• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 11
  • 8
  • 6
  • 6
  • 2
  • 1
  • Tagged with
  • 36
  • 8
  • 7
  • 6
  • 5
  • 5
  • 4
  • 4
  • 4
  • 4
  • 4
  • 4
  • 3
  • 3
  • 3
  • 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.
1

Development of a Prediction Model for Skid Resistance of Asphalt Pavements

Rezaei, Arash 2010 December 1900 (has links)
The skid resistance of asphalt pavement is a major characteristic that determines the driving safety on a road, especially under wet surface conditions. Skid resistance is primarily a function of the microtexture and macrotexture of a pavement surface. Microtexture is influenced by aggregate surface characteristics and is required to disrupt the continuity of surface water film and attain frictional resistance between the tire and the pavement surface. Macrotexture is affected mostly by mixture design or aggregate gradation and contributes to skid resistance by providing drainage paths of water that can be otherwise trapped between a tire and a pavement surface. The increase in macrotexture contributes to preventing hydroplaning and improving wet frictional resistance, particularly at high speeds. While much research has been conducted in the past to identify material factors that affect skid resistance, there is still a need to develop a model for predicting asphalt pavement skid resistance as a function of mixture characteristics and traffic level. The purpose of this study was to develop such a model based on extensive laboratory experiments and field measurements involving different mixture types and aggregate sources. The model incorporates functions that describe the resistance of aggregates to polishing and aggregate size distribution. The aggregate resistance to polishing was quantified by measuring aggregate texture using the Aggregate Imaging System (AIMS) before and after polishing in the Micro-Deval device. The analysis in this dissertation demonstrates how this model can be used to design mixtures and classify aggregates that provide desirable skid resistance levels.
2

Problematika střídání kmenových souhlásek ve finštině jako druhém jazyce / Problems of consonant gradation in Finnish as a second language

Kahounová, Petra January 2012 (has links)
Author's name: Petra Kahounová School: Charles University, Prague, Faculty of Arts Institute of Linguistics and Finno-Ugric Studies Náměstí Jana Palacha 2, 116 38 Praha 1 Program: Finnish language Title: Problems of consonant gradation in Finnish as a second language Consultant: Mgr. Lenka Fárová, Ph.D. Number of pages: 65 + 11 pages of attachments Number of attachments: 5 Year: 2012 Keywords: gradation of consonants in Finnish, corpus, analysis of mistakes, direct gradation, reverse gradation, student's language The aim of this thesis is to explore and describe mistakes made in the consonant gradation in interlanguage by students of Finnish language. Finnish has a complicated system of inflection in comparison with indoeuropean languages, so it is necessary to know the rules to create the right form of the word. The mistakes were found in czech and polish students' texts and I tried to identify in which types of gradation they are most frequent. Particular mistakes were sorted into groups according to types of consonant clusters. I compared what mistakes czech and polish students make, which mistakes are the most frequent and if there are some any similarities between these two nations. I focused on explanation of wrong word forms.
3

AvaliaÃÃo da influÃncia da granulometria na aderÃncia pneu-pavimento / Granulometry influence the evaluation in tire-pavement adherence

Amanda Cavalcante Rodrigues 08 November 2013 (has links)
Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico / Uma dificuldade que acomete as empresas de construÃÃo pesada em relaÃÃo à seguranÃa viÃria à atingir valores mÃnimos de aderÃncia exigidos em campo para o revestimento de pavimentos. Valores mÃnimos de microtextura, ensaiados atravÃs do pÃndulo britÃnico, e faixas de macrotextura, ensaiadas pelo ensaio de mancha de areia, sÃo encontrados no Manual de RestauraÃÃo de Pavimentos AsfÃlticos do DNIT de 2006. Nas situaÃÃes onde esses parÃmetros ligados à aderÃncia sÃo controlados, o revestimento precisa ser reexecutado quando a micro e a macrotextura nÃo se aproximam do exigido pelas normas. Trata-se de um problema apenas observado durante a fase de construÃÃo, uma vez que nÃo se determina a aderÃncia em laboratÃrio, na fase de projeto. Pesquisas apontam que as mudanÃas nas propriedades dos agregados e na granulometria podem afetar a micro e a macrotextura da camada de rolamento. A fim de contribuir na questÃo da aderÃncia, buscando a previsÃo desse parÃmetro ainda indiretamente em laboratÃrio, objetivou-se desenvolver uma metodologia capaz de testar granulometrias para verificar o efeito das fraÃÃes dos materiais das peneiras nesta aderÃncia da superfÃcie do pavimento. A metodologia proposta consistiu em comparar a textura da massa asfÃltica compactada em campo e em laboratÃrio utilizando os ensaios de mancha de areia e de pÃndulo britÃnico. Objetivou-se, ainda, desenvolver um modelo capaz de predizer o valor de macrotextura da camada de rolamento atravÃs de granulometrias das misturas asfÃlticas estudadas. O modelo foi composto por dados de fraÃÃes retidas entre as peneiras nÂ40 e 3/8â. Os principais resultados obtidos levaram à conclusÃo de que a metodologia desenvolvida em laboratÃrio foi consistente no aspecto de microtextura entre campo e laboratÃrio. Em relaÃÃo ao modelo, houve uma correlaÃÃo considerada satisfatÃria, portanto, indicando o potencial da previsÃo da macrotextura ainda na fase de projeto a partir da granulometria a adotar. / A difficulty that affects pavement contractors regarding road safety is to achieve minimum values of surface friction required to the pavement in the field. Minimum values of microtexture tested through the British pendulum and ranges of macrotexture tested by the sand patch test are found in the DNIT Manual of Asphalt Pavements Restoration (2006). In situations where the friction parameters are controlled, oftentimes the pavement needs to be reexecuted when the micro and macrotexture do not meet the required values. This is a problem only observed during the construction phase as friction is not determined indirectly in the laboratory during the design phase. Research indicates that changes in the properties of the aggregates and the particle size can affect the microtexture and macrotexture of the surface course. In order to contribute to the topic of friction, seeking the prediction of this parameter in the laboratory, this work aimed to develop a methodology capable of evaluating gradations and the effect of the sieve fractions of materials in the of pavement surface friction. The proposed methodology consisted in comparing the texture of the asphalt mixture compacted in laboratory, and field tests using sand patch and British pendulum. It also aimed to develop a model to predict the value of macrotexture of the surface course through the gradation of the asphalt mixtures studied. The model was composed by data of retained fractions in sieve #40 to 3/8". The main results obtained led to the conclusion that the methodology developed in the laboratory was consistent in the aspect of microtexture between field and laboratory. Regarding the model, there was a satisfactory correlation, indicating the potential of predicting macrotexture in the design phase from the mixture gradation.
4

Vliv kůrovcové gradace na rozšíření a potravní ekologii datlíka tříprstého (Picoides tridactylus) v Národním parku Šumava / The impact of a bark beetle gradation on the occurrence and feeding ecology of a three-toed woodpecker (Picoides tridactylus) in the Šumava National Park

Navrátil, Martin January 2014 (has links)
The main objective of this study was to find factors that influence the occurrence of three-toed woodpecker (Picoides tridactylus) in Šumava at a time when the bark beetle gradation caused by Kyrill subside. The research was conducted on five transects. To prove the presence of three-toed woodpecker was opted the method of an acoustic provocation, which reliability was well proven. The hypothesis was that the three-toed woodpecker prefers the trees infested by bark beetle instead of healthy trees. Surprisingly, however, he also prefered the stands where the main attack took place several years ago. Regardless of their health status the tree- toed woodpecker preferred non-intervention stands instead of the on- going management forest. Among other factors, the exposure was applied (preferred south and west) and elevation (median, minimum altitude of about 1100 m.). Another important result is that Picoides tridactylus prefers for its food stands still alive or just dead spruce trees infested by the bark beetle. Overall, it appears that the three-toed species has narrowly defined biotope demands, which are linked to the natural spruce forest unaffected by people. The results of this study could be used to better understanding of the ecology three-toed woodpecker, eventually can help to create a...
5

A gradação nas obras de György Ligeti dos anos sessenta

Claudio Horacio Vitale 07 May 2013 (has links)
Esta tese tem por objetivo estudar as obras do compositor György Ligeti dos anos sessenta a através do conceito de gradação. Em termos gerais, as obras desses anos são construídas a partir da harmonia do cluster e da superposição de diferentes estruturas rítmicas. A ideia de gradação é elaborada tomando como base conhecimentos provenientes de diversas áreas tais como a retórica, a literatura, a filosofia, a linguística, as artes visuais e a música. No que diz respeito à análise das obras de Ligeti estudam-se aspectos como: a superposição de diferentes divisões do tempo, as relações entre ritmo e textura e os vínculos entre gradação superpostas. Obras como Atmosphères e o Quarteto de Cordas nº 2 são estudadas com maior detalhamento em função de conceitos como gradação, continuum e desvio. A partir dos diferentes estudos conclui-se que a ideia de gradação, entendida como uma ordenação que aumenta ou diminui progressivamente em relação a uma qualidade ou propriedade, constitui o fundamento das obras escritas por Ligeti nos anos sessenta. Esta noção funciona tanto no nível do procedimento como do próprio pensamento composicional. / The goal of this thesis is to study the works of György Ligeti composed in the sixties, taking as principal idea for this analysis the concept of gradation. In general terms, the works of these years were composed taking into account the cluster harmony and the superposition of different rhythmic structures. The idea of gradation is based on concepts taken from different areas such as rhetoric, literature, philosophy, linguistics, visual arts and music. In the analysis of the works of Ligeti we study several aspects such as: superposition of different divisions of time, relationship between rhythm and texture and connections between overlaid gradation processes. The compositions Atmosph` eres and String Quartet nº 2 are studied in more detail taking into account the concepts of gradation, continuum and deviation. Based on these different studies we conclude that the idea of gradation, understood as an order of things that grows or diminishes progressively with respect to a quality or property, constitutes the basis of the works written by Ligeti in the sixties. This notion is appropriate both at the level of procedure and at the proper compositional thinking.
6

A gradação nas obras de György Ligeti dos anos sessenta

Vitale, Claudio Horacio 07 May 2013 (has links)
Esta tese tem por objetivo estudar as obras do compositor György Ligeti dos anos sessenta a através do conceito de gradação. Em termos gerais, as obras desses anos são construídas a partir da harmonia do cluster e da superposição de diferentes estruturas rítmicas. A ideia de gradação é elaborada tomando como base conhecimentos provenientes de diversas áreas tais como a retórica, a literatura, a filosofia, a linguística, as artes visuais e a música. No que diz respeito à análise das obras de Ligeti estudam-se aspectos como: a superposição de diferentes divisões do tempo, as relações entre ritmo e textura e os vínculos entre gradação superpostas. Obras como Atmosphères e o Quarteto de Cordas nº 2 são estudadas com maior detalhamento em função de conceitos como gradação, continuum e desvio. A partir dos diferentes estudos conclui-se que a ideia de gradação, entendida como uma ordenação que aumenta ou diminui progressivamente em relação a uma qualidade ou propriedade, constitui o fundamento das obras escritas por Ligeti nos anos sessenta. Esta noção funciona tanto no nível do procedimento como do próprio pensamento composicional. / The goal of this thesis is to study the works of György Ligeti composed in the sixties, taking as principal idea for this analysis the concept of gradation. In general terms, the works of these years were composed taking into account the cluster harmony and the superposition of different rhythmic structures. The idea of gradation is based on concepts taken from different areas such as rhetoric, literature, philosophy, linguistics, visual arts and music. In the analysis of the works of Ligeti we study several aspects such as: superposition of different divisions of time, relationship between rhythm and texture and connections between overlaid gradation processes. The compositions Atmosph` eres and String Quartet nº 2 are studied in more detail taking into account the concepts of gradation, continuum and deviation. Based on these different studies we conclude that the idea of gradation, understood as an order of things that grows or diminishes progressively with respect to a quality or property, constitutes the basis of the works written by Ligeti in the sixties. This notion is appropriate both at the level of procedure and at the proper compositional thinking.
7

Analyse de formes et de textures : application à l'authentification et à la gradation de pièces de monnaies / Shape and texture analysis : application to coin identification and coin grading

Pan, Xingyu 05 June 2018 (has links)
Objets de collection depuis les temps anciens, de nos jours les pièces de monnaie constituent un marché de plus en plus important. L’évaluation par des experts de l’état de conservation des pièces de monnaie, que nous nommons gradation, joue un rôle important pour déterminer leur valeur sur le marché. Dans le but de grader des pièces de monnaie de manière efficace et objective, la société GENI collabore avec le laboratoire LIRIS, afin d’automatiser le processus de gradation à partir de photos de pièces de monnaie.L’objectif principal de cette thèse est de fournir une aide à la gradation des pièces de monnaie à partir des photos de qualité. Le projet est composé de quatre phases : segmentation des monnaies, identification du type monétaire, détection et reconnaissance du millésime et gradation des monnaies.Dans la première phase, la pièce de monnaie est segmentée de sa photo de manière précise à l’aide d’un modèle paramétrique déformable. Ce dernier permet également d’extraire des caractéristiques de la pièce de monnaie telles que sa taille, son nombre de coins, de pans, etc.Lors de la deuxième phase, nous cherchons dans une base de données le type monétaire de référence correspondant à la pièce de monnaie requête à l’aide de scores de similarité basés sur des graphes. Le premier score se base sur des caractéristiques locales des contours en relief, et le second, qui est semi-global, permet de mettre en évidence des différences de motifs.La troisième phase concerne la reconnaissance du millésime. Il s’agit d’un sujet difficile car les caractères, dans ce contexte, ont un premier plan de couleur très similaire à l’arrière-plan. Après avoir localisé la zone du millésime et l’avoir découpée en imagettes de chiffres, nous proposons une méthode de reconnaissance de chiffres à l’aide de caractéristiques « topologiques ».Enfin, concernant la gradation des monnaies, nous proposons une méthode se basant sur une quantification des « éléments inattendus » comme les rayures et les taches. La pièce de monnaie est d’abord recalée sur une monnaie de référence, puis, nous détectons les « éléments inattendus » significatifs sur des zones d’intérêt. Enfin, concernant les « éléments inattendus » ténus difficiles à repérer individuellement, nous détectons les zones granuleuses à l’aide du Deep Learning. Le résultat obtenu par cette méthode, proche de ce que l’expert réalise « à la main », servira d’aide aux numismates. / Coins have been collected and studied since ancient times. Today, coin collection has become a hobby for anyone who wants to participate in. Coin grading is a way of determining the physical condition of a coin to provide an indicator for its market value. For grading coins on a large scale and in a relatively objective way, the GENI company cooperates with the laboratory LIRIS to automate the process by using coin photos.The main objective of this thesis is to grade coins from well-conditioned photos. The project is composed of four steps: coin segmentation from raw photos, monetary type identification, coin date detection and recognition and, coin grading.The first step is to extract coins from raw photos with a high precision. With a deformable geometric model, we segment precisely round coins, many-sided coins, wavy edged coins and holed coins by recognizing their shapes.The second step consists of coin recognition or monetary type identification. We match the query coin to the most identical type reference by using two similarity scores. The first similarity score is based on local features of relief contours. The second similarity score is a semi-global measure that highlights the difference between relief patterns.The third step is to detect and recognize coin dates. However, the fact that such characters have the same color as the background makes traditional optical character recognition methods difficult to apply. After extracting the date zone and cropping it into digit images, we propose a learning-free method to recognize those digits by analyzing their “topological” features.In the last step, the grading process is carried out by quantification of "unexpected elements" such as scratches and dirty marks. The coin to grade is registered to a reference coin. Then, large “unexpected elements” are detected in some regions of interest. However, some “micro-scratches” are difficult to extract individually but all together make a "grainy" surface. To deal with it, we use Deep Learning techniques to classify those grainy zones containing such “micro-scratches”. The result of our system, which is close to the manual expert one, is considered as a useful help for numismatists.
8

Ad hoc stupňování "nestupňovatelných" adjektiv v češtině / Ad hoc gradation of "non-gradable" adjectives in Czech

Doischer, Tomáš January 2017 (has links)
There are some adjectives in language which sound strange to a native speaker in their graded form. Consider this sentence: "These pearls are more real than the real ones!" ("Tyhle perly jsou pravější než pravé!") How can they be more real? What does it even mean? I attempt to answer these and other questions in this paper. While the phenomenon of rarely graded adjectives may quite peripheral, it is nonetheless interesting and understanding it is important for the general understanding of adjective gradation. Adjectives such as real are traditionally considered non-gradable. However, as we can see from the example, that doesn't mean they can't be graded. The distinction between gradable and non-gradable adjectives apparently cannot be clear-cut. The goal of this paper is to describe this phenomenon, determine which properties rarely graded adjectives have and how they can be graded. I use data from a large corpus of written Czech (SYN v4) to find these adjectives and the way they are used. I employ both quantitative and qualitative methods to reach a comprehensive overview of rarely graded adjectives. I use statistical methods to find parameters specific for this type of adjective and semantic analysis to divide it into well-motivated categories. I also explain why they are graded only rarely, how...
9

Gradation-Based Framework for Asphalt Mixtures

Lira Miranda, Bernardita Francisca January 2012 (has links)
Asphalt mixture microstructure is formed by aggregates, bitumen binder and air voids. Aggregates make for up to 90% of the mixtures volume and the structure formed by them will depend mostly on their size distribution and shape. The study presented in this thesis has as main objective to develop a framework that allows the characterization of asphalt mixtures based on the aggregates gradation and its impact on pavement performance. Moreover, the study aims to identify the range of aggregate sizes which form the load carrying structure, called Primary Structure, and determine its quality. The method has been developed as a numerical procedure based on packing theory of spheres. Parameters like porosity, coordination number and disruption factor of the Primary Structure; and a binder distribution parameter for the different sub-structures have been used to evaluate the quality of the load carrying structure and predict the impact on several failure modes. The distribution of bitumen binder has been derived from a geometrical model which relates porosity of the mixture with film thickness of particles considering the overlapping reduction as the film grows. The model obtained is a closer approximation to a physical characteristic of the compacted mixture separated according to different elements of the structure. The framework has been evaluated on several field and laboratory mixtures and predictions have been made about their rutting performance and moisture resistance. The calculated parameters have compared favourably with the performances reported from the field and laboratory testing. The developed gradation analysis framework has proven to be a tool to identify those mixtures with a poor rutting performance based on the gradation of the aggregates. The Gradation - Based Framework has satisfactory distinguished between good and bad performance of asphalt mixtures when related to permanent deformation and moisture damage. The calculated parameters have allowed identifying and understanding the main mechanisms and variables involved in permanent deformation and moisture damage of asphalt mixtures. The developed model can be used as a tool to determine the optimal gradation to assure good performance for hot mix asphalt pavements. / QC 20120626
10

Survey of railway ballast selection and aspects of modelling techniques

Yitayew Alemu, Abateneh January 2011 (has links)
Previously great attention has been given for the quality of the track super structure to improve the overall performance of the railway. Frequent research on the track supporting materials shows a good result which improves the existing overall performance. Good ride quality with high speed, minimum initial construction capital, long life service and low maintenance cost are the issue on the railway technology. Ballast is one of the determinant parts of the railway structure which has great influence on the performance of the railway track. The aim of this project is to assess the different aspects which affect the overall performance on the ballast structure, its material characterization, gradation, failure modes and modelling techniques. Quality based ballast material characteristics investigation and proper selection of ballast gradation with proper modelling methods will lead to an economical, minimum defect, minimum maintenance and replacement cost.

Page generated in 0.0872 seconds