Reconstruction of Attenuated Hybrid Rocket Motor Chamber Pressure Signals Using Maximum Likelihood Estimation and Optimal Deconvolution

Chamber pressure, as it develops during rocket combustion, strongly correlates with many of the internal motor ballistics, including combustion stability, fuel regression rate, and mass flow. Chamber pressure is also an essential measurement for calculating achieved thrust coefficient and characteristic velocity. Due to the combustion environment hostility, sensing chamber pressure with high-fidelity presents a difficult measurement problem, especially for solid and hybrid rocket systems where combustion by-products contain high amounts of carbon and other sooty materials. These contaminants tend to deposit within the pneumatic tubing used to transmit pressure oscillations from the thrust chamber to the sensing transducer. Partially clogged transmission tubes exhibit significant response latency and damp high frequency pressure oscillations that may be of interest to the testers. A maximum-likelihood method for fitting a second order model to chamber pressure response is presented. The resulting model was used to reconstruct a high-fidelity motor response via optimal deconvolution. The method was applied to small hybrid-thruster results from three separate testing campaigns. Key performance parameters such as thrust coefficient, characteristic velocity, and specific impulse were re-calculated using the reconstructed data. Results were compared to the unreconstructed data, and are shown to exhibit consistently better agreement with theoretical predictions

Molecular gas dynamics applied to low-thrust propulsion

The Direct Simulation Monte Carlo method is currently being applied to study flowfields of small thrusters, including both the internal nozzle and the external plume flow. The DSMC method is employed because of its inherent ability to capture nonequilibrium effects and proper boundary physics in low-density flow that are not readily obtained by continuum methods. Accurate prediction of both the internal and external nozzle flow is important in determining plume expansion which, in turn, bears directly on impingement and contamination effects

Serine Hydrolases in M. smegmatis

This poster introduces a method of designing and building atomically-accurate protein sculptures. The sculptures are in the style of artist Julian Voss-Andreae, who developed a technique of creating miter-cut backbone traces from protein databank (PDB) files. Featuring a user-friendly, web-based interface, our program downloads a structure from the PDB and creates an interactive model of the protein rendered as a miter-cut backbone structure. After the user adjusts properties to achieve the desired look, the program generates a list of cutting instructions necessary to create an atomically-accurate sculpture from a symmetrical piece of wood. For the undergraduate student involved in this project, the balance between the raw coding and creative design has helped enforce the idea that art and science are, contrary to popular belief, not polarizing fields. In this way, the experience in working on this project parallels one of the goals of the project overall: to explore the relationships between art and science. The protein sculptures this code allows you to build are fundamentally built from mutual inspiration from art and science. Through deploying this website, we hope to instill a sense of intrigue in these fields in artists and scientists alike

Description Language

Notes on Application of the SQL Ada Modul

ICSE97 batch->interactive (fin)

ABSTRACT Software often evolves from batch to interactive use. Because these two usage styles are so different, batch systems usually require substantial changes to support interactive use. Specific issues that arise during conversion include assumptions about duration of system execution, incremental and partial processing, scope of processing, unordered and repeated processing, and error handling. Addressing these issues affects the implementation in the areas of memory management, assumptions and invariants, computational organization, and error handling. We use as a working example our conversion of the batch processor for the UniCon architecture description tool into an interactive architecture development tool. To capture the lessons for practitioners undertaking this type of conversion, we summarize with a checklist of design and implementation considerations