381 |
Assessing urban air quality through measurements and modelling and its implications for human exposure assessmentWu, Hao January 2017 (has links)
Outdoor air pollution is a major contributor to adverse health effects of citizens, in particular those living in urban environments. Air quality monitoring networks are set up to measure air quality in different environments in compliance with national and European legislation. Generally, only a few fixed monitoring sites are located within a city and thus cannot represent air pollutant concentrations in urban areas accurately enough to allow for a detailed human exposure assessment. Other approaches to derive detailed urban air pollutant concentration estimates exist, such as dispersion models and land-use regression (LUR) models. Low-cost portable air quality monitors are also emerging, which have the potential to add value to existing monitoring networks by providing measurements at greater spatial resolution and also to provide individual-level exposure assessment. The aim of this thesis is to demonstrate how measurements and modelling in combination allow detailed investigations of the variability of air pollutants in space and time in urban area, and in turn improve on the current exposure assessment methods. Three types of low-cost portable monitors measuring NO2, O3 (Aeroqual monitors) and PM2.5 (microPEM monitor) were evaluated against their respective reference instruments. The Aeroqual O3 monitor showed very good correlation (r2 > 0.9) with the respective reference instruments, but biases in the slope and intercept coefficients indicated that calibration of Aeroqual O3 monitor was needed. The Aeroqual NO2 monitor was subject to cross-sensitivity from O3, which, as demonstrated, can be effectively corrected by making O3 and NO2 measurements in tandem. Correlation between the microPEM monitor and its reference instrument was poor (r2 < 0.1) when PM2.5 concentrations were low (< 10 μg m-3), but significantly improved (r2 > 0.69) during periods with elevated PM2.5 concentrations. Relative humidity was not found to affect the raw results of PM2.5 measurements in a consistent manner. All three types of monitors cannot be used as equivalent or indicative methods instead of reference methods in studies that require quantification of absolute pollutant concentrations. However, the generally good correlations with reference instruments reassure their application in studies of relative trends of air pollution. Concentrations of PM2.5, ultrafine particles (UFP) and black carbon (BC) were quantified using portable monitors through a combination of mobile and static measurements in the city of Edinburgh, UK. The spatial variability of UFP and BC was large, of similar magnitude and about 3 times higher than the spatial variability of PM2.5. Elevated concentrations of UFP and BC were observed along streets with high traffic volumes whereas PM2.5 showed less variation between streets and a footpath without road traffic. Both BC and UFP significantly correlated with traffic counts, while no significant correlation between PM2.5 and traffic counts was observed. The relationships between UFP, NO2 and inorganic components of PM2.5 were further investigated through long-term measurements at roadside, urban background and rural sites. UFP moderately correlated with NOx (NO2 + NO) and showed varying relationships with NOx depending on the particle size distribution. Principal component analysis and air-mass back trajectory analysis revealed that PM2.5 concentrations were dominated by long-range transport of secondary inorganic aerosols, whereas UFP were mainly related to varying local emissions and meteorological conditions. These findings imply the need for different policies for managing human exposure to these different particle components: control of much BC and UFP appears to be manageable at local scale by restricting traffic emissions; however, abatement of PM2.5 requires a more strategic approach, in cooperation with other regions and countries on emissions control to curb long-range transport of PM2.5 precursors. A dispersion model (ADMS-Urban) was used to simulate high resolution NO2 and O3 concentrations in Edinburgh. The effects of different emission and meteorological input datasets on the resulting modelled NO2 concentrations were investigated. The modelled NO2 and O3 concentrations using the optimal model setup were validated against reference instrument and diffusion tube measurements. Temporal variability of NO2 was predicted well at locations that were not heavily influenced by local effects, such as road junctions and bus stops. Temporal variability of O3 was predicted better than for NO2. Long-term spatial variability of NO2 was found to correlate well with diffusion tube measurements, while modelled spatial variability of O3 in ADMS-Urban compared poorly with diffusion tube measurements. However, it was found that the O3 diffusion tube measurements may be subject to some unidentified biases affecting their accuracy. Land-use regression (LUR) models are widely used to estimate exposure to air pollution in urban areas. An appropriately sized and designed monitoring network is an important component for the development of a robust LUR model. Concentrations of NO2 were simulated by ADMS-Urban at ‘virtual’ monitoring sites in 54 different network designs of varying numbers and types of site, using a 25 km2 area including much of the Edinburgh city area. Separate LUR models were developed for each network. These LUR models were then used to estimate ambient NO2 concentrations at all residential addresses, which were evaluated against the ADMS-Urban modelled concentration at these addresses. The improvement in predictive capability of the LUR models was insignificant above ~30 monitoring sites, although more sites tended to yield more precise LUR models. Monitoring networks containing sites located within highly populated areas better estimated NO2 concentrations across all residential locations. LUR models constructed from networks containing more roadside sites better characterised the high end of residential NO2 concentrations but had increased errors when considering the whole range of concentrations. No particular composition of monitoring network resulted in good estimation simultaneously across all residential NO2 concentration and of the highest NO2 levels implying a lack of spatial contrast in LUR-modelled pollution surface compared with the dispersion model. Finally, the results from the measurement and modelling studies presented in thesis are synthesised in the context of current exposure assessment studies. Low-cost air-quality monitors currently do not possess and are unlikely in the near future to provide the robustness and accuracy to replace the existing routine monitoring network. Development of the low-cost air-quality should be aiming at upgrading them as the indicative method as defined in the data quality objective in the EU directive. The monitoring sites used to build LUR models should capture well the population distribution in the study area as opposed to capturing the greatest pollution contrast. The traditional methods of evaluating LUR models are also ineffective in characterising the models’ capability at estimating pollutant concentration at residential address. Given that the dispersion models are also subject to the availability and uncertainties in the input data, future air quality model development should endeavour to incorporate both dispersion and land-use regression models, where the uncertainty in the input data can be reduced by using LUR models built on actual measurements, and the limitation in the statistical modelling can be replaced by adopting the deterministic approach used in the dispersion model.
|
382 |
A critical analysis of the coverage of Uganda's 2000 referendum by The New Vision and The Monitor newspapersWakabi, Wairagala January 2003 (has links)
On July 29 2000, Uganda held a referendum to decide whether to continue with the ruling Noparty Movement system or to revert to the Multi-party platform. This research entails a qualitative content analysis of the role the media played in driving debate and understanding of the referendum and its role in the country’s democratisation process. The research is informed by Jurgen Habermas’s public sphere paradigm as well as the sociological theory of news production. The research covers Uganda’s two English dailies – The New Vision and The Monitor, examining whether they provided a public sphere accessible to all citizens and devoid of ideological hegemony. It concludes that the newspapers were incapable of providing such a sphere because of the structural nature of Ugandan society and the papers’ own capitalistic backgrounds and ownership interests. The research concludes that such English language newspapers published in a country with a low literacy rate and low income levels, can only provide a public sphere to elite and privileged sections of society. A case is then made that multiple public spheres would be better suited to represent the views of diverse interest groups.
|
383 |
Efeitos de uma intervenção com monitores de Organização Não-Governamental para minimizar problemas de comportamento em criançasCosta, Carolina Severino Lopes da 23 February 2010 (has links)
Made available in DSpace on 2016-06-02T19:44:06Z (GMT). No. of bitstreams: 1
2993.pdf: 2011345 bytes, checksum: f77b5072d3f4355c6fd100c83c98c439 (MD5)
Previous issue date: 2010-02-23 / Financiadora de Estudos e Projetos / Considerando que os problemas de comportamento trazem conseqüências indesejáveis para os indivíduos que os apresentam e para os diferentes contextos em que vivem, o presente estudo teve por objetivo geral avaliar os efeitos de uma intervenção com monitores de uma Organização Não-Governamental (ONG), direcionada ao atendimento de crianças de risco, para minimizar problemas de comportamento das mesmas. Participaram do estudo seis monitores, 24 crianças com idades variando entre oito e onze anos, e pelo menos um de seus responsáveis. O estudo foi realizado nas dependências físicas de uma ONG, situada em uma cidade de médio porte do estado de São Paulo. Para avaliação dos problemas de comportamento infantis foram utilizados os seguintes instrumentos: a) Questionário de Capacidades e Dificuldades (SDQ), respondido por pais e monitores; b) Social Skills Rating Sistem BR (SSRS), versão para professores; e c) Protocolo de observação dos problemas de comportamento infantil (POPCI). Para identificação do repertório de práticas educativas dos monitores foram utilizados: a) Questionário das Relações Interpessoais (QRI); b) Protocolo de Observação dos Comportamentos do Monitor em Relação à Classe (POCMC). Foi utilizado o delineamento Pré-teste e Pós-Teste, tanto com os dados das crianças como com os dos monitores. A intervenção consistiu em duas fases, sendo a primeira denominada de capacitação, objetivando ensinar práticas educativas aos monitores para lidar com problemas de comportamento infantil. A segunda fase, chamada de consultoria, visou aprimorar características dos serviços prestados pela ONG. De modo geral, os resultados mostraram que o presente estudo produziu impactos positivos sobre a diminuição dos índices (quantitativos) dos problemas de comportamento das crianças e maximização dos índices ligados ao repertório de habilidades sociais e comportamento pró-social. Além disso, obteve-se também resultados positivos sobre características da atuação dos monitores com relação às crianças, por meio de aumento na freqüência de categorias comportamentais positivas e diminuição de categorias comportamentais negativas dos monitores. Adicionalmente, foi possível identificar contribuições positivas desse estudo, no sentido de aprimorar algumas características dos serviços prestados pela ONG à sua população-alvo, como reformulação das diretrizes de funcionamento interno e modificação no horário e rotina. Sugere-se que estudos futuros sejam realizados para validar os resultados da presente pesquisa, por exemplo, replicando-o com maior tamanho da amostra e/ou utilizando um delineamento experimental (grupos randomizado). Considera-se, relevante também a realização de estudos de caracterização da população-alvo de ONGs e de suas necessidades, para possibilitar que as mesmas possam adequar os serviços prestados. Tudo leva a crer que a ONG com funcionários capacitados tenha um desempenho importante ao contraturno escolar, diminuindo problemas de populações de risco psicossocial.
|
384 |
An FPGA based 3.8 Tbps Data Sourcing and Emulator System / Um sistema de fonte de dados e emulação de 3.8 Tbps baseado em FPGARamalho, Lucas Arruda 23 February 2018 (has links)
Submitted by LUCAS ARRUDA RAMALHO null (lucasarrudaramalho@gmail.com) on 2018-03-14T22:14:34Z
No. of bitstreams: 1
Ramalho_Tese_2018.pdf: 8417019 bytes, checksum: 0b39588579fa6ac3abad291909bc4662 (MD5) / Approved for entry into archive by Cristina Alexandra de Godoy null (cristina@adm.feis.unesp.br) on 2018-03-15T14:45:53Z (GMT) No. of bitstreams: 1
ramalho_la_dr_ilha.pdf: 8417019 bytes, checksum: 0b39588579fa6ac3abad291909bc4662 (MD5) / Made available in DSpace on 2018-03-15T14:45:53Z (GMT). No. of bitstreams: 1
ramalho_la_dr_ilha.pdf: 8417019 bytes, checksum: 0b39588579fa6ac3abad291909bc4662 (MD5)
Previous issue date: 2018-02-23 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / A evolução dos Multi Gigabit Transceivers (MGT) nos Field Programmable Gate Arrays (FPGA) trouxeram oportunidades para o desenvolvimento de sistemas de aquisição e formatadores de dados em diversas áreas. As novas famílias de FPGAs são capazes de lidar com canais de transmissão com velocidade da ordem de Gbps que utilizam protocolos seriais de alta velocidade, podendo assim se tornar o futuro dos processadores downstream ou upstream. Os sistemas digitais criados para esse propósito, precisam ser confiáveis e síncronos entre dezenas de canais e placas. Como forma de permitir o teste de projetos com essa taxa massiva de bits, essa tese descreve o desenvolvimento do Data Sourcing System (DSS). Esse sistema deve ser capaz de testar qualquer application upstream ou downstream, permitir controle e acesso remoto aos sinais internos dos FPGAs, medir sincronismo e latência entre MGTs e avaliar integridade de links através de bit error rate (BER). Este trabalho faz parte de uma colaboração internacional liderada pelo Fermilab que propôs, com a contribuição do sistema descrito nesta tese, um sistema de trigger de nível 1 para o Compact Muon Solenoid (CMS) Outer Tracker. O dectetor CMS é um experimento vinculado ao European Organization for Nuclear Research (CERN). O DSS foi implementado sobre a placa Pulsar 2b, uma placa padrão Advanced Telecommunication Computing Architecture (ATCA), desenvolvida pelo Fermilab, que conta com um dispositivo FPGA para programação e costumização de aplicações. O setup de hardware utilizado foi construído sobre dois bastidores ATCA com 12 placas Pulsares 2b em cada. A taxa de dados máxima atingida foi de 3.84 Tbps entre os dois bastidores ATCAs. O DSS está operacional e foi utilizado para emular o fluxo de dados de saída do CMS Silicon Outer Tracker, e auxiliar na demonstração da proposta trigger de nível 1. Esta tese descreve essa demonstração como estudo de caso, que testa o formatador de dados do trigger (downstream) através do DSS e- mulando a saída de dados do detector. Nesse estudo de caso, tanto o DSS e o trigger proposto foram implementados utilizando o mesmo hardware ATCA e a Pulsar 2b. O foco do estudo de caso é descrever a comunicação entre o Data Sourcing shelf e o Pattern Recognition shelf. O DSS atendeu aos requisitos da demonstração provendo uma interface de usuário que permite aos desenvolvedores de trigger inserir sinais de controle e executar operações de leitura e escrita de forma remota nos FPGAs. / The evolution of Fiel Programmable Gate Array (FPGA) Multi Gigabit Transceivers (MGT) brought opportunities for data formatter and data acquisition projects in several areas. The newer FPGA families are capable of handling Gigabits per second (Gbps) I/Os implemented using high speed serial link protocols and to become the future downstream processors. The digital systems created for that purpose need to be reliable and synchronous between dozens of channels and boards. To allow the test of such massive bitrate projects, this work implemented the Data Sourcing System (DSS) e- mulator that is able to produce synchronized data in 12 boards, 480 channels, delivering up to 8 Gbps for each of them. This work is part of a international collaboration, led by Fermilab, that proposed with the contribuition of the system described in this thesis, a Level 1 (L1) tri- gger for the Compact Muon Solenoid (CMS) Outer Tracker. The CMS detector is an European Organization for Nuclear Research (CERN) experiment. The DSS is based on the Pulsar 2b, a custom Advanced Telecommunication Computing Architecture (ATCA) standard FPGA-based board designed by Fermilab to be a scalable high speed link processor system. This hardware setup was implemented at Fermilab using two interconnected ATCA shelves with 12 Pulsar 2b on both. The results show that the system is able to provide data at 3.8 Terabits per second (Tbps), and to measure synchronization, latency and bit error rate of the MGTs. The system is operational and was already used to emulate the CMS Silicon Tracker data, and helped the demonstration of a L1 Trigger approach. This thesis describes the demonstration performed as case of study, which used the DSS as upstream system and tested the trigger data delivery as a downstream. In the case of study, both DSS and the proposed trigger are performed by the same ATCA hardware and the Pulsar 2b. The case of study focused to describe the communication between the Data Sourcing shelf and the Pattern Recognition shelf. Data Sourcing reached those requirements for the demonstration and provided a user interface that allows the trigger developers to insert control signals or to perform W/R operations inside Pulsar 2b FPGA block memories.
|
385 |
Avaliação da qualidade dos dispositivos de exibição e salas de laudo em serviços de radiodiagnóstico de hospitais-escola da região nordeste do Brasil / Quality assessment of display devices and rooms report in radiodiagnosis services from hospitals school of northeast region of BrazilAmorim, Ricardo Santos de 21 March 2015 (has links)
In this work we evaluate the quality of display devices - monitors and negatoscopes - radiological medical images, as well as the lighting of the rooms report of a group of seven hospitals - School of Northeastern Brazil, distributed by Northeastern capitals of five states . The data shows serious problems in terms of display and visualization of these hospitals. The valuation of these items reflects directly in providing a correct medical diagnosis. Parameters evaluated in digital displays, proposed by the American Association of Physicists in Medicine were the geometric distortion, reflection, luminance, luminance uniformity, resolution, noise and glare. The negatoscopes were evaluated following the recommendations of Spanish Protocol of Quality Control of the 2002, the American College of Radiology and the Ministry of Health (ANVISA). We investigated the luminance of negatoscopes from general radiology and mammography, which must present acceptable limits of operation as well as the illuminance of rooms report that may interfere with the outcome of the report. We note here that a considerable part of the devices analyzed are at odds with protocololos quality control, thus demonstrating a serious public health problems in the northeast. / Neste trabalho avaliamos a qualidade dos dispositivos de exibição - monitores e negatóscopios - de imagens médicas radiológicas, bem como as condições de iluminação das salas de laudo de um grupo de sete Hospitais - Escola da Região Nordeste do Brasil, distribuídos pelas capitais nordestinas de cinco estados. Os dados demonstram sérios problemas nas condições de exibição e visualização destas instituições hospitalares. A avaliação destes itens reflete diretamente no fornecimento de um diagnóstico médico correto. Os parâmetros avaliados nos monitores digitais, propostos pela Associação Americana de Físicos em Medicina foram os de distorção geométrica, reflexão, luminância, uniformidade de luminância, resolução, ruído e velamento. Os negatóscopios e as salas de laudo foram avaliados seguindo as recomendações do Protocolo Espanhol de Controle de Qualidade de 2002, do Colégio Americano de Radiologia e do Ministério da Saúde (ANVISA). Foi investigada a luminância dos negatoscópios de radiologia geral e de mamografia, que devem apresentar limites aceitáveis de funcionamento, bem como a iluminância das salas de laudo que podem interferir no resultado final do laudo. Verificamos neste trabalho que uma parte considerável dos dispositivos analisados estão em desacordo com os protocolos de controle de qualidade, demonstrando assim, um grave problema de saúde pública na região nordeste.
|
386 |
Development of a CMOS pixel sensor for embedded space dosimeter with low weight and minimal power dissipation / Développement d'un capteur à pixels CMOS pour un dosimètre spatial embarqué de faible poids et avec une dissipation de puissance minimaleZhou, Yang 23 September 2014 (has links)
Cette thèse porte sur le développement d'un capteur de pixel monolithique CMOS utilisé pourl’identification et le comptage des particules ionisés dan l’espace avec un flux élevé. Un nouveauconcept pour l’identification de l’espèce des particules proposé dans la présente étude, est basésur l'analyse des amas de particules déclenchés. Pour valider ce nouveau concept, un capteur detaille complet, qui comprend la matrice de pixel sensible aux particules ionisés signal, une chaînede traitement du signal analogique, un convertisseur analogue numérique de 3 bits, et untraitement du signal numérique a été conçu dans un processus de 0.35 μm. Le capteur sortiedirectement des informations de flux à travers 4 canaux avec un débit de données très faible(80 bps) et dissipation d’énergie minimale (~ 100 mW). Chaque canal représente particules avecdifférentes espèces et les énergies. La densité maximum de flux mesurable est jusqu'à 108particules/cm2/s (coups s'accumulent < 5%). Un prototype à échelle réduite a été fabriqué et testéavec trois types d'illumination de rayonnement (rayons X, les électrons et laser infrarouge). Tousles résultats obtenus valident le nouveau concept proposé. Un moniteur de rayonnement spatialtrès miniaturisé basé sur un capteur de pixel CMOS peut être prévu. Le moniteur peut présente lesmêmes performances que les compteurs actuels, mais avec une dissipation de puissance réduited'un ordre de grandeur qu'un poids, un volume d'encombrement et un coût moindre. En outre, enraison de ses sorties de haut niveau et faible débit de données, aucune traitement supplémentairedu signal dehors du capteur est nécessaire, ce qui le rend particulièrement attrayant pour desapplications dan les petits satellitaires. / This thesis focuses on the development of a CMOS monolithic pixel sensor used for space ionizingparticles identification and counting in high flux. A new concept for single particle identification isproposed in this study, which is based on the analysis of particle triggered clusters. To validate thisnew concept, a full size sensor including the sensitive pixel matrix, an analogue signal processingchain, a 3-bit analogue to digital converter, and a digital processing stage was designed in a 0.35μm process. The sensor directly output particles flux information through 4 channels with a verylow data rate (80 bps) and minimal power dissipation (~ 100mW). Each channel representsparticles with different species and energies. The highest measurable flux density is up to 108particles/cm2/s (hits pile up < 5%). A reduced scale prototype was fabricated and tested with 3types of radiation illumination (X-ray, electrons and infrared laser). All the results obtained validatethe proposed new concept and a highly miniaturized space radiation monitor based on a singleCMOS pixel sensor could be foreseen. The monitor could provide measurements of comparable orbetter quality than existing instruments, but at around an order of magnitude lower powerconsumption, mass and volume and a lower unit cost. Moreover, due to its high level and low datarate outputs, no signal treatment power aside the sensor is required which makes it especiallyattractive for small satellite application.
|
387 |
Physical activity in natural environments : importance of environmental quality, landscape type and promotional materialsElliott, Lewis Roland January 2016 (has links)
Physical inactivity and disconnection from natural environments threatens human health. However, research has demonstrated that natural environments potentially support health-enhancing physical activity which could confer greater physical and mental health benefits than physical activity in other types of environment. This thesis approached the study of physical activity in natural environments through three related pieces of research. Firstly, an experimental study was carried out to explore how the presence of litter in beach environments affected psychophysiological responses to exercise. Responses to exercise did not differ in littered and clean conditions but there was evidence that order effects influenced findings. Visual attention to the two scenes differed, but did not mediate differences in psychophysiological responses. Secondly, analysis of a national dataset was undertaken to explore the form and quantity of physical activity conducted within natural environments in England. A series of linear regressions revealed that higher-intensity physical activities occurred in countryside environments, but more total energy expenditure occurred in coastal environments. Thirdly, a quantitative content analysis of brochures which promote recreational walking in natural environments was conducted which investigated their use of persuasive behavioural messages. These brochures omitted behavioural techniques which may be effective at motivating inactive individuals to walk. Extending this, an online survey tested whether improving brochure content heightened intentions to walk in natural environments. By designing content based on the theory of planned behaviour, the intentions of inactive individuals to undertake walking in natural environments were increased. The findings from this thesis demonstrate that the protection of natural environments is vital for preserving and promoting active recreation and could contribute to population-level increases in physical activity with theory-based promotion in the future.
|
388 |
Intense pulsed neutron generation based on the principle of Plasma Immersion Ion Implantation (PI3) techniqueMotloung, Setumo Victor January 2006 (has links)
Magister Scientiae - MSc / The development of a deuterium-deuterium/ tritium-deuterium (D-D/ D-T) pulsed neutron generator based on the principle of the Plasma Immersion Ion Implantation (PI3) technique is presented, in terms of investigating development of a compact system to generate an ultra short burst of mono-energetic neutrons (of order 1010 per second) during a short period of time (< 20μs) at repetition rates up to 1 kHz. The system will facilitate neutron detection techniques, such as neutron back-scattering, neutron radiography and time-of-flight activation analysis. Aspects addressed in developing the system includes (a) characterizing the neutron spectra generated as a function of the target configuration/ design to ensure a sustained intense neutron flux for long periods of time, (b) the system was also characterised as a function of power supply operating conditions such as voltage, current, gas pressure and plasma density. / South Africa
|
389 |
Diagnostics and characterization of beam halo at the KEK Accelerator Test Facility / Mesures et caractérisation du halo du faisceau de l'accélérateur ATF au KEKYang, Renjun 05 October 2018 (has links)
Aux futurs collisionneurs linéaires et circulaires, la présence d’un halo autour du faisceau est susceptible de fortement limiter les performances, et peut également activer, voire endommager, les composants de l’accélérateur. Le halo doit par conséquent est contrôlé par un système de collimateurs efficace. Pour évaluer l’impact sur les expériences de physique des particules ainsi que les efficacités de collimation, une bonne compréhension des mécanismes physiques générateurs de halo est essentielle, pour par exemple prédire les distributions de probabilité de manière fiable. Pour ce faire, une investigation systématique ont été menée à l’Accelerator Test Facility (ATF) du KEK dans le cadre de cette thèse, d’abord à travers une analyse théorique des principales sources de halo dans ATF, puis moyennant le développement et l’implémentation de diagnostiques dédiés aux mesures du halo, dont les résultat sont ensuite présentés et comparés aux prédictions théoriques. Le halo produit par la diffusion des particules du faisceau sur les noyaux des molécules du gaz résiduel dans la chambre à vide (« Beam Gas Scattering » - BGS) est d’abord estimé analytiquement, avec certaines approximations, puis moyennant une simulation Monte-Carlo. Un nombre considérable de particules de halo BGS est prédit, ainsi qu’une dépendance dans la pression de gaz résiduel. Pour étudier la possible formation d’un halo par le mécanisme de diffusion intra-paquet à grand angle dit de « Touschek » en présence d’une dispersion optique résiduelle, le taux de cette diffusion a été estimé en fonction de plusieurs paramètres faisceau pertinents. Une simulation Monte-Carlo de la diffusion intra-faisceau à petit angle (IBS) et de « Touschek » est aussi en cours de développement. Pour tester les prédictions théoriques, les performances d’un détecteur de halo déjà existant basé sur un capteur diamant ont été améliorées moyennant une technique de repondération qui a permis d’en augmenter la gamme dynamique jusqu’à 10⁵. Afin de disposer d’un instrument complémentaire pour mesurer le halo, un moniteur YAG/OTR a aussi été conçu, construit et installé dans la ligne d’extraction d’ATF. Il a pu être montré que la gamme dynamique et la résolution de ce moniteur YAGOTR sont, respectivement, autour de 10⁵ et inférieure à 10 μm. Grâce aux diagnostiques développés pour mesurer le halo du faisceau d’ATF, les distributions transverses et en énergie ont pu être étudiées. L’accord satisfaisant obtenu entre les prédictions théoriques et les mesures, ainsi qu’une dépendance importante dans la pression de gaz résiduel, ont permis de montrer que la distribution verticale du halo est dominée par le mécanisme BGS. Par contre, la distribution horizontale est bien supérieure aux prédictions BGS, et est par ailleurs asymétrique. L’asymétrie observée peut être en partie reliée à la qualité du champ de l’élément pulsé servant à l’extraction du faisceau d’ATF, ainsi qu’à certaines aberrations dans le transport optique. La distribution de probabilité du halo en fonction de l’énergie a par ailleurs pu être mesurée, grâce à une technique nouvelle d’ajustement de la dispersion optique dans le plan vertical, et a été trouvée compatible qualitativement avec le mécanisme de diffusion « Touschek ». Un scénario plausible de génération du halo dans le plan horizontal a ainsi pu être suggéré. / At future linear and circular colliders, beam halo can strongly limit machine performances, cause as well component damage and activation, and should, therefore, be controlled by an efficient collimation system. To evaluate the impact on particle physics experiments and collimation efficiencies, a clear understanding of beam halo formation mechanisms is essential, e.g., to predict halo distribution reliably. For this purpose, systematic investigations have been carried out at the Accelerator Test Facility (ATF) of KEK. In this dissertation, the theoretical analysis of the primary halo sources at ATF and the development of dedicated halo diagnostics are presented. Measurements of beam halo at ATF are also described and compared with the theoretical predictions. Beam halo arising from Beam-Gas Scattering (BGS) in the damping ring was firstly estimated through analytical approximations and a Monte Carlo simulation. A considerable amount of halo particles generated by BGS and the corresponding vacuum dependence have been predicted. To explore the probability of beam halo formation from Touschek scattering in the presence of dispersion, the Touschek scattering rate was estimated with respect to relevant beam parameters. Furthermore, a Monte Carlo simulation of Intra-Beam Scattering (IBS) and Touschek scattering is under development. To probe the theoretical predictions, the performance of an already existing diamond sensor detector was optimized via a data rescaling technique to increase the dynamic range to 1×10⁵. For a complementary diagnostics of beam halo, a YAG/OTR monitor was also designed and installed in the extraction section of ATF2. The dynamic range and resolution of the YAG/OTR monitor have been shown to be around 1×10⁵ and less than 10 μm, respectively. Thanks to the halo monitors developed at ATF2, the transverse halo and momentum tail have been studied. Satisfactory agreement between numerical predictions and measurements as well as a significant vacuum dependence indicate that the BGS process dominates the vertical halo. On the other hand, the horizontal halo appeared to be higher than the prediction from BGS, and moreover asymmetric. The observed asymmetry was shown to be related to the quality of the extraction kicker field and optical aberration. Finally, the momentum tail was for the first time observed by implementing a novel scheme of vertical dispersion adjustment and was found to be qualitatively consistent with the presence of Touschek scattering. A possible scenario for horizontal beam halo formation from Touschek scattering was also suggested.
|
390 |
Testovací modul pro vybranou část standardu IEEE 802.1Q / Tester for chosen sub-standard of the IEEE 802.1QAvramović, Nikola January 2019 (has links)
Tato práce se zabývá analyzováním IEEE 802.1Q standardu TSN skupiny a návrhem testovacího modulu. Testovací modul je napsán v jazyku VHDL a je možné jej implementovat do Intel Stratix® V GX FPGA (5SGXEA7N2F45C2) vývojové desky. Standard IEEE 802.1Q (TSN) definuje deterministickou komunikace přes Ethernet sít, v reálném čase, požíváním globálního času a správným rozvrhem vysíláním a příjmem zpráv. Hlavní funkce tohoto standardu jsou: časová synchronizace, plánování provozu a konfigurace sítě. Každá z těchto funkcí je definovaná pomocí více různých podskupin tohoto standardu. Podle definice IEEE 802.1Q standardu je možno tyto podskupiny vzájemně libovolně kombinovat. Některé podskupiny standardu nemohou fungovat nezávisle, musí využívat funkce jiných podskupin standardu. Realizace funkce podskupin standardu je možná softwarově, hardwarově, nebo jejich kombinací. Na základě výše uvedených fakt, implementace podskupin standardu, které jsou softwarově související, byly vyloučené. Taky byly vyloučené podskupiny standardů, které jsou závislé na jiných podskupinách. IEEE 802.1Qbu byl vybrán jako vhodná část pro realizaci hardwarového testu. Různé způsoby testování byly vysvětleny jako DFT, BIST, ATPG a další jiné techniky. Pro hardwarové testování byla vybrána „Protocol Aware (PA)“technika, protože tato technika zrychluje testování, dovoluje opakovanou použitelnost a taky zkracuje dobu uvedení na trh. Testovací modul se skládá ze dvou objektů (generátor a monitor), které mají implementovanou IEEE 802.1Qbu podskupinu standardu. Funkce generátoru je vygenerovat náhodné nebo nenáhodné impulzy a potom je poslat do testovaného zařízeni ve správném definovaném protokolu. Funkce monitoru je přijat ethernet rámce a ověřit jejich správnost. Objekty jsou navrhnuty stejným způsobem na „TOP“úrovni a skládají se ze čtyř modulů: Avalon MM rozhraní, dvou šablon a jednoho portu. Avalon MM rozhraní bylo vytvořeno pro komunikaci softwaru s hardwarem. Tento modul přijme pakety ze softwaru a potom je dekóduje podle definovaného protokolu a „pod-protokolu “. „Pod-protokol“se skládá z příkazu a hodnoty daného příkazu. Podle dekódovaného příkazu a hodnot daných příkazem je kontrolovaný celý objekt. Šablona se používá na generování nebo ověřování náhodných nebo nenáhodných dat. Dvě šablony byly implementovány pro expresní ověřování nebo preempční transakce, definované IEEE 802.1Qbu. Porty byly vytvořené pro komunikaci mezi testovaným zařízením a šablonou podle daného standardu. Port „generátor“má za úkol vybrat a vyslat rámce podle priority a času vysílaní. Port „monitor“přijme rámce do „content-addressable memory”, která ověřuje priority rámce a podle toho je posílá do správné šablony. Výsledky prokázaly, že tato testovací technika dosahuje vysoké rychlosti a rychlé implementace.
|
Page generated in 0.1643 seconds