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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

Design and Fabrication of Micro Scratch Drive Actuator

Lin, Chung-ying 21 July 2006 (has links)
This thesis presents a surface micromachining process to fabricate scratch drive actuator (SDA). Besides, various parameters (plate length, plate width, plate shapes, support beam width, spring type, one-plate SDA/four-plate SDA, dimple number, bushing length and etching hole¡Ketc.) have been designed to find appropriate design parameters of the SDA and to reduce the driving-voltage. According to the results, we can demonstrate three points below: (i) Adding etching holes at the end of plate can reduce residual electric charge and increase life time of SDA. (ii) Changing normal wafer for low resistance wafer can reduce the driving-voltage of SDA about 35%. (iii) The life time of triangle SDA is longer than those of other plate shapes. Finally, discussions and suggestions for the design of SDA are presented in this thesis.
2

Design and Fabrication of SDA-based Micromotor

Chan, Chih-Hsien 02 September 2010 (has links)
This thesis presents three kinds of novel structural design of SDA-based micromotors(£g-motors), including out-side cover structure, flange cover structure and flange rib structure. In order to verify the feasibility of these structures, the device is fabricated by MUMPs micro-electro-mechanical system (MEMS) foundry. According to the experimental results, SDA £g-motor of flange cover structure is comparatively more ideal than the other structures. The ideal structure operates at 100 Hz when the voltage is added to 75 Vop, which results in resonant vibration on the SDA plate, and begins to rotate when the voltage reaches 100 Vop. The secondary goal of this thesis is using SDA £g-motor of flange cover structure to build surface micromachining process integration. The fabrication processes include eight photolithography masks, and the total fabrication procedure takes 62 steps. According to the experimental result, the device is made and succeeded or not, except that receiving the alignment technology influences, etching phosphorus silicon glass to define anchor is also an important process. Though processing technology of SDA £g-motor researched and developed by Taiwan has not reached high yield yet, but intact process module develop and integration has already appeared specifically through the research of this thesis.
3

The Simulation and Design of Scratch Drive Actuator for Micro Motor Application

Chen, Kuan-ming 28 July 2006 (has links)
This thesis presents the design of a scratch drive actuator (SDA) for Micro Motor Application. In accordance with the force needed to drive the mechanism, the relationship among SDA output force, geometries, and applied voltage is first constructed by employing the principle of virtual work. Having selected the topology of the device, the equations governing the motions and the forces of the micro motor and the actuator can be derived. The SDA and the associated micro motor mechanism are designed by considering the characteristics of Multi-User MEMS Processes, or MUMPs fabrication process. There are several types of SDA used for step motor application being designed and fabricated as illustrative samples. The chip well defined in MUMPs is released by immersing the chip in a bath of HF. It is followed by cleaning in DI water and IPA on a hot plate at 150¢J to reduce stiction.¡@The samples are inspected by OM and SEM, respectively.¡@The experimental and analytical results indicate the practicability of the proposed design concept.
4

[pt] AVALIAÇÃO DE ESTRATÉGIAS ANALÍTICAS PARA A DETERMINAÇÃO ELEMENTAR EM BIODIESEL POR ESPECTROMETRIA DE EMISSÃO ÓPTICA COM PLASMA INDUTIVAMENTE ACOPLADO (ICP OES) / [en] EVALUATION OF ANALYTICAL STRATEGIES FOR ELEMENTAL DETERMINATION IN BIODIESEL BY INDUCTIVELY COUPLED PLASMA OPTICAL EMISSION SPECTROMETRY (ICP OES)

VITOR CORNAQUI PEREIRA MARROCOS 09 September 2024 (has links)
[pt] A introdução de solventes orgânicos em espectrômetros com plasma indutivamente acoplado (ICP) representa uma limitação à confiabilidade dos resultados pela incidência de efeitos de matriz. Estratégias de calibração como Standard Dilution Analysis (SDA) e Multi-energy Calibration (MEC) propõem contornar as interferências de matriz, reduzindo o tempo de análise, o consumo de reagentes e a geração de resíduos. Na SDA com dois padrões internos (IS), a aquisição do sinal é feita ao longo do tempo durante a mistura de duas soluções analíticas: uma formada por 50 % de amostra + 50 por cento de solução-padrão contendo os analitos e um IS (S1) e outra formada por 50 por cento de amostra + 50 por cento do branco e um segundo IS (S2). Já na calibração por MEC, que também utiliza duas soluções similares à SDA, porém, sem IS, mede-se simultaneamente sinais dos elementos em diferentes comprimentos de onda. Estes métodos foram aplicados para a determinação de Ca, K, Mg, Na, P, Si e S em amostras de biodiesel diluídas em xileno, por espectrometria de emissão óptica com plasma indutivamente acoplado (ICP OES) e comparados com as calibrações por adição de analito (SA) e padronização interna (IS). Os limites de quantificação não apresentaram diferença significativa em relação aos métodos tradicionais, variando de 0,05 mg kg-1 (Ca) a 1,4 mg kg-1 (Na) para SDA e de 0,01 mg kg-1 (Mg) a 0,98 mg kg-1 (P) para MEC. A veracidade foi verificada através de testes de recuperação em amostras de biodiesel e no material padrão de referência NIST 1084a (Wear metals in lubricating oil), com recuperações de 101 ± 6 por cento para SDA e de 108 ± 8 por cento para MEC. A estabilidade do sinal analítico a longo prazo e os menores impactos econômicos e ambientais fazem a SDA e a MEC interessantes para a determinação elementar em amostras de biodiesel e óleo diluídas em xileno. / [en] Direct introduction of organic solvents into inductively coupled plasma (ICP) spectrometers represents a limitation to reliability of the results due to matrix effects. Different calibration methods, such as Standard Dilution Analysis (SDA) and Multi-energy Calibration (MEC) have been proposed to overcome this kind of interference, reducing analysis time, reagent consumption and waste generation. In SDA with two internal standards (IS), the signal is acquired over time during the mixing process of two analytical solutions: one consisting of 50 percent of sample + 50 percent of analytical standards and IS1 (S1) and the other consisting of 50 percent of sample + 50 percent of blank solution and IS2 (S2). In MEC calibration, which also uses two solutions similarly to SDA, but without IS, signals from the elements are measured simultaneously at different wavelengths. These methods were applied to the determination of Ca, K, Mg, Na, P, Si and S in biodiesel samples diluted in xylene by inductively coupled plasma optical emission spectrometry (ICP OES) and compared to calibrations by standard addition (SA) and internal standardization (IS). Limits of quantification showed no statistically significant difference compared to the traditional methods, whereas the limits found by SDA ranged from 0.05 mg kg-1 (Ca) to 1.4 mg kg-1 (Na) for SDA, and from 0.01 mg kg-1 (Mg) to 0.98 mg kg-1 (P) for MEC. The trueness was verified through recovery tests on biodiesel samples and the standard reference material NIST 1084a (Wear metals in lubricating oil), with recoveries of 101 ± 6 percent for SDA and 108 ± 8 percent for MEC. Long-term signal stability and lower economic and environmental impacts places SDA and MEC as an interesting strategy for elemental determination in biodiesel and oil samples diluted in xylene.
5

Making it happen : prevention of mother to child transmission of HIV in rural Malawi

Kasenga, Fyson January 2009 (has links)
The devastating consequences of HIV/AIDS have caused untold harm and human suffering globally. Over 33 million people worldwide are estimated to be living with HIV and AIDS and a majority of these are in sub-Saharan Africa. Women and children are more infected particularly in sub-Saharan countries. Globally, an estimated number of 370 000 children were newly infected in 2007, mainly through mother to child transmission (MTCT). Implementation of prevention of mother to child transmission (PMTCT) programmes has been introduced in many sub-Saharan countries during the last years. Operational research was conducted to study the demand and adherence of key components within a PMTCT Programme among women in rural Malawi. This study was carried out at Malamulo SDA Hospital in rural Malawi and employed a mixture of both quantitative and qualitative approaches. Data sources included antenatal care (ANC), PMTCT and delivery registers, structured questionnaires, in-depth interviews with HIV positive women in the programme and focus group discussions with community members, health care workers and traditional birth attendants. Over the three year period of the study (January 2005 to December 2007), three interventions were introduced in the antenatal care (ANC) at the hospital at different times. These were HIV testing integrated in the ANC clinic in March 2005, opt-out testing in January 2006 and free maternal services in October 2006. A steady increase of the service uptake as interventions were being introduced was observed over time. HIV testing was generally accepted by the community and women within the programme. However, positive HIV tests among pregnant women were also experienced to cause conflicts and fear within the family. Although hospital deliveries were recognised to be safe and clean, home deliveries were common. Lack of transport, spouse support and negative attitudes among staff were some of the underlying factors. Further study on the quality of care offered in the presence of increased service uptake is required. Community sensitisation on free maternal care and male involvement should be strengthened to enable full utilisation of services. Additionally, service providers at facility and community levels, policy makers at all levels and the communities should see themselves as co-workers in development to reduce preventable maternal and infant mortality including MTCT of HIV.
6

High-silica zeolite nucleation from clear solutions

Cheng, Chil-Hung 12 April 2006 (has links)
Understanding the mechanism of zeolite nucleation and crystallization will enable the zeolite science community to tune zeolite properties during synthesis in order to accommodate the purposes of various applications. Thus there has been considerable research effort in "deciphering" the mechanism by studying the growth course of tetrapropylammonium (TPA)-mediated silicalite-1 using several techniques, such as dynamic light scattering (DLS), small-angle X-ray/neutron scattering (SAXS/SANS), and nuclear magnetic resonance (NMR). While these studies have generated a more comprehensive picture on the silicalite-1 growth mechanism, the general application of the mechanism and how it could be applied to other zeolite systems have not been addressed. This work initially tried to apply the insights developed from the TPAsilicalite- 1 clear solution synthesis by investigating the nanoparticles formation and zeolite growth in several tetraethyl orthosilicate (TEOS)-organocation-water solutions heated at 368 K using SAXS. The results are in contrast to TEOS-TPAOH-water mixtures that rapidly form silicalite-1 at 368 K. These results imply that the developed TPA-silicalite-1 nucleation and crystallization mechanism is not universally applicable to other zeolite systems and TPA-silicalite-1 itself could be a special case. With this in mind, the next goal of this work uses in situ SAXS to revisit silicalite-1 growth kinetics prepared by using several TPA-mimic organocations and some asymmetric geometry organocations. The results clearly show the TPA cation is an extraordinarily efficient structure-directing agent (SDA) due to its moderate hydrophobicity and perfect symmetric geometry. Any perturbation of the hydrophobicity and symmetry of SDA leads to a deterioration of zeolite growth. This work further investigates the influences of alcohol identity and content on silicalite-1 growth from clear solutions at 368 K using in situ SAXS. Several tetraalkyl orthosilicates (Si(OR)4, R = Me, Pr, and Bu) are used as the alternative silica sources to TEOS in synthesizing silicalite-1. Increasing the alcohol identity hydrophobicity or lowering the alcohol content enhances silicalite-1 growth kinetics. This implies that the alcohol identity and content do affect the strength of 1) hydrophobic hydration of the SDA and 2) the water-alcohol interaction, through changing the efficiency of the interchanges between clathrated water molecules and solvated silicate species.
7

Morgondagens Nätverksadministratör

Lööf, Mattias January 2018 (has links)
Datornätverken håller på att förändras i grunden där det traditionella sättet med enheter som konfigureras en och en byts mot ett mer automatiserat sätt. Denna nya typ av nätverk benämns ofta ”Software Defined Network (SDN)” och använder sig av en centraliserad Controller som styr nätverket. För automatisering och användning av applikationer inom SDN används Application Programming Interface(API).Denna nya typ av nätverk förändrar kraven som ställs på nätverksadministratörer och skapar nya möjligheter. Några av dessa möjligheter skapas genom öppnande av API:er där applikationer nu kan integreras in i nätverket. Detta gör att nätverksadministratörer även behöver ha kunskap kring API:er och förstå vilka möjligheter de skapar i nätverket. Rapportens syfte var att redogöra för dessa genom följande frågeställningar: 1. Vilken kompetens kommer att krävas av morgondagens nätverksadministratör (två- till fyra-års sikt) 2. Hur kommer det programmerbara (API) nätverket att förändra sättet att etablera nya tjänster/applikationer i företagens nätverk? 3. Hur kan dessa applikationer implementeras på ett nytt och automatiserat sätt? För att besvara frågeställningarna användes en exempelteknik ”Cisco Software Defined Access (SDA)” som är en ny SDN-lösning släppt på marknaden under 2017.Resultatet från frågeställning ett visade att kunskap kring nya protokoll som implementeras för att lösa utmaningen kring segmentering, mobilitet och säkerhet i nätverk blir viktigt. Exempel på detta var protokollen LISP och VXLAN som tillsammans med ett overlay-lager skapar dessa möjligheter. Resultatet visade även att kunskap kring hur Northbound och Southbound Interfaces används för styrande av nätverksenheterna och integration mellan applikationer blir en viktig kompetens.Resultatet för frågeställning två visade hur API:er förenklar utvecklingen av tredjeparts applikationer, något som gör att användningen och utvecklingen av applikationer kommer öka i allt snabbare takt. Slutligen visade resultatet exempel på hur en brandväggsapplikation kan förenkla och effektivisera arbetet för en nätverksadministratör.
8

Daylight in Schools, An Assesement of Daylight in Juan O’Gorman’s Schools in Mexico City

Pérez Villaseñor, Sergio January 2022 (has links)
Mexico has invested many resources in education ever since the enactment of the 1917 Constitution, where the government committed to providing quality education to every Mexican. Investment has increased over time (INEGI, 1994), but the results have not shown the level of commitment, since Mexico is ranked 32nd out of 34 members in the 2021 OECD Education indicators report (OECD, 2021) as well as falling behind in education level and quality (CONEVAL, 2022). This study focuses on the schools by Juan O’Gorman in 1932 and the Daylight conditions. Considering his methodology and theory adapted to the historical context around him, and the uses required for the building type. This thesis centers on two typical classrooms used in the schools built by Juan O’Gorman. The main goal of this thesis is to answer the question, Do the classrooms following the Functional Modular System by Juan O’Gorman perform as an efficient place to provide education? Does it fulfill the “basic daylight needs” of a primary school? How do the schools use the Functional Modular System performance in today’s context using current international lighting standards? The analysis of the 1933 schools by O’Gorman, showed that there is a need to adjust the codes to match the geographic location of Mexico. Since the results obtained showed that the minimum required levels in sDA, UDI and ASE are met with minimum effort, but the higher thresholds are exceeded. Special attention to glare and direct Sunlight is required to prevent the negative effects of daylight in work and study spaces such as eyestrain, and veiling reflections caused by reading surfaces (Dubois et al., 2019). Further studies are required to analyze the perception of the space, and the academic performance of the users to find the possible consequences of the high glare and contrast levels found in this thesis.
9

Food For Thought: The Effects Of Feeding On Neurogenesis In The Ball Python, Python Regius

Bow, Hannah F 01 June 2023 (has links) (PDF)
Pythons are a well-studied model of postprandial physiological plasticity. Consuming a meal has been shown by past work to evoke a suite of physiological changes in pythons and elicit one of the largest documented increases in post-feeding metabolic rates relative to resting values. However, little is known about how this plasticity manifests in the brains of ball pythons, Python regius. Previous work using the cell-birth marker 5-bromo-12’-deoxyuridine (BrdU) has shown that cell proliferation in the python brain increases six days following meal consumption. This study aimed to confirm these findings and build on them in the long term by tracking the survival and maturation of these newly created cells across a two-month period. We investigated whether these cells differentiated into neurons using double-immunofluorescence for BrdU and a reptile-specific neuronal marker (Fox3). We did not find significantly greater rates of cell proliferation in snakes six days after feeding, but we did observe more newly created cells in neurogenic regions in fed snakes two months after the meal. Feeding did not influence neurogenesis, but feeding does appear to have a neuroprotective effect. More newly created cells survived in fed snakes two months later, particularly in the olfactory bulbs and lateral cortex. These findings shed light on the extent of postprandial plasticity and regional differences in the creation of new neural cells in the brains of ball pythons.
10

Receiver architectures for MIMO wireless communication systems based on V-BLAST and sphere decoding algorithms

Tade, Foluwaso Olunkunle January 2011 (has links)
Modern day technology aspires to always progress. This progression leads to a lot of research in any significant area of improvement. There is a growing amount of end-users in the wireless spectrum which has led to a need for improved bandwidth usage and BER values. In other words, new technologies which would increase the capacity of wireless systems are proving to be a crucial point of research in these modern times. Different combinations of multiuser receivers are evaluated to determine performance under normal working conditions by comparing their BER performance charts. Multiple input, multiple output (MIMO) systems are incorporated into the system to utilise the increased capacity rates achievable using the MIMO configuration. The effect of MIMO on the technologies associated with modern day technological standards such as CDMA and OFDM have been investigated due to the significant capacity potentials these technologies normally exhibit in a single antenna scenario. An in-depth comparison is established before comparison is made with a conventional maximum likelihood (ML) detector. The complexity of the ML detector makes its realization evaluated in such a manner to achieve the same or near ML solution but with lower computational complexity. This was achieved using a proposed modification of the Schnorr-Euchner Sphere decoding algorithm (SE-SDA). The proposed sphere decoder (P-SD) adopts a modification of the radius utilised in the SE-SDA to obtain a near ML solution at a much lower complexity compared to the conventional ML decoder. The P-SD was configured to work in different MIMO antenna configurations. The need for the highest possible data rates from the available limited spectrum led to my research into the multi-user detection scenario and MIMO.

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