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Redes de metrologia: um estudo de caso da rede de defesa e segurança do SIBRATEC / Metrology network: a case study on the metrology network of defense and security from SIBRATECPereira, Marisa Ferraz Figueira 23 February 2016 (has links)
Nesta pesquisa, objetivou-se entender os efeitos da possível melhoria da infraestrutura laboratorial dos laboratórios da Rede de metrologia de defesa e segurança (RDS) do Programa Sibratec e da atuação da gestão em rede na oferta de apoio e de serviços metrológicos às empresas do setor de defesa e segurança, dentro dos propósitos do projeto. Procurou-se também identificar a existência de lacunas na oferta de serviços de calibração/ensaio para suprir a demanda das indústrias de defesa e segurança, bem como analisar a adequação do projeto RDS a essas demandas das indústrias de defesa e segurança, tendo como propósito contribuir com informações para ações futuras. A pesquisa desenvolvida é do tipo qualitativo, com características de pesquisa exploratória, fundamentada em estudo de caso. Foi estruturada em duas partes, envolvendo coleta de dados primários e de dados secundários. Para a coleta dos dados primários foram elaborados dois questionários, sendo um (Questionário A) destinado aos cinco representantes dos laboratórios na RDS e outro (Questionário B) aos contatos das 63 empresas do setor de defesa e segurança que necessitam de serviços de calibração e de ensaios pertinentes às áreas de atuação dos laboratórios da RDS. Foram obtidas respostas de quatro representantes dos laboratórios da RDS e de 26 empresas do setor de defesa e segurança. Os dados secundários resultaram de pesquisa documental. A análise dos resultados foi feita tendo por base cinco dimensões definidas com o objetivo de organizar e melhorar o entendimento do cenário da pesquisa. São elas, abrangência do projeto, regionalidade, gestão em rede, rastreabilidade metrológica e importância e visibilidade da RDS. Os resultados indicaram que a atuação da RDS não interferiu, até então, na rastreabilidade metrológica dos produtos das empresas do setor de defesa e segurança participantes da pesquisa. / This study is focused on understanding the effects of the infrastructure improvement of these laboratories and the role of network management in offering support and metrological services to the defense and security sector enterprises, within the project purposes. It is also aimed identify gaps on offering calibration and, or testing services to supply demands of the defense and security industries, and analyze adequacy of RDS project to demands of defense and security industries, with the purpose to contribute with information for future actions. The experimental research is qualitative type, with exploratory research characteristics, based on case study. It was structured in two parts, involving primary data collection and secondary data. In order to collect the primary data two questionnaires were prepared, one (Questionnaire A) to the five RDS laboratories representatives and other (Questionnaire B) to the contacts of 63 defense and security enterprises which need calibration and test services, possible customers of RDS laboratories. Answers from four representatives of RDS laboratories and from 26 defense and security enterprises were obtained. The collection of secondary data was obtained from documentary research. The analysis was made based on five dimensions defined in order to organize and improve the understanding of the research setting. They are RDS project coverage, regional, network management, metrological traceability and importance and visibility of RDS. The results indicated that the performance of RDS does not interfere, by that time, in the metrological traceability of the products of the defense and security enterprises that participated in the research.
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Redes de metrologia: um estudo de caso da rede de defesa e segurança do SIBRATEC / Metrology network: a case study on the metrology network of defense and security from SIBRATECMarisa Ferraz Figueira Pereira 23 February 2016 (has links)
Nesta pesquisa, objetivou-se entender os efeitos da possível melhoria da infraestrutura laboratorial dos laboratórios da Rede de metrologia de defesa e segurança (RDS) do Programa Sibratec e da atuação da gestão em rede na oferta de apoio e de serviços metrológicos às empresas do setor de defesa e segurança, dentro dos propósitos do projeto. Procurou-se também identificar a existência de lacunas na oferta de serviços de calibração/ensaio para suprir a demanda das indústrias de defesa e segurança, bem como analisar a adequação do projeto RDS a essas demandas das indústrias de defesa e segurança, tendo como propósito contribuir com informações para ações futuras. A pesquisa desenvolvida é do tipo qualitativo, com características de pesquisa exploratória, fundamentada em estudo de caso. Foi estruturada em duas partes, envolvendo coleta de dados primários e de dados secundários. Para a coleta dos dados primários foram elaborados dois questionários, sendo um (Questionário A) destinado aos cinco representantes dos laboratórios na RDS e outro (Questionário B) aos contatos das 63 empresas do setor de defesa e segurança que necessitam de serviços de calibração e de ensaios pertinentes às áreas de atuação dos laboratórios da RDS. Foram obtidas respostas de quatro representantes dos laboratórios da RDS e de 26 empresas do setor de defesa e segurança. Os dados secundários resultaram de pesquisa documental. A análise dos resultados foi feita tendo por base cinco dimensões definidas com o objetivo de organizar e melhorar o entendimento do cenário da pesquisa. São elas, abrangência do projeto, regionalidade, gestão em rede, rastreabilidade metrológica e importância e visibilidade da RDS. Os resultados indicaram que a atuação da RDS não interferiu, até então, na rastreabilidade metrológica dos produtos das empresas do setor de defesa e segurança participantes da pesquisa. / This study is focused on understanding the effects of the infrastructure improvement of these laboratories and the role of network management in offering support and metrological services to the defense and security sector enterprises, within the project purposes. It is also aimed identify gaps on offering calibration and, or testing services to supply demands of the defense and security industries, and analyze adequacy of RDS project to demands of defense and security industries, with the purpose to contribute with information for future actions. The experimental research is qualitative type, with exploratory research characteristics, based on case study. It was structured in two parts, involving primary data collection and secondary data. In order to collect the primary data two questionnaires were prepared, one (Questionnaire A) to the five RDS laboratories representatives and other (Questionnaire B) to the contacts of 63 defense and security enterprises which need calibration and test services, possible customers of RDS laboratories. Answers from four representatives of RDS laboratories and from 26 defense and security enterprises were obtained. The collection of secondary data was obtained from documentary research. The analysis was made based on five dimensions defined in order to organize and improve the understanding of the research setting. They are RDS project coverage, regional, network management, metrological traceability and importance and visibility of RDS. The results indicated that the performance of RDS does not interfere, by that time, in the metrological traceability of the products of the defense and security enterprises that participated in the research.
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A Probing System with Replaceable Tips for Three Dimensional Nano-MetrologyMrinalini, R Sri Muthu January 2017 (has links) (PDF)
With increase in the number of three dimensional (3-D) nanometer-scale objects that are being either fabricated or studied, there is a need to accurately characterize their geometry. While the Atomic force microscope (AFM) is a versatile tool for performing nano-metrology, it suffers from issues of poor accessibility of 3-D features and inability to measure 3-D forces that limit its applicability in 3-D nano-metrology. This thesis investigates the design and development of a novel probing system based on AFM that improves accessibility and enables direct measurement of 3-D forces acting on the AFM tip.
Two approaches are investigated to address the issue of poor accessibility. The first is to develop a novel system that enables in-situ replacement and reuse of specialized AFM tips that improve accessibility, and the second is to design a special AFM tip that can actively re-orient about two independent axes.
In order to perform in-situ tip replacement, a liquid meniscus based micro-gripper is developed and integrated on to a conventional AFM probe. The stiffness of the gripper is analyzed and shown to be adequately high along all three axes for AFM imaging to be performed. Tip replacement and re-use are both experimentally demonstrated by employing a novel tip-exchange station. The replaced tips are employed to show artifact-free AFM imaging of a standard calibration grating in both tapping-mode and contact-mode.
To actively re-orient a conventional tip, a novel magnetically-actuated micro-scale ball-and-socket joint is integrated onto an AFM probe. The quasi-static behavior of the joint is experimentally characterized, and the ability of the tip to independently re-orient about two axes is demonstrated. The achieved range is about +/- 90 degrees about both X- and Y-axes.
In order to realize the potential of the proposed probes for 3-D nano-metrology, an AFM is developed in-house that possesses the capability to make direct measurement of 3-D forces. Optimization of the measurement system to achieve identical sensitivities and resolution along all three axes is studied. Subsequently, the necessary electronics for measurement, actuation and control are developed. All the subsystems are experimentally calibrated and integrated. The overall AFM is shown to have a resolution of about 0.2 nm when operated in tapping-mode. The developed AFM is employed to showcase the following applications: characterization of the coefficient of kinetic friction of Muscovite mica, force controlled nano-scribing on polymethyl methacrylate (PMMA) and tapping-mode imaging of a calibration grating with the developed re-orientable AFM probe. Finally, the unique ability of the re-orientable AFM probe to control its tip-orientation is employed to develop a nanometer-scale coordinate measurement machine (CMM). The developed nano-CMM is shown to access the vertical wall of a sample and obtain its topography.
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THE FUTURE OF SUSTAINABILITY AND QUALITY IN CAR INTERIORSTraspel, Timm January 2022 (has links)
No description available.
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An investigation into enabling industrial machine tools as traceable measurement systemsVerma, Mayank January 2016 (has links)
On-machine inspection (OMI) via on-machine probing (OMP) is a technology that has the potential to provide a step change in the manufacturing of high precision products. Bringing product inspection closer to the machining process is very attractive proposition for many manufacturers who demand ever better quality, process control and efficiency from their manufacturing systems. However, there is a shortness of understanding, experience, and knowledge with regards to efficiently implementing OMI on industrially-based multi-axis machine tools. Coupled with the risks associated to this disruptive technology, these are major obstacles preventing OMI from being confidently adopted in many high precision manufacturing environments. The research pursued in this thesis investigates the concept of enabling high precision machine tools as measurement devices and focuses upon the question of: “How can traceable on-machine inspection be enabled and sustained in an industrial environment?” As highlighted by the literature and state-of-the-art review, much research and development focuses on the technology surrounding particular aspects of machine tool metrology and measurement whether this is theory, hardware, software, or simulation. Little research has been performed in terms of confirming the viability of industrial OMI and the systematic and holistic application of existing and new technology to enable optimal intervention. This EngD research has contributed towards the use of industrial machine tools as traceable measurement systems. Through the test cases performed, the novel concepts proposed, and solutions tested, a series of fundamental questions have been addressed. Thus, providing new knowledge and use to future researchers, engineers, consultants and manufacturing professionals.
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[en] STANDARDIZATION IN METROLOGY FOR THE THE BRAZILIAN AIR FORCE: DIAGNOSIS AND PROPOSAL OF AN INTEGRATED MODEL / [pt] NORMALIZAÇÃO EM METROLOGIA NO COMANDO DA AERONÁUTICA: DIAGNÓSTICO E CONSIDERAÇÕES SOBRE UM MODELO INTEGRADOELIZETE GONCALVES LOPES RANGEL 27 June 2005 (has links)
[pt] Tendo como motivação a consolidação futura de um sistema
integrado de
metrologia para o Ministério da Defesa, a presente
dissertação de mestrado
diagnostica e propõe uma re-estruturação do sistema
normativo do Sistema de
Metrologia Aeroespacial (SISMETRA) pertencente ao Comando
da Aeronáutica
(COMAER). O sistema normativo em metrologia do SISMETRA,
foco deste
trabalho, tem como atribuição emitir normas técnicas (NTS)
que padronizem a
execução das atividades relacionadas com a metrologia no
âmbito do COMAER.
Fundamentado em ampla pesquisa bibliográfica e no
diagnóstico do acervo
normativo de Normas Técnicas do SISMETRA (NTS), foi
possível mapear os
principais sub-processos existentes no desenvolvimento de
uma NTS e propor
uma sistemática alternativa mais ágil e mais eficiente.
Dois projetos de normas,
elaborados segundo a nova filosofia proposta e com o
objetivo de sistematizar os
sub-processos existentes na criação de uma NTS, foram
desenvolvidos como
estudos de caso para comprovar a eficiência e eficácia do
método proposto. O
trabalho analisou, também, a conformidade do acervo
normativo do SISMETRA
a procedimentos internos e preceitos estabelecidos em
normas nacionais e
internacionais. Como fundamentos básicos do diagnóstico, a
análise tomou
como substrato os princípios internacionais da normalização
e o Standard
Code, conforme caracterizado no Anexo 3 do Acordo de
Barreiras Técnicas ao
Comércio da Organização Mundial do Comércio. A análise
investigou a
aderência das NTS ao ABNT Guia 2 (Normalização e atividades
relacionadas -
vocabulário geral) e a ABNT ISO/IEC Diretiva Parte 3
(Redação e apresentação
de Normas Brasileiras) e a lógica processual relacionada ao
desenvolvimento,
adoção e aplicação de normas no âmbito do SISMETRA. No
âmbito de uma
pesquisa de demanda por normas em metrologia realizada
junto aos quarenta e
três (43) laboratórios de calibração que integram o
SISMETRA em todo o
território nacional, o trabalho identificou lacunas e
deficiências no sistema
vigente. Como resultado foram identificados 69 novos
títulos de
normas/procedimentos necessários para suprir
vulnerabilidades e/ou atribuir
maior racionalidade a sua operação. O desenvolvimento da
pesquisa de demanda por normalização em metrologia,
conduzida no âmbito do SISMETRA,
de per se, já estimulou ampla reflexão sobre a relevância
da atividade de
normalização nos laboratórios do SISMETRA sediados em todo
o território
nacional. Este sistema é tomado como modelo para proposição
de ações futuras
visando a implementação de um sistema normativo integrado.
Entendido como
estratégico subsídio para planejamento futuro, acredita-se
que o trabalho possa
colaborar para o desenvolvimento de um sistema de
metrologia integrado para o
atual Ministério da Defesa. / [en] Motivated by the future consolidation of an integrated
metrology system for
the Brazilian Defense Department, the present master s
degree dissertation
diagnoses and proposes the restructuring of SISMETR s
(Aerospace Metrology
System) standardization system, which is part of the
Brazilian Air Force
(COMAER). SISMETRA s standardization system, focus of this
master s degree
research, issues technical standards to govern the
activities related to metrology
within the Brazilian Air Force s scope. Based on a wide
bibliographic research
and on the diagnosis of SISMETRA s technical standards
(NTS) collection, it was
possible to map the main processes underlaid in an NTS and
proposed more
agile and efficient procedure. Two sets of standards were
prepared, according to
the new proposed philosophy, as case study to prove the
efficiency of the
proposed method. This master s degree research also
analyzed the conformity of
SISMETRA s technical standards (NTS) in conformity with
internal features and
precepts established on national and international
standards. As a basis to the
diagnosis, the study took as substratum the international
principles and the
Standard Code, as characterized in Annex 3 of the Agreement
on Technical
Barriers to Trade, of the World Trade Organization (WTO).
The study
contemplated the adherence of SISMETRA s Technical
Standards (NTS) to the
Brazilian Standards (ABNT) Guide 2 and ABNT ISO/IEC
Directive - Part 3 as
well as the logic that lays underneath the development, the
adoption and the
application of norms within the scope of the Brazilian Air
Force system s
metrology. As a result of a survey on demand for metrology
standards performed
at the 43 calibrations laboratories which integrate
SISMETRA nationwide, this
master s degree research carried out a thorough review of
the pros and cons of
the existing system, and 69 titles of standards/procedures
needed to reduce (or
overcome) vulnerabilities and/or to improve its operation.
The development of the
undertaken survey on demand for standards in metrology, by
itself, have
stimulated a wide reflection and awareness on the
importance of the
standardization within SISMETRA s laboratories nationwide.
This system is
considered a model for future actions to erect an
integrated standardization system. Seen as strategic
subsidy, this master s degree research work may
contribute to a future development of an integrated
metrology system to meet the
Ministry of Defense s needs.
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Étude de la connectivité Internet de l’île de la Réunion / Study of the Internet connectivity of Reunion IslandNoordally, Rehan 30 August 2018 (has links)
L'accès à Internet des îles de la Zone Océan Indien a la particularité d’utiliser deux longs câbles sous-marins. Les routes ont en commun de passer par un de ces liens et d’introduire une composante de délai qui peut être significative. La performance de TCP est liée à l’état des routes et au délai. Dans la situation de l'île de la Réunion, comment se comporte un protocole ayant une dépendance au délai tel que TCP ? Dans cette thèse, nous proposons une étude de l'Internet à La Réunion. Les travaux visent à pouvoir dresser un bilan de la connectivité Internet. Ils s'orientent d'une part à caractériser la connectivité au niveau du réseau et d'autre part à traduire ses caractéristiques au niveau de la couche de transport. Ainsi, les travaux présentés reposent sur deux études de métrologie sur le réseau réunionnais. Le premier examen a pour objectif la caractérisation des délais et des routes empruntées depuis et en direction de l'île. Ces travaux reposent sur une plate-forme de mesures mise en place à cet effet. Un outil d'identification des routes a été développé afin d'analyser les chemins depuis et vers la Réunion. Cet outil utilise une base de données de géolocalisation construite à partir des adresses IP rencontrées, des délais associés et d'informations provenant des Registres Internet Régionaux. L’analyse des résultats montre des caractéristiques propres à la région Réunion. La seconde étude de métrologie vise l'analyse des flux TCP. Des métriques associées à l'observation des captures de trafic sont identifiées afin d’établir les performances de TCP mais également les types de trafic entrant et sortant de l'île. Le volume des écoutes étant important, un outil d'analyse pour des traitements efficaces et rapides a également été développé. Les contributions de cette thèse sont d'abord rattachées au contexte réunionnais et sont extrapolées vers l'internet de la Zone Océan Indien. Cette thèse se veut être un élément pour une réflexion avec l'ensemble des acteurs de l'Internet à La Réunion. / The access to the Internet of the Islands of the Indian Ocean Area has the particularity of using two long submarines cables. The routes have in common to go through one of these links and introduce a delay component that can be significant. The performance of TCP is linked to the state of the route and the delay. In the situation of Reunion Island, how does a protocol having a dependence on delay such as TCP behaves? In this thesis, we propose a study of the Internet in Reunion Island. The work aims to be able to take stock of Internet connectivity. They are oriented on the one hand to characterize the connectivity at the level of the network and on the other hand to translate these characteristics at the level of the transport layer. Thus, the works presented are based on two metrology studies on the Reunion network. The first review aims to characterize the delays and the routes taken from and to the island. This work is based on a platform of measures put in place for this purpose. A road identification tool has been developed to analyze roads to and from Reunion Island. This tool uses a geolocation database built from IP addresses encountered, associated delays and information from the Regional Internet Registries. The analysis of the results shows characteristics specific to the Réunion region. The second metrology study aims to analyze TCP flows. Metrics associated with the observation of the catches of traffic are identified in order to establish the performances of TCP but also the types of traffic entering and leaving the island. Since the volume of the intercepts is important, an analysis tool for efficient and rapid treatments has been developed. The contributions of this thesis are first of all related to the Reunionese context and are extrapolated to the Internet of the Indian Ocean Zone. This thesis is meant to be an element for a reflection with all the actors of the Internet in Reunion Island.
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[pt] AVALIAÇÃO METROLÓGICA DA INFLUÊNCIA DA LARGURA DE JANELA DE UM DETECTOR DE FÓTONS ÚNICOS POR MEIO DE ATENUAÇÃO ÓPTICA / [en] METROLOGICAL EVALUATION OF THE INFLUENCE OF THE GATE WIDTH OF A SINGLEPHOTON DETECTOR BY OPTICAL ATTENUATIONVITOR SILVA TAVARES 01 September 2020 (has links)
[pt] Detectores de fótons únicos baseados em fotodiodos de avalanche (SPADs) são essenciais em aplicações que requerem alta resolução, como comunicações quânticas e metrologia quântica. O efeito da largura de janela de detecção temporal de fótons é pouco explorado, e não há estudos para a faixa de comprimentos de onda de interesse em telecomunicações em torno de: 1550 nm. Neste trabalho, apresenta-se uma proposta para análise de impacto da largura de janela de detecção de um SPAD de InGaAs/InP, realizando uma análise da estatística entre detecções consecutivas e da probabilidade de detecção de 0 ou 1 evento em função da atenuação óptica. Variou-se o número médio de fótons por janela medido pelo SPAD, e os resultados foram avaliados para os valores de 4 ns, 8 ns, 12 ns, 16 ns e 20 ns de largura de janela de detecção, sendo estimada a Incerteza de Medição Expandida para cada ensaio. Os resultados obtidos indicam uma faixa adequada de potência óptica para calibração de um SPAD com eficiência de detecção de 15 porcento e um tempo morto de 1 microssegundo, no intervalo de 10 nW a 0,15 nW. Nesta faixa de potência, os respectivos produtos associados ao efetivo número médio de fótons por janela de detecção correspondem aos valores de 190 x 10-(4) a 0,32 x 10(-4) (para 4 ns) e 140 x 10(-4) a 2,9 x 10(-4) (para 8 ns). Foram obtidos comportamentos lineares para os ajustes das curvas de calibração para larguras de janela de 4 ns e 8 ns. / [en] Single photon detectors based on avalanche photodiodes (SPADs) are essential in applications that require high resolution, such as quantum communications and quantum metrology. The effect of the width of photon detection gate is little explored, and there are no studies for the wavelength range of interest in telecommunications around 1550 nm. In this work, a proposal is presented for analyzing the impact of the detection gate width of an InGaAs/InP SPAD, performing a statistical analysis of consecutive detections and the probability detection of 0 or 1 events depending on the optical attenuation. The average number of photons per gate measured by the SPAD was varied, and the results were evaluated for the values of 4 ns, 8 ns, 12 ns, 16 ns and 20 ns of detection gate widths, and Expanded Measurement Uncertainty was estimated for each test. The results obtained indicate an adequate optical power range for calibrating a SPAD with a detection efficiency of 15 percent and dead – time of 1 microssecond, in the range of 10 nW to 0,15 nW. In this power range, the respective products, which are associated with an effective average number of photons per gate window, correspond to the values of 190 x 10(-4) to 0,32 x 10(-4) (for 4 ns) e 140 x 10(-4) to 2,9 x 10(-4) (for 8 ns). Linear behaviors were obtained for the adjustment of the calibration curves for gate widths of 4 ns and 8 ns.
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Improvements to Whole Lens Reconstruction for Saline Submerged Soft Contact LensesGuido, Christopher James January 2016 (has links)
A method for measuring the thickness and surface profiles of soft contact lenses while submerged in a saline solution has been implemented utilizing a low coherence Twyman-Green Interferometer. Although the original measurements demonstrated that features on the contact lens surfaces could be accurately determined, it was believed that the layout of the system also induced surface profile distortions. A new opto-mechanical layout has been implemented which eliminates many of these low frequency distortions. Improvements to the original phase unwrapping algorithms have also been developed to overcome the low visibility output inherent to the measurement allowing for a more complete analysis of the two surfaces of a contact lens.
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Reverberation chamber time and frequency metrology for MeerKAT systems shielding evaluationAndriambeloson, Joely Andrianina 12 1900 (has links)
Thesis (PhD)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: Electromagnetic shielding plays a significant role in the protection of electronic equipment.
Its application is essential for mitigating radio-frequency interference for the Karoo Array
Telescope (MeerKAT) project in the Karoo region of the Northern Cape. In this context,
time-domain (TD) methodology for small enclosure shielding effectiveness (SE) is developed
using a reverberated environment technique. Interest revolves around measurement time
speed-up and an extended SE response which covers the under-moded condition of small
enclosures. Recommended IEC standard 61000-4-21 [1] e ciency of 0.75, for log-periodic
dipole array (LPDA) antenna, is also validated from a reverberation chamber (RC)
characterisation of a printed circuit-board (PCB) LPDA e ciency.
A built-in pulse generator and the Square Kilometre Array (SKA) receiver RATTY form
the main elements of the TD metrology. For validation purpose, a reference coaxial airline
is built. The cable is characterised with computational codes (CST and FEKO) and is
also modelled with Vance and Kley's analytical expressions. The results are compared
with TD transfer impedance (Zt) measurement within the RC. The study shows that the
cable fixture within an RC shapes the cable under-test (CUT) Zt. The airline itself is
also introducing an oscillating component within Zt. The resonance is proportional to the
CUT length and it is visible within the measurement data and the simulations. It is not,
however, taken into account by the theoretical models.
The consequence of an incorrect antenna efficiency on RC applications is also addressed
using a PCB LPDA antenna efficiency investigation. The unknown LPDA is simulated
with CST for the study. The result is compared to an RC measurement validating the IEC
61000-4-21 standard efficiency recommendation of 0.75 [1]. This methodology characterised
the unknown antenna parameter from a reference dipole antenna efficiency we investigated
with FEKO. Simulated Wheeler-cap techniques permitted the reference antenna validation.
We found that an inaccurate LPDA efficiency has little effect at higher frequency if the
IEC efficiency is adopted. However, a difference of more than 7 dB can arise at low
frequency if the real efficiency differs by more than 0.3 with respect to the IEC value.
The study highlights the importance of a correct antenna efficiency for accurate RC
applications. The nested-enclosure technique is regarded as the conventional method of investigating
small enclosures SE [2]. The technique is in general time-consuming and works for a frequency range higher than three times the enclosure under test (EUT) lowest cut-o
value. Our TD metrology covers a frequency band up to 1.4 GHz which coincides with
our enclosure under-moded region. The SE characterisation is not well-documented
within this particular region. The dissertation contributes to this field using a non-stirred
nested-enclosure configuration. In contrast to the conventional use of the nested-enclosure
methodology [2], the source is placed here within the EUT and the enclosure is treated as
a normal radiator. The SE definition according to the IEEE standard in [2] is followed
and the enclosure total transferred-power is computed from the port's reflection coeficient.
The approach does not require a stirrer for the EUT. Our measurement shows an SE
agreement between the modfied and the appropriate nested-enclosure technique from 390
MHz up to 4 GHz. The investigation is faster, but in addition the TD spectrum gives a
more detailed SE response than the FD approach. / AFRIKAANSE OPSOMMING: Elektromagnetiese skerming speel n belangrike rol in die beskerming van elektroniese
komponente. Die toepassing daarvan is noodsaaklik vir die versagting van radiofrekwensie
steurings in die Karoo Array Telescope (MeerKAT) projek wat tans ontwikkel word in die
Karoo omgewing van die Noord-Kaap. In hierdie konteks is daar op n tydsgebied metode
vir klein-omhulsel beskermingse ektiwiteit (BE) gefokus, deur gebruik te maak van n
weerkatingsomgewing tegniek. Die belangstelling handel om metingstye te verkort en n
uitgebreide BE reaksie wat die lae-modus toestand van klein omhulsels dek. Aanbeveelde
International Electrotechnical Commission (IEC) standaard 61000-4-21 [2] e ektiwiteit
van 0.75, vir log-periodiese dipool-skikking (LPDA) antennas, is ook bekragtig deur n
weerkaatsingskamer karakterisering van n gedrukte-stroombaanbord (PCB) LPDS antenna
e ektiwiteit.
n Ingeboude impulsgenerator en die Square kilometre Array (SKA) ontvanger, RATTY,
vorm deel van die hoof elemente van die tydsgebiedmetings. Vir bekragtigings doeleindes
is n koaksiale lugtransmissielyn gebou. Hierdie kabel is gekarakteriseer deur numeriese
sagteware (CST en FEKO) en is ook gemoduleer met behulp van Vance en Kley se
analitiese uitdrukkings. Die resultate is vergelyk met tydsgebied-oordragsimpedansie (Zt)
metings, wat in die weerkaatsingskamer gedoen is. Die studie wys dat kabel posisie binne
in die weerkaatsingskamer die Zt van die kabel-onder-toets vervorm. Die lugstreep voeg
ook n ossillerende component by tot die gemete Zt. Die resonansie is eweredig aan die
lengte van die kabel en is duidelik sigbaar binne die meting- en simulasiedata. Dit is egter
nie in-berekening gebring in die analitiese modelle nie. Die gevolge van n verkeerde antenna e ektiwiteit in die weerkaatsingskamer toepassing is
ook aangespreek deur ondersoek na die e ektiwiteit van n PCB LPDA. Die onbekende
LPDA is gesimuleer met CST vir hierdie studie. Die resultate is vergelyk met n weerkaatsingskamer
meting, wat die IEC 61000-4-21 standaard e ektiwiteit van 0.75 [1] bekragtig.
Die metode karakteriseer die onbekende antenna veranderlike deur n verwysings dipool
antenna e ektiwiteit wat ge-ondersoek is in FEKO. Gesimuleerde Wheeler-cap tegnieke
het die veri kasie van die verwysings antenna resultate toegelaat. Daar is gevind dat
n onakkurate LPDA e ektiwiteit n klein e ek op die ho er frekwensies het, as die IEC
e ektiwiteit aangeneem is. Daar kan egter n verskil van 7dB voorkom by laer frekwensies,
as die werklike e ektiwiteit met meer as 0.3 van die IEC waarde verskil. Hierdie studie lig die belangrikheid van n korrekte antenna e ektiwiteit uit vir akkurate weerkaatsingskamer
toepassings.
Die geneste-omhulsel tegniek word beskou as die konvensionele metode vir die bestudering
van beskermingse ektiwiteit vir klein omhulsels. Die tegniek is gewoontlik tyd-rowend
en werk net vir frekwensies wat drie maal ho er is as die af-sny waarde van die omhulselonder-
toets. Ons tydgebiedmeting dek net n frekwensieband tot 1.4GHz, wat ooreenstem
met ons omhulsel lae-modus gebied. Die beskermingse ektiwiteit karakterisering, in
hierdie spesi eke veld, is nie goed gedokumenteer nie. Hierdie verhandeling dra by tot
hierdie veld deur gebruik te maak van n onversteurde geneste-omhulsel kon gurasie. In
teenstelling met die konvensionele gebruik van die geneste-omhulsel metode, is die bron
geplaas binne die omhulsel-onder-toets en word dit gebruik as n gewone uitstraler. Die
de nisie van beskermingse ektiwiteit volgens die IEEE standaard in [2], is gevolg en die
totale oordragskrag van die omhulsel is bereken deur gebruik te maak van n poort se
re
eksie ko e si ent. Die benadering benodig nie n steurder vir die omhulsel-onder-toets
nie. Ons metings se beskermingse ektiwiteit het ooreengestem met die veranderde - en
die geskikte geneste-omhulsel tegniek, van 390MHz tot 4GHz in die spektrum. Hierdie
ondersoek is vinniger en lewer n meer gedetailleerde beskermingse ektiwiteit reaksie as
die frekwensiegebied benadering.
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