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- 2018
- 2015
- classification
- Fruit defects
- Jujube
- Principal component analysis
- Hyperspectral imaging
- Xanthomonas oryzae
- multispectral and multimodal microscopy
- spectroscopic imaging
- plant cell diseases
- rice
- Optoelectronic Information Science and Engineering
- Applied Physics
- Measurement and Control Technology and Instruments
- 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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Distinguishing between closely related species of Allium and of Brassicaceae by narrowband hyperspectral imagery
摘要： Classification of crop species is an actively studied topic in remote sensing using multi-spectral image sensors. Unfortunately, the spectral bands available in the multispectral imagery are broad and limited in number to classify the crop species. In this paper, we propose optimal spectral bands to classify Allium (garlic and onion) and Brassicaceae (Chinese cabbage and radish) by using higher-dimensional data from hyperspectral imagery. A decision-tree classifier was used to determine the optimal method to use the high-dimensional data. The high-dimensional data were analysed for all growth stages and considering bandwidths with different full width at half maximum (FWHM) values at 25, 40, 50 and 80 nm. The spectral bands selected for Allium were differentiated into green, blue, and NIR bands for each growth stage. The results show that Allium can be classified clearly as overall accuracy (OA) 1 and kappa coefficient 1 for all FWHM based on March 22 data. For each April 19 and May 12 data, the decision-tree classifier with each 80 nm FWHM and 50 nm FWHM yielded a better classification accuracy of more than OA 0.921 and kappa coefficient 0.839 than other FWHM. The spectral bands selected for Brassicaceae were found to be similar to blue band for all growth stages. Brassicaceae was classified clearly for all FWHM based on October 27 data. Also, Brassicaceae was classified clearly for 25 nm FWHM based on November 25 data and OA, kappa coefficient for 40 nm FWHM and 50 nm FWHM are high as 0.974, 0.947 respectively.
关键词： Decision-tree classifier,Hyperspectral imagery,Classification,Full width at half maximum,Spectral band
更新于2025-09-23 15:23:52
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{μ-Bis(diphenylphosphino)methane}(1-alkyl-2-(arylazo)imidazole) copper(I) perchlorate : Synthesis, Structure and Photochromism
摘要： 1-Alkyl-2-(arylazo)imidazole (RaaiR/), a bidentate N(azo), N(imidazolyl) chelator, and bis(diphenylphosphino)methane (dppm), a P, P bridger, have been used to prepare phosphino bridged dinuclear-Cu(I) complexes, [Cu(μ-dppm)(RaaiR/)]2(ClO4)2. The structures of the complexes have been established by spectral (UV-Vis, IR, 1H-NMR) data and the confirmation has been done in case of [Cu(μ-dppm)(HaaiEt)]2(ClO4)2 by single crystal X-ray diffraction studies. Optical stimulation using UV light (365 nm) in methanol solution of the complexes shows that the coordinated RaaiR/ undergoes trans-to-cis isomerization about –N=N-Ar. The rate of trans-to-cis isomerization varies 1.11×10-8 - 1.89×10-8 s-1 and is largely dependent on mass of the photochrome and strain/steric crowding generated about –N=N- bond. Quantum yields (φt→c) of trans-to-cis isomerization, 0.0843 – 0.1421, are calculated and free ligand shows higher φ (0.17 – 0.26) than their complex phase. The cis-to-trans isomerisation is a thermally induced process. The activation energy (Ea) of cis-to-trans isomerisation is calculated by controlled temperature experiment and is found that Ea (ligands) > Ea (complexes).
关键词： photochromism.,Copper (I) complexes,bis-(diphenylphosphino)methane,Arylazoimidazole,spectral study
更新于2025-09-23 15:23:52
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[IEEE 2018 7th International Conference on Agro-geoinformatics (Agro-geoinformatics) - Hangzhou (2018.8.6-2018.8.9)] 2018 7th International Conference on Agro-geoinformatics (Agro-geoinformatics) - Monitoring of Rice Leaf Folder Damage Based on Remote Sensing Methods
摘要： Rice leaf folder (Cnaphalocrocis medinalis Guenée) is one of the most important pests that endanger rice development and yield, which has characteristics of large outbreak areas, high occurrence frequencies and heavy damages. At present, the monitoring methods of rice leaf folder damage is based on artificial investigation, which has the advantages of objective truth and high reliability, while there is a drawback of time-consuming, and it cannot used for a wide range of rice damage monitoring. An ASD (Analytical Spectral Devices, Inc.) Hand-held Spectroradiometer was used at jointing stage of rice. The results showed that, reflectance from rice canopy significantly decreased in the green (530-570 nm) and near infrared (700-1000 nm) regions, and significantly increased in the blue (450-520 nm) and red (580-700 nm) regions as the rice leaf folder population increased. Reflectance from rice canopy significantly decreased in the spectral regions from 737 to 1000 nm as the infestation scale of pest population increased, and the most correlation appeared at 941 nm. The more the numbers of rice leaf folder, the higher the changes of such characteristic parameters. The positive correlations were found between the damage of rice leaf folder and the discrepancy of characteristic parameters in these experimental fields. With China Remote Sensing career advancement, a large number of independent researches and development satellites have launched. Among a new generation of high-resolution satellites, GaoFen-1 (GF-1) stands out. It sets high spatial resolution (2 m-16 m), multi-spectral and high temporal resolution (4-day) with 60 km-800 km swath in a fusion technology with strategic significance. In order to explore the adaptability of Chinese GF-1 images in monitoring rice damage from rice leaf folder, nine rice fields were selected by damage severity in Xinghua City, Jiangsu Province at full heading stage in 2015, and the Ratio Vegetation Index (RVI), Normalized Difference Vegetation Index (NDVI), Enhanced Vegetation Index (EVI), 2-band Enhanced Vegetation Index (EVI2), Soil Adjusted Vegetation Index (SAVI), Optimized Soil Adjusted Vegetation Index (OSAVI) were used to characterize the occurrence of rice leaf folder damages, which were calculated from the satellite GF-1 retrieval data. A series of analyses were performed to disclose the relationship among these six indices and the severity of rice leaf folder. Quantitative correlation analyses showed that NDVI, EVI, EVI2, SAVI, OSAVI and leaf folding population had a highly significant correlation (P<0.01), and SAVI had a highest correlation of 0.94. While there was no significant correlation between RVI and leaf folding population. Therefore, it was feasible to using hyperspectral data and GF-1 satellite images to monitor and warn the outbreak and development of rice leaf folder, which provided a new possible method to monitor dynamically the damage of rice leaf folder.
关键词： pest population,spectral characteristics,rice leaf folder damage,GF-1 WFV image
更新于2025-09-23 15:23:52
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A novel approach for in-situ soot size distribution measurement based on spectrally resolved light scattering
摘要： The present study demonstrates the exploitation of the spectral elastic light scattering technique. Additional information provided by the spectral response of the light scattering signals enables the measurement of the soot size distribution with only two scattering angles. It also provides quantitative data on the spectral dependence of the soot optical index, which is related to the soot chemical composition. The measurement principle consists in dividing the scattered spectra collected at two scattering angles and processing this ratio using the Rayleigh–Debye–Gans theory for Fractal Aggregates (RDG-FA). It is shown that the median diameter of gyration and geometric standard deviation of a lognormal soot size distribution can be determined without any prior information on key parameters such as the fractal prefactor, particle primary diameter, aggregate number density and soot optical properties. A proof of concept was performed on soot particles produced by a miniCAST generator by comparing the optical results with the soot size distributions measured by SMPS. A statistical Bayesian inversion approach was used to determine posterior distributions with a particular emphasis on their uncertainty quantification.
关键词： Light scattering,Bayesian,Spectral scattering,Optical properties,Soot,Size distribution
更新于2025-09-23 15:23:52
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[IEEE 2018 40th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC) - Honolulu, HI (2018.7.18-2018.7.21)] 2018 40th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC) - Remote Heart Rate Measurement from RGB-NIR Video Based on Spatial and Spectral Face Patch Selection
摘要： In this paper, we propose a novel heart rate (HR) estimation method using simultaneously recorded RGB and near-infrared (NIR) face videos. The key idea of our method is to automatically select suitable face patches for HR estimation in both spatial and spectral domains. The spatial and spectral face patch selection enables us to robustly estimate HR under various situations, including scenes under which existing RGB camera-based methods fail to accurately estimate HR. For a challenging scene in low light and with light fluctuations, our method can successfully estimate HR for all 20 subjects (±3 beats per minute), while the RGB camera-based methods succeed only for 25% of the subjects.
关键词： spectral domain,remote sensing,spatial domain,face patch selection,heart rate estimation,RGB-NIR video
更新于2025-09-23 15:23:52
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Contactless parametric characterization of bandgap engineering in p-type FinFETs using spectral photon emission
摘要： In the last decade it has become increasingly popular to use germanium enriched silicon in modern field effect transistors (FET) due to the higher intrinsic mobility of both holes and electrons in SiGe as compared to Si. Whether used in the source/drain region (S/D) as compressive stressor, which is an efficient mobility booster on Si channel devices, or as channel material, the SiGe increases channel carrier mobility and thus enhancing device performance. Because the germanium content modifies the effective bandgap energy EG, this material characteristic is an important technology performance parameter. The bandgap energy can be determined in an LED-like operation of electronic devices, requiring forward biased p-n junctions. P-n junctions in FETs are source or drain to body diodes, usually grounded or reversely biased. This investigation applies a bias to the body that can trigger parasitic forward operation of the source/drain to body p-n junction in any FET. Spectral photon emission (SPE) is used here as a non-destructive method to characterize engineered bandgaps in operative transistor devices, while the device remains fully functional. Before applying the presented technique to a p-type FinFET device, it is put to the proof by verifying the nominal silicon bandgap on an (unstrained) 120 nm technology FET. Subsequently the characterization capability for bandgap engineering is then successfully demonstrated on a SiGe:C heterojunction bipolar transistor (HBT). In a final step, the bandgap energy EG of a 14/16 nm p-type FinFET was determined to be 0.84 eV, which corresponds to a Si0.7Ge0.3 mixture. The presented characterization technique is a contactless fault isolation method that allows for quantitative local investigation of engineered bandgaps in p-type FinFETs.
关键词： p-n junction,Heterojunction bipolar transistor,Bandgap characterization,p-channel FinFET,SiGe, strained Si,Body diode, parasitic operation,Bandgap engineering,Body bias voltage,HBT,Contactless fault isolation,Spectral photon emission,MOSFET
更新于2025-09-23 15:23:52
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single crystals
摘要： 3at.%Tm3+:Ca1?xGdxF2+x (x = 0, 0.005, 0.01, 0.02) single crystals were grown by the vertical Bridgman method, where Gd3+ ions play the role of manipulating ions for local structure to form a disordered lattice site. Spectral properties of these crystals were investigated. Compared to 3at.%Tm3+:CaF2, the spectral parameters of 3at.%Tm3+:Ca1?xGdxF2+x were drastically enhanced in a large scale. LD pumped lasers have been demonstrated in the crystals for the first time. For CW operation, the slope efficiency up to 49.7% was achieved with output power of 1.927 W at 1970 nm. With a birefringent quartz plate, wavelength-tunable laser operation with a tuning range of more than 176 nm was realized.
关键词： Spectral properties,Single crystals,Gd3+ ions,LD pumped lasers
更新于2025-09-23 15:23:52
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[IEEE 2018 IEEE 3rd International Conference on Signal and Image Processing (ICSIP) - Shenzhen, China (2018.7.13-2018.7.15)] 2018 IEEE 3rd International Conference on Signal and Image Processing (ICSIP) - A Two-frequency Subtraction Method to Improve Spectral Peak Identifications
摘要： We discuss a two-frequency subtraction technique to reduce the energy leakage in a Fourier spectrum. In our method, frequency components are determined by finding the periodogram over an interval such that the two frequencies will not interfere with each other. Such a method allows the subtraction of the two main frequency components more accurately from the original signal. The energy leakage from the main components is minimized to allow identification and more accurate determination of weaker components. Statistical error from the subtraction technique can be several times smaller than the FFT method. We show that the subtraction method is relatively robust for signals with varying amplitude or frequency.
关键词： time-frequency analysis,Fourier transform,spectrum estimation,spectral leakage
更新于2025-09-23 15:23:52
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Application of a New Method of Spectral Analysis for Detecting Synchronous Processes in Heliobiology
摘要： Until now, the sum of periodic variations was the main carrier of information in biological and helio-geophysical signals. However, not all of the time series of interest contain dominant periodic components. The relaxation analysis used in this paper makes it possible to generalize the “spectral” formalism to signals that cannot be represented as a sum of a limited number of quasiperiodic components. An algorithm for filtering noise and long-period trends is developed based on the separation of the original signal into rapidly and slowly relaxing components. The main theorem that guarantees the operability of the algorithm is proven. A method for constructing an orthonormal basis whose components have a strictly defined relaxation time is described. The result of the signal expansion over this basis is called the relaxation spectrum. It can be used to divide the time series into signal-to-noise or oscillation-trend if there are no adequate Fourier or stochastic models. The hypothesis that geomagnetic rhythms with periods of about 7 and 9 days have the most significant influence on physiological indicators of biological objects (including those of the population as a whole), as was stated earlier by the heliobiologists, is confirmed based on an automatic algorithm for extracting reliable spectral peaks of population and heliogeomagnetic time series and detecting similar peaks using the S?rensen measure.
关键词： orthonormal basis generation,signal filtering,heliobiophysics,spectral formalism generalization
更新于2025-09-23 15:23:52
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Acquiring spatially varying appearance of printed holographic surfaces
摘要： We present two novel and complimentary approaches to measure diffraction effects in commonly found planar spatially varying holographic surfaces. Such surfaces are increasingly found in various decorative materials such as gift bags, holographic papers, clothing and security holograms, and produce impressive visual effects that have not been previously acquired for realistic rendering. Such holographic surfaces are usually manufactured with one dimensional diffraction gratings that are varying in periodicity and orientation over an entire sample in order to produce a wide range of diffraction effects such as gradients and kinematic (rotational) effects. Our proposed methods estimate these two parameters and allow an accurate reproduction of these effects in real-time. The first method simply uses a point light source to recover both the grating periodicity and orientation in the case of regular and stochastic textures. Under the assumption that the sample is made of the same repeated diffractive tile, good results can be obtained using just one to five photographs on a wide range of samples. The second method is based on polarization imaging and enables an independent high resolution measurement of the grating orientation and relative periodicity at each surface point. The method requires a minimum of four photographs for accurate results, does not assume repetition of an exemplar tile, and can even reveal minor fabrication defects. We present point light source renderings with both approaches that qualitatively match photographs, as well as real-time renderings under complex environmental illumination.
关键词： Diffraction,real-time rendering,spectral,polarization,wave optics
更新于2025-09-23 15:23:52