Thesis. 1978. M.S.--Massachusetts Institute of Technology. Dept. of Meteorology. / Microfiche copy available in Archives and Science. / Bibliography: leaves 159-160. / M.S.

Indiana University-Purdue University Indianapolis (IUPUI) / Monocular simultaneous localization and mapping (SLAM) is an important technique that enables very inexpensive environment mapping and pose estimation in small systems such as smart phones and unmanned aerial vehicles. However, the information generated by monocular SLAM is in an arbitrary and unobservable scale, leading to drift and making it difficult to use with other sources of odometry for control or navigation. To correct this, the odometry needs to be aligned with metric scale odometry from another device, or else scale must be recovered from known features in the environment. Typically known environmental features are not available, and for systems such as cellphones or unmanned aerial vehicles (UAV), which may experience sustained, small scale, irregular motion, an IMU is often the only practical option. Because accelerometers measure acceleration and gravity, an inertial measurement unit (IMU) must filter out gravity and track orientation with complex algorithms in order to provide a linear acceleration measurement that can be used to recover SLAM scale. In this thesis, an alternative method will be proposed, which detects and removes gravity from the accelerometer measurement by using the unscaled direction of acceleration derived from the SLAM odometry.

In a series of body objects, this project aims to discover the specific emotion of hopelessness through the physical sensation of gravity. The project is investigating a femininity concept by exploring the emotions evoked when reading about the myth of Pandora and how she is used in academic reports such as Diseases of Women to argue upon discriminating arguments directed towards a female identity. The outcome of the workshops situate this project in a participatory driven field where somatic experiences make it possible to discuss sensitive topics such as hopelessness and gender equality. The outcome of the project is five sensorial body objects that suggest possibilities in designing wear to trigger emotions. It should be presented as a participatory installation in an exhibition.

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Tea is China's traditional export-earning agricultural product. For a long time, China's tea exports have occupied an extremely important position in the international market. With the further opening of the international agricultural product market and the increasingly fierce competition in the international tea market, China's tea exports are increasingly being affected by technical barriers.The purpose of this paper is to empirically analyze which factors are affecting Chinese green tea exports. In addition, there is a focus on the trade status of Chinese green tea in the EU market, Japan and the United States. To achieve this objective, this paper adopts a modern approach to gravity models, i.e. an approach which uses specifications based on micro-foundations. Specifically, The paper uses a specification which explicitly takes into account the nature of multilateral trade resistance (MTR). More specifically, estimators based on traditional panel methods (combined with the recommended structures of dummies) and Silva-Tenreyro's (2006) PPML estimator (also combined with dummies). The results show that the maximum residue limits(MRL) of pesticides in importing countries have significantly impacted the export of Chinese tea. The cultural effects such as the Language similarity have a positive...

Dovetail joints are commonly seen in a furniture frame construction because of their unique configuration and strength. The tensile strength of dovetail joints was experimentally and analytically investigated using fracture mechanics method in this study. Experimental results of the investigation of effects of geometry factors on the tensile strength of dovetail joints in southern yellow pine and red oak indicated that the tensile strength of red oak joints was about 2 times higher than the one of southern yellow pine joints. Statistical analysis results indicated that the tail angle and tenon length of dovetail joints had significant influences on their tensile strength, and the tenon width was not a significant factor on the joint tensile strength. The fracture behaviors of southern yellow pine and red oak materials were investigated in the radial-longitudinal crack propagation system using a compact tension test method. Effects of wood specific gravity on fracture toughness for two wood species were studied in terms of their three growth ring combinations; earlywood, earlywood and latewood interface, and latewood. Regression analysis results indicated that the fracture toughness of two evaluated wood species can be predicted based on their specific gravity values. Statistical analyses indicated that the latewood yielded the significantly higher fracture toughness value, followed by earlywood and latewood interface, then earlywood for both wood species. Proposed prediction equations for tensile strengths of dovetail joints based on fracture toughness values of wooden materials used for frame construction were validated experimentally.

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This doctoral dissertation has mainly concentrated on modeling studies of shorter period acoustic-gravity waves propagating in the upper atmosphere. Several cases have been investigated in the literature, which are focusing on the propagation characteristics of high-frequency gravity wave packets. The dissertation consists of five main divisions of which each has its own significance to be addressed, and these five chapters are also bridged in order with each other to present a theme about gravity wave ducting dynamics, energetics, and airglows. The first chapter is served as an introduction of the general topic about atmospheric acoustic-gravity waves. Some of the historical backgrounds are provided as an interesting refreshment and also as a motivation reasoning this scientific research for decades. A new 2-D, time-dependent, and nonlinear model is introduced in the second chapter (the AGE-TIP model, acronymically named atmospheric gravity waves for the Earth plus tides and planetary waves). The model is developed during this entire doctoral study and has carried out almost all research results in this dissertation. The third chapter is a model application for shorter period gravity waves ducted in a thermally stratified atmosphere. In spite of mean winds the thermal ducting occurs because ducted waves are fairly common occurrences in airglow observations. One-dimensional Fourier analysis is applied to identify the ducted wave modes that reside within multiple thermal ducts. Besides, the vertical energy flux and the wave kinetic energy density are derived as wave diagnostic variables to better understand the time-resolved vertical transport of wave energy in the presence of multiple thermal ductings. The fourth chapter is also a model application for shorter period gravity waves, but it instead addresses the propagation of high-frequency gravity waves in the presence of mean background wind shears. The wind structure acts as a significant directional filter to the wave spectra and hence causes noticeable azimuthal variations at higher altitudes. In addition to the spectral analysis applied previously the wave action has been used to interpret the energy coupling between the waves and the mean flow among some atmospheric regions, where the waves are suspected to extract energy from the mean flow at some altitudes and release it to other altitudes. The fifth chapter is a concrete and substantial step connecting theoretical studies and realistic observations through nonlinearly coupling wave dynamic model with airglow chemical reactions. Simulated O (1S) (557.7 nm) airglow images are provided so that they can be compared with observational airglow images. These simulated airglow brightness variations response accordingly with minor species density fluctuations, which are due to propagating and ducting nonlinear gravity waves within related airglow layers. The thermal and wind structures plus the seasonal and geographical variabilities could significantly influence the observed airglow images. By control modeling studies the simulations can be used to collate with concurrent observed data, so that the incoherencies among them could be very useful to discover unknown physical processes behind the observed wave scenes.

In trajectory optimization, a common objective is to minimize propellant mass via multiple gravity assist maneuvers (MGAs). Some computer programs have been developed to analyze MGA trajectories. One of these programs, Parallel Global Multiobjective Optimization (PaGMO), uses an interesting technique known as the Island Model Paradigm. This work provides the community with a MATLAB optimizer, STOpS, that utilizes this same Island Model Paradigm with five different optimization algorithms. STOpS allows optimization of a weighted combination of many parameters. This work contains a study on optimization algorithm performance and how each algorithm is affected by its available settings. STOpS successfully found optimal trajectories for the Mariner 10 mission and the Voyager 2 mission that were similar to the actual missions flown. STOpS did not necessarily find better trajectories than those actually flown, but instead demonstrated the capability to quickly and successfully analyze/plan trajectories. The analysis for each of these missions took 2-3 days each. The final program is a robust tool that has taken existing techniques and applied them to the specific problem of trajectory optimization, so it can repeatedly and reliably solve these types of problems.