Physics engines have become increasingly prevalent in everyday technology. In the context of this thesis they are regarded as a readily available data set that has the potential to intuitively present the process of sonification to a wide audience. Unfortunately, this process is not the focus of attention when formative decisions are made concerning the continued development of these engines. This may reveal a missed opportunity when considering that the field of interactive sonification upholds the importance of physical causalities for the analysis of data through sound. The following investigation deliberates the contextual framework of this field to argue that the physics engine, as part of typical game engine architecture, is an appropriate foundation on which to design and implement a dynamic toolset for interactive sonification. The basis for this design is supported by a number of significant theories which suggest that the underlying data of a rigid body dynamics physics system can sustain an inherent audiovisual metaphor for interaction, interpretation and analysis. Furthermore, it is determined that this metaphor can be enhanced by the extraordinary potential of the computer in order to construct unique abstractions which build upon the many pertinent ideas and practices within the surrounding literature. These abstractions result in a mental model for the transformation of data to sound that has a number of advantages in contrast to a physical modelling approach while maintaining its same creative potential for instrument building, composition and live performance. Ambitions for both sonification and its creative potential are realised by several components which present the user with a range of options for interacting with this model. The implementation of these components effectuates a design that can be demonstrated to offer a unique interpretation of existing strategies as well as overcoming certain limitations of comparable work.

Computational modeling of joints and their function, a developing field, is becoming a significant health and wellness tool of our modern age. Due to familiarity of prior research focused on the lower extremity, a foot and ankle 3D computational model was created to explore the potential for these computational methods. The method of isolating CT scanned tissue and rendering a patient specific anatomy in the digital domain was accomplished by the use of MIMICS™ , SolidWorks™, and COSMOSMotion™ – all available in the commercial domain. The kinematics of the joints are driven solely by anatomically modeled soft tissue applied to articulating joint geometry. Soft tissues are based on highly realistic measurements of anatomical dimension and behavior. By restricting all model constraints to true to life anatomical approximations and recreating their behavior, this model uses inverse kinematics to predict the motion of the foot under various loading conditions. Extensive validation of the function of the model was performed. This includes stability of the arch (due to ligament deficiency) and joint behavior (due to disease and repair). These simulations were compared to a multitude of studies, which confirmed the accuracy of soft tissue strain, joint alignment, joint contact force and plantar load distribution. This demonstrated the capability of the simulation technique to both qualitatively recreate trends seen experimentally and clinically, as well as quantitatively predict a variety of tissue and joint measures. The modeling technique has further strength by combining measurements that are typically done separate (experimental vs. clinical) to build a more holistic model of foot behavior. This has the potential to allow additional conclusions to be drawn about complications associated with repair techniques. This model was built with the intent to provide an example of how patient specific bony geometry can be used as either a research or surgical tool when considering a disease state or repair technique. The technique also allows for the repeated use of anatomy, which is not possible experimentally or clinically. These qualities, along with the accuracy demonstrated in validation, prove the integrity of the technique along with demonstrating its strengths.

This dissertation describes the development and results of a physiological rigid body forward solution mathematical model that can be used to predict normal knee and total knee arthroplasty (TKA) kinematics and kinetics. The simulated activities include active extension and weight-bearing deep knee bend. The model includes both the patellofemoral and tibiofemoral joints. Geometry of the normal or implanted knee is represented by multivariate polynomials and modeled by constraining the velocity of lateral and medial tibiofemoral and patellofemoral contact points in a direction normal to the geometry surface. Center of mass, ligament and muscle attachment points and normal knee geometry were found using computer aided design (CAD) models built from computer tomography (CT) scans of a single subject. Quadriceps forces were the input for this model and were adjusted using a unique controller to control the rate of flexion, embedded with a controller which stabilizes the patellofemoral joint. The model was developed first using normal knee parameters. Once the normal knee model was validated, different total knee arthroplasty (TKA) designs were virtually implanted. The model was validated using in vivo data obtained through fluoroscopic analysis. In vivo data of the extension and deep knee bend activities from five non-implanted knees were used to validate the normal model kinematics. In vivo kinematic and kinetic data from a telemetric TKA with a tibia component instrumented with strain gauges was used to validate the kinematic and kinetic results of the model implanted with the TKA geometry. The tibiofemoral contact movement matched the trend seen in the in vivo data from the one patient available with this implant. The maximum axial tibiofemoral force calculated with the model was in 3.1% error with the maximum force seen in the in vivo data, and the trend of the contact forces matched well. Several other TKA designs were virtually implanted and analyzed to determine kinematics and bearing surface kinetics. The comparison between the model results and those previously assessed under in vivo conditions validates the effectiveness of the model and proves that it can be used to predict the in vivo kinematic and kinetic behavior of a TKA.

Conformational selection is the idea that proteins traverse positions on the conformational space represented by their potential energy landscape, and in particular positions considered as local energy minima. Conformational selection a useful concept in ligand binding studies and in exploring the behavior of protein structures within that energy landscape. Often, research that explores protein function requires the generation of conformational ensembles, or collections of protein conformations from a single structure. We describe a method of conformational ensemble generation that uses joint-constrained rigid-body dynamics (an approach that allows for explicit consideration of rigidity) and the elastic network model (providing structurally derived directional guides for the rigid-body model). We test our model on a selection of unbound proteins and examine the structural validity of the resulting ensembles, as well as the ability of such an approach to generate conformations with structural overlaps close to the ligand-bound versions of the proteins.

Modern space situational awareness entails the detection, tracking, identification, and characterization of resident space objects. Characterization is typically accomplished through the use of ground and space based sensors that are able to identify some specific physical feature, monitor unique dynamical behaviors, or deduce some information about the material properties of the object. The present investigation considers the characterizaiton aspects of situational awareness from the perspective of a close-proximity formation reconnaissance mission. The present study explores both relative translational and relative rotational motion for deployment of a spacecraft and observation of a resident space object. This investigation is motivated by specific situations in which characterization with ground or fixed space based sensors is insufficient. Instead, one or more vehicles are deployed in the vicinity of the object of interest. These could be, for instance, nano-satellites with imaging sensors. Nano-satellites offer a low-cost and effective technological platform, which makes consideration of the proposed scenario more feasible. Although the motivating application is rooted in space situational awareness, the techniques explored are generally applicable to flight in the vicinity of asteroids, and both cooperative vs. non-cooperative resident space objects. The investigation is initially focused on identifying the key features of the relative dynamics that are relevant to space situational awareness applications. Subsequently, effective spacecraft control techniques are considered to achieve the reconnaissance goals. / text

Conformational selection is the idea that proteins traverse positions on the conformational space represented by their potential energy landscape, and in particular positions considered as local energy minima. Conformational selection a useful concept in ligand binding studies and in exploring the behavior of protein structures within that energy landscape. Often, research that explores protein function requires the generation of conformational ensembles, or collections of protein conformations from a single structure. We describe a method of conformational ensemble generation that uses joint-constrained rigid-body dynamics (an approach that allows for explicit consideration of rigidity) and the elastic network model (providing structurally derived directional guides for the rigid-body model). We test our model on a selection of unbound proteins and examine the structural validity of the resulting ensembles, as well as the ability of such an approach to generate conformations with structural overlaps close to the ligand-bound versions of the proteins.

Engineering Dynamics (ED) courses are known as challenging and demanding for undergraduate students majored in many engineering fields, such as mechanical and aerospace engineering and civil and environmental engineering. The course is built upon the foundation and framework of mathematics and physics and requires students to have strong abstract thinking and reasoning skills. Rigid body dynamics (RBD), the second part of ED, investigates kinematics and kinetics of rigid bodies and is considered as a difficult subject by many undergraduate students because the course requires them to visualize abstract objects in motions. Although there have been many studies reporting the uses of interactive computer simulation and animation (CSA) modules as visual learning tools in RBD instruction, the effectiveness of the CSA modules on student learning of RBD were not rigorously and adequately investigated. This study employs a mixed method (QUAN – qual) approach and nonequivalent comparison group design to investigate the effectiveness of CSA modules on student learning of RBD, and to explore students’ attitudes towards and experiences with these modules. One hundred and sixty-one students in two recent semesters participated in this study: 74 in one semester participated in the comparison group and 87 in another semester participated in the intervention group. While the intervention group students studied RBD with CSA modules along with traditional lectures, the comparison group students studied RBD with traditional lectures only. Students in both groups were assessed with pretests and posttests using 10 bonus homework assignments developed to address core knowledge areas of RBD. The study uses a set of nonparametric statistical tools to analyze the pretest and posttest scores, mean differences, and magnitudes of the differences in learning gains between the two groups. Research findings from this study reveal that the intervention group students showed a significant increase in learning gains of overall knowledge, conceptual understanding, and procedural skills with Cliff’s effect sizes of 0.49, 0.41, and 0.47, respectively. CSA modules increased the intervention group students’ confidence, but they did not increase students’ motivation of learning RBD. This study supports the use of CSA modules as an instructional intervention to improve students’ conceptual understanding and procedural skills in learning engineering dynamics.

The wrist is one of the most complex joints in the human body. As such, the wrist joint is difficult to model due to the number of bones involved and its intricate soft tissue interactions. Many studies have attempted modeling the wrist previously; however, the majority of these studies simplify the joint into two-dimensions or idealized mechanical joints to reduce the complexity of the simulation. While these approaches still yield valuable information, the omission of a third-dimension or geometry defined movements limits the models’ usefulness in predicting joint function under non-idealized conditions. Therefore, the goal of this study was to develop a computational model of the wrist joint complex using commercially available software, whereby joint motion and behavior is dictated by highly accurate three-dimensional articular contact, ligamentous constraints, muscle loads, and external perturbations only. As such, a computational model of the human wrist was created using computed tomography (CT) images of a cadaver right upper extremity. Commercially available medical imaging software and three-dimensional computer aided design (CAD) software were used to reconstruct the osteoarticular surfaces and accurately add soft tissue constraints, as well as calculate kinematic motion simulations. The model was able to reproduce physiologic motion including flexion/extension and radial/ulnar deviation. Validation of the model was achieved by comparing predicted results from the model to the results of a published cadaveric experiment that analyzed wrist function under effects of various surgical procedures. The model was used to replicate the exact testing conditions prescribed for the experiment, and the model was able to accurately reproduce the trends and, in many instances, the magnitudes of the range of motion measurements in the study. Furthermore, the model can now be used to predict the magnitudes for the joint contact forces within the wrist as well as the tension developed in ligaments in hopes locating potential areas of concern after these surgical procedures have been conducted, including further development of arthritis in the wrist and ligament breakdown.

The glenohumeral joint is the most dislocated joint in the body due to the lack of bony constraints and dependence on soft tissue, primarily muscles and ligaments, to stabilize the joint. The goal of this study was to develop a computational model of the glenohumeral joint whereby joint behavior was dictated by articular contact, ligamentous constraints, muscle loading, and external perturbations. Validation of this computational model was achieved by comparing predicted results from the model to the results of a cadaveric experiment in which the relative contribution of muscles and ligaments to anterior joint stability was examined. The results showed the subscapularis to be critical to stabilization in both neutral and external rotations, the biceps stabilized the joint in neutral but not external rotation, and the inferior glenohumeral ligament resisted anterior displacement only in external rotation. Knowledge gained from this model could assist in pre-operative planning or the design of orthopedic implants. Use of this model as a companion to cadaveric testing could save valuable time and resources.

Orientador: Auteliano Antunes dos Santos Junior / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica / Made available in DSpace on 2018-08-16T12:15:36Z (GMT). No. of bitstreams: 1 Baruffaldi_LeonardoBartalini_M.pdf: 4986344 bytes, checksum: 359223cc9295f5b392b883e2841d037a (MD5) Previous issue date: 2010 / Resumo: Por 150 anos, os truques de três peças têm sido a estrutura padrão para o suporte de eixos e suspensões de trens de carga em diversos países. Embora sua robustez e facilidade de manutenção tenham conservado, em linhas gerais, a disposição e projeto dos componentes, novos requerimentos de carga e velocidade dos trens vêm mudando a forma como os projetistas enxergam o truque. Especial atenção tem sido dada ao modelo matemático da cunha de atrito, a peça fundida que é responsável pelo amortecimento dos vagões. A cunha de atrito promove a dissipação da energia mecânica por meio de contato de atrito seco com outros componentes do vagão. Devido às altas forças normais desenvolvidas nas superfícies de contato com características não suaves e, em geral, não lineares de atrito, as equações que regem o movimento da suspensão tornam-se de resolução difícil e surgem fenômenos como o de adesão escorregamento e o comportamento caótico típico de osciladores auto excitados. O presente trabalho tem como objetivo propor o uso de algoritmos de solução de problemas de complementaridade linear para resolver as forças de contato entre os corpos, visando a aprofundar a discussão sobre os modelos adotados para a cunha de atrito. Os resultados obtidos mostram que é possível modelar as forças de contato desse sistema utilizando um problema de complementaridade linear e que essa abordagem é, sob certas condições, mais eficiente do que o método das penalidades, normalmente aplicado para a resolução de problemas de contato / Abstract: For about 150 years now, three-piece trucks have been the standard axis' and suspensions' subframe used in freight railroad cars. The toughness and low maintenance costs of this system worked to maintain its basic design almost unchanged, but new requirements for loads and speed for freight cars are changing the way designers see the three-piece truck. Among the many interesting components of the three-piece truck, the friction wedge is getting some attention. The friction wedge is the main damping element in three-piece trucks and acts to dissipate mechanical energy via highly stiff contacts with friction. Due to the non-smooth and non-linear nature of frictional efforts, the equations of motion of the three-piece trucks become very awkward to deal with. Interesting phenomena of stick-slip, bifurcations, and limit cycle, typical of friction oscillators appear to some extent under normal operation. This work's main objective is to propose a new approach based on complementarity problems, used to solve for contact forces, to further extend the discussion on wedge dampers models. Results show that it is possible to model the problem using the linear complementarity problem and that, in some situations, this can be even more computationally efficient than the usual approach to solve contact problems: the penalty method / Mestrado / Mecanica dos Sólidos e Projeto Mecanico / Mestre em Engenharia Mecânica