Recent advantages in the depth from defocus technique for the size and location determination of particles in dispersed two-phase flows have enabled the technique to detect and analyze spherical particle images in flo...
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Recent advantages in the depth from defocus technique for the size and location determination of particles in dispersed two-phase flows have enabled the technique to detect and analyze spherical particle images in flow systems with high number concentrations. In the present study, the use of convolutional neural networks for this task will be explored, with comparisons to the conventional analyses in terms of accuracy, tolerable concentration limits and computational speed. This approach requires a large teaching dataset of images, which is only practical and feasible if the dataset can be synthetically generated. Thus, the first development to be presented is an image generation procedure for out-of-focus neighboring spherical particles resulting in a known blurred image overlap. This image generation procedure is validated using laboratory images of known particle size distribution, position and image overlap, before creating a teaching dataset. The trained processing scheme is then applied to both synthetic datasets and to experimental data. The synthetic datasets allow limits of image overlap and tolerable volume concentration limits of the technique to be evaluated as a function of particle size distribution.(https://***/xu200911/Generate-overlapping-out-of-focus-particles)
The rapid development of convolutional neural networks (CNNs) has significantly contributed to the progress of intelligent fault diagnosis of mechanical transmission systems. Nevertheless, a significant number of prev...
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The rapid development of convolutional neural networks (CNNs) has significantly contributed to the progress of intelligent fault diagnosis of mechanical transmission systems. Nevertheless, a significant number of prevailing CNN-based diagnostic models may suffer from two notable constraints. First, the existing models often employ fixed temporal pooling for feature extraction, which restricts their ability to effectively capture and analyze a comprehensive range of temporal information. Second, these models may struggle to precisely forecast the operational state of the monitored machinery amidst nonstationary circumstances, such as time-varying or disturbed environments. These challenges limit their feature extraction capabilities and hinder their practical implementation and utilization. To tackle the aforementioned issues, this study develops a multiperspective temporal pooling CNN (MTPCNN). The main contributions encompass: 1) a multikernel feature perception module (MFPM) and a balanced attention module (BAM) are established for multilevel information exploration and optimal feature selection and 2) an innovative multiperspective temporal pooling learning (MTPL) strategy is introduced to aid the model in dynamically selecting the optimal temporal pooling method for the input data. A laboratory dataset collected from a gearbox fault simulator and an industrial dataset collected from a high-speed rail are used for the validation of the proposed approach. The extensive experimental results validate the superiority of the developed MTPCNN model over seven competitive approaches.
High demand for computation and storage largely hinders the deployment of deep convolutional neural networks (CNNs) in resource constrained devices. Regularization-based pruning methods are effective for the model com...
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High demand for computation and storage largely hinders the deployment of deep convolutional neural networks (CNNs) in resource constrained devices. Regularization-based pruning methods are effective for the model compression of CNNs by introducing a regularization term into the loss function. However, such methods typically compress weights to zero utilising a fixed regularization factor, which cannot impose different punishments on weights or structures with different importance. In this paper, a group regularization method is proposed to impose a dynamic regularization factor to each filter of convolutional layers, named GRDRF. The scaling factors of batch normalization (BN) layer are used to represent the importance of filters and construct updatable and dynamic regularization factors according to the importance representation. Moreover, a novel pruning strategy of ResNet is proposed, which can significantly improve the pruning performance. Numerical experiments on the popular CNN architectures and CIFAR-10 dataset are performed to verify the efficiency of the new group regularization method and the ResNet pruning strategy. The programs are publicly provided on https://***/xiaoli7766111/DRF.
Ensuring the safe, reliable, and cost-efficient operation of transportation systems such as elevators is critical for the maintenance of civil infrastructures. The ability to monitor the health state and classify diff...
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Ensuring the safe, reliable, and cost-efficient operation of transportation systems such as elevators is critical for the maintenance of civil infrastructures. The ability to monitor the health state and classify different operational states (elevator moving up/down, stopped, doors opening/closing) may lead to the development of intelligent solutions, such as diagnostics and predictive maintenance. Accordingly, downtime and maintenance costs can be significantly reduced with an accurate monitoring of the operation parameters and dynamics. In this context, this paper presents a novel approach for the operational state classification of elevator systems based on a one-dimensional convolutionalneural network, using exclusively a single axis (Z) of an accelerometer signal. The proposed model utilizes a single accelerometer and addresses the challenge of distinguishing overlapping signal patterns, such as those produced by vertical displacement and door movements. The approach includes an interpretability stage, which demonstrates the data processing involved in extracting features from the underlying physical phenomena captured in the acceleration signal. Obtained results have been validated with an on-site captured dataset which contains 250 elevator journeys and compared with three other classification methods that have been conventionally used: generalized likelihood ratio test (GLRT), barometer-assisted GLRT, and three conventional machine learning modelss. It has been shown that the proposed approach is very accurate, with 96% of the average F1 score and, importantly, includes the analytic relation of the classification model features.
This paper proposes a probabilistic framework for generating three-dimensional (3D) synthetic ground motions using deep learning techniques-specifically, generative adversarial networks (GAN) and convolutionalneural ...
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This paper proposes a probabilistic framework for generating three-dimensional (3D) synthetic ground motions using deep learning techniques-specifically, generative adversarial networks (GAN) and convolutional neural networks (CNN). Deep learning methods have been shown to surpass classical model classes in performance when provided with large datasets, and the ever-increasing number of ground motion records provides an opportunity to design generative models to produce artificial ground motions that outperform classical models. In addition, these methods can directly extract features and patterns from ground motion data without loss of generality, enabling prediction and generation of synthetic ground motions. The proposed framework consists of two distinct deep learning modules. The first generates normalized 3D synthetic ground motions given source and site characteristics. For this purpose, a conditional Wasserstein GAN comprising a generator and a critic in an adversarial setup is designed in which they engage in a simultaneous competitive process. Through learning from the dataset of real ground motions, the generator attempts to generate artificial ground motions that are more convincing to the critic, whereas the critic seeks to improve its ability to identify the realness or artificialness of the motions and provide the generator with feedback. The second module produces peak ground accelerations (PGA) for the three spatial components of the generated normalized ground motion, given the normalized motion and the said characteristics. For this purpose, a CNN is designed with "inception" layers, each of which concurrently applies multiple convolution filters of varying sizes to the input and concatenates their outputs, enabling the network to efficiently capture features at various scales. The learning performance of both modules is improved by realistic data augmentation techniques that increase training data size and are specifically designed for 3D ground
The MagNet challenge 2023 called upon competitors to develop data-driven models for the material-specific, waveform-agnostic estimation of steady-state power losses in toroidal ferrite cores. The following HARDCORE (H...
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The MagNet challenge 2023 called upon competitors to develop data-driven models for the material-specific, waveform-agnostic estimation of steady-state power losses in toroidal ferrite cores. The following HARDCORE (H-field and power loss estimation for arbitrary waveforms with residual, dilated convolutional neural networks in ferrite cores) approach shows that a residual convolutionalneural network with physics-informed extensions can serve this task efficiently when trained on observational data beforehand. One key element is an intermediate model layer, which first reconstructs the $BH$ curve, and then, estimates the power losses based on the curve's area rendering the proposed topology physically interpretable. In addition, emphasis was placed on expert-based feature engineering and information-rich inputs in order to enable a lean model architecture. A model is trained from scratch for each material, while the topology remains the same. A Pareto-style tradeoff between model size and estimation accuracy is demonstrated, which yields an optimum at as low as 906 parameters and down to below 8% for the average 95th percentile of the relative power loss error across diverse materials. This contribution has won the first place in the performance category of the MagNet challenge 2023, which further highlights the effectiveness of the proposed model.
Deep neural network-based direction of arrival (DOA) estimation systems often rely on spatial features as input to learn a mapping for estimating the DOA of multiple talkers. Aiming to improve the accuracy of multi-ta...
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Deep neural network-based direction of arrival (DOA) estimation systems often rely on spatial features as input to learn a mapping for estimating the DOA of multiple talkers. Aiming to improve the accuracy of multi-talker DOA estimation for binaural hearing aids with a known number of active talkers, we investigate the usage of periodicity features as a footprint of speech signals in combination with spatial features as input to a convolutionalneural network (CNN). In particular, we propose a multi-talker DOA estimation system employing a two-stage CNN architecture that utilizes cross-power spectrum (CPS) phase as spatial features and an auditory-inspired periodicity feature called periodicity degree (PD) as spectral features. The two-stage CNN incorporates a PD feature reduction stage prior to the joint processing of PD and CPS phase features. We investigate different design choices for the CNN architecture, including varying temporal reduction strategies and spectro-temporal filtering approaches. The performance of the proposed system is evaluated in static source scenarios with 2-3 talkers in two reverberant environments under varying signal-to-noise ratios using recorded background noises. To evaluate the benefit of combining PD features with CPS phase features, we consider baseline systems that utilize either only CPS phase features or combine CPS phase and magnitude spectrogram features. Results show that combining PD and CPS phase features in the proposed system consistently improves DOA estimation accuracy across all conditions, outperforming the two baseline systems. Additionally, the PD feature reduction stage in the proposed system improves DOA estimation accuracy while significantly reducing computational complexity compared to a baseline system without this stage, demonstrating its effectiveness for multi-talker DOA estimation.
Currently, convolutional neural networks (CNNs) have demonstrated extensive success in numerous practical applications. Nevertheless, their limited interpretability remains a significant barrier to further advancement...
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Currently, convolutional neural networks (CNNs) have demonstrated extensive success in numerous practical applications. Nevertheless, their limited interpretability remains a significant barrier to further advancement in certain crucial fields. Improving the interpretability of CNNs stands as an exceptionally compelling topic in the present time. This paper explores the interpretability of a basic CNN incorporating a convolution-pooled block and a fully connected layer from a statistical perspective. Assuming that the input variables adhere to a normal distribution and maintain independence from each other, the output variables subsequent to the convolution and pooling layers also conform to a normal distribution. Simultaneously, the probability density function (pdf) characterizing the final output variable belongs to an exponential family distribution. By introducing intermediate variables, the pdf of this output variable can be expressed as a linear combination of three distinct normal distributions. Furthermore, the likelihood of the predicted class label can be rewritten as a cumulative density function (cdf) of the standard normal distribution. The originality of this paper lies in its provision of a more innovative and intuitive perspective for dissecting the operational mechanism of CNNs, analyzing them layer by layer to improve their interpretability. Experimental results obtained from both an artificial dataset and the image datasets CIFAR-10 and ImageNet further validate the rationality of these conclusions.
convolutional neural networks (CNNs) have been widely applied in chemical process fault diagnosis due to their superior feature extraction capabilities. However, the inherent complexity and variability of chemical env...
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convolutional neural networks (CNNs) have been widely applied in chemical process fault diagnosis due to their superior feature extraction capabilities. However, the inherent complexity and variability of chemical environments, involving multivariable interactions, noise interference, and other factors, pose challenges that hinder the direct application of CNNs. These limitations may compromise the accuracy of fault diagnosis by hindering the full exploitation of CNNs' feature extraction capabilities. To address these challenges, this paper proposes a novel fault diagnosis method for chemical processes based on a variable correlation-guided CNN. The proposed method uses the Pearson correlation coefficient to identify strongly correlated variable groups, integrating them into the original variables. This integration facilitates the convolution of these strongly correlated variables, thereby enhancing the extraction of more discriminative features and optimizing fault diagnosis methods. This approach enables CNNs to more accurately extract fault-relevant features, thereby improving diagnostic performance. The effectiveness of the proposed method is validated through comprehensive numerical simulations and the Tennessee Eastman (TE) process dataset. The results demonstrate substantial enhancements in both the accuracy and reliability of fault detection, validating the superiority of the proposed method.
Identifying sedimentary lithofacies, including their characteristics and distribution, is a common method to describe geological heterogeneity. Characterizing microlithofacies within shale fabric requires the integrat...
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Identifying sedimentary lithofacies, including their characteristics and distribution, is a common method to describe geological heterogeneity. Characterizing microlithofacies within shale fabric requires the integration of multi-scale, multimodal data. In this study, we identify 6 representative microlithofacies within a Vaca Muerta shale sample using convolutional neural networks. We characterize the two main porous microfacies using Focused Ion Beam-Scanning Electron Microscopy (FIB-SEM) and Scanning Transmission Electron Microscopy (STEM) imaging to understand the characteristics and roles of connected pores. The coccolithic mud microfacies, rich in carbonates, contains well-connected organic pores, intraparticle pores within clays, as well as interparticle pores in between grains. The organic-rich clayey mud microfacies has a large and well connected organic pore network. In both microfacies, the larger pores playa key role in connecting the abundant organic nanopores to meso- and macro-scale flow paths. Importantly, 2D information in FIB-SEM is insufficient to characterize fully the nanopores, and 3D STEM tomography is needed to probe connectivity. Given the impact of nanoscale processes on hydrocarbon production, high-resolution imaging techniques are necessary to characterize fully the formation. In particular, we show that most of the porosity exists below 100 nm for both microfacies, and abundant organic nanopores can be as small as a few nanometers.
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