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- 2018
- 2015
- classification
- Fruit defects
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- Hyperspectral imaging
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- plant cell diseases
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- Applied Physics
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- Brno University of Technology
- University of Sciences, Technique and Technology Bamako
- Mohammed V University in Rabat
- Southern Taiwan University of Science and Technology
- Institut National Polytechnique Felix Houphou?t-Boigny Yamoussoukro
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A novel endmember extraction method using sparse component analysis for hyperspectral remote sensing imagery
摘要： The spectral unmixing (SU) technique is an effective method of solving the mixed pixel problem in the hyperspectral remote sensed imagery (HSI). During the process, endmember extraction algorithm (EEA) is significant for the creation of material abundance maps. However, the traditional EEAs are not very reliable due to the low resolution of sensor and the complex diversity of land cover feature distribution. In addition, the mutually independent endmember assumption will be affected accordingly. In order to overcome the above limitations, a novel endmember extraction method using sparse component analysis for hyperspectral remote sensing imagery (EESCA) has been presented in this paper. EESCA assumes that each pixel in the image scene is a sparse linear mixture of all endmembers. First, the hyperline clustering algorithm is incorporated to consider the subspace clustering of all pixels after the initialization of endmember mixing matrix. It enlarges differences among ground objects and helps finding endmembers with smaller spectrum divergences. After that, the K-SVD is proposed to search the real endmembers for sparse representations with coefficients summarized in the mixing matrix. The method transfers the pure endmember extraction problem into an optimization problem by minimizing the residual errors. Four state-of-the art methods are implemented to make comparisons with the performance of EESCA. The robustness of the proposed algorithm is verified through both simulated images and real satellite images. Experimental results show that the EESCA outperforms other methods in spectral angle distance (SAD) and root-mean-square-error (RMSE), and especially could identify accurate endmembers for ground objects with smaller spectrum divergences.
关键词： sparse component analysis,endmember extraction,Hyperspectral imagery,spectral unmixing
更新于2025-09-10 09:29:36
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Broad-range ultrafast all-optical red-shifting of EUV surface plasmons: Proof-of-principle and advanced surface nanotexturing in aluminum
摘要： Using aluminum as an example, ultrafast sub-ablative broad-range (EUV-IR) spectral tuning of surface plasmon resonance in metals by IR femtosecond laser pulses was demonstrated by theoretical modeling of prompt surface optics for strongly photoexcited materials and of their surface plasmon-polariton (SPP) dispersion curves, as well as by experimental multi-shot laser imprinting of surface plasmon-polaritons as large-scale regular surface ripples with minimal sub-di?raction periods down to 200 nm. According to laser-pump self-re?ection and charge emission experiments, the key issue in the prompt optical tuning (spectral red-shifting) of EUV surface plasmon resonance in aluminum by the IR laser pulses is related to ultrafast surface charging of its surface via intense electron emission during the laser pump pulse, depleting its surface electron density and simultaneously decreasing its surface/bulk plasma frequencies, at the corresponding negligible surface ablative etching.
关键词： Surface nanoripples,Femtosecond laser excitation,Spectral tuning,EUV surface plasmon resonance,Electronic heating and charging,Aluminum
更新于2025-09-10 09:29:36
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia, Spain (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Hyperspectral Endmember Extraction Preprocessing Using Combination of Euclidean and Geodesic Distances
摘要： Combination the spatial-contextual information in spectral unmixing as a preprocessing of endmember extraction algorithms (EEAs) has been an important issue in hyperspectral image analysis. Particularly, this paper performs a new preprocessing framework using combination of spectral Geodesic and spatial Euclidean distances prior to classical spectral-based EEAs. It exploits both spatial and spectral features of image pixels in order to look for high spectrally correlated and spatially homogenous regions where pure spectral signatures are more likely to be found. For this purpose, it exerts a new correlation coefficient quantity on spatially homogenous pixels designated by spectral weighting determination and appraising the cluster label of spatial neighbours of pure pixels. The novel preprocessing hampers from useless computation of a great number of mixed pixels executed by EEAs. Additionally, two new spectral Geodesic and spatial Euclidean distances are presented to specify the final mean vector which exploits in correlation coefficient computations. The validation of our preprocessing is deliberated on two real hyperspectral datasets from the viewpoints of RMSE and SAD based errors in comparison with other schemes. Experimental consequences declare that such preprocessing can amend figures of unmixing accuracy without intensifying the complexity and with no requirement of changing EEAs.
关键词： endmember,spectral,preprocessing,Euclidean,spatial,Geodesic
更新于2025-09-10 09:29:36
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Detection of <i>Firmiana danxiaensis</i> Canopies by a Customized Imaging System Mounted on an UAV Platform
摘要： The objective of this study was to test the effectiveness of mapping the canopies of Firmiana danxiaensis (FD), a rare and endangered plant species in China, from remotely sensed images acquired by a customized imaging system mounted on an unmanned aerial vehicle (UAV). The work was conducted in an experiment site (approximately 10 km2) at the foot of Danxia Mountain in Guangdong Province, China. The study was conducted as an experimental task for a to-be-launched large-scale FD surveying on Danxia Mountain (about 200 km2 in area) by remote sensing on UAV platforms. First, field-based spectra were collected through hand-held hyperspectral spectroradiometer and then analyzed to help design a classification schema which was capable of differentiating the targeted plant species in the study site. Second, remote-sensed images for the experiment site were acquired and calibrated through a variety of preprocessing steps. Orthoimages and a digital surface model (DSM) were generated as input data from the calibrated UAV images. The spectra and geometry features were used to segment the preprocessed UAV imagery into homogeneous patches. Lastly, a hierarchical classification, combined with a support vector machine (SVM), was proposed to identify FD canopies from the segmented patches. The effectiveness of the classification was evaluated by on-site GPS recordings. The result illustrated that the proposed hierarchical classification schema with a SVM classifier on the remote sensing imagery collected by the imaging system on UAV provided a promising method for mapping of the spatial distribution of the FD canopies, which serves as a replacement for field surveys in the attempt to realize a wide-scale plant survey by the local governments.
关键词： UAV,SVM,hierarchical classification,Firmiana danxiaensis,spectral analysis,remote sensing,image segmentation,vegetation indices
更新于2025-09-10 09:29:36
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia, Spain (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Dual-Channel Densenet for Hyperspectral Image Classification
摘要： Deep neural networks provide deep extracted features for image classification. As a high dimension data, hyperspectral image (HSI) feature extraction is unlike an RGB image whose feature representation could not be simply generated in the spatial domain. To take full advantage of HSI, a dual-channel convolutional neural network (CNN) is applied, 1D convolution for the spectral domain and 2D convolution for spatial domain. For pixel-wise classification of HSI, in our network model, one-dimensional customized DenseNet is for extracting the hierarchical spectral features and another customized DenseNet is applied to extract the hierarchical spatial-related feature. Furthermore, we experimentally tuned the several widen factors and dense-net growth rates to evaluate the impact of hyper-parameter. To compare our proposed method with HSI classification methods, we test other three DNNs based method in two real-world HSI dataset. The result demonstrated our approach outperformed the state-of-art method.
关键词： Dual-channel DenseNet,Hyperspectral image classification,spatial-spectral
更新于2025-09-10 09:29:36
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia, Spain (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Extendibility of a Thin-Cloud Removal Algorithm to Hi-Resolution Visible Bands of Sentinel-2 Data
摘要： The RTM-based algorithm developed to remove thin-cloud effects for Landsat-8 visible bands was extended to those of Sentine-2A visible bands. In the assessment of the extendibility, a cloud-covered Sentinel-2A image acquired on 18 February 2017 was downloaded. Another cloud-free Sentinel-2A image of the same area acquired on 8 February 2017 was selected as reference image. The three assumptions made in the original RTM-based algorithm were evaluated, and were valid for Sentinel-2A data. The algorithm was qualitatively and quantitatively effective in the thin-cloud removal for Sentinel-2A data of visible bands. Therefore, the algorithm developed for Landsat sensors was directly applicable to Sentinel-2 spectral data.
关键词： RTM-based algorithm,Thin clouds removal,Sentinel-2 spectral bands
更新于2025-09-10 09:29:36
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[IEEE 2018 VII. Lighting Conference of the Visegrad Countries (Lumen V4) - Trebic, Czech Republic (2018.9.18-2018.9.20)] 2018 VII. Lighting Conference of the Visegrad Countries (Lumen V4) - Public Lighting, Public Health
摘要： Impact of artificial light at night on sleep and health of humans and other living species is discussed among scientists. This paper analyses the properties of several commercially available light sources with regards to their effects on wildlife, human sleep, and health. A novel, environmentally considerate LED light source is introduced. Further, integration of this light source into the pilot biodynamic street lighting system is described. Based on the season and time of day, a control system changes the spectral composition of the light in lighting without compromising on safety, psychological needs or energy savings.
关键词： advanced control system,spectral power distribution,light at night,LED,biodynamic lighting,non-image forming light perception,Circadian rhythm
更新于2025-09-10 09:29:36
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Synthesis, crystal growth, structural, spectral, thermal, optical characteristics and density functional theory calculations of a novel third-order nonlinear optical material: 4-acetylanilinium dihydrogen phosphate (4AADP) single crystals
摘要： Single crystals of 4-acetylanilinium dihydrogen phosphate (4AADP), a novel third-order nonlinear optical material has been synthesized and successfully grown by the slow evaporation solution growth technique using acetone as a solvent at room temperature. The single crystal X-ray diffraction analysis implies that 4AADP crystallized into a monoclinic crystal system with the centrosymmetric space group P21/c. The molecular structure of the grown 4AADP compound was evidently established by using 1H and 13C NMR spectral analysis. The vibrational behavior of the chemical bond and discrete functional groups of the grown crystal were identified using FT-IR and FT-Raman spectral analysis. UV-Visible-Near Infrared spectral analysis shows that the grown crystal was highly transparent in the entire visible range above 365 nm. The 4AADP compound was thermally stable up to 195 oC and it was ascertained by thermogravimetric and differential scanning calorimetric analysis. The photoactive behavior of the material was established from photoluminescence studies. The ionization energy (I) and electron affinity (A) were computed from the energy gap values of HOMO and LUMO orbitals respectively. The Molecular electrostatic potentials and Mulliken charges have also been calculated theoretically by applying DFT/B3LYP method. The nonlinear absorption coefficient (β), third order nonlinear refractive index (n2) and third-order nonlinear optical susceptibility (χ3) were calculated from Z-scan measurements, reveals that the grown crystal of 4AADP could serve as a promising source for nonlinear optical devices.
关键词： Crystal growth,Density functional theory,Z-scan,Thermal analysis,Spectral studies
更新于2025-09-10 09:29:36
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Numerical methods for the nonlocal wave equation of the peridynamics
摘要： In this paper we will consider the peridynamic equation of motion which is described by a second order in time partial integro-differential equation. This equation has recently received great attention in several fields of Engineering because seems to provide an effective approach to modeling mechanical systems avoiding spatial discontinuous derivatives and body singularities. In particular, we will consider the linear model of peridynamics in a one-dimensional spatial domain. Here we will review some numerical techniques to solve this equation and propose some new computational methods of higher order in space; moreover we will see how to apply the methods studied for the linear model to the nonlinear one. Also a spectral method for the spatial discretization of the linear problem will be discussed. Several numerical tests will be given in order to validate our results.
关键词： Trigonometric time discretization,Peridynamic equation,Quadrature formula,Spectral methods
更新于2025-09-10 09:29:36
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Detection of gastric cancer and its histological type based on iodine concentration in spectral CT
摘要： Background: Computed tomography (CT) imaging is the most common imaging modality for the diagnosis and staging of gastric cancer. The aim of this study is was to prospectively explore the ability of quantitative spectral CT parameters in the detection of gastric cancer and its histologic types. Methods: A total of 87 gastric adenocarcinoma (43 poorly and 44 well-differentiated) patients and 36 patients with benign gastric wall lesions (25 inflammation and 11 normal), who underwent dual-phase enhanced spectral CT examination, were retrospectively enrolled in this study. Iodine concentration (IC) and normalized iodine concentration (nIC) during arterial phase (AP) and portal venous phase (PP) were measured thrice in each patient by two blinded radiologists. Moreover, intraclass correlation coefficient (ICC) was used to assess the interobserver reproducibility. Differences of IC and nIC values between gastric cancer and benign lesion groups were compared using Mann-Whitney U test. Furthermore, the gender, age, location, thickness and histological types of gastric adenocarcinoma were analyzed by Mann-Whitney U test or Kruskal-Wallis H test. Receiver operating characteristic (ROC) curves were used to evaluate the diagnostic efficacy of IC and nIC values, and the optimal cut-off value was calculated with Youden J. Results: An excellent interobserver agreement (ICC > 0.6) was achieved for IC. Notably, the values of ICAP, ICPP, nICAP and nICPP were significantly higher in gastric cancer group (Z = 5.870, 3.894, 2.009 and 10.137, respectively; P < 0.05) than those in benign lesion group. Additionally, the values of ICAP, ICPP, nICAP and nICPP were significantly higher in poorly differentiated gastric adenocarcinoma group (Z = 4.118, 5.637, 6.729 and 2.950, respectively; P < 0.005) than those in well-differentiated gastric adenocarcinoma group. There were no statistically significant differences in the values of ICAP, ICPP, nICAP and nICPP between age, gender, tumor thickness and tumor location. Furthermore, the area under the curve (AUC) values of ICAP, nICAP, ICPP and nICPP were 0.745, 0.584, 0.662, and 0.932, respectively, for gastric cancer detection; while 0.756, 0.919, 0.851 and 0.684, respectively, in discriminating poorly differentiated gastric adenocarcinoma. Conclusion: IC values exhibited great potential in the preoperative and non-invasive diagnosis of gastric cancer and its histological types. In particular, nICPP is more effective for the identification of gastric cancer, whereas nICAP is more effective in discriminating poorly differentiated gastric adenocarcinoma.
关键词： Adenocarcinoma,Gastric,Iodine concentration,Histological degree,Spectral CT imaging
更新于2025-09-10 09:29:36