Suppress Noise Interference Research Articles

Adaptive scale chirplet transform and its application to bearing fault analysis

In response to the problems of biased estimation of instantaneous frequency (If) and poor noise immunity in current time–frequency (Tf) analysis methods, the adaptive scale chirplet transform (ASCT) is proposed in this paper. The core idea of the proposed algorithm is to use a frequency-dependent quadratic polynomial kernel function to approximate the IF of the signal and to use the time-varying window length to overcome the frequency resolution problem due to the change in signal modulation. This method can dynamically select suitable parameters and overcome the disadvantage of unfocused energy of TF distribution. The experimental results show that the ASCT algorithm has high TF aggregation and can suppress noise interference well. In practical signal processing, the advantage of the ASCT algorithm is that it can accurately depict the characteristic frequency of the signal and detect the fault in the bearing signal. Both simulation and experimental results prove the strong realistic relevance of this algorithm.

Study of High Frequency Characteristics Modeling and EMI Suppression of Common Mode Chokes

This paper proposes a method for building a high-frequency model of common-mode chokes in the frequency range of 9kHz to 200MHz. The method only needs to measure the common mode and differential mode impedance data of the common mode choke, and then use the differential evolution algorithm to process the impedance data to complete its high-frequency modeling. Comparison with the high-frequency model obtained by using a genetic algorithm shows that the method has high accuracy. After the high frequency modeling of the common mode chokes, the high frequency modeling of the X and Y capacitors is performed using the differential evolution algorithm, and the high frequency model of the EMI filter is obtained by combining it with the established high frequency model of common mode chokes. By comparing the measured and simulated conducted interference noise suppression effect of the EMI filter, the high frequency model of the common mode chokes is verified to suppress the conducted interference, and the effectiveness of the common mode choke high frequency modeling method is determined.

Nonlinear vibration feature extraction based on power spectrum envelope adaptive empirical Fourier decomposition

Analyzing the vibration features of a shipboard stabilized platform (SSP) is significant to the design or vibration compensation of a marine gravimetric survey vibration isolation system. Empirical Fourier decomposition (EFD) is a recently developed method for nonlinear and non-stationary signal decomposition. However, the spectral segmentation boundary needs to be set in advance according to sophisticated experience, and it is easy to be disturbed by noise, and the decomposition result is inaccurate. In order to accurately extract the nonlinear vibration characteristics of SSP, this paper proposes a new method called power spectrum envelope adaptive empirical Fourier decomposition (PSEEFD). Firstly, the number of selected modal decomposition is determined based on the mutual information to realize adaptive segmentation. Then, the improved power spectrum envelope segmentation method is adopted to effectively diminish the interference of noise since the segmentation boundary is formed by the minimum of the adjacent extreme points enveloped by the maximum value of the power spectrum. The spectrum segments obtained from segmentation contain less interference. Finally, the component signal in each frequency band is reconstructed by inverse fast Fourier transform, and the instantaneous frequency signal component with physical significance is obtained. Through the analysis of vibration simulation signals and measured data of SSP, the proposed method is compared with EMD, AFVMD, EWT and EFD. The results show that PSEEFD has a well suppression of noise interference and can effectively extract the characteristics of nonlinear vibration signals.

RLS Channel Estimation Combined with Channel Equalization in Oversampled Frequency Domain for FBMC-QAM Systems

In order to reduce the bit error rate and improve the anti-interference performance, this paper proposes a channel estimation algorithm based on RLS. RLS channel estimation algorithm obtains the current estimation data by modifying the final estimation data. First, the first data is estimated by least squares (LS), and then the date is adjusted in real time through forgetting factor and recursive formula to obtain all estimated data. The results show that RLS channel estimation algorithm can reduce the computation, improve the accuracy of channel estimation, and suppress noise interference. As the number of iterations increases, the channel estimation will be more accurate, effectively reducing the bit error rate.

An Anti-Noise Fast Circle Detection Method Using Five-Quadrant Segmentation

Extracting circle information from images has always been a basic problem in computer vision. Common circle detection algorithms have some defects, such as poor noise resistance and slow computation speed. In this paper, we propose an anti-noise fast circle detection algorithm. In order to improve the anti-noise of the algorithm, we first perform curve thinning and connection on the image after edge extraction, then suppress noise interference by the irregularity of noise edges and extract circular arcs by directional filtering. In order to reduce the invalid fitting and speed up the running speed, we propose a circle fitting algorithm with five quadrants, and improve the efficiency of the algorithm by the idea of "divide and conquer". We compare the algorithm with RCD, CACD, WANG and AS on two open datasets. The results show that we have the best performance under noise while keeping the speed of the algorithm.

Weakly-Supervised Semantic Feature Refinement Network for MMW Concealed Object Detection

The concealed object detection in millimeter-wave human body images is a challenging task due to the noise and dim-small objects. Exploiting the spatial dependencies to mine the difference between the object and the noise is vital for the discrimination of objects. However, most approaches ignore the context around the object. In this paper, a concealed object detection framework based on structural context is proposed to suppress noise interference and refine localizable semantic features. The framework consists of two subnetworks, structural region-based multi-scale weakly supervised feature refinement and local context-based concealed object detection. The multi-scale weakly supervised feature refinement is constructed to learn position-aware semantics of objects of various sizes while suppressing background noises in structural regions. Specifically, a multi-scale pooling method is proposed to better localize objects of different sizes, and an object-activated region enhancement module is designed to strengthen object semantic representations and suppress the background interference. Moreover, an adaptive local context aggregation module is designed to integrate the local context around the bounding box in the concealed object detection, which improves the discrimination of the model for the dim-small objects. Experimental results on the AMMW and the PMMW datasets demonstrate that the proposed approach improves detection performance with lower false alarm rates.

Non-Cooperative Target Attitude Estimation Method Based on Deep Learning of Ground and Space Access Scene Radar Images

Determining the attitude of a non-cooperative target in space is an important frontier issue in the aerospace field, and has important application value in the fields of malfunctioning satellite state assessment and non-cooperative target detection in space. This paper proposes a non-cooperative target attitude estimation method based on the deep learning of ground and space access (GSA) scene radar images to solve this problem. In GSA scenes, the observed target satellite can be imaged not only by inverse synthetic-aperture radar (ISAR), but also by space-based optical satellites, with space-based optical images providing more accurate attitude estimates for the target. The spatial orientation of the intersection of the orbital planes of the target and observation satellites can be changed by fine tuning the orbit of the observation satellite. The intersection of the orbital planes is controlled to ensure that it is collinear with the position vector of the target satellite when it is accessible to the radar. Thus, a series of GSA scenes are generated. In these GSA scenes, the high-precision attitude values of the target satellite can be estimated from the space-based optical images obtained by the observation satellite. Thus, the corresponding relationship between a series of ISAR images and the attitude estimation of the target at this moment can be obtained. Because the target attitude can be accurately estimated from the GSA scenes obtained by a space-based optical telescope, these attitude estimation values can be used as training datasets of ISAR images, and deep learning training can be performed on ISAR images of GSA scenes. This paper proposes an instantaneous attitude estimation method based on a deep network, which can achieve robust attitude estimation under different signal-to-noise ratio conditions. First, ISAR observation and imaging models were created, and the theoretical projection relationship from the three-dimensional point cloud to the ISAR imaging plane was constructed based on the radar line of sight. Under the premise that the ISAR imaging plane was fixed, the ISAR imaging results, theoretical projection map, and target attitude were in a one-to-one correspondence, which meant that the mapping relationship could be learned using a deep network. Specifically, in order to suppress noise interference, a UNet++ network with strong feature extraction ability was used to learn the mapping relationship between the ISAR imaging results and the theoretical projection map to achieve ISAR image enhancement. The shifted window (swin) transformer was then used to learn the mapping relationship between the enhanced ISAR images and target attitude to achieve instantaneous attitude estimation. Finally, the effectiveness of the proposed method was verified using electromagnetic simulation data, and it was found that the average attitude estimation error of the proposed method was less than 1°.

Surface detection method of glass fibre composites based on computer vision

Considering the high cost, low efficiency and poor real-time performance of manual inspection methods in detecting surface defects such as glass fibre imprints, resin build-up and wrinkles, in this paper, a machine vision-based method is proposed to detect surface defects of glass fibre composites. The method designs an automatic inspection platform using two high-resolution line scan cameras for image acquisition. The eight directional templates of the Kirsch operator are used to convolve the derivatives of the image pixel points respectively, and the largest template is selected to determine its edge direction, and the detection of surface defects is achieved by combining with the Canny operator. The experimental results show that the proposed algorithm can well suppress noise interference, improve the accuracy of edge localisation and detection, and well retain edge information while avoiding pseudo-edges.

A novel adaptive noise reduction method for field natural gas pipeline defect detection signals

To suppress noise interference and improve defect identification accuracy, we propose a transfer learning-based adaptive wavelet neural network (AWNN) method for pipeline defect detection signal denoising. Simulated noisy signals and field detection signals are used to determine the network's initial structure and fine-tune its parameters. The Meyer wavelet basis function is chosen as an excitation function based on the defect signal waveform. The pretrained structure is determined by a search algorithm. The network parameters are adaptively fine-tuned according to the sample entropy of the noise. The new genetic beetle antennae search strategy (GBA) optimization algorithm is proposed to improve the AWNN to avoid local optima. Compared with traditional noise reduction methods, the AWNN has excellent ability to recovery the pure denoised signal with a higher SNR and smaller RMSE. The AWNN can realize adaptive noise reduction of different field signals, providing reliable input for subsequent defect diagnosis.

Forward looking sonar image segmentation based on empirical mode decomposition

Due to the low imaging quality and serious noise pollution of forward-looking sonar images, traditional image segmentation methods based on edge information or statistical information are difficult to obtain high precision and robust segmentation results. Therefore, it is very complicated to segment forward-looking sonar images. Based on the analysis of the characteristics of forward-looking sonar, a new image segmentation method for forward-looking sonar is proposed.Firstly, 2d maximum entropy segmentation principle combined with chicken flock optimization algorithm is used to remove the background of the forward-looking sonar image.Then, based on 2d empirical mode decomposition, appropriate eigenmode functions are selected to denoise and enhance the forward-looking sonar image.Finally, the reconstructed forward-looking sonar image is segmented by enhanced fuzzy C-means clustering, and the segmented forward-looking sonar image result is obtained. This method can not only suppress noise interference effectively, but also protect the details of image edge for segmentation.

Real-time iris segmentation model based on lightweight convolutional neural network

Iris segmentation is an important task in the iris recognition system. Traditional iris segmentation methods are susceptible to irrelevant noise. At present, segmentation methods based on convolutional neural networks (CNNs) have become the main trend in addressing the task. Although these networks achieve promising segmentation performance on the advanced graphics processor, they require a lot of computation and time, which are far from meeting the standards of real-time iris segmentation. To this end, a precise and fast iris segmentation algorithm is proposed. First, an efficient feature extraction network that combines depth-wise separable convolution with dilated convolution is designed to reduce model parameters while maintaining segmentation accuracy. Then, an attention mechanism is introduced to suppress noise interference and enhance the discriminability of the iris region. Finally, an auxiliary training branch is proposed to overcome the vanishing gradient problem. Experimental results show that the proposed method not only achieves state-of-the-art performance but also is more efficient in terms of required parameters, calculated load, and storage space. Specifically, the model parameter is only 0.1 million (M), and the average prediction time is <0.03 seconds (S).

Weak Signal Detection Based on Combination of Sparse Representation and Singular Value Decomposition

Due to the inevitable acquisition system noise and strong background noise, it is often difficult to detect the features of weak signals. To solve this problem, sparse representation can effectively extract useful information according to the sparse characteristics of signals. However, sparse representation is less effective against non-Gaussian white noise. Therefore, a novel SRSVD method combining sparse representation and singular value decomposition is proposed to further improve the denoising performance of the algorithm. All the signal components highly matched with the dictionary are extracted by sparse representation, and then each component of singular value decomposition is weighted by the evaluation index, PMI, which can indicate the component with useful information in the signal, so that the signal denoising performance of the algorithm is greatly improved. The performance of the proposed method is verified by the processing of weak signals in the circuit and early fault signals of bearings. The results show that SRSVD can successfully suppress noise interference. Compared with other existing methods, SRSVD has better denoising performance.

Combined Spatial-Spectral Hyperspectral Image Classification Based on Adaptive Guided Filtering

Hyperspectral image classification has a low accuracy in the face of a small training set. To solve the problem, this paper proposes a combined spatial-spectral hyperspectral image classification approach based on adaptive guided filtering. From coarse to fine classification, the local binary pattern (LBP) histogram features were improved, the spatial contrast description was enhanced, and enhanced spatial-spectral features were prepared through Gabor transform of different scales and directions, combined with super pixel blocks. Then, the pre-classification was completed by the support vector machine (SVM) classifier. To reduce noise interference, the pre-classification results were filtered again by a guided filter based on the adaptive regularization factor. To verify its effectiveness, the proposed approach was compared with the state-of-the-arts approaches through repeated experiments. The comparison shows that our approach achieved a high classification accuracy, while suppressing noise interference. This research provides a new tool for hyperspectral image classification with a small training set.

SVM Classification Method of Waxy Corn Seeds with Different Vitality Levels Based on Hyperspectral Imaging

The vitality of corn seeds is a significant indicator for assessing the quality and yield of crops. In recent years, numerous information technologies have been adopted to analyze the seed vitality and provide support for efficient equipment. However, there are still some shortcomings in these technologies, which decrease the accuracy of identifying the seed vitality for various practical applications. In this paper, a synthesized classification method for seed vitality was proposed based on multisensor hyperspectral imaging. Firstly, hyperspectral images in the range of 370-1042 nm were collected for waxy corn seeds, which were subjected to aging processing with four periods of time (0, 3, 6, and 9 d). Besides, some preprocessing techniques including standard normal variate, multiplicative scatter correction, Savitzky-Golay smoothing, and first-order and second-order derivatives were employed to suppress noise interference in raw spectra. In addition, principal component analysis (PCA), 2nd derivatization, and successive projection algorithm (SPA) were adopted to select feature wavelengths. Moreover, SVM classification models based on full spectra and feature wavelengths were established. The results showed that, based on feature wavelengths selected by SPA, the SVM model preprocessed by multiplicative scatter correction (MSC) had the optimal performance. The training accuracy and testing accuracy of this model were 100% and 97.9167%, respectively. RMSE was 0.018 and R 2 was 0.875. Therefore, it can be demonstrated that the pattern recognition algorithm could achieve a high accuracy in classifying accelerated aging seeds. This algorithm provides a new method for machine learning (ML) in nondestructive detection of crops.

Object-Level Visual-Text Correlation Graph Hashing for Unsupervised Cross-Modal Retrieval.

The core of cross-modal hashing methods is to map high dimensional features into binary hash codes, which can then efficiently utilize the Hamming distance metric to enhance retrieval efficiency. Recent development emphasizes the advantages of the unsupervised cross-modal hashing technique, since it only relies on relevant information of the paired data, making it more applicable to real-world applications. However, two problems, that is intro-modality correlation and inter-modality correlation, still have not been fully considered. Intra-modality correlation describes the complex overall concept of a single modality and provides semantic relevance for retrieval tasks, while inter-modality correction refers to the relationship between different modalities. From our observation and hypothesis, the dependency relationship within the modality and between different modalities can be constructed at the object level, which can further improve cross-modal hashing retrieval accuracy. To this end, we propose a Visual-textful Correlation Graph Hashing (OVCGH) approach to mine the fine-grained object-level similarity in cross-modal data while suppressing noise interference. Specifically, a novel intra-modality correlation graph is designed to learn graph-level representations of different modalities, obtaining the dependency relationship of the image region to image region and the tag to tag in an unsupervised manner. Then, we design a visual-text dependency building module that can capture correlation semantic information between different modalities by modeling the dependency relationship between image object region and text tag. Extensive experiments on two widely used datasets verify the effectiveness of our proposed approach.

Aided Recognition and Training of Music Features Based on the Internet of Things and Artificial Intelligence.

With the development of the Internet of Things, many industries have been on the train of the information age, and digital audio technology is also constantly developing. Music retrieval has gradually become a research hotspot in the music industry. Among them, the auxiliary recognition of music characteristics is also a particularly important Task. Music retrieval is mainly to manually extract music signals, but now the music signal extraction technology has encountered a bottleneck. The article uses Internet and artificial intelligence technology to design an SNN music feature recognition model to identify and classify music features. The research results of the article show (1) statistic graphs of the main melody and accompanying melody of different music. The absolute value of the main melody and accompanying melody mainly fluctuates in the range of 0–7, and the proportion of the main melody can reach 36%. The accompanying melody can reach 17%. After the absolute value of the interval reaches 13, the interval ratio of the main melody and the accompanying melody tends to be stable, maintaining between 0.6 and 0.9, and the melody interval ratio value completely coincides; the main melody in the interval variable is X. (1) The relative difference value in the interval of −X(16) fluctuates greatly. After the absolute value of the interval reaches 17, the interval ratio of the main melody and the accompanying melody tends to be stable, maintaining between 0.01 and 0.04 and the main melody. The value of the difference is always higher than the accompanying melody. (2) When the number of feature maps is 24∗5, the recognition result is the most accurate, MAP recognition result can reach 78.8, and the recognition result of precision@ is 79.2; when the feature map size is 5∗5, the recognition result is the most accurate, MAP recognition result can reach 78.9, the recognition result of precision@ is 79.2, and the recognition result of HAM2 (%) is 78.6. The detection accuracy of the SNN music recognition model proposed in the article is the highest. When the number of bits is 64, the detection accuracy of the SNN detection model is 59.2%, and the detection accuracy of the improved SNN music recognition model is 79.3%, which is better than the detection rate of ITQ music recognition model of 17.9%, which is 61.4% higher. The experimental data further shows that the detection efficiency of the ITQ music recognition model is the highest. (3) The SNN music recognition model proposed in the article has the highest detection accuracy, regardless of whether it is in a noisy or no-noise music environment, with an accuracy rate of 97.97% and a detection accuracy value of 0.88, which is 5 types of music. The highest one among the recognition models, the ITQ music recognition model, has the lowest detection accuracy, with a detection accuracy of 67.47% in the absence of noise and a detection accuracy of 70.23% in the presence of noise. Although there is a certain noise removal technology, it can suppress noise interference to a certain extent, but cannot accurately describe music information, and the detection accuracy rate is also low.

High sensitivity fault location technology for distribution networks considering measurement error

Accurately identifying weak fault characteristics is a critical issue for locating high impedance faults (HIFs) in distribution networks. Due to the measurement error of current sensors, the weak fault signals are easily submerged by the measurement noise interference. Nonetheless, the impact of measurement error is rarely considered explicitly. The present work addresses this issue by proposing a weak fault characteristics extraction algorithm based on an adaptive Fourier decomposition method (FDM) that can effectively suppress noise interference, and accurately locate faults with high sensitivity. First, the generalized Fourier expansion method is applied to obtain a series of independent and uncorrelated Fourier intrinsic band functions (FIBFs) adaptively by decomposing the noisy zero sequence current (ZSC) signal sampled from current sensors. Then, the FIBFs are employed to construct a set of Fourier-Hilbert spectra, which are utilized to map the noisy ZSC into a series of frequency distributions that includes the weak fault characteristic information of the HIF. The proposed density-distance search scheme can quickly identify the frequency center of gravity on both sides of the fault point to achieve reliable convergence of the clustering algorithm. Numerical simulations and field testing demonstrate that the proposed method can accurately locate HIFs with high sensitivity. Moreover, the observability and reliability of the distribution networks are improved.

Design of Athlete’s Running Information Capture System in Space-Time Domain Based on Virtual Reality

In order to improve the training effect of athletes, aiming at the problems of inaccurate information capture results, poor real-time performance of sports information capture, and inability to effectively suppress noise interference in traditional methods, an athlete space-time running information capture system based on virtual reality is designed. Establish the athlete’s human skeleton, obtain the athlete’s sports joint points, design the overall architecture of the athlete’s space-time running information capture system, and realize the whole link design of sports information capture through RF chip, infrared camera, sports data acquisition module, data transmission module, and human-computer interaction module. Based on virtual reality technology, a virtual reality environment is built to obtain the characteristic parameters of athletes’ sports posture in space-time domain, and the median filtering algorithm is used to filter the original signal to eliminate the impact of noise signal on athletes’ sports information capture. Finally, the activity of the motion region is detected, and the motion information is captured combined with the Gaussian mixture model. The experimental results show that the system designed in this paper has high accuracy and anti-interference and can realize the real-time capture of motion information.

Adaptive Cross-Attention-Driven Spatial–Spectral Graph Convolutional Network for Hyperspectral Image Classification

Recently, graph convolutional networks (GCNs) have been developed to explore the spatial relationship between pixels, achieving better classification performance of hyperspectral images (HSIs). However, these methods fail to sufficiently leverage the relationship between spectral bands in HSI data. As such, we propose an adaptive cross-attention-driven spatial–spectral graph convolutional network (ACSS-GCN), which is composed of a spatial GCN (Sa-GCN) subnetwork, a spectral GCN (Se-GCN) subnetwork, and a graph cross-attention fusion module (GCAFM). Specifically, Sa-GCN and Se-GCN are proposed to extract the spatial and spectral features by modeling the correlations between spatial pixels and between spectral bands, respectively. Then, by integrating attention mechanism into information aggregation of the graph, the GCAFM, including three parts, i.e., the spatial graph attention block, the spectral graph attention block, and the fusion block, is designed to fuse the spatial and spectral features, and suppress noise interference in Sa-GCN and Se-GCN. Moreover, the idea of the adaptive graph is introduced to explore an optimal graph through backpropagation during the training process. Experiments on two HSI datasets show that the proposed method achieves better performance than other classification methods.

The Acoustic Imaging of the Broadband Dipole Sound Sources of Helicopter Rotor in the Wind Tunnel Test

Acoustic wind tunnel test is an important way to study the noise mechanism of helicopter rotors. The broadband dipole noise distribution of helicopter rotors can be obtained from the acoustic wind tunnel measurement, which can be extremely helpful in analyzing the pulsation noise mechanism of rotor blade surfaces. However, during acoustic imaging of broadband dipole sources, there is often a problem of unwanted noise interference from other experimental setups of the wind tunnel, such as the rotor shaft. To accurately visualize the broadband dipole sound sources, in this paper, a moving dipole-type sources beamforming method suitable for the wind tunnel environment is proposed. The reduced-rank cyclic Wiener filter is firstly developed to extract the rotor broadband noise signal in wind tunnel tests; a beamforming method for moving dipole sound sources is then proposed according to the characteristics of the generation and propagation of the dipole sound sources. The BO105 helicopter rotor model is tested in the FL-17 aeroacoustic wind tunnel of the China Aerodynamics Research and Development Center (CADRC). The wind tunnel test results demonstrate that the method can effectively suppress noise interference in the wind tunnel and accurately extract and visualize broadband dipole sources of rotor blade surfaces.