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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
41

Towards spectral mathematical morphology / Vers la morphologie mathématique spectrale

Deborah, Hilda 21 December 2016 (has links)
En fournissant en plus de l'information spatiale une mesure spectrale en fonction des longueurs d'ondes, l'imagerie hyperspectrale s'enorgueillie d'atteindre une précision bien plus importante que l'imagerie couleur. Grâce à cela, elle a été utilisée en contrôle qualité, inspection de matériaux,… Cependant, pour exploiter pleinement ce potentiel, il est important de traiter la donnée spectrale comme une mesure, d'où la nécessité de la métrologie, pour laquelle exactitude, incertitude et biais doivent être maitrisés à tous les niveaux de traitement.Face à cet objectif, nous avons choisi de développer une approche non-linéaire, basée sur la morphologie mathématique et de l'étendre au domaine spectral par le biais d'une relation d'ordre spectral basée sur les fonctions de distance. Une nouvelle fonction de distance spectrale et une nouvelle relation d'ordonnancement sont ainsi proposées. De plus, un nouvel outil d'analyse du basé sur les histogrammes de différences spectrales a été développé.Afin d'assurer la validité des opérateurs, une validation théorique rigoureuse et une évaluation métrologique ont été mises en œuvre à chaque étage de développement. Des protocoles d'évaluation de la qualité des traitements morphologiques sont proposés, exploitant des jeux de données artificielles pour la validation théorique, des ensembles de données dont certaines caractéristiques sont connues pour évaluer la robustesse et la stabilité et des jeux de données de cas réel pour prouver l'intérêt des approches en contexte applicatif. Les applications sont développées dans le contexte du patrimoine culturel pour l'analyse de peintures et pigments. / Providing not only spatial information but also spectral measure as a function of wavelength, hyperspectral imaging boasts a much greater gain in accuracy than the traditional color imaging. And for this capability, hyperspectral imaging has been employed for quality control, inspection of materials in various fields. However, to fully exploit this potential, it is important to process the spectral data as a measure. This induces the need of metrology where accuracy, uncertainty, and bias are managed at every level of processing.Aiming at developing a metrological image processing framework for spectral data, we select to develop a nonlinear approach using the mathematical morphology framework and extended it to the spectral domain by means of a distance-based ordering relation. A novel spectral distance function and spectral ordering relation are proposed, in addition of a new analysis tools based on spectral differences. To ensure the validity of the spectral mathematical morphology framework, rigorous theoretical validation and metrological assessment are carried out at each development stages. So, protocols for quality assessment of spectral image processing tools are developed. These protocols consist of artificial datasets to validate completely the theoretical requirements, datasets with known characteristics to assess the robustness and stability, and datasets from real cases to proof the usefulness of the framework on applicative context. The application tasks themselves are within the cultural heritage domain, where the target images come from pigments and paintings. / Hyperspektral avbildning muliggjør mye mer nøyaktige målinger enn tradisjonelle gråskala og fargebilder, gjennom både høy romlig og spektral oppløsning (funksjon av bølgelengde). På grunn av dette har hyperspektral avbildning blitt anvendt i økende grad ulike applikasjoner som kvalitetskontroll og inspeksjon av materialer. Men for å fullt ut utnytte sitt potensiale, er det viktig å være i stand til å behandle spektrale bildedata som målinger på en gyldig måte. Dette induserer behovet for metrologi, der nøyaktighet, usikkerhet og skjevhet blir adressert og kontrollert på alle nivå av bildebehandlingen.Med sikte på å utvikle et metrologisk rammeverk for spektral bildebehandling valgte vi en ikke-lineær metodikk basert på det etablerte matematisk morfologi-rammeverket. Vi har utvidet dette rammeverket til det spektrale domenet ved hjelp av en avstandsbasert sorteringsrelasjon. En ny spektral avstandsfunksjon og nye spektrale sorteringsrelasjoner ble foreslått, samt nye verktøy for spektral bildeanalyse basert på histogrammer av spektrale forskjeller.For å sikre gyldigheten av det nye spektrale rammeverket for matematisk morfologi, har vi utført en grundig teoretisk validering og metrologisk vurde-ring på hvert trinn i utviklingen. Dermed er og-så nye protokoller for kvalitetsvurdering av spektrale bildebehandlingsverktøy utviklet. Disse protokollene består av kunstige datasett for å validere de teoretiske måletekniske kravene, bildedatasett med kjente egenskaper for å vurdere robustheten og stabiliteten, og datasett fra reelle anvendelser for å bevise nytten av rammeverket i en anvendt sammenheng. De valgte anvendelsene er innenfor kulturminnefeltet, hvor de analyserte bildene er av pigmenter og malerier.
42

Technical efficiency, technical change and return to scale of rice, maize and agricultural production in Vietnam

Tran, Duc Tri 25 April 2019 (has links)
No description available.
43

An apt perspective of analysis

Kishore, Nanad, Chandra, Ramesh 02 May 2012 (has links)
The discourse presented here is aimed at examining the justification of applications of current analysis to real world problems.
44

Non-response error in surveys

Taljaard, Monica 06 1900 (has links)
Non-response is an error common to most surveys. In this dissertation, the error of non-response is described in terms of its sources and its contribution to the Mean Square Error of survey estimates. Various response and completion rates are defined. Techniques are examined that can be used to identify the extent of nonresponse bias in surveys. Methods to identify auxiliary variables for use in nonresponse adjustment procedures are described. Strategies for dealing with nonresponse are classified into two types, namely preventive strategies and post hoc adjustments of data. Preventive strategies discussed include the use of call-backs and follow-ups and the selection of a probability sub-sample of non-respondents for intensive follow-ups. Post hoc adjustments discussed include population and sample weighting adjustments and raking ratio estimation to compensate for unit non-response as well as various imputation methods to compensate for item non-response. / Mathematical Sciences / M. Com. (Statistics)
45

Non-response error in surveys

Taljaard, Monica 06 1900 (has links)
Non-response is an error common to most surveys. In this dissertation, the error of non-response is described in terms of its sources and its contribution to the Mean Square Error of survey estimates. Various response and completion rates are defined. Techniques are examined that can be used to identify the extent of nonresponse bias in surveys. Methods to identify auxiliary variables for use in nonresponse adjustment procedures are described. Strategies for dealing with nonresponse are classified into two types, namely preventive strategies and post hoc adjustments of data. Preventive strategies discussed include the use of call-backs and follow-ups and the selection of a probability sub-sample of non-respondents for intensive follow-ups. Post hoc adjustments discussed include population and sample weighting adjustments and raking ratio estimation to compensate for unit non-response as well as various imputation methods to compensate for item non-response. / Mathematical Sciences / M. Com. (Statistics)
46

使用方向距離函數探討我國銀行業技術效率 —非貝氏方法考慮函數的單調與曲度性質 / Technical Efficiency of Commercial Banks in Taiwan on Directional Distance Function - A Non-Bayesian Approach Imposing Monotonicity and Curvature Conditions

毛芝瑩, Mao, Chih Ying Unknown Date (has links)
本研究發展新的計量方法,運用隨機邊界法將單調性和曲度條件等性質納入迴歸模型,使用聯立迴歸模型進行估計,藉此讓係數估計值不易出現違反經濟理論的情況。 採用台灣2002年至2015年,51家商業銀行進行實證分析,發現本研究方法估計產出方向距離函數時,僅有5%以下的樣本點不符合單調和曲度等性質,用於估計產出面距離函數時,僅有2%以下的樣本點不符合。進一步探討台灣銀行業之非意欲產出--逾期放款--對估計技術效率的影響,顯示不考慮此非意欲產出造成整體銀行業、非金控本國銀行與外商銀行的技術效率被高估,而金控本國銀行的技術效率則被低估,此外,分析2007年金融風暴前後銀行業經營效率變化,顯示考慮非意欲產出銀行業經營效率顯著提升,然而,未考慮非意欲產出銀行業經營效率卻下降,兩者結果有著極大的差異。 / The aim of the paper is to develop a new approach, which is stochastic frontier analysis imposing monotonicity and curvature conditions, then using simultaneous regression model to estimate. By the approach, it can solve the problem of most of the coefficient estimates violating the economic theory. The study uses the data of 51 commercial banks in Taiwan from 2002 to 2015 to conduct the empirical analysis. It indicates that by output directional distance function, less than 5% sample points violate the monotonicity and curvature conditions; by output distance function, less than 2% sample points don’t obey the restricted conditions. Further, the paper discusses the effect of commercial banks’ undesirable output- non-performing loan- on estimating technical efficiency. The results show that ignoring the undesirable output cause the technical efficiency of overall banks, non-finance holding banks and foreign banks are overvalued, and the technical efficiency of finance holding banks are undervalued. Furthermore, analyze the change of business efficiency after financial crisis in 2007. It points out that using the model consider the undesirable output, the banks’ efficiency rises. However, using the model no consider the undesirable output, the banks’ efficiency decreases. There is an extremely conflict between two approach.
47

Převod trojúhelníkových polygonálních 3D sítí na 3D spline plochy / 3D Triangles Polygonal Mesh Conversion on 3D Spline Surfaces

Jahn, Zdeněk Unknown Date (has links)
In computer graphics we can handle unstructured triangular 3D meshes which are not too usable for processing through their irregularity. In these situations it occurs need of conversion that 3D mesh to more suitable representation. Some kind of 3D spline surface can be proper alternative because it institutes regularity in the form of control points grid and that's why it is more suitable for next processing. During conversion, which is described in this thesis, quadrilateral 3D mesh is constructed at first. This mesh has regular structure but mainly the structure corresponds to structure of control points grid of resulting 3D spline surface. Created quadrilateral 3D mesh can be saved and consequently used in specific modeling applications for T-spline surface creation.

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