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1
Chinneck, Robert. "An automated welding system with 6 degrees of freedom." Thesis, University of Liverpool, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.397385.
Повний текст джерела
2
Moreu, Gamazo Jaime. "A kinematic coupling based 6 degrees of freedom dynamometer." Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/55278.
Повний текст джерелаАнотація:
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2009.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 130-131).
A new 6-degree of freedom dynamometer is presented. Six load cells measure the normal forces at the contact points of a three groove kinematic coupling. Three toggle clamps are used to preload the machine, so that it does not come apart. The device was designed, analyzed, built and tested. The error will mainly depend on frictional forces, load cells error and the toggle clamps. Frictional forces affect hysteresis, absorption and settlement of the coupling. Different solutions have been designed and tested to reduce friction. First, we tried direct contact between three stainless-steel rods and the stainless-steel load cells. The results were fully distorted due to the high friction of hard steel. We also tried three stainless-steels rods with flexures to contact the steel button cells. The results were much better and more repeatable, but absorption was not good enough. Finally, we tried using Teflon. Teflon is stuck to a steel plate that touches the contact points, leaving Teflon free of high stresses and allowing it to reduce friction between the contacts. The outcome was acceptable. In this case, hysteresis will be reasonably low, absorption is moderate and settlement-based problems are small for small preloads. Fortunately, settlement ability will be improved thanks to vibrations. Future investigations shall look towards low friction solutions, since the sturdiest and most user-friendly design will be the one that minimizes friction during the settlement process.
by Jaime Moreu Gamazo.
S.M.
3
Sepp, Wolfgang. "Visual servoing of textured free-form objects in 6 degrees of freedom." kostenfrei, 2008. http://mediatum2.ub.tum.de/node?id=646233.
Повний текст джерела
4
Snyder, Mark. "NONLINEAR STABILIZATION AND CONTROL OF MEDIUM RANGE SURFACE TO AIR INTERCEPTOR MISSILES." Master's thesis, University of Central Florida, 2009. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4081.
Повний текст джерелаАнотація:
Nonlinear stabilization and control autopilots are capable of sustaining nominal performance throughout the entire fight envelope an interceptor missile may encounter during hostile engagements and require no gain scheduling to maintain autopilot stability. Due to non minimum phase conditions characteristic of tail controlled missile airframes, a separation of time scales within the dynamic equations of motion between rotational and translational differential equations was enforced to overcome unstable effects of non minimum phase. Dynamic inversion techniques are then applied to derive linearizing equations which, when injected forward into the plant result in a fully controllable linear system. Objectives of the two time scale control architecture are to stabilize vehicle rotational rates while at the same time controlling acceleration within the lateral plane of the vehicle under rapidly increasing dynamic pressure. Full 6 degree of freedom dynamic terms including all coriolis accelerations due to translational and rotational dynamic coupling have been taken into account in the inversion process. The result is a very stable, nonlinear autopilot with fixed control gains fully capable of stable nonlinear missile control. Several actuator systems were also designed to explore the destabilizing effects second order nonlinear actuator characteristics can have on nonlinear autopilot designs.M.S.E.E.
School of Electrical Engineering and Computer Science
Engineering and Computer Science
Electrical Engineering MSEE
5
Baker, Antoin Lenard. "Analysis of three degree of freedom 6 x 6 tensegrity platform." [Gainesville, Fla.] : University of Florida, 2005. http://purl.fcla.edu/fcla/etd/UFE0010499.
Повний текст джерела
6
FERNANDEZ, MANUEL EDUARDO LOAIZA. "IMPLEMENTATION OF AN OPTICAL TRACKING DEVICE WITH 6 DEGREES OF FREEDOM FOR INTERACTING WITH VIRTUAL REALITY APPLICATIONS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2005. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=6664@1.
Повний текст джерелаАнотація:
COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOROs sistemas de rastreamento são uma das tecnologias cruciais para os sistemas de realidade virtual. Eles permitem detectar continuamente a posição e orientação de marcadores ou objetos específicos que o usuário utiliza para interagir com o sistema. Uma das tecnologias mais utilizadas para implementar este tipo de sistema é o rastreamento óptico, a qual permite ao usuário ter maior liberdade em seus movimentos porque não precisa de cabos ou elementos mecânicos que possam restringir ou atrapalhar a sensação de imersão que se tenta criar na interação com ambientes de realidade virtual. Este trabalho apresenta a construção e implementação de um dispositivo de entrada, baseado em rastreamento óptico, que é utilizado para interação com aplicações de realidade virtual do tipo semi-imersivas em um ambiente desktop comum. O dispositivo tem a capacidade de recuperar seis graus de liberdade dos movimentos feitos por um conjunto de marcadores que são controlados pela mão do usuário. A partir da recuperação dos seis graus de liberdade, o dispositivo é complementado com a capacidade de emissão de eventos que permitem a interação do usuário com a aplicação. No final apresenta-se uma aplicação que demonstra a adaptação dos eventos gerados e o desempenho do dispositivo implementado.
Tracking systems are a fundamental technology in virtual reality systems. They provide a continuous detection of the position and orientation of markers or specific objects that the user employs to interact with the system. One of the technologies most commonly used to implement these types of systems is the optical tracking, which allows the users to have more freedom in their movements because it does not need cables or mechanical elements that can restrict or hinder the immersion sensation that is tried to create in the interaction with virtual reality environments. This work presents the construction and implementation of an input device that is based on optical tracking that is used for interaction with semiimmersive virtual reality applications on ordinary desktop environments. This device has the capability to get the six degrees of freedom of the movements made by a set of markers that are controlled by the user hand. Based on the six degrees of freedom recovered, the device is complemented with the ability to emit events that allow the interaction of the user with the application. Finally, an application is presented for demonstrating the use of the generated events and the performance of our device.
7
Lin, Christie. "Linear regression analysis of 2D projection image data of 6 degrees-of-freedom transformed 3D image sets for stereotactic radiation therapy." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/76969.
Повний текст джерелаАнотація:
Thesis (S.M. and S.B.)--Massachusetts Institute of Technology, Dept. of Nuclear Science and Engineering, 2012.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 104-106).
Patient positioning is crucial to accurate dose delivery during radiation therapy to ensure the proper localization of dose to the target tumor volume. In patient positioning for stereotactic radiation therapy treatment, classical image registration methods are computationally costly and imprecise. We developed an automatic, fast, and robust 2D-3D registration method to improve accuracy and speed of identifying 6 degrees-of-freedom (DoF) transformations during patient positioning for stereotactic radiotherapy by creating a model of characteristic shape distributions to determine the linear relationship between two real-time orthogonal 2D projection images and the 3D volume image. We defined a preprocessed sparse base set of shape distributions that characterize 2D digitally reconstructed radiograph (DRR) images from a range of independent transformations of the volume. The algorithm calculates the 6-DoF transformation of the patient based upon two orthogonal real-time 2D images by correlating the images against the base set The algorithm has positioning accuracy to at least 1 pixel, equivalent to 0.5098 mm accuracy given this image resolution. The shape distribution of each 2D image is created in MATLAB in an average of 0.017 s. The online algorithm allows for rapid and accurate position matching of the images, providing the transformation needed to align the patient on average in 0.5276 s. The shape distribution algorithm affords speed, robustness, and accuracy of patient positioning during stereotactic radiotherapy treatment for small-order 6-DoF transformations as compared with existing techniques for the quantification of patient setup where both linear and rotational deviations occur. This algorithm also indicates the potential for rapid, high precision patient positioning from the interpolation and extrapolation of the linear relationships based upon shape distributions. Key words: shape distribution, image registration, patient positioning, radiation therapy
by Christie Lin.
S.M.and S.B.
8
Gu, Jie. "Development of a 6-degree-of-freedom magnetically levitated instrument with nanometer precision." Thesis, Texas A&M University, 2003. http://hdl.handle.net/1969/118.
Повний текст джерела
9
Ögren, Jim. "Simulation of a Self-bearing Cone-shaped Lorentz-type Electrical Machine." Thesis, Uppsala universitet, Elektricitetslära, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-202443.
Повний текст джерелаАнотація:
Self-bearing machines for kinetic energy storage have the advantage of integrating the magnetic bearing in the stator/rotor configuration, which reduces the number of mechanical components needed compared with using separated active magnetic bearings. This master's thesis focus on building a MATLAB/Simulink simulation model for a self-bearing cone-shaped Lorenz-type electrical machine. The concept has already been verified analytically but no dynamic simulations have been made. The system was modeled as a negative feedback system with PID controllers to balance the rotor. Disturbances as signal noise, external forces and torques were added to the system to estimate system robustness. Simulations showed stability and promising dynamics, the next step would be to build a prototype.
10
Calhoun, Sean M. "Six Degree-of-Freedom Modeling of an Uninhabited Aerial Vehicle." Ohio University / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1149543622.
Повний текст джерела
11
Hu, Tiejun. "Design and control of a 6-Degree-of-Freedom levitated positioner with high precision." Diss., Texas A&M University, 2005. http://hdl.handle.net/1969.1/2360.
Повний текст джерелаАнотація:
This dissertation presents a high-precision positioner with a novel superimposed
concentrated-field permanent-magnet matrix. This extended-range multi-axis positioner can
generate all 6-DOF (degree-of-freedom) motions with only a single moving part. It is actuated
by three planar levitation motors, which are attached on the bottom of the moving part. Three
aerostatic bearings are used to provide the suspension force against the gravity for the system.
The dynamic model of the system is developed and analyzed. And several control techniques
including SISO (single input and single output) and MIMO (multi inputs and multi outputs)
controls are discussed in the dissertation. The positioner demonstrates a position resolution of 20
nm and position noise of 10 nm rms in x and y and 15 nm rms in z. The angular resolution
around the x-, y-, and z-axes is in sub-microradian order. The planar travel range is 160 mm ??
160 mm, and the maximum velocity achieved is 0.5 m/s at a 5-m/s2 acceleration, which can
enhance the throughput in precision manufacturing. Various experimental results are presented in
this dissertation to demonstrate the positioner??s capability of accurately tracking any planar
trajectories. Those experimental results verified the potential utility of this 6-DOF high-precision
positioner in precision manufacturing and factory automation.
12
Masliah, Maurice R. "Measuring the allocation of control in 6 degree of freedom human-computer interaction tasks." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/NQ63712.pdf.
Повний текст джерела
13
Gurbuz, Sarper. "Design And Construction Of A Six Degree Of Freedom Platform." Master's thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/12607806/index.pdf.
Повний текст джерелаАнотація:
ABSTRACT
DESIGN AND CONSTRUCTION OF A
SIX DEGREE OF PLATFORM
Gürbü
z, Sarper M.S., Department of Mechanical Engineering Supervisor: Prof. Dr. Tuna BALKAN Co-Supervisor: Prof. Dr. M. A. Sahir ARIKAN November 2006, 83 pages In this thesis a six degree of freedom (DOF) parallel manipulator is designed, developed and simulated virtually. The platform, which is specified and focused on in this thesis, is the specific solution for the generating the required data to simulate a land, airborne or sea vehicle&
#8217
s motion trajectory in the laboratory environment. After explaining the need for such platforms for the military industry, the existing devices will be presented and discussed. Then the design period will be explained while pointing out the key performance criteria. The gathered performance values of the first design iteration will be presented and the modifications done in order to get to the expected performance will be given. Finally an investigation, in order to find the maximum payload that the platform can handle, is performed and presented. It is too hard to get to the desired performance values in mechanical design and manufacturing without using the CAD (Computer Aided Design) and CAM (Computer Aided Manufacturing) programs. In this thesis ProEngineer Wildfire®
is used for solid modeling the components, the sub-assemblies and the final assembly, ANSYS Workbench®
is used for investigating the modal behavior of the components, ADAMS®
2003 is used for the dynamic simulation of the mechanism, ADAMS/Flex®
, ADAMS/AutoFlex®
and ADAMS/Durability®
are used to analyze the results when flexibility is embedded into the system. At the end of the thesis in Appendix section five technical drawings with the nominal dimensions are given in order to clarify the construction period. By the regulations that must be obeyed in ASELSAN only the nominal dimensions are given in the technical drawings. All the dimensional and geometrical tolerances are given in the approved technical drawings that are proprietary of ASELSAN. Keywords: 6-Axis Motion Platform, Application of CAD and analysis programs, Electromechanical Design, Stewart Platform
14
Yu, Ho. "Controller design and implementation for a 6-degree-of-freedom magnetically levitated positioner with high precision." Thesis, Texas A&M University, 2005. http://hdl.handle.net/1969.1/2603.
Повний текст джерелаАнотація:
This thesis presents the controller design and implementation of a high-precision 6-degree-of-freedom (6-DOF) magnetically levitated (maglev) positioner. This high-precision positioning system consists of a novel concentrated-field magnet matrix and a triangular single-moving part that carries three 3-phase permanent-magnet linear-levitation-motor armatures. Since only a single levitated moving part, namely the platen, generates all required fine and coarse motions, this positioning system is reliable and low-cost. Three planar levitation motors based on the Lorentz-force law not only generate the vertical force to levitate the triangular platen but control the platen??s position and orientation in the horizontal plane. All 6-DOF motions are controlled by magnetic forces only. The platen is regarded a pure mass system, and the spring and damping coefficients are neglected except for the vertical directions. Single-input single-output (SISO) digital lead-lag controllers are designed and implemented on a digital signal processor (DSP). This 6-DOF fully magnetically levitated positioner has a total mass of 5.91 kg and currently exhibits a 120 mm ?? 120 mm travel range. This positioner is highly suitable for semiconductor-manufacturing applications such as wafer steppers. Several experimental motion profiles are presented to demonstrate the maglev stage??s capability of accurately tracking any planar and 3-D paths.
15
Henson, Peter MA. "Development of a 6 degree-of-freedom manipulator arm for use on an urban search and rescue robot." Master's thesis, University of Cape Town, 2012. http://hdl.handle.net/11427/12277.
Повний текст джерелаАнотація:
Includes abstract.Includes bibliographical references.
This document reports on the design, construction and testing of the manipulator arm that is to be fitted to UCT's Urban Search and Rescue Robot (USRR), named the Ratel. The 6 degree-of-freedom manipulator arm is mounted on the crawler base. The USRR is designed to traverse difficult terrain in search of survivors. The base is therefore equipped with variable geometry tracks to enable it to traverse stairs and other tricky terrain. The sensor payload is equipped with life detection equipment and the manipulator arm enables the USRR to manipulate with its environment (opening doors etc.) and to interact with survivors, passing them water or food packs.
16
Bates, Nathaniel A. "Investigation of Anterior Cruciate Ligament and Medial Collateral Ligament Biomechanics during 6-Degree-of-Freedom, Robotically-Simulated Athletic Tasks." University of Cincinnati / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1406819977.
Повний текст джерела
17
Tabia, Ahmed. "Pose estimation with event camera." Electronic Thesis or Diss., université Paris-Saclay, 2024. http://www.theses.fr/2024UPAST093.
Повний текст джерелаАнотація:
La pose de la caméra est utilisée pour décrire la position et l'orientation d'une caméra dans un système de coordonnées absolu, en référence à six degrés de liberté. L'estimation de la pose de la caméra est essentielle dans divers domaines d'application, tels que la réalité augmentée, la navigationrobotique et les véhicules autonomes.Ces domaines exploitent la pose de la caméra pour des calculs ultérieurs, comme la localisation des objets et la perception de la scène.Estimer la pose d'une caméra présente des défis dans différents scénarios ; les conditions d'éclairage médiocres, y compris une obscurité ou une luminosité extrêmes, limitent l'efficacité de la plupart des méthodes basées sur des caractéristiques. Ces conditions d'éclairage défavorablesentravent la détection et la correspondance précises des caractéristiques, affectant ainsi la précision de l'estimation de la pose de la caméra.Les scènes manquant de textures distinctes compliquent l'extraction de points clés significatifs, tandis que le mouvement rapide entraîne un flou cinétique, nuisant à la qualité de l'image et à la précision de l'estimation de la pose.La plupart de ces défis rencontrés dans l'estimation de la pose de la caméra sont largement liés à la nature des caméras traditionnelles, qui capturent le monde sous forme d'une série d'images fixes, prises successivement à un rythme rapide. Dans les cas où ces difficultés sont particulièrement prononcées, les caméras événementielles offrent des avantages potentiels.Les caméras événementielles sont des capteurs bio-inspirés qui imitent le fonctionnement de la rétine humaine, en capturant les changements d'intensité des pixels plutôt que d'enregistrer des images complètes à un taux fixe, comme le font les caméras traditionnelles basées sur des trames.Cette thèse se concentre sur l'estimation de la pose des caméras événementielles et vise à explorer l'application de méthodes d'apprentissage en profondeur pour la pose et la relocalisation basées sur ces caméras, en tirant parti de leurs propriétés uniques telles que la haute résolution temporelle, la faible latence et la large plage dynamique.La thèse apporte plusieurs contributions au domaine de l'estimation de la pose de caméra événementielle en utilisant des techniques d'apprentissage profond. Ces contributions peuvent être résumées comme suit :• La thèse fournit un aperçu complet des informations de base et des travaux connexes, établissant ainsi une base solide et une compréhension contextuelle de l'estimation de la pose de caméra événementielle.• La thèse explore et développe des approches spécialisées d'apprentissage profond adaptées à l'estimation de la pose de caméra événementielle. Ces techniques exploitent la puissance de l'apprentissage profond pour estimer avec précision la pose de la caméra à l'aide dedonnées événementielles.• La thèse introduit des méthodes pour projeter les données événementielles en données semblables à des images, facilitant l'application d'approches dédiées d'apprentissage profond. Ce processus de projection permet une utilisation efficace des informations événementielles dans la tâche d'estimation de la pose de la caméra.• La thèse propose une nouvelle approche qui applique directement des techniques d'apprentissage profond aux données événementielles brutes, les traitant comme un nuage de points plutôt que de les convertir en images. Cette approche exploite l'ensemble des informations capturées par la caméra événementielle et permet un processus d'apprentissage de bout en boutCamera pose is used to describe the position and orientation of a camera in an absolute coordinate system, with reference to six degrees of freedom. Estimating the camera pose is essential in various application domains, such as augmented reality, robotic navigation, and autonomous vehicles.These fields rely on camera pose for subsequent calculations, such as object localization and scene perception.Estimating the pose of a camera presents challenges in different scenarios; poor lighting conditions, including extreme darkness or brightness, limit the effectiveness of most feature-based methods. These unfavorable lighting conditions hinder precise feature detection and matching, thereby affecting the accuracy of camera pose estimation. Scenes lacking distinct textures complicate the extraction of meaningful keypoints, while rapid motion leads to motion blur, affecting image quality and pose estimation accuracy.Most of these challenges encountered in camera pose estimation are largely related to the nature of traditional cameras, which capture the world as a series of static images taken successively at a rapid pace. In cases where these difficulties are particularly pronounced, event-based cameras offer potential advantages.Event-based cameras are bio-inspired sensors that mimic the functioning of the human retina, capturing changes in pixel intensity rather than recording full images at a fixed rate, as traditional frame-based cameras do.This thesis focuses on estimating the pose of event-based cameras and aims to explore the application of deep learning methods for pose estimation and relocalization based on these cameras, leveraging their unique properties such as high temporal resolution, low latency, and wide dynamic range.The thesis makes several contributions to the field of event-based camera pose estimation using deep learning techniques. These contributions can be summarized as follows:• The thesis provides a comprehensive overview of foundational information and related work, thus establishing a solid foundation and contextual understanding of event-based camera pose estimation.• The thesis explores and develops specialized deep learning approachestailored to event-based camera pose estimation. These techniques harness the power of deep learning to accurately estimate camera pose using event data.• The thesis introduces methods to project event data into image-like data, facilitating the application of dedicated deep learning approaches.This projection process allows for efficient use of event data in the camera pose estimation task.• The thesis proposes a novel approach that directly applies deep learning techniques to raw event data, treating them as a point cloud rather than converting them into images. This approach leverages the entirety of information captured by the event-based camera and enables an end-to-end learning process
18
Miranda, Ricardo E. "Development of a nonlinear 6-degree of freedom miniature rotary-wing unmanned aerial vehicle software model and PID flight path controller using Mathworks Simulink simulation environment." Thesis, Monterey, California : Naval Postgraduate School, 2009. http://edocs.nps.edu/npspubs/scholarly/theses/2009/Sep/09Sep%5FMiranda.pdf.
Повний текст джерелаАнотація:
Thesis (M.S. in Electrical Engineering)--Naval Postgraduate School, September 2009.Thesis Advisor(s): Hutchins, Robert G. ; Dobrokhodov, Vladimir ; Kitsios, Ioannis. "September 2009." Description based on title screen as viewed on November 5, 2009. Author(s) subject terms: Hardware in the Loop (HIL), Software in the Loop (SIL) Simulation Environment, 6-Degree of Freedom (6-DOF) Rotary-wing Unmanned Aerial Vehicle (RW UAV) model , PID Flight Path Controllers Includes bibliographical references (p. 111). Also available in print.
19
Ahmed, Abu Hanieh. "Multi degrees of freedom vibration isolation." Doctoral thesis, Universite Libre de Bruxelles, 2001. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/211553.
Повний текст джерела
20
Pollmann, Frank. "Charge degrees of freedom on frustrated lattices." [S.l.] : [s.n.], 2006. http://deposit.ddb.de/cgi-bin/dokserv?idn=982205066.
Повний текст джерела
21
Jong, Boudewijn Ruben de. "A six degrees of freedom MEMS manipulator." Enschede : University of Twente [Host], 2006. http://doc.utwente.nl/57599.
Повний текст джерела
22
Borade, Shashibhushan Prataprao 1981. "Maximizing degrees of freedom in wireless networks." Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/16692.
Повний текст джерелаАнотація:
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2004.Includes bibliographical references (p. 61-63).
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
We consider communication from a single source to a single destination in a wireless network with fading. Both source and destination have multiple antennas. The information reaches the destination through a sequence of layers of single-antenna relays. A non-separation-based strategy is proposed and shown to achieve a rate equal to the capacity of a point-to-point multiantenna system in the high SNR regime. This implies that lack of coordination between relay nodes does not reduce the achievable rate at high SNR. We then derive the tradeoffs between network size and rate. We also derive the rate-diversity tradeoff for this network and study how it is affected by the network size. This shows that increasing network size is much more difficult when the codelength does not span a large number of fading realizations. Finally some implications to ad-hoc networks are discussed.
by Shashibhushan Prataprao Borade.
S.M.
23
O'Brien, Aroon. "Charge degrees of freedom on the kagome lattice." Doctoral thesis, Universitätsbibliothek Chemnitz, 2011. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-71860.
Повний текст джерелаАнотація:
Within condensed matter physics, systems with strong electronic correlations give rise to fascinating phenomena which characteristically require a physical description beyond a one-electron theory, such as high temperature superconductivity, or Mott metal-insulator transitions. In this thesis, a class of strongly correlated electron systems is considered. These systems exhibit fractionally charged excitations with charge +e/2 or -e/2 in two dimensions (2D) and three dimensions (3D), a consequence of both strong correlations and the geometrical frustration of the interactions on the underlying lattices.
Such geometrically frustrated systems are typically characterized by a high density of low-lying excitations, leading to various interesting physical effects. This thesis constitutes a study of a model of spinless fermions on the geometrically frustrated kagome lattice. Focus is given in particular to the regime in which nearest-neighbour repulsions V are large in comparison with hopping t between neighbouring sites, the regime in which excitations with fractional charge occur.
In the classical limit t = 0, the geometric frustration results in a macroscopically large ground-state degeneracy. This degeneracy is lifted by quantum fluctuations. A low-energy effective Hamiltonian is derived for the spinless fermion model for the case of 1/3 filling in the regime where |t| << V . In this limit, the effective Hamiltonian is given by ring-exchange of order ~ t^3/V^2, lifting the degeneracy. The effective model is shown to be equivalent to a corresponding hard-core bosonic model due to a gauge invariance which removes the fermionic sign problem. The model is furthermore mapped directly to a Quantum Dimer model on the hexagonal lattice. Through the mapping it is determined that the kagome lattice model exhibits plaquette order in the ground state and also that fractional charges within the model are linearly confined.
Subsequently a doped version of the effective model is studied, for the case where exactly one spinless fermion is added or subtracted from the system at 1/3 filling. The sign of the newly introduced hopping term is shown to be removable due to a gauge invariance for the case of hole doping. This gauge invariance is a direct result of the bipartite nature of the hole hopping and is confirmed numerically in spectral density calculations. For further understanding of the low-energy physics, a derivation of the model gauge field theory is presented and discussed in relation to the confining quantum electrodynamic in two dimensions.
Exact diagonalization calculations illustrate the nature of the fractional charge confinement in terms of the string tension between a bound pair of defects. The calculations employ topological symmetries that exist for the manifold of ground-state configurations.
Dynamical calculations of the spectral densities are considered for the full spinless fermion Hamiltonian and compared in the strongly correlated regime with the doped effective Hamiltonian. Calculations for the effective Hamiltonian are then presented for the strongly correlated regime where |t| << V .
In the limit g << |t|, the fractional charges are shown to be effectively free in the context of the finite clusters studied. Prominent features of the spectral densities at the Gamma point for the hole and particle contributions are attributed to approximate eigenfunctions of the spinless fermion Hamiltonian in this limit. This is confirmed through an analytical derivation. The case of g ~ t is then considered, as in this case the confinement of the fractional charges is observable in the spectral densities calculated for finite clusters. The bound states for the effectively confined defect pair are qualitatively estimated through the solution of the time-independent Schroedinger equation for a potential which scales linearly with g. The double-peaked feature of spectral density calculations over a range of g values can thus be interpreted as a signature of the confinement of the fractionally charged defect pair.
Furthermore, the metal-insulator transition for the effective Hamiltonian is studied for both t > 0 and t < 0. Exact diagonalization calculations are found to be consistent with the predictions of the effective model. Further calculations confirm that the sign of t is rendered inconsequential due to the gauge invariance for g in the regime |t| << V . The charge-order melting metal-insulator transition is studied through density-matrix renormalization group calculations. The opening of the energy gap is found to differ for the two signs of t, reflecting the difference in the band structure at the Fermi level in each case. The qualitative nature of transition in each case is discussed.
As a step towards a realization of the model in experiment, density-density correlation functions are introduced and such a calculation is shown for the plaquette phase for the effective model Hamiltonian at 1/3 filling in the absence of defects. Finally, the open problem of statistics of the fractional charges is discussed.
24
Mattingly, Sean Walter. "Velocity Space Degrees of Freedom of Plasma Fluctuations." Thesis, The University of Iowa, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10263114.
Повний текст джерелаАнотація:
This thesis demonstrates a measurement of a plasma fluctuation velocity-space cross-correlation matrix using laser induced fluorescence. The plasma fluctuation eigenmode structure on the ion velocity distribution function can be empirically determined through singular value decomposition from this measurement. This decomposition also gives the relative strengths of the modes as a function of frequency. Symmetry properties of the matrix quantify systematic error. The relation between the eigenmodes and plasma kinetic fluctuation modes is explored. A generalized wave admittance is calculated for these eigenmodes. Since the measurement is a localized technique, it may be applied to plasmas in which a single point measurement is possible, multipoint measurements may be difficult, and a velocity sensitive measurement technique is available.
25
Cable, Hugo Vaughan. "Localising relational degrees of freedom in quantum mechanics." Thesis, Imperial College London, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.424451.
Повний текст джерела
26
Massimino, Michael James. "Teleoperator tracking performance in six degrees of freedom." Thesis, Massachusetts Institute of Technology, 1990. http://hdl.handle.net/1721.1/14063.
Повний текст джерелаАнотація:
Thesis (Mech. E.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1990.Title as it appears in the M.I.T. Graduate List, June 1990: Teleoperator tracking in six degrees of freedeom.
Includes bibliographical references (leaf 40).
by Michael James Massimino.
Mech.E.
27
Feagin, Aprell McQueeney. "“The Angular Degrees of Freedom” and Other Stories." Thesis, University of North Texas, 2014. https://digital.library.unt.edu/ark:/67531/metadc700030/.
Повний текст джерелаАнотація:
The preface, " Performing Brain Surgery: The Problematic Nature of Endings in Short Fiction," deals with the many and varied difficulties short story writers encounter when attempting to craft endings. Beginning with Raymond Carver and Flannery O’Connor and moving to my own work, I discuss some of the obscure criteria used to designate a successful ending, as well as the more concrete idea of the ending as a unifying element. Five short stories make up the remainder of this thesis: "In-between Girls," "Crocodile Man," "Surprising Things, Sometimes Amusing," "Good Jewelry," and "The Angular Degrees of Freedom."
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Mattingly, Sean Walter. "Velocity space degrees of freedom of plasma fluctuations." Diss., University of Iowa, 2017. https://ir.uiowa.edu/etd/5967.
Повний текст джерелаАнотація:
This thesis demonstrates a measurement of a plasma fluctuation velocity-space cross-correlation matrix using laser induced fluorescence. The plasma fluctuation eigenmode structure on the ion velocity distribution function can be empirically determined through singular value decomposition from this measurement. This decomposition also gives the relative strengths of the modes as a function of frequency. Symmetry properties of the matrix quantify systematic error. The relation between the eigenmodes and plasma kinetic fluctuation modes is explored. A generalized wave admittance is calculated for these eigenmodes. Since the measurement is a localized technique, it may be applied to plasmas in which a single point measurement is possible, multipoint measurements may be difficult, and a velocity sensitive measurement technique is available.
29
Rajagopal, Gunaretnam. "Systems of coupled quantum and classical degrees of freedom." Diss., Georgia Institute of Technology, 1991. http://hdl.handle.net/1853/30689.
Повний текст джерела
30
Ng'andu, Alvert Namasamu. "Estimation of rotational degrees of freedom using spline functions." Thesis, University of Nottingham, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.282786.
Повний текст джерела
31
Norell, Emil. "Gamma Knife treatment planning with new degrees of freedom." Thesis, KTH, Optimeringslära och systemteori, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-246149.
Повний текст джерелаАнотація:
The Leksell Gamma Knife® is an instrument designed for high precision treatment of tumours and lesions located in the brain and upper spine. Today, the radioactive cobalt-60 sources can only move linearly along the radiation unit, but the machine could be modified to include rotational motion as well. We extend an existing linear programming approach to inverse planning for the Gamma Knife by examining the benefits from rotational degrees of freedom. The improvements offered from rotations are limited, but easy to make use of. We investigate the model in four patient cases, and find that an upper bound on the improvement of the optimization cost function is between 4.5% and 7.0% depending on case. With a total of four angles distributed uniformly over a 45 degree interval, one can in each case achieve a solution that performs up to within 1% of this bound. The average maximal improvements in terms of clinical metrics are 0.5% selectivity and 1.9% gradient index, at the cost of 5.9% worse beam-on time. No statistically significant change in coverage is found. A dynamic model based on column generation is proposed, which allows treatment during constant velocity angular motion and can achieve practically the same plan quality as the model with uniformly distributed angles at a significantly lower problem size. A similar algorithm can be designed to locate the most effective angles in a non-uniform manner that achieves better plans with fewer added rotational degrees of freedom. Trade-offs between memory and solution times are used to successively reduce the RAM occupation by around 90% and make significantly larger models computationally feasible to solve. A voxel clustering approach with emphasis on surface voxels, adapted to the radiosurgical framework, can significantly reduce the problem size while still producing competitive plans.Strålkniven Leksell Gamma Knife® är ett instrument designat för högprecisionsbestrålning av tumörer och lesioner i hjärnan och övre delen av ryggraden. Idag kan de radioaktiva källorna endast förflyttas linjärt under behandlingen, men maskinen skulle kunna modifieras för att även tillåta rotationsrörelser. Vi utvidgar ett ramverk för inversplanering, formulerat som ett linjär-programmeringsproblem, genom att undersöka fördelarna med nya rotationsfrihetsgrader. Förbättringarna som rotationer möjliggör är begränsade, men kan relativt enkelt tas till vara. Vi undersöker de potentiella förändringarna i fyra patientfall och finner att den övre gränsen av förbättringarna för målfunktionsvärdet i optimeringsproblemet är mellan 4.5% och 7.0% beroende på fall. Genom att tillåta rotation av källorna till fyra jämnt fördelade vinklar över 45 grader kan man i samtliga fall hitta en lösning som är inom 1% från det bästa målfunktionsvärdet. De genomsnittliga förbättringarna i form av kliniska metriker är 0.5% selektivitet och 1.9% gradient-index, dock på bekostnad av en försämring av bestrålningstiden med 5.9%. Ingen tydlig förändring av täckningen kunde påvisas. En modell baserad på kolumngenerering, som tillåter behandling under rotation av kollimator-kroppen med konstant hastighet, föreslås. I denna modell kan praktiskt taget lika bra lösningar uppnås som för likformigt fördelade vinklar, men med betydligt mindre problemstorlek. En liknande algoritm kan lokalisera de mest effektiva vinklarna och åstadkomma samma plankvalitet med färre, men olikformt fördelade, rotationsfrihetsgrader. RAM-användningen kan reduceras med cirka 90% genom avvägningar mellan minne och beräknings-tider, vilket möjliggör lösning av probleminstanser som tidigare var beräkningsmässigt omöjliga. Klustringsmetoder av voxlar anpassade till strålkniven kan minska problemstorleken betydelsefullt medan de resulterande behandlingsplanerna är fortsatt konkurrenskraftiga.
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Williams, Mark E. (Mark Edd). "Precision six degrees of freedom magnetically-levitated photolithography stage." Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/9850.
Повний текст джерела
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Olsson, Henrik. "Utilizing the Degrees of Freedom in Radiation Therapy Optimization." Thesis, KTH, Optimeringslära och systemteori, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-214566.
Повний текст джерелаАнотація:
The development of advanced software for radiation therapy treatment has had a significant role in the last decades’ improvements in cancer treatment. By optimizing the radiation dose given to each patient, the probability of a successful treatment increases. The development of mathematical optimization methods, required to produce as good radiation therapy treatment plans as possible, is therefore of high importance. When producing treatment plans for Volumetric Modulated Arc Therapy (VMAT) today, there are degrees of freedom that are not fully utilized. The possibility of rotating the patient couch and collimator during radiation delivery, to achieve a better dose distribution over the patient, is not taken advantage of. In order to take full advantage of these extra degrees of freedom, methods for predicting how good different arcs will perform during VMAT-delivery need to be developed. Since the number of possible VMAT-arcs is very large, such a method needs to be very time efficient in order to be of conventional use. In this thesis, a heuristic method for finding good VMAT-arcs for patients with multiple brain metastasis is proposed. In the method, the sphere around the patient’s head is discretized into a number of beam directions. From each of these beam directions a projection of the patient’s anatomy is produced, and based on the relative location of the cancer metastasis and the organs desired to protect, a cost is assigned. By linking together adjacent beam direction, VMAT-arcs can be created, and each possible VMATarc is assigned an arc cost depending on the cost of the beam directions it traverses. Such arc cost is used as an indication of how good a VMAT-arc will perform during VMAT-delivery. The heuristic method is tested and evaluated on four different patient cases. In three of the patient cases, the proposed method gives good results. Overall the results indicate that it is possible to predict how good a VMAT-arc will perform during VMAT-delivery, by looking at the relative locations of the target and organ projections in a discrete number of points along the arc. However, since the number of test cases are few, no statistically significant conclusions can be drawn.Utvecklingen av avancerad mjukvara för strålningsterapi är en del av de senaste decenniernas framsteg inom cancerbehandling. Genom att optimera stråldosen som ges till varje patient ökar sannolikheten att behandlingen lyckas. Utvecklingen av matematiska optimeringsmetoder, som används för att producera så bra strålningsplaner som möjligt, är därför av högsta vikt. När man producerar strålningsplaner för VMAT (Volumetric Modulated Arc Therapy) idag, utnyttjas inte alla frihetsgrader. Möjligheten att rotera patientbritsen och kollimatorn för att leverera en bättre strålningsdos till patienten lämnas ute. För att kunna utnyttja dessa frigetsgrader fullt ut krävs utveckling av metoder som kan förutspå hur bra olika strålningstrajektorier är. Då det finns ett väldigt stort antal möjliga strålningstrajektorier måste dessa metoder vara tidseffektiva. Under detta exjobb har en heuristisk metod för att hitta bra VMAT-trajektorier för patienter med flera hjärnmetastaser utvecklats. I metoden discretiseras sfären runt patientens huvud i ett antal strålningsriktningar. Från varje strålningsriktning produceras en projektion av patientens anatomi. Baserat på de relativa positionerna av hjärnmetastaserna och de organ man vill skydda tilldelas varje strålningsriktning ett straff. Genom att binda samman intilliggande strålningsriktningar kan sedan VMAT-trajektorier produceras, och varje VMAT-trajektorie tilldelas ett straff baserat på straffen hos de strålningsriktningar som bundits samman för att bilda trajektorien. Straffet som tilldelats en trajektorie används sedan som en indikator för hur bra trajektorien är för VMAT-behandling. Den heuristiska metoden är testad i fyra olika patientfall. I tre av patientfallen ger metoden bra resultat. I sin helhet tyder resultaten på att det är möjligt att förutsäga hur bra en VMAT-trajektorie är för VMAT-behandling, genom att från ett par punkter längst trajektorien titta på de relativa positionerna av metastaserna och de organ som man vill skydda. Dock gör det låga antalet av testfall att inga statisktiskt säkerställda slutsatser kan dras.
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Tomasin, Marco. "Quantum information with polarization and temporal degrees of freedom." Doctoral thesis, Università degli studi di Padova, 2017. http://hdl.handle.net/11577/3423242.
Повний текст джерелаАнотація:
This work deals with creation, manipulation and detection of quantum photon states, in one and two degrees of freedom, encoded in polarization and time-bin basis. A particular quantum state, an entangled state, carries a wide range of implementations, that are impossible via classical tasks, such as teleportation, dense coding, and quantum communication protocols. One of these tasks, quantum cryptography, allows intrinsically secure transmission of information. Nowadays, quantum key distribution is implemented in intercity quantum networks, by using telecommunication fibers to connect nodes within the network. In future scenarios, photons could travel through greater distances, but, due to losses, fiber links need for quantum repeater, a very demanding engineering solution. An alternative way, is the use of free-space satellite quantum networks.
Here we focus on polarization and time bin degrees of freedom (DOFs) of the photons as a resource for quantum information. In particular we study the possibility to share an hyper-entangled state in polarization and time-bin DOFs between two spatially separated users. In addition we study a new tomographic method, based on compressed sensing, to recover the density matrix of a quantum state when prior information are available.
Typical implementation of time-bin photon source, based on Franson’s scheme, suffers on intrinsic loophole. To overcome that we experimentally demonstrated that with a time-bin source it is possible to obtain a very high visibility in order to violate a chained Bell inequality.
Interference at single photon level through satellite-ground channels is presented here, showing that, temporal encoding is preserved along turbulent channels. With this experiment we show that temporal encoding can be use for a future implementation of satellite quantum communication. Finally, to complete this work, we demonstrate a new method to certified the randomness of a source, useful in many task, such as quantum cryptography by using a polarization entangled photons source.Questo lavoro è incentrato sulla creazione, manipolazione e rivelazione di fotoni, in uno o due gradi di libertà, codificati nel dominio del tempo o della polarizzazione. L’entanglement quantistico può essere usato per una vasta gamma di applicazioni che non sono possibili classicamente, come il teletrasporto quantistico, il denscoding e la crittografia quantistica. Quest’ultima, fornisce un grado di sicurezza incondizionato, poichè basata su leggi fisiche. Attualmente, le reti di comunicazione quantistica sono state implementate a livello cittadino utilizzando fibre ottiche per le telecomunicazioni. In uno scenario futuro, sarà necessario raggiungere distanze maggiori, ma a causa delle alte perdite, soluzioni basate su link in fibra saranno difficili da implementare. Un’alternativa è quella di utilizzare reti satellitari per le comunicazioni quantistiche. In questo lavoro ci focalizziamo sulla realizzazione di una sorgente di fotoni hyper-entangled in tempo e polarizzazione. La particolarità di questa sorgente è la possibilità di condividere lo stato tra due utenti spazialmente separati. Inoltre, abbiamo sviluppato un algoritmo di tomografia quantistica basato sul compressed sensing, per la ricostruzione di uno stato con un numero molto limitato di misure. Per poter funzionare, questo algoritmo ha bisogno di informazioni sullo stato di partenza. Successivamente, vedremo come il loophole dovuto alla postselezione in una sorgente di fotoni entangled in time-bin, può essere superato con una buona implementazione del setup ottico. Infatti nel nostro esperimento è stato possibile raggiungere una visibilità molto elevata, che ha permesso di violare le disuguaglianze di Bell concatenate. Vedremo inoltre, la possibilità di utilizzare fotoni codificati nel dominio temporale in un canale satellite-terra. Infatti, abbiamo dimostrato che la turbolenza non rovina lo stato inviato, aprendo la strada a futuri sviluppi basati sulla codifica temporale. Infine, per completare questo lavoro, una sorgente di fotoni entangled in polarizzazione è stata utilizzata per dimostrare un nuovo metodo per la certificazione della randomicità di una sorgente.
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Planes, Conangla Gerard. "Levitation and control of particles with internal degrees of freedom." Doctoral thesis, Universitat Politècnica de Catalunya, 2020. http://hdl.handle.net/10803/669610.
Повний текст джерелаАнотація:
Levitodynamics is a fast growing field that studies the levitation and manipulation of micro- and nanoobjects, fuelled by both fundamental physics questions and technological applications. Due to the isolated nature of trapped particles, levitated systems are highly decoupled from the environment, and offer experimental possibilities that are absent in clamped nanomechanical oscillators. In particular, a central question in quantum physics is how the transition between the classical and quantum world materializes, and levitated objects represent a promising avenue to study this intermediate regime.
In the last years, most levitation experiments have been restricted to optically trapped silica nanoparticles in vacuum, controlling the particle's position with intensity modulated laser beams. However, the use of optical traps severely constrains the experiments that can be performed, because few particle materials can withstand the optical absorption and resulting heating in vacuum. This completely prevents the use of objects with internal degrees of freedom, which---coupled to mechanical variables---offer a clear path towards the study of quantum phenomena at the macroscale.
In this thesis, we address these issues by considering other types of trap and feedback schemes, achieving excellent control on the dynamics of optically active nanoparticles. With stochastic calculus, simulations and experiments, we study the dynamics of trapped particles in different regimes, considering also a hybrid quadrupole-optical trapping scheme. Then, using a Paul trap of our own design, we demonstrate the trapping, interrogation and feedback cooling of a nanodiamond hosting a single NV center in vacuum, a clear candidate to perform quantum physics experiments at the single spin level. Finally, we discuss and implement an optimal controller to cool the center of mass motion of an optically levitated nanoparticle. The feedback is realized by exerting a Coulomb force on a charged particle with a pair of electrodes, and thus requires no optics.La levitodinàmica és un camp de la física en ràpida expansió que estudia la levitació i manipulació de micro- i nano-objectes, empesa per la possibilitat de solucionar trencaclosques de física fonamental i de desenvolupar noves aplicacions tecnològiques. Gràcies al gran aïllament de les partícules en levitació, l’evolució dels sistemes levitodinàmics està molt desacoplada del seu entorn. Per consegüent, permeten fer experiments que no serien possibles en nanooscil·ladors mecànics sobre substrat. En particular, una qüestió central en física consisteix en entendre com es produeix la transició entre els mons clàssic i quàntic; els objectes en levitació permeten estudiar aquest règim intermedi de manera innovadora. En els últims anys, la majoria d’experiments de levitodinàmica s’han limitat a atrapar òpticament partícules de sílice en el buit, tot controlant la posició de la partícula amb feixos làser modulats. Tot i així, l’ús de trampes òptiques suposa un obstacle a l’hora d’exportar aquests experiments a règims més diversos perquè, a baixes pressions, pocs materials són capaços de suportar les altes temperatures resultants de l’absorció de llum làser. Això impedeix l’ús d’objectes amb graus de llibertat interns, que –acoplats a variables mecàniques– suposen un full de ruta clar per estudiar fenòmens quàntics a escala macroscòpica En aquesta tesi, adrecem aquestes qüestions tot considerant altres tipus de trampa i tècniques de feedback, i assolim un control excel·lent de la dinàmica de nanopartícules òpticament actives en levitació. Mitjançant càlcul estocàstic, simulacions i experiments, estudiem la dinàmica de les partícules en règims diversos, àdhuc considerant un esquema híbrid de trampa de Paul-òptica. A continuació, utilitzant una trampa de Paul, demostrem experimentalment l’atrapament, interrogació i feedback-cooling en el buit d’un nanodiamant que conté un únic NV− center, un clar candidat per a la realització d’experiments de física quàntica amb un únic spin. Finalment, estudiem i implementem un controlador òptim per a refredar el centre de massa d’una partícula òpticament levitada. El feedback es realitza exercint una força de Coulomb sobre una partícula carregada positivament mitjançant un parell d’elèctrodes, i per tant no requereix elements òptics
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Huthmann, Martin. "Free cooling of granular particles with rotational degrees of freedom." Doctoral thesis, [S.l. : s.n.], 1999. http://deposit.ddb.de/cgi-bin/dokserv?idn=963700979.
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Canbaloglu, Guvenc. "Structural Modification With Additional Degrees Of Freedom In Large Systems." Master's thesis, METU, 2009. http://etd.lib.metu.edu.tr/upload/2/12610664/index.pdf.
Повний текст джерелаАнотація:
In the design and development stages of mechanical structures, it is important to predict the dynamic characteristics of modified structures. Since time and cost are critical in design and development stage, structural modification methods predicting the dynamic responses of modified structures from those of the original structure and modification properties are very important, especially for large systems.
In this thesis structural modification methods are investigated and an effective structural modification method for modifications with additional degrees of freedom is adapted to structures with distributed modifications and the performance of the method is investigated. A software program is developed in order to apply the structural modification method with additional degrees of freedom. In the software, the dynamic response of the modified structure is predicted by using the modal analysis results of ANSYS for the original structure and dynamic stiffness matrix of the modifying structure. In order to validate the approach used and the program developed, the dynamic analysis results obtained for modified structures by ANSYS are compared with those obtained by using the software. In order to investigate the performance of the structural modification method in real applications, the method is applied to a scaled aircraft model, and the results are compared with experimental results.
In order to demonstrate the importance of using the structural modification method with additional degrees of freedom for distributed modification, lumped and distributed models are used for a distributed modification and results are compared.
It is concluded in this study that using structural modification methods with additional degrees of freedom for a distributed modification increases the accuracy of the results, and it is observed that the method adapted is efficient for local modifications.
38
Huang, Ming-Sheng. "Coupled elastic rotor/body vibrations with inplane degrees of freedom." Diss., Georgia Institute of Technology, 1987. http://hdl.handle.net/1853/12495.
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39
Chang, Woo Sok 1964. "A high precision three degrees of freedom friction drive stage." Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/80626.
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40
Spurr, James Christopher. "Statistically modelling tennis racket impacts with six degrees of freedom." Thesis, Sheffield Hallam University, 2017. http://shura.shu.ac.uk/18749/.
Повний текст джерелаАнотація:
The International Tennis Federation (ITF) is responsible for protecting the nature of tennis. The ITF uses computational models to predict how trends in equipment parameters could affect the games future. The current ball-racket impact model is limited to non-spinning, on-axis, normal ball impact simulations. The aim of this project was to develop a model of oblique, spinning, on- and off-axis ball-racket impacts. Large scale test data (n > 1000) was collected using an impact rig and calibrated high-speed cameras. Impacts for a range of realistic velocities, spin rates and impact locations were collected, measured using automated image processing algorithms to digitise ball centroids. An established spin measurement method was improved to correct for perspective errors associated with the proximity of the cameras to the test volume. The automated algorithms were validated with experimental data and manual methods. Multi-variate polynomial models to predict the lateral and vertical components of rebound velocities and rebound spin rate were trained and validated using a curve fitting toolbox and ‘n-fold and leave one out cross-validation’ method. Second order models best fit the training data, with the low predictive errors. Root-mean-squared errors were calculated using a test dataset, independent of the training data. These were 0.57 m·s-1 for the lateral rebound velocity model, 0.48 m·s-1 for the vertical rebound velocity model and 30.5 rad·s-1 for the rebound spin rate model. Variance was partially explained by experimentally established inherent variability of the ball and stringbed. Model output confidence was established by simulating small changes in model inputs. The simulated lateral and vertical components of rebound velocity, but not the simulated spin rate, were an order of magnitude greater than the measurement precision. The new models were combined with ball aerodynamics and ball-to-surface impact models to simulate tennis court trajectories for oblique, spinning, on- and off-axis ball-racket impacts. Increasing stringbed stiffness or the lateral offset of impact location were found to decrease rebound velocity and increase rebound angle – markedly so for a 60 mm lateral offset. Increasing lateral offset also increased the rebound spin rate.
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Biverot, Hans. "Multi-user retinal displays with two components. New degrees of freedom." Doctoral thesis, KTH, Physics, 2001. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3281.
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42
Skrøvseth, Stein Olav. "Entanglement and its applications in systems with many degrees of freedom." Doctoral thesis, Norwegian University of Science and Technology, Faculty of Natural Sciences and Technology, 2006. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-927.
Повний текст джерелаАнотація:
Entanglement are the non-local correlations permitted by quantum theory, believed to play a fundamental role in a quantum computer. We have investigated these correlations in a number of theoretical models for condensed matter systems. Such systems are likely candidates for quantum computing, and experimentally feasible for instance as superconducting qubits. At quantum critical points the ground state of these systems is very complicated, and the entanglement is usually larger than at non-critical points. This entanglement can be used to identify the critical points through what we denote the entanglement signature, even for very small systems. From another perspective, it seems that the entanglement is an essential tool to find an unknown ground state, since this gives rise to a simple decomposition of the state.
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Brouwer, Dannis Michel. "Design principles for six degrees-of-freedom MEMS-based precision manipulators." Enschede : University of Twente [Host], 2007. http://doc.utwente.nl/57871.
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Glaser, Rainer [Verfasser]. "Semiclassics for quantum systems with internal degrees of freedom / Rainer Glaser." Ulm : Universität Ulm. Fakultät für Naturwissenschaften, 2004. http://d-nb.info/1015471161/34.
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45
Grotz, Bernhard [Verfasser]. "Coupling Single NV Centers to External Degrees of Freedom / Bernhard Grotz." München : Verlag Dr. Hut, 2014. http://d-nb.info/1047037203/34.
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Yoo, Euisoo. "Investigating CMOS amplifier design using the Degrees of Design Freedom method." Thesis, McGill University, 2009. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=66813.
Повний текст джерелаАнотація:
A design methodology based on generating the performance space of amplifiers by sweeping independent control variables has been investigated. The method is used to optimize the performance of CMOS amplifiers with respect to gain, bandwidth, noise, distortion and power directly in SPICE without the aid of mathematical models or external software routines. The method works in all SPICE programs from Cadence to the student version of PSPICE. The technique is based on tuning the voltage of specific nodes of the amplifier using a self-biasing current source technique in conjunction with a replica amplifier circuit to span the entire performance space with a resolution of choice. The method has been tested with discrete implementation of the design. Both single-stage and multi-stage amplifiers are considered in this work. The method is generic, and it can be easily extended onto any amplifier topology for any performance measure.Une méthodologie de conception originale basée sur la production de l'espace desperformances des amplificateurs en balayant les variables de contrôle indépendantesest examinée. Cette méthodologie peut optimiser des amplificateurs de CMOS parrapport au gain, à la bande passante, au bruit, à la déformation et à la puissance.L'espace des performances est recherché directement dans les logiciels SPICE sansl'aide d'aucun modèle mathématique ou des logiciels externes. Cette méthode fonctionnedans tous les logiciels SPICE, allant de Cadence à la version d'étudiantde PSPICE. La technique est basée sur la variation de tension dans des noeudsspécifiques de l'amplificateur en utilisant une source de courante dépendente et, enparrallèle, un circuit d'amplificateur copie pour créer l'espace des performances completavec une résolution de choix. Cette méthodologie a été testé avec les composantesséparées. Des amplificateurs à étage unique et à étages multiples sont considérés dansce travail. Cette méthode est générique, et elle peut être facilement appliquée surn'importe quelle topologie d'amplificateur pour n'importe quelle mesure de performance.
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Taub, Daniel Matthew. "The BoPen : a tangible pointer tracked in six degrees of freedom." Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/61297.
Повний текст джерелаАнотація:
Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2009.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 77-86).
In this thesis, I designed and implemented an optical system for freehand interactions in six degrees of freedom. A single camera captures a pen's location and orientation, including roll, tilt, x, y, and z by reading information encoded in a pattern at the infinite focal plane. The pattern design, server-side processing, and application demo software is written in Microsoft C#.NET, while the client-side pattern recognition is integrated into a camera with an on-board DSP and programmed in C. We evaluate a number of prototypes and consider the pen's potential as an input device.
by Daniel Matthew Taub.
M.Eng.
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Mezei, Márk (Márk Koppany). "Counting degrees of freedom in quantum field theory using entanglement entropy." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/91389.
Повний текст джерелаАнотація:
Thesis: Ph. D., Massachusetts Institute of Technology, Department of Physics, 2014.141
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 199-208).
We devote this thesis to the exploration of how to define the number of degrees of freedom in quantum field theory. Intuitively, the number of degrees of freedom should decrease along the renormalization group (RG) flow, and should be independent of the RG scale at a conformal fixed point. We argue that a refinement of entanglement entropy is a promising candidate for such measure. Indeed, in two and three spacetime dimensions the number of degrees of freedom defined this way can be proven to monotonically decrease under RG flows. Firstly, we define renormalized entanglement entropy (REE) and show that it is finite in the continuum limit in a renormalizable field theory. We argue that it is most sensitive to degrees of freedom at a scale determined by the size of the entangling region, and interpolates between the ultraviolet and infrared RG fixed point vales. We discuss how it can be used to count the degrees of freedom at a given scale. Secondly, we test whether REE is monotonic along the RG flow. In two dimensions it was known to be monotonic before our study. In higher dimensions, we study REE in free theory examples and in the framework of holography. Holography is tailormade for the study of RG flows, and allows an efficient determination of entanglement entropy. We make use of its power and flexibility to conjecture that in three spacetime dimensions REE is monotonic, while in four dimensions it is neither monotonic nor positive. Subsequent work has proven the conjecture. Thirdly, we count the degrees of freedom in three-dimensional superconformal field theories that are the infrared limit of supersymrnetric gauge theories with matter. Supersymmetric localization reduces the computation of entanglement entropy to a matrix integral. We solve this matrix model in the large N number of colors limit using two different methods; in a saddle point approximation we obtain the next-to-leading order expression in 1/N, while mapping the matrix model to a non-interacting Fermi gas enables us to determine the result to all orders in 1/N. We match the leading piece with N3/ 2 scaling - a strong coupling phenomenon in the field theory - with the holographic duals of these theories. Establishing a measure for the number of degrees of freedom provides nonperturbative understanding of RG fixed points and flows. Our hope is that the constraints coming from RG monotonicity can be efficiently used to constrain the long-distance physics of certain systems of interest. The first applications are only starting to emerge.
by Márk Mezei.
Ph. D.
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Tournier, Glenn P. (Glenn Paul). "Six degrees of freedom estimation using monocular vision and moiré patterns." Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/37951.
Повний текст джерелаАнотація:
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2006.Includes bibliographical references (p. 105-107).
We present the vision-based estimation of the position and orientation of an object using a single camera relative to a novel target that incorporates the use of moire patterns. The objective is to acquire the six degree of freedom estimation that is essential for the operation of vehicles in close proximity to other craft and landing platforms. A target contains markers to determine relative orientation and locate two sets of orthogonal moire patterns at two different frequencies. A camera is mounted on a small vehicle with the target in the field of view. An algorithm processes the images extracting the attitude and position information of the camera relative to the target utilizing geometry and 4 single-point discrete Fourier transforms (DFTs) on the moire patterns. Manual and autonomous movement tests are conducted to determine the accuracy of the system relative to ground truth locations obtained through an external indoor positioning system. Position estimations with accompanying control techniques have been implemented including hovering, static platform landings, and dynamic platform landings to display the algorithm's ability to provide accurate information to precisely control the vehicle. The results confirm the moire target system's feasibility as a viable option for low-cost relative navigation for indoor and outdoor operations including landing on static and dynamic surfaces.
by Glenn P. Tournier.
S.M.
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Todd, Frankie. "Degrees of freedom : a study of collaborative learning in higher education." Thesis, University of York, 1989. http://etheses.whiterose.ac.uk/14032/.
Повний текст джерела