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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.
121

Υλοποίηση και συγκριτική αξιολόγηση με βάση τα frameworks Ruby on rails

Βικτωράτος, Ιωσήφ 25 January 2010 (has links)
Η παρακάτω διπλωματική αφού κάνει μια εκτενή αναφορά στα είδη των γλωσσών προγραμματισμού επεκτείνεται και στην περιγραφή των frameworks που χρησιμοποιούνται σήμερα ευρέως. Έπειτα ασχολούμαστε εκτενώς με το framework ruby on rails και περιγράφουμε αναλυτικά τις δυνατότητες που μας προσφέρει μέσα από την ανάπτυξη κάποιων εφαρμογών. Ακριβέστερα, έχουν υλοποιηθεί και αξιολογηθεί ένα site με forum και shopping cart, ένα blog, μια wiki page και ένα site για δημιουργία προφίλ από τους χρήστες του. / The following work has made an extensive reference to the kinds of programming languages and then extends a description of the frameworks currently used widely. Then devotes considerable attention to the framework ruby on rails and describes in detail the possibilities offered by means of developing some applications. Being more specific, we implemented and evaluated a site with forum and shopping cart, a blog, a wiki page, and a site for creation profile of its users.
122

Waiting for power : affection, ethics and politics in the everyday life of popular Chile

Briceño, Pablo Agustin January 2018 (has links)
Based on fourteen months of ethnographic fieldwork in población ‘La Victoria’, a working-class neighbourhood in the city of Santiago, this research describes the everyday lives of its inhabitants (pobladores) in the context of contemporary neoliberal Chile. Although the pobladores’ movement had animated Chilean politics since the 1950s, also becoming the main actor in the struggle against the dictatorship, after the return to democracy in 1990 pobladores disappeared from the political arena. Most researchers have proposed that the political absence of pobladores must be understood as an effect of neoliberal modernization – a set of policies implemented during dictatorship and maintained by successive democratic governments after 1990. Their main argument is that a major cultural transformation in Chile has degraded social ties producing a consumeristic, individualistic and depoliticized society. Instead, I propose that pobladores from La Victoria have, despite the transformations, preserved a form of conviviality based on strong affective bonds with kin, friends and neighbours – alongside equally sentimental separations and divisions from others. I argue that, due to their pervasiveness and importance in pobladores’ lives, social relationships are the main agents in the articulation of pobladores’ ethical frameworks guiding their decisions and actions in life. Pobladores’ affective social relationships have allowed them not only to mitigate the side effects of the current neoliberal model, but also to accept, adapt and contest specific aspects of it. In this sense, life in the población has a heterogeneous grammar, a way in which social relations are articulated and disarticulated, activated and de-activated, connecting personal lives to collective processes. This grammar of strong affective ties, terrible betrayals and deep but changing separations and divisions is what I call the ‘politics of the everyday life’. This politics of everyday life lies behind apparently very different historical processes, such as the pobladores’ struggle against dictatorship in the 1980s and their post-1990 absence from the political arena. I contend that what characterizes the current context is not a lack of politics or a ‘depoliticization’ but a particular way in which certain pobladores, known as ‘políticos’ – those interested in collective action in order to produce change in the world – are articulated with or disarticulated from other pobladores in the politics of everyday life in the población.
123

In silico design of metal organic frameworks for greenhouse gas capture

Amrouche, Hedi January 2011 (has links)
The present thesis proposes to explore the potential of Zeolitic Imidazolate Framework ZIFs for CO2 capture applications in the conditions required by the Pressure Swing Adsorption separations process. Molecular modelling methods, combining Monte Carlo, Density Functional Theory and ab-initio simulations, were employed to mimic pure and mixture gas adsorption in ZIF materials. A transferable Force Field specifically developed for ZIFs materials is used to characterize a large variety of frameworks. Theses studies enable us to better understand the phenomena acting during adsorption process. Thereby several innovative modifications are proposed to enhance the ZIFs properties for CO2 capture and a series of hypothetical ZIFs are designed, characterized and compared to existing materials. The results cumulated during this thesis were then summarized to propose a first correlative model able to predict ZIF properties from a set of solids descriptors. This study enables to guide the structure design to optimize the ZIF properties.
124

Metal Ion Detection by Luminescent Metal Organic Frameworks

January 2018 (has links)
abstract: Metal Organic Frameworks(MOFs) have been used in various applications, including sensors. The unique crystalline structure of MOFs in addition to controllability of their pore size and their intake selectivity makes them a promising method of detection. Detection of metal ions in water using a binary mixture of luminescent MOFs has been reported. 3 MOFs(ZrPDA, UiO-66 and UiO-66-NH2) as detectors and 4 metal ions(Pb2+, Ni2+, Ba2+ and Cu2+) as the target species were chosen based on cost, water stability, application and end goals. It is possible to detect metal ions such as Pb2+ at concentrations at low as 0.005 molar using MOFs. Also, based on the luminescence responses, a method of distinguishing between similar metal ions has been proposed. It is shown that using a mixture of MOFs with dierent reaction to metal ions can lead to unique and specic 3D luminescence maps, which can be used to identify the present metal ions in water and their amount. In addition to the response of a single MOF to addition of a single metal ion, luminescence response of ZrPDA + UiO-66 mixture to increasing concentration of each of 4 metal ions was studied, and summarized. A new peak is observed in the mixture, that did not exist before, and it is proposed that this peak requires metal ions to activate / Dissertation/Thesis / Masters Thesis Materials Science and Engineering 2018
125

Estudo sobre a evolução do comércio e WEB pessoal ao comércio social: características, marcos e tecnologias

CARVALHO, Emmanuel Barreto de 31 January 2011 (has links)
Made available in DSpace on 2014-06-12T16:00:57Z (GMT). No. of bitstreams: 2 arquivo7094_1.pdf: 3842732 bytes, checksum: 3ccd5ae3a7fc06249731bdcbbd36426b (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2011 / Faculdade de Amparo à Ciência e Tecnologia do Estado de Pernambuco / Atualmente é observada uma mudança de paradigma na comunicação, no relacionamento e no modo de fazer negócio. O comércio, como o conhecemos, evoluiu para o comércio eletrônico e suas generalizações, assim como, a Web pessoal para comunidades virtuais também evoluiu para redes sociais. Sendo assim, é importante entender como o desenvolvimento nessas áreas está acontecendo, quem são os principais atores, qual influência as eras da Web têm na escolha de características e requisitos para classificar cada elemento contemporâneo, nesse domínio. O objetivo, dessa dissertação é agregar estudos relevantes que definem como as redes sociais oferecem suporte para as necessidades de seus participantes, em relação ao comércio eletrônico. Para alcançar esse objetivo, foi executado um Mapeamento Sistemático da Literatura de Redes Sociais e Comércio Eletrônico em Engenharia de Software. Baseado em buscas realizadas em mecanismos automatizados e buscas manuais em conferências importantes nas área de redes sociais e comércio eletrônico, um total de 1078 estudos foram obtidos. Trinta e dois estudos primários foram identificados como relevantes e classificados de acordo com quatro questões de pesquisa. A partir da análise realizada, o estudo inferiu, que uma nova forma de interação social existe entre as redes sociais e o comércio eletrônico, o qual converge para o comércio social, que é benéfico em vários cenários. As significativas e Importantes contribuições desse trabalho são: fornecer informações relevantes à aqueles que desejem desenvolver o comércio social, reduzir o tempo necessário para uma tecnologia ser amplamente utilizada e ainda disseminar o conceito pela comunidade
126

Design Principles for Reusable, Composable and extensible Frameworks

Gurp, Jilles van January 1999 (has links)
Frameworks have been used since the early eighties. Now that frameworks are becoming increasingly popular, several problems are surfacing. Those problems can be categorized into evolution problems (i.e. problems with changes over time) and composition problems (i.e. problems that occur when more than one framework is used in an application). This master thesis focusses on preventing these problems in an early stage in the development of a framework. Guidelines for building OO Frameworks are presented and the guidelines are tried out in the domain of communication protocols.
127

Robust Machine Learning QSPR Models for Recognizing High Performing MOFs for Pre-Combustion Carbon Capture and Using Molecular Simulation to Study Adsorption of Water and Gases in Novel MOFs

Dureckova, Hana January 2018 (has links)
Metal organic frameworks (MOFs) are a class of nanoporous materials composed through self-assembly of inorganic and organic structural building units (SBUs). MOFs show great promise for many applications due to their record-breaking internal surface areas and tunable pore chemistry. This thesis work focuses on gas separation applications of MOFs in the context of carbon capture and storage (CCS) technologies. CCS technologies are expected to play a key role in the mitigation of anthropogenic CO2 emissions in the near future. In the first part of the thesis, robust machine learning quantitative structure-property relationship (QSPR) models are developed to predict CO2 working capacity and CO2/H2 selectivity for pre-combustion carbon capture using the most topologically diverse database of hypothetical MOF structures constructed to date (358,400 MOFs, 1166 network topologies). The support vector regression (SVR) models are developed on a training set of 35,840 MOFs (10% of the database) and validated on the remaining 322,560 MOFs. The most accurate models for CO2 working capacities (R2 = 0.944) and CO2/H2 selectivities (R2 = 0.876) are built from a combination of six geometric descriptors and three novel y-range normalized atomic-property-weighted radial distribution function (AP-RDF) descriptors. 309 common MOFs are identified between the grand canonical Monte Carlo (GCMC) calculated and SVR-predicted top-1000 high-performing MOFs ranked according to a normalized adsorbent performance score. This work shows that SVR models can indeed account for the topological diversity exhibited by MOFs. In the second project of this thesis, computational simulations are performed on a MOF, CALF-20, to examine its chemical and physical properties which are linked to its exceptional water-resisting ability. We predict the atomic positions in the crystal structure of the bulk phase of CALF-20, for which only a powder X-ray diffraction pattern is available, from a single crystal X-ray diffraction pattern of a metastable phase of CALF-20. Using the predicted CALF-20 structure, we simulate adsorption isotherms of CO2 and N2 under dry and humid conditions which are in excellent agreement with experiment. Snapshots of the CALF-20 undergoing water sorption simulations reveal that water molecules in a given pore adsorb and desorb together due to hydrogen bonding. Binding sites and binding energies of CO2 and water in CALF-20 show that the preferential CO2 uptake at low relative humidities is driven by the stronger binding energy of CO2 in the MOF, and the sharp increase in water uptake at higher relative humidities is driven by the strong intermolecular interactions between water. In the third project of this thesis, we use computational simulations to investigate the effects of residual solvent on Ni-BPM’s CH4 and N2 adsorption properties. Single crystal X-ray diffraction data shows that there are two sets of positions (Set 1 and 2) that can be occupied by the 10 residual DMSO molecules in the Ni-BPM framework. GCMC simulations of CH4 and N2 uptake in Ni-BPM reveal that CH4 uptake is in closest agreement with experiment when the 10 DMSO’s are placed among the two sets of positions in equal ratio (Mixed Set). Severe under-prediction and over-prediction of CH4 uptake are observed when the DMSO’s are placed in Set1 and Set 2 positions, respectively. Through binding site analysis, the CH4 binding sites within the Ni-BPM framework are found to overlap with the Set 1 DMSO positions but not with the Set 2 DMSO positions which explains the deviations in CH4 uptake observed for these cases. Binding energy calculations reveal that CH4 molecules are most stabilized when the DMSO’s are in the Mixed Set of positions.
128

Structural behaviour and adsorption properties of Sc-based metal-organic frameworks

Sotelo, Jorge January 2016 (has links)
Some of the challenges faced when developing novel functional materials, cannot be resolved without the correct understanding of their structure‐property relationships. Metal‐organic frameworks (MOFs) constitute a representative example where in-depth structural knowledge can greatly help improve and optimise their application into industrially relevant settings. Fortunately, the inherent crystalline nature of MOFs allows for analysis using the wide range of crystallographic experimental techniques that are currently available. This work covers the study of the structural properties of a particular family of MOFs, which have shown significant potential as molecular sieves and for gas storage. Sc-based MOFs first attracted attention for their particularly robust and inert nature, bypassing some of the physical challenges many MOFs have when undergoing industrial implementation. After an initial review of the state of the art in the field of MOFs and the techniques utilised to analyse their properties, this work then focuses on the mechanical properties of a series of functionalised and unfunctionalised Sc‐dicarboxylate MOFs. Using nano‐indentation techniques and high‐pressure crystallography, the hardness and elasticity of these materials are correlated to their different structural features, confirming their relative robustness when compared to other MOFs in the literature. An interesting property of Sc2BDC3 is its selective uptake of CO2 over other fuel-related gases such as CH4 and CO. In this context, the in situ adsorption crystallographic analysis of Sc2BDC3 and its amino‐functionalised derivative Sc2(BDC‐NH2)3 (BDC‐NH2 = 1,4‐amino‐2‐benzenedicarboxylate) is described, as performed using the gas cell set up of beamline I19 at the Diamond Light Source synchrotron. This study is the first example of a mixed gas atmosphere experiment using single‐crystal diffraction, which in conjunction with in silico, adsorption and breakthrough experiments, provides direct insight into the interactions that drive the selective behaviour of both frameworks. Following this, the MOF Sc2BDC3 (BDC = 1,4‐benzenedicarboxylate), is selected as a case study for branched and unbranched alkane separation. Here, high‐pressure crystallography shows how these relatively oversized guest molecules, can be forced at thousands of atmospheres of pressure inside the narrow triangular channels (< 4 Å diameter) of the framework. It is also possible to resolve the structural changes the framework undergoes upon uptake of the different guests, as well as locate the adsorption sites of the hydrocarbons in the pores of Sc2BDC3, which can be then correlated to the gas adsorption behaviour of the different guests. To conclude, the high‐pressure inclusion study of both CO2 and CH4 inside Sc2BDC3 shows how combining cryoloading techniques and molecular crystallography for the first time, can provide improved models of the adsorbed gaseous guests inside Sc2BDC3. This example not only provides a novel alternative in which to study more easily the adsorption sites in MOFs via diffraction techniques, but also reveals some of the interesting structural behaviour MOFs can have in these extreme conditions.
129

Evaluation of JavaScript frameworks : Why should you use them?

Hjelm, Sofia January 2015 (has links)
JavaScript is today’s most common client-side programming language for the web. Choosing the most adapted framework for each and every project can optimize the development process and increase profits. Developers often lack knowledge about what to prioritize when choosing a framework and very little previous research regarding this subject area is available. This thesis investigates two JavaScript client-side frameworks and answers the questions of why you should use a framework when developing applications. This thesis also investigates why a company should develop a new framework, when equivalent open-source alternatives are available. To be able to answer the questions interviews with developers were conducted. The results are that using a framework can optimize the development process regarding time and complexity, but learning a new framework can be difficult. In rare cases it is a great idea to develop a new framework for a certain project, but it is often not worth it. Developers also seem to choose experience of using a framework over performance.
130

Electrospinning of porous composite materials for hydrogen storage application

Annamalai, Perushini January 2016 (has links)
>Magister Scientiae - MSc / Due to the rapid depletion of fossil fuel reserves and the production of environmentally harmful by-products such as carbon dioxide, there is an urgent need for alternate sustainable clean energy. One of the leading candidates in this endeavour is hydrogen, which can be used as an energy carrier since it has a high energy density, zero emissions and is produced from non-depletable resources such as water. The major challenge hindering a hydrogen economy is the lack of safe and effective storage technologies for mobile applications. A prospective solution to this problem lies in the use of porous powdered materials, which adsorb the hydrogen gas. However, the integration of these powdered materials into a storage tank system, results in the pipelines being contaminated during filling cycles. This necessitates the shaping of the porous powdered materials. Among the many shaping techniques available, the electrospinning technique has been proposed as a promising technology since it is a versatile process that is easily scaled-up making it attractive for the applications of the study. Furthermore, the electrospinning process enables the synthesis of nano-sized fibres with attractive hydrogen sorption characteristics. In this regard, the current study employs the electrospinning technique to synthesise electrospun composite fibres for mobile hydrogen storage applications. After electrospinning three polymers, polyacrylonitrile (PAN) was selected as the most suitable polymer because it yielded bead-free electrospun fibres. However, the diameter of the PAN fibres was large/thick which prompted further optimisation of the electrospinning parameters. The optimised electrospinning conditions that yield unbeaded fibres within the desired diameter range (of 300-500 nm) were a PAN concentration of 10 wt%, a flow rate of 0.4 mL/h, a distance of 10 cm between the needle tip and collector plate, and an applied voltage of 8 kV. The study then progressed to the synthesis and characterisation of the pristine porous powdered materials which adsorb hydrogen gas. The porous powdered materials investigated were commercial zeolite 13X, its synthesised templated carbon derivative (ZTC) and Zr (UiO-66) and Cr (MIL-101) based metal-organic frameworks (MOFs). ZTC was synthesised via liquid impregnation coupled with chemical vapour deposition (CVD), and the MOFs were synthesised by the modulated solvothermal method. Analysis of the ZTCs morphology and phase crystallinity show that the carbon templated process using zeolites was successful, however, ZTC was amorphous compared to crystalline zeolite template. The BET surface area was assessed with the aid of nitrogen sorption isotherms for both zeolite 13X and ZTC, and values of 730 and 2717 m²/g, respectively were obtained. The hydrogen adsorption capacity for zeolite 13X was 1.6 wt% and increased to 2.4 wt% in the ZTC material at 77 K and 1 bar. The successful synthesis of well defined, crystalline MOFs was evident from X-ray diffraction and morphological analysis. The BET surface area and hydrogen adsorption for Zr MOF were 1186 m²/g and 1.5 wt%, respectively at 77 K and 1 bar. Cr MOF had a BET surface area of 2618 m²/g and hydrogen adsorption capacity of 1.9 wt% at 77 K and 1 bar. The main focus of the study was to synthesise electrospun composite fibres that can adsorb hydrogen gas and thus provide significant insight in this field of research. As such it examined composite fibres that incorporates porous powdered materials such as zeolite 13X, ZTCs, UiO-66 (Zr) MOF and MIL-101 (Cr) MOF and investigated their ability to adsorb hydrogen gas, which have not been reported previously. The synthesis of composite fibres was achieved by incorporating the porous powdered materials into the PAN resulting in a polymeric blend that was then electrospun. Morphological analysis illustrated that the porous powdered materials were successfully supported by or incorporated within the PAN fibres, forming composite fibres. The BET surface area of the 40 wt% zeolite-PAN and 12.5 wt% ZTC-PAN composite fibres were 440 and 1787 m²/g respectively. Zr MOF and Cr MOF composite fibres had a BET surface area of 815 and 1134 m²/g, respectively. The BET surface area had reduced by 40, 34, 31 and 57% for zeolite 13X, ZTC, Zr MOF and Cr MOF, respectively after these porous powdered materials were incorporated into PAN. The hydrogen adoption capacity for 40 wt% zeolite-PAN, 12.5 wt% ZTC-PAN, 20 wt% Zr MOFPAN and 20 wt% Cr MOF-PAN composite fibres was 0.8, 1.8, 0.9 and 1.1 wt%, respectively. This decrease was attributed to the limited amount of porous powdered materials that could be incorporated into the fibres since only 40 wt% of zeolite 13X, 12.5 wt% of ZTC and 20 wt% of the MOFs were loaded into their respective composite fibres. This was due to the fact that incorporation of greater amounts of porous powdered materials resulted in a viscous polymeric blend that was unable to be electrospun. It is evident from the study that electrospinning is a versatile process that is able to produce composite fibres with promising properties that can potentially advance the research in this field thus providing a practical solution to the problem of integrating loose powdered materials into an on-board hydrogen storage system. / CSIR Young Researchers Establishment Fund (YREF)

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