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- 2018
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- Brno University of Technology
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- Institut National Polytechnique Felix Houphou?t-Boigny Yamoussoukro
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Dynamical distortions of structural signatures in molecular high-order harmonic spectroscopy
摘要： We study the signature of two-center interferences in molecular high-order harmonic spectra, with an emphasis on the spectral phase. With the help of both ab initio computations based on the time-dependent Schr?dinger equation and the molecular strong-field approximation (SFA) as developed by Chiril? et al. [Phys. Rev. A 73, 023410 (2006)] and Faria [Phys. Rev. A 76, 043407 (2007)], we observe that the phase behavior is radically different for the short and the long trajectory contributions. By means of Taylor expansions of the molecular SFA, we link this effect to the dynamics of the electron in the continuum. More precisely, we find that the value of the electric field at recombination time plays a crucial role in the shape of the destructive interference phase jump.
关键词： molecular spectroscopy,spectral phase,strong-field approximation,two-center interferences,time-dependent Schr?dinger equation,high-order harmonic generation
更新于2025-09-23 15:23:52
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Remote Sensing: An Automated Methodology for Olive Tree Detection and Counting in Satellite Images
摘要： Cultivation of olive trees for the past few years has been widely spread across Mediterranean countries, including Spain, Greece, Italy, France, and Turkey. Among these countries, Spain is listed as the largest olive producing country with almost 45% of olive oil production per year. Dedicating land of over 2.4 million hectares for the olive cultivation, Spain is among the leading distributors of olives throughout the world. Due to its high signi?cance in the country’s economy, the crop yield must be recorded. Manual collection of data over such expanded ?elds is humanly infeasible. Remote collection of such information can be made possible through the utilization of satellite imagery. This paper presents an automated olive tree counting method based on image processing of satellite imagery. The images are pre-processed using the unsharp masking followed by improved multi-level thresholding-based segmentation. Resulting circular blobs are detected through the circular Hough transform for identi?cation. Validation has been performed by evaluating the proposed scheme for the dataset formed by acquiring images through the ‘‘El Sistema de Información Geográ?ca de Parcelas Agrícolas’’ viewer over the region of Spain. The proposed algorithm achieves an accuracy of 96% in detection. Computation time was recorded as 24 ms for an image size of 300 × 300 pixels. The less spectral information is used in our proposed methodology resulting in a competitive accuracy with low computational cost in comparison to the state-of-the-art technique.
关键词： crop estimation,multi-spectral imagery,Remote sensing,olive,Hough transform,satellite imagery
更新于2025-09-23 15:23:52
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An LDI-MSI approach for targeted and untargeted differentiation and assessment of pharmaceutical formulations
摘要： Falsified, counterfeit and adulterated medicines are an endemic problem worldwide that results in both monetary and health-related losses. Developing fast and reliable methods that are able to present a timely result based on the drug’s spectral profile is an effort that is sure to benefit those involved in the whole distribution chain. We propose herein a Laser Desorption/Ionization imaging-based method that provides simple and minimal sample preparation; this method is capable of providing specific markers that characterize adulterations, using as proof of concept one of the most adulterated drug products for oral use, sildenafil. Our approach is able to provide quality markers, which can be applied in the fast screening of any product within the same molecular class. This same strategy may be a useful alternative to provide accurate measurements with high specificity for unraveling contaminants and/or byproducts in virtually any given pharmaceutical product.
关键词： mass spectrometry imaging,LDI,direct analysis,spectral profiles,Falsified medicines
更新于2025-09-23 15:23:52
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A review on smart application of supplemental lighting in greenhouse fruiting vegetable production
摘要： Different spectra of light trigger different plant growth processes. Therefore, the optimum light spectrum for various plant physiological and growth processes may be different. For greenhouse fruiting vegetables, such as tomatoes, it is important to optimize light spectrum to promote canopy growth to increase light interception during the early stage of plant growth. Once the plants reach full canopy, the focus should be moved to optimizing vertical light distribution because most greenhouse fruiting vegetables are tall crops and the growth processes along the vertical profile are different; most of the canopy growth occurs in the top and middle canopy while fruit growth occurs in the middle and bottom canopy. Because the fruit, not the leaf, is the economic product, the optimized light spectral composition should enhance leaf carbon export and translocation to fruit to improve fruit yield and quality. Therefore, a research project was initiated in 2013 to identify proper light spectral composition and vertical distribution regimes for greenhouse fruiting vegetable production. Different overhead light sources (high-pressure sodium light with or without far-red light-emitting diode (LED) light, plasma light and different spectral compositions of LEDs) and several intra-canopy spectral compositions provided by LEDs were evaluated over four winters on tomatoes, mini-cucumbers and sweet peppers. The effects of light spectrum on whole-plant net carbon exchange and leaf carbon export using 14C-isotype tracing were also investigated. The vertical light regimes resulted in significant differences in leaf photosynthetic rate, leaf size, fruit yield and fruit quality in greenhouse tomatoes, mini-cucumbers and sweet peppers. Proper vertical light regimes were identified for hybrid light systems (overhead high intensity discharge light + intra-canopy LEDs) and for pure LED light systems (overhead + intra-canopy LEDs). This review clearly demonstrates that optimized vertical light regimes can be developed for improving both plant growth and fruit yield and quality in year-round greenhouse fruiting vegetable production.
关键词： far-red light,Solanum lycopersicum,Capsicum annuum,Cucumis sativus,light quality,vertical light spectral distribution,temperature,LED,lighting,spectral composition
更新于2025-09-23 15:22:29
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[IFIP Advances in Information and Communication Technology] Computer and Computing Technologies in Agriculture X Volume 509 (10th IFIP WG 5.14 International Conference, CCTA 2016, Dongying, China, October 19–21, 2016, Proceedings) || Modelling and Predicting of Soil Electrical Conductivity and PH from Semi-arid Grassland Using VIS-NIR Spectroscopy Technology
摘要： The electrical conductivity (EC) and pH value are key indicators for soil physical and chemical properties, which can re?ect the level of soil acid and alkali, furthermore, in?uence the vegetation growth. The spectroscopy technique can estimate and evaluate electrical conductivity and pH value rapidly and ef?ciently, which can provide useful information on the real-time soil management in the semi-arid rangeland or grassland. We picked the semi-arid grassland of northern China covering an area about 200 km2 as the target research area, given that it is highly sensitive to grazing and mining affect. Soil samples were collected from 72 sampling sites in this area, which covered grazing exclusion, over grazing and grassland restoration area. The SVC HR-1024 spectroradiometer was used to acquire soil spectrum. This study aims to indicate the spectral characteristic for soil EC and pH, and propose a predicting modeling method with optimal input spectral region and transformation by comparing the support vector machine (SVM) regression method and partial least squares (PLSR) regression modeling method. Our results showed that: (1) once EC value is larger than 0.10 ls/m, the soil spectral re?ectance decreases with increasing of EC value. The absorption depth, width and area at 1900 nm reduce with increasing of EC value as well; (2) There are positive correlation between EC, pH value and soil spectral re?ectance. The highest correlation coef?cient value of 0.7 between pH and re?ectance is recorded at visible region around 500 nm; (3) The SVM modeling method produce the higher prediction accuracy (RPD = 2.18, RMSE = 0.035, R2 = 0.78 for EC, RPD > 3, RMSE = 0.349, R2 = 0.91 for pH) rather than PLSR methods in soil EC and pH prediction. This study indicated that it was possible to use the spectroradiometer technology to predict EC and pH value for the soil from semi-arid grassland, which would provide the basis for soil acid and alkali detecting using hyper-spectral remote sensing technology.
关键词： Semi-arid grassland,Spectral modeling and predicting,Soil electrical conductivity and pH,Spectral characteristic
更新于2025-09-23 15:22:29
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Tomodensitométrie spectrale?: de la double énergie à la multiénergie
摘要： Standard computed tomography imaging allows the differentiation between anatomic structures based on their X-ray global attenuation difference. This difference, due to the Compton and photoelectric effects, depends essentially on the effective atomic number and electronic density of the elements evaluated. Spectral dual energy CT expends the capabilities of standard CT by distinguishing elements of same attenuation by their difference of Compton and photoelectric effects. The purpose of this didactic content is to introduce principles and explain the technology of spectral CT imaging, based on the attenuation difference at two different energies. Moreover, evolutions towards spectral multienergy CT will be introduced.
关键词： K-edge,Dual energy CT,Spectral CT,Spectral photon-counting CT,Contrast agents,Virtual monoenergetic image
更新于2025-09-23 15:22:29
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Enrichment of the Satellitesceneontology with Hyperspectral Images/ Crops and Feature Vectors of Radiometric Indices
摘要： Semantic classification and annotation of satellite images are of great importance and require knowledge resources. The complexity of satellite scenes makes its classification and annotation hard tasks and we are still far from totally resolving the semantic gap problem. There are several knowledge resources such as semantic networks, taxonomies and ontologies. In this paper, we propose to enrich the Satellite Scene Ontology using real hyperspectral scenes, the USGS spectral library and the WordNet lexical database. The resulting ontology would be published online for further exploitation by researchers.
关键词： WordNet,Radiometric Indices,Satellite Scene Ontology,Ontology,Hyperspectral Images (HSI),Spectral Signature,USGS Spectral Library
更新于2025-09-23 15:22:29
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Spectral Zooming and Resolution Limits of Spatial Spectral Compressive Spectral Imagers
摘要： The recently introduced Spatial Spectral Compressive Spectral Imager (SSCSI) has been proposed as an alternative to carry out spatial and spectral coding using a binary on-off coded aperture. In SSCSI, the pixel pitch size of the coded aperture, as well as its location with respect to the detector array, play a critical role in the quality of image reconstruction. In this paper, a rigorous discretization model for this architecture is developed, based on a light propagation analysis across the imager. The attainable spatial and spectral resolution, and the various parameters affecting them, is derived through this process. Much like the displacement of zoom lens components leads to higher spatial resolution of a scene, a shift of the coded aperture in the SSCSI in reference to the detector leads to higher spectral resolution. This allows the recovery of spectrally detailed datacubes by physically displacing the mask towards the spectral plane. To prove the underlying concepts, computer simulations and experimental data are presented in this paper.
关键词： discretization model,spatial resolution,coded aperture,Spectral imaging,compressive sensing,spectral resolution
更新于2025-09-23 15:22:29
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[IEEE 2018 International Conference on Communication and Signal Processing (ICCSP) - Chennai (2018.4.3-2018.4.5)] 2018 International Conference on Communication and Signal Processing (ICCSP) - A Comparative Analysis of Total Variation and Least Square Based Hyperspectral Image Denoising Methods
摘要： Hyperspectral image (HSI) with high spectral resolution will be always degraded by the noise accumulation. Therefore, image denoising is a fundamental preprocessing technique which improves the precision of successive processes like image classification, unmixing etc. In this paper, we compare least square (LS) weighted regularization in spectral domain with spatial least square and total variation (TV) denoising techniques. These methods are experimented on real, and noise simulated hyperspectral image datasets. The contrast and edges of the image are well preserved in the spectral LS. The image contrast varies in spatial LS, and edge informations are lost in TV. The experimental results show that, the spectral LS is superior to other two techniques in terms of visual interpretation, Signal-to-Noise Ratio (SNR) and Structural Similarity (SSIM) Index.
关键词： IBBC,SNR,Least Square,Hyperspectral Image,Denoising,Spectral domain,Total Variation,SSIM
更新于2025-09-23 15:22:29
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Automatic and Unsupervised Water Body Extraction Based on Spectral-Spatial Features Using GF-1 Satellite Imagery
摘要： Water body extraction from remote sensing imagery is an essential and nontrivial issue due to the complexity of the spectral characteristics of various kinds of water bodies and the redundant background information. An automatic multifeature water body extraction (MFWE) method integrating spectral and spatial features is proposed in this letter for water body extraction from GF-1 multispectral imagery in an unsupervised way. This letter first discusses a spatial feature index, called the pixel region index (PRI), to describe the smoothness in a local area surrounding a pixel. PRI is advantageous for assisting the normalized difference water index (NDWI) in detecting major water bodies, especially in urban areas. On the other hand, part of the water pixels near the borders may not be included in major water bodies, k-means clustering is subsequently conducted to cluster all the water pixels into the same group as a guide map. Finally, the major water bodies and the guide map are merged to obtain the final water mask. Our experimental results demonstrate that accurate water masks were achieved for all seven GF-1 imagery scenes examined. Three images with a complex background and water conditions were used to quantitatively compare the proposed method to NDWI thresholding and support vector machine classification, which verified the higher accuracy and effectiveness of the proposed method.
关键词： water body extraction,image classification,spectral-spatial feature,GF-1 imagery
更新于2025-09-23 15:22:29