Letteratura scientifica selezionata sul tema "Termes de Fourier"
Cita una fonte nei formati APA, MLA, Chicago, Harvard e in molti altri stili
Consulta la lista di attuali articoli, libri, tesi, atti di convegni e altre fonti scientifiche attinenti al tema "Termes de Fourier".
Accanto a ogni fonte nell'elenco di riferimenti c'è un pulsante "Aggiungi alla bibliografia". Premilo e genereremo automaticamente la citazione bibliografica dell'opera scelta nello stile citazionale di cui hai bisogno: APA, MLA, Harvard, Chicago, Vancouver ecc.
Puoi anche scaricare il testo completo della pubblicazione scientifica nel formato .pdf e leggere online l'abstract (il sommario) dell'opera se è presente nei metadati.
Articoli di riviste sul tema "Termes de Fourier"
1
Révész, Sz Gy. "Rearrangement of Fourier series and fourier series whose terms have random signs". Acta Mathematica Hungarica 63, n. 4 (dicembre 1994): 395–402. http://dx.doi.org/10.1007/bf01874464.
Testo completo
2
Au-Yeung, Enrico, e John J. Benedetto. "Generalized Fourier Frames in Terms of Balayage". Journal of Fourier Analysis and Applications 21, n. 3 (4 dicembre 2014): 472–508. http://dx.doi.org/10.1007/s00041-014-9369-7.
Testo completo
3
Zozulya, V. V. "A High Order Theory for Linear Thermoelastic Shells: Comparison with Classical Theories". Journal of Engineering 2013 (2013): 1–19. http://dx.doi.org/10.1155/2013/590480.
Testo completoAbstract (sommario):
A high order theory for linear thermoelasticity and heat conductivity of shells has been developed. The proposed theory is based on expansion of the 3-D equations of theory of thermoelasticity and heat conductivity into Fourier series in terms of Legendre polynomials. The first physical quantities that describe thermodynamic state have been expanded into Fourier series in terms of Legendre polynomials with respect to a thickness coordinate. Thereby all equations of elasticity and heat conductivity including generalized Hooke's and Fourier's laws have been transformed to the corresponding equations for coefficients of the polynomial expansion. Then in the same way as in the 3D theories system of differential equations in terms of displacements and boundary conditions for Fourier coefficients has been obtained. First approximation theory is considered in more detail. The obtained equations for the first approximation theory are compared with the corresponding equations for Timoshenko's and Kirchhoff-Love's theories. Special case of plates and cylindrical shell is also considered, and corresponding equations in displacements are presented.
4
Zhang, Zhihua. "Fourier Expansions with Polynomial Terms for Random Processes". Journal of Function Spaces 2015 (2015): 1–12. http://dx.doi.org/10.1155/2015/763075.
Testo completoAbstract (sommario):
Based on calculus of random processes, we present a kind of Fourier expansions with simple polynomial terms via our decomposition method of random processes. Using our method, the expectations and variances of the corresponding coefficients decay fast and partial sum approximations attain the best approximation order. Moreover, since we remove boundary effect in our decomposition of random process, these coefficients can discover the instinct frequency information of this random process. Therefore, our method has an obvious advantage over traditional Fourier expansion. These results are also new for deterministic functions.
5
Hasanah, Dahliatul. "On continuity properties of the improved conformable fractional derivatives". Jurnal Fourier 11, n. 2 (31 ottobre 2022): 88–96. http://dx.doi.org/10.14421/fourier.2022.112.88-96.
Testo completoAbstract (sommario):
The conformable fractional derivative has been introduced to extend the familiar limit definition of the classical derivative. Despite having many advantages compared to other fractional derivatives such as satisfying nice properties as classical derivative and easy to solve numerically, it also has disadvantages as it gives large error compared to Riemann-Liouville and Caputo fractional derivatives. Modified types of conformable derivatives have been proposed to overcome the shortcoming. The improved conformal fractional derivatives are declared to be better approximations of Riemann-Liouville and Caputo derivatives in terms of physical behavior. In this paper, properties concerning continuity of the improved conformable fractional derivative are investigated. We prove the relation between -differentiable and continuity of a function and corresponding interior extremum theorem. We also prove the properties close to Rolle’s Theorem and Mean Value Theorem for the improved conformable fractional derivatives.
6
Dukhnovsky, Sergey Anatolievich. "Secular Terms for the Kinetic Mckean Model". Differential Equations and Control Processes, n. 1 (2023): 125–36. http://dx.doi.org/10.21638/11701/spbu35.2023.108.
Testo completoAbstract (sommario):
In this article, we investigate the kinetic McKean model. The perturbed solution of the Cauchy problem is sought in the form of Fourier series. The Fourier coefficients for the zero and nonzero modes are written out, respectively. The original system is reduced to an infinite system of differential equations. An approximation for the systems is constructed. Under certain assumptions, we find secular terms (non-integrable part). This, in turn, will allow us to prove for the first time the exponential stabilization of the solution in the future.
7
Nunes de Oliveira, João Francisco, Roberta Veloso Garcia, Hélio Koiti Kuga e Estaner Claro Romão. "Efficiency of Solution Methods for Kepler’s Equation". Applied Mechanics and Materials 851 (agosto 2016): 587–92. http://dx.doi.org/10.4028/www.scientific.net/amm.851.587.
Testo completoAbstract (sommario):
This article discusses, in the case of eccentric orbits, some solution methods for Kepler's equation, for instance: Newton's method, Halley method and the solution by Fourire-Bessel expansion. The efficiency of solution methods is evaluated according to the number of iterations that each method needs to lead to a solution within the specified tolerance. The solution using Fourier-Bessel series is not an iterative method, however, it was analyzed the number of terms required to achieve the accuracy of the prescribed solution.
8
Lü, Baida, Fanlong Kong e Bin Zhang. "Optical systems expressed in terms of fractional Fourier transforms". Optics Communications 137, n. 1-3 (aprile 1997): 13–16. http://dx.doi.org/10.1016/s0030-4018(96)00775-4.
Testo completo
9
Getsadze, Rostom. "Divergence of Spherical General Terms of Double Fourier Series". Journal of Fourier Analysis and Applications 12, n. 5 (ottobre 2006): 597–604. http://dx.doi.org/10.1007/s00041-006-6045-6.
Testo completo
10
Angelika, Venthy, e Joko Harianto. "Analisis Sensitivitas Model SEIV pada Kasus Penularan Penyakit Polio". Jurnal Fourier 12, n. 2 (31 ottobre 2023): 60–68. http://dx.doi.org/10.14421/fourier.2023.122.60-68.
Testo completoAbstract (sommario):
The trend of polio transmission cases until 2023 is still fluctuating and does not tend to decrease monotonically. This incident is important to discuss, especially about the factors that influence cases of polio transmission. One of the studies used to describe the incidence of polio transmission is through mathematical model analysis. One of the mathematical models used to represent the incidence of polio transmission is a dynamic model with the Susceptible-Exposed-Infected-Vaccinated (SEIV) compartment. The SEIV model analyzed in this study involves seven parameters. If the value of each parameter fluctuates, it will affect cases of polio transmission. Therefore, this research aims to analyze the influence of each parameter in the SEIV model on cases of polio transmission. The method used in this research is the literature study method. Secondary data in this study was used to create a SEIV model simulation. The findings of this research are that two parameters have the greatest influence on cases of polio transmission. The infection transmission rate parameter is the most influential parameter in terms of increasing cases of polio transmission because the sensitivity index value is the highest among the other six parameters. Meanwhile, the natural death rate parameter is the parameter that has the most influence on reducing cases of polio transmission. This is because based on the sensitivity index value, the death rate parameter has the lowest sensitivity index value among the other six parameters.
Tesi sul tema "Termes de Fourier"
1
Han, Cundi. "Numerical method for non-integer order PDE : approximations and parameter identification". Electronic Thesis or Diss., Bourges, INSA Centre Val de Loire, 2024. http://www.theses.fr/2024ISAB0004.
Testo completoAbstract (sommario):
L'objectif principal de cette thèse est de proposer une méthode numérique basée sur les polynômes de Bernstein et des termes de sinusoidaux. Cette méthode est utilisée pour traiter numériquement les modèles structurels linéaires et non linéaires avec dérivée d'ordre fractionnaire. Comparé à l'ordre entier, l'ordre fractionnaire offre une meilleure mémoire temporelle et permet d'utiliser moins de paramètres pour simuler plus précisément le comportement dynamique du modèle. Cependant, il est très difficile d'obtenir la solution analytique du modèle structurel en raison de l'existence de l'ordre fractionnaire. Pour relever ce défi, nous construisons une matrice associée aux équations gouvernant le modèle structurel en nous basant sur les polynômes de Bernstein et les termes de Fourier. La méthode des moindres carrés par variables discrètes est ensuite appliquée pour obtenir des solutions approximatives au système d'équations linéaires. Certains modèles structurels complexes d'ordre fractionnaire sont régis par des équations différentielles partielles fractionnaires multidimensionnelles. Par conséquent, nous étendons la méthode proposée dans cette thèse d'une approximation de fonction inconnue unidimensionnelle à une fonction inconnue multidimensionnelle. Cela permet à la méthode numérique de mieux capturer et analyser les caractéristiques dynamiques du modèle structurel. Les équations différentielles partielles non linéaires sont omniprésentes dans de nombreux modèles structurels d'ordre fractionnaire. L'existence de termes non linéaires introduit plus d'interactions et de dépendances entre les variables, ce qui augmente la difficulté du calcul. Par conséquent, cette thèse traite également efficacement les termes non linéaires du modèle fractionnaire multidimensionnel et de manière itérative. De plus, nous avons non seulement calculé des solutions approximatives pour différents modèles, mais nous avons également identifié efficacement des paramètres pour les modèles d'ordre fractionnaire. Grâce à différents exemples numériques d'ordre fractionnaire et à la comparaison avec d'autres méthodes, l'efficacité, l'applicabilité et la précision de la méthode proposée dans cette thèse sont vérifiéesThe main purpose of this thesis is to propose a novel and accurate numerical method based on Bernstein polynomials and Fourier terms. This method is used for the numerically process of fractional order linear and nonlinear structural models. Compared with the integer order, the fractional order has better time memory and can use fewer parameters to simulate the dynamic behavior of the model more accurately. However, it is very difficult to obtain the analytical solution of the structural model due to the existence of fractional order. To address this challenge, we derive the operator matrix associated with the structural model governing equations based on Bernstein polynomials and Fourier term function approximations. The fractional order partial differential governing equations are transformed into the form of an operator matrix. The least squares method by discrete variables is further applied to obtain approximate solutions to the system of linear equations. Some complex fractional order structural models are governed by multi-dimensional fractional partial differential equations. Therefore, we extend the method proposed in this thesis from a one-dimensional unknown function approximation to multi-dimensional unknown function. This allows the numerical method to better capture and analyze the dynamic characteristics of the structural model. Nonlinear partial differential governing equations are ubiquitous in many fractional order structural models. The existence of nonlinear terms introduces more interactions and dependencies between variables which increases the difficulty of calculation. Therefore, this thesis also effectively handles the nonlinear terms of the multi-dimensional fractional order model and corrects the errors. In addition, we not only calculated approximate solutions for different models but also effectively identified parameters for fractional order models. Through different fractional order numerical examples and comparison with other methods, the effectiveness, applicability and accuracy of the method proposed in this thesis are verified
2
Ichalalene, Zahia. "Étude par spectroscopies Fourier et Raman du matériau laser YVO[4] dopé au néodyme". Sherbrooke : Université de Sherbrooke, 2000.
Cerca il testo completo
3
Li, Zhenghong. "The role of the counter rotating terms in spontaneous emission and the time evolution of lamb shift". HKBU Institutional Repository, 2012. https://repository.hkbu.edu.hk/etd_ra/1419.
Testo completo
4
Ferreira, Ana Carolina dos Santos. "Previsão de séries temporais com períodos sazonais complexos : uma aplicação empírica". Master's thesis, Instituto Superior de Economia e Gestão, 2018. http://hdl.handle.net/10400.5/17494.
Testo completoAbstract (sommario):
Mestrado em Econometria Aplicada e PrevisãoO call center é, hoje em dia, um dos fatores estratégicos para o crescimento de uma empresa. Sendo a satisfação do cliente uma prioridade e o call center um dos primeiros pontos de contacto com o mesmo, garantir um bom serviço poderá melhorar a relação e gerar oportunidades de crescimento. Cada contacto com o cliente traz mais conhecimento e este conhecimento é precioso para gerar aproximação e comunicação mais assertiva. Conhecer as suas características e os motivos que o fazem ligar são pontos-chave para antecipar as suas necessidades. Assim, um call center bem estruturado e preparado para atender de forma rápida mostra eficiência e preocupação da empresa. A aplicação empírica mostra análises capazes de traçar o perfil do cliente ao nível sociodemográfico e ao nível de segmentações do negócio. Mostra também a interpretação de todas as interações entre motivos de chamada, capazes de criar inputs para a tomada de decisão ao nível operacional. Corrobora-se a presença de padrões sazonais através da análise espectral, que foi tida em conta na modelação da série. Conclui-se que o melhor método de previsão é o ARIMA cujo padrão sazonal é explicado por termos de uma série de Fourier.
Call center are nowadays one of the strategic factors for the growth of a company. As customer satisfaction is priority, and since call centers are one of the first contact points with a company's clients, ensuring a good service can improve customer-relationship and generate growth opportunities. Each contact with a client brings additional knowledge, and that knowledge is precious to generate proximity and increase communication assertivity. Knowing their characteristics and the motivations behind their call are key factors in the anticipation of their needs. Thus, a well-structured call center which is ready for quick call handling shows efficiency and concern from the company. The empirical application introduces analytical methods capable of tracing the client profile at the socio-demographic level and at the business segmentation level. It also presents the interpretations of all interactions between call reasons capable of creating inputs for decision-making at the operational level. Spectral analysis validates the presence of seasonal patterns, which we controlled for when modelling the series. It is concluded that the best prediction method is the ARIMA model whose seasonal pattern is explained by terms of a Fourier series.
info:eu-repo/semantics/publishedVersion
5
Mercat, Benjamin. "Analyse temps-fréquence en mécanique cellulaire et adaptabilité du fuseau mitotique". Thesis, Rennes 1, 2016. http://www.theses.fr/2016REN1S124/document.
Testo completoAbstract (sommario):
Le fuseau mitotique assure la ségrégation des chromatides sœurs et le maintien de la poïdie des cellules filles. Le fuseau est composé de microtubules dynamiques (qui polymérisent et dépolymérisent continuellement), de nombreux moteurs moléculaires, d'agents de réticulations et de régulateurs. Bien que la structure du fuseau au niveau moléculaire soit connue, son fonctionnement reste délicat à comprendre, et nécessite la prise en compte de la dynamique de ses composants et leurs interactions. Les approches utilisées pour répondre à ces problématiques sont jusqu'à maintenant plutôt des approches in silico et in vitro. Il manque aujourd'hui une caractérisation de la mécanique du fuseau dans son contexte physiologique. Nous proposons une méthode non invasive basée sur de l'analyse d'image, combiné à une modélisation heuristique pour mesurer les paramètres mécaniques durant toute la division. Nous suivons les pôles du fuseau marqués par protéine fluorescente avec un taux acquisition rapide et une bonne résolution spatiale ce qui nous permet d'accéder aux fluctuations de longueur du fuseau in vivo. Avec la transformée de Fourier aux temps courts, nous calculons leurs densités spectrales de puissances — leurs signatures mécaniques. Ces spectres sont alors ajustés avec un modèle Kelvin — Voigt avec inertie (un ressort, un amortisseur et un terme inertiel en parallèle). Nous avons validé la méthode par des expériences numériques où nous retrouvons les évolutions des paramètres sur des données simulées et la calibration a été réalisée par l'utilisation de la rupture du fuseau induite par micro chirurgie laser ou par la génétique. Nous avons caractérisé le fuseau de l'embryon unicellulaire du nématode C. elegans. La méthaphase apparaît dominée par l'amortisseur, ce qui est cohérent avec la lente élongation du fuseau que nous observons. Mais contraste l'idée répandue de l'existence d'un mécanisme de maintien de la longueur du fuseau durant la métaphase. Au passage en anaphase, les trois paramètres mécaniques chutent, avant de réaugmenter environ 50 secondes après la transition pour réatindre un régime dominé de nouveau par l'amortisseur, ce qui suggère que les microtubules interpolaires jouent un rôle mineur durant l'élongation du fuseau en début d'anaphase. Dans la perspective de comprendre le lien entre la mécanique du fuseau et les interactions des acteurs moléculaires, nous avons partiellement supprimé un gène par sous-structure du fuseau. Nous avons alors retrouvé des comportements connus avec une perspective augmentée offerte par notre méthode. Cette méthode, ne va pas seulement permettre la compréhension fondamentale de la mécanique du fuseau, en remplaçant la modélisation du fuseau basé uniquement sur la longueur, mais aussi d'aller vers la prise en compte de la robustesse de fonctionnement du fuseau mitotique face aux défauts tel que la polyou l'aneuploïdieThe mitotic spindle ensures the correct segregation of the sister chromatids to maintain ploidy in daughter cells. The spindle comprises dynamical microtubules (alternating polymerizing and depolymerizing), a variety of molecular motors, crosslinker and the regulators. Although the molecular grounds of spindle structure is well known, the link to its functions remain elusive, calling for including the dynamics of its components and their interactions. These questions were mostly investigated by in silico or in vitro approaches. But a detailed characterizing of spindle mechanics, in physiological conditions, is missing. We propose an image processing based, non invasive, method combined to an heuristic model to measure mechanical parameters of the mitotic spindle along time. We tracked fluorescently labeled spindle pole at high temporal and spatial resolution and measured the variations of spindle length, in vivo. We computed their power density spectrum using short time Fourier transform (sliding window) — a blueprint of spindle mechanics. Such a spectrum is then fitted with a Kelvin —Voigt model with inertia (a spring, a damper, an inertial element in parallel). We validated this method by recovering the mechanical parameters over time from simulated data and calibrated it uses laser and genetically induced spinlde cut. We characterized the mitotic spindle of the one-cell embryo of nematode C. elegans. Metaphase appeared dominated by damping element, consistent with the slow spindle elongation observed. But in contrast with the common thought that a mechanism maintains the spindle length during metaphase. At anaphase onset, all three parameters collapsed, before increasing about 50s later to reach a regime where damping dominated again, suggesting the overlapping spinlde microtubules may play a minor role in early anaphase spinlde elongation. In perspective of understanding how spindle mechanics emerge of molecular players interactions, we depleted one gene per splindle sub-structure — overlapped microtubules, kinetochore microtubules, central spindle and astral microtubules. We succefully recovered some known behavior but with the augmented insight offered by our method. This method paves the way not only towards understanding the fundamentals of spindle mechanics, superseding the degenerated modeling based on the sole spindle length but also towards acounting for spindle functional robustness towards defect as polyor aneuploidy
6
Taleb, Samir. "Génération de symptômes flous par FFT et SWT : applications à la détection de vibrations". Phd thesis, Grenoble INPG, 2007. http://www.theses.fr/2007INPG0022.
Testo completoAbstract (sommario):
L'objectif de ce travail est la détection des défauts à travers la détection des changements dans les signaux mesurés. Notre travail présente une méthode permettant de construire, à partir d'historique de données, un modèle comportemental du procédé, puis de détecter des situations anormales issues des dysfonctionnements. Cette méthode consiste à générer des symptômes flous en ligne permettant de suivre l'évolution temporelle du fonctionnement du système à surveiller. Ces symptômes prennent en considération les incertitudes sur la décision en fusionnant le résultat du test de détection avec celui de sa validité. Les propriétés de la STFT et la SWT permettent d'extraire des informations des signaux analysés. Un symptôme graduel est obtenu en fonction du type et de l'ampleur du défaut. La méthode de détection a été testée sur des signaux contenant des défauts simulés, puis validée sur des données industrielles pour la détection des vibrations torsionnelles dans un laminoir réversibleThe purpose of this work is fault detection through changes detection in the measured signals. Our work presents a method making possible to build a behavioral model of the process, using historical process data, in order to detect abnormal situations resulting from dysfunctions. This method consists in generating on line progressive symptoms, making possible to follow the temporal evolution of the system operation to be supervised. These symptoms take into account uncertainties on the decision by aggregating the result of the detection test with that of its validity. STFT and SWT properties allow this method to extract relevant information from the analyzed signals. A gradual symptom is obtained according to the type and from of the extent fault. The fault detection method conceived was initially tested on signals containing simulated faults was then validate on industrial signals to detect the torsional vibrations in a reversing rolling mill
7
Daucé, Rachel. "Effets de l'irradiation sur les verres d'aluminosilicates de terres rares de type SiAlO(N) dans le contexte de la transmutation des actinides". Rennes 1, 2003. http://www.theses.fr/2003REN10100.
Testo completoAbstract (sommario):
La transmutation des actinides permettrait de diminuer le volume de déchets nucléaires susceptibles d'être enfouis en couches géologiques profondes. Toutefois, une matrice est généralement nécessaireautour des radioéléments après leur séparation poussée. Si l'irradiation dans le contexte de la transmutation de matériaux références cristallisés a été largement étudiée, aucune étude n'a porté surles amorphes dans de telles conditions. L'étude de l'évolution des verres sous bombardement d'ionslourds peut toutefois permettre de mieux comprendre les mécanismes d'endommagement mis en jeu lors de l'irradiation. Les verres étudiés, de type SiAlO(N), ont été choisis pour leur réfractarité, leur durabilité chimique prouvée et leurs excellentes propriétés mécaniques. Cinq compositions, dans les systèmes Y-Mg-Si- Al-O(-N), Nd-Mg-Si-Al-O(-N) et La-Y-Si-Al-O-N, ont été synthétisées et caractérisées. Irradiés au GANIL (Caen) par des ions lourds d'une énergie de plusieurs centaines de MeV, ces verres voient leur dureté décroître suite à l'irradiation. Ce phénomène, fortement lié au pouvoir d'arrêt électronique de l'ion incident, semble indépendant de la quantité et de la nature des modificateurs du réseau. La diminution de la dureté est cependant plus marquée dans le cas des verres contenant de l'azote. Elle est liée à un changement dans le mécanisme de déformation du verre : de comportement ± normal α avant irradiation, ce dernier se déforme par densification suite au bombardement. Ce changement dans la réponse à l'indentation est probablement dû à plusieurs modifications structurales. En effet, l'absorption UV-visible met en évidence la présence d'un nombre accru de défauts ponctuels après bombardement. De plus, particulièrement dans le cas des verres contenant de l'azote, l'environnement local du silicium et de l'aluminium, étudiés en spectroscopie RMN et Raman,sont largement perturbés par l'irradiation.
8
Pereira, Thieres Magaive Costa. "Aplicações da Espectrometria de Massas de Ressonância Ciclotrônica de Íons por Transformada de Fourier (FT-ICR MS) em Petroleômica". Universidade Federal do Espírito Santo, 2013. http://repositorio.ufes.br/handle/10/6748.
Testo completoAbstract (sommario):
Made available in DSpace on 2016-12-23T14:41:52Z (GMT). No. of bitstreams: 1
Thieres Magaive Costa Pereira.pdf: 7173330 bytes, checksum: 5a2aee56b5048351ab0fc838877f8030 (MD5)
Previous issue date: 2013-08-23O petróleo é uma mistura complexa, sendo uma das misturas mais desafiadoras para as análises químicas. Muitas técnicas são empregadas para a caracterização dos constituintes do óleo. Entretanto, quando combinamos o altíssimo poder de resolução e exatidão da espectrometria de massas, em especial a Ressonância Ciclotrônica de Íons com Transformada de Fourier, (FT-ICR MS) com fontes de ionização a pressão atmosférica, uma atribuição precisa de mais de 20 000 compostos orgânicos do petróleo pode ser obtida. Na indústria do petróleo existe um grande interesse na análise de ácidos naftênicos e asfaltenos devido a problemas como corrosão e formação de depósitos, que aumentam os custos de produção. Portanto este trabalho tem como objetivo a avaliação da termodegradação de ácidos naftênicos, além do emprego das fontes de ESI, APCI, APPI, LDI e MALDI para aquisição de novos dados relativos a caracterização de asfaltenos. Dois petróleos foram utilizados nos ensaios de termodegradação, o petróleo A com acidez de 2,38 mg KOH g-1 e o petróleo B com 4,79 mg KOH g-1 os quais foram tratados a 280, 300 e 350 ºC pelo período de 2, 4 e 6 horas. De uma maneira geral, as principais classes identificadas para ambas às amostras foram O2, N e NO2, respectivamente. Uma leve redução do NAT e da abundância relativa referente à classe O2 foram observado em função da temperatura e do tempo de envelhecimento (T = 280 → 300 oC e t = 2 → 6 h), sendo que a temperatura de tratamento térmico a 350 ºC demonstrou-se determinante na remoção de compostos da classe O2. O perfil químico de amostras de asfaltenos brasileiros foi avaliado utilizando-se cinco diferentes métodos de ionização em ambos os modos de ionização: positivo e negativo, depois, a distribuição de peso molecular, distribuição de classe, parcelas típicas de número de carbono contra DBE e diagramas van Krevelen foram obtidos e discutidos. Um comportamento atípico foi observado para a fonte de LDI e MALDI (±) FT-ICR MS. Um amplo perfil, de m/z 500-3000, apresentando espaçamento de 24 Da foi observado, e este corresponde a formas alotrópicas de fulereno, C60. Em geral, os asfaltenos apresentaram um elevada proporção de espécies heteroatómicas como: HC, HC [H], N, N [H], N2O, N2O [H], N2, N2 [H], O, O[H] para o modo (+) e N, N [H], NO, NO [H], NO, NO2[H], N2O, N2O[H] para o modo negativo. Nos diagramas de DBE contra o número de carbono, os asfaltenos mostraram para cada valor de DBE uma pequena amplitude de compostos com respeito à NC, proporcionando assim, imagens que formam uma linha de 45 ° entre os eixos CN e DBE. Isto indica que estes compostos não exibem grandes cadeias de alquílicas, sendo composta principalmente por anéis aromáticos. Em geral os diagramas de van Krevelen mostraram alta proporção de compostos com razão H/C ~0,7, corroborando com a existência de espécies altamente aromáticas
Petroleum is a complex mixture, being one of the most challenging mixtures for chemical analyzes. Many techniques are employed to characterize constituents of the oil. However , when we combine the highest resolving power and accuracy of mass spectrometry , especially Ion Cyclotron Resonance Fourier Transform ( FT - ICR MS ) with sources of atmospheric pressure ionization , an assignment need more than 20 000 organic compounds in the oil can be obtained. In the oil industry there is a great interest in the analysis of asphaltenes and naphthenic acids due to problems such as corrosion and deposit formation, which increases production costs. Therefore this study aims to evaluate the thermodegradation of naphthenic acids, besides the use of sources of ESI, APCI, APPI, MALDI and LDI for the acquisition of new data on the characterization of asphaltenes . Two test oils were used in thermodegradation of the oil with an acidity of 2.38 mg KOH g -1 and Oil B with 4.79 mg KOH g- 1 which were treated at 280 , 300 and 350 ° C for a period of 2 , 4 and 6 hours. Generally, the major classes identified for both samples O2, NO2, and C, respectively. A slight reduction of NAT and relative abundance refers to the class O2 were observed as a function of temperature and aging time (T = 280 → 300 ° C t = 2 → 6 h), and the heat treatment temperature at 350 ° C showed a determinant for the removal of class O2. The chemical asphaltenes Brazilian samples was evaluated using five different methods of ionization in both modes of ionization: positive and negative, then the molecular weight distribution, distribution class, typical plots versus carbon number and DBE van Krevelen diagrams were obtained and discussed. An unusual behavior was observed for the LDI and MALDI source ( ± ) FT - ICR MS . A comprehensive profile of m / z 500-3000, with spacing of 24 Da was observed, and this corresponds to allotropes of fullerene C60. In general, the asphaltenes had an heteroatómicas high proportion of species such as HC , HC [ H] , N, [ H] , N2O N2O [ H] N2, N2 [ M ] O O [ H] to mode (+) and N, [ H ] , NO [ H] , NO , NO2, [ H] , N2O N2O [ H ] for the negative mode . In the diagrams DBE against the carbon number , the asphaltenes shown for each value of DBE composed of a small amplitude with respect to NC, thus providing images that form a line of 45 ° between the axes CN and DBE. This indicates that these compounds do not exhibit large chain alkyl, composed mainly of aromatic rings. In general diagrams van Krevelen showed a high proportion of compounds ratio H / C ~ 0.7, confirming the existence of highly aromatic species
9
Taleb, Samir. "Génération de symptômes flous par FFT et SWT : applications à la détection de vibrations". Phd thesis, Grenoble INPG, 2007. http://tel.archives-ouvertes.fr/tel-00239310.
Testo completoAbstract (sommario):
L'objectif de ce travail est la détection des défauts à travers la détection des changements ou des anomalies dans les signaux mesurés. Notre travail présente une méthode permettant de construire, à partir d'historique de données (signaux de référence), un modèle comportemental du procédé, puis de détecter des situations anormales issues des dysfonctionnements. Cette méthode consiste à générer des symptômes flous en ligne permettant de suivre l'évolution temporelle du fonctionnement du système à surveiller. Ces symptômes prennent en considération les incertitudes sur la décision en fusionnant le résultat du test de détection avec celui de sa validité. Par leurs propriétés de localisation fréquentielle et temps-fréquence, la transformée de Fourier à court terme et la transformée en ondelettes stationnaires sont deux méthodes adaptables au diagnostic. Les choix de la longueur et du type de la fenêtre de pondération pour la STFT, de l'ondelette mère et du nombre de niveaux de décomposition pour la SWT sont les degrés de liberté qui leur permettent d'extraire des informations pertinentes des signaux analysés. Un symptôme graduel est obtenu en fonction du type et de l'ampleur du défaut. La méthode de détection conçue a été testée sur des signaux contenant des défauts simulés, puis a été ensuite validée sur des données industrielles pour la détection des vibrations torsionnelles dans un laminoir réversible (laminage à chaud). Les degrés de liberté de la méthode proposée confèrent aux méthodes développées la flexibilité par rapport à différentes applications.
10
Zongo, Sylvie Brizard. "Fluctuations multi-échelles et extrêmes dans les séries temporelles biogéochimiques à moyen et long terme en milieu marin côtier". Thesis, Lille 1, 2010. http://www.theses.fr/2010LIL10135/document.
Testo completoAbstract (sommario):
Cette thèse porte sur l’étude de séries temporelles biogéochimiques à moyen et long terme, de façon à caractériser leurs fluctuations à de multiples échelles, et en particulier leurs extrêmes. Les données a proviennent en grande partie des programmes MAREL et SOMLIT. Le programme MAREL a été mis en œuvre par l’Ifremer et basé sur des mesures à haute fréquence. Le programme SOMLIT est un service d’observation labellisé depuis 1997 par l’INSU. Ces mesures sont effectuées tous les 15 jours, par prélèvement, en un point fixe dans les eaux côtières en Manche. Pour l’analyse de ces séries temporelles, les méthodes utilisées sont empruntées aux domaines de l’analyse numérique et de la turbulence. Cette étude est effectuée en 3 parties. Dans la première partie, l’analyse du spectre de Fourier a permis de mesurer l’influence du forçage physique sur la distribution des paramètres à haute fréquence. Dans la seconde partie, la comparaison entre des données SOMLIT et MAREL recueillies en des endroits très proches à Boulogne-sur-mer a pu montrer une complémentarité mais tout en mettant en évidence le caractère plus informatif du système MAREL. La comparaison entre deux sites distincts en Manche (orientale et occidentale) a permis de déceler les similitudes et les différences dans les teneurs des ratios (N/P/Si ;COP/Chla). Dans la troisième partie, on a pu mettre en évidence l’influence des événements extrêmes du débit de la Seine sur la distribution de certains paramètres biogéochimiques mesurés à Honfleur. Nous avons également mis en évidence dans le cadre de la DCE, l’influence de l’échelle d’étude sur les estimations de certaines métriques nécessaires à la définition du bon état écologique à partir des données issues de la haute fréquenceThis thesis focuses on the study of biogeochemical time series in order to characterize the dynamics of their fluctuations on a wide range of scales, and in particular their extremes. The databases analyzed here are mainly provided by the MAREL and SOMLIT programmes. The MAREL program is a network of automatic measuring devices monitoring coastal marine environments implemented by Ifremer. The SOMLIT is a French national program operated by INSU. The measurements are made once every two weeks on the fixed stations. In order to analyze these time series, methods have been borrowed from the fields of numerical analysis and turbulence. The study was conducted in three parts. In the first part, we consider the high frequency time series. The Fourier spectral analysis reveals the influence of physical forcing on the distribution of the parameters. The second part of the study compares SOMLIT and MAREL results recorded from sites near Boulogne-sur-mer. The comparison of the two measuring systems (manual and automatic) showed that while they are complementary, the automatic MAREL system is more informative. The probability density functions (pdfs) of some ratios reveal extreme values in their dynamics. These pdfs reveal in all cases a hyperbolic behavior in the tail probability of the ratios. In the third part, we consider the influence of extremes events of the Seine flow on the distribution of some biogeochemical parameters. This section is also concerned with the analysis of data at high frequency in order to estimate of water masses state in the English Channel within the context of the Water Framework Directive (WFD)
Libri sul tema "Termes de Fourier"
1
Terres promises: Émerveillement et récit au XXe siècle : Alain-Fournier, Breton, Dhôtel, Gracq, Germain. [Paris]: J. Corti, 2011.
Cerca il testo completo
2
Horing, Norman J. Morgenstern. Thermodynamic Green’s Functions and Spectral Structure. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198791942.003.0007.
Testo completoAbstract (sommario):
Multiparticle thermodynamic Green’s functions, defined in terms of grand canonical ensemble averages of time-ordered products of creation and annihilation operators, are interpreted as tracing the amplitude for time-developing correlated interacting particle motions taking place in the background of a thermal ensemble. Under equilibrium conditions, time-translational invariance permits the one-particle thermal Green’s function to be represented in terms of a single frequency, leading to a Lehmann spectral representation whose frequency poles describe the energy spectrum. This Green’s function has finite values for both t>t′ and t<t′ (unlike retarded Green’s functions), and the two parts G1> and G1< (respectively) obey a simple proportionality relation that facilitates the introduction of a spectral weight function: It is also interpreted in terms of a periodicity/antiperiodicity property of a modified Green’s function in imaginary time capable of a Fourier series representation with imaginary (Matsubara) frequencies. The analytic continuation from imaginary time to real time is discussed, as are related commutator/anticommutator functions, also retarded/advanced Green’s functions, and the spectral weight sum rule is derived. Statistical thermodynamic information is shown to be embedded in physical features of the one- and two-particle thermodynamic Green’s functions.
Capitoli di libri sul tema "Termes de Fourier"
1
Segrest, John F., Joseph J. F. Liu e Victor G. Szebehely. "Fourier Transform in Astrodynamics". In Long-Term Dynamical Behaviour of Natural and Artificial N-Body Systems, 477–79. Dordrecht: Springer Netherlands, 1988. http://dx.doi.org/10.1007/978-94-009-3053-7_44.
Testo completo
2
Uchiyama, Akihito. "Characterization of H 1 in terms of Fourier multipliers". In Springer Monographs in Mathematics, 241–51. Tokyo: Springer Japan, 2001. http://dx.doi.org/10.1007/978-4-431-67905-9_26.
Testo completo
3
Uchiyama, Akihito. "Characterization of H p in terms of Fourier multipliers". In Springer Monographs in Mathematics, 281–84. Tokyo: Springer Japan, 2001. http://dx.doi.org/10.1007/978-4-431-67905-9_28.
Testo completo
4
Sanyal, Swagato. "Near-Optimal Upper Bound on Fourier Dimension of Boolean Functions in Terms of Fourier Sparsity". In Automata, Languages, and Programming, 1035–45. Berlin, Heidelberg: Springer Berlin Heidelberg, 2015. http://dx.doi.org/10.1007/978-3-662-47672-7_84.
Testo completo
5
Uchiyama, Akihito. "Preliminaries for characterizations of H p in terms of Fourier multipliers". In Springer Monographs in Mathematics, 167–72. Tokyo: Springer Japan, 2001. http://dx.doi.org/10.1007/978-4-431-67905-9_17.
Testo completo
6
Pascalau, Razvan, Christian Thomann e Greg N. Gregoriou. "Unconditional Mean, Volatility, and the FOURIER-GARCH Representation". In Financial Econometrics Modeling: Derivatives Pricing, Hedge Funds and Term Structure Models, 90–106. London: Palgrave Macmillan UK, 2011. http://dx.doi.org/10.1057/9780230295209_5.
Testo completo
7
Uchiyama, Akihito. "Other results on the characterization of H p in terms of Fourier multipliers". In Springer Monographs in Mathematics, 177–82. Tokyo: Springer Japan, 2001. http://dx.doi.org/10.1007/978-4-431-67905-9_19.
Testo completo
8
Lobbe, Alexander, Dan Crisan, Darryl Holm, Etienne Mémin, Oana Lang e Bertrand Chapron. "Comparison of Stochastic Parametrization Schemes Using Data Assimilation on Triad Models". In Mathematics of Planet Earth, 159–91. Cham: Springer Nature Switzerland, 2023. http://dx.doi.org/10.1007/978-3-031-40094-0_7.
Testo completoAbstract (sommario):
AbstractIn recent years, stochastic parametrizations have been ubiquitous in modelling uncertainty in fluid dynamics models. One source of model uncertainty comes from the coarse graining of the fine-scale data and is in common usage in computational simulations at coarser scales. In this paper, we look at two such stochastic parametrizations: the Stochastic Advection by Lie Transport (SALT) parametrization introduced by Holm (Proc A 471(2176):20140963, 19, 2015) and the Location Uncertainty (LU) parametrization introduced by Mémin (Geophys Astrophys Fluid Dyn 108(2):119–146, 2014). Whilst both parametrizations are available for full-scale models, we study their reduced order versions obtained by projecting them on a complex vector Fourier mode triad of eigenfunctions of the curl. Remarkably, these two parametrizations lead to the same reduced order model, which we term the helicity-preserving stochastic triad (HST). This reduced order model is then compared with an alternative model which preserves the energy of the system, and which is termed the energy preserving stochastic triad (EST). These low-dimensional models are ideal benchmark models for testing new Data Assimilation algorithms: they are easy to implement, exhibit diverse behaviours depending on the choice of the coefficients and come with natural physical properties such as the conservation of energy and helicity.
9
Byun, Sung-Soo, e Peter J. Forrester. "Coulomb Gas Model, Sum Rules and Asymptotic Behaviours". In KIAS Springer Series in Mathematics, 55–68. Singapore: Springer Nature Singapore, 2024. http://dx.doi.org/10.1007/978-981-97-5173-0_4.
Testo completoAbstract (sommario):
AbstractThroughout this chapter we consider the Coulomb gas model (1.12) with general $$\beta > 0$$ β > 0 , for which we use the notation OCP, which stands for one-component plasma. The special case $$\beta = 2$$ β = 2 coincides with GinUE. The study of thermodynamic properties of the OCP requires the asymptotic expansion of the logarithm of the renormalised configuration integral for large N. This holds true for the Coulomb gas model confined to general domains. A conjectured universal logarithmic term, which is proportional to the Euler characteristic of the domain, is highlighted and a conjecture for the $$\sqrt{N}$$ N surface tension term in the case of disk geometry is also reported, as are some exact results for the energy per particle. In relation to the edge-scaled charge density, sum rules for the total charge and the dipole moment are given, and an asymptotic expansion of the density outside of the droplet is formulated, which as the multiplicative constant term involves the dimensionless free energy per particle. The final section of the chapter addresses sum rules and asymptotics associated with the truncated two-point correlation function, which is conveniently interpreted as the screening cloud about a fixed charge. Its Fourier transform gives the structure function, for which several terms in the small wavenumber expansion can be predicted. Also emphasised is distinct, slowly decaying, asymptotic behaviour of the truncated two-point correlation function at the boundary.
10
Marks II, Robert J. "Introduction". In Handbook of Fourier Analysis & Its Applications. Oxford University Press, 2009. http://dx.doi.org/10.1093/oso/9780195335927.003.0006.
Testo completoAbstract (sommario):
Jean Baptiste Joseph Fourier’s powerful idea of decomposition of a signal into sinusoidal components has found application in almost every engineering and science field. An incomplete list includes acoustics [1497], array imaging [1304], audio [1290], biology [826], biomedical engineering [1109], chemistry [438, 925], chromatography [1481], communications engineering [968], control theory [764], crystallography [316, 498, 499, 716], electromagnetics [250], imaging [151], image processing [1239] including segmentation [1448], nuclear magnetic resonance (NMR) [436, 1009], optics [492, 514, 517, 1344], polymer characterization [647], physics [262], radar [154, 1510], remote sensing [84], signal processing [41, 154], structural analysis [384], spectroscopy [84, 267, 724, 1220, 1293, 1481, 1496], time series [124], velocity measurement [1448], tomography [93, 1241, 1242, 1327, 1330, 1325, 1331], weather analysis [456], and X-ray diffraction [1378], Jean Baptiste Joseph Fourier’s last name has become an adjective in the terms like Fourier series [395], Fourier transform [41, 51, 149, 154, 160, 437, 447, 926, 968, 1009, 1496], Fourier analysis [151, 379, 606, 796, 1472, 1591], Fourier theory [1485], the Fourier integral [395, 187, 1399], Fourier inversion [1325], Fourier descriptors [826], Fourier coefficients [134], Fourier spectra [624, 625] Fourier reconstruction [1330], Fourier spectrometry [84, 355], Fourier spectroscopy [1220, 1293, 1438], Fourier array imaging [1304], Fourier transform nuclear magnetic resonance (NMR) [429, 1004], Fourier vision [1448], Fourier optics [419, 517, 1343], and Fourier acoustics [1496]. Applied Fourier analysis is ubiquitous simply because of the utility of its descriptive power. It is second only to the differential equation in the modelling of physical phenomena. In contrast with other linear transforms, the Fourier transform has a number of physical manifestations. Here is a short list of everyday occurrences as seen through the lens of the Fourier paradigm. • Diffracting coherent waves in sonar and optics in the far field are given by the two dimensional Fourier transform of the diffracting aperture. Remarkably, in free space, the physics of spreading light naturally forms a two dimensional Fourier transform. • The sampling theorem, born of Fourier analysis, tells us how fast to sample an audio waveform to make a discrete time CD or an image to make a DVD.
Atti di convegni sul tema "Termes de Fourier"
1
Lee, Hsin-Jung, Cheng-Che Lee, Yi-Min Yang, Wei-Yu Lee e Chieh-Hsiung Kuan. "Fourier Series Expansion with Correction Terms: An Innovative Algorithm for ECG Signal Analysis". In CLEO: Applications and Technology, JTu2A.191. Washington, D.C.: Optica Publishing Group, 2024. http://dx.doi.org/10.1364/cleo_at.2024.jtu2a.191.
Testo completoAbstract (sommario):
This study presents an advancement in signal processing for ECG signal analysis. By choosing the correct frequency and boundary conditions, the modified Fourier series expansion with correction terms can enhance the accuracy and reliability of signal reconstruction, enhancing signal accuracy for better medical diagnoses and treatment.
2
Pan, An, Shuhe Zhang e Aiye Wang. "Fourier ptychographic microscopy and its applications in whole slide imaging system via feature-domain computational framework". In Frontiers in Optics, FM5B.5. Washington, D.C.: Optica Publishing Group, 2024. https://doi.org/10.1364/fio.2024.fm5b.5.
Testo completoAbstract (sommario):
A feature-domain framework is reported for Fourier ptychographic microscopy, termed FD-FPM, to realize full-FOV reconstruction and reduce the accuracy requirement, achieving data acquisition of 4s/slide at 336nm spatial resolution with the FOV of 4.7mm diameter.
3
Fan, Yao, Jiasong Sun e Chao Zuo. "High-speed, high-throughput Fourier ptychographic microscopy with hybrid coherent/incoherent illumination". In Computational Optical Sensing and Imaging, CW3B.3. Washington, D.C.: Optica Publishing Group, 2024. http://dx.doi.org/10.1364/cosi.2024.cw3b.3.
Testo completoAbstract (sommario):
We propose an efficient synthetic aperture scheme for FPM, termed ESA-FPM, which employs both coherent and incoherent illuminations to maximize the efficiency of data utilization and achieves an imaging bandwidth of 3NA o b j λ requiring only 7 images.
4
Kubota, Kousuke, Ryusei Uchiyama, Wataru Kokuyama, Peter G. Schunemann e Yoshiaki Nakajima. "Generation of Frequency Comb Spanning 5.0-12.0 µm Based on a Bidirectional Dual-comb Fiber Laser". In JSAP-Optica Joint Symposia, 17p_A31_9. Washington, D.C.: Optica Publishing Group, 2024. https://doi.org/10.1364/jsapo.2024.17p_a31_9.
Testo completoAbstract (sommario):
Long-wavelength infrared (LWIR) spectroscopy has relied on Fourier transform spectroscopy (FTS) with incoherent thermal light sources. The thermal sources with low-brightness limit focusing ability, long-distance propagation, and spectroscopic sensitivity. Moreover, the FTS systems use mechanical moving stages, leading to a trade-off between spectral resolution and acquisition time. On the contrary, dual-comb spectroscopy (DCS) [1] surpasses conventional FTS in terms of bandwidth coverage, resolution, acquisition time, and sensitivity. However, DCS necessitates a complex laser source system to generate two optical combs with high relative frequency stability. To address this challenge, we have developed a bidirectional dual-comb fiber laser [2] capable of generating dual optical frequency combs from a single laser source.
5
Sharma, Kal Renganathan. "Mesoscopic Heat Conduction and Onset of Periodicity". In ASME 2003 Heat Transfer Summer Conference. ASMEDC, 2003. http://dx.doi.org/10.1115/ht2003-47391.
Testo completoAbstract (sommario):
Mesoscopic approach deals with study that considers temporal fluctuations which is often averaged out in a macroscopic approach without going into the molecular or microscopic approach. Transient heat conduction cannot be fully described by Fourier representation. The non-Fourier effects or finite speed of heat propagation effect is accounted for by some investigators using the Cattaneo and Vernotte non-Fourier heat conduction equation: q=−k∂T/∂x−τr∂q/∂t(1) A generalized expression to account for the non-Fourier or thermal inertia effects suggested by Sharma (5) as: q=−k∂T/∂x−τr∂q/∂t−τr2/2!∂2q/∂t2−τr3/3!∂3q/∂t3−…(2) This was obtained by a Taylor series expansion in time domain. Manifestation of higher order terms in the modified Fourier’w law as periodicity in the time domain is considered in this study. When a CWT is maintained at one end of a medium of length L where L is the distance from the isothermal wall beyond which there is no appreciable temperature change from the initial condition during the duration of the study the transient temperature profile is obtained by the method of Laplace transforms. The space averaged heat flux is obtained and upon inversion from Laplace domain found to be a constant for the the case obeying Fourier’s law; 1 − exp(−τ) using the Cattaneo and Vernotte non-Fourier heat conduction equation, and upon introduction of the second derivative in time of the heat flux the expression becomes, 1 − exp(−τ)(Sin(τ) + Cos(τ)). Thus the periodicity in time domain is lost when the higher order terms in the generalized Fourier expression is neglected.
6
Ballard, J., e D. A. Newnham. "Absorption spectra of cold vapours using FTS and collision cooling". In Fourier Transform Spectroscopy. Washington, D.C.: Optica Publishing Group, 1995. http://dx.doi.org/10.1364/fts.1995.ffa3.
Testo completoAbstract (sommario):
Spectra of polyatomic molecules, which are often very complex with many hot bands at room temperature , are significantly simplified if the sample can be cooled. The simplification aids analysis of the spectra in terms of rotational constants. Similarly spectral parameters such as line broadening coefficients, are needed to be known at cold temperatures for correct interpretation of many atmospheric measurements. However many polyatomic molecules also condense readily on cooling, so gas phase spectroscopy using conventional absorption cells at low temperatures is difficult, if not impossible due to the large negative temperature coefficient of SVP.
7
Carlotti, Massimo. "Recent Advances in Submillimeter Remote Sensing and Analysis". In Fourier Transform Spectroscopy. Washington, D.C.: Optica Publishing Group, 1995. http://dx.doi.org/10.1364/fts.1995.fsab3.
Testo completoAbstract (sommario):
The spectral region of submillimeter-waves (from 10 cm-1 to 200 cm-1) has proven to be suitable for the remote sensing of the atmosphere in terms of the number of species that can be observed, the intensity of the transitions that produce spectral features, and the diurnal coverage of the emission measurements that can be obtained. Fourier Transform spectrometers have been built for this purpose at the Istituto di Ricerca sulle Onde Elettromagnetiche (IROE) [1] and at the Smithsonian Astrophysical Observatory (SAO) [2]. Both instruments had several successful flights in which they measured the emission of the atmosphere, from a balloon-borne platform, with the limb-scanning observation technique. The analysis of the spectra has two main objectives: i) identification of atmospheric constituents through the assignment of the observed spectral features to specific transitions, ii) determination of the altitude distribution (profile) of the molecules that have been identified.
8
Prevenslik, Thomas. "The Fourier Law at the Macro and Nanoscale". In ASME 2013 4th International Conference on Micro/Nanoscale Heat and Mass Transfer. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/mnhmt2013-22030.
Testo completoAbstract (sommario):
The Fourier law implicitly assumes transient thermal disturbances are carried throughout the solid at an infinite velocity while not defining the carrier mechanism. Paradoxically, the phonon and electron carriers on which the Fourier law is based are limited to acoustic velocities. At the macroscale, the paradox is resolved by the thermal BB photons of QM that carry the Planck energy E = kT of the atoms in the disturbance throughout the solid at the speed of light. BB stands for blackbody and QM for quantum mechanics. The traditional Fourier equation in lattice temperature is expressed in terms of the Planck energy E of the atoms to show infinite carrier velocity is reasonably approximated by BB photons at the speed of light, thereby avoiding the unphysical alternative that absent BB photons the Fourier law is required to rely on thermal disturbances travelling at infinite velocity. Practically, the effect of BB photons on the accuracy of the Fourier solution is insignificant as the BB transient response of the semi-infinite solid is shown identical to that which includes the lag time caused by the speed of light. Fourier’s law is not applicable at the nanoscale as by QM the Planck energy of the atom is not available to be carried through the solid by the BB photon.
9
Fedorov, M. V., e J. Peatross. "Strong-Field Dipole Emission of an Ionized Electron in the Vicinity of a Coulomb Potential". In High Resolution Fourier Transform Spectroscopy. Washington, D.C.: Optica Publishing Group, 1994. http://dx.doi.org/10.1364/hrfts.1994.mc9.
Testo completoAbstract (sommario):
We have calculated three-dimensionally in the first Born approximation the interaction with a Coulomb potential of an electronic wave packet oscillating in a strong field. The initial wave packet was chosen to be a Gaussian with a 1/e2 probability-density radius of ro = 1.92ao (ao=Borh radius) which has an overlap of 98% with the hydrogen 1s state. The wave packet was expanded in terms of the Volkov states, and in the zeroth-order approximation it was considered to become suddenly free of the Coulomb potential, evolving in the strong oscillating electric field. The first-order correction to the electron motion was evaluated based on a perturbative treatment of the interaction with the Coulomb potential. Implicit in the calculation are the assumptions of the barrier-suppression ionization (BSI) model1 and the wave-packet-spreading photoionization model.2 The conditions for applicability of this approach are examined.
10
Ikeda, Daisuke. "LESSONS ON INFORMATION IN TERMS OF THE FOURIER TRANSFORM FOR PRIMARY-AGED STUDENTS". In 12th International Technology, Education and Development Conference. IATED, 2018. http://dx.doi.org/10.21125/inted.2018.0718.
Testo completoRapporti di organizzazioni sul tema "Termes de Fourier"
1
Lebel, D., e S. Talwar. Commission géologique du Canada: rapport sur les faits saillants 2018-2023. Natural Resources Canada/CMSS/Information Management, 2024. https://doi.org/10.4095/psu92y014m.
Testo completoAbstract (sommario):
Ce rapport de la Commission géologique du Canada (CGC) (2018-2023) présente les faits saillants des contributions scientifiques et technologiques en lien avec la responsabilité principale du mandat de RNCan, la science des ressources naturelles et l'atténuation des risques. Ce rapport résume les mesures proposées dans le cadre du plan stratégique de la CGC (2018-2023) et souligne les réalisations dans le cadre de chaque programme et service. La mission de la CGC est de fournir des informations géoscientifiques de pointe et faisant autorité dans le cadre de trois grandes priorités : Les connaissances géologiques des terres continentales et extracôtières du Canada; les géosciences pour le développement durable; et les géosciences pour assurer la sécurité du Canada.
2
Lebel, D., e S. Talwar. Geological Survey of Canada: highlight report 2018-2023. Natural Resources Canada/CMSS/Information Management, 2024. https://doi.org/10.4095/pqbsmh6xa1.
Testo completoAbstract (sommario):
Ce rapport de la Commission géologique du Canada (CGC) (2018-2023) présente les faits saillants des contributions scientifiques et technologiques en lien avec la responsabilité principale du mandat de RNCan, la science des ressources naturelles et l'atténuation des risques. Ce rapport résume les mesures proposées dans le cadre du plan stratégique de la CGC (2018-2023) et souligne les réalisations dans le cadre de chaque programme et service. La mission de la CGC est de fournir des informations géoscientifiques de pointe et faisant autorité dans le cadre de trois grandes priorités : Les connaissances géologiques des terres continentales et extracôtières du Canada; les géosciences pour le développement durable; et les géosciences pour assurer la sécurité du Canada.
3
Battams, Nathan. Les soins familiaux au Canada : une réalité et un droit. L’Institut Vanier de la famille, 2016. http://dx.doi.org/10.61959/nnvo5054f.
Testo completoAbstract (sommario):
Au moins une fois dans sa vie, chacun sera probablement appelé à prodiguer des soins à un proche, ou à en bénéficier. En règle générale, les membres de la famille sont les premiers à fournir et à encadrer de tels soins et, dans certains cas, à payer pour ceux-ci. Qu’il s’agisse de reconduire un frère ou une sœur à un rendez-vous médical, de préparer les repas pour un grand-parent ou encore de passer à l’école prendre un enfant qui ne se sent pas bien, s’occuper de la famille semble si naturel et englobe un si vaste éventail d’activités qu’on finit souvent par oublier qu’il s’agit de soins familiaux… Ces quelques exemples font pourtant partie de cette « réalité des soins » à laquelle nous sommes habitués. Les familles disposent d’une grande capacité d’adaptation, et les gens trouvent habituellement les moyens de mener de front leurs responsabilités, leurs engagements et leurs obligations multiples sur le plan professionnel et familial. Toutefois, puisque la plupart des aidants sont aussi sur le marché du travail à plein temps, il peut s’avérer difficile de concilier travail et prestation de soins. En vertu de la notion de « situation de famille » aux termes de la Loi canadienne sur les droits de la personne, l’employeur peut être contraint de consentir certaines mesures d’adaptation à son employé qui, ayant épuisé tous les autres recours raisonnables, serait contraint de choisir entre ses obligations professionnelles et les soins à prodiguer à un membre de sa famille. De fait, les droits de la personne assurent aux travailleurs un cadre de droits et la flexibilité nécessaire afin de conjuguer leurs obligations professionnelles et leur charge de soins.
4
Anderson, Gerald L., e Kalman Peleg. Precision Cropping by Remotely Sensed Prorotype Plots and Calibration in the Complex Domain. United States Department of Agriculture, dicembre 2002. http://dx.doi.org/10.32747/2002.7585193.bard.
Testo completoAbstract (sommario):
This research report describes a methodology whereby multi-spectral and hyperspectral imagery from remote sensing, is used for deriving predicted field maps of selected plant growth attributes which are required for precision cropping. A major task in precision cropping is to establish areas of the field that differ from the rest of the field and share a common characteristic. Yield distribution f maps can be prepared by yield monitors, which are available for some harvester types. Other field attributes of interest in precision cropping, e.g. soil properties, leaf Nitrate, biomass etc. are obtained by manual sampling of the filed in a grid pattern. Maps of various field attributes are then prepared from these samples by the "Inverse Distance" interpolation method or by Kriging. An improved interpolation method was developed which is based on minimizing the overall curvature of the resulting map. Such maps are the ground truth reference, used for training the algorithm that generates the predicted field maps from remote sensing imagery. Both the reference and the predicted maps are stratified into "Prototype Plots", e.g. 15xl5 blocks of 2m pixels whereby the block size is 30x30m. This averaging reduces the datasets to manageable size and significantly improves the typically poor repeatability of remote sensing imaging systems. In the first two years of the project we used the Normalized Difference Vegetation Index (NDVI), for generating predicted yield maps of sugar beets and com. The NDVI was computed from image cubes of three spectral bands, generated by an optically filtered three camera video imaging system. A two dimensional FFT based regression model Y=f(X), was used wherein Y was the reference map and X=NDVI was the predictor. The FFT regression method applies the "Wavelet Based", "Pixel Block" and "Image Rotation" transforms to the reference and remote images, prior to the Fast - Fourier Transform (FFT) Regression method with the "Phase Lock" option. A complex domain based map Yfft is derived by least squares minimization between the amplitude matrices of X and Y, via the 2D FFT. For one time predictions, the phase matrix of Y is combined with the amplitude matrix ofYfft, whereby an improved predicted map Yplock is formed. Usually, the residuals of Y plock versus Y are about half of the values of Yfft versus Y. For long term predictions, the phase matrix of a "field mask" is combined with the amplitude matrices of the reference image Y and the predicted image Yfft. The field mask is a binary image of a pre-selected region of interest in X and Y. The resultant maps Ypref and Ypred aremodified versions of Y and Yfft respectively. The residuals of Ypred versus Ypref are even lower than the residuals of Yplock versus Y. The maps, Ypref and Ypred represent a close consensus of two independent imaging methods which "view" the same target. In the last two years of the project our remote sensing capability was expanded by addition of a CASI II airborne hyperspectral imaging system and an ASD hyperspectral radiometer. Unfortunately, the cross-noice and poor repeatability problem we had in multi-spectral imaging was exasperated in hyperspectral imaging. We have been able to overcome this problem by over-flying each field twice in rapid succession and developing the Repeatability Index (RI). The RI quantifies the repeatability of each spectral band in the hyperspectral image cube. Thereby, it is possible to select the bands of higher repeatability for inclusion in the prediction model while bands of low repeatability are excluded. Further segregation of high and low repeatability bands takes place in the prediction model algorithm, which is based on a combination of a "Genetic Algorithm" and Partial Least Squares", (PLS-GA). In summary, modus operandi was developed, for deriving important plant growth attribute maps (yield, leaf nitrate, biomass and sugar percent in beets), from remote sensing imagery, with sufficient accuracy for precision cropping applications. This achievement is remarkable, given the inherently high cross-noice between the reference and remote imagery as well as the highly non-repeatable nature of remote sensing systems. The above methodologies may be readily adopted by commercial companies, which specialize in proving remotely sensed data to farmers.
5
Dolby, G. Palynological analysis of Carboniferous outcrop and corehole samples from the 1993–1995 Magdalen Basin NATMAP Project, with updated data files, locality data, and lists of taxa identified, Prince Edward Island, Nova Scotia, New Brunswick, and Quebec. Natural Resources Canada/CMSS/Information Management, 2024. http://dx.doi.org/10.4095/pcqvf1214e.
Testo completoAbstract (sommario):
Le projet NATMAP du bassin de la Madeleine était un effort de coopération et de collaboration visant à aborder l'histoire géologique de la fin du Paléozoïque et le potentiel de ressources de l'ouest du bassin des Maritimes. Ce bassin se trouve sous une grande partie du golfe du Saint-Laurent et peut être étudié à terre dans certaines parties de cinq provinces de l'est du Canada. Environ trente participants, représentant les services géoscientifiques régionaux et nationaux du gouvernement, des universités et du secteur privé, ont entrepris des études multidisciplinaires des parties terrestres du bassin entre 1993 et 1995. Des études stratigraphiques de ce vaste bassin sédimentaire ont soutenu cet effort collectif. De telles études ont été historiquement étayées par la paléontologie des invertébrés, qui permet de situer les roches dans une époque géologique relative. Comme les fossiles utilisés plus traditionnellement sont largement indisponibles dans un bassin dominé par des roches non marines, la palynologie, en particulier l'étude des spores et du pollen, a fourni un outil idéal adapté à l'étude des roches terrestres. Graham Dolby, consultant et l'un des deux seuls spécialistes en palynologie du Carbonifère au Canada à cette époque, a apporté un soutien fondamental aux études tout au long du projet du Bassin de la Madeleine. Les matériaux analysés provenaient en grande partie d'affleurements rocheux de la Nouvelle-Écosse et du sud-est du Nouveau-Brunswick, où se concentraient les activités du projet. La palynologie de certains puits d'exploration forés en Nouvelle-Écosse, à l'Île-du-Prince-Édouard et au Nouveau-Brunswick, ainsi que de plusieurs puits d'hydrocarbures profonds forés au large dans le golfe du Saint-Laurent, a également été analysée. Le but de ce fichier ouvert à plusieurs composants est de rendre publiques les contributions NATMAP de Dolby. Les données palynologiques présentées dans ce dossier ouvert sont aussi précieuses aujourd'hui qu'elles l'étaient dans les années 1990, mais au cours des trente années qui ont suivi, des améliorations significatives dans la compréhension de la distribution du pollen et dans l'application à la stratigraphie du bassin des Maritimes ont été réalisées. Dans la présente version, Dolby a mis à jour les implications stratigraphiques qui peuvent être tirées de ses analyses antérieures des échantillons NATMAP pour refléter des zonages plus actuels. Les données palynologiques mises à jour ont été appliquées par Atkinson et al. (2020), dans leur évaluation des ressources pétrolières du bassin des Maritimes, dans le cadre du programme de projets de conservation marine. Pendant que le projet NATMAP du bassin de la Madeleine était opérationnel, les données palynologiques et l'évaluation de la position biostratigraphique ont été renvoyées au projet en fonction uniquement de l'identification de l'échantillon ou du nom du puits, car les emplacements des échantillons soumis étaient bien connus des géologues participants. Pour remédier à ce manque de données de localisation, les données sommaires, y compris la plupart des emplacements d'échantillonnage ainsi que les listes de taxons récupérés, ont été extraites de BASIN, une base de données d'archives majeure de la Commission géologique du Canada – Atlantique. Ces données sont fournies sous forme de feuille de calcul et sont accessibles dans BASIN ici : https://basin.marine-geo.canada.ca/wells/natmap_index_e.php