experiments were also carried out on a low-speed laminar flow. The result indicates that the equivalent ray tracing method provides a similar measurement accuracy with the in-situ calibration method. The overall error of 6.77% is achieved for the velocity measurement. It is demonstrated that the proposed method is capable of measuring the 3D flow velocity for internal industrial and space-constrained applications without translating the calibration board within the entire measurement area.
查看更多>>摘要：? 2022 Elsevier LtdCopper particle has been detected among dominant aluminum particles by in-situ resistance background implemented in conductance-path recognition algorithm (iRB-CPR). The iRB is a particle volume fraction prediction from a resistance background database measured by shifted-four-wire measurement (SRM) in various particle arrangements. The CPR is adopted from a decision tree algorithm to predict the particle conductance path by comparing the real-condition resistances classified by iRB. The selected resistance background is used as a denominator to normalize the resistance measurement by SRM under unknown particle arrangement in the real condition. Finally, Cu is detected by comparing the normalized resistances with the normalized spatial-mean resistance. The iRB-CPR successfully suppress the resistance deviation ratio in the simulation 〈r〉sim 93.8% and experiment 〈r〉exp 73.9%. Moreover, the Cu detection by iRB-CPR satisfies give a low error ES = 6.11% at S = 180 under α = 10%. This research opens a new detection modality as a part of non-ferrous metal particles recovery.
查看更多>>摘要：? 2022 Elsevier LtdLocalized and distributed faults in machinery may lead to catastrophic failures of the high-speed rotor bearings. Unbalance and misalignment present generate massive vibrations in the rotor-bearing system. This paper demonstrates duo of the matrix method of dimensional analysis (MMDA) and support vector machine (SVM) to investigate unbalance and misalignment present in the rotor-bearing system. Experimentation with different conditions is performed and compared with numerical results to reveal the effectiveness of the approach. The SVM algorithm is used to classify multiple fault classes based on vibration characteristics predicted by the MMDA model. The results comparison shows that the present duo predicts and classifies the misalignment and unbalance with acceptable error and can be useful for industrial high-speed machine diagnosis.
查看更多>>摘要：? 2022 Elsevier LtdAnnulus liquid level depth is used to describe the variation of sustained casing pressure, calculate the leakage location, and reflect the hydrocarbon content in annulus. There are currently no theoretical prediction methods for it. Thus, a prediction model and numerical solution method for the annulus liquid level depth are established, and this model is then utilized to analyze the effects of various factors on the annulus liquid level depth. The research results show that the wellhead temperature, initial tubing-casing annulus pressure, and the amount of annulus gas released have a significant influence on the annulus liquid level depth by changing the annulus liquid compression and string deformation. The impact of a huge annular pressure change on the annulus liquid compression is noticeable, which is beneficial to improving the prediction accuracy of the annulus liquid level depth. Therefore, this prediction method is better suited to high-pressure wells than the echo-sounding method.
查看更多>>摘要：? 2022 Elsevier LtdThe source intensity of metro-induced vibrations is defined as the vertical weighted vibration acceleration level on a tunnel wall. It is traditionally determined using the empirical method or analogical test. However, recent research has indicated that tunnel vibration responses vary significantly according to the passing train, likely owing to the influence of wheels worn out-of-round. To analyse the associated uncertainty of the vibration source intensity, five monitoring tests were performed in a metro tunnel over the course of one year. Each test lasted 24 h, during which the vibration responses of all the passing trains were recorded. Then, information describing the operating mileage for all passing trains was collected to quantitatively analyse the relationship between the vibration source intensity and the wheel conditions. The results indicate that different trains can generate source intensities with significant differences greater than 10 dB in most 1/3 octave bands between 40 and 315 Hz. The tunnel vibration responses increased with the net operating mileage of the passing trains, and the vibrations between 40 and 315 Hz decreased by more than 20 dB after wheel re-profiling. The maximum and average values of the tunnel vibration responses decreased by 8 and 5 dB, respectively, after rail grinding.
查看更多>>摘要：? 2022 Elsevier LtdThe excess level of hypochlorite may pose a significant problem for living organisms and environment. Therefore, the development of sensitive, reliable and facile-to-apply sensing molecules for hypochlorite detection is essential. The present work reports a novel antharacene-modified isophorone (IMA) fluorescent sensor as a detecting material for toxic and corrosive hypochlorite. IMA demonstrates excellent selectivity toward hypochlorite over other competing analytes through a distinct fluorescence signal change from red to purple. Detection mechanism proceeds via oxidation reaction of the probe by hypochlorite releasing the fluorescent 9-aminomethlyanthracene unit as verified by TOF-MS, 1H NMR and IR spectra. The experimental results demonstrate that IMA has excellent sensitivity, low detection limit (0.29 μM), fast response time and high pH stability for hypochlorite. By employing IMA on a TLC test kit and in real samples, the hypochlorite level is successfully determined. Moreover, IMA allowed the fluorescence bioimaging of hypochlorite ions in yeast cells.
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