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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.
141

Studies on development of analytical methods to quantify protein aggregates and prediction of soluble/insoluble aggregate-formation / タンパク質の重合体に関する分析法開発及び可溶性/不溶性重合体形成予測に関する研究

Fukuda, Jun 23 March 2015 (has links)
京都大学 / 0048 / 新制・課程博士 / 博士(農学) / 甲第19025号 / 農博第2103号 / 新制||農||1030(附属図書館) / 学位論文||H27||N4907(農学部図書室) / 31976 / 京都大学大学院農学研究科応用生命科学専攻 / (主査)教授 加納 健司, 教授 植田 和光, 教授 植田 充美 / 学位規則第4条第1項該当 / Doctor of Agricultural Science / Kyoto University / DFAM
142

Εργαστηριακές δοκιμές καταλληλότητας γεωυλικών για την χρήση τους σαν αδρανή : Διερεύνηση μαγματικών πετρωμάτων Α / Laboratory tests for geomaterials for the use as aggragates : Investigation for magmatic rocks A

Λεπίδα, Παρασκευή 16 May 2014 (has links)
Η συγκεκριμένη διπλωματική εργασία, έγινε με σκοπό την λεπτομερή περιγραφή των τεχνικό-γεωλογικών χαρακτηριστικών που δύναται να ταξινομήσουν τα βραχώδη υλικά, ύστερα από εργαστηριακές δοκιμές και μετρήσεις, ως κατάλληλα ή μη κατάλληλα για την χρησιμοποίησή τους ως αδρανή υλικά. Στην εργασία, γίνεται εκτενής αναφορά στις φυσικές-μηχανικές–χημικές–γεωμετρικές και άλλες ιδιότητες που παρουσιάζουν τα υλικά που μπορούν να χρησιμοποιηθούν ως αδρανή, καθώς επίσης δίνεται και λεπτομερής περιγραφή των εργαστηριακών δοκιμών που διεξάχθηκαν, όπως προβλέπονται από τους Ευρωπαϊκούς Κανονισμούς (ΕΝ) περί καταλληλότητας των αδρανών υλικών που βρίσκονται σε συνάφεια με τις νομοθεσίες του Ελληνικού Κράτους. Η εν λόγω εργασία αναφέρεται στις χρήσεις αδρανών υλικών ως έρμα σιδηροδρομικών γραμμών και οδοποιίας. Εργαστηριακά, η παρακάτω διπλωματική εργασία βασίζεται στην λήψη δείγματος από βραχώδες διαβασικό και ηφαιστειακό υλικό το οποίο εξετάστηκε βάσει των πιο πάνω Ευρωπαϊκών Κανονισμών και στην συνέχεια συγκρίθηκε με τα προβλεπόμενα όρια της κάθε εργαστηριακής δοκιμής που αναφέρονται ως εργαστηριακά όρια χρήσης αδρανών υλικών σε έρμα σιδηροδρομικών γραμμών αλλά και οδοποιίας. Μια επιπλέον πτυχή του θέματος που εξετάζουμε είναι οι λατομικές ζώνες(λατομεία), οι οποίες ορίζονται ως ο χώρος που γίνεται μαζική λήψη υλικού, απευθείας από το υγιές τμήμα της βραχομάζας ,που προορίζεται για χρήση αδρανών υλικών και εξετάζονται οι περιορισμοί που προκύπτουν βάσει της Ελληνικής νομοθεσίας στο εν λόγω ζήτημα και αφορούν άμεσα αστικές και κατοικημένες περιοχές. Όλες οι εργαστηριακές δοκιμές που εκπονήθηκαν για το σκοπό αυτό, έλαβαν χώρα στο εργαστήριο Τεχνικής Γεωλογίας του τμήματος Γεωλογίας του Πανεπιστημίου Πατρών. Γίνεται επίσης σύγκριση των εργαστηριακών αποτελεσμάτων με τα αντίστοιχα κατάλληλα όρια. Τέλος, γίνεται γεωμορφολογική και γεωλογική αναφορά της περιοχής του Νομού Κιλκίς, Φλώρινας και Μεθάνων, από όπου πάρθηκαν τα δείγματα και δίνεται μια σύντομη αλλά κατατοπιστική αναφορά στην γεωτεκτονική ζώνη στην οποία ανήκει. / This thesis was aimed at a detailed description of the technical - geological characteristics may classify rocky materials, following laboratory tests and measurements, as suitable or unsuitable for use as aggregates. This paper is a detailed report on the physical - chemical - mechanical - geometric and other properties which are the materials that can be used as aggregates, as well as given and detailed description of the laboratory tests performed as specified by European regulations ( EN ) on suitability of aggregates that are consistent with the laws of the Greek state. This work relates to uses of aggregates as railway ballast and road construction. Laboratory, the following thesis is based on sampling from crossing rocky and volcanic material which was examined under the above European Regulations and then compared with existing limits of each laboratory test referred to as laboratory usage limits aggregates in railway ballast but and odopoiias.Mia additional aspect of the matter is the quarrying areas (quarries), defined as the space is massive samples taken directly from the healthy part of the rock mass, which is intended for use aggregates and examines the constraints arising under Greek law on this issue and directly related urban and residential areas. All laboratory tests carried out for this purpose took place in the laboratory of Engineering Geology, Geology Department, University of Patras. It will also compare the laboratory results with the corresponding appropriate limits. Finally Made geomorphological and geological report of the Prefecture of Kilkis, Florina and methane emissions, from which samples were taken and given a brief but informative reference to tectonic zone to which it belongs.
143

Contribution to the Understanding of the Rheological Behaviour of Recycled Concrete Aggregate Mixtures Made of Coarse and Fine Particles

Nagaraju, Yathiraj 29 June 2020 (has links)
The use of recycled concrete aggregates (RCA) has gained increased attention in the past few decades as an alternative to decrease the carbon footprint of concrete construction. Yet, most of the research performed so far demonstrates that RCA concrete displays inferior performance in the fresh and hardened states when compared to conventional concrete (CC). The latter is believed due to the fact that very often the different microstructure of RCA is not accounted for while the mix-proportioning of RCA concrete. Recently, a number of mix-design procedures accounting for RCA microstructure have been proposed. Amongst them, the Equivalent Volume (EV) method seems to be quite promising. The EV method may proportion RCA concrete made of coarse (CRCA) or fine (FRCA) RCA and is based on a companion CC. Previous research has demonstrated that the fresh and hardened properties of EV mix-designed CRCA are suitable for structural applications. Yet, very few research, analysis and quantification have been conducted on the fresh behaviour of EV mix- proportioned FRCA concrete. This work presents a comprehensive study on the rheological behaviour of EV mix-designed CRCA and FRCA concrete presenting distinct features (i.e. inner qualities, mineralogy, fabrication process, etc.) through the use of a planetary rheometer (IBB). Results show that the EV is capable of proportioning low embodied energy CRCA and FRCA concrete with shear thinning profiles. The latter suggests that these mixtures are suitable for applications under high torque regimes such as vibrated or pumped concrete.
144

Komparativna analiza osnovnih svojstava konstrukcijskih betona spravljenih sa različitim vrstama lakih agregata / A comparative analysis of the basic properties of structural concrete made with different types of lightweight aggregates

Lukić Ivan 09 April 2015 (has links)
<p>U disertaciji su prikazani rezultati sopstvenog eksperimentalnog istraživanja na osnovu kojih je izvršena komparativna analiza uticaja različitih vrsta lakih agregata i vrste i količine cementa na osnovna fizičko-mehanička svojstva lakoagregatnih betona. Takođe, analizirana je i mogućnost zamene dela cementa mineralnim dodacima u cilju smanjenja negativnih uticaja proizvodnje betona na životnu sredinu. Rezultati su pokazali da je primenom svih analiziranih vrsta agregata moguće dobiti konstrukcijski lakoagregatni beton, čak i sa manjim količinama cementa, odnosno sa zamenom dela cementa mineralnim dodacima, kao i da je moguće uspostaviti pouzdane korelacione veze između pojedinih svojstava betona i primenjenih komponentnih materijala.</p> / <p>In dissertation are presented results of own experimental research of a<br />comparative analysis of the impact of different types of lightweight<br />aggregates and the type and quantity of cement on basic physical and<br />mechanical properties of structural lightweight concrete. Also, the possibility<br />of replacing part of cement with mineral admixtures is analyzed in order to<br />reduce the negative impact of concrete production on the environment. The<br />results showed that it is possible to obtain structural lightweight aggregate<br />concrete with all types of lightweight aggregates and even with lower<br />quantities of cement or with a replacement of part of a cement with mineral<br />admixtures. Also, it is possible to establish a reliable correlation between<br />certain properties of concrete and used component materials.</p>
145

Estudo do uso de agregado reciclado de resíduos de construção e demolição em misturas solo-agregado / Study of the use of recycled aggregate of construction and demolition waste in soil-aggregate mixtures

Orioli, Monigleicia Alcalde 24 July 2018 (has links)
A construção civil gera impactos ambientais que merecem atenção especial, uma vez que é uma das áreas que mais produz resíduos dentre as atividades econômicas. Os agregados reciclados de resíduos de construção e demolição podem ser utilizados em diversas áreas, apresentando desempenhos mecânico e hidráulico adequados quando comparados aos agregados naturais. Esta pesquisa consiste em estudar a viabilidade o uso de agregado reciclado misto (ARM) e misturas solo-ARM como materiais geotécnicos em camadas de bases e sub-bases de pavimentos. Para isso, foram realizados ensaios de caracterização física e comportamento mecânico. Para comparação, foram estudados também um agregado natural (AN) e uma mistura de solo-AN. Os resultados mostraram que a energia de compactação teve efeito positivo sobre o comportamento do ARM e misturas de solo-ARM. Observou-se ainda que o ARM apresentou ganho de resistência e rigidez devido ao efeito de auto-cimentação. No que se refere à adição de solo, as misturas de solo-ARM apresentaram uma diminuição no valor de CBR em relação a misturas compostas exclusivamente por ARM, contudo houve um aumento nas demais propriedades mecânicas. Com base nos resultados obtidos, pode-se concluir que o ARM e as misturas solo-ARM apresentam características físicas e comportamento mecânico adequados para uso em camadas de base e sub-base de pavimentos urbanos. / Civil construction generates environmental impacts that deserve special attention, since it is one of the areas that produces the most waste among economic activities. The recycled aggregates of construction and demolition waste can be used in several areas, presenting adequate mechanical and hydraulic performances when compared to natural aggregates. This research consists of studying the feasibility of using recycled mixed aggregate (RMA) and soil-RMA mixtures as geotechnical materials in base and sub-base layers of pavements. For that, tests of physical characterization and mechanical behavior were carried out. For comparison, a natural aggregate (NA) and a soil-NA mixture were also studied. The results showed that the compaction energy had a positive effect on the behavior of RMA and soil-RMA mixtures. It was also observed that the RMA showed strength gain and stiffness due to the self-cementing properties. Concerning soil addition, the soil-RMA mixtures presented a decrease in the CBR value in relation to mixtures exclusively composed by RMA, but there was an increase in the other mechanical properties. Based on the results obtained, it can be concluded that the RMA and the soil-RMA mixtures present physical characteristics and mechanical behavior suitable for the use in base and sub-base layers of urban pavements.
146

Avaliação da influência do tipo de agregado, do tipo de ligante, do tipo de moldagem e do tipo de fíler na vida de fadiga de misturas asfálticas densas / An evaluation of aggregate type, asphalt type, molded type, and filler type on fatigue lifespan of asphalt mixtures

Iwanaga, Fabio Issao 20 August 2007 (has links)
Este trabalho tem como objetivo avaliar o comportamento à fadiga de algumas misturas asfálticas, à luz de resultados de ensaios de fadiga por compressão diametral à tensão controlada, considerando-se a variação de quatro fatores: tipo de agregado, tipo de ligante, tipo de moldagem e tipo de filler. Todos os corpos-de-prova foram moldados na mesma faixa granulométrica (centro da faixa C do DNER ), segundo os procedimentos dos métodos Marshall, ASTM D 4867 ou AASHTO T 283, variando o tipo de agregado (basalto, granito e gabro), tipo de ligante (CAP 20 e CAP 40) e o tipo de material de preenchimento (cal hidratada). São apresentados resultados dos ensaios de resistência à tração por compressão diametral, módulo de resiliência e de fadiga. Os modelos de fadiga são apresentados em função das diferenças de tensões e deformações. Para avaliar o desempenho relativo das misturas em serviço, foram simuladas três estruturas de pavimentos com a ajuda do programa ELSYM5, para as quais foram determinadas as tensões e deformações atuantes que foram utilizadas nos modelos de fadiga para que todas as misturas fossem avaliadas sob o mesmo referencial. Os resultados indicam que em relação ao tipo de moldagem, as misturas moldadas pelo método da AASHTO T 283 apresentaram melhor desempenho (maior vida de fadiga), sendo que a maioria das misturas moldadas com CAP 40 apresentou um desempenho melhor que as moldadas com CAP 20. Com relação ao tipo de agregado os materiais gábricos apresentaram o melhor desempenho, seguidos pelos basálticos e graníticos. As misturas moldadas com cal hidratada como filler também apresentaram melhor desempenho à fadiga. / The purpose of this research is to evaluate the fatigue behavior of some asphalt mixtures, by means of indirect tests with controlled stress, considering the variation of four factors: aggregate type, asphalt type, molded type and filler type. The specimens was molded in same gradation (center of DNER C gradation), according to Marshall, ASTM D 4867 or AASHTO T 283 design method, with the variation of three aggregates (basaltic, granite and gabbro), two asphalt (CAP 20 and CAP 40) and the presence of lime. Tests results of indirect tensile strength, resilient modulus and fatigue are presented. The fatigue models are constructed as a function of the differences of stress and strain. The fatigue behavior of asphalt mixtures was evaluated based on three structures which the stress and strains was estimated with aid of ELSYM5 program. The tests results indicated that all mixtures molded with AASHTO T 283 design method presented higher fatigue life than the other ones, and almost all asphalt mixtures molded with CAP 40 presented higher fatigue life than mixtures molded with CAP 20. Considering the type of aggregate, the specimens molded with gabbro presented higher fatigue life than basaltic and granite. The mixtures molded with presence of lime presented an increase in fatigue life.
147

Concretos leves com agregados inovadores de argila vermelha calcinada e subprodutos agroindustriais / Lightweight concrete with innovative calcined clay lightweight aggregates with agro-industrial by-products

Santis, Bruno Carlos de 18 November 2016 (has links)
Este trabalho tem por objetivo o estudo de concretos leves com agregados inovadores de argila vermelha calcinada e subprodutos agroindustriais. A argila utilizada na pesquisa foi caracterizada por meio das técnicas de limites de liquidez (LL) e plasticidade (LP), análise granulométrica, análise química e difração de raios X (DRX). Foram confeccionados corpos de prova de argila vermelha calcinada com incorporações de serragem de madeira, cinza do bagaço da cana-de-açúcar e silicato de sódio. Os corpos de prova de argila vermelha calcinada, queimados à temperatura de 900 °C, foram caracterizados por meio da avaliação da retração linear, absorção de água, porosidade aparente, massa específica aparente, expansão por umidade e resistência à compressão. Após a caracterização dos corpos de prova de argila vermelha calcinada, foram produzidos dois tipos de agregados, sendo o primeiro composto por 57% de argila e 43% de cinza do bagaço de cana-de-açúcar, conformados com água e silicato de sódio (proporção 1:1), e o segundo composto por 70% de argila e 30% de serragem de madeira. Os corpos de prova de concreto leve foram caracterizados pelos ensaios de slump, massa específica fresca, resistência à compressão, módulo de deformação, retração por secagem, absorção de água, índice de vazios e massa específica aparente e condutividade térmica. Os resultados desta pesquisa indicam a viabilidade da produção de agregados leves de argila vermelha calcinada com incorporações de subprodutos agroindustriais para utilização em concretos, uma vez que, mesmo com grande quantidade de utilização de subprodutos agroindustriais na produção dos agregados leves, os concretos produzidos com esses agregados apresentaram características similares aos concretos produzidos com agregados comerciais, apresentando um ganho econômico e energético significativo. / This paper aims to study lightweight concrete with innovative calcined clay lightweight aggregates made with agro-industrial by-products. The clay used in this research was characterized by techniques of liquid and plastic limits, particle size analysis, chemical analysis and X-ray diffraction (XRD). Calcined clay specimens were made with incorporations of wood sawdust, sugar cane ash and sodium silicate. These specimens, burned at a temperature of 900°C, were characterized by evaluating of linear shrinkage, water absorption, apparent porosity, specific mass, moisture expansion and compressive strength. After characterization of calcined clay specimens, two types of calcined clay lightweight aggregates with agro-industrial by-products were produced, wherein the first made with 57% of clay and 43% of sugar cane ash, mixed with water and sodium silicate (proportion 1:1) and the second made with 70% clay and 30% wood sawdust, mixed with water and burned at 900 °C. Specimens of lightweight concrete were characterized by slump test, fresh specific mass, compressive strength, modulus of elasticity, water absorption, voids and bulk density and thermal conductivity. Results of this research indicates the viability to produce calcined clay lightweight aggregates made with agro-industrial by-products to use in concrete, even using large amount of agro-industrial by-products, once concretes made with lightweight aggregates with agro-industrial by-products presented similar characteristics than those made with commercial aggregates, presenting significant energetic gain.
148

Fault Tolerance in Cryptographic Applications Using Cover-Free Families

Bardini Idalino, Thais 27 September 2019 (has links)
Cryptography is of fundamental importance to guarantee the security of communications, from the point-to-point transmission of messages and documents to the storage of big sets of data on cloud providers. As an example, we can use encryption, message authentication codes, and digital signatures to help us guarantee the privacy, integrity, and authenticity of data that is stored and/or transmitted. Many cryptographical solutions have a Boolean outcome, for example, the message is either authentic and accepted as it is, or it is not and so it needs to be rejected/re-transmitted. This outcome may be acceptable in scenarios where we can easily re-transmit the message, but it can pose a challenge when we deal with a large amount of data or a more sensitive content in which changes need to be further explored. In this context, this thesis proposes solutions to provide fault tolerance to certain cryptographic problems that traditionally have an all-or-nothing outcome. Fault tolerance is application dependent. In the case of a digital signature of a doc- ument that has been later modified, a fault-tolerant scheme can ensure authenticity and further identify which parts of the document were modified. This approach can be used in data forensics to investigate cybercrime, or to create redactable signatures for the purpose of privacy. In the case of aggregation of signatures, we consider an aggregation of a set of signatures containing a few invalid signatures (in the traditional sense). A fault-tolerant scheme is able to identify which signatures are valid and which ones are invalid, instead of rejecting the whole set. Digital signatures and aggregation of digital signatures require fault tolerance to be ensured at the origin (signer algorithm and aggregation algorithm, respectively), rather than just at the destination (verification algorithm). For this rea- son, we focus on techniques from combinatorial group testing that are nonadaptive rather than adaptive. This is in contrast with other applications of group testing, such as batch verification of signatures, employed at the verifier’s end which allow both adaptive and nonadaptive solutions. In this work, we explore solutions for fault tolerance using techniques of identification of defective elements used in nonadaptive combinatorial group testing. More specifically, we use the well studied cover-free families (CFFs). A d-cover-free family d-CFF(t, n) is a set system with n subsets of a t-set, where the union of any d subsets does not contain any other. A d-CFF(t, n) allows for the identification of up to d defective elements in a set of n elements by performing only t tests (typically t ≪ n). In the literature, CFFs are used to solve many problems in cryptography. In this work, we explore different aspects of cover-free families in order to better approach fault tolerance problems. The problems we investigate can be divided into two categories: static problems (fixed size) and dynamic problems (increasing size). In the context of static problems, we consider modification-tolerant digital signature schemes, which allow the identification of modifica- tions in signed data using a d-CFF, and in some cases the correction of such modifications in order to retrieve the originally signed data. We also propose a generalization of the classical definition of a d-CFF to support variable cover-free property, followed by some constructions and potential applications in cryptography. For dynamic problems, we con- sider the application of fault-tolerant aggregation of signatures. This problem requires an ii infinite sequence of CFFs with increasing n, consequently increasing t, and potentially in- creasing d. In this context, we investigate monotone, nested, and embedding sequences of CFFs, and propose constructions using techniques from combinatorial design theory and finite fields. In constructing these families, we are concerned with their compression ratio. The compression ratio of a sequence of CFFs measures how slowly the number of tests grow with respect to the number of elements to be tested, which affects the overall efficiency of the method. We provide constructions of CFF sequences with different compression ratios, which depend on relations among the CFF parameters in the sequence and the type of sequence. Some of these sequences achieve the best possible compression ratio, which meets the best known upper bound. Monotone, nested and embedding sequences of CFFs can be used in any group testing problem that is dynamic in nature. We discuss various cryptographical applications that can benefit from these infinite sequences of CFFs.
149

Verslo sistemų modelio analizė, panaudojant agregatinę schemą ir loginį programavimą / Analysis of business systems REA model using aggregate schema and logic programming

Janušauskaitė, Živilė 06 June 2006 (has links)
This work presents business process analysis methodology which consists of presentation of the business processes created on the ground of the Resource Event Agent model by means of Piece–Linear Aggregate approach. The aggregate specification is analyzing using first order predicate logic while checking correctness by resolution method using logic programming based language Prolog. The work is concluded with concrete example of analysis of Resource Event Agent model based business process using the aggregate approach. The novelty of this work PLA (Piece-Linear Aggregate) model and the software tools, created on the ground of PLA (Piece-Linear Aggregate), are used the first time for business processes analysis that is defined using REA formalism. The use of such integrated models allows performing the automated analysis of general and individual properties (completeness, deadlock freeness, termination or cyclic behavior, boundedness) of defined business processes. The main results are achieved: • The methodology, that consists of presentation of the business processes created on the ground of the Resource Event Agent model by means of Piece–Linear Aggregate approach. • Verification and validation of general and individual properties by using PLA and PROLOG language approach designed system that executes the analysis of aggregate specification. • Implementing internal accounting controls as constraints in relational algebra, SQL and PROLOG language. • Concrete... [to full text]
150

Geophysical Imaging and Numerical Modelling of Fractures in Concrete

Katsaga, Tatyana 13 August 2010 (has links)
The goal of this research is to investigate the fundamentals of fracturing processes in heterogeneous materials such as concrete using geophysical methods and dynamic micromechanical models. This work describes how different aspects of fracture formation in concrete can be investigated using a combination of Acoustic Emission (AE) techniques, ultrasonic wave velocity imaging, and high resolution Computed Tomography (CT). Fracture formation and evolution were studied during shear failure of large reinforced concrete beams and compressive failure of concrete samples. AE analysis includes studying complex spatial and temporal fracture development that precedes shear failure. Predominant microcrack mechanisms were analyzed at different stages of fracture formation. CT images were used to investigate the influence of concrete microstructure on fracture topography. Combined AE and CT damage evaluation techniques revealed different aspects of fracture development, thus expanding our understanding of AE events and their mechanisms. These images show how aggregate particles influence fracture nucleation and development. An emphasis has been placed on the role of coarse aggregates during the interlocking of fracture surfaces at transferring shear stresses. Ultrasonic wave velocity and AE techniques have been applied to uniaxial compression tests of concrete with various aggregate sizes and strengths similar to that of the concrete beams. AE parameters, p-wave velocities, and stress-strain data have been analyzed concurrently to image damage evolution under compression. Influence of material composition on microcracking and material state changes during loading has been investigated in detail. The results of compressive tests were used as building blocks for developing realistic micromechanical numerical models of concrete. The models were designed using a distinct element code, where material is modelled through the combination of bonded particles. A number of procedures were developed to transfer the exact microstructure of material incorporating its visual representation into the model. The models’ behaviour has been verified against experimental data. It was shown that these models exhibit realistic micromechanical behaviour. The results of the experimental investigation of concrete fracturing were expanded by modelling more cases with aggregate size and strength variations. It was shown that geophysical imaging techniques, along with advanced micromechanical numerical modelling, can help us understand damage formation and evolution.

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