Thesis. 1975. M.S.--Massachusetts Institute of Technology. Dept. of Ocean Engineering. / Bibliography: leaves 234-235. / by John G. Lundblad. / M.S.

abstract: Humans moving in the environment must frequently change walking speed and direction to negotiate obstacles and maintain balance. Maneuverability and stability requirements account for a significant part of daily life. While constant-average-velocity (CAV) human locomotion in walking and running has been studied extensively unsteady locomotion has received far less attention. Although some studies have described the biomechanics and neurophysiology of maneuvers, the underlying mechanisms that humans employ to control unsteady running are still not clear. My dissertation research investigated some of the biomechanical and behavioral strategies used for stable unsteady locomotion. First, I studied the behavioral level control of human sagittal plane running. I tested whether humans could control running using strategies consistent with simple and independent control laws that have been successfully used to control monopod robots. I found that humans use strategies that are consistent with the distributed feedback control strategies used by bouncing robots. Humans changed leg force rather than stance duration to control center of mass (COM) height. Humans adjusted foot placement relative to a "neutral point" to change running speed increment between consecutive flight phases, i.e. a "pogo-stick" rather than a "unicycle" strategy was adopted to change running speed. Body pitch angle was correlated by hip moments if a proportional-derivative relationship with time lags corresponding to pre-programmed reaction (87 ± 19 ms) was assumed. To better understand the mechanisms of performing successful maneuvers, I studied the functions of joints in the lower extremities to control COM speed and height. I found that during stance, the hip functioned as a power generator to change speed. The ankle switched between roles as a damper and torsional spring to contributing both to speed and elevation changes. The knee facilitated both speed and elevation control by absorbing mechanical energy, although its contribution was less than hip or ankle. Finally, I studied human turning in the horizontal plane. I used a morphological perturbation (increased body rotational inertia) to elicit compensational strategies used to control sidestep cutting turns. Humans use changes to initial body angular speed and body pre-rotation to prevent changes in braking forces. / Dissertation/Thesis / Ph.D. Kinesiology 2012

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 1980. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Bibliography: leaves 289-293. / by Wei-Yuan Hwang. / Ph.D.

In this thesis, the effects of split canard on the aerodynamic characteristics of missiles at high angles of attack are numerically investigated. Moreover, an enhanced semi-empirical engineering-level method is developed for prediction of normal force and pitching moment of split canard mounted missiles. In order to analyze the effects of split canard, a generic test case model is created by mounting a split canard to a generic test case model, NASA Dual Control Missile (NDCM), which was previously modeled and analyzed for the validation of CFD modeling. After obtaining a generic missile model with split canard, the effects of split canard on the aerodynamic characteristics of this missile in case of no control, pitch control, yaw control, and roll control deflections are numerically investigated. It is seen that the split canard decreases the local angle of attack of existing canard, increases the normal force and the maneuverability of the missile, and reduces the induced rolling moment at high angles of attack. Five different aerodynamic design parameters are determined for split canard and the effects of each parameter on missile aerodynamics are numerically investigated. It is seen that the roll orientation, deflection angle, size of the split canards have strong effects on missile&rsquo / s aerodynamic performance whereas longitudinal position of the split canards only affects the pitching moment of the missile. Finally, an enhanced semi-empirical engineering-level method, CFD-CBU, is developed for split canard mounted missiles in order to predict the normal force and the pitching moment coefficients. The developed method is validated with NDCM test case model. After this validation, the method is applied to the split canard mounted generic missile in case of no control deflection and pitch control deflection. The results of this method are compared with CFD results and it is seen that the results are in good agreement with each other.

Thesis: M.S., Massachusetts Institute of Technology, Department of Ocean Engineering, 1979 / Bibliography: leaves 65-66. / Wooi Tong Tan. / M.S. / M.S. Massachusetts Institute of Technology, Department of Ocean Engineering

Numerical simulations of waterjet inlets have been conducted in order to understand inlet performance during ship turning maneuvers. During turning maneuvers waterjet systems may experience low efficiency, cavitation, vibration, and noise. This study found that during turns less energy arrived at the waterjet pump relative to operating straight ahead, and that the flow field at the entrance of the waterjet pump exhibited a region of both low pressure and low axial velocity. The primary reason for the change in pump inflow uniformity is due to a streamwise vortex. In oblique inflow the hull boundary layer separates when entering the inlet and wraps up forming the streamwise vortex. These changes in pump inflow during turning maneuvers will result in increased unsteady loading of the pump rotor and early onset of pump rotor cavitation. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2015. / FAU Electronic Theses and Dissertations Collection

This dissertation consists of three main parts. The first part is to discuss aileron reversal problem for a typical section with linear aerodynamic and structural analysis. The result gives some insight and ideas for this aeroelastic problem. Although the aileron in its post-reversal state will work the opposite of its design, this type of phenomenon as a design root should not be ruled out on these grounds alone, as current active flight-control systems can compensate for this. Moreover, one can get considerably more (negative) lift for positive flap angle in this unusual regime than positive lift for positive flap angle in the more conventional setting. This may have important implications for development of highly maneuverable aircraft. The second part is to involve the nonlinear aerodynamic and structural analyses into the aileron reversal problem. Two models, a uniform cantilevered lifting surface and a rolling aircraft with rectangular wings, are investigated here. Both models have trailing-edge control surfaces attached to the main wings. A configuration that reverses at a relatively low dynamic pressure and flies with the enhanced controls at a higher level of effectiveness is demonstrated. To evaluate how reliable for the data from XFOIL, the data for the wing-aileron system from advanced CFD codes and experiment are used to compare with that from XFOIL. To enhance rolling maneuverability for an aircraft, the third part is to search for the optimal configuration during the post-reversal regime from a design point of view. Aspect ratio, hinge location, airfoil dimension, inner structure of wing section, composite skin, aeroelastic tailoring, and airfoil selection are investigated for cantilevered wing and rolling aircraft models, respectively. Based on these parametric structural designs as well as the aerodynamic characteristics of different airfoils, recommendations are given to expand AAW flight program.

<p>  </p> <p>Falls mostly occur when people are walking. Investigations of control of gait stability have focused primarily on the single stance phase. My dissertation focused on the double support phase of gait because (1) responses to perturbations occur during the double support (2) the portion of the gait cycle spent in double support is increased with old age, and, more importantly, (3) since both feet can push off the ground simultaneously, there are more kinetic degrees of freedom (DoF) and therefore greater control authority over body motion during this phase. However, how these kinetic DoFs are coordinated during the double support phase is not fully understood. Thus, the goal of this dissertation was to identify the inter-leg coordination to stabilize whole-body motion and quantify how the inter-leg coordination is affected by intrinsic and extrinsic factors. Specifically, Study 1 focused on healthy aging (an intrinsic factor) and varying task demands (an extrinsic factor that changed while curb ascent versus curb descent). Study 2 investigated another extrinsic factor of future uncertain environmental demands (fixed versus uncertain foot targeting demand for the step after descending a curb). Using the uncontrolled manifold analysis, I identified ground reaction variable (GRV) synergies, i.e., synergistic covariations between the ground reaction forces and moments under the two feet that stabilize whole-body linear and angular motions. Furthermore, I found that GRV synergies were modulated by extrinsic factors: GRV synergies were sensitive to current fixed environmental demands (Study 1), whereas they were robust to future environmental demands on foot placement (Study 2). Lastly, I found that GRV synergies were not changed by the intrinsic factor of age, despite the physiological declines with aging (Study 1). The absence of an age effect on GRV synergies indicates that older adults have the preserved ability to exploit the control authority during the double support phase to maintain stability while negotiating a curb. The work extends the current body of literature on gait stability mechanisms and improves our understanding of changes in stability control as a function of different environmental demands.</p>

The purpose of the following report is to account for and summarize the authority and tasks that municipalities, authorities and contractors have in the implementation of temporary traffic diversions. In addition to this, the cooperation between all actors has also been investigated with the aim of finding out what types of routines and potential tools are used in connection with the work. The implementation of the report is based on a qualitative study, for which relevant people with different tasks have been interviewed or answered questionnaires. Furthermore, governing documents for relevant parties have been studied with the intention of describing the requirements that apply to work adjacent to or on the road. The results have subsequently been compiled in an account of the work parties' tasks, views and suggestions for improvement. In this it appears that the road maintenance authorities have an examinative responsibility and has the authority to approve the work carried out on its behalf. For and in particular all road works, of which the diversion is a part, traffic device plans must also be drawn up and describe solutions for traffic-related problems. These are the tasks of the executing contractor to draft with regard to the requirements of the road maintenance authority. It also appears that the majority of the interviewees consider the cooperation to be satisfactory, but state how interpretation of the governing documents can result in conflicts between the parties. In addition, significant differences for the systems used in the coordination can be noted for each municipality and authority.

Esta dissertação de mestrado tem como objetivo a validação do modelo numérico de manobras para navios utilizado pelo simulador chamado SMH - Simulador Marítimo Hidroviário, que foi desenvolvido no laboratório Tanque de Provas Numérico. Para tanto foram realizados ensaios experimentais de manobras com um modelo em escala reduzida da embarcação Alpha Crucis com o objetivo de criar dados de manobra que serviram como referência para validação do modelo numérico. Foram selecionados diversos tipos de manobras com o propósito de criar uma caracterização da manobrabilidade da embarcação em baixas velocidades e regime transitório, permitindo a medição de diversas características, que permitem quantificar as capacidades de manobra da embarcação. Através de experimentos numéricos foram, então, realizadas as mesmas manobras executadas pelo modelo físico em escala reduzida, de forma a reproduzir as mesmas condições iniciais e os mesmos comandos, procurando reproduzir as manobras para validação do modelo implementado no SMH. Os resultados obtidos apresentam a aderência das características de manobras do modelo implementado no SMH, através da comparação das características de manobra obtidas pelo modelo físico em escala reduzida e das obtidas pelo modelo numérico. A dissertação apresenta ainda um estudo de sensibilidade que mostra o efeito dos principais fatores utilizados no laboratório Tanque de Provas Numérico para a calibração dos modelos de embarcações, mostrando que para as manobras consideradas neste trabalho alguns dos efeitos possuem pouca influência nos resultados. Por fim o trabalho conclui que o modelo matemático utilizado pelo SMH representa a capacidade de manobra da embarcação de forma consistente para diversos tipos de manobra, e com um grau de aderência satisfatório. / This research aims to present a validation for the ship maneuvering simulator named SMH, anachronym in Portuguese for Maritime and Waterway Simulator, developed on Tanque de Provas Numérico laboratory. For this propose small scale tests were performed with a model of Alpha Crucis ship aiming to create maneuver data that was used as reference for the numerical model validation. Several types of maneuver where selected to create a characterization of the maneuverability of the ship at low speeds and transient regime, and the parameters that quantify the maneuverability were measured. Then were performed numerical experiments recreating the same maneuver executed with the experimental model, with the same initial conditions and propulsion/rudder controls, trying to reproduce the maneuvers to validate the model implemented on the SMH. The results showed that the maneuvering characteristics predicted by the SMH simulator are similar to measured values in the experiment. The dissertation also presents a sensitivity study that shows the effect of the main parameters used in the laboratory Tanque de Provas Numérico for the vessel model calibration, This study showed that for some maneuvers, the tuning parameters have less influence on the results. Finally, the work concludes that the mathematical model used by the SMH represents the ability of the vessel to maneuver consistently for several types of maneuvers, and with a satisfactory degree of accuracy.