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Compact Trench Based Bend and Splitter Devices for Silicon-on-Insulator Rib WaveguidesQian, Yusheng 13 March 2009 (has links) (PDF)
Bends and splitters are typically the fundamental limiting waveguide components in reducing the size of planar lightwave circuits (PLCs) based on waveguides that have a low core/clad refractive index contrast, such as silicon-on-insulator (SOI) rib waveguides. This dissertation presents a solution to this problem in the form of trench-based bends (TBBs) and trench-based splitters (TBSs). Emphasis is placed on experimental demonstration of these components and their integration into practical devices exhibiting significant size reduction. First, a compact and low loss silicon-on-insulator rib waveguide 90◦ TBB is demonstrated based on an etched vertical interface and total internal reflection (TIR) realized by a trench filled with SU8. The measured loss for TE polarization is 0.32 dB ± 0.02 dB/bend at a wavelength of 1.55 μm, which is the best reported in literature. Next, 90◦ TBSs are reported in which each splitter occupies an area of only 11 μm x 11 μm. These components require fabrication of trenches with a nearly 10:1 aspect ratio. A variety of single TBSs are fabricated having different trench widths. The relative amount of power directed into the transmission and reflection arms of the splitters is measured. The TBS reflection and transmission ratio agrees with three dimensional (3D) finite difference time domain (FDTD) predictions. An 82 nm wide trench filled with index matching fluid is experimentally shown to have a reflection/transmission splitting ratio of 49/51 at a wavelength of 1550 nm. To increase the fabrication yield of TBSs, the splitter angle is modified from 90◦ to 105◦, which permits the trench width to be increased to 116 nm for a 50/50 splitter using SU8 as the trench fill material. The fabrication and measurement of compact 105◦ TBBs and TBSs are reported followed by their integration into 1 x 4, 1 x 8, and 1 x 32 trench-based splitter networks (TBSNs). The measured total optical loss of the 1 x 32 TBSN is 9.15 dB. Its size is only 700 μm x 1600 μm for an output waveguide spacing of 50 μm. Finally, a compact SOI trench-based ring resonator (TBRR) composed of 90◦ TBBs, TBSs, and rib waveguides is demonstrated. A TBRR with a ring circumference of 50 μm occupies an area of 20 x 20 μm. The free spectral range (FSR) is as large as 14 nm. By changing the trench fill material from SU8 (n = 1.57) to index fluid (n = 1.733), the peak wavelength can be shifted ∼2 nm. Fabricated TBSNs and TBRRs demonstrate that large size reductions are possible for devices based on TBBs and TBSs. The net result is bend and splitter configurations with a size that is essentially independent of core/clad refractive index contrast. The approach developed in this dissertation is applicable to a wide range of waveguide material systems that have small core/clad refractive index contrast.
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Complex Filters As as a Cascade of of Buffered Gingell Structures: Design from from Band-Stop ConstraintsJohnston, Samuel Robert 01 June 2016 (has links) (PDF)
This thesis presents an active Complex Filter implementation that that creates a transfer function with with a single real pole and a complex zero. The two-input/two-output network developed in in this thesis responds differently based upon upon the relative phase difference of of the two inputs. If a negative ninety-degree phase difference occurs between the two inputs, the filter will exhibits a bandstop response. While a positive ninety-degree phase difference exhibits a bandpass response. This topology is relatesd to to Gingell’s RC-CR polyphase topology but because of of the use of of op-amps, can be cascadedd without without suffering loading effects. This thesis will focusfocuses primarily on on the bandstop response characteristics of of the filter. In a several stage cascade, each stage contributes a notch to broaden the attenuation bandWhen several sections are cascaded, multiple notches will be created from each stage that forms a broader attenuation band. Closed form design equations were were derived to to give expressions for for the “attenuation floor”. These equations can be used by a designer to predict the attenuation provided by by a cascaded system. The closed form expressions derived in in this thesis are used to implement an example five-stage topology that that operates from from 147 Hz to to 3.34 KHz. The thesis also investigates the robustness of of multi-stage cascades to to component variations. Monte Carlo analysis is used to determines the effects of of cascading the filter in in different orders, component tolerances, and a comparison to to an idealized polyphase RC-CR topology.
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Konceptframtagning av vedklyv för inomhusbruk / Concept generating of log splitter for indoor useAkgül, Hazal-Dilan January 2023 (has links)
Vi lever i en tid där tillgången till energi är en fråga som berör en stor del av jordens befolkning. Efterfrågan på förnybara bränslen ökar och fasta bränslen såsom exempelvis ved blir ett alltmer attraktivt alternativ vid uppvärmning av hushåll. För att framställa ved för detta ändamål är de mest användbara vedklyvarna idag stora och lämpade för utomhusmiljöer. De alternativ som är någorlunda kompakta och som skulle kunna användas i inomhusmiljöer är dock manuella konstruktioner som kräver precision och handkraft. Det gör dem mindre användarvänliga till den större massan och produkten lämpar sig mindre bra till användare som, av olika anledningar, inte är kapabla att använda muskelkraft för att klyva veden. Målet med detta examensarbete var att ta fram ett konceptförslag på en vedklyv för inomhusbruk som syftar till att förbättra möjligheterna för klyvning av ved inomhus. Marknadsanalys och litteraturstudier har använts som metod i syfte att landa i en kravspecifikation. Litteraturstudien gav information om nödvändig klyvkraft beroende på träslag och dimensioner. Arbetet resulterade i ett koncept som möjliggör klyvning av tändved med upptill fem ton klyvkraft. Konceptet består i sin helhet av en elektrisk saxdomkraft och en ställning med till hörande bottenplatta och en kilklyv. Vidare möjliggör designen av ställningen att klyvkilens höjd kan justeras. Dimensionering av konstruktionens delar är dels baserade på fraktkostnader hos USPS, dels på att rätt mekanismen skall fungera enligt önskemål. Vedklyven visualiseras som CAD-modell där val av material och färg grundar sig arbetets konceptdefinition och konceptgenereringsfas. / We live in a time where access to energy is an issue that affects a large part of the world's population. The demand for renewable fuels is increasing, and solid fuels such as wood are becoming an increasingly attractive alternative for heating households. To produce wood for this purpose, the most serviceable log splitters today are large and suitable for outdoor environments. However, the reasonably compact alternatives that could be used in indoor environments are manual constructions that require precision and hand strength. These factors make them less user-friendly to the larger mass, and the product is less suited to users who, for various reasons, cannot use muscle power to split the wood. The objective of this thesis was to develop a concept proposal for a wood splitter for indoor use that aims to improve the possibilities for splitting wood indoors. The project commenced with market analysis, and literature studies have been used as methods in order to determine the most essential requirements. The literature study provided information on the necessary splitting force depending on the wood species and dimensions. The project result is a concept that enables firewood splitting with up to five tonnes of splitting force. The concept consists entirely of an electric scissor jack, a stand with an associated base plate, and a wedge splitter. Furthermore, the design of the stand enables the height of the splitting wedge to be adjusted. Dimensioning of the construction's parts is partly based on shipping costs at USPS and partly on the proper mechanism to function as desired. The log splitter is visualized as a CAD model where the choice of material and color is based on the concept definition and concept generation phase.
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Anténní systém pro bezdrátové mikrofony / Antenna system for wireless microphonesBartoš, Adam January 2018 (has links)
Master's thesis deals with the design of an antenna system for wireless sound transmission used mainly in professional sound reinforcement. The introductory part deals generally with wireless microphones, frequency bands used and proven antenna types. Next, this work deals with signal distribution that is realized using the antenna splitter. The antenna parts is focused on easy production and real usage, therefore were selected antennas with appropriate properties suitable for small series production. This thesis includes simulation of each device, their real construction design and measurements of built prototypes and final products. All three produced devices – the rack splitter, /4 antenna and Helix antenna are fully working, achieve good parameters and are ready for further manufacturing and easy modifications in case of frequency band change requirement. The conclusion includes an overall assessment of the results achieved.
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Automatizace a optimalizace konstrukce a pracovního procesu horizontální štípačky na palivové dřevo / Automatization a optimalization of desing and proces of firewood horizontal log splitterČechman, Jan January 2019 (has links)
Diploma thesis is focused on design and optimalization of log splitter. Thesis consists of search of log splitter types and common used technologies, mechanical design, optimalization, design of propultion system, risk analysis and financial overview. Log splitter is designed to meet needs of automatization. Safety, industrial design and ergonomy has been considered in the design.
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The Effects of Parkinson's on Fixational StabilityMallahan, Erin L. 01 January 2005 (has links)
Parkinson's disease (PD) is a progressive, neurological movement disorder. The stability of eye movements in PD is not well understood but many patients report difficulty doing tasks that require stabilized fixation and gaze. The ability to stabilize an image on the retina is critical is acquiring visual information. The purpose of this study was to compare the stability of fixational eye movements of PD patients to those of age-matched controls. Eye movements during simple fixation tasks were recorded from 66 subjects (ages 52 to 84), and 36 age-matched controls (ages 58-85). The absolute velocity of the fixational eye movements were recorded and correlated to a clinical measure of disease progression as measured by the Unified Parkinson's Disease Rating Scale (UPDRS). Unstable, non-rhythmic eye movements were seen in the PD patients. There were significant differences in the absolute velocity and standard deviation between the control group and the PD group in both the horizontal and vertical directions. The correlation of the absolute velocity to the UPDRS was not significant. Parkinson's disease does appear to affect the stability of eye movements. The instabilities in the eye movements appear to precede body tremor. This could lead to an early method for diagnosis and analysis of the disease.
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Silicon-on-Insulator Polarization Beam Splitter Based on a Taper Asymmetrical Directional CouplerXiao, Min-Yuan 25 July 2012 (has links)
Polarization dependences of optical devices in highly-integrated optical systems become a major problem. To overcome this issue, one can implement polarization diversity scheme to achieve a single polarization on-chip network. One of the essential components in a polarization diversity scheme is the polarization beam splitter (PBS). In this thesis, we will a PBS based on a silicon-on-insulator (SOI) platform with reduced device size and broad operation bandwidth.
We use the three-dimensional Finite-Difference Time-Domain (3D-FDTD) method to perform the simulation. First, we use two asymmetric waveguides to design an asymmetric directional coupler with only TE-like mode phase matching condition. We then tape the lower waveguide to keep the TE-polarized light, and split the TE- and TM- polarized light. By utilizing an asymmetrical directional coupler with a tapered waveguide, we have achieved a 7.3
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Analysis and Design for the Photonic-Crystal-Fiber ComponentsChiang, Jung-Sheng 19 January 2006 (has links)
The dissertation focuses on the analysis and design for the new fiber-optic passive components based on the photonic-crystal-fiber (PCF). The vector boundary element method (VBEM) and the finite-difference time-domain (FDTD) method are employed to the propagation characteristics of PCF components. A novel octagonal microstructured fiber (OMF) with eight air-holes in the first ring has been proposed. The OMF has significantly wider wavelength range for single-mode operation, more circular-like field distribution, and less confinement loss. In addition, a novel compact polarization beam splitter (PBS) based on the twin-elliptical-core PCF (TEC-PCF) has also been proposed. It behaves with high extinction ration and broad bandwidth with significantly short splitter length. The design concept and the coupling mechanism are presented in this dissertation based on the normal-mode coupling theory and VBEM.
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Bose-Einstein condensates in magnetic double well potentialsSchumm, Thorsten 20 February 2006 (has links) (PDF)
Ce manuscrit présente deux réalisations d'un double puit magnétique pour des condensats de Bose-Einstein (CBE) sure une puce atomique. Une approche utilise des pièges statiques, crées par des micro fils (en amènent ?) manipulant les atomes proche a la surface de la puce. Comme dans toute manipes, on observe une fragmentation du nuage atomique, quand on approche les atomes vers la structure piégeant. Cet effet était expliqué par une déviation du courant dans le fil à cause d'une rugosité des bords. Pour éviter la fragmentation, une nouvelle technique de fabrication (lithographie a faisceaux a électrons, évaporation d'or) a été utilisé pour créer des fils d'un section de 700nm et une qualité amélioré. Un CBE a été crée et chargé dans le double puit généré par la nano structure. On a testé le double puit comme séparatrice avec des atomes thermiques. Des nombreuses problèmes techniques nous empêchent pour le moment d'effectuer la manip avec un CBE.<br />La deuxième approche poursuit dans cette thèse combine des pièges magnétique statique avec un champ (RF) magnétique alternant et génère un double puit dans le potentiel habillé. Car ce schéma peut être réalisé loin de la surface de la puce, la fragmentation n'apparaisse pas et on a pu séparer un CBE en deux. Une interféromètre d'ondes a matière est réalisé en recombinant les deux nuages en expansion libre. La figure d'interférence permet de mesurer la phase relative, on trouve une distribution étroite de cette phase et donc la séparation est cohérente. L'évolution de la phase relative est mesurée pendant et après la séparation et contrôlé par déséquilibrant le double puit.
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Konstruktion av en spegelrigg för stereoskopisk 3D i lågbudgetprojekt : En undersökning kring möjligheter och begränsningar med att konstruera en egen lättviktsrigg för stereoskopisk 3D-film i lågbudgetprojekt.Karlsson, David, Korsgren, Tom January 2016 (has links)
Att filma i 3D är en process som kräver mycket kunskap, tid och teknisk utrustning. För att fullständigt behärska detta fält krävs dessutom omfattande praktisk erfarenhet. Denna erfarenhet kan vara svår att få eftersom den ekonomiska investeringen för att filma i 3D ofta är stor. I denna uppsats visar vi att det är möjligt att konstruera en egen 3D-rigg och att filma med vanliga konsumentkameror för att skapa 3D-film. Uppsatsen visar på de begränsningar och svårigheter man stöter på då man bygger sin egen rigg och diskuterar den ekonomiska besparing man kan göra i jämförelse med kommersiella lösningar. Att bygga en egen rigg är tidskrävande och oftast inte att rekommendera i professionella sammanhang. För indieproduktioner, hobby-fotografer eller om man har väldigt specifika krav som ej uppfylls av tillgängliga kommersiella 3D-riggar kan det dock vara motiverat att konstruera sin egen rigg. Kunskapen som uppsatsen redovisar möjliggör ett resonemang för hur bildkvalitet, funktion och ekonomi kan ställas mot varandra i de avvägningar man ställs inför i konstruktionen av en spegelrigg för att filma i 3D.
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