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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.
471

Assessing the impact of micro-lending programmes in the informal sector in Cape Town. A case study, The Nations Trust Organization

Ibrahim, Sabir. M. January 2003 (has links)
Magister Artium (Development Studies) - MA(DVS) / The promotion of widespread entrepreneurship through the setting up of small and medium sized enterprises (SMMEs ) is crucial for the transformation to a market economy and the democratisation of society in \the new South Africa. SMMEs are recognized as an engine of economic \ \growth and a source of sustainable development. Within this sector micro , 1nd small enterprises are of special importance because they are considered as the cradle of entrepreneurship, particularly in environments facing high ketllPIQYII'1:en!and poverty,. as j!) the case ~~.South Africg,
472

INVESTIGATION OF THE STATIC AND DYNAMIC BEHAVIOR OF A MICRO MIRROR

Ilyas, Saad 11 1900 (has links)
This dissertation presents the modeling, design, fabrication, and experimental testing of a polyimide based micro mirror for applications in MEMS logic devices based on its static behavior and in MEMS resonators using mixed frequency excitation. First, a universal MEMS logic device that can perform all the logic operations, such as INVERTER, AND, NAND, NOR, and OR gates using one physical structure, within an operating range of 0-10 volts. It can also perform XOR and XNOR with one access inverter using the same structure with different electrical interconnects. We discuss the fabrication, simulations and experimental results demonstrating these logic operations on a polyimide micro mirror. The device is capable of performing the switching operation with a frequency of 1 kHz, a switching time of 8.2 μs, and an electrical lifetime of 8000 cycles. Second, this study presents an experimental and theoretical investigation of a micro mirror under a mixed frequency signal composed of two harmonic AC sources. The experimental and theoretical dynamics are explored via frequency sweeps in the desired neighborhoods. One frequency is fixed while the other frequency is swept through a wide 5 range to study the dynamic responses of the micro mirror. These responses are studied under different frequencies and different input voltages. The results show interesting dynamics, where the system exhibits primary resonance, and combination resonances of additive and subtractive type. The mixed excitation is demonstrated as a way to increase the bandwidth of the resonator near primary resonance, which can be promising for resonant sensing applications in the effort to increase the signal-noise ratio over extended frequency range. It can be promising for energy harvesting as well; since it provides the system with resonances of very high amplitudes at very low frequencies regardless of what is the natural frequency of the system, however this still needs further investigation.
473

Label Free Micro-RNA Biomarker Detection in Serum Samples for Potential Diagnosis Application at Point-of-Care Settings

Pokharel, Rounak January 2020 (has links)
The number of new cancer cases is projected to rise to 23.6 million by 2030 according to the National Cancer Institute. Obesity & cardiovascular diseases are among the leading causes of death worldwide according to recent reports. Biomarkers— any molecules found within a human body that can be used to monitor an individual's health — have been shown to play a significant role in the detection of cancer, obesity, and cardiovascular diseases. Recent studies have shown that in the diagnosis and screening of various human diseases, including cancer, obesity and cardiovascular diseases, circulating microRNAs (miRNAs) are important biomarkers. A crucial roadblock to using microRNA in screening applications is the lack of effective and low-cost microRNA detection. To address this issue, in this study, we have developed a viable method that combines the dielectrophoresis and electrical impedance. Results show this approach can measure very small concentrations of label-free microRNAs (1pM).
474

Evaluación de protecciones adaptativas para una micro-red

Moreno Arancibia, Gustavo Alejandro January 2017 (has links)
Ingeniero Civil Eléctrico / En la Facultad de Ciencias Físicas y Matemáticas (FCFM), Universidad de Chile-Santiago de chile, en el cuarto piso del Departamento de Ingeniería Eléctrica (DIE) se encuentra el Laboratorio de Energía y Accionamiento. En este laboratorio hay una red eléctrica que se utiliza con fines docentes en diversos cursos del DIE. Uno de estos cursos exige que el sistema de protecciones opere de forma coordinada (mientras la red simula ser una Micro-Red), sin embargo, actualmente esta red no cuenta con los equipos y dispositivos necesarios para este fin. De esta forma se pretende implementar un esquema de protecciones Look up Table adaptivo en esta red. Bajo este contexto surge la necesidad de determinar las distintas curvas de protecciones necesarias en cada dispositivo de protección, para que de esta forma se pueda contar con estas configuraciones al momento de implementar este esquema de protecciones adaptivo en el laboratorio. Para poder obtener los resultados se empleó el uso del software Power Factory Digsilent. En dicho software se construyó la red del laboratorio junto a los elementos que tendrá esta una vez que se encuentre operando como Micro-red. Se realizaron estudios de corrientes de fallas en las diversas topologías que se puedan presentar. De esta forma se obtuvo la curva necesaria en cada estado de operación (topología de la red) para cada dispositivo de protección. Además se realizó una comparación de desempeño con un esquema tradicional fijo configurado solamente con respecto a la red externa. Entre las principales conclusiones se puede mencionar que una estrategia adaptativa con protecciones de curvas ajustables tiene un mejor desempeño que un esquema tradicional con dispositivos de ajuste fijo. Por otro lado sólo es necesario coordinar los dispositivos con respecto a aquellas barras que poseen elementos capaces de imponer frecuencia y tensión y que al haber generación distribuida se forman distintos caminos de coordinación , por lo que se deben implementar dispositivos direccionales.
475

The perceptions and understanding of the importance and the use of marketing communications by microenterprises in South Africa

Mokgoatlheng, Sipho 23 February 2013 (has links)
This study examined marketing communications in South African microenterprises. Large organisations normally engaged in marketing activities to support their growth and success. With microenterprises, a type of small business, touted as having a critical role to play in the development of South Africa’s economy but failing to live up to that expectations the purpose of this study was to explore and gain a preliminary understanding of the perceptions and understanding of the importance and the use of marketing communications by microenterprises in South Africa.Micro-entrepreneurs around Gauteng were identified as the population to be studied and from that population, micro-entrepreneurs who work with MEDO were identified as a sample. Using a questionnaire, data was collected from owners of microenterprises and analysed to arrive to findings outlined below:An overwhelming majority of the owners of microenterprises have a positive perception towards marketing communications. They believe it can play a vital role in the growth and success of their businesses. However, it was interesting to note that again a majority of them did not understand the concept of marketing communications. What was also interesting was that they were prepared to learn more about the concept because they believe it can make a difference to their businesses. / Dissertation (MBA)--University of Pretoria, 2012. / Gordon Institute of Business Science (GIBS) / unrestricted
476

Time decomposition methods for optimal management of energy storage under stochasticity / Méthodes de décomposition temporelle pour la gestion optimale de stockages énergétiques sous incertitudes

Rigaut, Tristan 16 May 2019 (has links)
L'évolution du stockage d'énergie permet de développer des méthodes innovantes de gestion de l'énergie à une échelle locale. Les micro réseaux électriques sont une forme émergente de petits réseaux électriques munis de production locale, de stockage d'énergie et en particulier d'un système de gestion de l'énergie (EMS pour Energy Management System). De nombreuses études et recherches scientifiques ont été menées pour proposer diverses stratégies d'implémentation de ces EMS. Néanmoins il n'existe pas à ce jour d'articulation claire et formelle de ces méthodes permettant leur comparaison. L'une des principales difficultés pour les EMS, est la gestion des dynamiques des différents systèmes énergétiques. Les variations de courant vont à la vitesse de l'électron, la production d'énergie solaire photovoltaïque varie au gré des nuages et différentes technologies de stockages peuvent réagir plus ou moins vites à ces phénomènes imprévisibles. Nous étudions dans ce manuscrit, un formalisme mathématique et des algorithmes basés sur la théorie de l'optimisation stochastique multi-étapes et la Programmation Dynamique. Ce formalisme permet de modéliser et de résoudre des problèmes de décisions inter-temporelles en présence d'incertitudes, à l'aide de méthodes de décomposition temporelle que nous appliquons à des problèmes de gestion de l'énergie. Dans la première partie de cette thèse, "Contributions à la décomposition temporelle en optimisation stochastique multi-étapes", nous présentons le formalisme général que nous utilisons pour décomposer en temps les problèmes d'optimisation stochastique avec un grand nombre de pas de temps. Nous classifions ensuite différentes méthodes de contrôle optimal au sein de ce formalisme. Dans la seconde partie, "Optimisation stochastique de stockage d'énergie pour la gestion des micro réseaux", nous comparons différentes méthodes, introduites dans la première partie, sur des cas réels. Dans un premier temps, nous contrôlons une batterie ainsi que des ventilations dans une station de métro récupérant de l'énergie de freinage des trains, en comparant quatre algorithmes différents. Dans un second temps, nous montrons comment ces algorithmes pourraient être implémentés sur un système réel à l'aide d'une architecture de contrôle hiérarchique de micro réseaux électrique en courant continu. Le micro réseaux étudié connecte cette fois ci de l'énergie photovoltaïque à une batterie, une super-capacité et à une charge électrique. Enfin nous appliquons le formalisme de décomposition par blocs temporels présenté dans la première partie pour traiter un problème de gestion de charge de batterie mais aussi de son vieillissement long terme. Ce dernier chapitre introduit 2 algorithmes basés sur la décomposition par blocs temporels qui pourraient être utilisés pour le contrôle hiérarchique de micro réseaux ou les problèmes d'optimisation stochastique présentant un grand nombre de pas de temps. Dans la troisième et dernière partie, "Logiciels et expériences", nous présentons DynOpt.jl un paquet développé en langage Julia qui a permis de développer toutes les applications de cette thèse et bien d'autres. Nous étudions enfin l'utilisation de ce paquet dans un cas de pilotage réel de système énergétique : la gestion intelligente de la température dans une maison de l'équipement Sense City / The development of energy storage paves the way to innovative methods to manage energy at a local scale. Micro grids are a novel kind of electrical grids with local production (renewable and waste energy), local demand, local storage and an Energy Management System (EMS). A wide literature already studies EMS implementations in micro grids but the produced methods are not exhaustively framed and compared. One of the main difficulty in micro grids energy management is to handle the different dynamics of electrical devices. Current variations are lighting fast, solar power changes quickly, different kind of storage react at different paces and batteries ageing is a slow process. We studya mathematical framework and algorithms, based on multistage stochastic optimization theory and Dynamic Programming, to model and solve energy management problems in micro grids with time decomposition methods. In the first part of this thesis, Contributions to time decomposition in multistage stochastic optimization, we present a general framework to decompose temporally large scale stochastic optimization problems into smaller subproblems. We then classify multiple existing resolution methods inside this framework. In the second part, Stochastic optimization of energy storage for management of micro grids, we compare different methods presented in the first part on realistic applications. First we control a battery and a ventilation in a subway station recovering subways braking energy with four different algorithms. Then we present how these results could be implemented on a real micro grid. We implement a fast online control method to stabilize the voltage in a simulated islanded DC micro grid connecting solar panels, an electrical load and two sorts of energy storage: a battery and a supercapacitor. Finally we apply our time decomposition framework to a problem of long term aging and energy management of a storage in a micro grid. This last chapter introduces a framework to model time decomposition of micro grids hierarchical control architectures, as well as two algorithms to solve temporally large scale stochastic optimization problems.In the third part, Softwares and experimentations, we present DynOpt.jl, a Julia language package developed to produce all the results of this thesis and more. Then we study an application of this software to the control of a real test bed: the energy aware temperature regulation of a real house in the equipment named "Sense City"
477

Craniofacial Bone Density is Regulated by Thyroid Hormone in Zebrafish:

May, Catherine M. January 2019 (has links)
Thesis advisor: Sarah McMenamin / Thyroid hormone (TH) facilitates developmental transitions, particularly by modulating cell proliferation and differentiation. Its role in regulating skeletal growth is well documented. Previous work from our lab and others have demonstrated that hypo- and hyperthyroid fish display changes in bone shape, ossification and the timing of ossification5. Zebrafish (Danio rerio) develop bone quickly, grow indefinitely throughout their lives, are highly amenable for imaging, and are a valuable model for skeletal biology research. Using Danio rerio, we sought to study the long-term effects of TH on bone density by rearing and comparing normal euthyroid (Eu) with a transgenically thyroid-ablated hypothyroid (TH-) and mutant hyperthyroid (TH+) fish. We found that TH strongly affects bone density and volume. We further hypothesize that TH is critical for the timing and fidelity of skeletogenesis. In hormone-dysregulated fish, we found that massive bone and cartilage exostoses grow on the dentary. Thyroid hormone’s effects are highly bone-specific: in TH- fish, we see reduced density in many craniofacial bones, but also increased volume and mineralization in other regions of the dentary. These data suggest that TH plays a critical role in coordinating bone mineralization with growth. / Thesis (MS) — Boston College, 2019. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Biology.
478

Micromobile

Runkvist, Adils January 2015 (has links)
I have designed and built a small home for myself that is movable by a bicycle. The structure is thought to fit in different places such as in a park, on a street or in the nature. I have been living in the structure for a short period of time, trying it out in different places around Stockholm. I want to understand the consequences of living minimal, to get the whole experience from an idea to the final result. What are the the ingredients of a home today beyond the absolute need of protection? / Jag har ritat och byggt en mobil strucktur som är flyttbar med en cykel. Jag har bott i strukturen en period runt om i Stockholm, för att testa hur självständigt det går att bo och på vilka platser det går att bo. Projektet handlar också om hemmet idag, hur kan det fungera och se ut?
479

Energy model based on fluvial rainfall for the rural population with torrential rain

Perales, Javier, Zapata, Gianpierre, Raymundo, Carlos 01 January 2019 (has links)
El texto completo de este trabajo no está disponible en el Repositorio Académico UPC por restricciones de la casa editorial donde ha sido publicado. / In Latin America, the lack of electricity has been a serious problem for over several years. To overcome this lack of supply in electricity supply, hydraulic energy is now being used in a greater proportion to fulfill the electricity needs in the rural areas. Investigations have been conducted to assess the environmental conditions of these rural areas to optimize the functionality of turbines used for hydraulic energy generation. However, there are very few focused on turbines of less than 0.5 kW generation. The proposed study aims to analyze the positioning of the blades of the cross-flow turbines and designing an electric generation system for rural dwellings. A simulation of each evaluated design was performed, and the power generated from these turbines was calculated. The results show that the power outputs initially were high and stabilized at a value of approximately 180 W, hence satisfying the minimum demands of a rural house.
480

Micro, small medium enterprise (MSMEs) and financial inclusion in Zambia

Masialeti, Nalumino 28 February 2022 (has links)
This study investigated Zambia's current financial inclusion state with specific reference to micro, small and medium enterprises (MSMEs). It also sought to determine the relationship between the age of the owner of MSME, size, literacy, gender, age, the period of operations, asymmetrical information, and financial inclusion in Zambia. The data collected from 70 respondents comprising MSMEs owners were analysed using multiple regression, correlation analysis and descriptive statistics. The research employed dependent variables, notably access, availability, and financial services, as the dependent variable. In contrast, independent variables included the size of MSME, literacy level, income level of the owner of MSME, the period of operations and asymmetrical information. On the one hand, the empirical findings indicate a positive relationship between usage and availability of financial services, and 'MSME's age of owner, size, literacy, gender, age, operation period, asymmetrical information in Zambia. On the other hand, findings, however, also show a negative relationship between gender and financial inclusion access. Whilst a positive relationship with the remaining independent variables. Accordingly, the study concluded that financial inclusion is evident in Zambia among MSMEs. However, the primary issue is that most MSMEs do not have access to formal funding from formal financial institutions. Therefore, the study calls for policies to be put in place to help MSMEs have access to formal financing. In addition, it also proposes formalising 'women's informal sector, financial literacy roadshows for women in the informal sector, training women in digital skills to enable them to have better access to financial services and giving financial institutions targets to onboard women-led MSMEs.

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