查看更多>>摘要：The rail under high pressure work will grow damage. In the high-speed railway, defects development initially manifests as opening diagonal defects on the surface and buried defects near surface of the rail, and the existing non-destructive testing (NDT) methods find it difficult to achieve comprehensive detection and assessment of rail surface and near surface defects. This paper proposes a multi-frequency excitation composited electromagnetic detection based on different detection characteristic of the system, which can be used to achieve comprehensive assessment of rail surface and near-surface defects. A high-speed rail experimental system is designed to implement experimental analysis which finds that the system can effectively improve the accuracy, anti interference and stability of surface defect assessment, and realize the quantitative assessment of buried defects. And the multi-frequency composited electromagnetic detection method can also suppress the attenuation of eddy current signal at high speed and improve the signal-to-noise ratio.
查看更多>>摘要：Magnetic sensing platform techniques have been used in many years in an attempt to better evaluate the likelihood of recoverable hydrocarbon reservoirs by determining the depth and pattern of sedimentary rock formations containing magnetic minerals, such as magnetite. Utilizing airplanes, large-area magnetic surveys have been conducted to estimate, for example, the depth of igneous rock and the thickness of sedimentary rock formations. In this case, the vector magnetic survey method can simultaneously obtain the modulus and direction information of the Earth's magnetic field, which can effectively reduce the multiplicity on data inversion, contribute to the quantitative interpretation of the magnetic body and obtain more precise information and characteristics of magnetic field resource, so as to improve the detection resolution and positioning accuracy of the underground target body. This paper presents a state-of-the-art review of the application situations, the technical features, and the development of the vector magnetic sensing platform technical aspects for different application scenarios, i.e., ground, wells, marine, airborne, and satellites, respectively. The potential of multi-survey sensing platform technique fusion for magnetic field detection is also discussed.
Gupta, Munish KumarBoy, MehmetKorkmaz, Mehmet ErdiYasar, Nafiz...
14页
查看更多>>摘要：In this work, the sustainable machining approach is promoted by implementing the dry and minimum quantity lubrication (MQL) cooling conditions in the turning of duplex stainless steel. Initially, the turning experiments were performed under dry as well as MQL conditions and then, the influence of different positions of MQL nozzles on tribological and machining performance of 2205 duplex steel was investigated. The cutting parameters were kept fixed and the performance is evaluated in terms of surface roughness, micro-hardness, energy consumption, tool wear, machined surface microstructure and chips morphology. The results demonstrated that the highest average surface roughness values were obtained under dry conditions, with a value of 2.20 mu m while MQL (flank + rake directions) produces the lowest surface roughness value of 1.55 mu m with an improvement of 30%. Moreover, dual-jet MQL gives the lowest energy consumption (229 kJ) and tool wear (0.15 mm) with 23.67% and 52.38% enhancement, respectively.
查看更多>>摘要：Remaining useful life (RUL) prognostics is one of the most important parts in prognostics and health management, which can effectively avoid sudden accidents and economic losses caused by mechanical equipment failure. Previous artificial intelligence based prognostics method depends on manual feature extraction, which requires a lot of expert experience and prior knowledge for feature design. This paper presents a memory enhanced hybrid deep learning network (MEHDLN) combining convolution neural network and recurrent neural network, which contains convolution layer, pooling layer, bidirectional long short-term memory (BLSTM) layer and fully connected (FC) layer. It can not only extract local robust features from raw signals but also capture time-dependency in sequence sensor signals. The proposed MEHDLN model is verified by two experimental cases including rolling element bearing and turbine engine RUL prediction. Experimental results demonstrate the superiority of the MEHDLN over other state-of-the-arts.
查看更多>>摘要：The abnormal concentration of the metal ions in the environment threatens the health of Earth and human beings. At present, many methods have been employed to detect metal ions. Among this, the fluorescent sensor array based on pattern recognition has aroused tremendous attention. Unlike traditional "lock-key" type fluorescent probes, the sensor array can accomplish the detection of various metal ions simultaneously. Meanwhile, it has significant advantages such as excellent sensitivity, tunable emission range and high-throughput analysis. In this review, the fluorescent sensor arrays for metal ions detection over the last few years will be introduced. The analytical performances and the detection scopes of the arrays are discussed, as well as the approaches to realizing the high-accuracy discrimination and high-sensitivity detection.
查看更多>>摘要：A positioning system for complex construction scenarios is necessary to apply due to the limitations of the traditional positioning system in a non-line-of-sight (NLOS) environment, in order to study the impact of obstacles on construction sites. A quantitative measurement experiment of positioning precision in an NLOS environment was conducted in a petrochemical construction site, and a large number of engineering data were obtained, which showed the feasibility of a Passive Phased Array Radar - Bluetooth Hybrid Positioning System (PPAR-B HPS). The novelty of this paper is to propose a simplified signal coverage model for rapid measurement via the analysis of on-site data of the petrochemical industry and analyze the factors affecting the positioning precision in NLOS environment via a positioning precision heatmap analysis method to promoting the development and application of positioning technology in construction sites. The effectiveness of these methods are proved by empirical and comparative research.
查看更多>>摘要：A semi-analytical approach to the ill-posed inverse problem of reconstructing the dielectric constant of dielectric objects placed in free space or in a waveguide is proposed. It is shown that the advantage of an experiment, performed at huge frequency array, is the possibility of formulating a well-posed vector problem with attainable experimental parameters. The method substantiates the analysis of the operators of forward scattering problems, which makes it possible to justify the unique solvability of the studied inverse problem. It is proved that a solution to the problem can be found by the least squares method from the measurement data obtained in an imperfect experiment; it converges to the desired parameter of the test material while improving the quality of the experimental setup and reducing noise; the convergence rate grows with an increase in the number of frequencies used in the measurement.
查看更多>>摘要：Gearbox mainly including gears and bearings plays a significant role in adjusting the speed and torque in the rotating machinery, whose failure will seriously affect the production safety and industrial process. In this paper, a multi-signal fusion fault diagnosis method based on a reclassification model and an adaptive weighting mechanism is proposed. Different from the previous decision-making process of PNN, our reclassification model can make full use of the diagnosis information and prior knowledge, and a classification risk coefficient is introduced to derive a lower risk and more accurate results. The adaptive weighting mechanism designed for decision information fusion could assign more reasonable and flexible weights without depending on the experts. Finally, the proposed method is verified by a power transmission experimental platform. The results show that the proposed multi-signal fusion fault diagnosis method can effectively fuse multiple signals to achieve robust gearbox fault diagnosis and yields the promised results.
查看更多>>摘要：A high sensitivity optical fiber loop-based relative humidity (RH) sensor coated with polyvinyl alcohol (PVA) film is demonstrated, which has low-temperature sensitivity. The loop region of the sensor (micron-sized diameter) is very sensitive to the environmental medium due to strong evanescent fields out of fiber cladding. The refractive index (RI) sensitivity is as high as 2979 nm/RIU, while the temperature sensitivity is relatively low at 0.0075 nm/degrees C. The experimental results show that the sensor has the RH sensitivity of 0.533 nm/%RH (wavelength modulation) and -0.213 dBm/%RH (intensity modulation). The proposed sensor has good real-time, stability and repeatability, which provides a guarantee for accurate RH measurement.
查看更多>>摘要：Partial faults of bearings trigger periodic vibration features, but the interference makes fault diagnosis more difficult. A recursive sparse representation (RSR) algorithm is proposed to solve the fault diagnosis of bearings from sparse representation in the time and frequency domains. The tunable Q-factor wavelet transform (TQWT) filtering strategy is used to adaptively obtain the best wavelet with the signal vibration features. The optimal wavelet data is used as a fragment of each basic atom to obtain an optimal atomic complete dictionary (OACD) by Toeplitz's complementary zero expansion. The sparse representation based on the OACD obtains sparse coefficients with time domain features. The sparse group lasso (SGL) based on Majorize-Minimization (MM) optimization solves the sparse coefficients and extracts the primary vibration information in the frequency domain. Simulation experiments, signal experiments, and a comparative analysis of spectral kurtosis (SK) prove that RSR can effectively extract the vibration characteristics of faulty bearings.
NSTL
Elsevier