Search results for "Spectral"
showing 10 items of 3116 documents
Non-regular network performance comparison between HSDPA and LTE
2010
In this paper we study and benchmark the performance of 3rd Generation Partnership Project (3GPP) High Speed Downlink Packet Access (HSDPA) and 3GPP Long Term Evolution (LTE) Downlink with constant bit rate type traffic. In addition a non-regular simulation scenario is considered using realistic propagation data and base station positions related to Tokyo city downtown area. HSDPA was introduced in 3GPP Release 5 and in further releases the technology has been improved with e.g. receive and transmit diversity technologies and support for higher order modulation schemes. LTE was introduced in 3GPP Release 8 with completely new physical layer and improved Radio Resource Management (RRM) funct…
Transverse instability of periodic and generalized solitary waves for a fifth-order KP model
2017
We consider a fifth-order Kadomtsev-Petviashvili equation which arises as a two-dimensional model in the classical water-wave problem. This equation possesses a family of generalized line solitary waves which decay exponentially to periodic waves at infinity. We prove that these solitary waves are transversely spectrally unstable and that this instability is induced by the transverse instability of the periodic tails. We rely upon a detailed spectral analysis of some suitably chosen linear operators.
Conversion of nadir, narrowband reflectance in red and near-infrared channels to hemispherical surface albedo
1997
Abstract Measured nadir-viewed narrow-band reflectanees in red and near infrared channels simulating AVHRR Channels 1 and 2 are compared with measured integrated solar spectrum hemispherical albedos. Reflectanees and albedos were measured from an aircraft over four widely different vegetation surfaces in southeastern Tasmania (Australia). A linear function is used to simultaneously correct for narrow band to broad band conversion errors and to convert nadir viewed reflectances to hemispherical albedos. While the application of the conversion equation presented is limited to the vegetation types of the study, the equation is independent of vegetation type. Results indicate that the reflectan…
ExTTF-Based Dyes Absorbing over the Whole Visible Spectrum
2011
International audience; New push−pull dyes featuring π-extended tetrathiafulvalene (exTTF) as the donor group and tricyanofuran (TCF) as the acceptor group were synthesized and characterized. Their broad absorption covers the entire visible spectral range and enters the near-infrared region. Electrochemistry and theoretical calculations provided an understanding of these singular electronic properties. The new dyes are appealing candidates as light harvesters in photovoltaic devices.
Rotational spectra of gauche perfluoro-n-butane, C4F10; perfluoro-iso-butane, (CF3)3CF; and tris(trifluoromethyl)methane, (CF3)3CH
2007
Abstract The microwave spectra of the gauche conformer of perfluoro- n -butane, n -C 4 F 10 , of perfluoro- iso -butane, (CF 3 ) 3 CF, and of tris(trifluoromethyl)methane, (CF 3 ) 3 CH, have been observed and assigned. The rotational and centrifugal distortion constants for gauche n -C 4 F 10 are: A = 1058.11750(7) MHz, B = 617.6832(1) MHz, C = 552.18794(1) MHz, Δ J = 0.0257(5) kHz, δ J = 0.0052(3) kHz. A C–C–C–C dihedral angle, ω , of ∼55° has been determined. These values agree well with those obtained from a coupled cluster (CCSD/cc-PVTZ) calculation. The rotational and centrifugal distortion constants for iso -C 4 F 10 and iso -C 4 HF 9 are: B o = 816.4519(4) MHz, D J = 0.023(2) …
Singular Neumann (p, q)-equations
2019
We consider a nonlinear parametric Neumann problem driven by the sum of a p-Laplacian and of a q-Laplacian and exhibiting in the reaction the competing effects of a singular term and of a resonant term. Using variational methods together with suitable truncation and comparison techniques, we show that for small values of the parameter the problem has at least two positive smooth solutions.
Turbidez y profundidad de disco de Secchi con Sentinel-2 en embalses con diferente estado trófico en la Comunidad Valenciana
2019
[ES] En los estudios de calidad de aguas por teledetección, uno de los principales indicadores es la transparencia o turbidez del agua. La transparencia puede ser medida in situ mediante la profundidad del disco de Secchi (SD), y la turbidez con un turbidímetro. En las últimas décadas se han utilizado diferentes relaciones entre bandas de diferentes sensores obtenidas por teledetección para la estimación de estos parámetros. En este trabajo, a partir de datos de campo obtenidos a lo largo de 2017 y 2018 en embalses de la cuenca del Júcar con gran variedad de estados tróficos, se han calibrado diferentes índices y bandas para poder estimar la transparencia a partir de imágenes Sentinel-2 (S2…
DeepIndices : Une nouvelle approche des indices de télédétection basée sur l'optimisation et l'approximation de fonctions par DeepLearning. Applicati…
2021
National audience; L'une des avancées les plus importantes dans le domaine de l'observation de la terre est la découverte des indices spectraux, ils ont notamment prouvé leur efficacité dans la caractérisation des surfaces agricoles, mais ils sont généralement définis de manière empirique. Cette étude basée sur l'intelligence artificielle et le traitement du signal, propose une méthode pour trouver un indice optimal. Et porte sur l'analyse d'images issues d'une caméra multi-spectrale, utilisée dans un contexte agricole pour l'acquisition en champ proche de végétation. À partir de six bandes spectrales, cinq modèles ont été testés et déployés dans un framework d'apprentissage profond. Les pe…
A case study of a precision fertilizer application task generation for wheat based on classified hyperspectral data from UAV combined with farm histo…
2013
Different remote sensing methods for detecting variations in agricultural fields have been studied in last two decades. There are already existing systems for planning and applying e.g. nitrogen fertilizers to the cereal crop fields. However, there are disadvantages such as high costs, adaptability, reliability, resolution aspects and final products dissemination. With an unmanned aerial vehicle (UAV) based airborne methods, data collection can be performed cost-efficiently with desired spatial and temporal resolutions, below clouds and under diverse weather conditions. A new Fabry-Perot interferometer based hyperspectral imaging technology implemented in an UAV has been introduced. In this…
Nuclear effects in neutrino-nucleus interactions: the role of spectral functions
2019
En esta tesis hemos estudiado la interacción neutrino-núcleo, en el régimen cuasielástico, haciendo un especial énfasis en la importancia de las correcciones nucleares. Motivación En el estudio de la física de oscilaciones de neutrinos, los desafíos más importantes que se presentan en la actualidad son (i) medir el valor de la fase de la violación de la simetría CP y (ii) discernir entre jerarquía normal o invertida en el respeto de masas de los neutrinos. Los futuros experimentos diseñados para resolver estas (y otras) cuestiones, incluyendo posibles descubrimientos de Física más allá del Modelo Estándar, sobre todo DUNE y T2HK, contarán con una estadística muy alta, asi…