- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
[IEEE 2018 International Conference on Radar (RADAR) - Brisbane, Australia (2018.8.27-2018.8.31)] 2018 International Conference on Radar (RADAR) - Radar Cross Section of Modified Target Using Gaussian Beam Methods: Experimental Validation
摘要： The aim of this paper is to study the Radar Cross Section (RCS) of modified radar targets (plate with notch) using Gaussian Beam techniques. The Gaussian methods used in this work are Gaussian Beam Summation (GBS) and Gaussian Beam Launching (GBL). We establish the theoretical formulation of the GBS and GBL techniques and analyze the influence of the main Gaussian beam parameters on the variation of the scattered field. Then, we present the simulations of RCS. The numerical results are compared with PO, MoM methods, and also with experimental measurements performed in the anechoic chamber at Lab-STICC (ENSTA Bretagne).
关键词： Radar Cross Section (RCS),Physical Theory of Diffraction (PTD),Physical Optic (PO),Gaussian Beam Summation (GBS),Gaussian Beam Launching(GBL),Method of Moment (MoM)
更新于2025-09-23 15:22:29
-
Noise Estimation for Image Sensor Based on Local Entropy and Median Absolute Deviation
摘要： Noise estimation for image sensor is a key technique in many image pre-processing applications such as blind de-noising. The existing noise estimation methods for additive white Gaussian noise (AWGN) and Poisson-Gaussian noise (PGN) may underestimate or overestimate the noise level in the situation of a heavy textured scene image. To cope with this problem, a novel homogenous block-based noise estimation method is proposed to calculate these noises in this paper. Initially, the noisy image is transformed into the map of local gray statistic entropy (LGSE), and the weakly textured image blocks can be selected with several biggest LGSE values in a descending order. Then, the Haar wavelet-based local median absolute deviation (HLMAD) is presented to compute the local variance of these selected homogenous blocks. After that, the noise parameters can be estimated accurately by applying the maximum likelihood estimation (MLE) to analyze the local mean and variance of selected blocks. Extensive experiments on synthesized noised images are induced and the experimental results show that the proposed method could not only more accurately estimate the noise of various scene images with different noise levels than the compared state-of-the-art methods, but also promote the performance of the blind de-noising algorithm.
关键词： additive white Gaussian noise,local gray statistic entropy,image sensor,Poisson-Gaussian noise,noise estimation,local median absolute deviation
更新于2025-09-23 15:22:29
-
[IEEE 2018 OCEANS - MTS/IEEE Kobe Techno-Ocean (OTO) - Kobe, Japan (2018.5.28-2018.5.31)] 2018 OCEANS - MTS/IEEE Kobe Techno-Oceans (OTO) - Modeling Reflection Loss of the Gaussian Rough Ocean Surface
摘要： Modeling the acoustic reflection loss at the rough ocean surface is a necessary component of a sonar transmission model when the scattering field is mainly forward scattering and focuses on the specular direction. To modeling the reflection loss at small angles is of great significance for acoustic field predictions at meduim-to-long ranges ,especially for shallow oceans or oceans with a surface duct. Firstly, based on the rough ocean surface of Gaussian spectrum, the validity of Ramsurf acoustic propagation model under rough surface conditions is demonstrated through comparison with the trial data in high state. Moreover, using the modified PE code—Ramsurf as a benchmark, Kirchhoff Approximation (KA) Reflection Loss (RL) model and Small Slope Approximation (SSA) RL model are compared and analyzed. The numerical simulation implies that the SSA model and results by Ramsurf match well.
关键词： rough sea surface,Small slope Approximation,reflection loss,Kirchhoff Approxiamtion,Gaussian spectrum
更新于2025-09-23 15:22:29
-
[IEEE 2018 3rd International Conference for Convergence in Technology (I2CT) - Pune (2018.4.6-2018.4.8)] 2018 3rd International Conference for Convergence in Technology (I2CT) - Modified Level-Set for Segmenting Breast Tumor from Thermal Images
摘要： Contactless, painless and radiation-free thermal imaging technique is one of the preferred screening modalities for detection of breast cancer. However, poor signal to noise ratio and the inexorable need to preserve edges defining cancer cells and normal cells, make the segmentation process difficult and hence unsuitable for computer aided diagnosis of breast cancer. This work uses a modified version of level-set called marker-controlled level-set for segmentation along with pre-processing. This paper presents key findings from a research conducted on the appraisal of two promising techniques, for the detection of breast cancer: a) marker-controlled Level-set segmentation of anisotropic diffusion filtered preprocessed image versus b) Segmentation using marker-controlled level-set on a Gaussian-filtered image. The proposed method was carried out on images from an online database with samples collected from women of varying breast characteristics. It was observed that the breast was able to be segmented out from the background by adjustment of the markers. From the results, it was observed that as a pre-processing technique, anisotropic filtering with level-set segmentation, preserved the edges more effectively than Gaussian filtering. Segmented image, by application of anisotropic filtering was found to be more suitable for feature extraction, enabling automated computer aided diagnosis of breast cancer.
关键词： Breast,Thermograms,Gaussian,Anisotropic diffusion,Segment,Level set
更新于2025-09-23 15:22:29
-
Synthesis and Properties of Novel Fluorescence Probe Based on 1,8-Naphthalimide for Detection of Hydrogen Sulfide
摘要： Two fluorescence-enhanced probes, 4-(2,4-dinitrophenoxy)-N-(2-hydroxyethyl)-1,8-naphthalimide(NTE-1) and 4-(2,4-dinitrophenoxy)-N-(4-(2,4-dinitrophenoxy)phenyl)-1,8-naphthalimide(NTE-2), have been designed and synthesized for detection of H2S. 4-Hydroxy-1,8-naphthalimide as fluorophore in combination with 2,4-dinitrophenyl ether as H2S response site constructed the fluorescence probes. The consequences showed that both NTE-1 and NTE-2 displayed large red-shift(excess 100 nm) in absorption spectra and more than 30-fold fluorescence enhancement in response to H2S. Moreover, the dual site probe, NTE-2, displayed wider linear range between fluorescence intensity and concentration of H2S(0—40 μmol/L) compared with single site probe, which can be applied to quantitative detection of high concentration of H2S. The photoinduced electron transfer(PET) response mechanism of probe was further studied by analyzing the distributions of molecular orbital. Importantly, the probes have potential practical applications in detection of H2S.
关键词： 2,4-Dinitrophenyl ether,Photoinduced electron transfer,Gaussian,Dual site
更新于2025-09-23 15:22:29
-
Unsupervised Segmentation of Spectral Images with a Spatialized Gaussian Mixture Model and Model Selection
摘要： In this article, we describe a novel unsupervised spectral image segmentation algorithm. This algorithm extends the classical Gaussian Mixture Model-based unsupervised classification technique by incorporating a spatial flavor into the model: the spectra are modelized by a mixture of K classes, each with a Gaussian distribution, whose mixing proportions depend on the position. Using a piecewise constant structure for those mixing proportions, we are able to construct a penalized maximum likelihood procedure that estimates the optimal partition as well as all the other parameters, including the number of classes. We provide a theoretical guarantee for this estimation, even when the generating model is not within the tested set, and describe an efficient implementation. Finally, we conduct some numerical experiments of unsupervised segmentation from a real dataset.
关键词： Spectral images,Gaussian Mixture Model,Model selection,Spatial information,Unsupervised segmentation
更新于2025-09-23 15:22:29
-
Frozen Gaussian approximation for high frequency wave propagation in periodic media
摘要： Propagation of high-frequency wave in periodic media is a challenging problem due to the existence of multiscale characterized by short wavelength, small lattice constant and large physical domain size. Conventional computational methods lead to extremely expensive costs, especially in high dimensions. In this paper, based on Bloch decomposition and asymptotic analysis in the phase space, we derive the frozen Gaussian approximation for high-frequency wave propagation in periodic media and establish its converge to the true solution. The formulation leads to ef?cient numerical algorithms, which are presented in a companion paper [SIAM J. Sci. Comput. 38 (2016), A2440–A2463].
关键词： lattice potential,high-frequency wave propagation,Bloch decomposition,Frozen Gaussian approximation
更新于2025-09-23 15:22:29
-
Advanced Studies in Pure Mathematics [Mathematical Society of Japan Singularities in Generic Geometry and Applications (Valencia IV) - Kobe & Kyoto, Japan ()] Singularities in Generic Geometry - Singularity analysis of lightlike hypersurfaces of partially null curves
摘要： We have gotten singularity classifications of lightlike hypersurfaces of a pseudo null curve in R4[6]. This paper is to characterize singularities of lightlike hypersurfaces of a partially null curve in the same space and give an example of such curves.
关键词： lightlike hypersurface,partially null curve,Gaussian surface,semi-Euclidean 4-space with index 2
更新于2025-09-23 15:22:29
-
Bandwidth-limited orbital angular momentum mode of Bessel Gaussian beams in the moderate to strong non-Kolmogorov turbulence
摘要： We investigate the effects of the moderate to strong fluctuation on the propagation of orbital angular momentum (OAM) modes carried by Bessel Gaussian beams in turbulent atmosphere. The analytic expression of the received probability of the signal and crosstalk OAM mode is derived based on the theories of extended Rytov and non-Kolmogorov turbulence. Our results show that turbulence with smaller non-Kolmogorov index, smaller inner-scale factor is more easily to induce OAM crosstalk between modes. With the increase of turbulence strength, the OAM spreads from adjacent modes to peripheral modes. Our results also indicate that the received signal intensity can be improved by use of Bessel Gaussian beams with small initial radii of beam, low OAM quantum number and long wavelength.
关键词： Bandwidth-limited mode,Non-Kolmogorov turbulence,Extended Rytov theory,Bessel Gaussian beam,Orbital angular momentum
更新于2025-09-23 15:22:29
-
Joint Color Space GMMs for CFA Demosaicking
摘要： We propose a patch-based algorithm for demosaicking a mosaicked color image produced by color filter arrays commonly used in acquiring color images. The proposed algorithm exploits a joint color space Gaussian mixture model (JCS-GMM) prior for jointly characterizing the patches from red, green, and blue channels of a color image. The inter channel correlations captured by the covariance matrices of Gaussian models are exploited to estimate the pixel values missing in the mosaicked image. The proposed JCS-GMM demosaicking algorithm can be seen as the GMM analogue of the Color-KSVD algorithm, which has produced impressive results in color image denoising and demosaicking. We demonstrate that our proposed algorithm achieves superior performance in the case of Kodak and Laurent Condat’s databases, and competitive performance in the case of IMAX database, when compared with state-of-the-art demosaicking algorithms.
关键词： Color filter array,demosaicking,Bayer pattern,Gaussian mixture models
更新于2025-09-23 15:22:29