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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.
151

Síntese do subsistema de hardware para comunicação de dados com Gigabit Ethernet para o espectrômetro digital do CIERMag / Hardware subsystem synthesis for data communication with Gigabit Ethernet for the digital spectrometer of CIERMag

Rodrigo Rafael Melaré Corrêa 17 February 2014 (has links)
Neste trabalho, é apresentado o desenvolvimento de um IP de rede Ethernet com interface para o barramento Avalon para utilização em conjunto com o processador Nios II da Altera. O IPC foi adaptado do projeto Ethernet_tri_mode, e é capaz de transferir dados a velocidades de 1000, 100 e 10 Mbps. O desenvolvimento envolveu a adaptação do código para atingir os requisitos do projeto, feito segundo as diretrizes do CIERMag de manter todo o código em VHDL. Além disso, foi implementada uma interface de comunicação com o processador Nios II para tornar possível a configuração do sistema, bem como a transferência de dados através de um software sendo executado no processador. O IPC Ethernet foi projetado para ser aplicado no espectrômetro digital em desenvolvimento pelo CIERMag e teve como compromissos a baixa utilização de recursos lógicos do FPGA e, ao mesmo tempo, a disponibilização de uma alta taxa de transferência de dados para o espectrômetro. Como ferramenta de desenvolvimento, foi utilizada a plataforma Quartus II cujo fornecedor é a Altera. Já os testes em placa foram realizados em um kit de desenvolvimento DE3-150 da Terasic, o qual utiliza uma FPGA Stratix III, também da Altera. Com o intuito de testar e validar o sistema, foi desenvolvido um software para o processador Nios II capaz de receber e enviar dados através do IPC e com inteligência para responder pedidos do tipo ARP e PING. O subsistema de Gigabit Ethernet desenvolvido aqui já incorpora a versão corrente do Espectrômetro Digital de RM do CIERMag. / In this work we expose the implementation of an Ethernet network core which interfaces to Avalon bus used along with the Nios II Altera processor. This core was adapted from the Ethernet_tri_mode project. It can transfer data at rates of 1000, 100 and 10 Mbps. The development involved the adaptation of the code to fullfil the project requirements, under the policy of the CIERMag to keep the whole coding in VHDL. Furthermore was implemented an interface to communicate with the Nios II processor to enable system configuration and data transfer through a software running on the processor. The core was projected to be applied with focus on the utilization of low FPGA logical resources with the availability of a high data transfer rate. It will be used in a digital spectrometer under development at the CIERMag. The Quartus II platform, supplied by Altera was used as the development tool. The tests on board where carried out on a DE3-150 development kit from Terasic, which has an FPGA Stratix III also from Altera. In order to test and validate the system, a software for the Nios II processor was developed, able to send and receive data via IPC and with intelligence to answer ARP and PING types requests. The developed Gigabit Ethernet subsystem is now part of the running version of the CIERMag Digital MR Spectrometer.
152

Automação de um espectrômetro por ressonância magnética nuclear pulsada / Automation of a pulsed nuclear magnetic resonance spectrometer

Marco Aurelio de Oliveira Pagnano 27 May 1993 (has links)
Este trabalho consistiu na automação do espectrômetro de Ressonância Magnética Nuclear Pulsada existente no laboratório dos professores José Pedro Donoso e Claudio José Magon. Foram efetuados circuitos adicionais e melhorias no equipamento que eles possuíam, à nível de hardware e software. Foram construídas e programadas interfaces paralelas que ligam o microcomputador a um gerador de pulsos, fabricado pela Tecmag Inc., e a um digitalizador rápido (10 ns) Nicolet 430. O programador de pulsos pode acionar independentemente 75 linhas durante o intervalo de tempo subdividido em 2048 eventos, também independente. O software desenvolvido permite a programação de todas as linhas e eventos de forma eficiente e prática. Foi todo escrito em linguagem C, é modular, portátil, e permite a geração de seqüências de pulsos sofisticadas e também o controle da aquisição e transferência de dados / This work describes the Project developped to automatize the pulsed nuclear magnetic resonance spectrometer housed in the laboratory of the professors José Pedro Donoso e Cláudio José Magon. To satisfy our needs we have improved their old equipment, at the level of hardware and software. Were built and programmed the parallel interface between the microcomputer and a pulse programmer made by Tecmag Inc. and with a fast digitizer (10 ns) Nicolet 430. The pulse programmer can control 75 independent output channels during 2048 time intervals. The software we developped allow us to control the whole pulse sequence on a very efficient and practical way. It was written in C-language, and provides the timing signals necessary to generate sofisticated pulse seqüencies, the data acquisition and data transfer to the host computer
153

Development of the LunaH-Map miniature neutron spectrometer

Vogel, Samuel, Frank, Rebecca, Stoddard, Graham, Christian, James F., Johnson, Erik B., Hardgrove, Craig, Starr, Richard, West, Stephen 24 August 2017 (has links)
There is strong evidence that water-ice is relatively abundant within permanently shadowed lunar surface materials, particularly at the poles. Evidence for water-ice has been observed within the impact plume of the LCROSS mission and is supported by data gathered from the Lunar Exploration Neutron Detector (LEND) and the Lunar Prospector Neutron Spectrometer (LPNS). Albedo neutrons from the Moon are used for detection of hydrogen, where the epi-thermal neutron flux decreases as hydrogen content increases. The origin on the concentration of water within permanently shadowed regions is not completely understood, and the Lunar Polar Hydrogen Mapper (LunaH-Map) mission is designed to provide a high-resolution spatial distribution of the hydrogen content over the southern pole using a highly elliptical, low perilune orbit. The LunaH-Map spacecraft is a 6U cubesat consisting of the Miniature Neutron Spectrometer (Mini-NS). Mini-NS is not collimated, requiring a low altitude to achieve a higher spatial resolution compared to previous missions. To develop a compact neutron detector for epi-thermal neutrons, the Mini-NS comprises of 2-cm thick slabs of CLYC (Cs2LiYCl6), which provide a sensitivity similar to a 10-atm, 5.7-cm diameter He-3 tubes, as used in LPNS. The Mini-NS digital processing electronics can discriminate by shape and height to determine signal (albedo neutrons) from background (cosmic rays). The Mini-NS achieves a total active sensing area of 200 cm(2) and is covered with a cadmium sheet to shield against thermal neutrons. The research and development on the detector modules show a robust design ready for space flight.
154

Monte Carlo simulation and aspects of the magnetostatic design of the TRIUMF second arm spectrometer

Duncan, Fraser Andrew January 1988 (has links)
The optical design of the TRIUMF Second Arm Spectrometer (SASP) has been completed and the engineering design started. The effects of the dipole shape and field clamps on the aperture fringe fields were studied. It was determined that a field clamp would be necessary to achieve the field specifications over the desired range of dipole excitations. A specification of the dipole pole edges and field clamps for the SASP is made. A Monte Carlo simulator for the SASP was written. During the design this was used to study the profiles of rays passing through the SASP. These profiles were used in determining the positioning of the dipole vacuum boxes and the SASP detector arrays. The simulator is intended to assess experimental arrangements of the SASP. / Science, Faculty of / Physics and Astronomy, Department of / Graduate
155

Automated Low-cost Instrument for Measuring Total Column Ozone

Nebgen, Gilbert Bernard 05 1900 (has links)
Networks of ground-based and satellite borne instruments to measure ultraviolet (UV) sunlight and total column ozone have greatly contributed to an understanding of increased amounts of UV reaching the surface of the Earth caused by stratospheric ozone depletion. Increased UV radiation has important potential effects on human health, and agricultural and ecological systems. Observations from these networks make it possible to monitor total ozone decreases and to predict ozone recovery trends due to global efforts to curb the use of products releasing chemicals harmful to the ozone layer. Thus, continued and expanded global monitoring of ozone and UV is needed. However, existing automatic stratospheric ozone monitors are complex and expensive instruments. The main objective of this research was the development of a low-cost fully automated total column ozone monitoring instrument which, because of its affordability, will increase the number of instruments available for ground-based observations. The new instrument is based on a high-resolution fiber optic spectrometer, coupled with fiber optics that are precisely aimed by a pan and tilt positioning mechanism and with controlling programs written in commonly available software platforms which run on a personal computer. This project makes use of novel low-cost fiber optic spectrometer technology. A cost advantage is gained over available units by placing one end of the fiber outdoors to collect sunlight and convey it indoors, thereby allowing the spectrometer and computer to be placed in a controlled environment. This reduces the cost of weatherproofing and thermal compensation. Cost savings also result from a simplified sun targeting system, because only a small pan and tilt device is required to aim the lightweight fiber optic ends. Precision sun-targeting algorithms, optical filter selection, and software to derive ozone from spectral measurements by the spectrometer are a major contribution of this project. This system is a flexible platform which may be adapted to study other atmospheric constituents such as sulfur dioxide, nitrous oxides, and haze.
156

Návrh kompaktního spektrometru s transmisní mřížkou a posuvným spektrálním rozsahem / Design of compact spectrograph with shiftable spectral range based on transmission gratings

Malina, Jan January 2020 (has links)
The aim of this diploma thesis is to design a compact spectrometer with a transmission grating and a shiftable spectral range for the method of laser-induced breakdown spectroscopy (LIBS). The work in the theoretical part contains a basic description of spectroscopy and spectroscopic methods of LIBS, spectrometer and its individual parts. The practical part describes the spectrometer design procedure, introduces selected components and comments on the reason for their selection. Selected components are assembled into the final form of a spectrometer, which is further tested with the help of a simulation program to confirm its functionality. The result of the work is a comprehensive overview of the individual components of the spectrometer, aspects of its construction together with instructions and advice on its assembly, along with an example in the form of a designed set of commonly available catalog components.
157

Investigation of the enhancement of the performance of the SIMS instruments / Recherche sur l'amélioration de la performance des instruments SIMS

Verruno, Marina 06 November 2017 (has links)
Résumé : Les instruments de spectrométrie de masse à ionisation secondaire (SIMS) doivent être améliorés afin de satisfaire les exigences et tendances dans de nombreux domaines qui demandent des outils d'analyse pouvant cartographier les échantillons à la fois avec une excellente résolution et une haute sensibilité chimique, mais également avec des temps d’analyse plus court. Les objectifs de cette thèse sont : rechercher à améliorer la résolution en masse des spectromètres de masse à double focalisation en remplaçant le secteur sphérique standard par une nouvelle géométrie sphéroïde ayant de meilleures propriétés de focalisation, et d’étudier la réduction du temps d'analyse en imagerie SIMS, par la preuve de concept du système SIMS à multifaisceaux d'ions. Une comparaison des principales propriétés de focalisation du secteur sphérique, de la géométrie sphéroïde et d’une géométrie de sphéroïde hybride, a été réalisée en utilisant le logiciel SIMION. Une comparaison dans une configuration Nier-Johnson entre le secteur sphérique et le sphéroïde, a montré que le faisceau présente une rotation de 90 ° à la sortie de l'aimant nuisant à la résolution de masse dans la configuration sphéroïde. En ajoutant un élément électrostatique pouvant tourner le faisceau à 90 ° les performances du spectromètre de masse pourrait être amélioré. Toutefois, une comparaison des performances entre les secteurs sphériques et hybrides dans une configuration Mattauch-Herzog a montré que lorsque la double condition de focalisation est optimisée, une meilleure résolution de masse pourrait être obtenue avec la géométrie sphéroïde. Un système multi-faisceau ionique a été étudié pour l'analyse SIMS. La simulation à travers l’optique secondaire d'un Cameca IMS XF de neuf faisceaux a montré une transmission réussie des faisceaux, résultant en neuf points concentrés sur le détecteur plaque à canaux multiples (MCP). La preuve de concept a été achevée expérimentalement dans l'IMS 6F de Cameca, où une ouverture à trous multiples était montée dans la colonne principale, générant 9 et 16 faisceaux de tailles comprises entre 4 µm à 10 µm. Des images d'une grille AlCu ont été obtenues en balayant l'échantillon par le système de multifaisceaux d’ions. Ces résultats montrent que le système multi-faisceau d'ions est une technique possible pour l'imagerie SIMS et qu'en optimisant leur conception les multi-nano-faisceaux d'ions seront une solution permettant de réduire considérablement le temps d'analyse. / Secondary ion mass spectrometry (SIMS) instruments need to be improved in order to satisfy the demands of trends in many fields that require analytical tools that can map samples with both excellent resolution and high-sensitivity chemical information, but also with shorter time of analysis. The objectives of this thesis are: investigate the enhancement of the mass resolution of double focusing mass spectrometers by replacing the standard spherical sector with a novel spheroid geometry which has better focusing properties, and to investigate the reduction of the time of analysis in imaging SIMS by the proof-of-concept of the SIMS multi-ion- beam system.A comparison of the main focusing properties of the spherical sector, the spheroid geometry and a hybrid spheroid geometry, was made using the SIMION software. A comparison in a Nier-Johnson configuration between the spherical sector and the spheroid, showed that the beam presents a rotation of 90° at the exit of the magnet harming the mass resolution in the spheroid configuration. By adding an electrostatic element that can rotate the beam 90° the performance of the mass spectrometer could be improved. However, a comparison of the performances between the spherical and hybrid sectors simulated in a Mattauch-Herzog configuration, showed that when the double focusing condition is properly satisfied, better mass resolution could be achieved with the spheroid geometry.A multi-ion-beam system was investigated for SIMS analysis. A simulation through the secondary optics of a Cameca IMS XF showed successful transmission of nine beams through the optics resulting in nine well focussed spots on the multi channel plate (MCP) detector. The proof-of-concept was completed experimentally in the Cameca IMS 6F, where a multi-hole aperture was mounted in the primary column generating 9 and 16 beams of sizes between 4 μm to 10 μm. Images of an AlCu grid were obtained when t the multi-ion-beam system was scanned over the sample. These results showed that the multi-ion-beam system is a feasible technique for imaging SIMS and by optimizing the design multi-nano-ion-beams will be a solution for reducing drastically the time of analysis.
158

Measuring sub-femtosecond temporal structures in multi-ten kiloampere electron beams

Zarini, Omid 29 May 2019 (has links)
In laser wakefield acceleration, an ultra-short high-intensity laser pulse excites a plasma wave, which can sustain accelerating electric fields of several hundred GV/m. This scheme advances a novel concept for compact and less expensive electron accelerators, which can be hosted in a typical university size laboratory. Furthermore, laser wakefield accelerators (LWFA) feature unique electron bunch characteristics, namely micrometer size with duration ranging from several fs to tens of fs. Precise knowledge of the longitudinal profile of such ultra-short electron bunches is essential for the design of future table-top X-ray light-sources and remains a big challenge due to the resolution limit of existing diagnostic techniques. Spectral measurement of broadband coherent and incoherent transition radiation (TR) produced when electron bunches passing through a metal foil is a promising way to analyze longitudinal characteristics of these bunches. Due to the limited reproducibility of the electron source this measurement highly requires single-shot capability. An ultra-broadband spectrometer combines the TR spectrum in UV/NIR (200-1000 nm), NIR (0.9-1.7 µm) and mid-IR (1.6-12 µm). A high spectral sensitivity, dynamic bandwidth and spectral resolution are realized by three optimized dispersion and detection systems integrated into a single-shot spectrometer. A complete characterization and calibration of the spectrometer have been done concerning wavelengths, relative spectral sensitivities, and absolute photometric sensitivities, also taking into account for the light polarization. The TR spectrometer is able to characterize electron bunches with charges as low as 1pC and can resolve time-scales of 0.4 fs. Electron bunches up to 16 fs (rms width) can be reconstructed from their TR spectrum. In the presented work, the self-truncated ionization induced injection (STII) scheme has been explored to study the relevant beam parameters especially its longitudinal bunch profile and the resulting peak current.
159

Electro Optical Circuit Architecture for Photonic Signal Processing

Jahid, Abu 24 June 2022 (has links)
Microwave photonic applications in the terahertz (THz) region of the spectrum are attracting increasing attention due to the need to find solutions for next-generation (5G/6G) wireless communication systems capable of handling unprecedented data rates. It is crucial to develop millimeter-wave (mm-wave) (30-300GHz) fiber supported transport networks. One of the key questions is, which carrier frequency generation technique will be the most suitable for THz signals above 300 GHz; electronics-based or photonics-based. Since the backbone of the wireless networks is composed by very high-capacity fibre optic cables, the microwave photonic approach has the ultimate advantage of seamless integration with existing optical fibre networks. Although the cost effectiveness is still an open question, simplistic base station architecture with simplified antenna units and high optical component reuse is necessary for enabling a compatible mobile network backhaul. For THz applications a broadband electro-optic modulator (EOM) with a frequency response extending to the sub-terahertz range, high power handling, and very low nonlinear distortions, is required. The objective of this thesis is to study the feasibility of photonic integration and, proof of concept implementations with the effective use of optical components with reduced energy consumption, reduced footprint and offer speed beyond all-electronic implementations. The first study presents a coherent electro-optic photonic integrated circuit deploying generalized Mach-Zehnder interferometer (GMZI) substituting N×1 combiner by an optical N×N discrete Fourier transform (DFT) in order to generate a regularly spaced frequency comb. The proposed design comprises of 1×N splitter that feeds light into a parallel array of N electro-optic phase modulators electrically driven by RF signal with a progressive phase shift with their phase modulated optical outputs processed by an N×N optical DFT. A pragmatic design approach and analytical formulation for implementing MMI based optical DFT in photonic networks composed of waveguide splitters, combiners, and phase-shift elements with necessary circuit diagram for even and odd dimensions are presented. Recently, there has been impressive progress toward ultra-wide band low voltage EOM. The heterogeneous approach of utilizing silicon nitride on lithium niobate waveguide integrated on a single chip is demonstrated for the best optical modulation performance that opens a wide range of opportunities for universal linear optical networks, chip-scale MWP systems, ultra-speed switching of optical communications. Finally, the third study de-scribes the architecture for compact on-chip spectrometry targeting high resolution across the entire C-band to measure the spectral profile of WDM signals reliably and accurately in fixed and flex-grid architectures. The design architecture of technologically viable com-pact on-chip high-resolution wideband spectrometer such as Mach-Zehnder delay interferometers (MZDI), 2×2 directional couplers and multimode interference couplers is presented and verified by software simulation using an industry standard tool. The components simulations that supported the assessment of the feasibility of a spectrometer compliant with the specification made use of the LioniX asymmetric double strip (ADS) waveguide and the low-cost photolithography.
160

Design of Miniaturized Time-of-Flight Reflectron Mass Spectrometer for Upper Atmosphere Density Measurements

Pyle, Michelle Lynn 01 May 2016 (has links)
Variations of gas and plasma density and composition in Earth’s thermosphere and ionosphere are key indicators of interactions between different layers of Earth’s atmosphere. The nature of interactions between neutral and ion species in the upper atmosphere is an active area of study in Heliophysics and there is much to learn about the dynamic relationship between the ionosphere and neutral thermosphere. Mass Spectrometers are among an array of instruments used to explore Earth’s upper atmosphere and other space environments. In the past, data from mass spectrometers flown in low earth orbit has been used to improve atmospheric models and to study the dynamics of the ionosphere and thermosphere. Historically, these instruments are substantial in size and deployed on larger satellite platforms. Data from these larger instruments generally provide information from a specific point in time at a single location. Studies of atmospheric density and composition with multiple locations for each time point could be performed by CubeSat swarms if proper instrumentation were available to fit CubeSat payload restrictions. The proposed miniaturized time-of-flight (TOF) mass spectrometer (MS) will have a mass resolution and range sufficient for measuring the composition of Earth’s thermosphere and ionosphere while operating within the power and space constraints of a CubeSat. The capabilities of this instrument could dramatically reduce the cost of future missions while simultaneously enhancing the science return. The design employs miniaturization of TOF-MS technology, including resolution refinement techniques used for larger instruments and standard concepts for TOF-MS components such as acceleration grids, a Bradbury-Nielsen wire gate, a gridless ion mirror, and microchannel plate detector.

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