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Dissertations / Theses on the topic 'Gyroid'
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Asghar, Kaleem Abbas. "2D hexagonal and 3D gyroid structured platinum materials." Thesis, University of Reading, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.669697.
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Hussmo, Jonatan, and Roman Schröder. "Experiments, analysis and an application of 3D-printed gyroid structures." Thesis, Örebro universitet, Institutionen för naturvetenskap och teknik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:oru:diva-85935.
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The thesis investigates the mechanical properties of gyroid structures through various experiments and simulations. Gyroid structures consist of an intricate mesh of surfaces and can differ in density and cell size. The mechanical properties of the gyroid structure are inevitably dependent on the density. A convergence between density and the resulting mechanical stiffness of the lattice structure could be applied to a wide range of industrial components. To test the mechanical properties of gyroid structures 3D-printed cubes are compressed in a test machine where stiffness is measured for a range of cubes with different density. The tests are confirmed by a finite element analysis (FEA) and all data is precisely analysed thereafter. A linear increase in density results in a non-linear increase in stiffness where the region between 30 % and 60 % density yields particularly good results. After evaluating results from experiments and simulations, gyroid structure is implemented in one of ABB’s components for a circuit-breaker system to further display its advantages. Four different concepts are presented for the component where the most promising concept reached a weight reduction of 30 percent just by adding gyroid structures. No other design alterations have been made to the component. The results show great potential of being able to reduce the plunger’s weight whilst maintaining desired stiffness. The results of the thesis can be applied widely to develop new methods of optimizing industrial components with additive manufacturing as the gyroid doesn’t need any supportive structure. It is possible to blend gyroid surfaces with other optimization tools such as topology optimization or grading to achieve even higher degrees of weight reduction.Tesen undersöker de mekaniska egenskaperna av gyroidstrukturer genom olika experiment och simuleringar. Gyroidstrukturer består av ett komplext nätverk av ytor och kan variera i densitet och cellstorlek. Dess hållfasthetsegenskaper är givetvis beroende på densiteten. Konvergensen mellan densitet och den resulterande mekaniska styvheten av nätverksstrukturen skulle kunna tillämpas på ett brett spektrum av industriella komponenter. Det är möjligt att reducera vikt eller öka styvhet medan att kunna bibehålla hållfastheten. För att testa hållfasthetsegenskaperna av gyroidstrukturer 3D-printade kuber komprimeras i en tryckmaskin där styvhet mäts för ett antal kuber med olika densitet. Testen bekräftas genom en analys med finita elementmetoden (FEM) och all data utvärderas noggrant därefter. En linjär ökning i densitet leder till en ickelinjär ökning i styvhet där området mellan 30% och 60% densitet ger ett särskilt bra förhållande mellan styvhet och vikt. När resultatet från experimenten och analysen utvärderats, implementeras gyroidstruktur på en av ABB’s komponenter i en strömbrytare för att ytterligare visa dess fördelar. Fyra olika koncept presenteras där det mest lovande konceptet kunde viktoptimeras med 30 procent endast genom att tillägga gyroidstrukturer. Inga andra designändringar har gjorts på komponenten. Resultatet demonstrerar en stor potential när det gäller att viktreducera komponenten utan att tappa nödvändig styvhet. Resultaten av tesen kan användas på många olika sätt för att ta fram nya metoder för optimering av industriella komponenter med additiv tillverkning då gyroiden inte behöver några stödstrukturer. Det är möjligt att blanda gyroidstrukturer med andra optimeringsverktyg såsom topologioptimering eller gradering för att åstadkomma ännu större viktminskningar.
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Scherer, Maik. "Synthesis and applications of double-gyroid-structured functional materials." Thesis, University of Cambridge, 2014. https://www.repository.cam.ac.uk/handle/1810/245302.
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The objective of this work, concerning the template-assisted patterning of functional materials on the nanoscale to enhance specific material properties, is five-fold. Firstly, to develop a highly reproducible synthesis pathway for large quantities of double- gyroid-forming diblock copolymers. Secondly, to replace the previously used fluo- rinated monomers with an inexpensive and environmentally sustainable alternative making large-scale applications feasible. Thirdly, to establish a reliable and fast fabri- cation technique for fully porous gyroidal templates. Fourthly, to replicate these tem- plates with inorganic as well as organic functional materials using electrochemical and atomic layer deposition. Finally, to apply and characterize these novel double-gyroid- structured materials in devices such as photovoltaic devices, electrochromic displays, and supercapacitors. The first part of this thesis introduces the different techniques of modern nanotechnol- ogy employed in three-dimensional nanopatterning of functional materials and seeks to highlight the possibilities and advantages of using self-assembled, mesoporous polymeric templates for this purpose. Chapter 2 explores the fascinating gyroidal intermaterial dividing surfaces formed by self-assembling systems, such as microphase separating di- block copolymers. Chapter 3 focuses on the synthesis of double-gyroid-forming diblock copolymers consisting of poly(4-X-styrene) and poly(lactic acid) via atom transfer radi- cal and organocatalytic ring-opening polymerization using a bifunctional initiator. The preparation of mesoporous templates with double-gyroid morphology based on a rapid thermal annealing protocol is described in Chapter 4. Importantly, it is shown that copolymers prepared from inexpensive, non-substituted styrene can yield fully porous thin films. Chapter 5 reports the template-assisted electrodeposition of metal oxides, such as V2O5, using the previously prepared voided styrenic templates. Further, the perfor- mance of these materials as electrodes in electrochromic displays and supercapacitors is tested. Chapter 6 describes an alternative approach to obtain double-gyroid-structured metal ceramics via the post-nanostructuring thermal oxidation of electroplated metals. Nickel is chosen to demonstrate this highly versatile fabrication route and to study the nanoscale Kirkendall effect of three-dimensional structures. Further, the electrochromic performance of NiO is investigated. Chapter 7 deals with yet another electrodeposition technique, namely the electropolymerization of conjugated polymers. Identification of suitable solvents for the templated electrosynthesis and the subsequent template dis- solution enable the three-dimensional nanopatterning of PPy, PEDOT, and PT. The refilling of the organic template via atomic layer deposition, including the necessary chemically modification of the styrenic scaffold for an improved thermal resistance and surface functionality, is discussed in Chapter 8.
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Zhang, Botao. "Design of Variable-Density Structures for Additive Manufacturing Using Gyroid Lattices." University of Cincinnati / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1535374427634743.
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Kang, Min Jeong M. Eng Massachusetts Institute of Technology. "High performance curtain wall mullion section design with various densities of gyroid." Thesis, Massachusetts Institute of Technology, 2016. http://hdl.handle.net/1721.1/107061.
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Thesis: M. Eng., Massachusetts Institute of Technology, Department of Civil and Environmental Engineering, 2016.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 87-91).
The thermal bridge problem in building fagades has become a topic of interest as the energy performance of building enclosure design required improvements with a global lead in sustainable building design. Curtain wall fagade systems are widely used for recent high-rise buildings, and the thermal bridge issue occurs mainly within the aluminum frame of the curtain wall system. In addition to the thermal bridging effects, the conventional curtain wall fagade designs have limitations in increasing the stiffness of the mullion. As to address the lack of an innovative solution to solve both issues, this thesis proposes utilizing a cellular structure in mullion design. In particular, this thesis has selected a single-gyroid structure, which is an open cell foam structure that has the minimum surface area necessary to span a region of space. The thesis explores various aspects of the application that extend from a rapid modeling method of gyroid structure, experiments, and simulations along with theoretical values for mechanical and thermal properties of gyroid, to topology optimization of the various densities of gyroid in the composite structure. The results are expected to improve the curtain wall designs with future experimental verifications.
by Min Jeong Kang.
M. Eng.
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Dair, Benita Jean 1973. "Characterization, orientation, and deformation behavior of the double gyroid phase in elastomeric triblock copolymers." Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/85251.
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Deng, Guodong. "Self-Assembly of Poly(Ethylene Oxide)-Block-Poly(Ethyl Acrylate)-Block-Polystyrene with Phenolic Resins." University of Akron / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=akron1399044329.
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Mille, Christian. "Templating and self-assembly of biomimetic materials." Doctoral thesis, Stockholms universitet, Institutionen för material- och miljökemi (MMK), 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-80459.
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This thesis focuses on the use of biomolecular assemblies for creating materials with novel properties. Several aspects of biomimetic materials have been investigated, from fundamental studies on membrane shaping molecules to the integration of biomolecules with inorganic materials. Triply periodic minimal surfaces (TPMS) are mathematically defined surfaces that partition space and present a large surface area in a confined space. These surfaces have analogues in many physical systems. The endoplasmic reticulum (ER) can form intricate structures and it acts as a replica for the wing scales of the butterfly C. rubi, which is characterized by electron microscopy and reflectometry. It was shown to contain a photonic crystal and an analogue to a TPMS. These photonic crystals have been replicated in silica and titania, leading to blue scales with replication on the nanometer scale. Replicas analyzed with left and right handed polarized light are shown be optically active. A macroporous hollow core particle was synthesized using a double templating method where a swollen block copolymer was utilized to create polyhedral nanofoam. Emulsified oil was used as a secondary template which gave hollow spheres with thin porous walls. The resulting material had a high porosity and low thermal conductivity. The areas of inorganic materials and functional biomolecules were combined to create a functional nanoporous endoskeleton. The membrane protein ATP synthase were incorporated in liposomes which were deposited on nanoporous silica spheres creating a tight and functional membrane. Using confocal microscopy, it was possible to follow the transport of Na+ through the membrane. Yop1p is a membrane protein responsible for shaping the ER. The protein was purified and reconstituted into liposomes of three different sizes. The vesicles in the 10-20 nm size range resulted in tubular structures. Thus, it was shown that Yop1p acts as a stabilizer of high curvature structures.At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 2: Manuscript. Paper 3: Submitted. Paper 4: Submitted. Paper 5: Submitted.
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Darbyshire, Alice. "Twin control moment gyros for small satellites." Thesis, University of Surrey, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.502639.
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Ghalib, Sara, Daniel Holmberg, Mattias Lundén, Karin Rudström, and Jana Zachrisson. "Nya lysande detektionstekniker : Undersökning hur Gyros känsliga instrument kan bli ännu känsligare." Thesis, Uppsala universitet, Institutionen för biologisk grundutbildning, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-155988.
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Immunoassayer är en väldigt vanlig metod för koncentrationsbestämning av biomolekyler. Denna metod nyttjar antikroppars affinitet för vissa analyter. I detta projekt har det undersökts om Gyros AB:s detektionsinstrument kan göras känsligare. Flera förslag har tagits fram genom efterforskning i artiklar och intervjuer med personer insatta inom området. De metoder som projektgruppen valt att presentera för företaget är enzymbaserad immunoassay med fluorescerande substrat samt multipel inmärkning av antikroppar, vilket vi tror kommer bidra till att försärka den fluorescerande signalen. Immobilisering av antikroppar med hjälp av traptavidin är ytterligare ett framtaget förbättringsförslag som syftar till att bidra med starkare och förlängd immobilisering av antikroppar till den fasta fasen i immunoassay. Flertalet andra metoder har undersökts såsom detektion med hjälp av radioaktivitet och kemiluminiscens. Inga fortsatta studier gjordes på grund av svårigheter att anpassa metoderna till de nuvarande instrumenten. Vi tror att de förslag på metodförbättringar som vi föreslår kan förbättra känsligheten på Gyros mätningar om de implementeras på den nuvarande plattformen.
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Björk, Alexander. "Control of Multibody Machines usingRate Gyros and Optronics." Thesis, Umeå universitet, Institutionen för tillämpad fysik och elektronik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-155447.
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This project deals with design and prototype testing of a reversing car trailer systemequipped with a rate gyro and optronics to locate a target and drive to it. Simulink isused for developing and implementing the control system, it was also used to remotelyoperate the vehicle with a Man-in-the-Loop input. Given a starting position the user cancontrol a servo holding a laser range finder and a laser pointer to find a suitable target,and then lock the vehicle on it to later make it autonomously approach it. The finished car trailer system can, when driving straight backwards, reach the destinationwithin the vicinity of 10 ± 7 cm from a starting position 3 m away. When reversingto a target with an angular offset the accuracy and precision is decreasing. Provided the short time frame for a project that covers both designing, building andtesting of the final product the robot was experimentally tested only a few times. Moretesting is necessary to show limitations in design and implementation. The combination of experimental results and simulations this project has resulted inshows a proof of concept for this type of autonomous vehicle, although further improvementsand tests are vital to improve performance and reliability.Detta projekt innefattar design, prototyputveckling, testning, och utvärdering av ettbackande bil- och trailersystem som använder rategyron och opronik för att lokaliseraoch köra till ett bestämt mål. Simulink används för att utveckla och implementerastyrsystemet och det används även för att trådlöst styra fordonet med Man-in-the-Loopindata. Givet en startposition kan användaren styra ett servo som håller en avståndsensoroch laserpekare för att hitta ett lämpligt mål, låsa på målet, och sedan få fordonet atthelt autonomt köra fram till det. Det färdiga bil och släpfordonet kan, när det backar rakt bak, nå ett mål inom en närhetav 10 ± 7 cm från en startposition 3 m bort. När fordonet backar med en vinkeloffsetminskar noggrannhet och precision. Given den korta tidsramen för ett projekt som involverar design, prototypbygge och testningav slutprodukten, blev roboten experimentellt testad under endast ett fåtal försök.Mer tester är nödvändiga för att visa tillkortakommanden för design och implementation. Kombinationen av de experimentella resultat och simuleringar detta projekt har resulterati ger bevis för att denna typ av autonoma fordon fungerar, även om fortsatt utvecklingoch förbättringar är vitala för att öka prestanda och tillförlitlighet.4
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Istomin, A. E., and N. E. Khatsko. "Statistical research and simulation of MEMS gyros measurements." Thesis, Національний авіаційний університет, 2016. http://repository.kpi.kharkov.ua/handle/KhPI-Press/44403.
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This article provides results of the statistical analysis and numerical evaluation of noise level components in the MEMS gyroscopes measurements. The Simulink-model of measurement errors for the ADIS16250 angular rate sensors was build, and test data and simulation results were analyzed.
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Le, Gall Quentin. "The Usage of Gyros in North Finding Systems." Thesis, KTH, Farkost och flyg, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-209201.
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As surprising as it may seem, accurate north finding, with an error of only several milli-radian, is still a very difficulttask and has been achieved only with very expensive systems. On the contrary, there are very simple systems that give theazimuth with an angular error five times superior but for a price a hundred times inferior. Moreover, these systems generally arenon-autonomous (i.e. they are environment dependent and can lose their precision in many situations). This assessment leads tothe following relevant question: Is it possible to design a north finding system with good precision, for a moderated cost and thatworks in any situation?This report presents and evaluates a solution which attempts to answer this problem. This solution is based on a gyrocompassingprinciple: a gyro measures the earth’s angular velocity in order to find the azimuth. This solution can be implementedfollowing several methods, this report presents and compares two of these implementations: Maytagging and Carouseling. Thecomparison is made thanks to a theoretical study, a computer simulation and tests on a real model designed for this report.Carouseling allows us, in theory, to reach an accurate azimuth, but puts mechanical constraints on the system. Maytaggingimplementation seems adapted considering trade-off between precision and cost. Further improvements on gyros will certainlymake systems based on gyro-compassing the most efficient autonomous systems for north finding.In this report, precisions reached by the different implementations are not made explicit for confidentiality reasons.
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Prassinos, George. "Design of control moment gyros for agile small satellites." Thesis, University of Surrey, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.548359.
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Björk, Alexander. "Control of Multibody Machines using Rate Gyros and Optronics." Thesis, Umeå universitet, Institutionen för tillämpad fysik och elektronik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-155417.
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This project deals with design and prototype testing of a reversing car trailer systemequipped with a rate gyro and optronics to locate a target and drive to it. Simulink isused for developing and implementing the control system, it was also used to remotelyoperate the vehicle with a Man-in-the-Loop input. Given a starting position the user cancontrol a servo holding a laser range finder and a laser pointer to find a suitable target,and then lock the vehicle on it to later make it autonomously approach it. The finished car trailer system can, when driving straight backwards, reach the destinationwithin the vicinity of 10 ± 7 cm from a starting position 3 m away. When reversingto a target with an angular offset the accuracy and precision is decreasing. Provided the short time frame for a project that covers both designing, building andtesting of the final product the robot was experimentally tested only a few times. Moretesting is necessary to show limitations in design and implementation. The combination of experimental results and simulations this project has resulted inshows a proof of concept for this type of autonomous vehicle, although further improvementsand tests are vital to improve performance and reliability.Detta projekt innefattar design, prototyputveckling, testning, och utvärdering av ettbackande bil- och trailersystem som använder rategyron och opronik för att lokaliseraoch köra till ett bestämt mål. Simulink används för att utveckla och implementerastyrsystemet och det används även för att trådlöst styra fordonet med Man-in-the-Loopindata. Givet en startposition kan användaren styra ett servo som håller en avståndsensoroch laserpekare för att hitta ett lämpligt mål, låsa på målet, och sedan få fordonet atthelt autonomt köra fram till det. Det färdiga bil och släpfordonet kan, när det backar rakt bak, nå ett mål inom en närhetav 10 ± 7 cm från en startposition 3 m bort. När fordonet backar med en vinkeloffsetminskar noggrannhet och precision. Given den korta tidsramen för ett projekt som involverar design, prototypbygge och testningav slutprodukten, blev roboten experimentellt testad under endast ett fåtal försök.Mer tester är nödvändiga för att visa tillkortakommanden för design och implementation. Kombinationen av de experimentella resultat och simuleringar detta projekt har resulterati ger bevis för att denna typ av autonoma fordon fungerar, även om fortsatt utvecklingoch förbättringar är vitala för att öka prestanda och tillförlitlighet.
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Sinitsyn, Oleksandr V. "Analyses of advanced concepts in multi-stage gyro-amplifiers and startup in high-power gyro-oscillators." College Park, Md. : University of Maryland, 2005. http://hdl.handle.net/1903/3228.
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Thesis (Ph. D.) -- University of Maryland, College Park, 2005.Thesis research directed by: Electrical Engineering. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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Yoon, Hyungjoo. "Spacecraft Attitude and Power Control Using Variable Speed Control Moment Gyros." Diss., Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/4850.
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A Variable Speed Control Moment Gyro (VSCMG) is a recently
introduced actuator for spacecraft attitude control.
As its name implies, a VSCMG is essentially a single-gimbal
control moment gyro (CMG) with a flywheel allowed to have variable spin
speed. Thanks to its extra degrees of freedom, a
VSCMGs cluster can be used to achieve additional objectives, such
as power tracking and/or singularity avoidance, as well as
attitude control.
In this thesis, control laws for an integrated power/attitude
control system (IPACS) for a satellite using VSCMGs are
introduced.
The power tracking objective is achieved by storing or releasing the kinetic energy
in the wheels. The proposed control algorithms perform both the attitude
and power tracking goals simultaneously.
This thesis also provides a singularity analysis and avoidance method using
CMGs/VSCMGs. This issue is studied for both the cases of attitude tracking with and without a power
tracking requirement. A null motion method to avoid singularities is
presented, and a criterion is developed to determine the momentum region
over which this method will successfully avoid singularities.
The spacecraft angular velocity and attitude control problem using a single
VSCMG is also addressed.
A body-fixed axis is chosen to
be perpendicular to the gimbal axis, and it is controlled to aim at an arbitrarily given inertial direction,
while the spacecraft angular velocity is stabilized.
Finally, an adaptive control algorithm for the spacecraft attitude tracking in case
when the actuator parameters, for instance the spin axis directions, are uncertain is developed.
The equations of motion in this case
are fully nonlinear and represent a Multi-Input-Multi-Output (MIMO) system.
The smooth projection algorithm is applied to keep the parameter estimates inside
a singularity-free region.
The design procedure can also be easily applied to general MIMO dynamical systems.
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Miao, Yingyu. "Advanced overmoded circuits for gyro-amplifiers." College Park, Md. : University of Maryland, 2004. http://hdl.handle.net/1903/1370.
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Thesis (Ph. D.) -- University of Maryland, College Park, 2004.Thesis research directed by: Electrical Engineering. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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Lively, Charles Wesley III. "Performance analysis and modeling of GYRO." Texas A&M University, 2006. http://hdl.handle.net/1969.1/4335.
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Efficient execution of scientific applications requires an understanding of how system features
impact the performance of the application. Performance models provide significant insight into
the performance relationships between an application and the system used for execution. In
particular, models can be used to predict the relative performance of different systems used to
execute an application. Recently, a significant effort has been devoted to gaining a more detailed
understanding of the performance characteristics of a fusion reaction application, GYRO.
GYRO is a plasma-physics application used to gain a better understanding of the interaction of
ions and electrons in fusion reactions. In this thesis, we use the well-known Prophesy system to
analyze and model the performance of GYRO across various supercomputer platforms. Using
processor partitioning, we determine that utilizing the smallest number of processors per node is
the most effective processor configuration for executing the application. Further, we explore
trends in kernel coupling values across platforms to understand how kernels of GYRO interact.
In this work, experiments are conducted on the supercomputers Seaborg and Jacquard at
the DOE National Energy Research Scientific Computing Center and
the supercomputers DataStar P655 and P690 at the San Diego Supercomputing
Center. Across all four platforms, our results show that utilizing one processor per node (ppn)
yields better performance than full or half ppn usage. Our experimental results also show that
using kernel coupling to model and predict the performance of GYRO is more accurate than
summation. On average, kernel coupling provides for prediction estimates that have less than a
7% error. The performance relationship between kernel coupling values and the sharing of
information throughout the GYRO application is explored by understanding the global
communication within the application and data locality.
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Björck, Olof. "Analyzing gyro data based image registration." Thesis, Uppsala universitet, Institutionen för informationsteknologi, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-397459.
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An analysis of gyro sensor data with regards to rotational image registration is conducted in this thesis. This is relevant for understanding how well images captured with a moving camera can be registered using only gyro sensor data as motion input. This is commonly the case for Electronic Image Stabilization (EIS) in handheld devices. The theory explaining how to register images based on gyro sensor data is presented, a qualitative analysis of gyro sensor data from three generic Android smartphones is conducted, and rotational image registration simulations using simulated noise as well as real gyro sensor data from the smartphones are presented. An accuracy metric for rotational image registration is presented that measures image registration accuracy in pixels (relevant for frame to frame image registration) or pixels per second (relevant for video EIS). This thesis shows that noise in gyro sensor data affects image registration accuracy to an extent that is noticeable in 1080x1920 resolution video displayed on larger monitors such as a computer monitor or when zooming digitally, but not to any significant extent displayed on a monitor the size of a regular smartphone display without zooming. Different screen resolutions and frame rates will affect the image registration accuracy and would be interesting to investigate in further work. Ways to improve the gyro sensor data would also be interesting to investigate.
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Thienel, Julie K. "Nonlinear observer/controller designs for spacecraft attitude control systems with uncalibrated gyros." College Park, Md. : University of Maryland, 2004. http://hdl.handle.net/1903/1401.
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Thesis (Ph. D.) -- University of Maryland, College Park, 2004.Thesis research directed by: Aerospace Engineering. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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Leszczynski, Matthew J. "Improving the performance of MEMS gyros via redundant measurements: theory and experiments." Thesis, Monterey, California: Naval Postgraduate School, 2014. http://hdl.handle.net/10945/44605.
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Approved for public release; distribution is unlimitedA redundant sensor array is a device composed of more than one sensor of a given type, for example an array of rate gyroscopes. Previous work has shown that redundancy can enhance the failure tolerance of the sensor suite and can also be leveraged to improve the accuracy of the measurements. This thesis further explores the possibility of improving the performance of low-cost micro-electro-mechanical (MEMS) gyroscopes using the redundancy concept. To this end, an experimental sensor array test bed is constructed that allows data from up to 12 three degrees of freedom MEMS gyroscopes to be acquired and combined under various geometric configurations. By organizing the MEMS gyroscopes in ideal geometric configurations, it is shown how the effects of sensor noise can be reduced in order to increase the precision of the measurements. Experiments using the constructed sensor array test bed show that the 1-σ sensor noise can be reduced by nearly 65 percent through the proper combination of multiple measurements using ten 3 degrees of freedom gyros. It is further observed that realizing this improvement relies, in part, upon accurate estimation of the sensor bias. This aspect motivates future work on bias estimation schemes for arrays of sensors.
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Bae, Sungkoo. "GLAS spacecraft attitude determination using CCD star tracker and 3-axis gyros /." Digital version accessible at:, 1998. http://wwwlib.umi.com/cr/utexas/main.
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Kimber, Mark John. "Calibration and use of surveying gyro systems." Thesis, University of Nottingham, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.240485.
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Doerr, Christopher Richard. "Optical reference gyro characterization and performance enhancement." Thesis, Massachusetts Institute of Technology, 1990. http://hdl.handle.net/1721.1/77756.
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Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1990.Includes bibliographical references (p. 154).
by Christopher Richard Doerr.
M.S.
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Gonçalves, Pedro Filizola Sousa Maia. "Attitude determination of a multirotor aerial vehicle using camera vector measurements and gyros." Instituto Tecnológico de Aeronáutica, 2014. http://www.bd.bibl.ita.br/tde_busca/arquivo.php?codArquivo=3132.
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The employment of embedded cameras in navigation and guidance of Unmanned Aerial Vehicles (UAV) has attracted the focus of many academic researches. In particular, for the multirotor UAV, the camera is widely employed for applications performed at indoor environments, where are less access to the GNSS signal and higher electromagnetic interference. Nevertheless, in most researches, the images captured by the camera are usually adopted to aid in the linear position/velocity estimation, but not specifically for assisting in the attitude determination process. This dissertation proposes an attitude determination method for multirotor UAVs using pairs of vector measurements taken from one downward facing strapdown camera and angular velocity measurements from gyros. The method consists in three modules. The first detects and identifies landmarks from the captured images. The second module computes the vector measurements related to the direction between the landmarks and the camera. The third module executes the attitude estimation from the vector measurements given by the second module. The employed estimation method consists in a version of the Multiplicative Extended Kalman Filter (MEKF) with sequential update. The proposed method was evaluated via Monte Carlo simulations using Simulink 3D Animation. During the evaluation, the method presented effectiveness and satisfactory results in most of the simulated cases. Finally, future works are suggested for the potential continuation of this research.
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Berner, Reimer. "Control moment gyro actuator for small satellite applications." Thesis, Stellenbosch : University of Stellenbosch, 2005. http://hdl.handle.net/10019.1/2144.
Full textAbstract:
Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2005.The aim of the thesis is to design a Control Moment Gyro (CMG) actuator which can be used in small satellite applications. The hardware and software of the CMG has to be designed according to specifications given. A satellite fitted with these CMGs has to be able to do a 30 degree rotation within 10 seconds.
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Herrera, C. Daniel. "Gyro: juego didáctico para construir volúmenes geométricos deformables." Tesis, Universidad de Chile, 2006. http://repositorio.uchile.cl/handle/2250/100804.
Full textAbstract:
El mejorar la calidad de la educación es un
objetivo fundamental dentro de nuestras
sociedades, donde cada día se exige poseer
mayores capacidades y aptitudes para poder
desenvolvernos con mayor libertad en el
mundo moderno. Dentro de este marco, las
políticas gubernamentales han intentado
desarrollar nuevas estrategias para atacar este
problema, donde la principal propuesta ha
sido la Reforma Educacional, cuestionada en
estos días por los pobres resultados que ha
obtenido desde su implementación.
Si bien la creación y puesta en marcha de la
Reforma es un gran paso que ha dado el
gobierno para mejorar la calidad de la
educación, es responsabilidad de todos, como
parte de la sociedad en que vivimos, aportar
desde nuestras profesiones hacia ese fin
común. El presente proyecto se enmarca
dentro de este compromiso social y pretende
generar un aporte desde la perspectiva del
diseño industrial, en el mejoramiento de
aspectos puntuales de la enseñanza y el
aprendizaje de matemáticas, específicamente
en el área de geometría.
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Dao, David. "NUMERICAL COMPUTATIONS FOR ADIABATIC PARTICLE MOTION : Numeriska beräkningar för adiabatisk partikelrörelse." Thesis, Uppsala universitet, Institutionen för teknikvetenskaper, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-200589.
Full textAbstract:
Axisymmetric mirrors have no collision free radial transport, but such magnetic fields may have problems with plasma stability (the tearing instability in particular). There are some means to improve plasma stability in axisymmetric mirrors by magnetic expander tanks or axisymmetric divertors, but plasma stability can still be a challenge in axisymmetric mirrors. An alternative is to use quadrupolar magnetic fields as a robust method to overcome the stability issues. A price may then be increased radial transport if the magnetic field design is done without strict consideration of asymmetries, which could result from manufacturing errors.The computations have been done with a hybrid reactor scenario in mind. Such a case have less demands for confinement, but the demands are still challenging. Confinement for about 200 longitudinal bounces is required in a hybrid reactor. The computations carried out here have confirmed that axial asymmetry may become dangerous for plasma confinement in quadrupolar mirror machines. Asymmetry in the range of a few percentage relative error will almost surely result in a too strong radial leakage (at least without a radial electric field). The computational results made in this paper may suggest that if the manufacturing error is kept below 0.15% relative error throughout the plasma confinement region, there is then a some margin for sufficient radial confinement quality. Such accuracies ought to be possible to achieve in the manufacturing process, possible combined with compensating magnetic fields to maintain a precise magnetic field design. The precision requirements in the design is still a bit challenging.
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McManus, Christine D. "Development, verification and experimental analysis of high-fidelity mathematical models for control moment gyros." Thesis, Monterey, California : Naval Postgraduate School, 2011. http://hdl.handle.net/10945/28670.
Full textAbstract:
In the operation of CMGs there exists a concept called “back drive,” which represents a case where the coupling effects of the angular velocity of the body and the angular momentum of the CMG overwhelm the input torque and result in a lack of control. This effect is known but not well documented or studied in the literature. Starting from first principles, this thesis derives the full nonlinear dynamical equations for CMGs. These equations contain significantly more terms than are found in the literature. As a means to understand the implications of these terms, a reduced order model is derived. The full and reduced models are then validated by means of extensive simulations. Finally, experimental verification of the models confirms the finding that the reduced order model provides a reasonably high fidelity for dynamics.
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Guaraldi, Irene. "Hydraulic evaluation of the gyro electric wave energy converter." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2015. http://amslaurea.unibo.it/8427/.
Full textAbstract:
Motivation
Thanks for a scholarship offered by ALma Mater Studiorum I could stay in Denmark for six months during which I could do physical tests on the device Gyro PTO at the Departmet of Civil Engineering of Aalborg University.
Aim
The goal of my thesis is an hydraulic evaluation of the device: Gyro PTO, a gyroscopic device for conversion of mechanical energy in ocean surface waves to electrical energy. The principle of the system is the application of the gyroscopic moment of flywheels equipped on a swing float excited by waves.
The laboratory activities were carried out by: Morten Kramer, Jan Olsen, Irene Guaraldi, Morten Thøtt, Nikolaj Holk.
The main purpose of the tests was to investigate the power absorption performance in irregular waves, but testing also included performance measures in regular waves and simple tests to get knowledge about characteristics of the device, which could facilitate the possibility of performing numerical simulations and optimizations.
Methodology
To generate the waves and measure the performance of the device a workstation was created in the laboratory. The workstation consist of four computers in each of wich there was a different program.
Programs have been used : Awasys6, LabView, Wave lab, Motive optitrack, Matlab, Autocad
Main Results
Thanks to the obtained data with the tank testing was possible to make the process of wave analisys. We obtained significant wave height and period through a script Matlab and then the values of power produced, and energy efficiency of the device for two types of waves: regular and irregular. We also got results as: physical size, weight, inertia moments, hydrostatics, eigen periods, mooring stiffness, friction, hydrodynamic coefficients etc.
We obtained significant parameters related to the prototype in the laboratory after which we scale up the results obtained for two future applications: one in Nissun Brending and in the North Sea.
Conclusions
The main conclusion on the testing is that more focus should be put into ensuring a stable and positive power output in a variety of wave conditions. In the irregular waves the power production was negative and therefore it does not make sense to scale up the results directly. The average measured capture width in the regular waves was 0.21 m. As the device width is 0.63 m this corresponds to a capture width ratio of: 0.21/0.63 * 100 = 33 %. Let’s assume that it is possible to get the device to produce as well in irregular waves under any wave conditions, and lets further assume that the yearly absorbed energy can be converted into electricity at a PTO-efficiency of 90 %. Under all those assumptions the results in table are found, i.e. a Nissum Bredning would produce 0.87 MWh/year and a North Sea device 85 MWh/year.
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Buhaiu, Andrei. "Radio Frequency Remote Control Unit with Gyro and Accelerometer." Thesis, Linköpings universitet, Programvara och system, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-100518.
Full textAbstract:
Today digital TV receivers (Set-Top-Boxes) are mainly controlled by IR-based remote control units (RCUs). With new services emerging in thereceivers where better browsing and pointing abilities are desirable (VODservices, Web services, games etc), one solution is a new type of RF remotecontrol. An RF RCU has a number of advantages, e.g. when in range, ithas 100% reliable transmission, it is not sensitive to direction, and it doesnot require a free way to the receiver (i.e. it allows the receiver to be hiddenbehind the TV-set or in a cabinet).
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Puri, Varun. "Tightly coupled GPS-gyro integration for spacecraft attitude determination." Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/50315.
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Constable, David Alexander. "The numerical and experimental investigation of gyro-multiplier configurations." Thesis, University of Strathclyde, 2013. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=19533.
Full textAbstract:
This thesis examines the feasibility of two different configurations of gyromultiplier, both of which operate at the fourth harmonic of the electron cyclotron frequency. The full numerical modelling and design of components for the testing of a novel, single cavity gyro-multiplier experiment has been documented. In addition, numerical simulations of a configuration featuring three distinct cavity sections have also been conducted. The introduction of an eight-fold azimuthal corrugation into the walls of a cylindrical cavity allows for the realisation of a single cavity gyro-multiplier arrangement, with generation of 2nd harmonic, TE2,2, and 4th harmonic, TE4,3, resonances, at frequencies of 37.5 GHz and 75 GHz, respectively. The interaction region is of mean radius, 8 mm, with a corrugation depth, 0.7 mm, and is 39 mm in length. The idealised electron beam utilised is of voltage, 60 kV, with current between 5 A and 10 A, confined in a magnetic field of ~0.7 T. Separation of the two emission frequencies was intended through the use of a 6 mm length cut-off taper; however, mode conversion to two above cut-off modes has been numerically demonstrated. The power contained in the 4th harmonic has been estimated at ~10-50 W. Extension of the output taper has proven to be sufficient to reduce the mode converted signals by an order of magnitude, while not impinging on the propagation of the 4th harmonic signal. The design and simulation of a knife-edge electron gun and kicker system has also been performed, with the final beam predicted to have a velocity spread of ~ 19%. In order to demonstrate the "cold" response of the interaction region to the 2nd harmonic signal, the design, construction and testing of several additional components are also documented. Novel slotted wall mode converters, capable of generating TEm,1 modes from a rectangular TE1,0 input signal, have demonstrated high spectral purity and large, ~10% bandwidth. A set of TE2,1 launchers, of 3.98 mm radius, operating between 37-41 GHz have demonstrated ~56% conversion efficiency, while a similar set for the TE4,1 mode, of 3.78 mm radius, demonstrated ~ 20% conversion efficiency, between 70-80 GHz. A set of ripple wall mode converters, of maximum radius, 8.7 mm, featuring a 20 period, axial sinusoidal ripple, of depth 0.30 mm, designed to convert the TE2,1 mode to a TE2,2, have also been demonstrated. These converters display ~20 MHz bandwidth, at ~38 GHz. Using these couplers demonstrated the corrugated interaction region dispersion was insensitive to the polarisation of incident quadrupole modes, in keeping with theory. By examining a gyro-multiplier setup with three distinct cavity sections, it has been demonstrated that by operating the first and third cavities at the fundamental harmonic, effective generation of a 4th harmonic signal can be realised from a second cavity of radius slightly larger than that of the initial cavity. T he interaction regions examined were of radius 0.7 mm, 0.783 mm, and 1.5 mm, and of lengths 2.4 mm, 2.4mm and 3.6 mm, respectively. By using an idealised electron beam of voltage, 80 kV, beam current of 0.7 A, and pitch factor of 1.4, generation of the TE1,2 and TE1,3 modes at a fundamental frequency of 342.5 GHz, and 4th harmonic, polarised in the TE4,6 mode at a frequency of 1.37 THz has been predicted, for a modest confining magnetic field of ~14.15 T. Although sensitive to the magnitude of the applied field, the maximum power contained in the 4th harmonic signal has been estimated to be 120 W.
35
Price, William D. "Control system of a three DOF Spacecraft Simulator by vectorable thrusters and control moment GYROS." Thesis, Monterey, Calif. : Naval Postgraduate School, 2006. http://bosun.nps.edu/uhtbin/hyperion-image.exe/06Dec%5FPrice.pdf.
Full textAbstract:
Thesis (M.S. in Astronautical Engineering and Astronautical Engineer Degree)--Naval Postgraduate School, December 2007.Thesis Advisor(s): Romano, Marcello. "December 2006." Description based on title screen as viewed on March 12, 2008. Includes bibliographical references (p. 79-80). Also available in print.
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Thornton, Blair. "The development of Zero-G class underwater robots : unrestricted attitude control using control moment gyros." Thesis, University of Southampton, 2006. https://eprints.soton.ac.uk/142569/.
Full textAbstract:
The ‘Zero-G’ is designated as a new class of underwater robot that is capable of unrestricted attitude control. A novel control scheme based on internal actuation using Control Moment Gyros (CMGs) is proposed to provide Zero-G Class Autonomous Underwater Vehicles (AUVs) with this unique freedom in control. The equations of motion for a CMG actuated underwater robot are derived and a nonlinear feedback control law formulated based on energy considerations of the system’s coupled dynamics. Singularities, redundancy and null motion are discussed in the context of CMGs and a mathematical escapability condition is developed based on the differential geometry of null motion. A comprehensive geometric study of the singularities of a CMG pyramid is performed and together with considerations of the inverse kinematics of attitude control form the basis of a global steering law that exactly achieves the desired torques, whilst guaranteeing real-time singularity avoidance within a constrained workspace. The development of the CMG actuated Zero-G Class underwater robot IKURA is described. This is the first Zero-G Class prototype and is the first application of CMGs to underwater robots. A series of experiments to demonstrate the practical application of CMGs and verify the associated theoretical developments is described. The open-loop dynamics of the system and the exactness and real-time applicability of the CMG steering law are verified. Experiments are carried out to assess the performance of the proposed control law by comparing the response of the robot to that using alternative control laws that neglect the hydrodynamic interactions of the body and the coupled motion of the CMGs and body respectively. The control law demonstrates a faster response with a smaller overshoot for less overall control activity than the alternative methods. The ability to actively stabilise the passively unstable translational dynamics of the robot are verified. Next, the unrestricted attitude control capability is confirmed with the robot demonstrating the necessary range of attitude control to adopt and maintain any attitude on the surface of a sphere. Finally, the ability to stabilise any attitude while translating in surge is confirmed with the robot performing vertically pitched diving and surfacing in surge. This is the first time an underwater robot has performed such a manoeuvre. This research demonstrates that CMGs are capable of actively stabilising the passively unstable dynamics of an underwater robot with essentially zero-righting moment and are capable of providing it with unrestricted attitude control. The three-dimensional manoeuvring capabilities allow Zero-G Class underwater robots to plan and optimise their missions in a fully threedimensional manner, in a way that has not been possible previously. This study concludes that the application of CMGs for attitude control opens up a path to develop sophisticated Zero-G Class underwater robots and their application to new fields of underwater research.
37
Rowlands, David Hywel. "A cusp gun and novel mircowave components for gyro-devices." Thesis, University of Strathclyde, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.510906.
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Li, Xiang. "Study of high-harmonic gyro-devices in the THz range." Thesis, Queen Mary, University of London, 2016. http://qmro.qmul.ac.uk/xmlui/handle/123456789/23214.
Full textAbstract:
In the terahertz (THz) band, high-harmonic operations of gyro-devices are attractive for the great potential to reduce the required external magnetic field strength, which is proportional to the oscillation frequency but inversely proportional to the operational harmonics. This thesis focuses on the study of high-harmonic operation of the gyro-devices. Specifically, a high-harmonic large-orbit gyrotron (LOG) and the output system for a gyro-multiplier will be investigated. Firstly, the complex-cavity gyrotron, which is the foundation of the gyro-multiplier scheme, is studied by programming and computer simulation. The computer code and the complex-cavity operation are then verified by three-dimensional (3D) Particle-In-Cell (PIC) simulation. The code can be used as a preliminary design tool of the beam-wave interaction cavity for both the LOG and the gyro-multiplier. Secondly, a high-harmonic LOG operating with the TEm,1,1 modes (m=4-9) has been designed and investigated. It is shown that by proper choice of the operation parameters, selective excitation of oscillation from the fourth to the ninth harmonic of the electron cyclotron resonance can be achieved with kW-level output power from 230 GHz to 465 GHz. By enabling the high-harmonics operation, the required external magnetic field strengths are reduced to the range between 2.6 T to 3.1 T. The parameter variation study is also performed to provide a general conclusion of the high-harmonic LOGs operation. Thirdly, this thesis presents the investigation of a quasi-optical output system for a fourth-harmonic gyro-multiplier in the THz band. A dual-harmonic quasi-optical mode converter (DQMC) and a frequency selective surface (FSS) are employed within this system. It is shown that the optimal design of the DQMC requires a special mode selection in the gyro-multiplier. The high-pass FSS is designed, fabricated and experimentally verified by a THz-TDS system. It is demonstrated that the designed FSS is capable of handling the high-power output from the gyro-multiplier.
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Gruman, Fredrick S. (Fredrick Steven). "Stability analysis of the optical reference gyro discrete noise eliminator." Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/36459.
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Skelton, Claude Eugene II. "Mixed Control Moment Gyro and Momentum Wheel Attitude Control Strategies." Thesis, Virginia Tech, 2003. http://hdl.handle.net/10919/9677.
Full textAbstract:
Attitude control laws that use control moment gyros (CMGs) and momentum wheels are derived with nonlinear techniques. The control laws command the CMGs to provide rapid angular acceleration and the momentum wheels to reject tracking and initial condition errors. Numerical simulations of derived control laws are compared. A trend analysis is performed to examine the benefits of the derived controllers. We describe the design of a CMG built using commercial off-the-shelf (COTS) equipment. A mixed attitude control strategy is implemented on the spacecraft simulator at Virginia Tech.Master of Science
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Yao, Cheng-Thai, and 姚承泰. "Single Gyroid-Nanostructured Metals with Controlled Particle Size from Electroless Plating Using Double Gyroid-Forming Block Copolymer Template." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/49383830310915419463.
Full textAbstract:
碩士國立清華大學
化學工程學系
104
In this study, by taking advantage of the nucleation and growth control of templated electroless plating, a novel approach to fabricate metallic materials with single gyroid (SG) texture using polymer template with double gyroid (DG) texture is suggested. Nanoporous polystyrene (PS) with DG texture is prepared from the self-assembly of polystyrene-b-poly(L-lactide) (PS-PLLA) followed by hydrolysis of PLLA block, and then used as a template for templated electroless plating. With pore-filling of the dilute Pd solution to the PS template, homogeneously distributed Pd clusters within the PS template can be prepared by using hydrazine for the reduction of Pd ions, giving one single Pd nuclei for the growth of SG-structured Ni. Subsequently, the Ni deposition using the Pd nuclei as catalytic site can be carried out to form SG-structured Ni. Finally, nanoporous Ni with SG-structured texture can be obtained after removal of the PS template by washing with dichloromethane. With the novel approach, SG-structured Ni with controlled particle radius from hundreds nm to micrometer can be prepared by tuning the growth time for the Ni deposition. Furthermore, tunable lattice constant of the SG-structured Ni and the corresponding filling ratio of the nanoporous Ni can be created from the pre-synthesized PS template with different molecular weights and compositions. To effectively achieve versatile purposes for optical applications, SG-structured Au is synthesized via the novel method as described above. As a result, this approach develop a platform technology to fabricate SG-structured metallic nanomaterials with versatile characteristic for novel properties from the nucleation and growth of templated electroless plating using self-assembled DG-structured block copolymers (BCPs) as templates.
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Hu, Po-Kai, and 胡博凱. "Flexible Photopatterned Reflectors by Gyroid Photonic Crystals." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/sa8jhg.
Full textAbstract:
碩士國立中山大學
材料與光電科學學系研究所
107
Photonic crystals made by self-assembly of block copolymers have been drawn much attention due to their great flexibility, high sensitivity as well as good compatibility with photopatterning methods. Here, the gyroid-structured block copolymer (BCP) thin films are fabricated for 3-D photonic crystals. With trapping of the structural coloration (TOSC), visible reflectance wavelengths can be manufactured using the block copolymer thin film. Moreover, tunable photonic bandgaps with scalable reflectance wavelengths can be successfully carried out by chemical adjustment of block copolymer chains. Therefore, the shifting of reflectance wavelength is observed by chemical adjustment after TOSC. With this technique, it is potential to be utilized in the production of a 3-D gyroid BCP photonic crystal film featuring various reflectance colors simultaneously.
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Chang, Chien Lung-Yu, and 張簡隆宇. "Study of polarization-dependent properties in gyroid photonic crystals." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/42264655734014596396.
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Silva, Catarina Maia Moreira da. "3D Printing of Gyroid Structures for Superior Structural Behaviour." Master's thesis, 2019. https://hdl.handle.net/10216/122072.
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Khabiboulline, Emil Timergalievich. "Angle-Resolved Mid-Infrared Spectroscopy of Gyroid Photonic Crystals." Thesis, 2016.
Find full textAbstract:
Gyroid photonic crystals, which can form photonic topological insulators, offer a rich
diversity of physics for fundamental study, in addition to yielding useful applications.
Understanding their band structure is crucial towards advancing both fronts. An
angle-resolved spectroscopy apparatus is constructed to experimentally measure
band structures. Operating at wavelengths from 7.7 to 11.1 μm, it is employed to
study single and double-gyroid photonic crystals, constructed of amorphous silicon
in 5 μm unit cells. Transmittance and reflectance act as indicators of density of
states, and are collected as spectra over angles of incidence ranging from 17 to 30
degrees. Comparison to theory confirms interesting features, such as bandgaps.
Further simulation guides the design of a crystal amenable to the first experimental
measurement of Weyl points at mid-infrared wavelengths.
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凌顗鈞. "Surface Plasmon Resonance and Photonic Band Structure of Gyroid Metamaterials." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/53710393195728370176.
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Lin, Zheng-Ying, and 林政穎. "Band Structure and Mode Analysis of Metal/Dielectric Double Gyroid." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/329z9c.
Full textAbstract:
碩士國立清華大學
光電工程研究所
105
Gyroid is a type of three-dimensional chiral structure that has been found in many insect species. Due to the periodic and chiral structure, the gyroid has been shown to exhibit photonic band gap and circular polarization dependent characteristics. Previous results show that the optical properties of the double gyroid can be tuned by refractive index contrast of the constituent materials or the volume fraction. However, double gyroid structures are mainly studied based on one constituent material, either dielectric or metal. The influence of different materials on the optical properties of double gyroid has not been explored. In this work, we investigate the polarization-dependent characteristics of a hybrid metal/dielectric double gyroid based on finite-difference time domain (FDTD) method. The corresponding band structure, transmission spectra, CD indices and coupling indices are calculated to examine the existence of polarization band gap and complete band gap in a metal/dielectric double gyroid. The evolution of band gaps with respect to different fractions of the hybrid system are presented. Furthermore, the dispersion surfaces and equifrequency contours (EFCs) are analyzed in the hybrid double gyroid. Based on the dispersion characteristics, anomalous guiding characteristics including negative refraction and collimation effect are discussed. These results could be of great interests for the design of function of circular-polarization devices based on hybrid metal/dielectric double gyroid structures.
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Juan, Yen-Ting, and 阮彥婷. "Gyroid-Forming Block Copolymer Self-Assembly in A 3D Confinement." Thesis, 2019. http://ndltd.ncl.edu.tw/cgi-bin/gs32/gsweb.cgi/login?o=dnclcdr&s=id=%22107NCHU5159064%22.&searchmode=basic.
Full textAbstract:
碩士國立中興大學
材料科學與工程學系所
107
Block copolymers (BCP) can self-assemble to form defined morphologies at nanometer scales, making them ideal materials for various applications. The self-assembly of BCPs is mainly controlled by the monomer–monomer interactions, block compositions, and molecular architectures. In addition, placing BCPs under confinement attracts people’s attention because of their diversity of self-assembled morphologies. Here we will use cylinder-forming and gyroid-forming PS-PLLA BCPs as a model system to study their self-assembly behaviors under 3D confinement. In the beginning, inverse opals from PS colloids synthesized by emulsifier free emulsion polymerization will be served as a 3D confinement. PUA (Polyurethane-acrylate) and SiO2 inverse opals are fabricated to be polymeric and ceramic 3D confinement structure, respectively. Different control parameters including pore size and hydrophilic property of template and volume fraction of block copolymer will be studied. After hydrolyzing PLLA block, ordered hierarchical structures with high surface areas and self-supporting properties would be fabricated and can be of great potentials for applications such as filter membrane.
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Wu, Yi-Hsiu, and 吳易修. "Controlled Ordering of Block Copolymer Gyroid Thin Films by Solvent Evaporation." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/26020224739479869952.
Full textAbstract:
碩士國立清華大學
化學工程學系
102
The fabrication of nanostructured thin films from the self-assembly of degradable block copolymers (BCPs) has attracted extensive attention in the past decade, and a variety of appealing applications in different research areas have been suggested by using the nanostructured thin films. To create useful BCP thin films for practical uses, controlled ordering of self-assembled nanostructures is essential. In this study, we aim to fabricate gyroid-forming thin films with controlled orientation through different solvent evaporation rates after solvent swelling a degradable BCP, polystyrene-block-poly(L-lactide) (PS-PLLA), thin film. The morphological evolution during solvent evaporation is examined, and interesting phase transitions from disorder to parallel cylinder and then perpendicular cylinder, finally gyroid can be found while using a partially selective solvent for PS to swell the PS-PLLA thin film. Moreover, during transitions, characteristic crystallographic plane of (111)G, (110)G and (211)G of the gyroid-forming thin film parallel to the air surface can be observed, and will gradually transform into the (110)G and (211)G co-existing planes, and finally transform to (211)G plane due to the preferential segregation of one block to the surface that affects the relative amount of each component on the air surface. Moreover, the phase transitions during evaporation are dependent upon the evaporation rate; by decreasing the evaporation rate, the parallel cylinders will transform directly to (211)G without the transitions to perpendicular cylinder phase and co-exist crystallographic planes of the gyroid. Although controlled solvent evaporation is a facile approach to prepare gyroid-forming thin films, the fabrication of long-range nanostructured thin films remains challenging. It is critical to increase the grain size of gyroid-forming thin film with controlled orientation. Herein, we aim to suggest a strategy for ordering the gyroid-forming thin films with large-size monograin by using PS stabilized Au nanoparticles addressing onto the thin film through solvent swelling followed by evaporation. With the introduction of the nanoparticles, the energy barrier for the nucleation of microphase separation is largely reduced and the growth of large-size monograin might be initiated from the nanoparticles resulting from the control of the nucleation density (the amount of nanoparticles introduced).
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Guariento, Lorenzo. "Design automation of lattice-based customized orthopedic for load-bearing implants." Doctoral thesis, 2022. http://hdl.handle.net/2158/1264388.
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