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1
Stander, Tinus. "High-power broadband absorptive waveguide filters." Thesis, Stellenbosch : University of Stellenbosch, 2009. http://hdl.handle.net/10019.1/1157.
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Thesis (PhD (Electrical and Electronic Engineering))--University of Stellenbosch.ENGLISH ABSTRACT: This dissertation presents a synthesis method for broadband high-power absorptive microwave lters by cascading a wide stop-band wa e-iron lter with an absorptive harmonic pad. The classical image impedance synthesis methods for wa e-iron lters are updated to allow for non-uniform boss patterns, which enable control over both the stop-band attenuation and pass-band re ection of the lter. By optimising an accurate circuit model equivalent, computationally intensive numerical EM optimisation are avoided. The nonuniform wa e-iron lter achieves the same electrical speci cation as similar lters in literature, but in a smaller form factor. The prototype presented displays less than -21 dB in-band re ection over 8.5 - 10.5 GHz, with stop-band attenuation in excess of 50 dB over the harmonic bands 17 - 31.5 GHz and 30 dB over the 34 - 42 GHz. The prototype is designed to handling 4 kW peak power incident in the transmitted band, and is 130 mm in length. Minimal full-wave tuning is required post-synthesis, and good agreement is found between synthesised and measured responses. Additionally, a completely novel oblique wa e-iron boss pattern is proposed. For the absorptive harmonic pad, transversal broadwall slots in rectangular waveguide, coupling to an absorptive auxiliary guide, are investigated in the presence of standing wave surface current distributions. An accurate circuit model description of the cascaded structure is developed, and optimised to provide a required level of input match in the presence of an arbitrary re ective lter. Using numerical port parameter data of the wa eiron lter, a harmonic pad is developed that provides -12.5 dB input re ection match across the band 17 - 21 GHz with up to 1 kW peak incident power handling capability, yet is only 33 mm in length. Again, good agreement is found between synthesised and measured responses of the cascaded structure.
AFRIKAANSE OPSOMMING: Hierdie proefskrif stel 'n sintesetegniek voor vir wyeband, ho edrywing absorberende mikrogol lters deur 'n kaskade kombinasie van 'n verlieslose wafelyster lter met 'n wye stopband, en 'n absorberende harmoniekdemper. Die klassieke sintesemetodes vir wafelyster lters word aangepas om nie-uniforme tandpatrone toe te laat, wat beheer oor beide die lter se stopband attenuasie en deurlaatband weerkaatsing moontlik maak. Deur die optimering van 'n akkurate stroombaanmodel van die lter kan berekeningsintensiewe numeriese EM optimering vermy word. Die nieuniforme wafelyster lter behaal dieselfde spesi kasies as soortgelyke gepubliseerde lters, maar is meer kompak. Die vervaardigingsprototipe handhaaf minder as -21 dB intreeweerkaatsing oor die deurlaatband van 8.5 - 10.5 GHz, asook attenuasie van meer as 50 dB oor die stopband 17 - 31.5 GHz en 30 dB oor 34 - 42 GHz. Die prototipe is ontwerp om 4 kW intree kruindrywing te hanteer in die deurlaatband, en is 130 mm lank. Die metode vereis minimale verstellings tydens volgolf simulasie, en die meetresultate stem goed ooreen met die gesintetiseerde gedrag. 'n Nuwe skuinstandpatroon word ook voorgestel vir wafelyster lters. Vir die harmoniekdemper word transversale bre ewandgleuwe in reghoekige gol eier wat koppel na 'n absorberende newegol eier ondersoek in die teenwoordigheid van staandegolfpatrone in oppervlakstroom. 'n Akkurate stroombaanmodel van 'n gleufkaskade word ontwikkel, en geoptimeer om 'n vereiste intreeweerkaatsing te bewerkstellig in samewerking met 'n arbitr^ere weerkaatsende lter. Deur gebruik te maak van poortparameterdata van die wafelyster lter word 'n 33 mm lange hamoniekdemper ontwikkel wat 'n maksimum intreeweerkaatsing van -12.5 dB oor die band 17 - 21 GHz handhaaf vir kruindrywingsvlakke van tot 1 kW. Goeie ooreenstemming tussen gesintetiseerde en gemete resultate word weereens waargeneem vir die volledige saamgestelde struktuur.
2
Ben, Reddad Khalid. "Absorption percutanée et métabolisme de filtres solaires." Paris 11, 1994. http://www.theses.fr/1994PA11XXXX.
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Katskov, DA. "Graphite filter atomizer in atomic absorption spectrometry." Elsevier, 2006. http://encore.tut.ac.za/iii/cpro/DigitalItemViewPage.external?sp=1000798.
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Graphite filter atomizers (GFA) for electrothermal atomic absorption spectrometry (ETAAS) show substantial advantages over commonly
employed electrothermal vaporizers and atomizers, tube and platform furnaces, for direct determination of high and medium volatility elements in
matrices associated with strong spectral and chemical interferences. Two factors provide lower limits of detection and shorter determination cycles
with the GFA: the vaporization area in the GFA is separated from the absorption volume by a porous graphite partition; the sample is distributed
over a large surface of a collector in the vaporization area. These factors convert the GFA into an efficient chemical reactor. The research
concerning the GFA concept, technique and analytical methodology, carried out mainly in the author's laboratory in Russia and South Africa, is
reviewed. Examples of analytical applications of the GFA in AAS for analysis of organic liquids and slurries, bio-samples and food products are
given. Future prospects for the GFA are discussed in connection with analyses by fast multi-element AAS.
4
Thompson, Timothy V. "Solid-state NMR studies of absorption onto activated carbon." Thesis, Durham University, 1995. http://etheses.dur.ac.uk/5228/.
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This is a study of adsorption on three activated carbon substrates using solid- state NMR. The adsorbates used as probe molecules included a range of phosphates, phosphonates and deuterated water. High-resolution (^31)p and (^2)H NMR spectra have been obtained using magic-angle spinning and a single-pulse regime. The deuterium results include the generation of an adsorption isotherm. The traditional gravimetric analysis and NMR experiments were run concurrently. These results showed that the NMR technique was qualitatively and quantitatively accurate, while the proven adsorption isotherm theory could be applied to the NMR results. The additional information given by the (^2)H NMR results showed evidence of two distinct adsorption sites. Initial adsorption in the micropores gives a peak shifted by 6 ppm to low frequency of the liquid (^2)H(_2)O. This peak was broadened due to restricted motion in the micropores. The second peak was observed only at high relative humidities and was attributed to adsorption on the external surface or in macropores. The chemical shift was similar to that of the pure liquid. The (^31)p NMR results were used to directly observe the adsorption of phosphates with a range of molecular sizes. The NMR data were used to calculate the micropore accessibility for each phosphate. Differences in the adsorption mechanism were recorded, and direct comparison for each carbon gave some structural information. It was possible to follow competition reactions over time periods of 1 min to 24 hours. A battlefield simulation was studied, with (^2)H(_2)O and a phosphate competing for the adsorption sites. The NMR results showed that the phosphate was preferentially adsorbed into the micropores, displacing the (^2)H(_2)O However, the addition of (^2)H(_2)O to a carbon saturated with a phosphate enabled more phosphate to be adsorbed into the micropores via a cooperative mechanism. Measurements of the transverse relaxation for adsorbed molecules suggest that the broad micropore signal consists of some overlapping peaks. The peaks width similar chemical shift are attributed to adsorption in pores with differing dimensions. The natural linewidth involves broadening caused by restricted anisotropic motion within the micropores.
5
Shehata, Hussein A. H. "HVAC systems using flexible fibre impeller fans." Thesis, University of Nottingham, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.297764.
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Ngobeni, P., C. Canario, DA Katskov, and Y. Thomassen. "Transverse heated filter atomizer: atomic absorption determination of Pb and Cd in urine." Journal of Analytical Atomic Spectroscopy, 2003. http://encore.tut.ac.za/iii/cpro/DigitalItemViewPage.external?sp=1000894.
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A transverse heated filter atomizer (THFA) was applied to the direct determination of Cd and Pb in urine, and
its analytical performances were investigated using a PerkinElmer SIMAA 6000 atomic absorption
spectrometer. Seronorm certified human urine reference materials and six realistic samples collected locally were
used for the method validation. The urines were diluted ten- or five-fold with 0.2% HNO3. Cd and Pb nitrate
solutions were employed as standards. Recoveries of the elements from the urine samples were investigated with
the analyte addition method. Compared to the transverse heated graphite atomizer (THGA) with a platform,
the THFA provided a significant reduction of spectral background and chemical interferences from the urine
matrix, without the use of chemical matrix modifiers, a 1.5–2 times increase of the determination sensitivity
and, therefore, a reduction of limits of detection up to 0.018 and 0.2 mg L21 for Cd and Pb, respectively. The
use of a THFA collector made from carbon fiber and a tungsten wire improved recoveries of lead and
cadmium in urine (¢92%). A sampling temperature 150 uC enabled us to skip the drying period, thus a
significantly reduced temperature program was obtained. The accuracies of the measurements of Cd and Pb in
the Seronorm urine materials were in good agreement with the recommended values: 4.1 ¡ 0.1 mg L21 of Cd
(recommended 5) and 92 ¡ 1 mg L21 of Pb (recommended 85). The lifetime of the THFA for Pb determination
was longer than 700 firings, with the sensitivity loss not more than 25% after 500 firings.
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Huong, Srei Pisei. "Etude de la photostabilité et de l'absorption cutanée des filtres solaires." Aix-Marseille 2, 2008. http://www.theses.fr/2008AIX22955.
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Les produits de protection solaire font partie de l’arsenal nécessaire pour une protection indispensable contre les méfaits des rayonnements UV. Toutefois malgré leurs caractères indispensables, des risques potentiels existent : une photoinstabilité des filtres, avec la présence possible des produits de dégradation, une irrégularité de l’épaisseur du film protecteur appliqué induisant une protection diminuée, un passage de la barrière cutanée par les filtres ou par leurs produits de dégradation, une mauvaise utilisation du produit par le consommateur. La photoréactivité de deux filtres solaires éthylhexyl p-méthoxy cinnamate (OMC) et butylméthoxydibenzoylméthane (BMDBM ou DBM) ont été étudié dans différentes conditions, (i) en volume à l'aide de solutions diluées dans des solvants de polarité variable, (ii) en couche mince à l'aide de solutions concentrées dans des solvants nonvolatils et (iii) dans des produits solaires commerciaux. Pour l’OMC, la caractéristique spectroscopique de l’isomère Z a été déterminée, avec son facteur de réponse obtenue par Chromatographie Liquide à Haute Performance. Le rapport des deux isomères E et Z a été mesuré dans chaque état d'irradiation. L'incidence de la photoisomérisation sur le facteur de protection solaire (FPS) a été évaluée sur la base des calculs déduits du concept du film irrégulier. La diminution du FPS, qui peut excéder 30 %, dépend principalement du taux d'isomérisation de l’OMC mais également de la composition des produits de protection solaire. Puisque l'isomérisation de l’OMC est rapide et imprévisible, il est impossible d'obtenir une bonne corrélation entre les mesures du FPS in vivo et in vitro, si les mesures in vitro ne sont pas précédées du processus d'irradiation entraînant l'isomérisation de l'OMC. Pour le DBM, nous avons trouvé que sa sensibilité à la lumière dépend des conditions expérimentales. DBM est stable dans un solvant polaire tel que l'alcool, tandis que dans un solvant non polaire (Hexane), DBM subit un déplacement réversible de l’équilibre tautomérique. Ce phénomène inattendu est inhibé par une modification minime de la polarité du solvant. Les produits de photodégradations ont analysés par chromatographie liquide - spectromètre de masse (CLHP-SM), pour pouvoir les identifier, en détectant leurs masses moléculaires. L'incidence de la photodégradation sur la valeur du FPS a été mesurée. Les travaux sur la photoréactivité des filtres solaires OMC et DBM ont été publiés dans une revue internationale. L’étude in vitro du passage transdermique des filtres solaires et de leurs produits de dégradation est effectuée sur la peau de l’oreille de porc installée sur des cellules de diffusion. Elle démontre que l’absorption cutanée de ces deux filtres est très faibleThe sunscreen product belongs to the arsenal necessary for an essential protection against the harmful effect of UV radiations. Although their essential character, the potential risks exist: a photoinstability of the filters, with the possible presence of the breakdown products (photodegradation product), an irregularity thickness of protective film applied inducing a decreased protection, a passage of the cutaneous barrier by the filters or their breakdown products, a misuse of the product by the consumer. The photoisomerization of two sun filter ethylhexyl p-methoxycinnamate (OMC) and butylmethoxydibenzoylmethane (BMDBM or DBM) were studied under various conditions, (i) by irradiating diluted solutions using various solvents, (ii) by irradiating thin layers of concentrated solutions in non-volatile solvents, and (iii) by irradiating thinly applied commercial sunscreen products. The spectroscopic characteristics of the Z isomer were determined, along with its response factor in HPLC analysis. The ratio of the two isomers E and Z was measured under each condition of irradiation. The incidence of photoisomerization in the sun protection factor (SPF) was evaluated on the basis of calculations deduced from the concept of irregular film developed by O’Neill. The decrease in SPF, which can exceed 30%, is primarily dependent upon the rate of isomerization of OMC but also on the composition of sunscreen products. As isomerization of OMC is rapid and its rate unpredictable, it is in theory impossible to obtain good correlation between measurements of SPF in vivo and those in vitro, if measurements in vitro are not preceded by the process of irradiation precipitating isomerization of OMC. The behaviour of DBM clearly showed that its sensitivity to light is dependent on experimental conditions. DBM is stable in a polar solvent such as alcohol, whereas in a non-polar solvent (Hexane), DBM is undergoing a reversible displacement of tautomeric equilibrium. This unexpected phenomenon is inhibited by a very small modification of polarity. The photodegradation products were detected using liquid chromatography–mass spectrometer (LC/MS), to detect their molecular masses and thus obtain a broad idea of their identity. The incidence of photodegradation on the SPF value was measured. The studies of photoreactivity of the sun filters OMC and DBM has been published in an international journal. The in vitro transdermal penetration study of the UV filters and their breakdown products will be carried out on the skin of the pig’s ear installed on diffusion cell. The results show that the cutaneous absorption of the two filters is very low
8
Lemaitre-Aghazarian, Virginie. "Etude "in vitro" sur cellules de diffusion du passage transdermique et/ou transmembranaire des filtres solaires et rétinoi͏̈des." Aix-Marseille 2, 1996. http://www.theses.fr/1996AIX22534.
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Mohammedi, Mourad. "Etude de matériaux de garnissage en vue d'une réduction géométrique des filtres biologiques dans le cadre de l'assainissement autonome." Limoges, 1998. http://www.theses.fr/1998LIMO0024.
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L'objectif de ce travail est d'observer le comportement de materiaux filtrants tres differents vis-a-vis de criteres dont depend la qualite d'une epuration biologique. Les criteres retenus sont l'hydrodynamique du filtre insature, la capacite d'aeration des massifs, ainsi que leur aptitude a eliminer les matieres en suspension. Les materiaux les mieux adaptes pour une reduction geometrique des filtres biologiques utilises en assainissement autonome sont recherches. L'etude hydrodynamique des materiaux repose sur la determination de leur capacite de retention de l'eau et les temps de sejour moyens dans le filtre. Une methode systemique a ete developpee et permet de caracteriser la quantite totale d'eau mise en jeu dans un massif filtrant. La caracterisation des massifs suivant leur capacite d'aeration consiste a calculer les constantes de transfert propres a chacun des materiaux. Des modeles traduisant l'evolution des concentrations en oxygene dissous en fonction de la charge appliquee et de la hauteur du massif sont proposes. L'aptitude des massifs a eliminer (retention mecanique-hydrolyse) les matieres en suspension a ete etudiee en utilisant des particules synthetiques (amidon insoluble de pomme de terre). Une etude du mecanisme de capture est effectuee sur deux materiaux distincts (sable et sepiolite) et un modele de filtration en profondeur est applique. Il faut noter que les conditions operatoires retenues s'ecartent de celles rencontrees dans la litterature. Un modele general couplant la retention mecanique et la degradation biologique est propose et des simulations numeriques sont presentees. Ces calculs ont ete effectues en utilisant des constantes cinetiques d'hydrolyse des particules determinees experimentalement. Ces diverses etudes ont permis de selectionner la sepiolite et les deux zeolithes (clinomin et chabamin). L'epuration biologique d'un effluent septique menee sur ces materiaux revele d'excellents rendements epuratoires pour une charge de 5 cm. J#-#1. Une elevation de la charge hydraulique est pratiquee (25 cm. J#-#1) et montre que de bonnes performances epuratoires sont conservees, ce qui laisse presager qu'une reduction geometrique des filtres garnis de ces materiaux est possible.
10
Allegrini, Charles. "Etude par spectroscopie infrarouge à transformée de Fourier de l'adsorption de gaz sur filtres à charbon actif." Aix-Marseille 3, 1993. http://www.theses.fr/1993AIX30040.
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L'efficacite d'un systeme d'epuration d'air, deja existant et operant en milieu confine, a ete testee. Ce systeme qui utilise des filtres a charbon actif, doit fonctionner avec une vitesse de passage de l'air pollue particulierement elevee. Les polluants etudies sont co (1500 ppm), so2 (100 ppm), no2 (50 ppm) et hcl (500 ppm). Un nouvel appareillage capable de generer des atmospheres polluees de facon dynamique a ete mis au point et une methode quantitative basee sur la spectroscopie irtf est decrite. De nombreuses courbes de percee experimentales ont pu ainsi etre etablies en tenant compte de differents parametres comme la masse et la granulometrie du charbon actif et la section des filtres. Dans un second temps, nous avons modelise ces differentes courbes de percee. Cette modelisation nous a montre que le charbon actif n'etait pas sature dans les conditions d'analyse et nous a permis de determiner dans un temps relativement court, les equations generales de la cinetique d'adsorption des polluants et les quantites de polluants adsorbes (capacites d'adsorption). En resume, cette etude a permis d'optimiser le fonctionnement du systeme d'epuration d'air
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Potard, Gwénaëlle Marie-Pierre. "Etude de l'absorption et de la repartition cutanee de filtres solaires in vitro/in vivo, apres application topique sur peau humaine : approche par la methode des strippings (doctorat : pharmacologie experimentale et clinique)." Paris 11, 2000. http://www.theses.fr/2000PA114810.
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Liang, Yan. "Integrated Frequency-Selective Conduction Transmission-Line EMI Filter." Diss., Virginia Tech, 2008. http://hdl.handle.net/10919/26360.
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The multi-conductor lossy transmission-line model and finite element simulation tool are used to analyze the high-frequency attenuator and the DM transmission-line EMI filter. The insertion gain, transfer gain, current distribution, and input impedance of the filter under a nominal design are discussed. In order to apply the transmission-line EMI filter to power electronics systems, the performance of the filter under different dimensions, material properties, and source and load impedances must be known. The influences of twelve parameters of the DM transmission-line EMI filter on the cut-off frequency, the roll-off slope, and other characteristics of the insertion gain and transfer gain curves are investigated. The most influential parameters are identified. The current sharing between the copper and nickel conductors under different parameters are investigated. The performance of the transmission-line EMI filter under different source and load impedances is also explored.
The measurement setups of the DM transmission-line EMI filter using a network analyzer have been discussed. The network analyzer has a common-ground problem that influences the measured results of the high-frequency attenuator. However, the common-ground problem has a negligible influence on the measured results of the DM transmission-line EMI filter. The connectors and copper strips between the connectors and the filter introduce parasitic inductance to the measurement setup. Both simulated and measured results show that transfer gain curve is very sensitive to the parasitic inductance. However, the insertion gain curve is not sensitive to the parasitic inductance. There are two major methods to reduce the parasitic inductance of the measurement setup: using small connectors and applying a four-terminal measurement setup. The transfer gain curves of three measurement setups are compared: the two-terminal measurement setup with BNC connectors, the two-terminal measurement setup with Sub Miniature version B (SMB) connectors, and the four-terminal measurement setup with SMB connectors. The four-terminal measurement setup with SMB connectors is the most accurate one and is applied for all the transfer gain measurements in this dissertation.
This dissertation also focuses on exploring ways to improve the performance of the DM transmission-line EMI filter. Several improved structures of the DM transmission-line EMI filter are investigated. The filter structure without insulation layer can greatly reduce the thickness of the filter without changing its performance. The meander structure can increase the total length of the filter without taking up too much space and results in the cut-off frequency being shifted lower and achieving more attenuation. A prototype of the two-dielectric-layer filter structure is built and measured. The measurement result confirms that a multi-dielectric-layer structure is an effective way to achieve a lower cut-off frequency and more attenuation.
This dissertation proposes a broadband DM EMI filter combining the advantages of the discrete reflective LC EMI filter and the transmission-line EMI filter. Two DM absorptive transmission-line EMI filters take the place of the two DM capacitors in the discrete reflective LC EMI filter. The measured insertion gain of the prototype has a large roll-off slope at low frequencies and large attenuation at high frequencies. The dependence of the broadband DM EMI filter on source and load impedances is also investigated. Larger load (source) impedance gives more attenuation no matter it is resistive, inductive or capacitive. The broadband DM EMI filter always has more high-frequency attenuation than the discrete reflective LC EMI filter under different load (source) impedances.Ph. D.
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Dikinya, Oagile. "The effects of self-filtration on saturated hydraulic conductivity in sodic sandy soils /." Connect to this title, 2006. http://theses.library.uwa.edu.au/adt-WU2007.0051.
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Billoud, Guy. "Développement d'un filtre numérique adaptatif contrôlant les phénomènes de bouclage : application à l'absorption acoustique active." Lyon 1, 1988. http://www.theses.fr/1988LYO10182.
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Presentation de diverses methodes permettant de mettre en oeuvre un filtre numerique realisant automatiquement l'attenuation de bruits aleatoires tout en controlant efficacement le bouclage contre-source detecteur, et ce sans connaissance initiale du systeme acoustique traite
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Sobczak, Nadine. "Filtres solaires et leur passage transcutané : étude de l'influence d'un écran minéral, le dioxyde de titane, sur la pérméation de la benzophénone-4." Lille 2, 1996. http://www.theses.fr/1996LIL2P079.
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Civitarese, Jamil Kehdi Pereira. "We're Chained: an analysis of systemic risk in finance." reponame:Repositório Institucional do FGV, 2015. http://hdl.handle.net/10438/15117.
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This dissertation presents two papers on how to deal with simple systemic risk measures to assess portfolio risk characteristics. The first paper deals with the Granger-causation of systemic risk indicators based in correlation matrices in stock returns. Special focus is devoted to the Eigenvalue Entropy as some previous literature indicated strong re- sults, but not considering different macroeconomic scenarios; the Index Cohesion Force and the Absorption Ratio are also considered. Considering the S&P500, there is not ev- idence of Granger-causation from Eigenvalue Entropies and the Index Cohesion Force. The Absorption Ratio Granger-caused both the S&P500 and the VIX index, being the only simple measure that passed this test. The second paper develops this measure to capture the regimes underlying the American stock market. New indicators are built using filtering and random matrix theory. The returns of the S&P500 is modelled as a mixture of normal distributions. The activation of each normal distribution is governed by a Markov chain with the transition probabilities being a function of the indicators. The model shows that using a Herfindahl-Hirschman Index of the normalized eigenval- ues exhibits best fit to the returns from 1998-2013.
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Junior, Roberto Nasser. "Otimização das colunas de absorção da recuperação de acetona na produção de Filter Tow por meio de estudos fenomenológicos e análise estatística." Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/3/3137/tde-18122009-141222/.
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A absorção é a etapa determinante da recuperação de acetona no Filter Tow, por reduzir a emissão de acetona e trazer melhorias à economia. Por isso, ela constitui o objeto deste estudo, que inclui desde a revisão dos conceitos fenomenológicos, considerando a escolha do melhor modelo de equilíbrio líquido-vapor, passando pela execução dos balanços coerentes de massa e o estabelecimento da Fotografia da situação original, relatando um caso complexo de transposição de pratos para recheios. Contudo, a operação das colunas de absorção é influenciada por outras variáveis de caráter desconhecido, ruídos em relação à fenomenologia, o que se pretende avaliar, justificando-se desenvolver estudo para avaliar seus efeitos. Com o objetivo geral de otimizar absorção, uma análise estatística foi executada a partir do levantamento de dados operacionais, utilizando todas suas variáveis, sejam as fenomenológicas, como os ruídos, com o objetivo específico de obter modelos empíricos que complementem as simulações fenomenológicas, aumentando sua abrangência. Para a execução da análise estatística, os conjuntos de dados históricos foram levantados e validados pelos balanços coerentes de massa e pela Fotografia, o que tornou possível sua evolução, desde a seleção das variáveis, até estabelecer os modelos de regressão, com os quais pode-se obter um novo modo de controle, que estabiliza a operação, possibilitando a otimização. Em termos ambientais, a utilização destes modelos resulta em redução de até 15% das perdas de acetona para o ambiente, como também de consumo energético, com uma economia da ordem de 1 milhão de reais por ano, sem quaisquer custos adicionais.Absorption is the key step of the acetone recovery at Filter Tow production, for reducing the acetone emission and improving economics. For this reason it is the subject of this study, including the revision of phenomenological concepts, considering the choice of the best vapor liquid equilibrium model, passing by the improvement of coherent mass balances and establishing the Photography of the original situation, detailing a complex case of transposition of sieve trays to structured packing. However, the operation of the absorption columns is influenced by other variables, with unknown impacts, noises in relation to the phenomenology, justifying the development of this study, for evaluating them. With the general objective of optimizing the absorption, a statistical analysis is performed from collecting operating data, considering all variables, phenomenological and noises, with the specific objective of getting empirical models complementing the phenomenological simulations, increasing their comprising. For performing the statistical analysis sets of historical data have been collected and validated by coherent mass balances and the Photography, making possible its evolution, from the selection of the variables till establishing the regression models, and with them getting a new control way, which stabilizes the operation, allowing the optimization. In environmental terms, the use of these models results in up to 15% decrease in acetone losses to the environment, as well as power consumption with a saving of approximately 1 million reais per year, without any additional costs.
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Bodi, Geoffroy. "Débruitage, déconvolution et extraction de caractéristiques de signaux dans le domaine temporel pour imagerie biomédicale optique." Mémoire, Université de Sherbrooke, 2010. http://savoirs.usherbrooke.ca/handle/11143/1588.
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Un scanner permettant l'imagerie moléculaire est d'un grand intérêt pour l'industrie pharmaceutique dans le développement de nouveaux médicaments, notamment pour visualiser leur efficacité m-vivo (par exemple pour le cancer). Le groupe de recherche TomOptUS développe un scanner par tomographie optique diffuse par fluorescence pour imagerie moléculaire sur petit animal. Le but est de localiser en 3D les centres de fluorescence d'un traceur injecté dans l'animal. À cette fin, nous utilisons des mesures de signaux optiques de fluorescence obtenues par comptage de photons corrélé en temps (mesures dans le domaine temporel). On sait que les mesures contiennent de l'information sur les caractéristiques optiques du milieu, mais à ce jour, cette information n'est pas exploitée à son plein potentiel. Extraire cette information est essentiel en reconstruction tomographique. Le système d'instrumentation, comme tout système de mesure, celle-ci influe sur le signal optique à mesurer. Mathématiquement, les mesures optiques dans un milieu peuvent être décrites comme la convolution entre le signal d'intérêt et la fonction de réponse (ou fonction de transfert) du système de mesures optiques (IRF - instrument response function), le tout perturbé par du bruit. Les causes du bruit proviennent du système de détection, des conditions d'utilisation du système et des facteurs extérieurs. Il est indispensable d'éliminer les différents effets perturbateurs pour permettre l'extraction de caractéristiques de ces signaux. Ces caractéristiques dépendent des paramètres optiques du milieu diffusant. On distingue deux propriétés physiques, le coefficient d'absorption µ[indice inférieur a] et le coefficient de diffusion réduit µ'[indice inférieur s]. Un premier objectif du projet est de débruiter les mesures. À cette fin, un algorithme de débruitage par les ondelettes a été développé. Un second objectif est de concevoir un algorithme de déconvolution pour éliminer l'influence de l'IRF. La déconvolution est le raisonnement inverse de la convolution. Une solution est l'utilisation du filtre optimal de Wiener. Une fois cela réalisé, un troisième objectif consistait à implémenter un algorithme de régression non linéaire pour extraire les caractérisitiques optiques du milieu des courbes temporelles afin de caractériser le milieu. Pour cela, un modèle analytique de propagation de la lumière, le modèle développé par Patterson, Chance et Wilson, est comparé à nos mesures traitées. Par minimisation de l'erreur quadratique moyenne, il est ainsi possible de déterminer la valeur des paramètres optiques recherchés. Pour qualifier au mieux la méthode de déconvolution, la convolution itérative (IC- Itérative Convolution) ou reconvolution a également été implémentée. Actuellement, la reconvolution est la méthode la plus couramment utilisée en imagerie optique pour caractériser un milieu. Elle consiste à convoluer le modèle avec l'IRF du système pour obtenir un modèle représentatif des mesures optiques du système d'instrumentation. Enfin, un quatrième objectif consiste à étudier, à l'aide du même modèle, des changements du comportement du signal, lorsqu'on fait varier les paramètres µ[indice inférieur a], µ'[indice inférieur s]. Ceci permettra d'acquérir de nouvelles connaissances sur les vitesses de propagation dans le milieu et sur les temps d'arrivée des premiers photons.
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Mhaouech, Imed. "Étude du transport de charges dans le niobate de lithium massif et réalisation de fonctions électro-optiques dans le niobate de lithium périodiquement polarisé." Thesis, Université de Lorraine, 2017. http://www.theses.fr/2017LORR0032/document.
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Le premier volet de cette thèse est consacré à la modélisation des phénomènes de transport dans le LN. Partant d'une analyse critique des modèles de bande usuels, nous montrons leur inadéquation dans le cas du LN et nous proposons un modèle de saut basé sur la théorie des petits polarons. Nous étudions d'abord par simulation Monte-Carlo la décroissance d'une population de polarons liés NbLi4+ relaxant vers des pièges profonds FeLi3+. Nous montrons que les pièges FeLi3+ ont des rayons effectifs particulièrement grands, rayons qui augmentent encore à température décroissante, et limitent considérablement les longueurs de diffusion des polarons. Les résultats de simulations sont ensuite confrontés aux résultats expérimentaux obtenus par différentes techniques ; Absorption photo-induite, Raman, Enregistrement holographique et Pompe-sonde. Le deuxième volet de cette thèse est consacré aux applications électro-optiques dans le LN périodiquement polarisé (PPLN). Sous l’effet d’une tension électrique, l’indice de réfraction du PPLN est périodiquement diminué et augmenté, formant ainsi un réseau d’indice activable électriquement. Un premier composant utilisant l’effet électro-optique dans du PPLN a été développé et démontré expérimentalement. Dans ce composant, la lumière est défléchie sous l’effet de la tension électrique par le réseau d’indice. Ce déflecteur de Bragg atteint une efficacité de diffraction proche de 100% avec une faible tension de commande de l’ordre de 5 V. Un deuxième composant a également été proposé, où la lumière se propage perpendiculairement aux parois de domaines du PPLN. Dans cette configuration un réflecteur de Bragg électro-optique peut être réaliséThe first part of this thesis is devoted to the modeling of transport phenomena in the LN. From a critical analysis of the usual band models, we show their inadequacy in the case of LN and we propose a hopping model based on the theory of small polarons. We first study by Monte-Carlo simulation the population decay of bound polarons NbLi4+ in deep traps FeLi3+. We show that the traps (FeLi3+) have particularly large effective radii, which increase further at decreasing temperature, and considerably limit the diffusion lengths of the polarons. The results of simulations are then compared with experimental results obtained by different techniques; Light-induced absorption, Raman, Holographic storage and Pump-Probe. The second part of this thesis is devoted to electro-optical applications in the periodically poled LN (PPLN). Under the effect of an electrical voltage, the refractive index of the PPLN is periodically decreased and increased, thus forming an electrically activatable index grating. A first component using the electro-optical effect in PPLN has been developed and demonstrated experimentally. In this component, the light is deflected under the effect of the electrical voltage by the index grating. This Bragg deflector achieves a diffraction efficiency of close to 100% with a low drive voltage of the order of 5 V. A second component has also been proposed, where light propagates perpendicularly to the domain walls of the PPLN. In this configuration an electro-optic Bragg reflector can be realized
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Luzin, Rangel Magalhães. "Síntese e avaliação de novos candidatos a fotoprotetores absorvedores de radiações UVA e UVB, desenhados a partir de compostos análogos a produtos naturais." Universidade Federal de Goiás, 2018. http://repositorio.bc.ufg.br/tede/handle/tede/8893.
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It is known that sun exposure is one of the factors that contribute greatly to the appearance of skin cancer. Cancer cases have arisen annually on the planet and many of these cases have direct correlation with sun exposure. Knowing that both UVA and UVB radiation are harmful to health when the person is overexposed, the need arises for the use of devices to protect the skin and one of these ways and already recognized by the scientific community is through the prophylactic use of protectors solar power. Thus, this work proposes the synthesis, structural characterization, thermal stability verification, molar absorptivity calculation and in vitro UVB protection factor (PFUVB) calculated by the spectrophotometric method described by Mansur of new compounds derived from structures analogous to natural products. The structural planning was based on triazine derivatives (they are already commercially used with relative efficiency) and the use of chalcones, which are structures that besides having double bonds and conjugated aromatic structures that favor the absorption of the ultraviolet radiation, are studied compounds for various purposes and present in various plants, thus constituting a natural structure. In the planning, the choice of such structures was also due to the synthesis of compounds of high molar mass (above 900 daltons), contributing to safe structures, with low toxicity probability, low skin permeation and in compliance with the demands of the current legislation. The data obtained in the work reinforce the success of the same, where we had for the prototypes synthesized, molar absorptions superior to commercial filters. Establishing aresearch with the use of chalcones in safe and efficient sunscreens.
É sabido que a exposição solar é um dos fatores de grande contribuição para o surgimento do câncer. Casos de câncer tem surgido anualmente no planeta e muitos desses casos tem direta correlação com a exposição solar. Sabendo que tanto a radiação UVA quanto a UVB são nocivas à saúde quando o indivíduo é exposto em demasia, surge a necessidade do uso de artifícios para a proteção da pele e uma dessas maneiras e já reconhecida pelo meio científico é através do uso profilático de protetores solares. Assim este trabalho se propôs a síntese, caracterização estrutural, verificação de estabilidade térmica, cálculo de absortividade molar e fator de proteção solar UVB (FPUVB) in vitro calculado pelo método espectrofotométrico descrito por Mansur de novos compostos derivados de estruturas análogas a produtos naturais. O planejamento estrutural foi baseado nos derivados triazínicos (pois já são de uso comercial com relativa eficiência) e o uso de chalconas, que são estruturas que além de possuir duplas ligações e estruturas aromáticas conjugadas que favorecem a absorção da radiação ultravioleta, são compostos bastante estudados para diversos fins e presente em vários vegetais, constituindo assim uma estrutura natural. No planejamento, a escolha de tais estruturas se deu também pela síntese de compostos de alta massa molar (acima de 900 Daltons), contribuindo para estruturas seguras, com probabilidade de baixa toxicidade, baixa permeação cutânea e atendendo aos reclames das legislações vigentes. Os dados obtidos no trabalho reforçam o sucesso do mesmo, onde tivemos para os protótipos sintetizados, absorções molares superiores a filtros comerciais. Estabelecendo assim uma nova linha de pesquisas com a utilização de chalconas em filtros solares seguros e eficientes.
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Couture, Pierre. "Galaxies à sursauts de formation stellaire : Simulations pour la mission UVIT." Thesis, Université Laval, 2011. http://www.theses.ulaval.ca/2011/28432/28432.pdf.
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Dikinya, Oagile. "The effects of self-filtration on saturated hydraulic conductivity in sodic sandy soils." University of Western Australia. School of Earth and Geographical Sciences, 2007. http://theses.library.uwa.edu.au/adt-WU2007.0051.
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[Truncated abstract] Self-filtration is here defined as particle detachment and re-deposition causing re-arrangement of the particles and therefore pore space which affects water flow in soil by decreasing hydraulic conductivity. This is of particular important in soils which are susceptible to structural breakdown. The objective of this thesis was to examine the dynamics of the self-filtration process in sodic sandy soils as affected by ionic strength and soil solution composition. The temporal changes of hydraulic conductivity and the elution of fine particles from soil columns were used as the main criteria to assess selffiltration. Two porous media exhibiting significantly different structural cohesion were examined, one a loamy sand (Balkuling soil) from agricultural land use and the second a mining residue from mineral sands operations . . . The effects of the composition of mixed calcium (Ca) and sodium (Na) ions in solution (sodium adsorption ratio (SAR)) on the exchange behaviour and saturated hydraulic conductivity were examined by carrying out batch binary exchange and saturated column transport experiments. A strong preference for Ca2+ ions in the exchange complex was observed for both soils. Generally K/Ko was found to decrease with increasing sodium adsorption ratio with the more structured Balkuling soil maintaining K/Ko for SARs 3 and 5 at an electrolyte concentration of 100 mmol/L. However measurements at the critical threshold and turbidity concentrations at a SAR of 15 revealed structural breakdown of the pore matrix system attributed to various extents of slaking, swelling, dispersion and decreases of pore radii as a result of selffiltration during leaching. These experiments illustrate the wide range of complex interactions involving clay mineralogy, solution composition and structural factors which can influence the extent of mobilization, transport and re-deposition of colloidal particles during the leaching process in soil profiles.
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Maalouf, Azar. "Contribution à l'étude des procédés de réalisation de circuits intégrés optiques en matériaux polymères." Phd thesis, Université Rennes 1, 2007. http://tel.archives-ouvertes.fr/tel-00456179.
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Au laboratoire, cette thèse fait suite à des modélisations sur des fonctions passives intégrées optiques à base de micro-résonateurs en anneaux. Pour les réaliser, une étude de toutes les étapes de réalisation de circuits en polymère a été effectuée. Les objectifs sont l'obtention de guides arêtes, ridge monomodes avec des performances acceptables et la miniaturisation de fonctions avec les matériaux et technologies envisageables au CCLO. Des points bloquants ont été identifiés au départ, tels que le manque d'adhérence entre matériaux, les incompatibilités technologiques et optiques entre polymères, les phénomènes liés au procédé occasionnant des pertes optiques excessives. Après un état de l'art sur les polymères pour guides d'ondes optiques, le manuscrit présente les travaux spécifiques sur le choix des matériaux et l'évaluation de l'adhérence de polymères amorphes sur les substrats envisagés, ainsi que la qualité et la reproductibilité des dépôts et leur gravure sèche par plasma. L'analyse de l'apparition de défauts de surface des films et " ridge " ainsi que les solutions trouvées pour les éliminer, sont plus particulièrement développés. L'adaptation de la photolithographie classique en UV proche est détaillée pour atteindre des tailles de motifs submicroniques. Les résultats des méthodes d'analyse entreprises pour discriminer les différents facteurs de pertes optiques en propagation sont discutés. Enfin, les réalisations de guides monomodes à base de polymères méthacryliques pour le coeur ainsi que les premières structures de filtres et multiplexeurs en micro-résonateurs intégrés en anneaux et à faible intervalle spectral libre (1-3nm) sont présentées et analysées.
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Lintis, Laura. "Étude des phénomènes de sorption de l’eau sur des aérosols solides émis lors d’un incendie : identification des paramètres physico-chimiques d’influence." Thesis, Université de Lorraine, 2018. http://www.theses.fr/2018LORR0304/document.
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Au cours d’un incendie dans une installation nucléaire de base (INB), les filtres à très haute efficacité (THE) sont colmatés par un dépôt (ou « gâteau ») de suies (des agrégats de nanoparticules carbonées). L’effet de l’humidité, observée au niveau du gâteau de suies par la présence d’un condensat, n’est pas encore pris en compte dans les modèles de colmatage développés dans la communauté scientifique. Dans ce contexte, la présente étude vise à mieux comprendre le phénomène de sorption de l’eau sur les suies. Pour ce faire, des suies dites « analytiques » ont été produites avec différents combustibles isolés, ceci à différentes teneurs en dioxygène, et des suies « d’incendie » ont été produites à partir d’essais de feux à grande échelle, ceci à différentes ventilations et avec des combustibles réalistes (boîte à gants, câbles électriques, huile hydraulique). Les propriétés physico-chimiques de ces suies (morphologie, porosité, surface spécifique, composition chimique et élémentaire) ont été déterminées parallèlement à l’obtention des isothermes de sorption d’eau, pour des suies sous forme de pastilles et de poudres non tassées. Les paramètres obtenus avec le modèle Dubinin-Serpinski pour une première catégorie de suies hydrophobes ont permis de proposer une modélisation pertinente des isothermes caractéristiques des suies analytiques. Par ailleurs, les isothermes de sorption de l’eau sur des gâteaux de suies dites hydrophiles et essentiellement issues de combustibles et situations réelles d’incendie, ont été modélisées à l’aide de l’équation de D’Arcy et Watt (DW). Pour cette seconde catégorie de suies, les paramètres du modèle DW apparaissent relativement dispersés, comparés à ceux obtenus pour les suies analytiques. Cette relative dispersion s’explique par des propriétés très variables des suies d’incendie et notamment par la présence importante d’oxygène et d’halogènes (chlore, phosphore). Cette étude a donc permis de mettre en évidence une adsorption plus importante pour les suies d’incendie, conduisant à la condensation capillaire, cette dernière étant favorisée pour les suies sous forme de pastilles. In-fine, la composition chimique et élémentaire des suies apparaît ainsi comme le paramètre prépondérant du phénomène de sorption de l’eau sur les suiesDuring a fire in a nuclear plan, the high efficiency particle air (HEPA) filters are clogged by a deposit (or “cake”) of soot, the latter corresponding to carbonaceous nanoparticles aggregates. The effect of humidity, observed on the filters by the presence of condensed water, is still not considered in the clogging models developed in scientific community. In this context, the aim of this study consists on a better understanding of the water sorption on the soot. The experimental approach was first the production of “analytical” soot with different isolated fuels and at different dioxygen concentrations, and of “fire” soot at large scale with different ventilations and complex elements (glove boxes, electrical cables, hydraulic oil). The physicochemical properties (morphology, porosity, specific surface area, elemental and chemical composition) and the water sorption isotherms, for samples at compacted pellet and powder state, have been determined. The parameters from the model of Dubinin-Serpinski, obtained for a first class of hydrophobic soot, enabled to propose a relevant model, characteristic of the analytical soot. Furthermore, water sorption isotherms on soot cake, coming from realistic fires and fuels, have been modeled with the D’Arcy and Watt (DW) equation. For this second class of hydrophilic soot, the DW parameters appear relatively more dispersed. This relative dispersion is due to the different properties of the fire soot and especially to the presence of high amounts of oxygen and halogens (chlorine, phosphor). This study enabled to highlight a more significant water adsorption on fire soot, leading to the capillary condensation, which is favored for soot compacted into pellet. Soot chemical a and elemental composition appeared to be the most influencing parameter on water sorption phenomenon
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Vuong, François. "Modélisation du comportement des cartouches de protection respiratoire : exposition à des atmosphères complexes de vapeurs organiques et effet des cycles d’utilisation." Thesis, Université de Lorraine, 2016. http://www.theses.fr/2016LORR0255/document.
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Les vapeurs de composés organiques volatils (COV) représentent un risque chimique pour les travailleurs. Les cartouches de protection respiratoires sont un moyen efficace contre les expositions à ces vapeurs. L’objectif de cette thèse est la modélisation de l’exposition des cartouches dans les situations complexes : présence d'un mélange de vapeurs et cycle d’utilisation, à partir d’une étude expérimentale basée sur l’adsorption dynamique sur colonne. Suite à la contribution de R. Chauveau (thèse UL – 24/11/2014) la présente thèse poursuit l’étude sur la modélisation de l’adsorption des mélanges de vapeurs. Des expositions à des mélanges de COV et une étude cinétique par la méthode chromatographique perturbative ont été effectuées. Le deuxième volet est consacré à la modélisation d’un cycle d’utilisation en 3 étapes (exposition - stockage – réutilisation), pour 6 COV : acétone, acétonitrile, 2-butanone, cyclohexane, dichlorométhane et éthanol. Les temps de claquage ont pu être prédits correctement pour les mélanges acétone/éthanol et cyclohexane/heptane. Une déviation est observée pour le mélange éthanol/cyclohexane car l’équilibre d’adsorption n’a pu être reproduit avec précision par les modèles et parce que la présence d’une covapeur influe grandement sur les cinétiques d’adsorption en mélange. Les travaux ont révélé des failles dans l’approche préventive consistant à assimiler une exposition de mélanges à une exposition à celle du composé le plus volatil en lui affectant la concentration totale du mélange. En ce qui concerne les risques liés à une réutilisation des cartouches, des percées immédiatement après réutilisation (IBUR) ont été observées expérimentalement. Ce comportement a pu être décrit par un modèle de diffusion statique. Le risque d’IBUR est élevé pour les COV diffusant rapidement : l’acétonitrile, l’acétone et le dichlorométhane. Une évaluation est proposée pour distinguer les propriétés du système qui influencent l’apparition de l’IBURVolatile organic compounds (VOC) represent a chemical risk for workers. Respiratory protective cartridges are effective equipment against vapours exposure. The objective of the present PhD thesis is the modelling of cartridge exposure in more complex situations: presence of vapours mixture and reuse cycle, from a dynamic adsorption experimental study in column bed. Further to the contribution of R. Chauveau (PhD thesis -24/11/2014), the present manuscript extends the study vapours mixtures adsorption on activated carbon. The second section is devoted to model a cycle use in 3 steps (exposure - storage – reuse), for 6 VOC: acetone, acetonitrile, 2-butanone, cyclohexane, dichloromethane and ethanol. VOC mixtures exposure and kinetic study by the method of perturbative chromatography have been carried out. The service life is correctly predicted for acetone/ethanol and cyclohexane/heptane mixtures. A deviation has been observed for ethanol/cyclohexane mixture because the adsorption equilibrium has not been accurately reproduced by model. These works have also pointed out inconsistency in the preventive approach which assimilates a mixture exposure to single vapour exposure by the most volatile compound at concentration the sum of that of all components of the mixture. Regarding the risks related to cartridge reuse, immediate breakthrough upon reuse (IBUR) has been experimentally recorded. This behaviour can be described by a static diffusion model. The mass transfer in the particle by surface diffusion is the main reason. The risk of IBUR is higher for fast diffusing VOC: acetonitrile, acetone and dichloromethane. An assessment is suggested in order to distinguish the properties of the system which can influence the occurrence of IBUR
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HAN-YUAN, CHANG, and 張瀚元. "Design of Tunable Absorptive Bandstop Filters." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/murywd.
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碩士國立中央大學
電機工程學系
107
This thesis presents two types of tunable absorptive bandstop filter (TABSF) design, with both a tunable center frequency and a high power dissipation. Specifically, multiple varactors and a resistor are added to the conventional reflective bandstop filter to achieve the proposed tunable absorptive bandstop filter designs. The capacitance of the varator can be controlled by the bias voltage to change the equivalent electrical length and thus the resonance frequency of the transmission line resonators. Therefore, the stopband center frequency becomes tunable. In addition, the resistor provides the proper absorption of the input signal, which turns the reflective bandstop filter into an absorptive one. Two designs are proposed for narrowband or wideband applications. To validate the proposed design methods, test circuits implemented on a printed circuit board are realized, too. For the proposed narrowband tunable absorptive bandstop filter design, the frequency tuning range is 1.95~3.29 GHz (69% tenability). The stopband rejection level is around 7.621~18.633 dB and the 3-dB rejection bandwidth is around 7.7~5.2%.The corresponding power dissipation at the stopband center frequency is around 82.687~98.335%.Next, a dual-band tunable absorptive bandstop filter is realized by the cascade of two proposed narrowband tunable absorptive bandstop filters. The frequency tuning range for the first and second stopbands are 2.41~3.88 GHz (61% tunability) and 3.30~4.89 GHz (39% tunability) respectively. The stopband rejection level is 6.759~16.785 dB for the first stopband while it is 6.075~15.010 dB for the second stopband. The 3-dB rejection bandwidths are 7.5~5.7% and 6.7~5.7% respectively while the power dissipation is 78.790~98.335% and 73.494~95.965% respectively for the first and second stopbands. Finally, the stopband center frequency of the proposed wideband tunable absorptive bandstop filter can be tuned from 520 to 710 MHz (37% tunability). The stopband rejection level is around 63.893~89.003 dB and the 30-dB rejection bandwidth is 23.9~22.1%. The bandwidth for larger than 90% power dissipation is around 35.9~13.5%. The proposed tunable absorptive bandstop filters feature a simple design flow and a high design flexibility. They can be easily designed with the desired stopband center frequency, stopband bandwidth and filter order to meet the system specifications.
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Chien, Shih-Huan, and 簡世桓. "Wideband Absorptive Bandstop Filters with Good Selectivity." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/w53h98.
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碩士國立中央大學
電機工程學系
105
This study presents a new type of wideband absorptive bandstop filter (ABSF) design whose stopband bandwidth is several times wider than those in the other related previous works. In addition, high frequency selectivity and good passband response are achieved. The proposed wideband ABSF is based on adding one additional resistor to a conventional wideband bandstop filter to absorb the input power. A complete design procedure is proposed to realize the circuit design under given specifications. To validate the proposed design method, a proposed wideband ABSF with a center frequency of 2 GHz, a fractional bandwidth (FBW) of 50% and a Chebyshev response with a ripple constant ɛ = 0.1005 is implemented on a printed circuit board. The measured stopband rejection is 60.7 dB at 2 GHz. The measured 30-dB rejection bandwidth is 23.5% and the shape factor, i.e., RBW3-dB /RBW30-dB is 2.1. The measured bandwidth for better than 95% power dissipation is 35.6%. In addition, the measured input reflection coefficient is better than 11.2 dB from dc to 8 GHz and good stopband performance is achieved. This study also presents two modified design methods for expanding the realizable range on stopband bandwidth and filter order of the proposed wideband ABSF. Wideband ABSFs with FBWs ranging from 30% to 70% are implemented, and the corresponding measured 30-dB rejection band-width ranges from 11.9% to 42%. The measured input return losses are all better than 10 dB. Larger than 90% of the input power within the stopband can be successfully dissi-pated. The proposed ABSF features a complete design procedure with high design flexi-bility. The stopband bandwidth and frequency selectivity can all be designed according to the desired specifications. They can be applied to the harmonic suppression of nonlinear active devices to improve the system performance.
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Hsu, Yu-Hsiang, and 許淯翔. "Absorptive Bandstop Filters Based on Mushroom-Type Electromagnetic Bandgap Structures." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/k7tndd.
Full textAbstract:
碩士國立臺灣大學
光電工程學研究所
106
Due to the rapid development of wireless communications in recent years, communication technologies have become more and more developed and diversified. The requirements for transmission speeds are getting faster and faster, and different communication systems need to be integrated. Therefore, problems that will not occur or have little impact in the past have arisen. As the development of communications has gradually interfered with the performance of components or systems as a whole, the requirements for filters have become more and more stringent. This is different from conventional reflective filters. Absorbing filters have received increasing attention in recent years. This research proposes a new prototype of the absorptive filter circuit, and according to different designs can obtain narrowband and broadband absorptive filter effects. Then, a mushroom-type electromagnetic bandgap structure, resistors and microstrip are used to implement an absorptive filter, and an equivalent circuit model and design flow are proposed. Finally, the experimental results also showed the effects of broadband absorption filters as expected. Although there were some slight differences, the overall trend was consistent, confirming the accuracy and reliability of our circuit model and design flow. In addition, through the comparison of experiments and simulations, the main factors affecting the performance of components are found out in the measurement and process errors.
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(5930435), Wei Yang. "Tunable Absorptive Bandstop-to-All-Pass Filter Synthesis, Control, Applications, and Optimizations." Thesis, 2019.
Find full textAbstract:
In this dissertation, the synthesis of the triplet absorptive topology is presented in detail. The coupling matrix of this topology is derived. The synthesis theory extends to arbitrary phase of the transmission line used in the topology. A new FSL that yields the state-of-the-art performance is proposed. It employs the triplet absorptive filter topology, which enables absorptive response in a wider tuning range, to achieve high isolation (70 dB) everywhere in its octave tuning range. This was not possible with any existing FSLs. This triplet filter topology also gives bandstop-to-all-pass response, which enables controlled attenuation, or variable-attenuation control. The filter is implemented in high-Q evanescent-mode cavity technology, which yields low insertion loss in all-pass response. The proposed FSL is integrated with feedback control loops to enable in-field operations. For one step further, the FSL system is redesigned for optimization of robustness and reliability without compromising the state-of-the-art RF performance.
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Shao, Jhih-Ying, and 邵致穎. "The Design of Absorptive Bandstop Filter." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/xj3xuq.
Full textAbstract:
碩士國立中央大學
電機工程學系
102
In this study, in order to cooperate with the development of ALMA (Atacama Large Milli- meter/Submillimeter Array) Band-1 receiver front-end, novel absorptive bandstop filter (ABSF) implemented using GaAs semiconductor process is proposed. The proposed ABSF can help minimize the impact of LO-to-RF leakage on the conversion loss degradation of mixer in the ALMA Band-1 receiver. First, novel design method of ABSF is proposed and a complete design procedure and formulae are established. The proposed ABSF structure is based on introducing resistor to the bandstop resonator appropriately so as to dissipate the reflected signals in the stopband. The design of a 3rd-order ABSF is presented to demonstrate the achieved performance, and it is used for verifying the proposed design formulas. The ABSF is designed with a fractional bandwidth of 5% and a center frequency of 2 GHz. The measured return loss is better than 17.92 dB in the passband. The measured rejection at stopband center frequency is 34.83 dB, and the maximum stopband power dissipation is 99.8%. Second, the Q-Band ABSF for ALMA Band-1 receiver application is proposed. The stopband frequency is from 31 to 33 GHz, which corresponds to a stopband fractional bandwidth of about 7%. The passband frequency is from 35 to 52 GHz. The ABSF is implemented in GaAs using the WIN 0.15 um pHEMT process, and the chip size is 2.5 mm×2 mm. In the measured results, more than 93.4% of the power within the stopband can be dissipated by the proposed ABSF, and the rejection at the stopband center frequency is 35.6 dB. The insertion loss is better than 2.44 dB and the return loss is better than 15.23 dB in the passband. To facilitate the receiver system integration, the proposed ABSF is then integrated with the bandpass filter on the same chip. Compared with other related previous works, the proposed ABSF features a complete and simple design procedure with better design flexibility. The stopband bandwidth, filter selectivity and passband ripple can all be designed according to the specifications. The proposed ABSF is easy to realize such that it is helpful for applications in front-end receiver designs.
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WU, CHENG-HAN, and 吳承翰. "Design of Wideband Bandstop Filter with High-selectivity and Wideband Absorptive Bandstop Filter." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/x3pb9v.
Full textAbstract:
碩士國立中正大學
電機工程研究所
105
For modern wireless communication applications, the researches of filter play an important role since it can have an effect on the sensitivity of communications systems. In this thesis, two parts are presented. The first part is the wideband bandstop filter with high-selectivity at chapter 3. To achieve wideband and high-selectivity performance, a structure of the planar bandstop filter (BSF) with four sections which can control transmission zeros (TZs) to adjust the bandwidth of requiring stop band is presented. We employ two methods to produce the TZs, respectively coupling lines with L-resonators and through lines with open-circuit stubs. The S-parameter decay deeply and quick when the insertion loss next to stop band. And the presented type can replace the conventional type with a quarter wavelength open-ended transmission line resonator. by combine with L-shaped resonators. The second part is the absorptive bandstop filter with wideband performance at chapter 4. The initial design comes from 4-th order reflective BSF, and adds lump elements (resistance) to produce absorptive effect. Use formulas to calculate the impedance match for absorptive part. For improving narrow bandwidth performance, I utilize π-shaped resonators. Finally, two of researches get good performance with simulations.
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Chou, Ton Lian, and 周棟樑. "Absorption and Scattering of Beta Particles in Filters." Thesis, 1996. http://ndltd.ncl.edu.tw/handle/83712170283650877507.
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MAO, TZU-CHI, and 毛子奇. "Thin Film Interference Filter and Absorption Filter Used for Enhancing Night Vision Acuity." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/eba34b.
Full textAbstract:
碩士逢甲大學
視光科技碩士在職學位學程
106
The purpose of this research is to study people’s vision under night-time conditions, using thin-film filter and absorption filter to improve night vision ability. The proposed method is to use thin-film coating technology to increase optical visibility, through thin film interference filters to make visual images clearly on the target imaging of the retina and to increase the visual sensitivity. The absorption filter is the most widely utilized type of filter, and operated by attenuation of light through absorption of specific wavelengths, so that other wavelengths of light pass through the filter to reduce glare and to enhance contrast sensitivity of seeing a target, thus it can improve the visual acuity. Characteristics of combining two types of filters can enhance the visual acuity at night time. This research carries out the experimental analysis for two kinds of filters, and the combination of the two filters can help to promote higher night vision sensitivity. Using the advantages of both filters could reduce the degree of eye fatigue and provide a good protection for the personal security.
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Nogueira, Felipe Guimaraes. "Development of an infrared absorption spectroscope based on linear variable filters." 2006. http://hdl.handle.net/1969.1/ETD-TAMU-1075.
Full textAbstract:
The objective of this thesis is to develop a low-cost infrared absorption spectroscope
based on linear variable filter (LVF) technology for the automated detection of gases and
vapors, and the semi-automated detection of liquids. This instrument represents an
alternative to electronic-nose instruments based on cross-selective gas sensor arrays.
Instead, the proposed instrument uses the idea of computational “pseudo-sensors”,
whereby spectral lines in an analytical instrument are clustered into groups and used as
independent variables. We characterize the system on a number of performance metrics,
uncovering its detection limits and resolving power. We present calibration methods to
estimate the concentration of analytes in a matrix of absorbing species, as well as signal
processing techniques for spectral classification. Specifically, we validate the instrument
on a mixture calibration problem with simple and complex chemicals, and compare the
efficiency of different calibration methods to estimate the concentration of one analyte in
the matrix. Moreover, we demonstrate the use of the instrument on two real-world
applications in the foodstuffs domain: oil adulteration and trans fatty acid (TFA)
detection. The instrument, combined with signal processing techniques, is able to fully discriminate oils, as well as classify margarine and spreads onto high-TFA and low-TFA
groups. Despite operating at a low spectral resolution, our results show that the LVF
based spectroscope is a promising alternative to traditional analytical techniques for
selected niche applications.
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CHIANG, ZONG-ZHE, and 江宗哲. "Research on Spectral Transmittance of IR Absorption Filter Annealing Process." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/ambhsw.
Full textAbstract:
碩士臺北城市科技大學
機電整合研究所
107
This paper focuses on an optical glass that absorbs infrared light by the material itself. This infrared absorbent filter is made of chemical formula mixed into powder, and then manufactured by high temperature melting, annealing process, precision processing and other procedures, wherein the main impact on spectral penetration values is in the formulation composition. However, in this optical glass material on the sensitive nature of temperature, different annealing process will also cause the impact on spectral penetration rate, the extent of which is worth exploring in depth. The study spindle is planned into two parts of the experimental stage, the first part for the glass test film production, in order not to change the chemical composition of the glass itself, with high temperature melting manufacturing procedures, only the annealing process to do temperature, time changes to do group production. The second part will be the test film with spectrometer individual measurement, and then explore the analysis of the spectral penetration rate of the numerical change severity. The experimental results show that: the temperature increase, will cause the maximum penetration significantly decreased, infrared light penetration will increase slightly. Lower temperatures can cause a significant increase in maximum penetration.
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CHENG, YU-HAO, and 鄭又豪. "Broadband CM Suppression and Dual-band Absorption E-type Common Mode Suppression Filter." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/hc3btf.
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Li, Chien-Te, and 李建德. "High Reliability Process of 8 inch Infrared Ray Absorption Type of Filter and Its Market Analysis." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/rbe28m.
Full textAbstract:
碩士國立臺北科技大學
機電整合研究所
95
The aim of this research is to study the technology of photoelectric component, the high reliability process of 8 inch infrared ray absorption type of filter, and its market analysis. Filter is the key component of various optical systems. In general, color filter is fabricated by coating method. This study presents the novel method for filter fabrication by high temperature sintering of Si, B, Al2O3, and other materials. Compared with conventional filter, the absorption type of filter have more stable spectrum because of its properties of invisible light absorption. This filter is promising to be a key component of high performance optical system for lighter, thinner, shorter, and smaller structure. The research and fabrication techniques of filter materials have been controlled by Germany and Japan industry. For development of new products, the survey of market, feasibility study on related resources, and forecast of new generation market are need to be carried out. The aim of this study for obtaining the most benefit from photoelectric market is on the basis of reviewing the related techniques, theory of commerce, innovated thought.
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Jim, Gibson. "Determination of inorganic components in coal using continuum source atomic and molecular absorption spectrometry with a filter furnace atomiser." Thesis, 2011. http://encore.tut.ac.za/iii/cpro/DigitalItemViewPage.external?sp=1000432.
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D. Tech. Chemistry.Suggests an alternative methodology based on slurry sampling in the FF atomiser (Katskov, 2007) and simultaneous multi-element electrothermal (SMET) AAS determination using a low resolution CCD spectrometer linked to a continuum light source (Katskov and Khanye, 2010).
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Molope, Itumeleng. "The determination of inorganic arsenic species in soil by an electrothermal atomic absorption spectrometer equipped with a filter furnace." 2010. http://encore.tut.ac.za/iii/cpro/DigitalItemViewPage.external?sp=1000201.
Full textAbstract:
M. Tech. Chemistry.Aims to develop of a method for the leaching of the total inorganic arsenic species [As(III) + aS(v)] from soil samples secondly a comparison of the analytical performance of the commercial Transverse Heated Graphite Atomizer (THGA) with the Transverse Heated Filter Atomizer (THFA) for arsenic determination and thirdly the application of the method developed for the determination of arsenic species in soil samples which have been collected in the vicinity of a gold mine