查看更多>>摘要：? 2022 Elsevier LtdThe multivariate statistic method has been widely applied, but no clear mapping relationship exists between the latent variables and the fault information, which leads to various information in different latent variables. The traditional methods cause the loss of useful fault information and the decline of monitoring performance. In this paper, a process monitoring method based on the optimal active relative entropy component is proposed. Based on global and local preserving projection, relative entropy is selected as the monitoring statistic. The influence of latent variable selection on relative entropy calculation is analyzed, and a relative entropy activity index is proposed to select the relative entropy component beneficial to process monitoring. The parameters are optimized to generate the optimal active relative entropy component for process monitoring using the mayfly algorithm. Finally, a numerical case, Tennessee Eastman (TE) process, and three-phase flow facility are used to verify the superiority of the monitoring algorithm.
查看更多>>摘要：? 2022The advancement of 3D scanning technology has gradually brought to light the issue of complex and time-consuming processing of high-density point cloud data. To address this need, this article proposes a method for point cloud simplification based on the concept of partitioning, which divides the point cloud's points into edge points, feature points, and non-feature points. On the basis of the normal angular difference, the edge points are extracted from the entire point cloud. The point cloud is then segmented by curvature into feature and non-feature regions using a region growing segmentation method. The feature points are determined by calculating the information entropy of the points in the feature region, whereas the non-feature points are extracted by voxel down-sampling the non-feature points. The experiment demonstrates that the proposed method effectively preserves the features and integrity of the point cloud while requiring less computational effort.
查看更多>>摘要：? 2022A mobile mapping system (MMS) is a widely-used platform to collect geospatial information. However, in the monotonous environment, current methods have inadequate performance in mapping accuracy because of lacking geometric features and constraints for point cloud alignment. We propose a systematic pedestrian dead reckoning (PDR) augmentation mapping framework for backpack MMS. The framework starts with data acquisition, followed by our proposed lightweight monotonous scene recognition method based on statistical features. An indicator is also proposed to measure monotonous degrees. Then, a step detection of PDR based on four-layer long short-term memory (LSTM) networks is implemented. Lastly, the PDR information is fused with the LiDAR odometry by a factor graph (FG). Experiments are conducted in two common monotonous environments, a tunnel and a long narrow alley. The results show that adding the PDR information can improve the mapping accuracy from meter-level to decimeter-lever or even centimeter-level in less serious monotonous conditions.
查看更多>>摘要：? 2022 Elsevier LtdThe purpose of this study is to investigate the existence of the optimal sound source driving signal toward a laboratory-designed acoustic-based volumeter for weights. The finite element (FE) simulation method is used for simulating the measuring system and predictively determining the qualities of the optimal sound source driving signal, including frequencies and amplitudes. Then, experimental studies are conducted to verify the predictions acquired by the FE simulation method. The volume measurement of 1–100 g weight is carried out, and the sound source driving signals that minimize the error of the weights’ volume measurements are treated as optimal. As the results, experimental measurements verify that the findings carry out by simulations. The uncertainty evaluation of the optimized acoustic volumetric measurement results is provided and shows that the extended uncertainties of the volumetric measurement of 50–100 g weights are less than 6 × 10?4. The relative expanded uncertainty of 1–20 g weights satisfy the requirement of the volumetric measurement expanded uncertainty for Class E1 weights according to OIML Recommendation R111.
查看更多>>摘要：? 2022 Elsevier LtdLocating individuals within a space has numerous potential uses within a smart environment. Many different technologies have been explored towards this end though privacy-concerns, the need to wear a device, and/or extensive building modifications have presented challenges towards adoption. Structural vibrations caused by footsteps have been shown to overcome these challenges though current methods rely on time-of-flight variations. This paper presents the use of the Force Estimation and Event Localization (FEEL) Algorithm that utilizes lower sampling rates, less sensors, etc than time-of-flight methods towards locating persons. Improvements to FEEL's force estimation and SDFE localization method are additionally presented with demonstrated increases in accuracy. Analysis of 1100 footsteps resulted in 98.6% localization accuracy using the improved FEEL. Ground force reactions (GRF) were estimated by FEEL and used to estimate participant body–weight-ratios (BWR). Estimated BWRs were within ranges reported in previous works for both barefoot and shoe cases.
查看更多>>摘要：? 2022 Elsevier LtdNew developments on Rogowski coil are presented due to the evolution of temporal shortening of the current pulses. Recently, to study biophysical stresses by electromagnetic pulses flat transmission lines are used. As a result, linear Rogowski coils for electrical current diagnostics have also been developed and applied. An electrostatic shield with a slim slit is used to protect the Rogowski coil. The presence of the slit is necessary to lead the input current around the coil. The response of the Rogowski coil on high frequency signals is influenced, not only by all inductances, the capacitance, the number of turns of the coil, the load resistance, but also by the small size of the slim slit operated on the metal shield. The new theory is able to justify the response of the device due to sub-ns pulses, ~100ps, on slit width. By the theory, the attenuation factor is dependent on the slit size. This behaviour was experimentally verified obtaining a value ranging from 15.6A/V to 24.7A/V. The longest measurable pulse was approximately 250ns. The device is very interesting owing to the radiation of the 5G communication mode.
查看更多>>摘要：? 2022 Elsevier LtdAccurate crack width measurement is crucial to determine the severity level of pavement cracks and the selection of crack repair strategy. We propose to combine the shortest method with the orthogonal projection method to produce a novel hybrid method. The hybrid method obtains the crack width by identifying a pair of points that give the shortest distance while being close to the orthogonal direction. We tested quantitatively and qualitatively the shortest, orthogonal projection and the hybrid methods on images taken from our CrackSkel700 dataset and two other open datasets, CrackForest, and Crack500. For the qualitative test, one hundred manual measurements are taken randomly from five images in the datasets to compare the shortest, orthogonal projection and hybrid methods on real cracks. Compared to the shortest and orthogonal projection methods, the hybrid method obtains the least root mean squared (RMS) error of 1.000 pixels and the least absolute pixel deviation of 0.732 pixels. Then, we generated 30 synthetic cracks using circles with a known diameter ranging from 3 pixels to 61 pixels to evaluate the accuracy of each method. The synthetic cracks generated a total of 18,404 ground truth measurements. Based on the synthetic cracks, the hybrid method obtains the least average absolute deviation of 1.769 pixels and the highest correlation coefficient of 0.956 compared to the shortest and orthogonal projection method on synthetic cracks. The qualitative comparisons of real and synthetic cracks show that the hybrid method improves the shortest method significantly by reducing the number of repeated measurements. On the other hand, the hybrid method improves the orthogonal projection method by reducing the overestimation of non-parallel and high curvature cracks. Hence, we show that the hybrid method generalizes better to more crack patterns and thus produces more accurate crack width estimation than the orthogonal projection and the shortest method.
查看更多>>摘要：? 2022 Elsevier LtdAs the premise of ensuring safe production and improving economic benefits, process monitoring and fault diagnosis technology plays a vital role in process industry. Traditional industrial process monitoring and fault diagnosis mostly focus on fault detection and identification, and seldom involve quantitative assessment of faults. Considering that different dimensionality reduction methods may affect the monitoring effect, this paper proposes a fault detection and quantitative assessment method based on global and local information features to reduce the influence of data preference for dimensionality reduction model. Firstly, kernel principal component analysis and sparse locally linear embedding are used to reduce the dimension of the data, and the features preserving global and local structural information are obtained respectively. Secondly, finding the projection matrices through canonical correlation analysis makes the correlation between global features and global featured maximum, and the features transformed by the projection matrices are fused. Fusion features not only retain the difference between single features, but also eliminate the redundant information. Then, support vector data description is utilized to monitor the fused data to complete fault detection and quantitative assessment. Finally, a fault detection and quantitative assessment experiment on Tennessee Eastman process is conducted to demonstrate the effectiveness of the proposed method.
查看更多>>摘要：? 2022 The AuthorsDistributed optical fiber sensors (DOFS) allow for distributed strain sensing and can be installed to function as extensometers for measuring point-displacements. This paper discusses the metrics of optimal sensing fiber selection for point-displacement measuring. Key metrics include the physical structure, mechanical parameters and light transmission coefficients. Calibration tests for verification of the optical fiber properties are designed and results of four fiber types are presented. Finally, creep and relaxation behavior of optical fibers is discussed based on manual tension test results, and a quantification model is proposed to assess the induced measurement error for sensing fiber. The maximum (absolute) measurement error for two common fiber types used in point displacement measurements is determined to be below 8%, and the study shows that pretensioning of the fiber helps to reduce such measurement errors.
查看更多>>摘要：? 2022 Elsevier LtdThe lack of data and poor quality of ground penetrating radar (GPR) images have limited the development of the object detection for internal cracks in asphalt pavement. To address this issue, this paper proposed a ‘DeepAugment’ data augmentation strategy combined with object detection models. First, the characteristic of internal cracks was determined with numerical simulation and GPR field test, which was in accordance with the coring results. Subsequently, the proposed DeepAugment method was used to enhance the crack features. Object detection results showed that the recognition accuracy and confidence level of internal crack detection improved by using the object detection model to test the enhanced GPR images, which was more noticeable in the YOLOv3 model. The proposed method is found to be of significance for accurately identifying internal cracks in GPR images, and the recognition accuracy after data enhancement can meet the needs of road maintenance engineering.
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