Thesis: S.M., Massachusetts Institute of Technology, Department of Aeronautics and Astronautics, 2017. / Cataloged from PDF version of thesis. / Includes bibliographical references (pages 166-170). / Current human motion measurement systems using inertial measurement units (IMUs) typically rely on precise alignment, static calibration poses, or dynamic calibration motions. Muller et al. recently proposed a method for online calibration of the human elbow anatomical joint axes via decomposition of angular velocity measurements. This thesis evaluated this calibration-free method in the context of two motion types. First, the method is evaluated with human-generated motions common to occupational rehabilitation, to investigate activities of daily living (ADLs) as online calibration motions. Second, the method is evaluated with parameterized sinusoidal motion, to investigate amplitudes and frequencies of motions that yield robust axis estimations. It was found for the axis of interest, high on-axis motion and low off-axis motion lead to precise axis estimation and high accuracy estimation of the pronation/supination elbow axis. Further, high off-axis motion and low on-axis motion yielded imprecise axis estimation and inaccurate estimation of both the flexion/extension and pronation/supination elbow axes. A comparative study of different filtering methodologies to the estimation of upper extremity human motion was also performed. Compared to a motion capture truth, the Extended Kalman Filter (EKF) and Unscented Kalman Filter (UKF) were found to perform similarly. An implemented particle filter (PF) was found to perform better than both the EKF and UKF, and on the order of accuracy of a manufacturers black-box algorithm. This work is the first to evaluate a particle filter in the estimation of human motion by inertial sensors. The particle filter was then subject to a sensitivity analysis of the error of its estimated 3D orientation to its underlying algorithm inputs, namely, the accelerometer and magnetometer uncertainties, and number of particles. Recommended operational levels for these parameters are reported. Future work will combine the Muller auto-calibration method, robust IMU orientation filters, and knowledge of appropriate online motions to develop an IMU bias correction method for long periods of measurement. / by Timothy M. McGrath. / S.M.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 1990. / Title as it appears in the M.I.T. Graduate List, June, 1990: An application of the A* search technique to trajectory optimization. / Includes bibliographical references (leaves 87-88). / by Craig K. Niiya. / M.S.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 1997. / Includes bibliographical references (p. 199-201). / by Christopher John McLain. / M.S.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2011. / Cataloged from PDF version of thesis. / Includes bibliographical references (p. 97-102). / In producing a stop consonant, a soft tissue articulator, such as the lower lip, the tongue tip, or the tongue body, is raised to make an airtight closure. Stevens [I] pp 32 9-3 30 hypothesized that the interaction of the air pressure with the yielding soft-tissue wall would lead to a plateau-shaped release trajectory, and the duration of the plateau is progressively longer for bilabial, alveolar, and velar (Fig. 1-1). This thesis analyzes the pressure-wall interaction when a stop closure is released. Three flow models are implemented to derive the release trajectory: quasi-steady incompressible, unsteady incompressible, and unsteady compressible flow. Results from the models confirm Stevens' hypothesis. In the unsteady flow models, this thesis contributes a new method - deformable control volume analysis - to the pressure-wall interaction for small openings. This method may also be applied to quantify the unsteady effect during the closing and opening of the vocal folds and during the initial transient phase of a stop consonant, when the cross-sectional area is small. Indirect means of measuring an unknown parameter in the pressure-wall interaction analysis is discussed with the aid of a closure model which derives the condition of retaining a complete closure against air pressure buildup. In comparison with real speech data, an acoustic measure is defined for determining the duration of the frication noise of voiceless alveolar and velar stop consonants in syllable initial positions. This newly defined measure is based on the time variation of the average FFT magnitude in the whole frequency range and the magnitude in a 50-Hz-wide frequency band containing the front cavity resonance for the signal in every 5 milliseconds (a moving 5-ms window). This measure is found applicable to 25 releases out of 32 releases from TIMIT database. The means of the collected durations are found closest to the estimated duration calculated with the unsteady compressible flow model. / by Lan Chen. / S.M.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2007. / Includes bibliographical references (p. 165-169). / This thesis describes the design and performance results for the P-NMR fault tolerant avionics system architecture being developed at Draper Laboratory. The two key principles of the architecture are robust software partitioning (P), as defined by the ARINC 653 open standard, and N-Modular Redundancy (NMR). The P-NMR architecture uses cross channel data exchange and voting to implement fault detection, isolation and recovery (FDIR). The FDIR function is implemented in software that executes on commercial-off-the-shelf (COTS) hardware components that are also based on open standards. The FDIR function and the user applications execute on the same processor. The robust partitioning is provided by a COTS real-time operating system that complies with the ARINC 653 standard. A Triple Modular Redundant (TMR) prototype was developed and various performance metrics were collected. Evaluation of the TMR prototype indicates that the ARINC 653 standard is compatible with an NMR and FDIR architecture. Application partitions can be considered software fault containment regions which enhance the overall integrity of the system. The P-NMR performance metrics were compared with a previous Draper Laboratory design called the Fault Tolerant Parallel Processor (FTPP). This design did not make use of robust partitioning and it used proprietary hardware for implementing certain FDIR functions. The comparison demonstrated that the P-NMR system prototype could perform at an acceptable level and that the development of the system should continue. This research was done in the context of developing cost effective avionics systems for space exploration vehicles such as those being developed for NASA's Constellation program. / by Brendan Anthony O'Connell. / S.M.

Thesis: Ph. D., Massachusetts Institute of Technology, Department of Aeronautics and Astronautics, 2016. / This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections. / Cataloged from student-submitted PDF version of thesis. / Includes bibliographical references (pages 140-161). / Air transportation is an integral part of the economy and the transportation infrastructure. However, aircraft activity at airports generates CO2 emissions that affect the climate and other pollutants that affect air quality and human health. The focus of this thesis is to enable the reduction of the air quality impacts of aircraft operations at airports by (1) advancing the understanding of the relationship between aircraft activity and its air quality impacts and (2) evaluating the air quality benefits of controlling aircraft operations. There are atmospheric conditions where decreasing fuel burn (which is directly proportional to CO2 emissions) results in increased population exposure to fine particulate matter (PM2.5) and ozone (O3). This thesis quantifies the duration and magnitude of the tradeoffs between CO2 emissions and population exposure. The research complements current studies that optimize aircraft operations at airports for CO2 emissions but have not quantified the air quality implications of doing so. This raises the possibility of reducing the air quality impacts of airports beyond focusing only on minimizing fuel burn. Next, this thesis characterizes the atmospheric conditions that give rise to tradeoffs between emissions and population exposure to ozone. The ozone exposure response to nitrogen oxide (NOx) and Volatile Organic Compound (VOC) emissions is quantified as a function of ambient NOx and VOC concentrations using ozone exposure isopleths. This is the first time that ozone exposure isopleths are created for all locations in the US, using emission sensitivities from the adjoint of an air quality model. Metrics are calculated based on the isopleths which can be used to determine whether NOx and VOC emission reductions will improve ozone exposure or be counter-productive and the optimal NOx/VOC reduction ratio. Finally, this thesis calculates, for the first time, the air quality and climate benefits of pushback control and de-rated takeoffs for simulated aircraft operations at the Detroit Metropolitan Wayne County Airport (DTW). Operations are also optimized for minimum air quality, environmental and fuel combustion-related costs. The results show that the gate holding strategy is effective in mitigating the environmental impacts of taxi operations at airports, reducing CO2 emissions and air quality impacts by 35-40% relative to a baseline without gate holds. De-rated takeoffs at 75% thrust are effective in reducing the air quality impacts of takeoff operations by 19% but increase fuel burn by 3% relative to full-thrust takeoffs. Environmental costs are minimized with average optimal thrust setting of 81%, while maintenance cost savings are estimated to be 2 orders of magnitude larger than the increase in fuel costs from de-rated takeoffs. / by Akshay Ashok. / Ph. D.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2008. / Includes bibliographical references (p. 81-84). / Small aircraft engines traditionally have poorer performance compared to larger engines, which until recently, has been a factor that outweighed the aerodynamic benefits of commoditized and distributed propulsion. Improvements in the performance of small engines have, however, prompted another look at this old concept. This thesis examines aspects of aircraft engines that may have application to commodity thrust or distributed propulsion applications. Trends of engine performance with size and time are investigated. These trends are further extended to justify parameter choices for conceptual engines of the current, mid-term (10 years) and far-term (20 years). Uninstalled and installed performances are evaluated for these engines, and parametric studies are performed to determine the most influential and limiting factors. It is found that scaling down of engines is detrimental to SFC and fuel burn, mainly due to the Reynolds number effect. The more scaling done, the more prominent the effect. It is determined that new technology such as higher TIT, OPR and turbomachinery [eta]poly's for small aircraft engines enable the operation of larger bypass ratios, which is the most influential parameter to SFC and fuel bum. The increase of bypass ratio up to a value of 8 is found to be effective for such improvement. SFC decrease from the current to mid-term model is found to be ~20% and ~9% from mid-term to far-term. Range and endurance improvements are found to be ~30% and ~10% respectively for the mission examined. Finally, the mid-term engine model has performance comparable to that of a current, larger state-of-the-art engine, thus suggesting that improvement in small gas turbine technology in the next 10 years will make the application of commodity thrust or distributed propulsion an attractive option for future aircraft. / by Nicholas Y.S. Chan. / S.M.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2007. / Includes bibliographical references (p. 201). / The last decade has been a period of fundamental transformations for the US airline industry and has caused many carriers to make significant changes in their operational strategies. The traditional US network or "Legacy" carriers have had to deal with many new challenges including the devastating effects of 9/11, increased competition from low-cost airlines and increased volatility in fuel prices, to name a few. These setbacks have pushed many carriers into a financial crisis. In fact, four out of the six major airlines in the United States filed for bankruptcy protection between 2001 and 2005. In the midst of this crisis, these traditional carriers have had to concentrate on reducing their unit costs and improving their productivity levels in order to survive. The goal of the thesis is to examine to what extent these changes have led to a convergence in terms of unit costs and productivity levels between the Legacy carriers and their low-cost counterparts. Specifically we analyze and break down unit costs and productivity measures into their underlying components in order to identify what is driving change in the industry. We compare the different results at various levels of detail, including aggregate industry group trends, individual airline results and fleet-level based results comparing wide-body to narrow-body aircraft. We find that there are both qualitative and quantitative signs of convergence in several different categories in which LCCs have traditionally held a competitive advantage. These include unit costs excluding fuel and transport-related expenses, labor unit costs and employee wage productivity. On the Legacy side, the key forces driving improved efficiency have been dramatic labors cuts and higher stage lengths. / (cont.) The former has been achieved by utilizing the bankruptcy while the latter results from the shifting of capacity towards international markets. On the LCC side we find that a significant increase in labor wages resulting from increased staff seniority has been the main source of losses in certain productivity results. Despite these signs of convergence, our fleet-level based analysis also showed that LCCs still retain a significant competitive advantage when isolating narrow-body fleets which are usually flown in the domestic US markets. / by Gerassimos Tsoukalas. / S.M.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 1991. / Includes bibliographical references (leaves 66-67). / by Sen-Hao Lai. / M.S.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2002. / Includes bibliographical references (leaves 66-68). / by Mark Alexander Kepets. / S.M.