Search results for "Spectral"
showing 10 items of 3116 documents
Optimal Spectral Wavelengths for Discriminating Orchard Species Using Multivariate Statistical Techniques
2019
Sustainable management of orchard fields requires detailed information about the tree types, which is a main component of precision agriculture programs. To this end, hyperspectral imagery can play a major role in orchard tree species mapping. Efficient use of hyperspectral data in combination with field measurements requires the development of optimized band selection strategies to separate tree species. In this study, field spectroscopy (350 to 2500 nm) was performed through scanning 165 spectral leaf samples of dominant orchard tree species (almond, walnut, and grape) in Chaharmahal va Bakhtiyari province, Iran. Two multivariable methods were employed to identify the optimum wavelengths:…
Limiting Carleman weights and conformally transversally anisotropic manifolds
2020
We analyze the structure of the set of limiting Carleman weights in all conformally flat manifolds, 3 3 -manifolds, and 4 4 -manifolds. In particular we give a new proof of the classification of Euclidean limiting Carleman weights, and show that there are only three basic such weights up to the action of the conformal group. In dimension three we show that if the manifold is not conformally flat, there could be one or two limiting Carleman weights. We also characterize the metrics that have more than one limiting Carleman weight. In dimension four we obtain a complete spectrum of examples according to the structure of the Weyl tensor. In particular, we construct unimodular Lie groups whose …
Inverse problems for semilinear elliptic PDE with measurements at a single point
2023
We consider the inverse problem of determining a potential in a semilinear elliptic equation from the knowledge of the Dirichlet-to-Neumann map. For bounded Euclidean domains we prove that the potential is uniquely determined by the Dirichlet-to-Neumann map measured at a single boundary point, or integrated against a fixed measure. This result is valid even when the Dirichlet data is only given on a small subset of the boundary. We also give related uniqueness results on Riemannian manifolds.
The higher order fractional Calderón problem for linear local operators : Uniqueness
2020
We study an inverse problem for the fractional Schr\"odinger equation (FSE) with a local perturbation by a linear partial differential operator (PDO) of order smaller than the order of the fractional Laplacian. We show that one can uniquely recover the coefficients of the PDO from the Dirichlet-to-Neumann (DN) map associated to the perturbed FSE. This is proved for two classes of coefficients: coefficients which belong to certain spaces of Sobolev multipliers and coefficients which belong to fractional Sobolev spaces with bounded derivatives. Our study generalizes recent results for the zeroth and first order perturbations to higher order perturbations.
Spectral multipliers and wave equation for sub-Laplacians: lower regularity bounds of Euclidean type
2018
Let $\mathscr{L}$ be a smooth second-order real differential operator in divergence form on a manifold of dimension $n$. Under a bracket-generating condition, we show that the ranges of validity of spectral multiplier estimates of Mihlin--H\"ormander type and wave propagator estimates of Miyachi--Peral type for $\mathscr{L}$ cannot be wider than the corresponding ranges for the Laplace operator on $\mathbb{R}^n$. The result applies to all sub-Laplacians on Carnot groups and more general sub-Riemannian manifolds, without restrictions on the step. The proof hinges on a Fourier integral representation for the wave propagator associated with $\mathscr{L}$ and nondegeneracy properties of the sub…
Synthesis, NMR spectral and structural studies on mixed ligand complexes of Pd(II) dithiocarbamates: First structural report on palladium(II) dithioc…
2016
Abstract Three new mixed ligand complexes of palladium(II) dithiocarbamates; [Pd(4-dpmpzdtc)(PPh3)(SCN)] (1), [Pd(4-dpmpzdtc)(PPh3)Cl] (2) and [Pd(bzbudtc)(PPh3)Cl] (3), (where, 4-dpmpzdtc = 4-(diphenylmethyl)piperazinecarbodithioato anion, bzbudtc = N-benzyl-N-butyldithiocarbamato anion and PPh3 = triphenylphosphine) have been synthesized from their respective parent dithiocarbamates by ligand exchange reactions and characterized by IR and NMR (1H, 13C and 31P) spectroscopy. IR and NMR spectral data support the isobidentate coordination of the dithiocarbamate ligands in all complexes (1–3) in solid and in solution, respectively. Single crystal diffraction analysis of complexes 1–3 evidence…
A study of Type B uncertainties associated with the photoelectric effect in low-energy Monte Carlo simulations
2021
The goal of this manuscript is to estimate Type B uncertainties in absorbed-dose calculations arising from the different implementations in current state-of-the-art Monte Carlo codes of low-energy photon cross-sections (<200 keV). Monte Carlo simulations are carried out using three codes widely used in the low-energy domain: PENELOPE-2018, EGSnrc, and MCNP. Mass energy-absorption coefficients for water, air, graphite, and their respective ratios; absorbed dose; and photon-fluence spectra are considered. Benchmark simulations using similar cross-sections have been performed. The differences observed between these quantities when different cross-sections are considered are taken to be a go…
Spectrophotometric determination of phthalocyanines Part II. Phthalocyanines stable in concentrated sulfuric acid
2001
Celem pracy było wykazanie możliwości zastosowania spektroskopii VIS do badań ilościowych różnych związków ftalocyjaniny, w szczególności niepodstawionych kompleksów z metalami, które są trwałe w środowisku stężonego kwasu siarkowego(Vl). Zaproponowano prostą metodę, analizy spektrofotometrycznej VIS, stanowiącą kontynuację wcześniej przedstawionej pracy [1], umożliwiając oznaczanie wielu kompleksów ftalocyjaniny z metalami bloku d, Mpc (gdzie M = Cu, Co, Ni, Zn oraz pc (C(32)H(16)N(8)2- = ligand ftalocyjaninowy). Analiza statystyczna wyników uzyskanych w badaniach kontrolnych wykazała, że opisana metoda może być użyteczna zarówno w zastosowaniach przemysłowych jak i badaniach naukowych.
New NEMESIS Results
2021
Funding Information: This work has been supported in part by the EU INTERREG for the Baltic Sea programme within the BSUIN project, and by the Polish Ministry of Science and Higher Education (Grant no. Funding Information: This work has been supported in part by the EU INTERREG for the Baltic Sea programme within the BSUIN project, and by the Polish Ministry of Science and Higher Education (Grant no. 3988/INTERREG BSR/2018/2). Publisher Copyright: © Copyright owned by the author(s) under the terms of the Creative Commons. Preliminary results from a 349-day run (live time) with a 565 kg Pb target and a 166-day background measurement are presented. Three minor anomalies were detected in muon-…
VUV emission spectroscopy combined with H- density measurements in the ion source Prometheus I
2016
“Prometheus I” is a volume H− negative ion source, driven by a network of dipolar electron cyclotron resonance (ECR; 2.45 GHz) modules. The vacuum-ultraviolet (VUV) emission spectrum of low-temperature hydrogen plasmas may be related to molecular and atomic processes involved directly or indirectly in the production of negative ions. In this work, VUV spectroscopy has been performed in the above source, Prometheus I, both in the ECR zones and the bulk (far from ECR zones and surfaces) plasma. The acquired VUV spectra are correlated with the negative ion densities, as measured by means of laser photodetachment, and the possible mechanisms of negative ion production are considered. The well-e…