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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.
1

Etude des transferts de petites molécules au travers des films comestibles encapsulant des substances actives (arômes)

Mercado, Alicia 16 September 2010 (has links) (PDF)
Ce travail de thèse avait pour objectif de mieux comprendre l'influence de l'incorporation d'une molécule active (arôme) et/ou de particules lipides sur la structure et les propriétés physico-chimiques de matrices filmogènes à base d'iota-carraghènane ou d'alginate de sodium. La microstructure, la granulométrie de l'émulsion filmogène, les caractéristiques thermiques et mécaniques des films ont été étudiées en présence ou non de n-hexanal. Les propriétés de transfert de ces films ont été appréhendées grâce aux mesures de perméabilité à l'oxygène, à la vapeur d'eau et à l'eau liquide, au n-hexanal et au D limonène à l'état vapeur et liquide et à 6 autres composés d'aromes (esters d'éthyle, cétone et alcools). L'ajout de n-hexanal dans la matrice d'iota-carraghènane modifie le processus de gélification ce qui induit la formation d'une microstructure plus homogène mais ayant une résistance mécanique moindre, augmente la perméabilité à la vapeur d'eau mais diminue légèrement celle de l'hexanal. Quant aux films d'alginate, ils sont peu sensibles à la présence de n-hexanal. Cette différence de comportement est attribuée aux interactions entre la fonction aldéhyde de l'arôme et les groupes OH et sulfate du carraghènane qui perturbent la formation des hélices lors de la gélification. L'organisation du gel d'alginate en boite à œuf lui confère une plus grande stabilité. L'ajout de lipide permet de diminuer la sorption et la perméabilité à la vapeur d'eau des matrices filmogène. En présence de la matière grasse, l'hexanal se comporte comme un émulsifiant et semble être localisé en surface des globules en augmentant la finesse et la stabilité des émulsions filmogènes. Les paramètres cinétique (diffusivité) et thermodynamique (sorption) ont été mesurés pour mieux caractériser les mécanismes impliqués dans le transfert Enfin, le paradoxe de Schroeder, correspondant à la différence de flux selon l'état physique de la molécule diffusante, a été observé et expliqué pour l'eau dans les films d'alginate et pour l'hexanal dans les films de carraghènanes.
2

Adhezivní vlastnosti matricových tablet / Adhesive properties of matrix tablets

Kišková, Martina January 2021 (has links)
Charles University, Faculty of Pharmacy in Hradci Králové Department of Pharmaceutical Technology Name: Martina Kišková Title of diploma thesis: Adhesive properties of matrix tablets Supervisor: PharmDr. Eva Šnejdrová, Ph.D. The diploma thesis deals with the evaluation of rheological and adhesive properties of the mucin, aqueous dispersions of polymeric carriers and matrix tablets based on chitosan and sodium alginate or iota-carrageenan loaded with the salicylic acid using absolute rotational rheometer. The theoretical part deals with the characterization and classification of matrix tablets, polymeric carriers (sodium alginate, chitosan and carrageenan) and with the principles of evaluation of rotational, adhesive and oscillational tests performed in the experimental part. The mucin from porcine gastric used as a model substrate for adhesion tests behaves as a viscoelastic solid and its adhesive strength decreases with increasing hydration. Significantly higher adhesive strength was found for chitosan at pH 1.2 and sodium alginate at pH 6.8 compared to the adhesive strength of iota-carrageenan. In terms of viscoelastic properties, chitosan and sodium alginate are viscoelastic fluids, but iota-carrageenan is a viscoelastic solid. Iota-carrageenan forms the stiffest gel after hydration at pH 6.8...
3

A performance da MHTΣ e de Odisseu nos livros V e XII das Pós-Homéricas de Quinto de Esmirna / The performance of MHTΣ and Odysseus in the Books V and XII of the Quintus of Smyrna Posthomerica

Pasqual, Erika Mayara 15 August 2018 (has links)
Entre os séculos III e IV d.C., no Período Imperial, Quinto de Esmirna compôs uma epopeia posteriormente intitulada Pós-Homéricas. Dentre as quatorzes partes que compõem o poema, os Livros V (O julgamento das armas) e XII (O cavalo de madeira) enaltecem a atuação da μῆτις em relação ao ambiente bélico, bem como exibem a depreciação acerca de seu modo de operação. Entretanto, ela se revela como uma habilidade vantajosa aos guerreiros por seu caráter múltiplo, capaz de mudar situações, sair de impasses e assegurar o sucesso àquele que for mais πολύμητις nas interações sociais e estratégicas. Desse modo, Odisseu torna-se um líder vital para que a guerra troiana chegue ao fim e, essencialmente, garante a vitória ao exército aqueu. Nesse sentindo, o trabalho pretende examinar o quanto a μῆτις e o herói astucioso são componentes imprescindíveis para o curso das ações. Ademais, a tradução dos Livros V e XII complementam o estudo e promovem o conhecimento sobre parte da obra. / Between the 3rd and 4th centuries A.D., during the Empire Period, Quintus of Smyrna composed an epic poem later called Posthomerica. Among the fourteen parts that compose the poem, Books V (The judgement of the arms) and XII (The wooden horse) praise the action of μῆτις in the war environment, while also depreciating its modus operandi. However, μῆτις reveals itself as an advantageous skill for warriors due to its varied character, capable of changing situations, escape impasses, and assure the success of the one who is better πολύμητις in the social and strategic interactions. Thus, Odysseus becomes an essential leader for the Trojan War to meet its end and is the primary responsible for the Achaean armys victory. In this sense, this study aims to examine how μῆτις and the astute hero are indispensable for the course of actions throughout the poem. Furthermore, the translations of Books V and XII complement the study and foster knowledge on part of the poem.
4

[pt] LEDGERS SEGUROS E DISTRIBUÍDOS PARA SUPORTAR DADOS DE TECNOLOGIA IOT / [en] SECURE DISTRIBUTED LEDGERS TO SUPPORT IOT TECHNOLOGIES DATA

ADRIAN CONCEPCION LEON 18 January 2022 (has links)
[pt] Blockchain e Tangle são estruturas de dados usadas para criar um registro público imutável de dados segurados por uma rede de participantes peer-to-peer que mantém um conjunto de registros de dados em constante crescimento conhecidos como ledgers. As tecnologias Blockchain e Tangle são uma solução descentralizada que garante a troca de grandes quantidades de mensagens confiáveis, entre bilhões de dispositivos de IoT conectados, os quais são muito valiosos, desde que sejam válidos e completos. Esse mecanismo de mensagens peer-to-peer altamente criptografado e seguro é adotado neste projeto para gerenciar o processamento de transações de IoT e a coordenação entre os dispositivos que interagem com o processo. Para manter as transações privadas e seguras, os algoritmos de consenso distribuídos são responsáveis por validar e escolher as transações e registrá-las no ledger global. Os resultados mostraram que a velocidade dos algoritmos de consenso pode afetar a criação em tempo real de histórias confiáveis que rastreiam os eventos das redes IoT. Após incorporar o Processamento de Eventos Complexos, que permite selecionar apenas os eventos de alto nível, é possível obter uma melhoria em muitas situações. O resultado é um sistema Middleware que fornece framework para a construção de aplicativos de larga escala onde podem usar Processamento de Eventos Complexos e diferentes ledgers descentralizados, como o blockchain da Ethereum ou IOTA Tangle, para armazenamento seguro de dados. / [en] Blockchain and Tangle are data structures and protocols used to create an immutable public record of data ensured by a network of peer-to-peer participants that maintain a monotonic constantly growing set of data records known as ledgers. Both technologies provide a decentralized solution that guarantees the exchange, among billions of IoT devices, of large amounts of trusted messages, which are very valuable as long as they are valid and complete. This highly encrypted and secure peer-to-peer messaging mechanism is adopted in this project to manage the processing of IoT transactions. To maintain transactions private, and secured consensus algorithms are responsible for validating and choosing transactions and recording them in the global ledger. The results showed that the speed of the consensus algorithms can affect the creation in real-time of reliable stories that track the events of the IoT networks. After incorporating Complex Event Processing that allows selecting only those high-level events, it is possible to obtain an improvement in many situations. The result is a Middleware system that provides a framework for the construction of large-scale computer applications that use Complex Events Processing and different decentralized ledgers such as the blockchain of Ethereum or IOTA Tangle, for secure data storage.
5

Impact of the Distributed Ledger Technology (DLT) IOTA on Smart Cities / Effekten av den distributed ledger technology (DLT) IOTA på smarta städer

STEINER, BENEDIKT, NEIDLINGER, VINCENT January 2021 (has links)
This article analyses the impact of the IOTA distributed ledger technology (DLT) on smart cities. The world population is rapidly increasing while at the same time trends such as urbanization shape future demographics. Thus, fast-growing cities face the challenge of increasing demands in resources such as energy, water, transportation, while at the same time aiming to increase life quality by reducing burdens such as pollution and waste. The concept of a “Smart City” emerged with the ambition to solve a city’s issues by creating social and economic advantages while providing efficient resource allocation processes. Nevertheless, current information communication technologies tend to underperform a smartcities systems requirement since the quantity of connected devices increases which slows down the transition of a city becoming smart. The distributed ledger technology IOTA promises to enable automated, feeless transactions and processes with a high level of integrity, which may impact the development of smart cities. In this research the IOTA technology is introduced and investigated. The advantages of IOTA compared to conventional information communication technologies and the blockchain technology are highlighted. Thereafter, the current state of IOTA in smart cities is reviewed by analysing current research and use cases. To investigate the concept of a smart city the smart city initiative framework, including its subcategories is introduced. Additionally, different experts working on IOTA integrations related to smart city initiatives were interviewed giving insights into their field ofexpertise. Finally, an analysis and discussion of the IOTA technology use cases are put into relation with the multi-level perspective framework (Geels, 2006) highlighting the positive impact of IOTA on the development of smart cities. / I den här artikeln analyseras effekterna av IOTA:s teknik för distribuerade huvudböcker (DLT) på smarta städer. Världens befolkning ökar snabbt samtidigt som trender som urbanisering formar framtidens demografi. Snabbt växande städer står därför inför utmaningen att öka kraven på resurser som energi, vatten och transporter, samtidigt som de strävar efter att öka livskvaliteten genom att minska belastningar som föroreningar och avfall. Begreppet smart stad uppstod med ambitionen att lösa stadensproblem genom att skapa sociala och ekonomiska fördelar och samtidigt tillhandahålla effektiva processer för resursfördelning. Den nuvarande informations- och kommunikationstekniken tenderar dock att inte uppfylla kraven på system för smarta städer, eftersom mängden anslutna enheter ökar, vilket gör att övergången till en smart stad blir långsammare. Den distribuerade huvudbokstekniken IOTA lovar att möjliggöra automatiserade, felfria transaktioner och processer med en hög grad av integritet, vilket kan påverka utvecklingen av smarta städer. I den här forskningen introduceras och undersöks IOTA-tekniken. Fördelarna med IOTA jämfört med konventionell informationskommunikationsteknik och blockkedjetekniken lyfts fram. Därefter granskas det nuvarande läget för IOTA i smarta städer genom att analysera aktuell forskning och användningsfall. För att undersöka begreppet smart stad introduceras ramverket för initiativet för smarta städer, inklusive dess underkategorier. Dessutom intervjuades olika experter som arbetar med IOTA-integrationer isamband med initiativ för smarta städer för att ge en inblick i deras expertisområde. Slutligen analyseras och diskuteras IOTA-teknikens användningsområden i förhållande till ramverket för flernivåperspektivet (Geels, 2006), där IOTA:s positiva inverkan på utvecklingen av smarta städer lyfts fram.
6

Etude des transferts de petites molécules au travers des films comestibles encapsulant des substances actives (arômes) / Study of small molecules transfers through edible films encapsulating active substances (aroma compounds)

Hambleton Mercado, Alicia 16 September 2010 (has links)
Ce travail de thèse avait pour objectif de mieux comprendre l’influence de l’incorporation d’une molécule active (arôme) et/ou de particules lipides sur la structure et les propriétés physico-chimiques de matrices filmogènes à base d'iota-carraghènane ou d'alginate de sodium. La microstructure, la granulométrie de l'émulsion filmogène, les caractéristiques thermiques et mécaniques des films ont été étudiées en présence ou non de n-hexanal. Les propriétés de transfert de ces films ont été appréhendées grâce aux mesures de perméabilité à l'oxygène, à la vapeur d'eau et à l'eau liquide, au n-hexanal et au D limonène à l'état vapeur et liquide et à 6 autres composés d'aromes (esters d'éthyle, cétone et alcools). L'ajout de n-hexanal dans la matrice d'iota-carraghènane modifie le processus de gélification ce qui induit la formation d'une microstructure plus homogène mais ayant une résistance mécanique moindre, augmente la perméabilité à la vapeur d'eau mais diminue légèrement celle de l'hexanal. Quant aux films d'alginate, ils sont peu sensibles à la présence de n-hexanal. Cette différence de comportement est attribuée aux interactions entre la fonction aldéhyde de l'arôme et les groupes OH et sulfate du carraghènane qui perturbent la formation des hélices lors de la gélification. L'organisation du gel d'alginate en boite à œuf lui confère une plus grande stabilité. L'ajout de lipide permet de diminuer la sorption et la perméabilité à la vapeur d'eau des matrices filmogène. En présence de la matière grasse, l'hexanal se comporte comme un émulsifiant et semble être localisé en surface des globules en augmentant la finesse et la stabilité des émulsions filmogènes. Les paramètres cinétique (diffusivité) et thermodynamique (sorption) ont été mesurés pour mieux caractériser les mécanismes impliqués dans le transfert Enfin, le paradoxe de Schroeder, correspondant à la différence de flux selon l'état physique de la molécule diffusante, a été observé et expliqué pour l'eau dans les films d'alginate et pour l'hexanal dans les films de carraghènanes. / The aim of this work was a better understanding of the effect of the aroma and/or lipid particles incorporation on the structure and physico-chemical properties of film-forming matrices based on iota-carrageenan or sodium alginate. Microstructure, emulsion granulometry, thermal and mechanical properties were assessed as a function of n-hexanal and/or lipid presence. Barrier efficiencies to water, n-hexanal and D-limonene at liquid and vapour states, and to 6 other aroma vapours (ethyl esters, alcohols, keton) have been measured. When n-hexanal is added in the carrageenan matrix, it modifies the gelation process which induces a more homogeneous structure but a lower mechanical resistance, a higher permeability to water and n-hexanal but slightly decreases that to oxygen. On the contrary, the aroma compound introduction does not affect so much the alginate film characteristics. This behaviour difference is due to the interaction between aldehyde group of the aroma compound and OH and sulphate groups of the carrageenans which disturbs the helix formation during gelation. The organisation of the alginate network as an "egg box" makes it more stable which explain it lower sensitivity to the aroma addition. When lipids are added, both sorption and water vapour permeability and the mechanical properties are reduced. The n-hexanal acts as an emulsifier by improving the emulsion droplet size and preventing the aggregation. Indeed, the aroma compound seems to be localised at the lipid particle surface. Kinetic (diffusivity) and thermodynamic (sorption coefficient) were measured or estimated to better characterise the aroma and moisture transfers through the hydrocolloid based films. Finally, discrepancy between liquid and vapour transfer rate measured for the same activity gradient (= Schroeder paradox), was observed for water through alginate films and for n-hexanal through carrageenan films. This was attributed to swelling and partial solubilisation of film components in the diffusing substance.
7

TUF on the Tangle : Securing software updates using a distributed ledger / Verifiering av mjukvaruuppdateringar på en distribuerad ledger

Johns, Oliver, Andell, Anton January 2021 (has links)
This study investigates the viability of revising The Update Framework (TUF) to be implemented on a distributed ledger called IOTA. TUF is a framework that is becoming the de facto standard for securing update systems. The design for the revised Update Framework, called TUFT, is thoroughly explained and examined. A security analysis  as well as a performance analysis are made for the proposed design and prototype respectivly. Security-wise, TUFT is determined to be more secure than the original framework. On the other hand, TUFT is shown to be slower than the original TUF, with some scalability issues due to the requirement to fetch the whole update history for a repository. To accompany a wider range of software we also introduce new features in TUFT that provide versioning and mapping. The work done shows that a distributed ledger can improve a system like TUF in regards to security, auditability, and immutability. In summary, the proposed TUFT design is promising with its new features although it is limited performance-wise in some regards. With the updates being done to the IOTA ledger, a system like TUFT could be further improved upon to reduce the performance impact.
8

Distributed Data Management in Internet of Things Networking Environments : IOTA Tangle and Bitcoin Blockchain Distributed Ledger Technologies

Ruiz, Gerard January 2018 (has links)
Distributed ledger technology (DLT) is one of the latest in a long list of digital technologies, which appear to be heading towards a new industrial revolution. DLT has become very popular with the publication of the Bitcoin Blockchain in 2008. However, when we consider its suitability for dynamic networking environments, such as the Internet of Things, issues like transaction fees, scalability, and offline accessibility have not been resolved. The IOTA Foundation has designed the IOTA protocol, which is the data and value transfer layer for the Machine Economy. IOTA protocol uses an alternative blockless Blockchain which claims to solve the previous problems: the Tangle. This thesis first inquires into the theoretical concepts of both technologies Tangleand Blockchain, to understand them and identify the reasons to be compatible or not with the Internet of Things networking environments. After the analysis, the thesis focuses on the proposed implementation as a solution to address the connectivity issue suffered by the IOTA network. The answer to the problem is the development of a Neighbor Discovery algorithm, which has been designed to fulfill the requirements demanded by the IOTA application. Dealing with IOTA network setup can be very interesting for the community that is looking for new improvements at each release. Testing the solution in a peer-to-peer specific protocol (PeerSim), with different networking scenarios, allowed us to get valuable and more realistic information. Thus, after analyzing the results, we were able to determine the appropriate IOTA network configuration to build a more reliable and long-lasting network.
9

Utveckling av en adapter till en öppen energiplattform

Lithell, Joakim, Johansson, Per January 2014 (has links)
Målet med denna studie är att utveckla en adapterprototyp mot en öppen energiplattformoch dokumentera utvecklingsprocessen. Fokus ligger på att integreraPhilips Hue, ett system för styra trådlösa lampor mot plattformen Elis (Mobile servicesfor energy e ciency in existing buildings). Inom en begränsad tidsram så skavi sätta oss in i två främmande system till en sådan grad att vi kan skapa kommunikationenmellan dem. Inledningsvis krävs det att vi läser dokumentation och att vijobbar fram en arbetsplan. Vidare kommer vi lösa den adaption som krävs för attvärden mellan det två systemen överensstämmer och fungerar. Vi kommer användaoss av intervjuer för att få klarhet i hur plattformen är uppbyggd och grunden tillderas designval. Metoden design research används för att på ett iterativt sätt skapadelmål och successivt utveckla och utvärdera arbete. Målet med design research äratt skapa en artefakt, en adapterprototyp i vårt fall. Vi gjorde totalt fyra iterationerdär vi delade upp arbetet. Steg ett var att lära oss om plattformen, steg två lära ossPhilips Hue. Först i steg tre började vi utveckla vår adapterprototyp med kunskapenfrån det första iterationerna Slutligen intervjuade vi utvecklare i Elis och prata meddom om vad vi har kommit fram till och diskuterade fördelarna och nackdelarna vistött på vid utveckling mot deras plattform. Vi kommer med synpunkter och sakervi anser kan förbättras och hur adaptern bidrar till ett Elis ur ett software ecosystemperspektiv.. . . / The purpose of this essay is to develop an adapter prototype for an open energyplatform and document the development process. We focus on integrating PhilipsHue personal wireless lighting unto the platform Elis (Mobile services for energye ciency in existing buildings). Within the short timeframe of this study we intendto reach a level of understanding enough to make the systems communicate usingour adapter prototype. Initially we study documentation and prepares a work plan.Further more we try to solve the adaptation needed for the two system to communicate,this involves converting and matching up values. We will do some interviewswith the developers of Elis to get the big picture of how and why they designed theplatform they way it is. The research paradigm design research is a iterative methodologythat creates milestones, develop prototypes and evaluate the work. Thegoal of design research is to create an artifact, in our case an adapterprototype. Wemade a total of four iterations where the work was divided. Step one was to learnhow the platform works and step two was to study Philips Hue. At step three theimplementation of our prototype with the preparatory work from the rst iterationscould begin. The nal step was to interview members of Elis development team to nd out the impact of our work and to discuss the pros and cons of working withtheir platform. We present opinions and ndings of things we have found that canbe improved. We also de ne how our adapter bene ts Elis in a software ecosystemperspective.. . .
10

Understanding Cryptocurrencies from a Sustainable Perspective : Investigating cryptocurrencies by developing and applying an integrated sustainability framework

Arps, Jan-Philipp January 2018 (has links)
With the invention of the cryptocurrency Bitcoin in 2009, the world's first blockchain application was developed. While academic research gradually begins to investigate cryptocurrencies more closely and attempt to understand their functioning, technology is rapidly evolving and ecosystems grow exponentially. The research is still scattered and chaotic and has not produced common guidelines. Therefore, the question remains: how sustainable cryptocurrencies and their digital ecosystems are.Only a few models and frameworks take a holistic view on digital sustainability. Only two frameworks were identified that take distributed ledger technologies (blockchain) or cryptocurrencies into consideration: the three governance strategies for digital sustainability of Linkov et al. (2018) and 10 basic conditions of sustainable digital artifacts according to Stuermer, Abu-Tayeh and Myrach (2016). These two frameworks were combined into a new integrated sustainability framework for cryptocurrencies. The developed integrated sustainability framework consists of four dimensions and 12 categories.Existing secondary data, self-conducted social media interviews and practical insights gained through an ASIC mining experiment were used to fill the framework with sufficient data. It confirms Bitcoin's sustainability problems in energy consumption and scalability, highlights Ethereum's great potential as a blockchain platform and explains the higher scalability and faster payment of Ripple and IOTA.While 2017 marked the temporary peak of the cryptocurrency hype, 2018 was a transformative year in which the leading cryptocurrencies were increasingly occupying more specialised niches.

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