We present a solution to animating interactions between characters and thin, non-rigid bodies using a passive optical motion capture system. Prior work in human body motion capture can accurately recreate human motion but this work is not adequate because it does not allow for interactions with a non-rigid body. Prior work in face and cloth motion capture handles non-rigid planes but rope is better handled with a curved spline rather than a curved plane. The segmented motion is in the form of un-indexed motion capture data. After segmenting the motion of the thin, non-rigid body and the human character the separated motion capture data can be recreated individually. The recreated motion streams are then recombined using 3D modeling and animation software. The presented solution also improves techniques for recreating thin, non-rigid body motion from un-indexed motion capture data. Using the linear combination of two predicted marker positions our solution can accurately track motion capture markers through each frame of the motion capture data. This also allows our solution to invent marker positions when gaps are present in the motion capture data. Our improvements allow users to reconstruct the motion of both a human character and a thin, non-rigid body simultaneously from motion capture data gathered in a mixed motion capture session.

This research presents a procedure for interactive segmentation and automatic tracking of moving objects in a video sequence. The user outlines the region of interest (ROI) in the initial frame; the procedure builds a refined mask of the dominant object within the ROI. The refined mask is used to model a spline template of the object to be tracked. The tracking algorithm then employs a motion model to track the template through a sequence of frames and gathers the 3D affine motion parameters of the object from each frame. The extracted template is compared with a previously stored library of 3D shapes to determine the closest 3D object. If the extracted template is completely new, it is used to model a new 3D object which is added to the library. To recreate the motion, the motion parameters are applied to the 3D object in a virtual environment. The procedure described here can be applied to industrial problems such as traffic management and material flow congestion analysis.

Many bridges are damaged by collisions from over-height vehicles resulting in significant impact to the transportation network. To reduce the likelihood of impact from over-height vehicles, steel pedestals have been used as a cost-effective, efficient means to increase bridge clearance heights. However, these steel pedestals installed on more than 50 bridges in Georgia have been designed with no consideration of seismic loads and may behave in a similar fashion to high-type steel bearings. Past earthquakes have revealed the susceptibility of high-type bearings to damage, resulting in the collapse of several bridges. Although Georgia is located in a low-to-moderate region of seismicity, earthquake design loads for steel pedestals should not be ignored. In this study, the potential vulnerabilities of steel pedestals having limited strength and deformation capacity and lack of adequate connection details for anchor bolts is assessed experimentally and analytically. Full-scale reversed cyclic quasi-static experimental tests are conducted on a 40' bridge specimen rehabilitated with 19" and 33" steel pedestals to determine the modes of deformation and mechanisms that can lead to modes of failure. The inelastic force-deformation hysteretic behavior of the steel pedestals obtained from experimental test results is used to calibrate an analytical bridge model developed in OpenSees. The analytical bridge model is idealized based on a multi-span continuous bridge in Georgia that has been rehabilitated with steel pedestals. The analytical bridge model is subjected to a suite of ground motions to evaluate the performance of the steel pedestals and the overall bridge system. Recommendations are made to the Georgia Department of Transportation (GDOT) for the design and construction of steel pedestals. The results of this research are useful for Georgia and other states in low-to-moderate seismic zones considering the use of steel pedestals to elevate bridges and therefore reduce the likelihood of over-height vehicle collisions.

This research presents a procedure for interactive segmentation and automatic tracking of moving objects in a video sequence. The user outlines the region of interest (ROI) in the initial frame; the procedure builds a refined mask of the dominant object within the ROI. The refined mask is used to model a spline template of the object to be tracked. The tracking algorithm then employs a motion model to track the template through a sequence of frames and gathers the 3D affine motion parameters of the object from each frame. The extracted template is compared with a previously stored library of 3D shapes to determine the closest 3D object. If the extracted template is completely new, it is used to model a new 3D object which is added to the library. To recreate the motion, the motion parameters are applied to the 3D object in a virtual environment. The procedure described here can be applied to industrial problems such as traffic management and material flow congestion analysis.

No description available.

The nonlinear interactions between aerodynamic forces and wing structures are numerically investigated as integrated dynamic systems, including structural models, aerodynamics, and control systems, in the time domain. An elastic beam model coupled with rigid-body rotation is developed for the wing structure, and the natural frequencies and mode shapes are found by the finite-element method. A general unsteady vortex-lattice method is used to provide aerodynamic forces. This method is verified by comparing the numerical solutions with the experimental results for several cases; and thereafter applied to several applications such as the inboard-wing/twin-fuselage configuration, and formation flights. The original thought that the twin fuselage could achieve two-dimensional flow on the wing by eliminating free wing tips appears to be incorrect. The numerical results show that there can be a lift increase when two or more wings fly together, compared to when they fly alone. Flutter analysis is carried out for a High-Altitude-Long-Endurance aircraft wing cantilevered from the wall of the wind tunnel, a full-span wing mounted on a free-to-roll sting at its mid-span without and with a center mass (fuselage). Numerical solutions show that the rigidity added by the wall results in a higher flutter speed for the wall-mounted semi-model than that for the full-span model. In addition, a predictive control technique based on neural networks is investigated to suppress flutter oscillations. The controller uses a neural network model to predict future plant responses to potential control signals. A search algorithm is used to select the best control input that optimizes future plant performance. The control force is assumed to be given by an actuator that can apply a distributed torque along the spanwise direction of the wing. The solutions with the wing-tip twist or the wing-tip deflection as the plant output show that the flutter oscillations are successfully suppressed with the neural network predictive control scheme. / Ph. D.

視覺追蹤(visual tracking)一直是傳統電腦視覺研究中相當重要的議題，許多電腦視覺的應用都需要結合視覺追蹤的幫助才能實現。近年來擴增實境(augmented reality)能快速成功的發展，均有賴於視覺追蹤技術上之精進。擴增實境採用視覺追蹤的技術，可將虛擬的物件呈現在被追蹤的物體(真實場景)上，進而達成所需之應用。 由於在視覺追蹤上，被追蹤之物體易受外在環境因素影響，例如位移、旋轉、縮放、光照改變等，影響追蹤結果之精確度。本研究中，我們設計了一套全新的圖形標記方法作為視覺追蹤之參考點，能降低位移、旋轉與光照改變所造成追蹤結果的誤差，也能在複雜的背景中定位出標記圖形的正確位置，提高視覺追蹤的精確度。同時我們使用立體視覺追蹤物體，將過去只使用單一攝影機於二維影像資訊的追蹤問題，提升至使用三維空間的幾何資訊來做追蹤。然後透過剛體(rigid)特性找出旋轉量、位移量相同的物件，並且結合一致性隨機取樣(random sample consensus)之技巧以估測最佳的剛體物件運動模型，達到強健性追蹤的目的。 另外，我們可由使用者提供之影片資訊中擷取特定資料，透過建模技術將所產生之虛擬物件呈現於使用者介面(或被追蹤之物體)上，並藉由這些虛擬物件，提供真實世界外之資訊，達成導覽指引(或擴增實境)的效果。 實驗結果顯示，我們的方法具有辨識時間快、抗光照變化強、定位準確度高的特性，適合於擴增實境應用，同時我們設計的標記圖形尺寸小，方便適用於導覽指引等應用。 / Visual tracking is one of the most important research topics in traditional computer vision. Many computer vision applications can not be realized without the integration of visual tracking techniques. The fast growing of augmented reality in recent years relied on the improvement of visual tracking technologies. External environment such as object displacement, rotation, and scaling as well as illumination conditions will always influence the accuracy of visual tracking. In this thesis, we designed a set of markers that can reduce the errors induced by the illumination condition changes as well as that by the object displacement, rotation, and scaling. It can also correctly position the markers in complicated background to increase the tracking accuracy. Instead of using single camera tracking in 2D spaces, we used stereo vision techniques to track the objects in 3D spaces. We also used the properties of rigid objects and search for the objects with the same amount of rotation and displacement. Together with the techniques of random sample consensus, we can estimate the best rigid object motion model and achieve tracking robustness. Moreover, from the user supplied video, we can capture particular information and then generate the virtual objects that can be displaced on the user’s device (or on the tracked objects). Using these techniques we can either achieve navigation or guidance in real world or achieve augmented reality as we expected. The experimental results show that our mechanism has the characteristics of fast recognition, accurate positioning, and resisting to illumination changes that are suitable for augmented reality. Also, the size of the markers we designed is very small and good for augmented reality application.

No description available.

Tesis por compendio / [ES] El ruido de rodadura de vehículos ferroviarios presenta importantes desafíos en entornos urbanos y suburbanos, siendo precisa una comprensión integral de sus mecanismos subyacentes para una mitigación efectiva. Esta Tesis ofrece una investigación exhaustiva sobre la generación de ruido de rodadura, tanto en vías rectas como curvas, a través del desarrollo de modelos avanzados de alta frecuencia y herramientas de cálculo para una rigurosa predicción de niveles de ruido. El ruido de rodadura surge de la interacción entre las ruedas y los carriles en presencia de imperfecciones en sus superficies de contacto. Los principales componentes ferroviarios que contribuyen a la emisión acústica son las traviesas, los carriles y las ruedas. Las traviesas y los carriles están conectados por medio de las placas de asiento, mientras que las ruedas y los carriles están dinámicamente acoplados a través de su contacto. En consecuencia, cambios en cualquier componente pueden afectar al comportamiento dinámico y acústico del resto, subrayando la necesidad de un modelo integral para abordar eficazmente la radiación por ruido de rodadura. En esta Tesis se exploran y desarrollan diferentes modelos dinámicos de la vía y del eje montado. La vía, que se asume infinita, se describe utilizando la teoría de estructuras periódicas y se caracteriza por sus números y formas de onda. El eje montado se modeliza mediante el Método de Elementos Finitos y se caracteriza por sus frecuencias naturales y modos de vibración. La interacción rueda/carril se describe como una relación linealizada entre el movimiento relativo de ambos componentes y las fuerzas de contacto. Cabe indicar que los modelos explorados en este trabajo están formulados en el dominio de la frecuencia. Asimismo, se realiza un estudio de influencia del diseño de la vía en la radiación por ruido de rodadura, cuantificando los parámetros contribuyentes a la emisión acústica mediante técnicas estadísticas. Los resultados apuntan a que la geometría del carril tiene un impacto limitado en la radiación, mientras que las propiedades viscoelásticas de la vía, en particular la rigidez de la placa de asiento, desempeñan un papel fundamental en la generación de ruido. Es remarcable que, entre los distintos diseños, se han encontrado variaciones de hasta 7,4 dB(A) en la radiación acústica. Durante el desarrollo de esta investigación, se ha prestado atención al modelizado del eje montado. Su rotación se incluye usando coordenadas Eulerianas, lo que resulta un enfoque conveniente ya que el punto de contacto de la rueda con el carril permanece en una posición espacial constante. Dada la simetría axial de su geometría, la respuesta dinámica del eje montado se expande a lo largo de la dirección circunferencial mediante series de Fourier, lo que permite formular el comportamiento dinámico y acústico de este cuerpo tridimensional (3D) en un marco bidimensional (2D), resolviendo analíticamente la coordenada circunferencial. Esta metodología ofrece sin pérdida de generalidad una reducción del tiempo de cálculo computacional, lo que hace que el modelo sea idóneo para su integración en algoritmos de optimización. Por último, se realiza una investigación pionera sobre el ruido de rodadura cuando el vehículo negocia una curva. Si bien la curva está generalmente asociada con el ruido por chirridos, esta Tesis explora y confirma la importancia que también tiene el ruido de rodadura en estas condiciones. Para ello, se modelizan los efectos inerciales y giroscópicos que sufre un eje montado al describir una trayectoria curva. Además, diferentes fenómenos complejos que ocurren en el contacto rueda/carril, como por ejemplo el movimiento relativo entre estos elementos, se incorporan en el modelo de interacción. Los resultados indican que la posición del contacto rueda/carril sirve como un buen indicador del impacto que la negociación de una curva tiene en el ruido de rodadura. / [CA] El soroll de rodament de vehicles ferroviaris presenta importants reptes en entorns urbans i suburbans, requerint una comprensió integral dels seus mecanismes subjacents per a una mitigació efectiva. Aquesta Tesi ofereix una investigació exhaustiva sobre la generació de soroll de rodament, tant en vies rectes com corbes, mitjançant el desenvolupament de models avançats d'alta freqüència i eines de càlcul per a la rigorosa predicció dels nivells de soroll radiat. El soroll de rodament sorgeix de la interacció entre les rodes i els carrils en presència d'imperfeccions en les seues superfícies de contacte. Els principals components ferroviaris que contribueixen a l'emissió acústica són les travesses, els carrils i les rodes. Les travesses i els carrils estan connectats a través de les plaques d'assentament, mentre que les rodes i els carrils estan acoblats mitjançant la seua interacció. En conseqüència, canvis en qualsevol component poden afectar al comportament dinàmic i acústic de la resta, subratllant la necessitat d'un model integral. En aquesta Tesi s'exploren i desenvolupen diversos models dinàmics de la via i de l'eix muntat. La via, que es considera infinita, es descriu utilitzant la teoria d'estructures periòdiques i es caracteritza pels seus números i formes d'ona. L'eix muntat es modelitza mitjançant el Mètode d'Elements Finits i es caracteritza per les seues freqüències naturals i modes de vibració. La interacció entre l'eix muntat i la via es descriu com una relació linealitzada entre el moviment relatiu d'ambdós components i les forces de contacte. Cal assenyalar que els models explorats en aquest treball estan formulats en el domini de la freqüència. Així mateix, es realitza un estudi d'influència del disseny de la via en la radiació, quantificant els paràmetres contribuents a l'emissió acústica mitjançant tècniques estadístiques. Els resultats apunten que la geometria del carril té un impacte limitat en la radiació sonora, mentre que les propietats viscoelàstiques de la via, en particular la rigidesa de la placa d'assentament, tenen un paper fonamental en la generació de soroll. És destacable que, entre els diferents dissenys, s'han trobat variacions de fins a 7,4 dB(A) en la radiació per soroll de rodament. Durant el desenvolupament d'aquesta investigació, s'ha prestat atenció al modelatge de l'eix muntat. La seua rotació s'inclou en la formulació utilitzant coordenades Eulerianes, la qual cosa resulta un enfocament convenient ja que el punt de contacte de la roda amb el carril roman en una posició constant. Donada la simetria axial de la seua geometria, la resposta dinàmica de l'eix muntat s'amplia al llarg de la direcció circumferencial mitjançant sèries de Fourier, permetent formular el comportament dinàmic i acústic d'aquest cos tridimensional (3D) en un marc bidimensional (2D), i resolent la coordenada circumferencial analíticament. Aquesta metodologia ofereix sense pèrdua de generalitat una reducció del temps de càlcul computacional, la qual cosa fa que el model siga idoni per a la seua integració en algoritmes d'optimització. Finalment, es realitza una investigació pionera sobre el soroll de rodament quan el vehicle negocia una corba. Si bé la corba està generalment associada amb el soroll per grinyols, aquesta Tesi explora i confirma la importància que també té el soroll de rodament en aquestes condicions. Per a això, es modelitzen els efectes inercials i giroscòpics que pateix un eix muntat al descriure una trajectòria corba. A més, diferents fenòmens complexes que ocorren en el contacte roda/carril, com el moviment relatiu entre aquests elements, s'incorporen en el model d'interacció. Els resultats indiquen que la posició del contacte roda/carril serveix com un bon indicador de l'impacte que la negociació d'una corba té en el soroll de rodament. / [EN] Rolling noise emission in railway systems presents significant challenges in urban and suburban environments, requiring a comprehensive understanding of its underlying mechanisms for effective mitigation. This Thesis offers a thorough investigation into rolling noise generation, considering both tangent and curved tracks, through the development of advanced high-frequency models and calculation tools to predict noise levels accurately. Rolling noise arises from the interaction between railway wheels and tracks in the presence of roughness on their contact surfaces. The principal components contributing to the acoustic emission are the sleepers, rails, and wheels. Sleepers and rails are interconnected through rail pads, while wheels and rails are dynamically coupled due to their contact. Consequently, changes in any component might impact the dynamic and acoustic behaviour of all of them, outlining the necessity of a comprehensive model to address rolling noise radiation effectively. Various models for the track and wheelset are explored and developed in this Thesis. The track, assumed to be infinite, is described using periodic structure theory and it is characterised by its wavenumbers and waveshapes. The wheelset is modelled through the Finite Element Method (FEM) and it is characterised by its natural frequencies and vibration modes. The wheelset and track interaction is described as a linearised relationship between the relative motion of both components and the contact forces. The models examined in this work are formulated in the frequency domain. Identified track properties influencing rolling noise radiation are quantified using statistical techniques. While the rail geometry is found to have a limited impact on the total radiation, the viscoelastic properties of the track, particularly the rail pad stiffness, play a crucial role in noise generation. Variations up to 7.4 dB(A) were observed for different track designs. Special attention is devoted to the wheelset modelling in this Thesis. Its rotation is considered using Eulerian coordinates, a convenient approach as the wheel contact point with the rail remains at a constant spatial position. Given the axial symmetry of its geometry, the wheelset dynamic response is expanded around the circumferential direction using Fourier series, which yields a two-dimensional (2D) formulation of the dynamic and acoustic behaviour of this three-dimensional (3D) system, with the circumferential coordinate being solved analytically. This methodology, denoted as axisymmetric approach, offers a significant reduction in the associated computational calculation time while preserving accuracy, making the model well suited for its integration into optimisation algorithms. Lastly, a novel investigation into rolling noise when the vehicle negotiates a curve is conducted. While curved tracks are generally associated with squeal noise, this Thesis offers valuable insights into the importance of rolling noise as well. To achieve this, the inertial and gyroscopic effects associated with a wheelset running on a curve are modelled. Complex phenomena occurring at the wheel/rail contact, such as the relative motion between these two elements, are incorporated into the interaction model. The results indicate that the wheel/rail contact position serves as a reliable indicator of the impact of a curve on the rolling noise. / This Thesis has been supported by Ministerio de Ciencia, Innovación y Universidades in the framework of the FPU grant program. Grants FPU18/03999, EST21/00213, and EST22/00353 as well as projects TRA2017-84701-R, PID2020-112886RA-I00, and PID2023-148483OB-I00 funded by MCIN/AEI/10.13039/501100011033, “ESF Investing in your future”, and “ERDF A way of making Europe” are acknowledged. The author also expresses his gratitude for the support provided by Programa PROMETEO/2021/046 of Generalitat Valenciana. / Andrés Ruiz, VT. (2024). Comprehensive dynamic models of railway wheelsets and tracks for the prediction of rolling noise [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/206074 / Compendio