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

Studium vlivu složení na sypné a konsolidační vlastnosti tabletoviny / Study of the influence of tablet mixture composition on the flow and consolidation properties

Ferechová, Daniela January 2021 (has links)
Charles University, Faculty of Pharmacy in Hradci Králové Department of: Supervisor: Pharmaceutical Technology doc. PharmDr. Zdeňka Šklubalová, Ph.D. Consultant: Mgr. Jana Brokešová Student: Daniela Ferechová Title of Thesis: Study of the influence of tablet mixture composition on the flow and consolidation properties Good flow properties of a tabletting mixture play an important role in the manufacturing of tablets. Flow behaviour of the commercial (original) tabletting mixture with poor flowability was evaluated in this thesis. The main aim was to find alternative fillers that may improve its flow. The granulometric characteristics and flowability of eight types of lactose and microcrystalline cellulose and their binary mixtures were studied. In comparison to the original tabletting mixture, the proposed modified one with both original fillers were replaced with new ones showed significantly better flow properties with steady state flow through the hopper orifice having a diameter of 10 mm. The results were confirmed using powder rheometer. The lower shear stress necessary to achieve flow under different normal loads as well as approximately 72 times lower cohesion value were detected for the modified tabletting mixture.
42

Formulace lyofilizovaných tablet pro bukální aplikaci vakcín. / Formulation of freeze dried tablets for buccal application of vaccines

Vuová, Ngoc Lien January 2021 (has links)
Charles University, Faculty of Pharmacy in Hradec Králové Department of: Pharmaceutical Technology Mentor: Doc. PharmDr. Zdeňka Šklubalová, Ph.D. Student: Ngoc Lien Vuová Title of Thesis: Formulation of freeze dried tablets for buccal application of vaccines Mucosal vaccines represent an attractive way of vaccination with an advantage of inducing both systemic and local immunity. The aim of this diploma thesis was designing a composition of freeze-dried tablets for buccal administration of a model Bordetella pertusis vaccine. The easy removal from blister, firmness and aesthetic appearance as well as the appropriate taste and mucoadhesivity were the required product quality parameters. The excipients were characterised by differential scanning calorimetry, osmolality and pH measurement; the mechanical properties and disintegration time of freeze-dried tablets were evaluated. Among the variety of studied excipients and their combinations, dextran 40 as the main component of the preparation provided the best results. For the further modification of properties, the addition of fish gelatin, iota carrageenan and macrogol 300 is suitable. Freeze-dried tablets containing trehalose, mannitol and povidon 25 did not achieve the desirable quality parameters. Freeze- dried tablets containing iota carrageenan...
43

Development of sensing concrete: principles, properties and its applications

Ding, S., Dong, S., Ashour, Ashraf, Han, B. 14 November 2019 (has links)
Yes / Sensing concrete has the capability to sense its condition and environmental changes, including stress (or force), strain (or deformation), crack, damage, temperature and humidity through incorporating functional fillers. Sensing concrete has recently attracted major research interests, aiming to produce smart infrastructures with elegantly integrated health monitoring abilities. In addition to having highly improved mechanical properties, sensing concrete has multifunctional properties, such as improved ductility, durability, resistance to impact, and most importantly self-health monitoring due to its electrical conductivity capability, allowing damage detection without the need of an external grid of sensors. This tutorial will provide an overview of sensing concrete, with attentions to its principles, properties, and applications. It concludes with an outline of some future opportunities and challenges in the application of sensing concrete in construction industry. / National Science Foundation of China (51978127 and 51908103), the China Postdoctoral Science Fundation (2019M651116) and the Fundamental Research Funds for the Central Universities in China (DUT18GJ203). / National Science Foundation of China (NSFC) (Nos. 51978127 and 51908103), the China Postdoctoral Science Foundation (No. 2019M651116), and the Fundamental Research Funds for the Central Universities in China (No. DUT18GJ203).
44

Influence des sables fillérisés calcaires sur les propriétés des bétons courants et superplastifiés. Un exemple tunisien / Influence of limestones sands rich of fillers on the properties of the concretes with and without superplasticizer. A Tunisian example

Joudi-Bahri, Imène 10 November 2012 (has links)
L'objectif de la thèse est d'étudier l'effet de la quantité de fillers vis-à-vis des propriétés rhéologiques, mécaniques et dimensionnelles de bétons tout calcaire. Ces bétons ont été confectionnés avec les mêmes gravillons et le même sable provenant de la même production, afin d'éviter tout artéfact. Le sable a servi à fabriquer cinq sables représentatifs des catégories définies dans la norme EN 12260 des granulats à bétons, par mélange avec sa fraction fine ou sa fraction grenue extraites préalablement par lavage. Les sables fabriqués contiennent environ 0, 6, 12, 18 et 24% de fillers. Les bétons ont été formulés avec le logiciel BetonlabPro2, dont les algorithmes prennent en compte la présence des fillers calcaires. Les bétons ont été réalisés tout d'abord sans superplastifiant, puis en présence d'un superplastifiant dosé à 2/3 de la saturation. Les résultats obtenus ont montré qu'une quantité de fillers de 100 à 130 kg/m3 pour les bétons courants et de 60 à 80 kg/m3 pour les bétons superplastifiés, permet d'obtenir des propriétés optimales, à consistance égale. Mais des quantités supérieures de fillers n'altèrent pas significativement les propriétés des bétons, même si leur compacité diminue. On explique ce comportement non seulement par l'effet liant attribué aux fillers calcaires, mais aussi par une amélioration de la liaison pâte granulats. Les mélanges contenant les plus forts taux de fillers ont encore été étudiés pour formuler des bétons autoplaçants BAP, qui nécessitent une grande quantité de fillers. Les sables de concassage apportent alors la majeure partie de ce constituant, ce qui leur ouvre une voie nouvelle d'utilisation / The objective of this work is to study the effect of the quantity of fillers on the rheological, mechanical and dimensional properties of calcareous concretes. These concretes were made with the same coarse aggregates and same sand coming from the same production, in order to avoid any artifact. Sand was used to manufacture five sands representative of the categories defined in the EN 12260 norm for aggregates for concretes, by mixture with its fine fraction or its grained fraction extracted beforehand by washing. The employed sands contain approximately 0, 6, 12, 18 and 24 % of fillers. The concretes were formulated with the BetonlabPro2 software, whose algorithms take into account the presence of the fillers limestones. Concretes were realized at first without superplastifiant, then in the presence of a superplastifiant measured in 2/3 of saturation. The obtained results showed that a quantity of fillers limestones from 100 to 130 kg/m3 for the concretes and from 60 to 80 kg / m3 for superplasticizred concretes allows obtaining optimal properties, in equal consistency. But, higher quantities of fillers do not deteriorate significantly the properties of the concretes, even if their packing density decreases. One explains this behavior not only by the binding effect allotted to the fillers limestones, but also by an improvement of the paste-aggregates bond. Mixtures containing the strongest rates of fillers were again studied to formulate self compacting concretes SCC, which require a big quantity of fillers. Crushed sands bring then the major part of this constituent, what opens to them a new way of use
45

Valorisation des hémicelluloses de bois : synthèse de charges papetières / Hemicelluloses based fillers for papermaking industry

Belmokaddem, Fatima-Zohra 19 December 2011 (has links)
Résumé confidentiel / Résumé confidentiel
46

Modelling the viscoplastic properties of carbon black filled rubber : A finite strain material model suitable for Finite Element Analysis

Österlöf, Rickard January 2016 (has links)
An increased environmental awareness, legal demands and the large part of total costs attributable to fuel cost are all incentives for the automotive industry to reduce fuel consumption. The optimal driveline to enable this reduction depends on the operational conditions and the available infrastructure. Moreover, special care is needed when developing the driveline isolators, since the demands on noise, vibration and harshness (NVH) are the same regardless of driveline. To this end, computer aided calculations can be used in order to evaluate a large number of configurations. However, these calculations are only, at best, as good as the material models employed. In the foreseeable future, rubber with reinforcing fillers will be used in vibration isolators in order to obtain the desired properties of these components. However, the stiffness and damping of rubber with reinforcing fillers are highly non-linear functions, and the available material models in commercial software and in the literature are often insufficient. Therefore, a finite strain viscoplastic material model is derived in the time domain and implemented as a user defined material model in Abaqus Explicit. The model captures the strain amplitude and frequency dependency of the storage and loss modulus for a carbon black filled natural rubber. The model is accurate over a wide range of shear strain amplitudes and frequencies, 0.2-50 % and 0.5-20 Hz, respectively, using only 5 material parameters. In addition, the model correctly captures the response from bimodal excitations. The implementation in Abaqus Explicit enables component characteristics to be evaluated early in the development phase, with material parameters derived from simple test specimens. The improved accuracy of simulations of these components can aid engineers develop more optimized solutions faster than with conventional methods. / En ökad miljömedvetenhet, juridiska krav och den stora delen av de totala kostnaderna som kan hänföras till bränslekostnader är alla incitament för fordonsindustrin att minska bränsleförbrukningen. Den optimala drivlinan för att möjliggöra denna minskning beror på driftförhållanden och den tillgängliga infrastrukturen. Dessutom ställs höga krav på utvecklingen av drivlineisolatorer, eftersom kraven på buller och vibrationer (NVH) är desamma oavsett drivlina. För detta ändamål kan datorstödda beräkningar användas för att utvärdera ett stort antal konfigurationer. Dessa beräkningar är, i bästa fall, endast så bra som de använda materialmodellerna. Inom en överskådlig framtid kommer gummi med förstärkande fyllmedel användas i vibrationsisolatorer för att erhålla de önskade egenskaperna hos dessa komponenter. Men styvheten och dämpningen i gummi med förstärkande fyllmedel är kraftigt icke-linjära funktioner, och de tillgängliga materialmodellerna i kommersiella programvaror och i litteraturen är ofta otillräckliga. Därför är en viskoplastisk materialmodell för finita deformationer framtagen i tidsdomänen och implementeras som ett användardefinierat material i Abaqus Explicit. Modellen fångar töjningsamplitud- och frekvensberoendet av lagrings- och förlustmodulen för ett kimröksfyllt naturgummi. Den är korrekt över ett brett intervall av skjuvtöjningsamplituder och frekvenser, 0.2-50% respektive 0.5-20 Hz, och kräver endast 5 materialparametrar. Dessutom fångar modeller responsen från bimodala excitationer. Implementeringen i Abaqus Explicit gör att komponentegenskaper kan utvärderas tidigt i utvecklingsfasen, med materialparametrar som härrör från enkla provkroppar. Den förbättrade noggrannheten i simuleringar av dessa komponenter kan hjälpa ingenjörer att utveckla mer optimerade lösningar snabbare än med konventionella metoder. / <p>QC 20160406</p>
47

Structuration des charges dans des mélanges de polymères immiscibles / Selective localisation of fillers in immiscible polymer blends

Plattier-Boné, Julien 15 February 2013 (has links)
Le but de la thèse est de comprendre les mécanismes de localisation de particules (on parle de charges) dans des mélanges de polymères immiscibles. Ces travaux montrent que la localisation des charges de noir de carbone dans un mélange polypropylène (PP)/ poly-ε-caprolactone (PCL) est dominée par le rapport de viscosités et non par des paramètres thermodynamiques (liés au mouillage de la particule). La localisation des charges est expliquée par la compétition des forces de drainage visqueux s’exerçant sur les particules à l’interface. Le mécanisme de transfert des charges est mis en évidence par observation de la relaxation de gouttes de PCL chargées immergées dans une matrice PP. Le transfert se produit par un nouveau mécanisme, appelé « zip flow », qui consiste à l’érosion des gouttes au niveau des pointes. La maîtrise des différents paramètres étudiés permet de localiser les particules sélectivement à l’interface et d’obtenir des propriétés de conductivité à faible taux de charges. / The aim of this work is to understand mechanisms responsible for particles localisation in immiscible polymer blends. This study shows that carbon-black fillers localisation in polypropylene (PP)/ poly-ε-caprolactone (PCL) blends is strongly influenced by the viscosity ratio (rather than thermodynamic parameters through the wetting coefficient). The localisation of the fillers is explained by a competition of hydrodynamic forces applied on particles localised at the interface. The transfer of fillers is investigated at the droplet scale by observation of the relaxation of CB-filled PCL droplets suspended in PP matrix. CB particles are transferred from the PCL droplet to the PP matrix by a new mechanism, called “zip flow”, which involves the erosion of the droplet edges, leading to the extraction of particles localised there. The control of these parameters allows to localize fillers selectively at the interface and to reduce significantly the electrical percolation threshold.
48

Tribological Behaviour of Hybrid Carbon Filled UHMWPE Composites in Water

Vadivel, Hari Shankar January 2016 (has links)
There is a increasing emphasis in today’s world to use environmental friendly solutions for tribological and lubrication purposes. Use of water as a lubricant presents a cost effective and easy method of bio friendly lubrication. But, as water has low viscosity, it is necessary that the materials used in water lubricated contacts perform exceedingly well in boundary lubricated conditions. Polymer Based Materials (PBMs), are one such group of materials which have been proven to perform well in such conditions. In particular, Ultra High Molecular Weight Polyethylene (UHMWPE) has been extensively used in water lubricated contacts. But, PBMs still suffer from wear and related problems and there is room for improvement. Various methods have been tried with mixed results to improve the qualities of polymers and consequently their performance in water lubricated contacts. One such method is by inclusion of fillers. Conventionally, micron sized fillers have been used to form composites with a polymer resulting in materials with better properties. Recently, nanometer sized reinforcements have been attracting more attention due to their unique mechanical and tribological properties. Combining micrometer and nanometer sized filler in a polymer composite could help form materials with excellent properties. Such composites would be termed as a hybrid material. Therefore, the aim of this project and thesis is to experimentally investigate the influence and interaction of micro and nano carbon-based fillers on tribological behaviour of UHMWPE composites and provide further understanding of the mechanisms involved.
49

Vliv velikosti částic na lisovatelnost laktosy / The effect of particle size on lactose compressibility

Havlíková, Natálie January 2019 (has links)
Charles University in Prague, Faculty of Pharmacy in Hradci Králové Department of: Pharmaceutical technology Consultant: PharmDr. Pavel Ondrejček, Ph.D. Student: Natálie Havlíková Title of Thesis: The effect of particle size on lactose compressibility It is known that the particle size of the compressed material plays an important role in the manufacture of tablets. It affects the properties of intermediate and final products. In this thesis the properties of tablets made of two lactose types, which were used as model fillers, were studied. These were Tablettose® 80 and Lactopress® Anhydrous. In both lactose types, five sieved size fractions of the particle size ranging from 9 to 346µm and their original unsieved mixture were used. The compaction forces ranging from 2 to 10kN were used for tablet preparation. Magnesium stearate was used for external lubrication. The evaluation of the prepared tablets was done mainly by using the pharmacopoeial methods. The evaluated parameters were friability, disintegration time and hardness. Furthermore, the elasticity of the tablets and the evaluation using the force-displacement method parameters were assessed. From the results of this work, it is not possible to unambiguously determine the advantage of one particular fraction size in the comparison to the...
50

中文重覆語現象之研究 / A Study on the Repetition Phenomena in Mandarin Chinese

梁麗君, Liang, Li-chun Unknown Date (has links)
論文研究重點在探討言談中不具語型及語意功能的重覆語現象。 在理想而完全流暢的言談中,這些重覆語常被視為語誤現象。而此研究目的在於證明重覆語在自然言談中之存在為必要,同時並分析其形式以及在語言產製過程中其所扮演的角色。 文中重覆語研究的語料來自現代漢語即國語。形式研析結果顯示重覆 語主要發生於名詞片語及動詞片語上,而其出現長度範圍在一至八個音節,但以單音節重覆語出現最頻繁,而半數以上的重覆語緊接在原語詞之後出現。再者,這些重覆語在言談中可表現七種作用--填充語?修正語?強調語?修飾語?主題連串語?連續動作描述語?改述語。 重覆語的形式研究同時反映中文的構詞及文法特質,而其功能研究正 揭示此看似微不足道的語言現象背後所蘊含之語言產製機制及過程。 / The study focuses on the repetitions which serve no syntactic and semantic functions in speech. These repetitions, which seemingly appear to be deviant from the ideal delivery of normal speech, should be regarded as natural products generated in the process of speaking. The study tries to justify the existence of these repetitions in natural speech, to analyze their forms and to demonstrate the duties they take in speech production. The data of repetitions in the study come from utterances in Mandarin Chinese. They are analyzed and discussed formally and functionally. Formally speaking, these repetitions mainly belong to Noun Phrases and Verb Phrases, and their lengths range from one to eight syllables, with one-syllable repetitions occurring most frequently, and more than half of the total repetitions included in the data appear immediately after the original items. As to the functional aspect, they are found to serve to fill in the blank in speech, or to help speakers correct mistakes in utterances. Besides, repetitions can also play the roles of emphatic expressions, elaboration, overt topic chains, action continuation, or paraphrases. The result of the formal analysis of repetitions reflects the morphological and syntactic characteristics of Mandarin Chinese. And the functional analysis discloses the mechanism underlying these apparently insignificant occurrences of repetition.

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