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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.
21

Alternative Test Methods for Evaluating Fly Ash for use in Concrete

de Groot, Andre Pieter 23 August 2011 (has links)
Fly Ash was tested in relation to its ability to mitigate alkali-silica reaction, its contribution to strength, electrical resistance and heat release with the aim of recommending improvements to fly ash specifications. ASTM C 1567 accelerated mortar bar test results were in agreement with an expansion limit of 0.10 % at 14 days. A non-standard alkali leaching test showed that with high alkali fly ashes as replacement level increases the amount of alkalis leached increases while prism expansions decrease. Measures of pozzolanic activity can be improved by measuring against non-pozzolanic fillers, This requires high replacement levels to reduce statistical variability. Isothermal calorimetry tests showed that high calcium fly ashes can lead to delays in hydration, these delays can be reduced by calcium hydroxide additions. Calcium sulphate additions can also improve hydration.
22

Potassium Acetate Deicer and Concrete Durability

Ghajar-Khosravi, Sonia 07 December 2011 (has links)
An investigation on the damaging effects of potassium acetate deicer (KAc) on concrete durability was conducted. Different SCM replacement levels were used. ASTM C 1293 and ASTM C 1260 test methods results indicated that KAc is capable of inducing alkali-silica reaction (ASR) expansion in specimens containing reactive aggregate. Class C fly ash was ineffective even at a replacement level of 45%. Class F fly ash and slag were effective in mitigating ASR expansion for specimens exposed to diluted (25% by weight) KAc. KAc showed an increase in pH value upon exposure to concrete specimens. Concrete specimen without SCM and exposed to deicers had higher [K]/[Na] molar ratio near the surface but ions penetrated less compared to specimens containing SCM. ASTM C 666 and MTO LS-412 test methods results showed that air-entrained concrete slabs and prisms without SCM and exposed to KAc are resistant to scaling and freezing and thawing damage.
23

Alternative Test Methods for Evaluating Fly Ash for use in Concrete

de Groot, Andre Pieter 23 August 2011 (has links)
Fly Ash was tested in relation to its ability to mitigate alkali-silica reaction, its contribution to strength, electrical resistance and heat release with the aim of recommending improvements to fly ash specifications. ASTM C 1567 accelerated mortar bar test results were in agreement with an expansion limit of 0.10 % at 14 days. A non-standard alkali leaching test showed that with high alkali fly ashes as replacement level increases the amount of alkalis leached increases while prism expansions decrease. Measures of pozzolanic activity can be improved by measuring against non-pozzolanic fillers, This requires high replacement levels to reduce statistical variability. Isothermal calorimetry tests showed that high calcium fly ashes can lead to delays in hydration, these delays can be reduced by calcium hydroxide additions. Calcium sulphate additions can also improve hydration.
24

Potassium Acetate Deicer and Concrete Durability

Ghajar-Khosravi, Sonia 07 December 2011 (has links)
An investigation on the damaging effects of potassium acetate deicer (KAc) on concrete durability was conducted. Different SCM replacement levels were used. ASTM C 1293 and ASTM C 1260 test methods results indicated that KAc is capable of inducing alkali-silica reaction (ASR) expansion in specimens containing reactive aggregate. Class C fly ash was ineffective even at a replacement level of 45%. Class F fly ash and slag were effective in mitigating ASR expansion for specimens exposed to diluted (25% by weight) KAc. KAc showed an increase in pH value upon exposure to concrete specimens. Concrete specimen without SCM and exposed to deicers had higher [K]/[Na] molar ratio near the surface but ions penetrated less compared to specimens containing SCM. ASTM C 666 and MTO LS-412 test methods results showed that air-entrained concrete slabs and prisms without SCM and exposed to KAc are resistant to scaling and freezing and thawing damage.
25

リチウムイオン内部圧入によるASR抑制効果に関する研究

江良, 和徳 23 March 2010 (has links)
Kyoto University (京都大学) / 0048 / 新制・課程博士 / 博士(工学) / 甲第15342号 / 工博第3221号 / 新制||工||1485(附属図書館) / 27820 / 京都大学大学院工学研究科社会基盤工学専攻 / (主査)教授 宮川 豊章, 教授 河野 広隆, 教授 西山 峰広 / 学位規則第4条第1項該当
26

Fast and Low-Latency End-to-End Speech Recognition and Translation / 高速・低遅延なEnd-to-End音声認識・翻訳

Inaguma, Hirofumi 24 September 2021 (has links)
京都大学 / 新制・課程博士 / 博士(情報学) / 甲第23541号 / 情博第771号 / 新制||情||132(附属図書館) / 京都大学大学院情報学研究科知能情報学専攻 / (主査)教授 河原 達也, 教授 黒橋 禎夫, 教授 森 信介 / 学位規則第4条第1項該当 / Doctor of Informatics / Kyoto University / DFAM
27

Évaluation adaptative des systèmes de transcription en contexte applicatif / Evaluation of automatic speech recognition systems according to the applicatives cases

Ben Jannet, Mohamed Amer 14 October 2015 (has links)
Il est important d'évaluer régulièrement les produits de l'innovation technologique afin d'estimer le niveau de maturité atteint par les technologies et d'étudier les cadres applicatifs dans lesquels elles pourront être exploitées. Le traitement automatique des langues (TAL) relève à la fois de la recherche et de l'innovation technologique et a pour but la modélisation et le développement d'outils permettant de traiter automatiquement le langage naturel. Pendant longtemps, les différentes briques technologiques issues du TAL étaient développées séparément. Par conséquent, les méthodes d'évaluation existantes sont dans la plupart modulaires et ne permettent d'évaluer qu'un seul module à la fois, alors qu'aujourd'hui nombreuses applications nécessitent de combiner plusieurs modules de TAL pour résoudre des tâches complexes. Le nouveau défi en terme d'évaluation est alors de pouvoir évaluer les différents modules (ou briques) tout en prenant en compte le contexte applicatif.Notre travail porte sur l'évaluation des systèmes de reconnaissance automatique de la parole (RAP) en contexte applicatif, en particulier, celui de la reconnaissance d'entités nommées (REN).En première partie, nous abordons la problématique de l'évaluation des systèmes de RAP en contexte applicatif à travers une étude de l'état de l'art. Nous y décrivons les tâche de RAP et de REN proposées dans les campagnes d'évaluation ainsi que les protocoles mis en place pour leurs évaluation. Nous y discutons également les limites des approches d'évaluations modulaires et nous y exposons les mesures alternatives proposées dans la littératures. En deuxième partie, nous décrivons la tâche de détection, classification et décomposition d'entités nommées étudiée et nous proposons une nouvelle métriques ETER (Entity Tree Error Rate) permettant de prendre en compte les spécificité de cette tâche et le contexte applicatif lors de l'évaluation. ETER permet également de supprimer les biais observés avec les métriques existantes. En troisième partie, nous définissons une nouvelle mesure ATENE (Automatic Transcriptions Evaluation for Named Entities) qui permet d'évaluer la qualité des systèmes de RAP et l'impact de leurs erreurs pour des systèmes de REN appliqués en aval. ATENE consiste à comparer les probabilités de présence d'entités sur les transcriptions de référence et d'hypothèse plutôt qu'une comparaison directe des graphèmes. Elle est composée de deux mesures élémentaires. Une première permettant l'évaluation de risque d'erreur d'omission et de substitution d'entités et une seconde permettant d'évaluer le risque d'erreur d'insertion d'entités causé par les erreurs de RAP.Nos expériences de validation montrent que les mesures données par ATENE corrèlent mieux que les autres mesures de l'état de l'art avec les performances des systèmes de REN. / It is important to regularly assess the technological innovation products in order to estimate the level of maturity reached by the technology and study the applications frameworks in which they can be used. Natural language processing (NLP) aims at developing modules and applications that automatically process the human language. That makes the field relevant to beth research and technological innovation. For years, the different technological modules from the NLP were developed separately. Therefore, the existing evaluation methods are in most modular. They allow to evaluate only one module at a time, while today, many applications need to combine several NLP modules to solve complex tasks. The new challenge in terms of evaluation is then to evaluate the different modules while taking into account the applicative context.Our work addresses the evaluation of Automatic Speech Recognition (ASR) systems according to the applicative context. We will focus on the case of Named Entities Recognition (NER) from spoken documents transcriped automatically. In the first part, we address the issue of evaluating ASR systems according to the application context through a study of the state of the art. We describes the tasks of ASR and NER proposed during several evalution campaigns and we discuss the protocols established for their evaluation. We also point the limitations of modular evaluation approaches and we expose the alternatives measures proposed in the literature. In the second part we describe the studied task of named entities detection, classification and decomposition and we propose a new metric ETER (Entity Tree Error Rate) which allows to take into account the specificity of the task and the applicative context during the evaluation. ETER also eliminates the biases observed with the existing metrics. In the third part, we define a new measure ATENE (Automatic Transcriptions Evaluation for Named Entities) that evaluates the quality of ASR systems and the impact of their errors for REN systems applied downstream. Rather than directly comparing reference and hypothesis transcriptions, ATENE measure how harder it becames to identify entities given the differences between hypothesis and reference by comparing an estimated likelihood of presence of entities. It is composed of two elementary measurements. The first aims to assess the risk of entities deletions and substitutions and the second aims to assess the risk of entities insertions caused by ASR errors.Our validation experiments show that the measurements given by ATENE correlate better than other measures from the state of the art with the performance of REN systems.
28

Formación de contaminantes y estudio cinético de la descomposición térmica de dos combustibles alternativos: CDR y ASR

Rey Martínez, Lorena 11 July 2016 (has links)
No description available.
29

Risikobetrachtung für den Asphaltaus- und -einbau im Grenzbereich zum fließenden Kraftfahrzeugverkehr unter Berücksichtigung der Standardarbeitsverfahren und Arbeitsmittel

Krell, Klaus-Michael 01 October 2020 (has links)
Jeden Tag sind auf Straßenbaustellen in Deutschland unzählige Versicherte der BG BAU durch den fließenden Straßenverkehr gefährdet. Zirka eineinhalb Jahren nach Inkraftsetzung der Regel für Arbeitsstätten ASR A 5.2 erfolgt eine Auswertung über die Umsetzung dieser Regel - hierbei soll speziell der Asphaltaus- und -einbau betrachtet werden. Ist der Mitgänger neben der Asphaltfräse bzw. neben dem Asphaltfertiger im Grenzbereich zum fließenden Verkehr tätig, so ist dieser beson-ders gefährdet. Das Ziel dieser Masterarbeit ist zum einen zu ermitteln, welche Standardarbeitsverfahren im As-phaltaus- und - einbau in der Regel für Arbeitsstätten nicht beschrieben sind. Für diese soll dann eine Tätigkeitsanalyse und Risikobetrachtung gemacht werden. Hierbei ist festzustellen, dass für den Einbau von bituminösen Asphalttragschichten im Handeinbau die größte, bisher nicht aufge-führte freie Bewegungsfläche benötigt wird. Zum anderen wird der Mitgängerbetrieb neben der Aspahltfräse bzw. dem Asphaltfertiger betrachtet. Dazu werden die folgenden Forschungsfragen gestellt. - Welche Aufgaben nimmt der Mitgänger bei seiner Tätigkeit wahr? - Wieviel Zeit verbringt der Mitgänger am Aussenbedienstand eines Straßenfertigers im Lauf einer Arbeitsschicht? - Welche technischen und organisatorischen Möglichkeiten gibt es die freie Bewegungsfläche und den seitlichen Sicherheitsabstand zu reduzieren? - Welche technischen und organisatorischen Möglichkeiten gibt es, den Mitgängerbetrieb überflüssig zu machen oder auf ein Minimum zu beschränken? Um die Forschungsfragen zu beantworten, ist neben Literaturrecherchen und Experteninterviews, eine deutschlandweite Befragung von Beschäftigten auf Straßenbaustellen durchgeführt worden. Die Befragten stellen im großen Umfang fest, dass es durch das in Kraft setzen der Regel für Arbeitsstätten Verbesserungen im Bereich des Arbeitsschutzes gegeben hat, diese aber eher im Bereich von Bundesfernstraßen zum Tragen kommen.
30

Evaluation and Preliminary Design of a Stormwater Aquifer Storage and Recovery (ASR) System at the Wadi Khulays Dunefield in Saudi Arabia

Lopez Valencia, Oliver M. 04 1900 (has links)
An important source of freshwater in arid lands is found in groundwater aquifers that are recharged after storm events. However, most of the precipitation is lost due to evaporation and only small fractions actually recharge the aquifers. The construction of dams along wadi channels enables the retention of stormwater, however the reservoirs are still subject to huge evaporative losses and contamination. In this study, the hydraulic properties of a dunefield in western Saudi Arabia are evaluated in order to determine the feasibility of designing a stormwater storage aquifer storage and recovery facility using the dune sands as a natural medium and design recommendations are addressed. The accurate estimation of hydraulic conductivity of unlithified sediments such as dune sands has become very important in the design of natural filtration projects, including aquifer recharge and recovery systems. Therefore, a comparison and selection of methods for the determination of the hydraulic conductivity from grain size distribution found in the literature was done. An improvement to these equations based on measurements on dune samples was obtained.

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