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Literatura académica sobre el tema "Filtre spatial"

Autor: Grafiati

Publicado: 21 de diciembre de 2024

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Artículos de revistas sobre el tema "Filtre spatial"

GOBERT, J., J. F. DEROUBAIX y M. SEIDL. "Un filtre planté dans le bois de Boulogne : quelle intégration socio-spatiale d’un objet-frontière ?" Techniques Sciences Méthodes 12 (20 de enero de 2023): 55–72. http://dx.doi.org/10.36904/202212055.

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Le déversoir d’orage Bugeaud situé dans le bois de Boulogne a fait l’objet d’une rénovation importante. Alors qu’il déversait auparavant directement en Seine les eaux pluviales d’un tronçon du boulevard périphérique, la Ville de Paris l’a récemment aménagé en l’équipant d’un système de stockage et de traitement de ces eaux par un filtre planté de roseaux avant leur rejet dans le réseau hydrographique du bois de Boulogne et à terme en Seine. Le projet Life Adsorb accompagne la réalisation et évalue l’efficacité de l’ouvrage, notamment sur l’abattement des micropolluants. Il intègre un volet sociologique sur les conditions d’appropriation de l’ouvrage par les services techniques de la collectivité ainsi que par les riverains alentours et les visiteurs du Bois. Afin d’analyser l’insertion socio-spatiale du filtre planté, nous avons eu recours à un cadre d’analyse fondé sur l’acceptabilité sociale, en différenciant l’enjeu et le problème d’acceptabilité. Nous avons donc regardé, d’une part, l’ouvrage comme un objet socio-technique qui, de sa conception à sa mise en service, passe par différentes étapes et réinterprétations (sociologie de la traduction et de l’innovation). D’autre part, nous avons observé comment cet ouvrage se confrontait à de nouveaux collectifs une fois construit. In fine, l’article illustre l’ambiguïté existante entre le souhait de faire de cet objet un « projet vitrine » d’une ville innovante et durable et la recherche d’invisibilisation par le paysagement. De fait, cet article montre comment ce type d’ouvrage assez commun agit comme un objet-frontière à l’intersection des savoir-faire et pratiques des différents services qui interviennent dans sa conception et sa maintenance, et des usagers. La connaissance acquise sur la conception et la maintenance de techniques alternatives souffre de ne pas être assez capitalisée au niveau des collectivités d’une part et entre collectivités d’autre part. Leur pleine insertion socio-spatiale reste dépendante d’une reconfiguration des organisations qui les reçoivent.

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Xin He, Xin He, Jian Zhou Jian Zhou, Xiaoming Nie Xiaoming Nie y Xingwu Long Xingwu Long. "Filtering characteristics of spatial filter for spatial filtering velocimeter". Chinese Optics Letters 13, n.º 6 (2015): 060702–60705. http://dx.doi.org/10.3788/col201513.060702.

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Sivakumar, R., M. K. Gayathri y D. Nedumaran. "Speckle Filtering of Ultrasound B-Scan Images- A Comparative Study of Single Scale Spatial Adaptive Filters, Multiscale Filter and Diffusion Filters". International Journal of Engineering and Technology 2, n.º 6 (2010): 514–23. http://dx.doi.org/10.7763/ijet.2010.v2.174.

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Ying Zhang, Ying Zhang, Hongji Qi Hongji Qi, Kui Yi Kui Yi, Yanzhi Wang Yanzhi Wang, Hongbo He Hongbo He y Jianda Shao Jianda Shao. "Design and fabrication of thin-film spatial filter". Chinese Optics Letters 12, s2 (2014): S20501–320504. http://dx.doi.org/10.3788/col201412.s20501.

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Dev, Ashwani y George A. McMechan. "Spatial antialias filtering in the slowness-frequency domain". GEOPHYSICS 74, n.º 2 (marzo de 2009): V35—V42. http://dx.doi.org/10.1190/1.3052115.

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A rigorous, explicit spatial antialias filter is designed and applied to spatially coarsely sampled seismic data by removing all energy above the first Nyquist wavenumber, and aliased energy that is folded back across the Nyquist, in the horizontal slowness-frequency domain. The spatial filtering in the slowness-frequency domain is explicit, free from any event linearity assumption, and does not require any interpolation. The spatially aliased energy is dispersive, and present at small and large slownesses. Comparison of the output data after antialias spatial filtering, with output data after conventional antialias frequency filtering, shows that the filter removes the spatially aliased frequencies selectively at each slowness; antialias low-pass frequency filtering under- or overcorrects for spatial aliasing at all slownesses. A seismic gather can be spatially dealiased only at the expense of wavelet spectral changes; dealiasing and preservation of amplitude variations with offset are not simultaneously possible.

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Cantet, Philippe, M. A. Boucher, S. Lachance-Coutier, R. Turcotte y V. Fortin. "Using a Particle Filter to Estimate the Spatial Distribution of the Snowpack Water Equivalent". Journal of Hydrometeorology 20, n.º 4 (29 de marzo de 2019): 577–94. http://dx.doi.org/10.1175/jhm-d-18-0140.1.

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Abstract A snow model forced by temperature and precipitation is used to simulate the spatial distribution of snow water equivalent (SWE) over a 600 000 km2 portion of the province of Quebec, Canada. We propose to improve model simulations by assimilating SWE data from sporadic manual snow surveys with a particle filter. A temporally and spatially correlated perturbation of the meteorological forcing is used to generate the set of particles. The magnitude of the perturbations is fixed objectively. First, the particle filter and direct insertion were both applied on 88 sites for which measured SWE consisted of more or less five values per year over a period of 17 years. The temporal correlation of perturbations enables us to improve the accuracy and the ensemble dispersion of the particle filter, while the spatial correlation leads to a spatial coherence in the particle weights. The spatial estimates of SWE obtained with the particle filter are compared with those obtained through optimal interpolation of the snow survey data, which is the current operational practice in Quebec. Cross-validation results as well as validation against an independent dataset show that the proposed particle filter enables us to improve the spatial distribution of the snow water equivalent compared with optimal interpolation.

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Kim, J. S. "Mitigation of Inter-Symbol Interference in Underwater Acoustic Communication Using Spatial Filter". Journal Of The Acoustical Society Of Korea 33, n.º 1 (2014): 48. http://dx.doi.org/10.7776/ask.2014.33.1.048.

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Hariharan, P. y M. Roy. "Improved pinhole spatial filter". Optics & Laser Technology 39, n.º 1 (febrero de 2007): 155–56. http://dx.doi.org/10.1016/j.optlastec.2005.04.002.

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Donohoe, Aaron y David S. Battisti. "The Amplitude Asymmetry between Synoptic Cyclones and Anticyclones: Implications for Filtering Methods in Feature Tracking". Monthly Weather Review 137, n.º 11 (1 de noviembre de 2009): 3874–87. http://dx.doi.org/10.1175/2009mwr2837.1.

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Abstract The “background” state is commonly removed from synoptic fields by use of either a spatial or temporal filter prior to the application of feature tracking. Commonly used spatial and temporal filters applied to sea level pressure data admit substantially different information to be included in the synoptic fields. The spatial filter retains a time-mean field that has comparable magnitude to a typical synoptic perturbation. In contrast, the temporal filter removes the entire time-mean field. The inclusion of the time-mean spatially filtered field biases the feature tracking statistics toward large cyclone (anticyclone) magnitudes in the regions of climatological lows (highs). The resulting cyclone/anticyclone magnitude asymmetries in each region are found to be inconsistent with the unfiltered data fields and merely result from the spurious inclusion of the time-mean fields in the spatially filtered data. The temporally filtered fields do not suffer from the same problem and produce modest cyclone/anticyclone magnitude asymmetries that are consistent with the unfiltered data. This analysis suggests that the weather forecaster’s assertion that cyclones have larger amplitudes than anticyclones is due to a composite of a small magnitude asymmetry in the synoptic waves and a large contribution from inhomogeneity in the background (stationary) field.

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Zhou, Hau‐wei. "Traveltime tomography with a spatial‐coherency filter". GEOPHYSICS 58, n.º 5 (mayo de 1993): 720–26. http://dx.doi.org/10.1190/1.1443456.

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Spatially incoherent small wavelengths in a velocity tomogram are usually noise that could destabilize an iterative traveltime tomographic process. By defining the number of connected cells of similar values in an image as the spatial‐coherency (SC) value of these cells, an SC filtering is introduced in this paper to suppress incoherent features in an image. An SC filter first quantifies the SC value of all image cells and then conducts a discriminative moving‐average over cells of low SC values. It is demonstrated that such an SC filtering of the intermediate‐stage tomograms may enhance the robustness of the iterative tomographic process to noise. The SC values can be used in general to deconvolve an image of any dimension into components of different lengths in spatial connectivity.

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Tesis sobre el tema "Filtre spatial"

Guerrero, Enriquez Rubén Dario. "Etude des filtres miniatures LTCC High K en bandes L&S". Thesis, Brest, 2016. http://www.theses.fr/2016BRES0036/document.

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Dans les systèmes actuels de communication, qu’ils soient terrestre ou spatial, qu’ils soient mobile ou fixe, il y a un réel intérêt à développer des front-ends radiofréquences et hyperfréquences miniatures et performants. Ceci s’applique en particulier aux dispositifs de filtrage où l’encombrement et les facteurs de qualité sont clairement antagonistes. Pour les bandes de fréquences basses aux alentours du GHz, les longueurs d’onde restent encore importantes, rendant difficiles les efforts de miniaturisation. D’autre part il faut aussi s’assurer que ces filtres viendront s’interconnecter aisément avec les autres composants du système, notamment les actifs.Pour toutes ces raisons, le développement de structures de filtres multicouches utilisant des substrats à haute permittivité (εr = 68) selon une approche LTCC apparait comme une alternative intéressante. Elle peut en effet conduire à une réduction significative de l'empreinte (footprint) sans pour autant trop nuire aux performances électriques.Dans le cadre de ce travail, deux structures de filtres multicouches ont été développées pour répondre à des spécifications proposées en bandes L et S, par un équipementier du spatial. Ces filtres ont pour caractéristiques principales un haut niveau de rejection et des faibles pertes dans la bande passante. Pour atteindre les spécifications, un filtre SIW empilé verticalement et un filtre à stubs en court-circuit en configuration triplaque ont été étudiés. Le filtre SIW se distingue par un facteur de qualité élevé, ce qui entraîne des faibles pertes d’insertion et une bonne platitude. La solution à stub permet quant à elle de réduire l’encombrement mais au prix d’un impact sur les performances électriques. Dans les deux cas on tire parti de la souplesse offerte par la technologie LTCC, puisqu’elle offre finalement un degré de liberté supplémentaire, par rapport à une approche planaire classique. Si dans le cas SIW, c’est surtout l’architecture topologique qui a été étudiée finement pour pouvoir agencer et coupler douze cavités, dans le cas du filtre à stub une synthèse mettant à profit tous les degrés de liberté offerts a été spécifiquement développée.Compte tenu de la complexité des filtres, notamment à cause de l’ordre élevé et de la mise en oeuvre de murs « électriques » à partir d’arrangements de via spécifiques, une attention particulière doit être apportée lors des phases de simulation et d’optimisation. De plus la très forte permittivité du substrat ne permet pas d’utiliser de ligne 50 Ohms. Enfin les transitions constituent un point dur de l’exercice surtout dans le cas SIW.Cette thèse co-financée par le CNES (Centre National d'Etudes Spatiales) et Thales Alenia Space, était accompagnée par un projet R&T financé par le CNES. Le fondeur allemand Via Electronic avait en charge la fabrication des filtres
In current communication systems, whether terrestrial or spatial, whether fixed or mobile, there is a real interest in developing high performance miniature RF front-ends. This is applied in particular to filter devices, in which the size and the quality factors are clearly in conflict. For low frequency bands around the GHz, the wavelengths remain significant, making it difficult the miniaturization efforts. On the other hand, we must also ensure that these filters will be easily interconnected with other other system components, including active devices.For all these reasons, the development of multilayer filter structures using high permittivity substrates (Er = 68) in an LTCC approach is consolidated as an interesting alternative. It may lead to a significant footprint reduction without decreasing the electrical performances.As part of this work, two multilayer filter structures have been developed to meet the given specifications in L and S bands, given by a space manufacturer. These filters have as main features a high rejection level and low losses in the passband. To meet the specifications, a vertically stacked SIW filter and a short-circuited stubs filter in a stripline configuration were studied. The SIW filter is characterized by a high quality factor, which results in low insertion loss and good flatness. The stubs filter allows in contrast to reduce the footprint but at the price of impacting the electrical performance. In both cases we take advantage of the flexibility offered by the LTCC technology as it finally provides an additional freedom degree compared to a conventional planar approach. For the SIW filter, the topological architecture was studied and designed in detail, to be able to arrange and synthetize couplings between twelve cavities. In a similar way, for the stub filter a synthesis that takes profit of all the offered freedom degrees was developed.Given the filters complexity, especially due to the high order and the implementation of “electrical walls" based on specific vias patterns, a close attention must be paid during the simulation and optimization phase. In addition, the high permittivity substrate does not allow to conceive 50-Ohms lines. Finally, access transitions constitute a challenging task, especially for the SIW case.This thesis was co-funded by CNES (Centre National d'Etudes Spatiales) and Thales Alenia Space, and was accompanied by an R&T project funded by CNES. The German foundry Via Electronic was responsible for the filters fabrication

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Renaud, Denis. "Caractérisation du propulseur PEGASES : diagnostics du filtre magnétique et du faisceau : optimisation de la géométrie". Thesis, Orléans, 2016. http://www.theses.fr/2016ORLE2018/document.

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Le propulseur de PEGASES est un moteur ionique qui diffère des autres technologies. La particularité de ce propulseur est l’utilisation d’un gaz électronégatif, à savoir le SF₆. Un champ magnétique est utilisé pour piéger les électrons et augmenter la production des ions négatifs. Le plasma résiduel à faible densité d’électrons, dit plasma ion-ion, permet l’extraction et l’accélération des ions positifs et négatifs. Les ions recombinent par paire dans le faisceau et garantissent la neutralité dans le faisceau. L’extraction d’une quantité équivalente d’ions positifs et négatifs permet ainsi d’éviter l’emploi d’un neutraliseur. Afin d’étudier les propriétés du faisceau ionique, une sonde EXB est utilisée pour diagnostiquer les vitesses et les proportions des molécules formées puis accélérées. La sonde n’étant pas parfaite, une calibration permet de déterminer avec précision les différentes espèces présentes dans le plasma. La présence d’ions positifs et négatifs ont pu être démontré via des mesures par sonde EXB. La technique de photo-détachement par laser est employée afin d’étudier les ions de charge négative. Cette méthode permet d’obtenir la proportion d’ions négatifs par rapport aux électrons. L’électronégativité dans ce type de décharge est très importante. La technique a montré l’importance du filtre magnétique. Cependant, la configuration de celui-ci n’est pas optimale puisqu’une structure est créée par la dérive électronique. Un nouveau propulseur à géométrie circulaire a été conçu, construit et testé. Cette nouvelle architecture utilise une dérive électronique fermée circulaire grâce à des aimants permanents. Les expériences ont validé le concept et montre l’importance d’une géométrie en anneau
The PEGASES ion thruster differs from standard electric propulsion technologies through its use of electronegative gases, such as SF₆, as a propellant. Its operation relies on the trapping of electrons using a magnetic field and the creation of a plasma dominated by positive and negative ions. These ions are alternately accelerated to produce thrust, and later undergo a recombination to ensure beam neutrality. This thruster eliminates the need for an electron-producing neutralizer, which is a standard feature in other sources such as the Hall thruster. This thesis is divided into three parts. The first describes the development and implementation of a new EXB probe for the study of the ion beam properties, the identification of the beam chemical composition and the verification of the presence of negative and positive ion species. The second part concerns the design and application of a new laser photodetachment diagnostic for the measurement of the negative ion fraction. Lastly, a new ion-ion thruster with a circular geometry, known as AIPE, has been designed, constructed and successfully tested. This prototype eliminates the plasma asymmetry present in PEGASES and reveals the importance of the magnetic filter to source operation

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Edjeou, René Tchalim. "Contribution à la réalisation d'un dispositif à transport acoustique de charges". Valenciennes, 1999. https://ged.uphf.fr/nuxeo/site/esupversions/f6344825-6189-4bcd-a9c7-83534f301ffe.

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Dans ce mémoire nous présentons une étude depuis la modélisation jusqu'à la réalisation et la caractérisation d'un dispositif de transport acoustique de charges base sur une structure hemt de la filière de l'arséniure de gallium (GaAs). Bénéficiant des propriétés semi-conductrice et piézoélectrique du GaAs, le dispositif utilise une onde acoustique de surface, générée et détectée directement par un transducteur à peignes interdigites, pour confiner et transporter les charges dans un canal à proximité de la surface. Après un rappel des caractéristiques des ondes acoustiques de surface (génération, propagation et détection) dans les hétéro structures piézoélectriques, nous avons exposé les bases physiques et le principe de fonctionnement de transport acoustique de charges. L’étude s'inscrit dans la perspective de la réalisation de circuits monolithiques à caractère innovant qui permet l'intégration sur un même substrat, d'autres composants. Nous développons, à partir d'un modèle de simulation bidimensionnelle, une analyse des phénomènes de transport de charge dans les hétéros structures. Ce modèle théorique est basé sur la résolution des équations fondamentales des semi-conducteurs déduites des équations de Poisson, de continuités et de densités de courant, pour les électrons et les trous. Basés sur ces études, nous avons mis au point les différentes étapes technologiques et réalisé deux prototypes a 178 MHz. Les mesures effectuées ont permis de vérifier la fréquence centrale de propagation de l'onde acoustique et les temps de retard, de déterminer les pertes d'insertions et les impédances des transducteurs, et enfin de confirmer le transport acoustique d'un signal injecte. Enfin sont présentés deux types de circuits mixtes : un modulateur multi-puits quantiques spatial bidimensionnel et un filtre transversal programmable, en cours de développement au laboratoire, pour répondre aux besoins des processeurs de signaux de haute vitesse utilisés dans les systèmes de communication moderne et radars.

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Hecquet, Christophe. "Conception, réalisation et métrologie de miroirs multicouches pour l'extrême ultraviolet résistants aux environnements du spatial et des sources EUV". Phd thesis, Université Paris Sud - Paris XI, 2009. http://tel.archives-ouvertes.fr/tel-00387144.

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Les rayonnements extrêmes ultraviolets (EUV), gamme de longueurs d'onde comprises entre 13 nm et 40 nm, offrent de nombreuses applications scientifiques et technologiques. Celles-ci se sont développées par exemple en physique des plasmas (source à génération d'harmoniques d'ordre élevé, laser X), en astrophysique solaire ou en photolithographie EUV.
Les travaux présentés portent sur la conception, la réalisation et la métrologie de miroirs multicouches périodiques. La motivation principale de cette étude est de mettre en place un cycle de développement prenant en compte à la fois les propriétés optiques du pouvoir réflecteur des revêtements réfléchissants (réflectivité, sélectivité spectrale, atténuation) mais aussi l'environnement d'utilisation des optiques.
Afin d'améliorer les propriétés de sélectivité spectrale, de nouvelles structures multicouches périodiques ont été développées. Elles se caractérisent par un pouvoir réflecteur qui réfléchit bien deux régions spectrales ajustables et introduit des atténuations paramétrables.
L'effet de l'environnement sur la stabilité des performances est particulièrement critique pour les optiques de collection. L'ajout de matériaux barrières a permis de stabiliser les performances du pic de réflectivité pendant plus de 200 h à 400°C et de réduire l'influence des autres facteurs d'instabilité sur le pouvoir réflecteur.
De plus, toutes les structures réalisées ont été évaluées avec succès en environnements climatiques sévères.

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Möller, Torsten. "Spatial domain filter design /". The Ohio State University, 1999. http://rave.ohiolink.edu/etdc/view?acc_num=osu1488190109868038.

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Barufi, Ana Maria Bonomi. "Dimensões regionais da mortalidade infantil no Brasil". Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/12/12140/tde-26022010-093526/.

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O desenvolvimento pode ser estudado sob diversas perspectivas. Dentre estas, destaca-se a de Amartya Sen, na qual o objetivo maior de uma política de desenvolvimento é o de expandir a liberdade de escolha dos indivíduos. Partindo da ideia de ampliação das capabilities, define-se uma das dimensões consideradas como essenciais, a saúde, mais especificamente a mortalidade infantil, como objeto de estudo. Um dos papéis do Estado deve ser o de garantir a provisão de serviços de saúde para todos os indivíduos, já que ela pode ser classificada como um bem meritório. Em busca dos determinantes do padrão regional recente da mortalidade infantil no Brasil, utiliza-se o modelo de determinantes proximais proposto por Mosley e Chen (1984), no qual os fatores socioeconômicos influenciam indiretamente o resultado observado da variável de interesse. No Brasil, houve uma redução expressiva dos níveis de mortalidade infantil nas últimas décadas, mas ainda assim persiste uma intensa desigualdade regional. Com o objetivo de comparar os resultados alcançados localmente no país, é necessário incluir a dimensão espacial em um modelo econométrico para que os problemas decorrentes da dependência espacial possam ser evitados. Após utilizar o filtro espacial para tanto, estimando cross-sections para 1980, 1991 e 2000, o trabalho conclui que a infraestrutura de saúde, enquanto medida pelo número de leitos e de estabelecimentos perdeu importância na explicação do padrão da mortalidade infantil ao longo do tempo. Em contrapartida, as variáveis socioeconômicas tornaram-se mais relevantes e significativas. A implicação mais direta disso é que futuras políticas devem buscar melhorar o acesso das famílias aos serviços públicos de saneamento, reduzir a pobreza e a desigualdade e aumentar o nível educacional da população. Ou seja, o estímulo à prevenção familiar contra problemas que possam ocasionar a morte prematura torna-se cada vez mais essencial.
Development can be understood from many perspectives. Among those, the one proposed by Amartya Sen states that a development policy should aim at expanding the freedom of individuals, and this goal can be achieved by the expansion of capabilities. With this conceptual framework in mind, health, more specifically infant mortality, is chosen as a measure of development and as the object of study. The Government should guarantee the provision of health services, as they consist in meritory goods. Mosley and Chen (1984) propose a theoretical framework to study infant mortality based on the proximal determinants, in which the socioeconomic factors affect the result observed indirectly. In Brazil there has been a substantial reduction of the average levels of infant mortality rates in the last decades. However, there is still a significant regional inequality. Econometric models for 1980, 1991 and 2000 are estimated including a spatial filter in order to account for the spatial dependency observed in the data. The study concludes that health infrastructure lost its explanative power for the differences in infant mortality rate among the localities. On the other hand, socioeconomic variables have become more relevant and significant. It means that future public policies must try to improve the access of the families to public facilities, reduce poverty and inequality and improve educational levels. Therefore, the family-based prevention against health problems should be stimulated, helping to avoid premature death

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Feuray, William. "Multiplexeurs Accordables pour Application Spatiale". Thesis, Limoges, 2017. http://www.theses.fr/2017LIMO0115/document.

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Cette thèse a pour but d’étudier le principe d’un multiplexeur de sortie accordable pour la charge utile d’un satellite de télécommunication. La première étape consiste à analyser les principales topologies de multiplexeur de sortie utilisables et les comparer pour en retirer le meilleur candidat pour cette application. Par la suite, diverses études ont été menées sur des composants passifs imprimés en 3D plastique et métallisés de diverses manières, en cherchant à comprendre comment améliorer au mieux les résultats de ces prototypes. La dernière partie de ce manuscrit détaille la conception d’un multiplexeur à deux canaux pouvant être utilisé sur trois états différents en large bande à 19 GHz. Ces états sont créés par des bandes passantes relatives variant de 1,6 à 4,8 % et une réalisation de deux maquettes sert de preuves de concept et de performance (une en plastique métallisé et la seconde en aluminium usiné)
This thesis is about study of tunable output multiplexer principle for telecommunication satellite payload. The first step is analysis of the main topologies of output multiplexers and to compare them to conclude with the best candidate. Then, several studies were conducted on 3D plastic printed passive components with specific metallizations, searching how to improve results in term of losses and precision. Last part detailed two channels multiplexer design which can be used on three different states of relative bandwidth from 1.6 to 4.8 % at 19 GHz, and realization of two concept proof prototypes (one in metallized 3D printed plastic and another one in machined aluminum)

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Jolly, Nicolas. "Filtres accordables volumiques à forts facteurs de qualité pour des applications spatiales". Thesis, Limoges, 2015. http://www.theses.fr/2015LIMO0103/document.

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A l'heure où la demande en quantité d'informations et le nombre d'utilisateurs explosent, toujours avec des limitations en allocation en fréquence et bande passante, les systèmes de télécommunication tendent à optimiser la gestion de leur capacité en s'orientant vers des systèmes reconfigurables. Dans le cas des filtres d'OMUX, apporter de l'accordabilité en conservant d'excellentes performances électriques, thermiques et mécaniques soulève de nombreuses difficultés.Nous avons dans un premier temps démontré la faisabilité sur un filtre à saut de canal à bande passante constante par le biais d'une cavité métallique chargée par un perturbateur en alumine en mouvement de rotation. Ensuite, nous avons proposé des solutions pour avoir un contrôle de la fréquence et de la bande passante en se basant sur la translation de matériaux diélectriques. Les facteurs de qualité mis en jeu sont de l'ordre de la dizaine de milliers. Enfin nous avons tiré profit de l'évolution des technologies d'impression plastique 3D pour valider différents concepts de filtres accordables
At a time when the amount of information and the number of users go through the roof in telecommunication market, the telecommunication systems tend to improve the management of their capacity by moving toward reconfigurable RF devices. However frequency and bandwidth allocated are still restricted. Regarding tunable OMUX filters, the actuation systems generally degrade the overall performances of the device and raise questions in terms of mechanic and thermic.We first demonstrated the feasability of a two state filter with constant narrowband, using a dielectric material (alumina) in rotation inside a metallic housing. Then, we suggested solutions to control both frequency and bandwidth with the translation of a ceramics. We deal with quality factor in the range of ten of thousands for these applications. Eventually, we validated some principle for tunable filters thanks to the efficiency of 3D plastic printer

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Gorea, Andrei. "Le codage visuel des constituants "elementaires" de l'image : approche psychophysique". Paris 6, 1986. http://www.theses.fr/1986PA066473.

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L'image, telle que nous la percevons, resulte d'un traitement en parallele de ses constituants "elementaires" suivi de leur synthese en des ensembles significatifs. Ce travail developpe les problemes theoriques souleves par la caracterisation de ces "primitives" visuelles et par le processus de segmentation en general, presente plusieurs classes de modeles de la detection et de l'identification de ces primitives et discute de la compatibilite de leurs predictions quantitatives avec, d'une part, les resultats de la psychophysique et, d'autre part, avec ce que nous savons sur la neurophysiologie des voies visuelles

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Hamidouche, Louiza. "Spectroscopie micro-onde pour la mesure des charges d'espace à haute résolution spatiale dans les isolants en couche mince". Electronic Thesis or Diss., Sorbonne université, 2018. http://www.theses.fr/2018SORUS275.

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L'objectif de cette thèse est de proposer et de tester une nouvelle méthode pour la mesure des charges d'espace dans les isolants en couche mince avec une haute résolution spatiale. La méthode proposée est appelée Reflectométrie Électro-Acoustique ou en anglais Electro-Acoustic Reflectometry (EAR). La méthode EAR est basée sur le couplage électro-élastique de l'échantillon testé. L'excitation et la mesure sont électriques et se font dans le domaine fréquentiel. Une instrumentation micro-onde est employée pour des mesures à haute fréquence. Le principe de la mesure repose sur le fait que lorsque les charges sont excitées par un champ électrique appliqué, elles génèrent des ondes ultrasonores. L'énergie consommée par la génération de ces ondes produit une signature dans la réflexion par l'échantillon de l'excitation électrique. C'est cette signature qui est utilisée pour retrouver la distribution des charges d'espace par une simple transformée de Fourier inverse. Un banc de mesure composé d'un analyseur de réseaux vectoriel, d'un porte-échantillon dédié et d'une interface d'acquisition a permis de tester la méthode EAR. Les résultats obtenus sont prometteurs. La résolution spatiale démontrée est de 1.2µm en volume. Elle dépasse la meilleure résolution spatiale actuelle obtenue avec les méthodes ultrasonores conventionnelles existantes d'un facteur d'environ 10. Pour améliorer encore la résolution spatiale de la méthode EAR, il est nécessaire d'augmenter la plage de fréquences de mesure. Une approche est proposée pour résoudre les problèmes rencontrés à haute fréquence
The objective of this thesis is to come up with and test a new method for the measurement of space charge in very thin insulating films with a high spatial resolution. The proposed method is called Electro-Acoustic Reflectometry (EAR) method. The EAR method relies on the electro-elastic coupling of the sample under test. Both excitation and measurement are of electrical nature and are performed in frequency domain. A microwave setup is used for high frequency measurements. The measurement principle is the generation of ultasonic waves when space charge undergoes an applied electrical field. The energy that is used up in the generation of these waves leaves a feature in the reflection of the electrical excitation. It is this feature that is used to find the space charge distribution by a simple inverse Fourier transform. A measurement setup comprising a vector network analyser, a dedicated sample holder and an acquistion interface allows to test the EAR method. The obtained results are promising. A bulk spatial resolution of 1.2µm has been demonstrated. It exceeds the current best spatial resolution achieved by existing conventionnal ultrasonic methods by a factor of about 10. To further enhance the spatiale resolution of the EAR method, it is necessary to broaden the measurement frequency range. An approach to deal with the problems occuring at high frequnecy is proposed

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Libros sobre el tema "Filtre spatial"

T, Smith Mark J. y United States. National Aeronautics and Space Administration., eds. Spatially-varying IIR filter banks for image coding. [Washington, DC: National Aeronautics and Space Administration, 1992.

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Griffith, Daniel A. Spatial regression analysis on the PC: Spatial statistics using SAS. Washington, D.C: Association of American Geographers, 1993.

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Griffith, Daniel A. Spatial regression analysis on the PC: Spatial statistics using Minitab. [Ann Arbor, Mich., U.S.A.] (2790 Briarcliff, Ann Arbor 48105): Institute of Mathematical Geography, 1989.

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Decker, Arthur J. Neural-network-directed alignment of optical systems using the laser-beam spatial filter as an example. Cleveland, Ohio: Lewis Research Center, 1993.

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J, Krasowski Michael, Weiland Kenneth E y United States. National Aeronautics and Space Administration. Scientific and Technical Information Program., eds. Neural-network directed alignment of optical systems using the laser-beam spatial filter as an example. [Washington, DC]: National Aeronautics and Space Administration, Office of Management, Scientific and Technical Information Program, 1993.

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P, Kaluzny S., ed. S+SpatialStats: User's manual for Windows and UNIX. New York: Springer, 1998.

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Capítulos de libros sobre el tema "Filtre spatial"

Chityala, Ravishankar y Sridevi Pudipeddi. "Spatial Filters". En Image Processing and Acquisition using Python, 61–93. Second edition. | Boca Raton : Chapman & Hall/CRC Press, 2020. | Series: Chapman & Hall/CRC the Python series: Chapman and Hall/CRC, 2020. http://dx.doi.org/10.1201/9780429243370-4.

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Bacher, C. "Ecosystem Modelling: Sensitivity of Physical Characteristics to Spatial Box Design". En Bivalve Filter Feeders, 517–18. Berlin, Heidelberg: Springer Berlin Heidelberg, 1993. http://dx.doi.org/10.1007/978-3-642-78353-1_17.

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Li, Xuan y Haixian Wang. "Smooth Spatial Filter for Common Spatial Patterns". En Neural Information Processing, 315–22. Berlin, Heidelberg: Springer Berlin Heidelberg, 2013. http://dx.doi.org/10.1007/978-3-642-42042-9_40.

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Griffith, Daniel A. y Jean H. P. Paelinck. "Spatial Filter Versus Conventional Spatial Model Specifications: Some Comparisons". En Non-standard Spatial Statistics and Spatial Econometrics, 117–49. Berlin, Heidelberg: Springer Berlin Heidelberg, 2010. http://dx.doi.org/10.1007/978-3-642-16043-1_7.

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Newell, Carter R. y Sandra E. Shumway. "Grazing of Natural Particulates by Bivalve Molluscs: A Spatial and Temporal Perspective". En Bivalve Filter Feeders, 85–148. Berlin, Heidelberg: Springer Berlin Heidelberg, 1993. http://dx.doi.org/10.1007/978-3-642-78353-1_4.

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Battisti, Michele y Gianfranco Di Vaio. "A spatially filtered mixture of β-convergence regressions for EU regions, 1980–2002". En Spatial Econometrics, 105–21. Heidelberg: Physica-Verlag HD, 2009. http://dx.doi.org/10.1007/978-3-7908-2070-6_6.

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Tang, Fuhui, Xiankai Lu, Xiaoyu Zhang, Xueqian Song, Jiyuan Cai, Hong Zhang y Jiaru Song. "Spatial Context for Correlation Filter Tracking". En Advances in Intelligent Systems and Computing, 174–81. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-98776-7_20.

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Esperança, Claudio y Hanan Samet. "Orthogonal polygons as bounding structures in filter-refine query processing strategies". En Advances in Spatial Databases, 197–220. Berlin, Heidelberg: Springer Berlin Heidelberg, 1997. http://dx.doi.org/10.1007/3-540-63238-7_31.

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Wohlleben, R., H. Mattes y Th Krichbaum. "Theory of Linear Spatial Filters". En Interferometry in Radioastronomy and Radar Techniques, 18–24. Dordrecht: Springer Netherlands, 1991. http://dx.doi.org/10.1007/978-94-011-3702-7_5.

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Umbaugh, Scott E. "Transform Filters, Spatial Filters and the Wavelet Transform". En Digital Image Processing and Analysis, 175–210. 4^a ed. Boca Raton: CRC Press, 2022. http://dx.doi.org/10.1201/9781003221142-5.

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Actas de conferencias sobre el tema "Filtre spatial"

Flannery, David, John Loomis y Mary Milkovitch. "The Use of Binary Magneto-optic Spatial Light Modulators in Pattern Recognition Processors". En Spatial Light Modulators and Applications. Washington, D.C.: Optica Publishing Group, 1988. http://dx.doi.org/10.1364/slma.1988.fa4.

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Binary magneto-optic spatial light modulators (SLM) [1] have been used successfully in several optical computing architectures. Here we concentrate on their use to implement binary phase-only filters [2-6] in coherent optical correlators including general characteristics, correlation performance, smart filters, and the potential for ternary filter encoding.

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Chumside, James H., Steen G. Hanson y Steven F. Clifford. "Optical Remote Sensing of Wind and Turbulence using Double Spatial Filtering of Scintillations". En Optical Remote Sensing of the Atmosphere. Washington, D.C.: Optica Publishing Group, 1990. http://dx.doi.org/10.1364/orsa.1990.wd2.

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Using a spatially filtered optical transmitter and a spatially filtered optical receiver, one can measure transverse wind velocity and also the strength of refractive turbulence at some localized region of the atmosphere along the propagation path from the transmitter to the receiver[1-3]. A profile of either quantity along the path can be obtained by using various combinations of filters. However, this technique requires a spatial filter on each side of the volume to be measured. For some applications, such as vertical profiling of the atmosphere, it would be desirable to place both filters at the receiver end of the path. The source could then be a natural source such as the sun or a star. In fact, this can be done.

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Solomon, J. A. y D. G. Pelli. "Spatial-frequency channels process text". En OSA Annual Meeting. Washington, D.C.: Optica Publishing Group, 1993. http://dx.doi.org/10.1364/oam.1993.wr.25.

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We measured contrast thresholds in high- and low-pass noise for identifying letters and detecting gratings. Assuming that squared contrast threshold is proportional to the total noise power passed by a single linear filter (“channel”), we calculated modulation transfer functions for the visual filters underlying the performance of each task. The filters used for letter identification and grating detection are remarkably similar.

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Javidi, B. y S. F. Odeh. "Real-time Object Recognition and Classification by Code Division Multiplexed Phase-only Encoded Filters". En Spatial Light Modulators and Applications. Washington, D.C.: Optica Publishing Group, 1988. http://dx.doi.org/10.1364/slma.1988.the13.

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A multiobject shift invariant pattern recognition system that uses Code division multiplexed binary phase-only filters is presented. The system computes the binary correlation between an input pattern with a generalized set of pattern functions. This technique uses a filter which consists of a set of binary phase-only code division multiplexed reference pattern functions. The functions in the reference set may correspond to either different objects or different variations of the object under study. In the proposed architecture, the position of the output binary correlation peaks represent the locations of the objects in the input plane. This is different from phase coded pattern recognition systems in which the location of the output peak determines the class of the input object+. Here, the system is shift invariant and multiple objects can be present at the input plane. The pattern recognition is performed without increasing the space-bandwidth product requirements of the system. Computer simulations of the architecture are also used to study the performance of the pattern recognition architecture. The signal-to-noise ratio (SNR), and the peak to the maximum correlation sidelobe ratio (P/SL) are evaluated as the criteria for the system performance.

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Dowski, Edward R. y W. Thomas Cathey. "Modern wavefront-based optical anti-aliasing filter". En International Optical Design Conference. Washington, D.C.: Optica Publishing Group, 1998. http://dx.doi.org/10.1364/iodc.1998.lfb.4.

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We have developed a completely new type of optical anti-aliasing filter that offers both high performance and low cost. In contrast to other wavefront-based anti-aliasing filters, this new filter can operate with multiple aperture stop positions. And in addition, this type of filter sufficiently attenuates all spatial frequencies beyond the CCD detector bandlimit. Many of the most popular anti-aliasing filters currently in use just null out very narrow bands of spatial frequencies.

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Dickey, F. M., B. V. K. Vijaya Kumar, L. A. Romero y J. M. Connelly. "Complex ternary matched filters yielding high signal-to-noise ratios". En OSA Annual Meeting. Washington, D.C.: Optica Publishing Group, 1989. http://dx.doi.org/10.1364/oam.1989.mff6.

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Matched spatial filters provide the highest output signal-to-noise ratio in pattern recognition applications but have not become practicable due to the complex nature of the spatial filters required. Lately much research effort has been devoted to methods of avoiding complex filters. This research has suggested binary and ternary real valued approximations to the phase-only filter. Dickey and Hansche1 suggested a quad-phase-only filter that does not suffer from having the simple symmetry of real valued filters and can have improved signal-to-noise ratio. The authors suggest a complex ternary matched filter (CTMF). This CTMF filter function has the form: where IR1 and IR2 are support functions, sr and S1 are the real and imaginary parts of the object function Fourier transform, and β is the threshold line angle. The algorithm introduced by Kumar and Bahri2 can be used to optimize this filter. The optimized CTMF produces signal-to-noise ratios very near the optimal phase-only filter and does not suffer from having the simple symmetry of real valued filters.

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Hosokawa, Shigeo, Hiroki Sakamoto y Akio Tomiyama. "Spatial Filter Velocimetry Based on Time-Series Particle Images". En ASME-JSME-KSME 2011 Joint Fluids Engineering Conference. ASMEDC, 2011. http://dx.doi.org/10.1115/ajk2011-31005.

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High spatial and temporal resolutions are required in velocity measurements for turbulent flows to examine turbulence characteristics accurately. In this study, we proposed a spatial filter velocimetry (SFV) based on a frequency analysis of time-series spatially-filtered particle images. Since this method can measure velocity from one particle in a measurement region, it enables us to measure the velocity with high spatial and temporal resolutions. We developed a SFV system and applied it to laminar and turbulent flows in a duct to examine its performance. Through comparisons between the velocities measured by SFV and LDV, we confirmed that SFV accurately measures the mean velocity and turbulent intensity with spatial and temporal resolutions as high as LDV.

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Mayers, A. W., F. T. S. Yu, S. Rajan, S. Wu y D. A. Gregory. "Colored matched spatial filters recorded in LiNbO3". En OSA Annual Meeting. Washington, D.C.: Optica Publishing Group, 1991. http://dx.doi.org/10.1364/oam.1991.thkk1.

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In many applications it is desirable to implement a correlation system capable of performing color pattern recognition. With mixed gas lasers such as the argon–krypton laser, it is possible to have a single source produce a collinear beam composed of red, green, and blue wavelengths. In this paper we investigate recording reflection and transmission matched spatial filters in photorefractive LiNbO3. We limit our discussion to simultaneous recording of the filter as opposed to sequential recording. We show that the reflection filter suffers from low diffraction efficiency as a result of grating competition, while the transmission filter suffers from wavelength crosstalk caused by grating beating. Finally, we demonstrate a transmission filter that uses a grating in the input plane to separate the wavelengths in the filter plane, and eliminate the color crosstalk.

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Ben-Haim, J. y J. Shamir. "Shift, rotation, and scale invariant pattern recognition by bipolar spatial filtering". En OSA Annual Meeting. Washington, D.C.: Optica Publishing Group, 1986. http://dx.doi.org/10.1364/oam.1986.the3.

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The objective of this work is to identify an object out of a given set of objects. Shift invariance is automatically achieved by employing spatial filters in the Fourier transform plane. To relax the strict alignment and stability requirements of the holographic filter, we use bipolar amplitude filters with minimum information content that is still sufficient for the required pattern recognition. For complete rotation invariance one may use filters with rotation symmetry, while for scale invariance, filters that are independent on the radial coordinate may be employed. Partial invariances combined in a single filter are also investigated. Theoretical considerations augmented with computer simulation are used for the determination of acceptable recognition criteria and for the synthesis of practical filters. The feasibility of the method was demonstrated by computer simulations and some preliminary experiments.

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Town, Graham E. "Application of digital-filter theory to the design of grating filters". En OSA Annual Meeting. Washington, D.C.: Optica Publishing Group, 1993. http://dx.doi.org/10.1364/oam.1993.thvv.3.

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Inverse scattering methods may be used to design coupled mode waveguide filters with either codirectional or contradirectional coupling.1 The response of these and other spatially periodic waveguiding structures is periodic in the frequency domain, a property also exhibited by digital filters. A fundamental problem in digital filter design is to closely approximate the response of a continuous system. In most cases exact replication is impossible, unless an infinite sampling frequency is used, and large amounts of memory are available. Similar problems arise in the design of corrugated waveguide filters, and are associated with finite frequency of the spatial periodicity, and finite coupling lengths. The approximation problem becomes significant when the desired waveguide filter bandwidth is comparable to the optical carrier frequency, a situation which arises when large coupling coefficients are involved, or the coupling region is short. In such situations, significant distortion of the desired spectral response can occur unless the periodicity of the spectral response is accounted for in the design process. Suitable approximation methods from digital filter theory will be shown to improve the performance of coupled mode filters designed by inverse scattering methods.

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Informes sobre el tema "Filtre spatial"

Kallman, Robert R. Optical Spatial Filter Development. Fort Belvoir, VA: Defense Technical Information Center, junio de 1995. http://dx.doi.org/10.21236/ada301435.

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Mansour, N. A. Computer realization of spatial filters. Natural Resources Canada/ESS/Scientific and Technical Publishing Services, 1986. http://dx.doi.org/10.4095/304876.

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Kovalenkov, A. N., S. M. Semchenkov y M. S. Makarov. Spatial inverse filtering method based on a controlled structure filter. OFERNIO, noviembre de 2020. http://dx.doi.org/10.12731/ofernio.2020.24671.

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Williams, J., T. Beavers, S. Bryan, G. Hermes y H. Patton. NIF Inert Gas/Vacuum Management Prestart Review Phase 3 - Permit Spatial Filter Vacuum. Office of Scientific and Technical Information (OSTI), marzo de 2001. http://dx.doi.org/10.2172/15013286.

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Herman, Martin y Rama Chellappa. A general motion model and spatio-temporal filters for computing optical flow. Gaithersburg, MD: National Institute of Standards and Technology, 1994. http://dx.doi.org/10.6028/nist.ir.5539.

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Beal, Samuel y Matthew Bigl. Particle size characteristics of energetic materials distributed from low-order functioning mortar munitions. Engineer Research and Development Center (U.S.), agosto de 2024. http://dx.doi.org/10.21079/11681/49189.

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Particles of explosive filler distributed from low-order (LO) munition functioning are susceptible to dissolution and potential mobilization into groundwater and surface water. We command-initiated three mortar munitions as LO in triplicate using a fuze simulator and recovered particles from an ice surface to constrain LO particle characteristics. Total explosive mass recovery (19–55%) and spatial distribution (0->20 m) varied significantly both between munitions and between replicate LOs of the same munition. The median particle size (0.27–3.99 mm) varied with total mass recovery. In general, LO particles coarsened, and total mass deposition rates decreased logarithmically, with increasing distance from the initiation point.

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Liu, Hongche. A general motion model and spatio-temporal filters for 3-D motion interpretations. Gaithersburg, MD: National Institute of Standards and Technology, 1995. http://dx.doi.org/10.6028/nist.ir.5763.

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Sinclair, Samantha y Sally Shoop. Automated detection of austere entry landing zones : a “GRAIL Tools” validation assessment. Engineer Research and Development Center (U.S.), agosto de 2022. http://dx.doi.org/10.21079/11681/45265.

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The Geospatial Remote Assessment for Ingress Locations (GRAIL) Tools software is a geospatial product developed to locate austere entry landing zones (LZs) for military aircraft. Using spatial datasets like land classification and slope, along with predefined LZ geometry specifications, GRAIL Tools generates binary suitability filters that distinguish between suitable and unsuitable terrain. GRAIL Tools combines input suitability filters, searches for LZs at user‐defined orientations, and plots results. To refine GRAIL Tools, we: (a) verified software output; (b) conducted validation assessments using five unpaved LZ sites; and (c) assessed input dataset resolution on outcomes using 30 and 1‐m datasets. The software was verified and validated in California and the Baltics, and all five LZs were correctly identified in either the 30 or the 1‐m data. The 30‐m data provided numerous LZs for consideration, while the 1‐m data highlighted hazardous conditions undetected in the 30‐m data. Digital elevation model grid size affected results, as 1‐m data produced overestimated slope values. Resampling the data to 5 m resulted in more realistic slopes. Results indicate GRAIL Tools is an asset the military can use to rapidly assess terrain conditions.

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Farahbod, A. y J. F. Cassidy. Spatial and temporal variations in seismic coda Q attenuation in the lower St. Lawrence region, southeastern Quebec. Natural Resources Canada/CMSS/Information Management, 2023. http://dx.doi.org/10.4095/332027.

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We investigate seismic attenuation characteristics of the Lower St. Lawrence seismic zone in southeastern Quebec. This zone is located ~400 km downstream from Quebec City and is between the Quebec North Shore and the Lower St. Lawrence. We used earthquake recordings from 5 broadband and 5 short period seismograph stations of the Canadian National Seismic Network (CNSN) across the region. Our dataset is comprised of 847 earthquakes recorded between 1985 and 2022 with magnitudes ranging from 2.0 to 5.1, depths from 0 to 30 km and epicentral distances of 5 to 100 km. This gives a total of 446 high signal-to-noise (S/N) traces (S/N?5.0) useful for QC calculation (with a maximum ellipse parameter, a2, of 100) across the region. Coda windows were selected to start at tc = 2tS (two times the travel time of the direct S wave), and were filtered at center frequencies of 2, 4, 8, 12 and 16 Hz. Our study reveals a consistent pattern. We find that the lowest overall average of Q0 (Q at 1 Hz) values are at the three stations (GSQ, ICQ and SMQ) within 100 km of a moderate earthquake of mN 5.1 in 1999 (e.g., Q0 of 81, 88 and 80, respectively). We determined temporal variations in attenuation following the 1999 earthquake. The overall average of Q0 decreased from 87 (before the mainshock) to 77 (GSQ, D=96 km), from 92 to 85 (ICQ, D=69 km) and from 88 to 82 (SMQ, D=73 km). These results are in agreement with global studies that show a decrease in Q0 following a significant earthquake, (e.g., M &gt; 5) likely the result of increased fracturing and fluids in the epicentral region. An average for all the data results in a Q relationship of QC = 86f1.07 for the frequency band of 2 to 16 Hz for the entire region.

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Lamontagne, M. Macroseismic information for the 1935 moment magnitude 6.1 earthquake, near Témiscamingue, Quebec. Natural Resources Canada/CMSS/Information Management, 2021. http://dx.doi.org/10.4095/329136.

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The November 1st, 1935, Témiscaming earthquake occurred within 20 km of the town of Témiscaming, Quebec. This earthquake was felt west to Fort William (now part of Thunder Bay), Ontario, east to Saint John, New Brunswick, and south to Kentucky and Virginia. Damaged chimneys were reported in Témiscaming, Quebec, and North Bay and Mattawa, Ontario. In the epicentral region, rockfalls were observed as well as cracks in gravel and sand along the shores of islands and lakes. Some 350 km away from the epicentre, near Parent, Quebec, earthquake vibrations triggered a 30 metre slide of railroad embankment. Numerous aftershocks were felt in Témiscaming and Kipawa during the following months, the largest rated as magnitude ML 5.4 (or mN 4.9). For the main shock and its largest aftershock, this Open File Report provides the available macroseismic information interpreted on the Modified Mercalli Intensity Scale using newspaper accounts as the main source of information for Canada. Macroseismic information from total of 126 localities in Canada and nearly 900 communities in the US (from the NOAA database of intensities) are tabulated in a Microsoft Excel spreadsheet. When available, newspaper clippings are included, together with some original damage accounts, photographs and scientific reports. The Open File also includes a Google Earth kmz file that allows the felt information reports to be viewed in a spatial tool.

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