Construction and performance of an inverted pendulum thrust balance

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2010.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 (p. 133-134).The objective of the work in this thesis was to devise a means of profiling the thrust of the MIT Space Propulsion Lab's (SPL) Diverging Cusped Field (DCF) thruster and, more generally, other thrusters of similar size and thrust levels. The former SPL thrust stand, which had been used to characterize the BHT-200 engine, was not suitable for the DCF because of its torsional style design. An entirely new, inverted pendulum-type balance needed to be built. The new design employs a vertical arm with the DCF situated at the top and a counterweight placed at the bottom. The vertical arm rotates at the fulcrum through a flexible pivot attached to a base. A horizontal thrust force from the DCF causes the balance to rotate. This motion is sensed by a linear variable differential transformer (LVDT) and counteracted by a force from a voice coil. The voice coil's neutralizing force nulls the balance back to an equilibrium position and supplies the thrust value produced by the DCF. The inverted pendulum thrust balance was built from an initial design proposed by Professor Manuel Martinez-Sanchez. Many of the electrical components found on the old thrust stand, like the LVDT and the voice coil, were incorporated into the new one. Additionally, the control software and hardware from the old stand required several changes and updates to be compatible with the new design. After the assembly of the new thrust balance, the issues of calibration and thermal drift during use were also addressed. Once a means of correcting the undesired operational forces and thermal effects had been established, the balance displayed thrust measurement within a range of 0mN to 23mN with an uncertainties as low as ±0.5mN.by Brett R. Tartler.S.M

Tracking Load-time Configuration Options

Highly-configurable software systems are pervasive, although configuration options and their interactions raise complexity of the program and increase maintenance effort. Especially load-time configuration options, such as parameters from command-line options or configuration files, are used with standard programming constructs such as variables and if statements intermixed with the program’s implementation; manually tracking configuration options from the time they are loaded to the point where they may influence controlflow decisions is tedious and error prone. We design and implement Lotrack, an extended static taint analysis to automatically track configuration options. Lotrack derives a configuration map that explains for each code fragment under which configurations it may be executed. An evaluation on Android applications shows that Lotrack yields high accuracy with reasonable performance. We use Lotrack to empirically characterize how much of the implementation of Android apps depends on the platform’s configuration options or interactions of these options

Halbtechnische Untersuchungen zur Guellebehandlung durch Nassoxidation Abschlussbericht

Available from TIB Hannover: FR 6490+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Towards Adjusting Mobile Devices to User’s Behaviour

Abstract. Mobile devices are a special class of resource-constrained em-bedded devices. Computing power, memory, the available energy, and network bandwidth are often severely limited. These constrained re-sources require extensive optimization of a mobile system compared to larger systems. Any needless operation has to be avoided. Time-consuming operations have to be started early on. For instance, load-ing files ideally starts before the user wants to access the file. So-called prefetching strategies optimize system’s operation. Our goal is to ad-just such strategies on the basis of logged system data. Optimization is then achieved by predicting an application’s behavior based on facts learned from earlier runs on the same system. In this paper, we ana-lyze system-calls on operating system level and compare two paradigms, namely server-based and device-based learning. The results could be used to optimize the runtime behaviour of mobile devices