查看更多>>摘要：Gas monitoring sensor is prone to failure and its fault type is difficult to identify due to harsh working condition. In this work, a new sensor fault diagnosis method for gas leakage monitoring has been proposed derived from the Naive Bayes Classifier (NBC) and Probabilistic Neural Network (PNN). Firstly, NBC is used to identify the abnormal safety monitoring data. Then PNN is employed for sensor fault classification. The feasibility and effectiveness of this method are verified by applying it to the urban gas pipeline leakage monitoring system. It is shown that the abnormal monitoring data can be online distinguished, and sensor fault type can be effectively recognized. The global accuracy of abnormal data identification and the global accuracy of sensor fault diagnosis can reach 85% and 95%, respectively. This work can provide a guideline to improve the reliability of the urban gas pipeline monitoring systems.
查看更多>>摘要：This paper presents a method for sound speed measurement accounting for the infinite number of echoes of a continuous wave generated between an excitation and a receiving transducer. An infinite-echo model was developed for the output signal sensed by the receiving transducer. From the model, the amplitude of the output signal is shown to be a wave (the amplitude wave) with a periodicity dependent on sound speed, excitation frequency, and pathlength. This yields a method for sound speed measurement. The method was implemented and experimentally demonstrated. Effects of medium material, transducer property, excitation frequency, and pathlength were shown and analyzed for enhancing measurement robustness. Measurement of varied materials showed a high level of consistency with known values or expected variations. More importantly, outstanding signal-to-noise ratios were observed. The method can be used in different fields. Example applications were presented to illustrate the use and usefulness of the method.
查看更多>>摘要：In this paper, a compact multifunctional optical fiber sensor based on single mode fiber-photonic crystal fiber-no core fiber-photonic crystal fiber-single mode fiber-polarization maintaining fiber Bragg grating (SPNPS-PMFBG) has been proposed. By monitoring the wavelength and output power of the two resonance peaks of PMFBG, simultaneous measurement of salinity, temperature and strain can be realized. In our experiment under water, the sum output power of the two resonance peaks in 0-7 wt% salinity shows a good linear relationship and repeatability, and the sensitivity is -0.58 dB/wt% with 3 s response time. In addition, the measured temperature wavelength sensitivities at two resonance peaks are 0.042 nm/degrees C and 0.040 pm/degrees C, and the output power sensitivities are approximate to 0.079 dB/degrees C and 0.081 dB/degrees C, respectively. Further, the strain wavelength sensitivities are 0.535 nm/1000 mu epsilon, and the output power sensitivities are 0.65 dB/1000 mu epsilon and 0.70 dB/1000 mu epsilon.
查看更多>>摘要：With high power or high brightness laser as a heat source, metal additive manufacturing technology has developed rapidly in recent years. Although this technology is promising in manufacturing, quality detection has always been the main obstacle to its wide application. Traditional offline detection methods are expensive and time-consuming, and therefore cannot be used for online detection. An improved image processing algorithm is proposed to extract the number of powder spatters with a completely melted state from the images under a complex background, can retain the pixel features to the greatest extent, and exhibit high accuracy. To achieve automatic image annotation and predict the forming quality early in the process of additive manufacturing, the 3 Sigma quality evaluation standard on the basis of porosity is established which can solve the problem of single and broad quality evaluation threshold and categorize the quality into four levels. The inverse distance weights K-NearestNeighbor algorithm is then proposed to solve the problem of imbalance between positive and negative samples of different quality classes after quality classification. In general, the classification accuracy of this algorithm is above 95% in all data sets. Compared with other machine learning algorithms, this algorithm has strong interpretability, fewer parameters, faster operation speed, and greater flexibility in online detection. Online detection method proposed in this paper can mine the image information to reveal correlations between process parameters and quality features of interest, thereby monitoring process quality in real-time regardless of offline analysis.
查看更多>>摘要：Combining advantages of precise point positioning (PPP) and real-time kinematic (RTK), PPP-RTK has become a promising technology in the mass-market positioning. When performing PPP-RTK, atmospheric corrections enable the user fast ambiguity resolution as well as centimeter accuracy. However, the legacy method of obtaining atmospheric corrections, i.e., interpolating the atmospheric delay based on nearby reference stations, is not regular in space and needs the reference station coordinate information, thereby limiting real-time professional applications. In this contribution, a low-degree polynomial with regular grid residuals is investigated. Forming between-satellite single-differenced slant ionospheric delay, we theoretically analyze the reference network size. Afterwards, the zenith tropospheric delay and slant ionospheric delay accuracy using zero-, first and second-degree polynomials in calm atmospheric periods are about (5.6, 4.7 and 4.7) mm and (1.9, 1.3 and 1.3) cm. It is therefore recommended to adopt the first-degree polynomial model in terms of the accuracy and transmission load.
查看更多>>摘要：In the field of mechanical fault diagnosis, most of the collected signals are normal signals, leading to data imbalance and reduction of fault diagnosis performance. To address the issue, a conditional Wasserstein generative adversarial network with gradient penalty (CWGAN-GP) and the gated recurrent unit recurrent neural network (FDGRU) based method is proposed to improve the classification accuracy. Firstly, the CWGAN-GP is used to generate data. Specially, a Pearson correlation coefficient screening criterion (PCCSC) is proposed to ensure the quality of generated samples. Then, the generated data are added to the original data. Finally, FDGRU is applied for fault recognition. Extensive experiments are conducted, such as the influence of the number of health states, and the imbalance ratio, etc., to prove the effectiveness and stability of the proposed approach. Experimental results illustrate that the proposed approach can significantly enhance the classification accuracy of FDGRU in case of imbalanced data.
查看更多>>摘要：The aeration-oxidation method stated by the International Organisation of Vine and Wine (OIV) in the Resolution OIV-OENO 591A-2018 is internationally recognized as one of the election technique for free SO2 quantification in wine. The present work highlighted that an underestimation of the SO2 content is obtained by applying this 591A method. A measurement uncertainty evaluation on the basis of the Guide to the Expression of Uncertainty in Measurement and of the Monte Carlo simulations was carried out on a wine simulant solution with a known concentration of free SO2, prepared by gravimetry. By comparison between this 591A and the gravimetric methods, the obtained data resulted to be not consistent. To confirm this underestimation, measurement experiments were conducted by nine specialized laboratories with the 591A method on the same sample and none of which estimated the amount of free SO2 which was present in the wine simulant.
Shankar, M. GowriBabu, C. GaneshRajaguru, Harikumar
22页
查看更多>>摘要：This study emphasizes the classification of different cardiac diseases through bio-inspired classifiers with and without hyperparameters selection. Principal Component Analysis (PCA), Linearity Preserving Projection (LPP), Kernel-Linear Discriminant Analysis (K-LDA), and Variational Bayesian Matrix Factorization (VBMF) are used for the dimensionality reduction of ECG Signals. After the dimensionality reduction, the ECG features were classified using several classifiers such as Particle Swarm Optimization (PSO), Fish Swarm Optimization (FSO), Whale Optimization Algorithm (WOA), Grey Wolf Optimization (GWO), Support Vector Machine with (RBF (kernel)), K Nearest Neighbor (KNN) and Naive Bayesian Classifier (NBC). The average accuracy for the classifiers without hyperparameters selection is 64.99%. Further, the classifiers (PSO, FSO, WOA, and GWO) performance is enhanced through the selection of hyperparameters by the Adam and Randomized Adam (R-Adam) approaches. The average accuracy for the classifiers with Adam and R-Adam is at 72.32% and 85.63%. In this research, the MIT-BIH datasets of Atrial Fibrillation (AF), Premature Ventricular Contraction (PVC), ST Change (ST), Supra Ventricular Tachycardia (SVT), Ventricular Tachycardia (VT) and Normal Sinus Rhythm (NSR) are utilized from the physionet archived database. The Overall Accuracy (OA), Mean Square Error (MSE), F1-Score (F1), Fowlkes Mallows Index (FM), Mathew Correlation Coefficient (MCC) and Error Rate (ER) of the different classifiers with and without Adam and R-Adam methods are evaluated. The result demonstrates that the GWO-R-Adam classifier with the LPP dimensionality reduction technique with 98.90% overall accuracy in classifying {ST}-{NSR} classes outperforms all other classifiers in terms of classification performance measures.
Benhamou, Sidi MohamedLozano-Guerrero, Antonio JoseMadaoui, YemounaMonzo-Cabrera, Juan...
10页
查看更多>>摘要：A new inverse measuring technique that corrects non-desired sample displacements and can handle any kind of sample shapes is presented. It is applied to the estimation of permittivity and permeability of Poly-(3,4ethylenedioxythiophene)-maghnite (PEDOT-Mag) associated with different additives such as iron, copper, and hydrogen. This electromagnetic characterization has been performed over the 9 to 11 GHz frequency range by comparing the simulated and measured scattering parameters of a partially filled WR-90 waveguide. Additionally, the reflection, absorption multiple reflection losses and the shielding effectiveness of these materials have been calculated. Results show higher values of dielectric constant and loss factor for PEDOT-Mag-copper, than those compounds associated with hydrogen or iron. As expected, the highest permeability values are achieved by PEDOT-Mag-iron. The composite PEDOT-Mag-copper exhibits higher attenuation constant, absorption loss, multiple reflection loss and shielding efficiency values than composites associated with iron or hydrogen. PEDOT-Mag-hydrogen, however, shows the highest reflection loss values.
查看更多>>摘要：The accuracy of 3D shape measurement directly determines the quality and reliability of intelligent manufacturing, and point cloud registration is the key factor. However, the dislocation of discrete point clouds in the overlapping area seriously reduces the registration accuracy. This paper proposes a new high-accuracy registration method based on double constrained intersurface mutual projections. First, the initial registration set is built by mutual projections between similar local regions, then the final registration set is determined by the rigid transformation consistency constraint, finally, high-accuracy pairwise registration is realized. On this basis, the K-means clustering is further fused to achieve multiview global optimization. On Stanford dataset, both of the pairwise and multiview registration error significantly decreased. In the experiment with GoScanG1 scanner, the surface error of pairwise registration was reduced by 2.2%; that of the multiview registration was reduced by 42.5%, which shows the advancement of the new method in actual measurements.
NSTL
Elsevier