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Dissertations / Theses on the topic 'Joint geometry'
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Powers, Marilyn Joy. "Human patellofemoral kinematics and related joint surface geometry." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape7/PQDD_0015/MQ48068.pdf.
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Wathugala, Deepa Nelumkanthi. "Stochastic three dimensional joint geometry: Modeling and verification." Diss., The University of Arizona, 1991. http://hdl.handle.net/10150/185485.
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Eight 3D (three dimensional) rock joint geometry modeling schemes which investigate statistical homogeneity, and incorporate corrections for sampling biases and applications of stereology are presented. A procedure for verification of the developed models also is presented. In this study, shape of the joints was assumed as circular. The models provide the number of joint sets, and for each joint set, the intensity, orientation, spacing, location and diameter distributions. Miller's method (1983) with new interpretations (Kulatilake et al., 1990b) and equal area polar plots were used together to identify the largest statistically homogenous region around the ventilation drift, Stripa mine, data of which were used for both modeling and verification. Four joint sets were found in this region. A general vector approach to correct sampling bias on joint orientation is presented. Corrected data as well as raw data were subjected to chi-square goodness-of-fit tests to check the suitability of hemispherical normal and Bingham distributions in representing orientation of joint sets. Only raw data of joint set 4 followed Bingham distribution. Therefore, joint set orientations were best represented as empirical distributions. Two methods are presented for the modeling of joint spacing, linear intensity and location. In each method, spacing distributions of joint sets were best represented by exponential distributions. Then, joint intensity and location distributions are represented by Poisson and uniform distributions respectively. Correction of sampling bias on joint spacing also is presented. Joint size modeling was carried out using two methods: area sampling survey method and scanline sampling survey method. In these two methods, corrections of sampling biases associated with joint size modeling are presented. 3D joint sizes were inferred from 2D trace length measurements using geometrical probability and conditional probability concepts. In both methods diameter distributions are represented by gamma distributions. For verification, joints were generated in a volume according to the statistical models, using Monte-Carlo simulation. This volume was intersected by planes to obtain joint traces on exposures of size and shape similar to the ones used to obtain field data. Characteristics of these predicted joint traces were compared with the field data in a statistical sense. For the rock mass under this study, the modeling scheme 3 was found to be the most suitable scheme.
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Boroujeni, Farhad Iranpour. "The geometry and function of the patellofemoral joint." Thesis, University of London, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.522853.
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Leardini, Alberto. "Geometry and mechanics of the human ankle complex, and ankle prosthesis design." Thesis, University of Oxford, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.343530.
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Chikkamadal, Manjunatha Prathiksha. "Aitchison Geometry and Wavelet Based Joint Demosaicking and Denoising for Low Light Imaging." University of Dayton / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1627842487059544.
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Eriksson, Berth. "Residual stress in a T-butt joint weld : cylinder versus plane plate geometry." Licentiate thesis, Luleå tekniska universitet, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-25665.
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The welding process introduces residual stress originating from the heating, melting and cooling of the material. From the point of view of fatigue and stress corrosion cracking, the weld residual stress perpendicular to the weld axis is of particular interest. When qualifying weld parameters for welds in large cylinders having a ratio of radius to plate thickness larger than say approximately 100; reference to plane plates are often made for the sake of simplicity. However, the weld residual stress perpendicular to the weld axis is severely underestimated in the plane plate compared with the cylindrical structure. This observation is especially pronounced in connection with preheating. The source of the differences is probably due to the radial constraint of the cylinder, compared with that of a plane plate. A plane test specimen will underestimate the weld residual stress perpendicular to the weld axis in a cylinder, even if the radius of the cylinder is very large. However, a test specimen for an 8 m diameter cylinder with a plate thickness of 35 mm needs only to have a segment width of approximately 1.3 m to reflect the stress in the real structure. The weld residual stress perpendicular to the weld axis in the vicinity of the weld toe is governed by the depositing of the weld bead adjacent to the weld toe, neglecting the accumulated strain from the previous deposited weld beads in the multi-pass joint weld. Introducing tensile straining perpendicular to the weld axis during the entire welding procedure reduces the weld-induced residual stress after completed welding. The plastic zone of the weld area will be subjected to compressive strain after completed welding, which in turn will reduce the weld residual stress. This can be achieved by cooling the weld area, which in this case is not recommended since the material is sensitive to hydrogen cracking, or by pre-stretching or modifying the locations for preheating, all aimed to impose a tensile axial straining around the weld area during the entire welding process.<br>Godkänd; 2004; 20070131 (ysko)
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Rupassara, Rupassarage Upul Hemakumara. "Joint exit time and place distribution for Brownian motion on Riemannian manifolds." OpenSIUC, 2019. https://opensiuc.lib.siu.edu/dissertations/1720.
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This dissertation discusses the time and place that Brownian motion on a Riemannian manifold first exit a normal ball of small radius. A general procedure is given for computing asymptotic expansions of joint moments of the first exit time and place random variables as the radius of the geodesic ball decreases to zero. The asymptotic expansion of the joint Laplace transform of exit time and spherical harmonics of exit position is derived for a ball of small radius. A generalized Pizetti’s formula is used to expand the solution of the related partial differential equations. These expansions are represented in terms of curvature in the manifold. Asymptotic Independence Conditions (AIC) and Asymptotic Uncorrelated Conditions (AUC) are defined for the joint distributions of exit time and place. Computations using the methods developed in this work demonstrate that AIC and AUC produce the same curvature conditions up to a certain level of asymptotics. It is conjectured that AUC implies AIC. Further, a generalized method is given for computing the Laplace transform, and therefore the moments of the exit time. This work is related to and also extends the work of M. Liao and H. R. Hughes in stochastic geometric analysis.
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Lo, Chi Chuen. "Numerical prediction and experimental validation of flip chip solder joint geometry for MEMS applications /." View abstract or full-text, 2008. http://library.ust.hk/cgi/db/thesis.pl?MECH%202008%20LO.
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Bender, Matthew Jacob. "Modeling and Estimation of Bat Flight for Learning Robotic Joint Geometry from Potential Fields." Diss., Virginia Tech, 2018. http://hdl.handle.net/10919/85615.
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In recent years, the design, fabrication, and control of robotic systems inspired by biology has gained renewed attention due to the potential improvements in efficiency, maneuverability, and adaptability with which animals interact with their environments. Motion studies of biological systems such as humans, fish, insects, birds and bats are often used as a basis for robotic system design. Often, these studies are conducted by recording natural motions of the system of interest using a few high-resolution, high-speed cameras. Such equipment enables the use of standard methods for corresponding features and producing three-dimensional reconstructions of motion. These studies are then interpreted by a designer for kinematic, dynamic, and control systems design of a robotic system. This methodology generates impressive robotic systems which imitate their biological counter parts. However, the equipment used to study motion is expensive and designer interpretation of kinematics data requires substantial time and talent, can be difficult to identify correctly, and often yields kinematic inconsistencies between the robot and biology.
To remedy these issues, this dissertation leverages the use of low-cost, low-speed, low-resolution cameras for tracking bat flight and presents a methodology for automatically learning physical geometry which restricts robotic joints to a motion submanifold identified from motion capture data. To this end, we present a spatially recursive state estimator which incorporates inboard state correction for producing accurate state estimates of bat flight. Using these state estimates, we construct a Gaussian process dynamic model (GPDM) of bat flight which is the first nonlinear dimensionality reduction of flapping flight in bats. Additionally, we formulate a novel method for learning robotic joint geometry directly from the experimental observations. To do this, we leverage recent developments in learning theory which derive analytical-empirical potential energy fields for identifying an underlying motion submanifold. We use these energy fields to optimize a compliant structure around a single degree-of-freedom elbow joint and to design rigid structures around spherical joints for an entire bat wing. Validation experiments show that the learned joint geometry restricts the motion of the joints to those observed during experiment.<br>Ph. D.<br>In recent years, robots modeled after biological systems have become increasingly prevalent. Such robots are often designed based on motion capture experiments of the animal they aim to imitate. The motion studies are typically conducted using commercial motion capture systems such as ViconTM or OptiTrackTM or a few high-speed, high-resolution cameras such as those marketed by PhotronTM or PhantomTM. These systems allow for automated processing of video sequences into three-dimensional reconstructions of the biological motion using standard image processing and state estimation techniques. The motion data is then used to drive robotic system designs such as the SonyTM AiboTM dog and the Boston Dynamics Atlas humanoid robot. While the motion capture data forms a basis for these impressive robots, the progression from data to robotic system is neither algorithmic nor rigorous and requires substantial interpretation by a human. In contrast, this dissertation presents a novel experimental and computational framework which uses low-speed, low-resolution cameras for capturing the complex motion of bats in flight and introduces a methodology which uses the motion capture data to directly design geometry which restricts the motion of joints to the motions observed in experiment. The advantage of our method is that the designer only needs to specify a general joint geometry such as a ball or pin joint, and geometry which restricts the motion is automatically identified. To do this, we learn an energy field over the set of kinematic configurations observed during experiment. This energy field “pushes” system trajectories towards those experimentally observed trajectories. We then learn compliant or rigid geometry which approximates this energy field to physically restrict the range of motion of the joint. We validate our method by fabricating joint geometry designed using both these approaches and present experiments which confirm that the reachable set of the joint is approximately the same as the set of configurations observed during experiments.
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Wilson, David Robert. "Three-dimensional kinematics of the knee." Thesis, University of Oxford, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.320163.
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Soysal, Medeni. "Joint Utilization Of Local Appearance Descriptors And Semi-local Geometry For Multi-view Object Recognition." Phd thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614313/index.pdf.
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Novel methods of object recognition that form a bridge between today&rsquo<br>s local feature frameworks and previous decade&rsquo<br>s strong but deserted geometric invariance field are presented in this dissertation. The rationale behind this effort is to complement the lowered discriminative capacity of local features, by the invariant geometric descriptions. Similar to our predecessors,
we first start with constrained cases and then extend the applicability of our methods to more general scenarios. Local features approach, on which our methods are established, is
reviewed in three parts<br>namely, detectors, descriptors and the methods of object recognition that employ them. Next, a novel planar object recognition framework that lifts the requirement
for exact appearance-based local feature matching is presented. This method enables matching of groups of features by utilizing both appearance information and group geometric
descriptions. An under investigated area, scene logo recognition, is selected for real life application of this method. Finally, we present a novel method for three-dimensional (3D) object recognition, which utilizes well-known local features in a more efficient way without any reliance on partial or global planarity. Geometrically consistent local features, which form
the crucial basis for object recognition, are identified using affine 3D geometric invariants. The utilization of 3D geometric invariants replaces the classical 2D affine transform estimation
/verification step, and provides the ability to directly verify 3D geometric consistency. The accuracy and robustness of the proposed method in highly cluttered scenes with no prior
segmentation or post 3D reconstruction requirements, are presented during the experiments.
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Andreou, Antonios. "The influence of facet joint geometry on lumbar segmental kinematics : an ex-vivo & in-vivo study." Thesis, McGill University, 1997. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=20240.
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It has long been postulated that the facet joint geometry (FJG) has an important influence on lumbar segmental motion. Although their sagittal orientation has been described in detail, there are very few studies describing the three-dimensional (3D) FJG. None correlates the latter to segmental kinematics. In view, we developed a method to quantify 3D FJG and compared the results to segmental kinematics.<br>In the ex-vivo set-up, facets of individual cadaveric vertebrae taken from a previous biomechanical. study were digitized using a 3D morphometer and the geometry of the facet joints in respect to the vertebra's local coordinate system was quantified. In the in-vivo set-up, re-recruited subjects from a previous kinematic study had a MRI of their lumbar spine. The images were digitized and the facet joint's 3D geometry was evaluated. The two methods used for FJG measurements were validated. Kinematic data derived from both previous studies was correlated with their respective FJG.<br>We did not find a significant influence of the FJG or tropism on lumbar segmental kinematics. Different coupling patterns were measured in the ex-vivo and in in-vivo experiments. This is likely due to the absence of muscle activity in the cadaveric specimen. Future in-vivo studies should be done with simultaneous muscle activity recording to better understand the coupling patterns. Studying FJG in defined spinal pathologies may render valuable information on the etiology of spinal diseases.
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Andreou, Antonios. "The influence of facet joint geometry on lumbar segmental kinematics, an ex-vivo and in-vivo study." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0005/MQ44116.pdf.
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Ucpirti, Hasan. "Joint geometry parameter effects on deformability and strength of jointed rock masses at the two dimensional level." Diss., The University of Arizona, 1992. http://hdl.handle.net/10150/185975.
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In this study, the pre-failure behavior of a jointed rock block is modeled by an incrementally linear elastic anisotropic constitutive model (using an orthotropic model in 2D). In order to estimate the parameters in the constitutive model, a new technique was used in this dissertation. A 2D joint geometry generation code was used to generate finite size actual joint networks in 2D rock blocks. A 2D distinct element code (UDEC) was chosen as the stress analysis tool in this study. Fictitious joints were introduced into the rock blocks which contain finite size actual joints to discretize the problem domain into polygons. A number of stress analyses of rock blocks which contain only persistent joints were performed to estimate representative values for mechanical properties of fictitious joints to simulate the intact rock behavior. Finally, the rock blocks having different deterministic actual joint configurations with fictitious joints were subjected to 2D stress analysis under various stress paths using UDEC. Results of these stress analyses were used to estimate the deformational and strength properties of these rock blocks. Influence of joint geometry parameters on the mechanical properties of jointed rock blocks were found to be very significant. Plots are given to show how mechanical properties of rock blocks vary with joint intensity and joint size/block size for different joint orientations. These plots can also be used to estimate REV (Representative Elementary Volume) size and REV properties for rock masses. It is important to note that these REV property values depend on the chosen constitutive models for intact rock and joints. The concept of fracture tensor is reviewed at the 2D level. Relationships between the mechanical properties of jointed rock blocks and the fracture tensor parameters (its first invariant and components) are established. These relationships can be used to estimate the parameters of the chosen constitutive model for the rock block. This constitutive model has captured both scale dependent and anisotropic behaviors of rock masses. The possibility of obtaining the equivalent continuum properties (REV properties) of jointed rock blocks is explored by using the aforementioned relationships. (Abstract shortened by UMI.)
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Lanaro, Flavio. "Geometry, Mechanics and Transmissivity of Rock Fractures." Doctoral thesis, Stockholm : Tekniska högsk, 2001. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3168.
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Brahmachari, Aveek Shankar. "BLOGS: Balanced Local and Global Search for Non-Degenerate Two View Epipolar Geometry." [Tampa, Fla] : University of South Florida, 2009. http://purl.fcla.edu/usf/dc/et/SFE0003084.
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Fisher, Ian Alexander. "A mathematical investigation of the influence of skeletal geometry on the mechanics of a prosthetic human hip joint." Thesis, Imperial College London, 2000. http://hdl.handle.net/10044/1/7881.
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Jha, Rajan. "Elevation based classification of streams and establishment of regime equations for predicting bankfull channel geometry." Thesis, Virginia Tech, 2013. http://hdl.handle.net/10919/51801.
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Since past more than hundred years, fluvial geomorphologists all across the globe have been trying to understand the basic phenomena and processes that control the behavioral patterns of streams. A large number of stream classification systems has been proposed till date, but none of them have been accepted universally. Lately, a large amount of efforts have been made to develop bankfull relations for estimating channel geometry that can be employed for stream restoration practices. Focusing on these two objectives, in this study a new stream classification system based on elevation above mean sea level has been developed and later using elevation as one of the independent and nondimensionalising parameters, universal and regional regime equations in dimensionless forms have been developed for predicting channel geometry at bankfull conditions.
To accomplish the first objective, 873 field measurement values describing the hydraulic geometry and morphology of streams mainly from Canada, UK and USA were compiled and statistically analyzed. Based on similar mode values of three dimensionless channel variables (aspect ratio, sinuosity and channel slope), several fine elevations ranges were merged to produce the final five elevation ranges. These final five zones formed the basis of the new elevation based classification system and were identified with their unique modal values of dimensionless variables. Performing joint probability distributions on each of these zones, trends in the behavior of channel variables while moving from lowland to upland were observed. For the completion of second objective, 405 data points out of initial 873 points were selected and employed for the development of bankfull relations by using bankfull discharge and watershed variables as the input variables. Regression equations developed for width and depth established bankfull discharge as the only required input variable whereas all other watershed variables were proved out to be relatively insignificant. Channel slope equation did not show any dependence on bankfull discharge and was observed to be influenced only by drainage area and valley slope factors. Later when bankfull discharge was replaced by annual average rainfall as the new input variable, watershed parameters (drainage area, forest cover, urban cover etc.) became significant in bankfull width and depth regression equations. This suggested that bankfull discharge in itself encompasses the effects of all the watershed variables and associated processes and thus is sufficient for estimating channel dimensions. Indeed, bankfull discharge based regression equation demonstrated its strong dependence on watershed and rainfall variables.<br>Master of Science
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Habouh, Mohamed I. "Key Way Joint Strength of Precast Box-Beam Bridges." University of Akron / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=akron1449337726.
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Huang, Zhiheng. "Materials issues in the transition to lead-free solder alloys and joint miniaturization." Thesis, Loughborough University, 2005. https://dspace.lboro.ac.uk/2134/25232.
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Within the context of the imminent implementation of the Pb-free soldering in Europe in 2006, this thesis addresses the gap in understanding that has emerged in the fundamental materials issues between well-understood and mature lead-containing solders and a plethora of new, Pb-free solders for which there are neither long term reliability data nor understanding of the materials behaviour and how these might be influenced by manufacture and in-service conditions. In addition, this thesis also addresses the question as to whether the solder joint size and geometry could become a reliability issue and therefore affect the implementation of the Pb-free solders in ultrafine micro joints. Thermodynamic calculations using MTDATA (developed by the National Physical Laboratory, NPL, UK) together with a thermodynamic database for solders under either equilibrium or Scheil conditions, have shown their usefulness in Pb-free solder design and processing, generating a wealth of information in respect of the temperature dependence of phase formation and composition. The predictions from MTDATA on a number of selected systems is generally in good agreement with the results from experimental work, and has assisted in the understanding of the microstructure and mechanical properties of the Pb-free solders and the implications of their interactions with a tin-lead solder. However, further critical assessment and the addition of new elements into the solder database, such as Ni and P, are required to make MTDA TA a more effective computational tool to assist the optimization of processing parameters and cost-effective production in using Pb-free solders. Molten solder can interact with the under bump metallizations (UBM) and/or board level metallizations on either side of the solder bump to form intermetallic compounds (IMCs) during solder reflow. In the modelling of the kinetics of the dissolution process of UBM into the liquid solder, the commonly used NernstBrunner (N-B) equation is found to have poor validity for these calculations for micro joints at 100 μm in diameter or less. Three bumping techniques, i.e. solder dipping (SD), solder paste stencil printing followed by reflow (SPR) and electroplating of solders and subsequent reflow (EPR), are used to investigate the interfacial interactions of molten Sn/Sn-rich solders, i.e. pure Sn, Sn-3.5Ag, and Sn-3.8AgO.7Cu, on electroless nickel immersion gold (ENIG) and copper pads at 240°C. The resultant bulk and interfacial microstructures from a variety of pad sizes, ranging from 1 mm down to 25 μm, suggest that in general the small bumps contain smaller β-Sn dendrites and Ag₃Sn IMC particles, nevertheless the interfacial IMC is thicker in the smalI bumps than in the large bumps. In addition, one and two-dimensional combined thermodynamic and kinetic models have been developed to assist the understanding of the kinetics of interdiffusion and the formation of interfacial intermetallic compounds during reflow. Both the experimental results and theoretical predictions suggest that the solder bump size and geometry can influence the as-soldered microstructure, and therefore this factor should be taken into consideration for the design of future reliable ultrafine Ph-free solder joints.
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Ji, Xiang. "The association of variations in hip and pelvic geometry with pregnancy-related sacroiliac joint pain based on a longitudinal analysis." Kyoto University, 2019. http://hdl.handle.net/2433/242658.
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Hartsfield, J. Carl (Jasper Carl). "Single Transponder Range Only Navigation Geometry (STRONG) applied to REMUS autonomous under water vehicles." Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/39175.
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Thesis (S.M.)--Joint Program in Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Dept. of Mechanical Engineering; and the Woods Hole Oceanographic Institution), 2005.<br>Includes bibliographical references (leaves 124-125).<br>A detailed study was conducted to prove the concept of an iterative approach to single transponder navigation for REMUS Autonomous Underwater Vehicles (AUVs). Although the concept of navigation with one acoustic beacon is not new, the objective was to develop a computer algorithm that could eventually be integrated into the REMUS architecture. This approach uses a least squares fit routine coupled with restrictive geometry and simulated annealing vice Kalman filtering and state vectors. In addition, to provide maximum flexibility, the single transponder was located on a GPS equipped surface ship that was free to move instead of the more common single bottom mounted beacon. Using only a series of spread spectrum ranges logged with time stamp, REMUS standard vehicle data, and reasonable initial conditions, the position at a later time was derived with a figure of merit fit score. Initial investigation was conducted using a noise model developed to simulate the errors suspected with the REMUS sensor suite. Results of this effort were applied to a small at sea test in 3,300 meters with the REMUS 6000 deep water AUV. A more detailed test was executed in Buzzard's Bay, Massachusetts, in 20 meters of water with a REMUS 100 AUV focusing on navigation in a typical search box.<br>(cont.) While deep water data was too sparse to reveal conclusive results, the Buzzard's Bay work strongly supports the premise that an iterative algorithm can reliably integrate REMUS logged data and an accurate time sequence of ranges to provide position fixes through simple least squares fitting. Ten navigational legs up to 1500 meters in length showed that over 90% of the radial position error can be removed from an AUV's position estimate using the STRONG algorithm vice dead reckon navigation with a magnetic compass and Doppler Velocity Log alone (DVL).<br>by J. Carl Hartsfield, Jr.<br>S.M.
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Fischell, Erin Marie. "Characterization of underwater target geometry from autonomous underwater vehicle sampling of bistatic acoustic scattered fields." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/100161.
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Thesis: Ph. D., Joint Program in Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Department of Mechanical Engineering; and the Woods Hole Oceanographic Institution), 2015.<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references (pages 153-156).<br>One of the long term goals of Autonomous Underwater Vehicle (AUV) minehunting is to have multiple inexpensive AUVs in a harbor autonomously classify hazards. Existing acoustic methods for target classification using AUV-based sensing, such as sidescan and synthetic aperture sonar, require an expensive payload on each outfitted vehicle and expert image interpretation. This thesis proposes a vehicle payload and machine learning classification methodology using bistatic angle dependence of target scattering amplitudes between a fixed acoustic source and target for lower cost-per-vehicle sensing and onboard, fully autonomous classification. The contributions of this thesis include the collection of novel high-quality bistatic data sets around spherical and cylindrical targets in situ during the BayEx'14 and Massachusetts Bay 2014 scattering experiments and the development of a machine learning methodology for classifying target shape and estimating orientation using bistatic amplitude data collected by an AUV. To achieve the high quality, densely sampled 3D bistatic scattering data required by this research, vehicle broadside sampling behaviors and an acoustic payload with precision timed data acquisition were developed. Classification was successfully demonstrated for spherical versus cylindrical targets using bistatic scattered field data collected by the AUV Unicorn as a part of the BayEx'14 scattering experiment and compared to simulated scattering models. The same machine learning methodology was applied to the estimation of orientation of aspect-dependent targets, and was demonstrated by training a model on data from simulation then successfully estimating the orientations of a steel pipe in the Massachusetts Bay 2014 experiment. The final models produced from real and simulated data sets were used for classification and parameter estimation of simulated targets in real time in the LAMSS MOOS-IvP simulation environment.<br>by Erin Marie Fischell.<br>Ph. D.
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Arvaneh, Tia. "Morphometric Analysis of the Talus on the Cohort of Healthy and Arthritic Patient Population:." Scholar Commons, 2017. http://scholarcommons.usf.edu/etd/6797.
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Prevalence of osteoarthritis (OA) is less common in the ankle compared to other joints; however, deformation brought on by degeneration causes pain, loss of function, and overall decreased quality of life. Current surgical interventions for end-stage ankle OA are not as reliable as surgical treatments for other joints. Ankle arthroplasty currently has high failure rates, and there are lack of substantial data from long-term outcome studies. By understanding the morphometric changes that occur during the different stages of OA, we are able to identify early signs of the disease with the intention to apply treatment earlier in order to preclude the need for end-stage surgical intervention. The goals of this study are to assess morphometric parameters of the talus as it relates to the progression of OA and to evaluate the effect of gender and anatomical side. A retrospective study was performed where data from sixty-eight CT scans were obtained from two study groups, one with OA and one without. The subjects were segmented, standardized, and normalized in order to study several 3D parameters of the talus, including height, radius of curvature, and volume. Results showed that talar morphometry is influenced by gender and that geometric changes are a function of OA progression. The lateral radii of subjects with OA was significantly larger than those of normal ankles (p<0.0001), and there is evidence of inherent changes between KL grades (p=0.0003). Identifying morphometric changes of the talus at each stage of OA can inherently contribute to better understanding the degenerative process. Assessing specific characteristics at earlier stages of the diseases may help clinicians to diagnose more accurately and to better provide treatment.
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Standish, Jared Jeffrey. "The influence of ridge geometry at the ultraslow-spreading Southwest Indian Ridge (9°-25°E) : basalt composition sensitivity to variations in source and process /." Thesis, Cambridge, Mass. : Woods Hole, Mass. : Massachusetts Institute of Technology ; Woods Hole Oceanographic Institution, 2006. http://hdl.handle.net/1912/1508.
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Originally issued as the author's thesis (Ph. D.)--Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 2005.<br>"February 2006". "Doctoral dissertation." "Department of origin: Geology and Geophysics." "Joint Program in Oceanography/Applied Ocean Science and Engineering"--Cover. Includes bibliographical references.
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Guislain, Maximilien. "Traitement joint de nuage de points et d'images pour l'analyse et la visualisation des formes 3D." Thesis, Lyon, 2017. http://www.theses.fr/2017LYSE1219/document.
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Au cours de la dernière décennie, les technologies permettant la numérisation d'espaces urbains ont connu un développement rapide. Des campagnes d'acquisition de données couvrant des villes entières ont été menées en utilisant des scanners LiDAR (Light Detection And Ranging) installés sur des véhicules mobiles. Les résultats de ces campagnes d'acquisition laser, représentants les bâtiments numérisés, sont des nuages de millions de points pouvant également contenir un ensemble de photographies. On s'intéresse ici à l'amélioration du nuage de points à l'aide des données présentes dans ces photographies. Cette thèse apporte plusieurs contributions notables à cette amélioration. La position et l'orientation des images acquises sont généralement connues à l'aide de dispositifs embarqués avec le scanner LiDAR, même si ces informations de positionnement sont parfois imprécises. Pour obtenir un recalage précis d'une image sur un nuage de points, nous proposons un algorithme en deux étapes, faisant appel à l'information mutuelle normalisée et aux histogrammes de gradients orientés. Cette méthode permet d'obtenir une pose précise même lorsque les estimations initiales sont très éloignées de la position et de l'orientation réelles. Une fois ces images recalées, il est possible de les utiliser pour inférer la couleur de chaque point du nuage en prenant en compte la variabilité des points de vue. Pour cela, nous nous appuyons sur la minimisation d'une énergie prenant en compte les différentes couleurs associables à un point et les couleurs présentes dans le voisinage spatial du point. Bien entendu, les différences d'illumination lors de l'acquisition des données peuvent altérer la couleur à attribuer à un point. Notamment, cette couleur peut dépendre de la présence d'ombres portées amenées à changer avec la position du soleil. Il est donc nécessaire de détecter et de corriger ces dernières. Nous proposons une nouvelle méthode qui s'appuie sur l'analyse conjointe des variations de la réflectance mesurée par le LiDAR et de la colorimétrie des points du nuage. En détectant suffisamment d'interfaces ombre/lumière nous pouvons caractériser la luminosité de la scène et la corriger pour obtenir des scènes sans ombre portée. Le dernier problème abordé par cette thèse est celui de la densification du nuage de points. En effet la densité locale du nuage de points est variable et parfois insuffisante dans certaines zones. Nous proposons une approche applicable directement par la mise en oeuvre d'un filtre bilatéral joint permettant de densifier le nuage de points en utilisant les données des images<br>Recent years saw a rapid development of city digitization technologies. Acquisition campaigns covering entire cities are now performed using LiDAR (Light Detection And Ranging) scanners embedded aboard mobile vehicles. These acquisition campaigns yield point clouds, composed of millions of points, representing the buildings and the streets, and may also contain a set of images of the scene. The subject developed here is the improvement of the point cloud using the information contained in the camera images. This thesis introduces several contributions to this joint improvement. The position and orientation of acquired images are usually estimated using devices embedded with the LiDAR scanner, even if this information is inaccurate. To obtain the precise registration of an image on a point cloud, we propose a two-step algorithm which uses both Mutual Information and Histograms of Oriented Gradients. The proposed method yields an accurate camera pose, even when the initial estimations are far from the real position and orientation. Once the images have been correctly registered, it is possible to use them to color each point of the cloud while using the variability of the point of view. This is done by minimizing an energy considering the different colors associated with a point and the potential colors of its neighbors. Illumination changes can also change the color assigned to a point. Notably, this color can be affected by cast shadows. These cast shadows are changing with the sun position, it is therefore necessary to detect and correct them. We propose a new method that analyzes the joint variation of the reflectance value obtained by the LiDAR and the color of the points. By detecting enough interfaces between shadow and light, we can characterize the luminance of the scene and to remove the cast shadows. The last point developed in this thesis is the densification of a point cloud. Indeed, the local density of a point cloud varies and is sometimes insufficient in certain areas. We propose a directly applicable approach to increase the density of a point cloud using multiple images
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Stüpp, Ângela. "Avaliação do desempenho de emendas por entalhes múltiplos para estruturas em madeira laminada colada." Universidade do Estado de Santa Catarina, 2016. http://tede.udesc.br/handle/handle/2330.
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Previous issue date: 2016-07-29<br>UNIEDU<br>FUMDES<br>The geometry of finger joint is one of the most important variables when determining the connection strength among timber with structural use purpose. This research aimed to evaluate three finger joint geometries and its correlation with three species of timber from reforestation and three adhesives used for structural purposes. The species were: Eucalyptus grandis, Pinus taeda and Schizolobium parahyba var. amazonicum (known as paricá), and the adhesives: resorcinol formaldehyde, melamine urea formaldehyde and reactive polyurethane. Finger profiles were produced by means of a spindle moulder, glued and pressed in manufacture plant and laboratory. Then, the specimens were flattened obtaining the dimensions as recommended by NBR 7190/1997. The finger joint geometry was measured with a digital caliper, the specimens were tested and the failure modes determined. Statistical analysis was done by evaluating the geometric means by Tukey test with 95% probability. Results showed that E. grandis produced with resorcinol adhesive from geometry B, had the highest tensile strength parallel to the fibers (67,55 MPa). Also, the higher tensile strength values were from the specimens with higher basic density. As for failure modes, 64% of the specimens failed in modes number 3 (14%) and 4 (50%). It was found that all evaluated factors interfered in the results of resistance and, regarding the determination of the best geometry, specie and adhesive, these can not be analyzed separately<br>A geometria da emenda por entalhes múltiplos é uma das variáveis mais importantes quando se determina a resistência da ligação entre madeiras com finalidade de uso estrutural. O objetivo da pesquisa foi avaliar três geometrias de emendas por entalhes múltiplos e sua correlação com três espécies de madeira de florestas plantadas e três adesivos utilizados para fins estruturais. As espécies foram o Eucalyptus grandis, o Pinus taeda e o Schizolobium parahyba var amazonicum (paricá), e os adesivos: resorcina formaldeído, melamina ureia formaldeído e poliuretano reativo. Os corpos de prova foram fresados, colados e prensados em parque fabril e em laboratório. Posteriormente, eles foram aplainados obtendo-se as dimensões conforme orientação da NBR 7190/1997. Foram medidas as geometrias com paquímetro digital, realizados pré-testes e determinados os modos de ruptura. A análise estatística foi feita avaliando-se as médias de geometria pelo teste de Tukey a 95% de probabilidade. Dos resultados obtidos, destaca-se a espécie E. grandis produzida com o adesivo resorcina da geometria B, que teve a maior resistência à tração paralela às fibras (67,55 MPa). Também, os maiores valores de tensão foram provenientes dos corpos de prova com maior densidade básica. Quanto aos modos de ruptura, 64% dos corpos de prova romperam pelos tipos 3 (14%) e 4 (50%). Verificou-se que todos os fatores avaliados interferiram nos resultados de resistência e, no que se refere à determinação damelhor geometria, melhor espécie e melhor adesivo, não podem ser analisados separadamente
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Athias, Francine. "La géométrie dynamique comme moyen de changement curriculaire." Thesis, Aix-Marseille, 2014. http://www.theses.fr/2014AIXM3057.
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La géométrie à l'école primaire consiste en une familiarisation avec des formes géométriques et leurs propriétés, à travers l'utilisation d'instruments de géométrie. Les objets géométriques reposent sur les représentations graphiques, les relations géométriques sont souvent implicites. L'introduction d'un logiciel de géométrie dynamique (TracenPoche) est vu comme un moyen de les expliciter, conduisant ainsi à voir le dessin comme une figure. Nous avons proposé à des professeurs une série de cinq situations, que nous avons conçues à partir des modes d'intégration de Assude (2007). Nous en proposons une analyse a priori en trois temps (Assude et Mercier, 2007), une analyse a priori du point de vue des savoirs mathématiques, une analyse a priori ascendante du point de vue des actions des élèves modélisée en terme de praxéologie (Chevallard, 1998) et une analyse a priori du point de vue de l'enseignant. Les situations mises en oeuvre dans les classes sont décrites et analysées à l'aide d'éléments de la théorie de l'action conjointe en didactique (TACD, Sensevy, 2011). Nous décrivons l'action conjointe du professeur et des élèves comme un jeu du professeur sur l'élève, permettant ainsi de rendre compte de la dynamique du travail didactique et de l'évolution du « voir un dessin comme une figure ». Les résultats de la thèse, dans le cadre de cette ingénierie exploratoire (Perrin-Glorian, 2009), montrent comment les objets géométriques peuvent être travaillés conjointement dans l'environnement papier-crayon et dans l'environnement tracenpoche, mettant en évidence des caractéristiques de l'action conjointe du professeur et des élèves dans l'explicitation des relations géométriques<br>Geometry in primary school is a familiarization with geometric shapes and their properties through the use of geometrical instruments. Geometric objects are based on diagrams and the geometric relationships are often implicit. The introduction of a dynamic geometry software (here TracenPoche) is thus a way to explain how to see « the diagram » as « a figure ». Five situations are given to three teachers. We have built them with « integration modes » from Assude (2007). We proposed an a priori analysis in three stages (Assude and Mercier, 2007), the first a priori analysis - the viewpoint of mathematical knowledge - , the second a priori analysis - students action modelized by the praxeology (Chevallard, 1998) - and the third a priori analysis - the teacher's point of view - . The Situations established in classrooms are described and analyzed using elements of the joint action theory (Sensevy, 2011). We describe the joint action of the teacher and students as a game of the teacher on the student, thereby enabling an analysis of the dynamic of the teaching work and of the evolution of the "seeing a diagram as a figure." The results of this thesis, as part of the exploratory engineering (Perrin-Glorian, 2009), show how geometrical objects can be worked jointly in a paper-and-pencil environment and in a Tracenpoche environment, highlighting the characteristics of the joint action of the teacher and students in the explanation of geometric relationships. The teachers demonstrate initiatives that prove particularly interesting with regard to mathematical issues, and which could be the basis for further research in cooperative engineering (Sensevy & al., 2013)
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Bouchard, Florent. "Géométrie et optimisation riemannienne pour la diagonalisation conjointe : application à la séparation de sources d'électroencéphalogrammes." Thesis, Université Grenoble Alpes (ComUE), 2018. http://www.theses.fr/2018GREAS030/document.
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La diagonalisation conjointe approximée d’un ensemble de matrices permet de résoudre le problème de séparation aveugle de sources et trouve de nombreuses applications, notamment pour l’électroencéphalographie, une technique de mesure de l’activité cérébrale.La diagonalisation conjointe se formule comme un problème d’optimisation avec trois composantes : le choix du critère à minimiser, la contrainte de non-dégénérescence de la solution et l’algorithme de résolution.Les approches existantes considèrent principalement deux critères, les moindres carrés et la log-vraissemblance.Elles sont spécifiques à une contrainte et se restreignent à un seul type d’algorithme de résolution.Dans ce travail de thèse, nous proposons de formuler le problème de diagonalisation conjointe selon un modèle géométrique, qui généralise les travaux précédents et permet de définir des critères inédits, notamment liés à la théorie de l’information.Nous proposons également d’exploiter l’optimisation riemannienne et nousdéfinissons un ensemble d’outils qui permet de faire varier les trois composantes indépendamment, créant ainsi de nouvelles méthodes et révélant l’influence des choix de modélisation.Des expériences numériques sur des données simulées et sur des enregistrements électroencéphalographiques montrent que notre approche par optimisation riemannienne donne des résultats compétitifs par rapport aux méthodes existantes.Elles indiquent aussi que les deux critères traditionnels ne sont pas les meilleurs dans toutes les situations<br>The approximate joint diagonalisation of a set of matrices allows the solution of the blind source separation problem and finds several applications, for instance in electroencephalography, a technique for measuring brain activity.The approximate joint diagonalisation is formulated as an optimization problem with three components: the choice of the criterion to be minimized, the non-degeneracy constraint on the solution and the solving algorithm.Existing approaches mainly consider two criteria, the least-squares and the log-likelihood.They are specific to a constraint and are limited to only one type of solving algorithms.In this thesis, we propose to formulate the approximate joint diagonalisation problem in a geometrical fashion, which generalizes previous works and allows the definition of new criteria, particularly those linked to information theory.We also propose to exploit Riemannian optimisation and we define tools that allow to have the three components varying independently, creating in this way new methods and revealing the influence of the choice of the model.Numerical experiments on simulated data as well as on electroencephalographic recordings show that our approach by means of Riemannian optimisation gives results that are competitive as compared to existing methods.They also indicate that the two traditional criteria do not perform best in all situations
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Nerman, Peter. "Influence of defects and geometry in welded joints." Licentiate thesis, Stockholm, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-306.
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Huťka, Pavel. "Deformačně napěťová analýza TEP kyčelního kloubu – typ Santori." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2008. http://www.nusl.cz/ntk/nusl-378901.
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Submitted Diploma thesis deals with stress-strain analysis of deformation proximal end of femur with applied total hip joint endoprosthesis (replacement) – shortcut type. To identify deformation and tensity (stress) was used computational simulation by method of final elements. Have been created two computational models TEP- type Santori and type DePuy Proxima. Geometry model Santori was created on low level model geometry through the use of X-ray photograph. Principle of geometry model type DePuy Proxima was real Femoral stem endoprosthesis which was scanned on scanner ATOS. Geometry of both these replacements were set up in program Rhinoceros 4.0 and then execute in program CatiaV5R17. Data for geometry model of femur were gained from CT chains. Material model of femur have been crated in two variants. The first one looks at structure bone tissues and the second one were created by Gruen´s zones. Femoral Stem was weighted by static equivalent resultant force acting in hip joint. Computational model of system and self solution, including depiction results, was done by ANSYS Workbench 11.0 for four model variants.
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Padmanabhan, Babu. "Design of a robotic manipulator using variable geometry trusses as joints." Thesis, Virginia Polytechnic Institute and State University, 1989. http://hdl.handle.net/10919/53240.
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Parallel robotic manipulators are generally believed to be stiffer under load and more precise than conventional serial manipulators. This is because of their closed loop construction which allows forces to be shared through multiple paths to the ground. Unfortunately, most proposed parallel manipulator designs have severe workspace restrictions. The introduction of Variable Geometry Trusses (VGT’s) represents an opportunity to overcome this limitation.
The lack of stiffness in many serial manipulators is primarily due to compliance at the joints. The disadvantage of the series connected device include limitations in lilting capacity and vibration problems. Difficulties of this sort result from the cantilever structure of the device. These factors often limit the degrees of freedom that can be provided in the serial configuration. By replacing the revolute joints with the ‘VGT joints’, it may be possible to add considerable rigidity at the joints and hence design a highly dextrous manipulator.
The objective of this thesis is to study the feasibility of a design of manipulators using Variable Geometry Trusses. A modeling scheme capable of solving the inverse problem in closed form and finding the range of all possible solutions for a planar VGT has been presented. Another aspect that has been dealt with is in utilizing the extra degree of freedom that becomes available in the proposed manipulator. Enhancing the performance of the manipulator by optimizing relevant parameters has been carried out for a demonstrative case involving a planar truss.<br>Master of Science
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Gribble, Paul L. "Musculo-skeletal geometry and the control of single degree of freedom elbow movements." Thesis, McGill University, 1995. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=22735.
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Empirical and modelling studies are reported which explore ways in which the central nervous system might consider musculo-skeletal geometry when generating commands for single degree of freedom elbow flexion and extension movements. In a series of experiments it is shown that subjects do not perform rapid, goal-directed flexion and extension movements equally accurately in different parts of the elbow's workspace. In these experiments, movements of 10, 20 and 30 degrees in amplitude were tested using up to five different initial elbow angles. When performing flexions, subjects tended to overshoot targets when starting from extended positions, to undershoot targets when starting from more flexed positions, and to perform relatively accurate movements when starting from the centre of the workspace. Final position accuracy was more variable for extensions. When reliable differences existed for extensions, subjects tended to produce a pattern of results opposite to that of flexions: subjects overshot targets when starting from flexed positions and undershot targets when starting from more extended positions. A model of elbow movement based on the $ lambda$ version of the equilibrium-point hypothesis was used to assess the extent to which the pattern of errors obtained in the empirical studies could be reproduced by a control scheme that does not adjust commands in response to changing musculo-skeletal geometry, but rather uses one single invariant command throughout the workspace. The motivation for testing the invariant command notion was to explore the possibility that motion planning might be achieved without an explicit representation of musculo-skeletal geometry. Predicted patterns of final position errors across the workspace matched empirically obtained error patterns for flexions, but the model performed less well when predicting the pattern of errors observed for extension movements.
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Tu, Wei. "Comeld™ joints : optimisation of geometric parameters of the protrusions." Thesis, Queen Mary, University of London, 2011. http://qmro.qmul.ac.uk/xmlui/handle/123456789/2449.
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Current and future structural applications for composite laminates frequently involve design solutions combining composite laminates and metal; the materials must be joined. Two conventional means of joining are available: mechanical joining and adhesive bonding. Both methods have critical disadvantages. A novel surface treatment for metals developed at TWI, Surfi-Sculpt™ leads to the formation of surface protrusions on metal surfaces. These protrusions are typically 1.0 mm high and 0.6 mm diameter. The surface modified metal can be bonded with composite laminates to form a Comeld™ joint. These joints can be described as a combination of mechanical fastening and adhesive bonding. There are many possible variables which could be applied to the metal surface. The variables include the shape, height, orientation and distribution (distribution pattern and density) of the protrusions. The aim of this work was to optimise the protrusions with respect to their geometry and distribution using the finite element modelling method for the Comeld™ joint under tensile loading with titanium alloy and cross-ply carbon prepreg composites. The simulations require multi-scale modelling techniques to transfer results between the global model, which is the reflection of the whole joint, and the unit cell models containing a protrusion. The two-dimensional simulations focused on the protrusion geometric parameters whereas the three-dimensional simulations focused on the protrusion spatial arrangement including the distribution pattern and density. Modelling of the entire joint geometry with two and three-dimensional global models was carried out using smeared properties for the adhesive layer which includes the protrusions. These models yield results for both quasi-static properties and stress distributions for these joints. Results from the simulations show critical effects on stress distributions arising from changing protrusion geometry. These joints show significant advantages over conventional joining technologies and their application would allow improved performance for combinations of metal and composite laminates.
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Mulumbwa, Sebe Stanley. "Humanoid Arm Geometric Model." Thesis, Högskolan i Gävle, Avdelningen för elektronik, matematik och naturvetenskap, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-21769.
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The world is slowly moving into increased human-robot interaction where both humans and robots can co-exist in the same domain. For the robot to be able to operate effectively in a man’s designed environment, it becomes necessary to model the robot with human capabilities as humans are seen as more capable. Replicating human becomes a huge challenge due to numerous degrees-of-freedom (DOFs) that human possess resulting into too many variables and nonlinear equations. Other challenges do occur like singularities. In this thesis, the singularity challenge of a redundant humanoid arm is explored while maintaining a simple 7 DOF serial chain structure. As opposed to the 30 DOF human arm, a simpler 7 DOF humanoid arm is adopted and studied to eliminate the singularity challenges. The singularity problem mainly comes from the elbow and the spherical joints at the shoulder and wrist. A step-by-step review of available inverse kinematics techniques is made with more focus on the iterative Jacobian-based methods. A step-by-step approach is adopted so as to identify the source of singularities while using the iterative Jacobian-based techniques that are able to handle the nonlinearities of the equations. The Singular Value Filtering (SVF) technique coupled with Selectively Damped Least Squares (SDLS) is employed. Without any restrictions to the stretch of the arm or end-effector pose, the method demonstrates, in conjunction with Euler angle singularity avoidance method, the elimination of singularity problems. This is achieved with no adjustment to kinematic model of the manipulator.
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Karhnak, Stephen J. "Predicting mechanical performance of adhesively bonded joints based on acousto-ultrasonic evaluation and geometric weighting." Thesis, This resource online, 1994. http://scholar.lib.vt.edu/theses/available/etd-05022009-040452/.
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Satouri, Jamil. "Méthode d'éléments spectraux avec joints pour des géométries axisymétriques." Phd thesis, Université Pierre et Marie Curie - Paris VI, 2010. http://tel.archives-ouvertes.fr/tel-00815022.
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Dans cette thèse on s'est intéressé aux problèmes tridimensionnels de Laplace et de stokes dans des domaines axisymétriques. Ces problèmes sont réduits, sans approximation et par des développements en coefficients de Fourier en une famille dénombrable de problèmes bidimensionnels. Les domaines qu'on a considéré présentent des singularités géométriques et sont décomposés de façons non nécessairement conformes. Les non conformités sur les interfaces entre les sous domaines sont traités par la méthode des joints. La méthode de base de discrétisation est la méthode spectrale. On a montre alors des résultats d'approximation optimaux, proches de ceux trouves lors de l'approximation conformes avec des contraintes de continuités sur les interfaces. Ceci prouve encore une fois l'efficacité de la méthode des joints.
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Björlenstam, Philip. "Evaluation of corrosion in crevices in screw joints." Thesis, KTH, Korrosionslära, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-40473.
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In this Master of Science thesis screws with different coatings were exposed to an accelerated corrosion test in order to investigate the corrosion development. The test matrix constituted of hexagonal and flange screws (fastened on frames) coated with either zinc/iron (ZnFe) or a flake system of aluminum and zinc (GEOMET). The corrosion results were analyzed by means of X-ray diffraction (XRD). In this study the screws were also crosscut and analyzed by means of FEG-SEM in order to determine the thickness and the elemental content of the surface coating. The result of the corrosion test showed that the screws coated with GEOMET showed a very good corrosion resistance whilst the screws coated with ZnFe failed to fulfill the demands on corrosion resistance of Scania.
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Bills, Paul J. "The development of a geometric methodology for the determination of volumetric wear in total joint replacements & development of a total knee replacement joint using new and novel measurement techniques." Thesis, University of Huddersfield, 2007. http://eprints.hud.ac.uk/id/eprint/2020/.
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Total joint replacement is one of the most common elective surgical procedures performed worldwide, with an estimate of 1.5 million operations performed annually. It has long been recognised that wear analysis of total joint replacements is an important means in determining failure mechanisms, functionality and improving longevity of these devices. The standardised method for assessing wear volumes in such joints is through gravimetric means and it has been shown that this method is a useful tool for indicating simulated wear volumes. This method is, however, of little value when considering the case of a clinically explanted bearing surface for which, by definition, there is no ‘pre-wear’ data. The purpose of this thesis is to present a co-ordinate measuring machine (CMM) based technique for assessing the volumetric material loss in total joint replacement joints and to establish its effectiveness. To this end uncertainty calculations are completed for the specific case of orthopaedic component measurement. In this thesis methods have been developed in this thesis for measurement of in vitro wear of total knee replacement bearings and a number of knee joint simulator tests have been completed and their results discussed. An initial test investigating the possible use of metal-on-metal bearings for total knee replacement is described. A test profile for simulation of deep squat is developed, a simulator test completed and the results discussed. An adapted version of the developed CMM measurement method is further adapted and developed for measurement of clinical wear from retrieved bearings and the implications of this capability are examined and discussed. In tandem with this methods are developed for the mapping of wear location and component form deviation and the implications that this has for manufacturing control and wear potential is discussed at length. Overall future developments and work are explored.
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GRITAI, ALEXEI. "MULTI-VIEW GEOMETRIC CONSTRAINTS FOR HUMAN ACTION RECOGNITION AND TRACKING." Doctoral diss., University of Central Florida, 2007. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4032.
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Human actions are the essence of a human life and a natural product of the human mind. Analysis of human activities by a machine has attracted the attention of many researchers. This analysis is very important in a variety of domains including surveillance, video retrieval, human-computer interaction, athlete performance investigation, etc. This dissertation makes three major contributions to automatic analysis of human actions. First, we conjecture that the relationship between body joints of two actors in the same posture can be described by a 3D rigid transformation. This transformation simultaneously captures different poses and various sizes and proportions. As a consequence of this conjecture, we show that there exists a fundamental matrix between the imaged positions of the body joints of two actors, if they are in the same posture. Second, we propose a novel projection model for cameras moving at a constant velocity in 3D space, \emph cameras, and derive the Galilean fundamental matrix and apply it to human action recognition. Third, we propose a novel use for the invariant ratio of areas under an affine transformation and utilizing the epipolar geometry between two cameras for 2D model-based tracking of human body joints. In the first part of the thesis, we propose an approach to match human actions using semantic correspondences between human bodies. These correspondences are used to provide geometric constraints between multiple anatomical landmarks ( e.g. hands, shoulders, and feet) to match actions observed from different viewpoints and performed at different rates by actors of differing anthropometric proportions. The fact that the human body has approximate anthropometric proportion allows for innovative use of the machinery of epipolar geometry to provide constraints for analyzing actions performed by people of different anthropometric sizes, while ensuring that changes in viewpoint do not affect matching. A novel measure in terms of rank of matrix constructed only from image measurements of the locations of anatomical landmarks is proposed to ensure that similar actions are accurately recognized. Finally, we describe how dynamic time warping can be used in conjunction with the proposed measure to match actions in the presence of nonlinear time warps. We demonstrate the versatility of our algorithm in a number of challenging sequences and applications including action synchronization , odd one out, following the leader, analyzing periodicity etc. Next, we extend the conventional model of image projection to video captured by a camera moving at constant velocity. We term such moving camera Galilean camera. To that end, we derive the spacetime projection and develop the corresponding epipolar geometry between two Galilean cameras. Both perspective imaging and linear pushbroom imaging form specializations of the proposed model and we show how six different ``fundamental" matrices including the classic fundamental matrix, the Linear Pushbroom (LP) fundamental matrix, and a fundamental matrix relating Epipolar Plane Images (EPIs) are related and can be directly recovered from a Galilean fundamental matrix. We provide linear algorithms for estimating the parameters of the the mapping between videos in the case of planar scenes. For applying fundamental matrix between Galilean cameras to human action recognition, we propose a measure that has two important properties. First property makes it possible to recognize similar actions, if their execution rates are linearly related. Second property allows recognizing actions in video captured by Galilean cameras. Thus, the proposed algorithm guarantees that actions can be correctly matched despite changes in view, execution rate, anthropometric proportions of the actor, and even if the camera moves with constant velocity. Finally, we also propose a novel 2D model based approach for tracking human body parts during articulated motion. The human body is modeled as a 2D stick figure of thirteen body joints and an action is considered as a sequence of these stick figures. Given the locations of these joints in every frame of a model video and the first frame of a test video, the joint locations are automatically estimated throughout the test video using two geometric constraints. First, invariance of the ratio of areas under an affine transformation is used for initial estimation of the joint locations in the test video. Second, the epipolar geometry between the two cameras is used to refine these estimates. Using these estimated joint locations, the tracking algorithm determines the exact location of each landmark in the test video using the foreground silhouettes. The novelty of the proposed approach lies in the geometric formulation of human action models, the combination of the two geometric constraints for body joints prediction, and the handling of deviations in anthropometry of individuals, viewpoints, execution rate, and style of performing action. The proposed approach does not require extensive training and can easily adapt to a wide variety of articulated actions.<br>Ph.D.<br>School of Electrical Engineering and Computer Science<br>Engineering and Computer Science<br>Computer Science PhD
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Haag, Jefferson. "Influência da geometria do corpo de prova e do tamanho de trinca na tenacidade à fratura do aço API 5DP tool joint." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2015. http://hdl.handle.net/10183/116623.
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Ensaios de mecânica da fratura utilizando corpos de prova padronizados apresentam alto nível de restrição à deformação plástica na ponta da trinca, devido a esforços de flexão e a trincas profundas. Em decorrência do emprego desses corpos de prova, há um alto conservadorismo nos resultados obtidos por esses ensaios, quando aplicados em materiais de boa tenacidade. Aplicações cujos defeitos estão submetidos a baixos níveis de constricção e a pequenas margens de segurança fazem com que sejam necessários corpos de prova mais próximos do estado de tensão submetido pela estrutura para realizar adequadamente a análise crítica de engenharia (Engineering Critical Analysis - ECA). Este trabalho visa analisar a influência da geometria de corpos de prova e do tamanho da trinca na tenacidade à fratura do aço API 5DP Tool Joint. Este estudo constitui-se da realização de ensaios de tenacidade à fratura com duas geometrias de corpos de prova (SE(B) e SE(T)) e quatro tamanhos de trinca normalizados (a0/W = 0,40; 0,50; 0,60; e 0,70) com a técnica da flexibilidade no descarregamento (unloading compliance). Foi utilizado o projeto de experimentos (DOE) para obter resultados referentes aos efeitos principais dos dois fatores e de suas interações. Foram calculadas, a partir de triplicatas para cada condição, curvas de resistência e valores únicos de tenacidade à fratura (Integral J e CTOD), sendo que o último foi utilizado para o cálculo da análise de variância (ANOVA). Com base nos resultados obtidos, conclui-se que a geometria de corpo de prova, tamanho da trinca e a interação entre os dois fatores possuem efeito significativo sobre as variáveis resposta (CTOD e Integral J) com nível de significância de 5%. Além disso, obtiveram-se os valores de JIC e δi através das curvas de resistência, mostrando que esses valores independem da geometria e do tamanho da trinca.<br>Fracture mechanics testing using standardized specimens have a high level of restriction to plastic deformation at the crack tip, due the bending stresses and deep crack lengths. Due to the use of these specimens geometry, there is a high conservatism on the obtained results of fracture toughness testing when applied on high toughness materials. The application of specimens closely modeling to the actual stress conditions in the component under consideration are necessary to evaluate structures containing defects with low levels of constraint and small safety margins to perform appropriately the engineering critical analysis (ECA). This work aims to analyze the influence of specimen geometry and crack length on the fracture toughness of API 5DP Tool Joint steel. This study consists in the execution of fracture toughness testing on two specimen geometries (SE(B) e SE(T)) and four normalized crack lengths (a0/W = 0,40; 0,50; 0,60; and 0,70) with the unloading compliance method. Design of experiments (DOE) was applied to obtain results regarding to the main factors effects and their interactions. From triplicates of each condition, resistance curves and unique values of fracture toughness (J integral and CTOD) were calculated, and the latter result was used to calculate the analysis of variance (ANOVA). The obtained outcomes show that the specimen geometry, crack length and the interaction between these factors have significant effect on the response variables (CTOD and J integral) on a significance level of 5%. In addition, there were obtained the values of JIC e δi through the resistance curves, showing that these values do not depend on the geometry and crack length.
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Roy, Samit. "A finite element analysis of adhesively bonded composite joints including geometric nonlinearity, nonlinear viscoelasticity, moisture diffusion and delayed failure." Diss., Virginia Polytechnic Institute and State University, 1987. http://hdl.handle.net/10919/88624.
Full textAbstract:
A two-dimensional finite-element computational procedure is developed for the accurate analysis of the strains and stresses in adhesively bonded joints. The large displacements and rotations experienced by the adherends and the adhesive are taken into account by invoking the updated Lagrangian description of motion. The adhesive layer is modeled using Schapery's nonlinear single integral constitutive law for uniaxial and multiaxial states of stress. Effect of temperature and stress level on the viscoelastic response is taken into account by a nonlinear shift factor definition. Penetrant sorption is accounted for by a nonlinear Fickean diffusion model in which the diffusion coefficient is dependent on the penetrant concentration and the dilatational strain. A delayed failure criterion based on the Reiner-Weisenberg failure theory has also been implemented in the finite element code. The applicability of the proposed models is demonstrated by several numerical examples.<br>Doctor of Philosophy
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Marchi, Tommaso. "Position and singularity analysis of a class of n-RRR planar parallel robots." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2020.
Find full textAbstract:
Parallel robots with configurable platform are a class of parallel robots in which the end-effector is a closed-loop flexible chain of rigid links. We have developed a 5-RRR planar mechanism that features a flexible 5-bar chain as end-effector. The angles between adjacent sides of this chain can be controlled through the actuated revolute joints attached to the base of the mechanism. This thesis consists in the geometrical design of n-RRR planar parallel robots and in the study of the Direct Kinematics for 4-, 5- and 6-RRR mechanisms using Bilateration, a method that greatly reduces the computational time for the kinematic analysis. The next step is the singularity analysis for the n-RRR robot architectures; finally, in the last part of this thesis we present the results from experimental tests that have been performed on a 5-RRR robot prototype.
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Serrano, Luisa Julieth Parra. "Resistência à tração da madeira e resistência ao cisalhamento no plano de cola, seus impactos na geometria do dente e propriedades mecânicas de emendas dentadas." Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/11/11150/tde-14042009-111712/.
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A presente pesquisa teve como objetivo estudar a resistência ao cisalhamento no plano de cola de corpos de prova especiais e avaliar o seu impacto na geometria do dente, na resistência à tração de emendas dentadas e nas propriedades oriundas da flexão de vigas simples e compostas. A resistência ao cisalhamento no plano de cola foi estudada segundo o seu ângulo de inclinação em relação às fibras, desde 0 até 90o na madeira de Eucalyptus grandis e Pinus elliottii. O Eucalyptus grandis foi favorecido por pequenos ângulos de inclinação do plano de cola contrariamente ao que aconteceu com o Pinus elliottii e, portanto, apresentou maior eficiência na colagem, o que é desejável para viga laminada colada. Os valores obtidos foram divididos pela resistência ao cisalhamento da madeira maciça para encontrarem-se as eficiências das ligações coladas com vários adesivos. O valor da resistência ao cisalhamento no ângulo de 5° foi utilizado conjuntamente com a resistência à tração da madeira maciça de Eucalyptus grandis para calcular o comprimento do dente a partir de uma teoria simples que o relaciona aos demais parâmetros já conhecidos ou simulados da emenda dentada. Essa teoria, resumida numa única identidade, foi desenvolvida para otimizar a emenda em termos de seus esforços solicitantes majoritários.A emenda dentada foi testada à tração paralela em lâminas emendadas com dentes verticais e horizontais. O perfil vertical apresentou maior resistência à tração e a diferença foi explicada pela área de colagem individual do dente. No caso do dente vertical essa área era menor e, portanto, penalizava menos quando havia algum defeito no dente. Na análise dos tipos de ruptura apresentados verificou-se que a ruptura do tipo 1 que denota má colagem por causa intrínseca do adesivo ou falta de pressão na colagem e ruptura do tipo 5 ou 6 que evidenciam pontos excessivamente fracos da barra ligada ou pontos de concentração de tensões imposta pelas garras da máquina no ensaio de tração contribuíam significativamente para redução da resistência à tração da emenda dentada. Essa resistência deve ser caracterizada por ocorrência alternada de rupturas por cisalhamento misto na superfície do dente e ruptura por tração na seção reduzida da barra ou na raiz do dente como acontece na ruptura do tipo 3. Na flexão foram ensaiadas lâminas emendadas trabalhando como viga sujeita a tensões normais de tração e de compressão e lâminas emendadas trabalhando como componente de viga laminada posicionada na borda tracionada. Não houve diferença entre esses dois casos em qualquer dos estados limites. A eficiência da viga laminada colada com emenda no meio do vão foi muito baixa em relação à viga maciça, mas somente para o módulo de ruptura à flexão. Essa eficiência foi expressa como a relação entre o momento de inércia real e o teórico. A emenda dentada não influenciou a elástica da viga laminada que apresentou o mesmo módulo de elasticidade da viga maciça.<br>The objective of the present study was to determine the shear strength in the bonding surface of special samples and to evaluate their impact on the geometric parameters of the finger, the tensile strength of the finger joints and the intrinsic flexural properties of simple and composed beams. The shear strength on the bonding surface was studied as a function of the inclination angle related to the wood fibers direction, from 0 to 90o in Eucalyptus grandis and Pinus elliottii species. Small inclination angles of the bonding surface performed very well in E. grandis samples and therefore it showed higher bonding efficiency when compared to P. Elliottii. The efficiency of the glued joints with different adhesives was determined by dividing the measured values by the shear strength of the solid wood. A simple theory relates the other known or simulated parameters of finger joints to the length of the finger. Using the values of the shear strength obtained experimentally with an inclination angle of 5o and the tensile strength of the solid wood of E. grandis finger length was calculated. Such theory, summarized in a unique equality, was developed to optimize the finger joints in terms of major acting efforts. The finger joints which had vertical and horizontal finger were tested in parallel traction to evaluate the maximum carrying load. The vertical profile had higher tensile strength and the difference was explained by the area of the glued joints in the finger. In the case of the vertical finger the area of glued joints was smaller and therefore had less impact when there was a defect in the finger or problem with the adhesion. Analyses of the modules of rupture revealed that rupture type 1 and type 5 or 6 contributed significantly to the reduction in the tensile strength of the finger joints. Rupture type 1 refers to failure due to causes intrinsic to the adhesive or to lack of pressure in the bonding process. Rupture type 5 or 6 refers to the presence of excessively weak points in the bar or to points of concentration of stress imposed by the clamps of the machine during the test. Such tensile strength must be characterized by the alternate presence of ruptures by mixed shear strength in the surface of the finger tip and the rupture by traction in the reduced section of the bar or in the base of the finger tip similar to a type 3 rupture. In flexural tests laminas which had a finger joint in the middle of the span ware tested as a beam subjected to tensile and compression normal stresses and also as a component of the laminated beam located in the traction edge. There were no significant differences between these two cases in any of the limiting states. The efficiency of the glued laminated beam with the finger joints located in the middle of the distance among points of support was very low in relationship to the efficiency of the solid wood, but only for the modulus of rupture in the flexure. This efficiency was expressed as the ratio of the moment of inertia to the theoretical moment. The finger joint did not influence the elasticity of the laminated beam since it had the same modulus of elasticity as the one found for solid wood.
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Rýdel, Jiří. "Deformačně napěťová analýza TEP kyčelního kloubu – typ Mayo." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2008. http://www.nusl.cz/ntk/nusl-378907.
Full textAbstract:
This diploma thesis deals with hip endoprothesis, primarily with endoprothesis conservative Mayo. A part of this paper considers a study aimed at an anatomy, types and modern trends in endoprothetic. On the basis of this study, gained CT data and the help of systems Ansys Workbench, Rhino Ceros and Catia there was made a model of proximal part of femur and TEP Conservative Mayo. A computational model was build up afterwards, which was used for a stress-train analysis.
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Congedo, Marco. "EEG Source Analysis." Habilitation à diriger des recherches, Université de Grenoble, 2013. http://tel.archives-ouvertes.fr/tel-00880483.
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Electroencephalographic data recorded on the human scalp can be modeled as a linear mixture of underlying dipolar source generators. The characterization of such generators is the aim of several families of signal processing methods. In this HDR we consider in several details three of such families, namely 1) EEG distributed inverse solutions, 2) diagonalization methods, including spatial filtering and blind source separation and 3) Riemannian geometry. We highlight our contributions in each of this family, we describe algorithms reporting all necessary information to make purposeful use of these methods and we give numerous examples with real data pertaining to our published studies. Traditionally only the single-subject scenario is considered; here we consider in addition the extension of some methods to the simultaneous multi-subject recording scenario. This HDR can be seen as an handbook for EEG source analysis. It will be particularly useful to students and other colleagues approaching the field.
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Aristidou, Andreas. "Tracking and modelling motion for biomechanical analysis." Thesis, University of Cambridge, 2010. https://www.repository.cam.ac.uk/handle/1810/237554.
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This thesis focuses on the problem of determining appropriate skeletal configurations for which a virtual animated character moves to desired positions as smoothly, rapidly, and as accurately as possible. During the last decades, several methods and techniques, sophisticated or heuristic, have been presented to produce smooth and natural solutions to the Inverse Kinematics (IK) problem. However, many of the currently available methods suffer from high computational cost and production of unrealistic poses. In this study, a novel heuristic method, called Forward And Backward Reaching Inverse Kinematics (FABRIK), is proposed, which returnsvisually natural poses in real-time, equally comparable with highly sophisticated approaches. It is capable of supporting constraints for most of the known joint types and it can be extended to solve problems with multiple end effectors, multiple targets and closed loops. FABRIK wascompared against the most popular IK approaches and evaluated in terms of its robustness and performance limitations. This thesis also includes a robust methodology for marker prediction under multiple marker occlusion for extended time periods, in order to drive real-time centre of rotation (CoR) estimations. Inferred information from neighbouring markers has been utilised, assuming that the inter-marker distances remain constant over time. This is the firsttime where the useful information about the missing markers positions which are partially visible to a single camera is deployed. Experiments demonstrate that the proposed methodology can effectively track the occluded markers with high accuracy, even if the occlusion persists for extended periods of time, recovering in real-time good estimates of the true joint positions. In addition, the predicted positions of the joints were further improved by employing FABRIK to relocate their positions and ensure a fixed bone length over time. Our methodology is tested against some of the most popular methods for marker prediction and the results confirm that our approach outperforms these methods in estimating both marker and CoR positions. Finally, an efficient model for real-time hand tracking and reconstruction that requires a minimumnumber of available markers, one on each finger, is presented. The proposed hand modelis highly constrained with joint rotational and orientational constraints, restricting the fingers and palm movements to an appropriate feasible set. FABRIK is then incorporated to estimate the remaining joint positions and to fit them to the hand model. Physiological constraints, such as inertia, abduction, flexion etc, are also incorporated to correct the final hand posture. A mesh deformation algorithm is then applied to visualise the movements of the underlying hand skeleton for comparison with the true hand poses. The mathematical framework used for describing and implementing the techniques discussed within this thesis is Conformal GeometricAlgebra (CGA).
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Chen, Hao Wei, and 陳浩瑋. "Influence of Molding Parameters and Joint Geometry on Adhesion Strength." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/66a9bu.
Full textAbstract:
碩士<br>國立虎尾科技大學<br>機械與電腦輔助工程系碩士班<br>100<br>In this work, the adhesion strength of insert molding with two types of joint geometry is studied. The material used is Acrylonitrile Butadiene Styrene (ABS) and the main different of the joint geometry are the contact angles, which are 90°and 75°, respectively. The specimen dimension is designed according to the ASTM-D25 Standard. The influence of injection parameters such as injection speed, holding pressure, holding time, etc. on the adhesion strength of insert molding are investigated through the Taguchi method. In addition, the effects of the different factors are also studied by ANOVA approach. In order to examine the influence of the melt viscosity variation in injection molding, a pressure sensor is installed in the cavity to calculate the melt viscosity by the injection pressure data. The data shows that a higher mold temperature can enhance the adhesion strength for both contact angles but only a higher injection speed is good for the 90 ° contact angle of joint geometry. The experiment for investigating the influence of different melt viscosities on the adhesion strength of insert molding is also implemented. The result also agree that the previous result calculated by Taguchi method.
Keywords：insert
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Yuan, Shi-Zhe, and 袁士哲. "A Study on the Geometry and Mechanical Properties of Hybrid Joint." Thesis, 1998. http://ndltd.ncl.edu.tw/handle/72441978079004618959.
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Yuan, Shih-Che, and 袁士哲. "A Study on the Geometry and Mechanical Properties of Hybrid Joint." Thesis, 1998. http://ndltd.ncl.edu.tw/handle/27714095314140789094.
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碩士<br>國立臺灣大學<br>土木工程學系研究所<br>86<br>Hybrid joint proposed by Hancock in 1985 belongs to a kind of extensional
-shear fracture which mechanism is between shear fracture governed by Coulomb'
stheory and tensile fracture by Griffith's theory. On the study of hybrid join
t, Kuo and Huang conducted a series of tensile-compression tests to simulateth
e mechanical conditions for hybrid joint in the laboratory, and proved itsexis
tency. Chen discussed the relationship between geometry of hybrid joint andstr
ess field induced by fold according to joint field survey as well as FEMnumeri
cal simulation result. This research is divided into three parts: physical
model test in thelaboratory, model analysis and field survey. Physical experim
ent-tensile-compression test- simulates the stress conditions for hybrid fract
ure usingservo-controlled stiff machine. Specimen size is also considered in o
rder toextend the range of tensile stresses hoping for the complete stress fai
lureenvelope in the tensile stress zone. A model is constructed for rock fract
ureunder three dimensional stress strain conditions according to polyaxialexpe
riment data in different stress zone by Kuo, Huang and Reches. Fieldsurvey foc
uses on the correspondence between hybrid joint and other geologicalstructures
. Experiment results show that sandstone is fractured into three patterns:c
onjugate hybrid fracture, vertical extension fracture and singly-inclinedfract
ure. Fracture is plotted as great circles and poles by equal areaprojection, a
nd can be recognized as the pattern of steep, small dihedralangle in the direc
tion of maximum principle stress. Dihedral angle approximatelydecreases as the
minimum principle stress also decreases. In two dimensionalstress space, Grif
fith failure criterion underestimates the strength butoverestimates the dihedr
al angle; regressed Hoek-Brown and Mohr-Coulomb failurecriterion parameter are
obviously deviated for tests under different stresspaths. In three dimensiona
l stress space, there is accorded trend for thetensile-compression test data a
nd thus three dimensional failure envelope isconstructed by method of normaliz
ation. Fracture patterns are also includedin this envelope to explain the stre
ss state inducing hybrid fracture andorthorhombic fracture. Field joint data r
eveal that strikes of joints are roughlyperpendicular to the strike of anticli
ne in both cases of study and areindicators of contemporary stress field cause
d by geological changes.