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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Radiative emission from O←3 and HNO←3 in the middle atmosphere

Pemberton, David N. C. January 1993 (has links)
No description available.
2

The High Temperature Condensation Particle Counter (HT-CPC) : a new instrument for a measurement of solid particulate matter

Rongchai, Kanchit January 2014 (has links)
No description available.
3

Development of an electronic sensor for engine exhaust particulate measurements

Warey, Alok Arun 28 August 2008 (has links)
Not available / text
4

Porovnání emisních norem u motorů JCB

RYŠAVÝ, Tomáš January 2018 (has links)
The aim of this diploma thesis is to compare the latest emission standards for JCB engines that are used in JCB telescopic loaders. The first part of this work is focused on the history of JCB, the development of JCB Loadall telescopic loaders and also deals with issues of emissions, their origin, effects on humans and the atmosphere. In addition, there are listed ways how to reduce emissions, both ways of reducing pollutants by designing the combustion chamber and reducing them by systems such as SCR (Selective Catalytic Reduction), DOC (Diesel Oxidation Catalyst), EGR (Exhaust Gas Recirculation) and particulate filters. Emission regulations are included as well. The second part of this work is focused on the actual measurement of the exhaust gas emissions of JCB engines with different technologies for their reduction. The measured values will be further processed and inserted into tables and graphs that will then be compared to each other.
5

Capacitive Structures for Gas and Biological Sensing

Sapsanis, Christos 04 1900 (has links)
The semiconductor industry was benefited by the advances in technology in the last decades. This fact has an impact on the sensors field, where the simple transducer was evolved into smart miniaturized multi-functional microsystems. However, commercially available gas and biological sensors are mostly bulky, expensive, and power-hungry, which act as obstacles to mass use. The aim of this work is gas and biological sensing using capacitive structures. Capacitive sensors were selected due to its design simplicity, low fabrication cost, and no DC power consumption. In the first part, the dominant structure among interdigitated electrodes (IDEs), fractal curves (Peano and Hilbert) and Archimedean spiral was investigated from capacitance density perspective. The investigation consists of geometrical formula calculations, COMSOL Multiphysics simulations and cleanroom fabrication of the capacitors on a silicon substrate. Moreover, low-cost fabrication on flexible plastic PET substrate was conducted outside cleanroom with rapid prototyping using a maskless laser etching. The second part contains the humidity, Volatile Organic compounds (VOCs) and Ammonia sensing of polymers, Polyimide and Nafion, and metal-organic framework (MOF), Cu(bdc)2.xH2O using IDEs and tested in an automated gas setup for experiment control and data extraction. The last part includes the biological sensing of C - reactive protein (CRP) quantification, which is considered as a biomarker of being prone to cardiac diseases and Bovine serum albumin (BSA) protein quantification, which is used as a reference for quantifying unknown proteins.
6

An Investigation of Urban Mobile Source Aerosol Using Optical Properties Measured by CRDT/N: Diesel Particulate Matter and the Impact of Biodiesel

Wright, Monica Elizabeth 06 December 2012 (has links)
Mobile source emissions are a major contributor to global and local air pollution. Governments and regulatory agencies have been increasing the stringency of regulations in the transportation sector for the last ten years to help curb transportation sector air pollution. The need for regulations has been emphasized by scientific research on the impacts from ambient pollution, especially research on the effect of particulate matter on human health. The particulate emissions from diesel vehicles, diesel particulate matter (DPM) is considered a known or probable carcinogen in various countries and increased exposure to DPM is linked to increased cardiovascular health problems in humans. The toxicity of vehicle emissions and diesel particulate emissions in particular, in conjunction with an increased awareness of potential petroleum fuel shortages, international conflict over petroleum fuel sources and climate change science, have all contributed to the increase of biodiesel use as an additive to or replacement for petroleum fuel. The goal of this research is to determine how this increased use of biodiesel in the particular emission testing setup impacts urban air quality. To determine if biodiesel use contributes to a health or climate benefit, both the size range and general composition were investigated using a comprehensive comparison of the particulate component of the emissions in real time. The emissions from various biodiesel and diesel mixtures from a common diesel passenger vehicle were measured with a cavity ring-down transmissometer (CRDT) coupled with a condensation particle counter, a SMPS, a nephelometer, NOx, CO, CO2, and O3 measurements. From these data, key emission factors for several biodiesel and diesel fuel mixtures were developed. This approach reduces sampling artifacts and allows for the determination of optical properties, particle number concentration, and size distributions, along with several important gas phase species' concentrations. Findings indicate that biodiesel additions to diesel fuel do not necessarily have an air quality benefit for particulate emissions in this emission testing scenario. The often cited linear decrease in particulate emissions with increasing biodiesel content was not observed. Mixtures with half diesel and half biodiesel tended to have the highest particulate emissions in all size ranges. Mixtures with more than 50% biodiesel had slightly lower calculated mass for light absorbing carbon, but this reduction in mass is most likely a result of a shift in the size of the emission particles to a smaller size range, not a reduction in the total number of particles. Evaluation of the extensive optical properties from this experimental set-up indicates that biodiesel additions to diesel fuel has an impact on emission particle extinction in both visible and near-IR wavelengths. The B99 mixture had the smallest emission factor for extinction at 532 nm and at 1064 nm. For the extinction at 532 nm, the trend was not linear and the emission factor peaked at the B50 mixture. Results from intensive properties indicate that emissions from B5 and B25 mixtures have Ångström exponents close to 1, typical for black carbon emissions. The mixtures with a larger fraction of biodiesel have Ångström exponent values closer to 2, indicating more absorbing organic matter and/or smaller particle size in the emissions. Additional experimental testing should be completed to determine the application of these results and emission factors to other diesel vehicles or types of diesel and biodiesel fuel mixtures.
7

Development of acoustic sensors for the extension of measurements to high temperature in the experimental reactors / Développement de capteurs ultrasonores pour l’extension des mesures acoustiques aux hautes températures dans les réacteurs expérimentaux

Gatsa, Oleksandr 30 November 2018 (has links)
Ce travail de thèse porte sur l’étude et la réalisation d'une nouvelle génération de capteurs ultrasonore dédiés à la caractérisation des gaz de fission. Plus généralement, ces études concernent le développement de l’instrumentation du réacteur d’essai des matériaux Jules Horowitz (RJH), visant entre autre à effectuer le contrôle in situ de la composition du gaz libéré afin d’optimiser la durée de vie du combustible et le taux de combustion. La température de fonctionnement de ce nouveau réacteur devant se situer dans la plage entre 200 °C à 400 °C, la principale problématique concerne donc le développement d’un matériau piézoélectrique, capable de fonctionner dans la plage de température requise, et son intégration à un dispositif de détection.Nous proposons l’utilisation du sodium titanate de bismuth (NBT) développé par la méthode de la sérigraphie. Dans le but d'optimiser les conditions de fabrication des matériaux, plusieurs versions de matériaux piézoélectriques ont été produites au cours de cette thèse. Chacun des matériaux a été caractérisé (paramètres morphologiques, chimiques, électriques, diélectriques, piézoélectriques et électromécaniques) et des tests en fonction de la température ont été conduits. Après avoir démontré une bonne répétabilité dans la production du matériau, le protocole de fabrication des capteurs a été déterminé et un prototype de capteur ultrasonore a été réalisé.Ces capteurs ont été fabriqués par dépôt du matériau actif sur un substrat d'alumine. Après caractérisation des propriétés des capteurs, des essais ont montré une sensibilité acoustique importante à température ambiante. De plus, la possibilité d'une détection de gaz sur une gamme de pression de 50 à 70 bars a été démontrée par l'intégration d’un capteur dans une enceinte. Pour vérifier la possibilité d'application du capteur à la détection de gaz dans des environnements hostiles (haute température), un modèle théorique basé sur les propriétés électromécaniques et les équations d’adaptation d’impédance a été introduit. Il a été démontré théoriquement que le capteur est capable d'effectuer des mesures de gaz de la température ambiante jusqu’à 350 °C. / This Ph.D. thesis is dedicated to the development of a new generation of ultrasonic sensors devoted to fission gas characterization. More generally, these studies concern the development of instrumentation for the Jules Horowitz material testing reactor (JHR) aiming to perform in-situ control of the released gas composition for optimization of burn-up rate and fuel rod lifetime. The operation temperature of this new reactor will be in the range of 200 °C - 400 °C. Hence, the main problem concerns the development of piezoelectric material, able to operate in the required temperature range, and its integration with a sensor device.To resolve this problem, we propose to use the sodium bismuth titanate (NBT) ceramic material developed by the screen-printing technique. Several versions of piezoelectric materials were produced during this research, with the purpose of optimizing material manufacturing conditions Each material was characterized (morphological, chemical, electric, dielectric, piezoelectric and electromechanical parameters) and “tests as a function of temperature” were carried out. After demonstrating repeatability in material fabrication, the protocol for NBT sensor production was determined and a prototype of the ultrasonic sensor was fabricated.The sensor was fabricated by deposition of an active material onto an alumina substrate. After characterization of sensor properties, acoustic tests showed a high sensitivity of measurements at ambient temperature (25 °C). Furthermore, by integration of sensors into a pressurized enclosure the possibility of gas detection in the range from 50 to 70 bars was demonstrated. To verify the sensor’s applicability to gas detection under harsh temperature environment, a theoretical model based on electromechanical properties and impedance matching equations was introduced. It was theoretically demonstrated that the sensor is able to perform gas measurements from ambient temperature up to 350 °C.
8

Um sistema para estima??o da vaz?o de g?s de po?os produzindo por Plunger Lift para vaso separador de teste em plataformas de petr?leo

Silva, S?rgio Jos? Gon?alves e 13 November 2007 (has links)
Made available in DSpace on 2014-12-17T14:55:00Z (GMT). No. of bitstreams: 1 SergioJGS.pdf: 1164807 bytes, checksum: 597fe8700a95271ecd0c0f3e0b460362 (MD5) Previous issue date: 2007-11-13 / This work intends to analyze the behavior of the gas flow of plunger lift wells producing to well testing separators in offshore production platforms to aim a technical procedure to estimate the gas flow during the slug production period. The motivation for this work appeared from the expectation of some wells equipped with plunger lift method by PETROBRAS in Ubarana sea field located at Rio Grande do Norte State coast where the produced fluids measurement is made in well testing separators at the platform. The oil artificial lift method called plunger lift is used when the available energy of the reservoir is not high enough to overcome all the necessary load losses to lift the oil from the bottom of the well to the surface continuously. This method consists, basically, in one free piston acting as a mechanical interface between the formation gas and the produced liquids, greatly increasing the well s lifting efficiency. A pneumatic control valve is mounted at the flow line to control the cycles. When this valve opens, the plunger starts to move from the bottom to the surface of the well lifting all the oil and gas that are above it until to reach the well test separator where the fluids are measured. The well test separator is used to measure all the volumes produced by the well during a certain period of time called production test. In most cases, the separators are designed to measure stabilized flow, in other words, reasonably constant flow by the use of level and pressure electronic controllers (PLC) and by assumption of a steady pressure inside the separator. With plunger lift wells the liquid and gas flow at the surface are cyclical and unstable what causes the appearance of slugs inside the separator, mainly in the gas phase, because introduce significant errors in the measurement system (e.g.: overrange error). The flow gas analysis proposed in this work is based on two mathematical models used together: i) a plunger lift well model proposed by Baruzzi [1] with later modifications made by Bolonhini [2] to built a plunger lift simulator; ii) a two-phase separator model (gas + liquid) based from a three-phase separator model (gas + oil + water) proposed by Nunes [3]. Based on the models above and with field data collected from the well test separator of PUB-02 platform (Ubarana sea field) it was possible to demonstrate that the output gas flow of the separator can be estimate, with a reasonable precision, from the control signal of the Pressure Control Valve (PCV). Several models of the System Identification Toolbox from MATLAB? were analyzed to evaluate which one better fit to the data collected from the field. For validation of the models, it was used the AIC criterion, as well as a variant of the cross validation criterion. The ARX model performance was the best one to fit to the data and, this way, we decided to evaluate a recursive algorithm (RARX) also with real time data. The results were quite promising that indicating the viability to estimate the output gas flow rate from a plunger lift well producing to a well test separator, with the built-in information of the control signal to the PCV / Este trabalho se prop?e a realizar uma an?lise do comportamento da vaz?o de g?s de po?os produzindo por plunger lift para vasos separadores de teste em plataformas de produ??o de petr?leo com o objetivo de propor uma t?cnica de estima??o da vaz?o durante os instantes de golfadas provocadas por estes tipos de po?os. A motiva??o para este trabalho surgiu diante da perspectiva de instala??o pela PETROBRAS de alguns po?os equipados com plunger lift no campo mar?timo de Ubarana situado na costa do Rio Grande do Norte onde a medi??o dos volumes produzidos ? feita em vaso separador na plataforma. O m?todo de eleva??o artificial de petr?leo denominado plunger lift ? utilizado quando a energia dispon?vel no reservat?rio n?o ? suficiente para vencer todas as perdas de carga necess?rias para elevar o petr?leo do fundo do po?o at? a superf?cie de forma cont?nua. O m?todo consiste, basicamente, de um pist?o livre (plunger) agindo como uma interface mec?nica entre o g?s da forma??o e os l?quidos produzidos, aumentando enormemente a efici?ncia de eleva??o. ? instalada, tamb?m, uma v?lvula de controle acionada pneumaticamente, na linha de produ??o do po?o para efetuar o controle dos ciclos. Ao ser aberta a v?lvula, o pist?o se desloca do fundo do po?o at? a superf?cie, elevando o ?leo e o g?s que se encontram acima do mesmo at? chegar no vaso separador de teste onde os fluidos ser?o medidos. O vaso separador de teste ? utilizado para fazer a aferi??o dos volumes produzidos pelo po?o durante um determinado per?odo de tempo denominado de teste de produ??o. Na maioria dos casos, os vasos separadores s?o projetados para medi??o de vaz?es estabilizadas, ou seja, razoavelmente constantes atrav?s do uso de controladores eletr?nicos de n?vel e de press?o. No caso de po?os produzindo por plunger lift, as vaz?es de l?quido e de g?s na superf?cie s?o c?clicas e de amplitude vari?vel, acarretando o surgimento de golfadas no interior do vaso separador provocando, principalmente para o caso do g?s, erros significativos no sistema de medi??o (ex.: erro de overrange ). A an?lise da vaz?o de g?s proposta neste trabalho se baseia na integra??o de dois modelos matem?ticos: i) modelagem de um po?o de plunger lift proposta por Baruzzi [1] com modifica??es efetuadas posteriormente por Bolonhini [2] na implementa??o de um simulador de plunger lift; ii) modelagem de um vaso separador bif?sico (g?s + l?quido) a partir de um modelo trif?sico (?leo + g?s + ?gua) proposto por Nunes [3]. Com base nos modelos acima e utilizando-se dados coletados no vaso separador de teste da plataforma PUB-02 (campo de Ubarana), foi poss?vel demonstrar que a vaz?o de sa?da de g?s do vaso de teste pode ser estimada, com razo?vel precis?o, a partir do sinal de controle da v?lvula controladora de press?o (PCV). Diversos modelos dispon?veis no toolbox de Identifica??o de Sistemas do MATLAB? foram analisados para se avaliar qual seria o que melhor se adaptava aos dados coletados no campo. Para a valida??o dos modelos foi usado o crit?rio de AIC, bem como uma variante do crit?rio de valida??o cruzada. O modelo ARX foi o que apresentou melhor desempenho com base nos dados coletados e, desta forma, decidiu-se avaliar tamb?m um algoritmo recursivo (RARX) com dados obtidos em tempo real. Os resultados foram bastante promissores, indicando a viabilidade de se poder estimar a vaz?o de sa?da de g?s de um po?o de plunger lift produzindo para um vaso separador de teste a partir da informa??o contida no sinal de controle da PCV
9

Development of a novel sensor for soot deposition measurement in a diesel particulate filter using electrical capacitance tomography

Huq, Ragibul January 2014 (has links)
Indiana University-Purdue University Indianapolis (IUPUI) / This paper presents a novel approach of particulate material (soot) measurement in a Diesel particulate filter using Electrical Capacitance Tomography. Modern Diesel Engines are equipped with Diesel Particulate Filters (DPF), as well as on-board technologies to evaluate the status of DPF because complete knowledge of DPF soot loading is very critical for robust efficient operation of the engine exhaust after treatment system. Emission regulations imposed upon all internal combustion engines including Diesel engines on gaseous as well as particulates (soot) emissions by Environment Regulatory Agencies. In course of time, soot will be deposited inside the DPFs which tend to clog the filter and hence generate a back pressure in the exhaust system, negatively impacting the fuel efficiency. To remove the soot build-up, regeneration of the DPF must be done as an engine exhaust after treatment process at pre-determined time intervals. Passive regeneration use exhaust heat and catalyst to burn the deposited soot but active regeneration use external energy in such as injection of diesel into an upstream DOC to burn the soot. Since the regeneration process consume fuel, a robust and efficient operation based on accurate knowledge of the particulate matter deposit (or soot load)becomes essential in order to keep the fuel consumption at a minimum. In this paper, we propose a sensing method for a DPF that can accurately measure in-situ soot load using Electrical Capacitance Tomography (ECT). Simulation results show that the proposed method offers an effective way to accurately estimate the soot load in DPF. The proposed method is expected to have a profound impact in improving overall PM filtering efficiency (and thereby fuel efficiency), and durability of a Diesel Particulate Filter (DPF) through appropriate closed loop regeneration operation.

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