Search

In English, there are three -s related morphemes that are represented by the same “s” grapheme but acquired at different rates in child grammatical development: plural -s, possessive -s, and third person singular present tense -s (3s). There were two goals of this investigation. The first was to explore acoustic conditions of 3s in adult speech to further explain its challenging acquisition compared to non-morphemic, plural -s, and possessive -s. The second goal was clinically driven and sought to recommend salient acoustic environments for speech-language pathologists to consider in their selection of treatment targets. Participants were native English speaking adults recruited from Bowling Green State University’s campus (N = 9). Speech samples were collected of participants reading sentence stimuli that methodically controlled various contextual factors. Duration boundaries of 80 -s related morphemes per participant were labeled prior to analyses. Descriptive statistics were reported and linear mixed models were used to determine significant interactions between morpheme type, phoneme category, and sentence position for both duration and center of gravity measures. Results revealed 3s has a shorter duration than non-morphemic when in sentence-medial position and also experiences a lower CoG than non-morphemic when in sentence-final position. Lexical and grammatical factors are suspected to contribute more prominently than acoustics in explaining why 3s is difficult to acquire; however, these notable acoustic findings can be implemented by SLPs when creating treatment targets for grammar intervention.

The nuclear industry commonly uses uranium hexafluoride (UF6) in uranium conversion plants, uranium enrichment plants, and fuel fabrication plants. This chemical form of uranium is typically stored in 48Y and 30B cylinders while awaiting processing and in transit between facilities. The behavior of nuclear material inside 48Y and 30B cylinders while they are stored outside for long periods of time is an open question in the nuclear community. This is a difficult thing to measure because of the hazards associated with handling UF6, particularly its violent reaction with water. This work uses a force measurement to explore the behavior of UF6 inside a 30B cylinder over time. A platform scale system with four individually instrumented load cells was used to measure the force applied by the cylinder at each load cell. This information was then used to calculate the center of gravity in two dimensions. The validity of this approach was demonstrated in a laboratory setting, and corrections for sources of uncertainty (e.g., cylinder positioning and rotation) were developed to improve the ability to compare measured values. The experimental measurements collected by the platform scale system showed that UF6 does move over time inside a 30B cylinder sitting outside in a storage yard. The data also demonstrated that material movement appears to occur as a result of temperature, providing evidence that sublimation and desublimation occur in a cylinder while it is sitting outside.

Fingertip tactile sensing is an important perception for both human and robots. It can provide abundant information, such as contact detection, force feedback and even properties of objects including surface texture, geometry and so on. These information are essential in order for multi-fingered robot hands to perform dexterous grasping and manipulation tasks.This thesis introduces two new fingertip tactile sensors and relevant algorithms. One is based on a embedded camera capturing the fingertip’s deformation, which can measure simultaneously the contact position and normal, the 3-D contact force, and the local Radius of Curvature (RoC) of the object in contact with the fingertip. The experiment setup is introduced and approaches are verified. The other one is based on a six-axis Force/Torque (FT) sensor. Approaches based on force and torque information are proposed to detect the contact location and normal, occurrence of undesired motions, features of texture and the Center of Gravity (CoG) of the object. A general expression of error propagation of the CoG estimation is presented. After that, classification of different objects based on the CoG estimation and the foregoing tactile feedbacks are learned by a Neural Network (NN). The approaches are validated in simulation and experimentally.

This thesis uses empirical data to make the case that the architecture of Grammar is feed-�forward. There are three thematic parts: first, I discuss the separation of different phonetically important variables into modules and how a few prominent planning and production models have regarded the order of those modules. Then, I give a novel, statistical operationalization of the concept of feed-�forwardness. Finally, I present the results of a production experiment — targeting the center of gravity (COG) of American English [ʃ] — wherein multiple phonetically important variables are simultaneously manipulated. The aforementioned models are translated into linear mixed effects models and then compared based on their ability to predict the experimental data; I find that the model which corresponds to Keating & Shattuck�-Hufnagel’s 1989 model and Chomsky’s 1965 T�-model most parsimoniously fits the data, thereby providing phonetic evidence for a feed-�forward model of the Grammar. Discussion of some implications for phonetic and phonological research ensues.

NASA has initiated a series of tests aimed at understanding human physiological and biomechanical effects of spacesuits under a variety of conditions. Though these tests include metabolic rates, ground reaction forces, biomechanics, subjective workload and controllability feedback, the influences (kinematics, exertion and efficiency) of a combined spacesuit and portable life support system (PLSS) center of gravity (CG) during an astronaut’s extravehicular task performance has not been completely understood. The work described in this thesis was aimed at developing a quantitative means of evaluating the influence of space suit and PLSS CG location on astronaut EVA task performance in terms of kinematics (joint angular ranges), exertion (joint torques and muscle forces), and efficiency (comparative work performed). Four CG locations, representing approximate CG extremes for the NASA MK III and Z1 space suits, were evaluated using a combined experimental and computational approach. Three common EVA tasks were studied: object translation, climbing and walking. It was found that the Low-Aft CG was the best for object translation, the High-Forward CG for walking and the Low-Forward CG for climbing.

In this work, a novel algorithm for estimating aircraft center-of-gravity location based solely on traditional aircraft measurements is investigated. The algorithm uses known physics-based kinematic relationships between aircraft states for the estimation process and requires only traditional sensor measurements typically employed by aircraft. Three models are used in the algorithm development: one based on using attitude measurements, the second based on using air data measurements, and the third based on using navigation type measurements. Estimation of the aircraft's aerodynamic parameters is not required in the new approach. However, sensor error such as accelerometer bias effects are estimated in the algorithm process. A high performance aircraft simulation model is used to test the feasibility of the approach. In all individual and combined model simulations center-of-gravity was estimated with a high degree of accuracy. In addition, flight test data is used to verify the effectiveness of the algorithm in localizing the center-of-gravity successfully.

The main goal of this study is the use of polynomial chaos expansion (PCE) to analyze the uncertainty in calculating the lateral and longitudinal center of gravity for a vehicle from static load cell measurements. A secondary goal is to use experimental testing as a source of uncertainty and as a method to confirm the results from the PCE simulation. While PCE has often been used as an alternative to Monte Carlo, PCE models have rarely been based on experimental data. The 8-post test rig at the Virginia Institute for Performance Engineering and Research facility at Virginia International Raceway is the experimental test bed used to implement the PCE model. Experimental tests are conducted to define the true distribution for the load measurement systems' uncertainty. A method that does not require a new uncertainty distribution experiment for multiple tests with different goals is presented. Moved mass tests confirm the uncertainty analysis using portable scales that provide accurate results. The polynomial chaos model used to find the uncertainty in the center of gravity calculation is derived. Karhunen-Loeve expansions, similar to Fourier series, are used to define the uncertainties to allow for the polynomial chaos expansion. PCE models are typically computed via the collocation method or the Galerkin method. The Galerkin method is chosen as the PCE method in order to formulate a more accurate analytical result. The derivation systematically increases from one uncertain load cell to all four uncertain load cells noting the differences and increased complexity as the uncertainty dimensions increase. For each derivation the PCE model is shown and the solution to the simulation is given. Results are presented comparing the polynomial chaos simulation to the Monte Carlo simulation and to the accurate scales. It is shown that the PCE simulations closely match the Monte Carlo simulations.

The design of the landing gear is one of the more fundamental aspects of aircraft design. The design and integration process encompasses numerous engineering disciplines, e.g., structure, weights, runway design, and economics, and has become extremely sophisticated in the last few decades. Although the design process is well-documented, no attempt has been made until now in the development of a design methodology that can be used within an automated environment. As a result, the process remains to be a key responsibility for the configuration designer and is largely experience-based and graphically-oriented. However, as industry and government try to incorporate multidisciplinary design optimization (MDO) methods in the conceptual design phase, the need for a more systematic procedure has become apparent. The development of an MDO-capable design methodology as described in this work is focused on providing conceptual designer with tools to help automate the disciplinary analyses, i.e., geometry, kinematics, flotation, and weight. Documented design procedures and analyses were examined to determine their applicability, and to ensure compliance with current practices and regulations. Using the latest information as obtained from industry during initial industry survey, the analyses were in terms modified and expanded to accommodate the design criteria associated with the advanced large subsonic transports. Algorithms were then developed based on the updated analysis procedures to be incorporated into existing MDO codes.