Shuwen xu

Xidian University · school of electronic and engineering

A forest fire susceptibility map generated with the fire susceptibility model is the basis of fire prevention resource allocation. A more reliable susceptibility map helps improve the effectiveness of resource allocation. Thus, further improving the prediction accuracy is always the goal of fire susceptibility modeling. This paper developed a fores...

The reconstruction of time-varying signals on graphs is a prominent problem in graph signal processing community. By imposing the smoothness regularization over the time-vertex domain, the reconstruction problem can be formulated into an unconstrained optimization problem that minimizes the weighted sum of the data fidelity term and regularization...

In this paper, an approach for radar clutter, especially sea and land clutter classification, is considered under the following conditions: the average amplitude levels of the clutter are close to each other, and the distributions of the clutter are unknown. The proposed approach divides the dataset into two parts. The first data sequence from sea...

Fire risk prediction is significant for fire prevention and fire resource allocation. Fire risk maps are effective methods for quantifying regional fire risk. Laoshan National Forest Park has many precious natural resources and tourist attractions, but there is no fire risk assessment model. This paper aims to construct the forest fire risk map for...

This letter presents a generalized likelihood ratio test (GLRT)-based adaptive detector specially for the sub-Gaussian symmetric alpha-stable (SGS $\alpha \text{S}$ ) sea clutter background. Since the probability density function (PDF) of SGS $\alpha \text{S}$ distribution cannot be expressed as a closed-form expression in terms of the elementary...

Graph signal processing (GSP) is a field that deals with data residing on irregular domains, i.e. graph signals. In this field, the graph filter bank is one of the most important developments, owing to its ability to provide multiresolution analysis of graph signals. However, most of the current research on graph filter bank focuses on static graph...

Forest road network plays a key role in shortening the response time of firefighting activities. Therefore, evaluation and improvement of the ability of firefighting of the forest roads are essential. The widely used travel time criterion evaluation showed that firefighters can reach the areas of fires by walking and carrying portable fire equipmen...

Classification of clutter, especially in the context of shore based radars, plays a crucial role in several applications. However, the task of distinguishing and classifying the sea clutter from land clutter has been historically performed using clutter models and/or coastal maps. In this paper, we propose two machine learning, particularly neural...

In this paper, a multi-feature detector based on isolation forest (iForest) algorithm is developed to detect floating small targets in sea clutter. The conventional multi-feature detector can only process three features or less. The proposed detector aims to break the limitation of feature dimensions' number of the existed feature-based detectors a...

Radar external calibration is an important measurement in determining the radar cross sections of unknown targets and the reflectance coefficients of the sea surface. This measurement is often made in an anechoic chamber by standard programs. Sometimes, this measurement must be made in outdoor conditions, and the ambient environment severely affect...

Owing to the complicated characteristics of high-resolution sea clutter and the diversity of sea-surface small targets, there is no precise parameter model to describe sea clutter and returns with targets. As a result, target detection faces many obstacles. To distinguish sea clutter and target returns, it is effective to extract their features to...

Radar target detection in sea clutter is of significance to both civilian and military. With the miniaturization and invisibility of sea targets, floating small targets with slow speed have become the focus of radar detection. However, the detection of floating small targets in the background of sea clutter has always been a problem. Floating small...

Traditional human-vision-based watchtower systems are being gradually replaced by the machine-vision-based watchtower system. The visual range of machine-vision-based watchtower is smaller than the range of traditional human-vision-based watchtower, which has led to a sharp increase in the number of towers that should be deployed. Consequently, the...

The problem of target detection in impulsive non-Gaussian sea clutter has attracted a lot of attention in recent years. The positive alpha-stable (PαS) distribution has been validated as a suitable model for the impulsive non-Gaussian sea clutter. Since the probability density function (PDF) of the PαS variable cannot be expressed as a closed-form...

This work addresses the problem of detecting the changes between the two SAR images from the same region with two different phases. Because of the advantages of fast computing speed and high efficiency, the development of efficient and accurate algorithm for spatial change detection is always an important research issue in radar field. Unfortunatel...

Lots of detectors for high resolution range profile (HRRP) data are mainly based on the intensities of target echoes. When the intensities of outliers are as large as those of targets of interest, some false alarms will emerge in detection stage. In this paper, we propose a rejection algorithm for HRRP data between the detection stage and recogniti...

Wind direction factor, as a part of some empirical sea clutter models of the normalised radar cross-section (NRCS), is closely related to wind direction angle, grazing angle and radar wavelength. The use of the low-grazing-angle (LGA) sea clutter measured by UHF-band radar on the Lingshan island to discuss the characteristic of the wind direction f...

This paper addresses the problem of adaptive detection of radar targets embedded in heterogeneous compound-Gaussian clutter environments. Based on the Bayesian theory, a priori knowledge of clutter is utilized to improve detection performance. The clutter texture is modeled by the inverse Gaussian distribution to describe the heavy-tailed clutter....

This paper studies the design of efficient detector for radar targets in compound-Gaussian clutter with inverse Gaussian texture (CG-IG clutter). Due to inclusion of the modified Bessel function, the optimum coherent detector in CG-IG clutter cannot be easily implemented in radar systems. Through deriving the mathematical relationship between the s...

This paper considers the target detection problem in multiple-input multiple-output radar where the disturbance covariance matrix is unknown. Based on the Rao criterion, a persymmetric Rao test is designed by exploiting the persymmetric structure of the disturbance covariance matrix. Particularly, the proposed detector does not require training dat...

In this letter, a family of estimators based on truncated moments are proposed to estimate the parameters of compound-Gaussian model with inverse gamma texture. The truncated-moments estimation method generalizes the previous bi-percentile estimators, and the proposed estimator is robust to outliers. The experiments based on simulated and real sea...

In this letter, we focus on the statistical modeling of sea clutter amplitudes. Due to its non-Gaussian nature, the existing statistical models are sometimes difficult to represent well the heavy-tailed portion of amplitude distribution. To address this problem, we propose a compound Gaussian (CG) model with a generalized inverse Gaussian (GIG) tex...

In this paper, we consider the distributed target detection problem in Gaussian clutter with unknown covariance matrix. By exploiting the persymmetry of the covariance matrix, an adaptive detector is proposed according to the two-step design method. The probabilities of detection and false alarm of the proposed detector are derived in closed form,...

In the context of vehicular delay-tolerant networks (VDTNs), routing is critical to the overall performance and functionality of the network. With no static connection, and with a highly temporal network behavior, conventional routing techniques seldom work in the context of VDTNs. Techniques that leverage context information, such as position and...

This paper focuses on the range migration (RM) and Doppler frequency migration (DFM) corrections of the long-time coherent integration, and a fast algorithm is proposed for maneuvering target detection and motion parameters estimation under a low signal-to-noise ratio (SNR). By utilizing the autocorrelation function with respect to the slow time, n...

This letter addresses the feature detection design for the target embedded in sea clutter. Three polarization features (the relative surface scattering power, the relative volume scattering power, and the relative dihedral scattering power) are obtained based on the observed multipolarization channel returns. Then, 3-D feature detector is construct...

In this paper, we investigate the adaptive subspace detection of range-spread target embedded in compound Gaussian clutter. The inverse Gaussian distribution is considered to describe the texture of the clutter in order to match the non-Gaussian characteristic of sea clutter. Moreover, the range-spread target's energy is assumed to be spread not on...

The conventional methods for target detection and discrimination in high-resolution synthetic aperture radar (SAR) images usually have low accuracy and slow speed, especially for large complex scenes. To overcome these drawbacks, in this paper, we propose a target detection and discrimination method based on visual attention model. In the detection...

High-resolution sea clutter can be modeled by the compound-Gaussian model and its texture component determines the non-Gaussian characteristics of the clutter and the following detection algorithm. Traditional adaptive detectors assume that the texture is independent and identically distributed (IID) along the range, which loses sight of the textur...

This paper studies adaptive detection of radar targets embedded in generalized Pareto clutter on the condition with the limited secondary data. In order to alleviate the effects of the non-Gaussian characteristic of the clutter, a-priori knowledge of the non-Gaussian clutter is considered in the designed detector. More precisely, we consider that t...

In this paper, combined adaptive normalized matched filter (ANMF) detector is proposed to detect moving target in sea clutter. For the long integration time, moving target suffers from Doppler frequency changes in individual range cells, and the sea clutter is nonstationary along the pulse dimension. Therefore, ANMF detector is ineffective in this...

For the problem of detection performance loss of adaptive detectors on the condition that the secondary data are limited, the adaptive detection method of range-spread target based on the prior knowledge of clutter is proposed. The texture and the covariance matrix of speckle of clutter are respectively modeled as the random variable which follows...

It is always a difficult task for the marine surface surveillance radar to detect the floating small target embedded in the sea clutter. Considering the non-uniform and non-stationary nature of sea clutter, the block-whitening strategy is used to suppress the clutter. By analyzing the differences between the energy distributions of the clutter-only...

The detection problem of the sparse range-spread target against correlated non-Gaussian clutter is considered in this paper, and the clutter is modeled as the compound-Gaussian (CG) distribution. The CG clutter's texture is modeled as the square root of an inverse-gamma distribution, and the clutter's power obeys the generalized Pareto (GP) distrib...

The compound Gaussian clutter with the square root of inverse Gaussian texture component has been successfully used for modeling the heavy-tailed non-Gaussian clutter measured by high-resolution radars. In high-resolution radars, the targets may extend along multiple consecutive range cells, which are called range-spread targets. In this paper, we...

Parameters estimation is important for improving the detection performance of detectors. In this paper, we propose a novel estimation method for the parameters of compound-Gaussian distribution with inverse Gaussian texture. We obtain the moments estimation expressions of parameters of compound-Gaussian distribution with inverse Gaussian texture an...

A novel non-coherent detection scheme for range-spread targets in the sea clutter is developed in this study. The detector utilises the bi-window non-linear shrinkage map (BNSM) to reduce sea clutter while preserving target echoes before energy integration (EI). The EI detector based on BNSM (EI-BNSM) is compared with the conventional non-coherent...

In this paper, shape-parameter-dependent matched filter (MF) detectors are proposed for moving target detection in K-distributed clutter, which are specified by a single parameter α [0, 1], the α-MF detectors for short. The α-MF detectors include the MF and normalized matched filter (NMF) detectors as special examples with α = 0 and 1. The paramete...

A novel 2D non-local nonlinear shrinkage map (NLNSM) on 2D range-pulse image is proposed in this paper and it is imbedded into the geometric average integration (GAI) scheme to yield a new range-spread target detector in white Gaussian noise. Because the denoising ability of the NLNSM is better than that of the 2D local nonlinear shrinkage map (NSM...

It is always a challenging problem for marine surface surveillance radar to detect sea-surface floating small targets. Conventional detectors using incoherent integration and adaptive clutter suppression have low detection probabilities for such targets with weak returns and unobservable Doppler shifts. In this paper, three features of a received v...

Adaptive detection of range spread manoeuving target embedded in compound-Gaussian clutter is an important challenge for radar engineers. For the long integration, maneuvering target suffers from inevitable range walks across cells as well as unpredictable phase change at individual range cells. Therefore, the traditional adaptive normalized matche...

This paper proposes a waveform-cross-entropy (WCEN)-based detection scheme to detect manoeuvring range-spread targets in homogeneous weather clutter. The input of the detector is composed of complex-valued high resolution range profiles (HRRPs) from a train of coherent pulses in the observation window. The observation window contains a detection wi...

It is difficult for high resolution radar (HRR) to detect range-spread maneuvering targets in homogenous clutter. The traditional generalised likelihood ratio test (GLRT) detectors are ineffective in long integration duration, because maneuvering targets suffer from inevitable range walks across cells as well as unpredictable phase change at indivi...

The problem of two order statistics detection schemes for the detection of a spatially distributed target in white Gaussian noise are studied. When the number of strong scattering cells is known, we first show an optimal detector, which requires many processing channels. The structure of such optimal detector is complex. Therefore, a simpler quasi-...

In this study, a practically efficient method is proposed to detect range-spread targets of manoeuvring flight in white Gaussian noise. High-resolution range profiles (HRRPs) from multiple consecutive pulses are stacked into a two-dimensional (2D) greyscale range-pulse image along range cells and pulses. Based on the local statistics of the images,...

In this paper, a heuristic detector is proposed to detect range-spread targets in white Gaussian noise using multiple consecutive high- resolution range profiles (HRRPs) received from a high-resolution radar (HRR). The detector consists of refiners of HRRPs and a cross-correlation integrator of refined HRRPs. Based on the fact that strong scatterin...

In many practical applications, signals to be detected are unknown nonlinear frequency modulated (FM) and are corrupted by strong noise. The phase histories of the nonlinear FM signals are assumed to be unknown smooth functions of time, which are usually poorly modeled or cannot be modeled at all by a small number of parameters. Because of the lack...

Aimed at the shortage of the conventional hard threshold of the binary integrator, a new method based on the local fuzzy thresholding map is proposed. The new method utilizes the local fuzzy threshold in range dimension to suppress noise-only cells and preserve target's strong scattering cells. Then, the energy integration in the range-pulse domain...

A detection scheme for a range-spread target in white Gaussian noise is developed. The detector is based on waveform entropy of the arithmetic average of multiple successive high-resolution range profiles, and has the precious property of a constant false-alarm rate (CFAR). The proposed detector is compared with the conventional detectors based on...

A detection scheme for unknown nonlinear frequency modulated signals in white Gaussian noise is developed using the fractional Fourier transform and two-dimensional order-statistic filter. The simulation experiment and comparison with other methods available are shown, and the effectiveness of the proposed method is reported.

Double-pulse or multi-pulse detectors have better performance than single pulse detectors in inverse synthetic aperture radar (ISAR) system. The more echoes we use, the better performance we have if the optimum detectors are utilized. The conventional inter-period correlation processing (IPCP) utilizes the received echoes directly. In this paper, a...

In this paper, a new technique based on Gabor filters with adaptive window is proposed for SAR image segmentation in overcomplete brushlet domain. SAR image is full of texture and direction information, and brushlet is a new kind of analysis tool for image with rich directional information. Aim at these characteristics, this paper combines Gabor fi...