Publications
2009 |
Stoll, Enrico; Kwon, Daniel The benefit of multimodal telepresence for in-space robotic assembly Journal Article Robotics and Applications, 2009. BibTeX | Tags: @article{stoll2009benefit, title = {The benefit of multimodal telepresence for in-space robotic assembly}, author = {Enrico Stoll and Daniel Kwon}, year = {2009}, date = {2009-01-01}, journal = {Robotics and Applications}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
Stoll, Enrico; Wilde, Markus; Pong, Christopher Using virtual reality for human-assisted in-space robotic assembly Inproceedings Proc. World Congress on Engineering and Computer Science, 2009. BibTeX | Tags: @inproceedings{stoll2009using, title = {Using virtual reality for human-assisted in-space robotic assembly}, author = {Enrico Stoll and Markus Wilde and Christopher Pong}, year = {2009}, date = {2009-01-01}, booktitle = {Proc. World Congress on Engineering and Computer Science}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } |
Andrade, C; Ramirez-Mendoza, Ricardo; Giacoman-Zarzar, M; Morales, R; Fejzic, A; Saenz-Otero, A; Miller, DW Robust control applied towards rendezvous and docking Inproceedings Control Conference (ECC), 2009 European, pp. 1854–1859, IEEE 2009. BibTeX | Tags: @inproceedings{andrade2009robust, title = {Robust control applied towards rendezvous and docking}, author = {C Andrade and Ricardo Ramirez-Mendoza and M Giacoman-Zarzar and R Morales and A Fejzic and A Saenz-Otero and DW Miller}, year = {2009}, date = {2009-01-01}, booktitle = {Control Conference (ECC), 2009 European}, pages = {1854--1859}, organization = {IEEE}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } |
Mohan, Swati Tools for Reconfigurable Control System Comparisons for Autonomous Assembly Applications Inproceedings International Astronautical Congress, Daejon, South Korea, IAC-09 C, pp. 12–16, 2009. BibTeX | Tags: @inproceedings{mohan2009tools, title = {Tools for Reconfigurable Control System Comparisons for Autonomous Assembly Applications}, author = {Swati Mohan}, year = {2009}, date = {2009-01-01}, booktitle = {International Astronautical Congress, Daejon, South Korea, IAC-09 C}, volume = {1}, pages = {12--16}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } |
Tweddle, Brent; Saenz-Otero, Alvar; Miller, David Design and development of a visual navigation testbed for spacecraft proximity operations Inproceedings AIAA SPACE 2009 Conference & Exposition, pp. 6547, 2009. BibTeX | Tags: @inproceedings{tweddle2009design, title = {Design and development of a visual navigation testbed for spacecraft proximity operations}, author = {Brent Tweddle and Alvar Saenz-Otero and David Miller}, year = {2009}, date = {2009-01-01}, booktitle = {AIAA SPACE 2009 Conference & Exposition}, pages = {6547}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } |
Mohan, Swati; Miller, David SPHERES Reconfigurable Framework and Control System Design for Autonomous Assembly Inproceedings AIAA Guidance, Navigation, and Control Conference, pp. 5978, 2009. BibTeX | Tags: @inproceedings{mohan2009spheres, title = {SPHERES Reconfigurable Framework and Control System Design for Autonomous Assembly}, author = {Swati Mohan and David Miller}, year = {2009}, date = {2009-01-01}, booktitle = {AIAA Guidance, Navigation, and Control Conference}, pages = {5978}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } |
Mohan, Swati; Saenz-Otero, Alvar; Nolet, Simon; Miller, David W; Sell, Steven SPHERES flight operations testing and execution Journal Article Acta Astronautica, 65 (7-8), pp. 1121–1132, 2009. BibTeX | Tags: @article{mohan2009spheresb, title = {SPHERES flight operations testing and execution}, author = {Swati Mohan and Alvar Saenz-Otero and Simon Nolet and David W Miller and Steven Sell}, year = {2009}, date = {2009-01-01}, journal = {Acta Astronautica}, volume = {65}, number = {7-8}, pages = {1121--1132}, publisher = {Elsevier}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
Saenz-Otero, Alvar; Katz, Jacob; Mandy, Christophe; Miller, D SPHERES Demonstrations of Satellite Formations aboard the ISS Inproceedings Proc. 32nd Annu. AAS Guidance Control Conf., pp. 1–15, 2009. BibTeX | Tags: @inproceedings{saenz2009spheres, title = {SPHERES Demonstrations of Satellite Formations aboard the ISS}, author = {Alvar Saenz-Otero and Jacob Katz and Christophe Mandy and D Miller}, year = {2009}, date = {2009-01-01}, booktitle = {Proc. 32nd Annu. AAS Guidance Control Conf.}, pages = {1--15}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } |
Bruccoleri, Alexander Robert The Design and Feasibility of a 10 mN Chemical Space Propulsion Thruster By PhD Thesis 2009. BibTeX | Tags: @phdthesis{bruccoleriDesignFeasibility102009, title = {The Design and Feasibility of a 10 mN Chemical Space Propulsion Thruster By}, author = {Alexander Robert Bruccoleri}, year = {2009}, date = {2009-01-01}, number = {June}, keywords = {}, pubstate = {published}, tppubtype = {phdthesis} } |
Mohan, Swati; Saenz-Otero, Alvar; Nolet, Simon; Miller, David W; Sell, Steven SPHERES flight operations testing and execution Journal Article Acta Astronautica, 65 (7-8), pp. 1121–1132, 2009. BibTeX | Tags: @article{mohan2009spheresc, title = {SPHERES flight operations testing and execution}, author = {Swati Mohan and Alvar Saenz-Otero and Simon Nolet and David W Miller and Steven Sell}, year = {2009}, date = {2009-01-01}, journal = {Acta Astronautica}, volume = {65}, number = {7-8}, pages = {1121--1132}, publisher = {Elsevier}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
Chepko, Ariane Technology Selection and Architecture Optimization of In-Situ Resource Utilization Systems PhD Thesis 2009. BibTeX | Tags: @phdthesis{Chepko2009, title = {Technology Selection and Architecture Optimization of In-Situ Resource Utilization Systems}, author = {Ariane Chepko}, year = {2009}, date = {2009-01-01}, keywords = {}, pubstate = {published}, tppubtype = {phdthesis} } |
Diaz-Aguiló, Marc Optimal Interferometric Maneuvers for Distributed Telescopes PhD Thesis 2009, ISBN: 9781615679089. @phdthesis{diaz-aguiloOptimalInterferometricManeuvers2009, title = {Optimal Interferometric Maneuvers for Distributed Telescopes}, author = {Marc {Diaz-Aguiló}}, isbn = {9781615679089}, year = {2009}, date = {2009-01-01}, volume = {2}, number = {September}, abstract = {The scientfic community has proposed several missions to expand our knowledge about the universe, its formation and search for distant Earth-like planets. Most of the present space-based observation missions have reached angular resolution limits, therefore the potential benefits concerning angular resolution and intensity that can be reaped from the realization of interferometry within a distributed satellite telescope have led to the proposal of several multi-spacecraft systems. Among these missions synthetic imaging space based interferometers, consisting of multiple telescope apertures flying in controlled formation in order to combine received information from each of the flotilla members are nowadays the subject of interesting research. The objective of synthesizing images with high angular resolution, low ambiguity and high intensity is always a tradeoff with the whole fuel consumption of the mission. As a consequence, this research focuses on the design of interferometric maneuvers and optimal interferometric controllers balancing image performance and energy consumption. The first part of the work presents the optimization and design process of coordinated spiral maneuvers due to their interferometric interest when filling the frequency plane of the observed image. On the other hand, the second part focuses in the resolution of an optimal control problem within the LQ framework, to determine the optimal imaging reconfigurations of a formation flying system. Its objective is to balance the quality of the celestial observation and the fuel usage, which are the key aspects of any space-based observation mission. This study concerning implementability and performance of interferometric maneuvers will lead towards the enlargement of mission lifetime and flexibility of the system while conserving acceptable quality observations.}, keywords = {}, pubstate = {published}, tppubtype = {phdthesis} } The scientfic community has proposed several missions to expand our knowledge about the universe, its formation and search for distant Earth-like planets. Most of the present space-based observation missions have reached angular resolution limits, therefore the potential benefits concerning angular resolution and intensity that can be reaped from the realization of interferometry within a distributed satellite telescope have led to the proposal of several multi-spacecraft systems. Among these missions synthetic imaging space based interferometers, consisting of multiple telescope apertures flying in controlled formation in order to combine received information from each of the flotilla members are nowadays the subject of interesting research. The objective of synthesizing images with high angular resolution, low ambiguity and high intensity is always a tradeoff with the whole fuel consumption of the mission. As a consequence, this research focuses on the design of interferometric maneuvers and optimal interferometric controllers balancing image performance and energy consumption. The first part of the work presents the optimization and design process of coordinated spiral maneuvers due to their interferometric interest when filling the frequency plane of the observed image. On the other hand, the second part focuses in the resolution of an optimal control problem within the LQ framework, to determine the optimal imaging reconfigurations of a formation flying system. Its objective is to balance the quality of the celestial observation and the fuel usage, which are the key aspects of any space-based observation mission. This study concerning implementability and performance of interferometric maneuvers will lead towards the enlargement of mission lifetime and flexibility of the system while conserving acceptable quality observations. |
Gray, Thomas L Minimizing High Spatial Frequency Residual Error in Active Space Telescope Mirrors PhD Thesis 2009, ISSN: 0277786X. @phdthesis{grayMinimizingHighSpatial2009, title = {Minimizing High Spatial Frequency Residual Error in Active Space Telescope Mirrors}, author = {Thomas L Gray}, doi = {10.1117/12.824875}, issn = {0277786X}, year = {2009}, date = {2009-01-01}, volume = {7436}, number = {June}, keywords = {}, pubstate = {published}, tppubtype = {phdthesis} } |
Katz, Jacob Estimation and Control of Flexible Space Structures for Autonomous On-Orbit Assembly PhD Thesis 2009. @phdthesis{katzEstimationControlFlexible2009, title = {Estimation and Control of Flexible Space Structures for Autonomous On-Orbit Assembly}, author = {Jacob Katz}, year = {2009}, date = {2009-01-01}, number = {June}, keywords = {★}, pubstate = {published}, tppubtype = {phdthesis} } |
Tweddle, Brent; Saenz-Otero, Alvar; Miller, David Design and development of a visual navigation testbed for spacecraft proximity operations Inproceedings AIAA SPACE 2009 Conference & Exposition, pp. 6547, 2009. BibTeX | Tags: @inproceedings{tweddle2009designb, title = {Design and development of a visual navigation testbed for spacecraft proximity operations}, author = {Brent Tweddle and Alvar Saenz-Otero and David Miller}, year = {2009}, date = {2009-01-01}, booktitle = {AIAA SPACE 2009 Conference & Exposition}, pages = {6547}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } |
Kwon, Daniel W Cryogenic Heat Pipe for Cooling High Temperature Superconductors PhD Thesis 2009, ISSN: 00112275. Abstract | Links | BibTeX | Tags: F. Heat pipes, F. Space cryogenics, F. Superconducting magnets @phdthesis{kwonCryogenicHeatPipe2009, title = {Cryogenic Heat Pipe for Cooling High Temperature Superconductors}, author = {Daniel W Kwon}, doi = {10.1016/j.cryogenics.2009.07.005}, issn = {00112275}, year = {2009}, date = {2009-01-01}, volume = {49}, number = {9}, abstract = {The research in this paper investigates a consumable-free method of operating a high temperature superconducting (HTS) coil in space. The HTS wire resides inside a cryogenic heat pipe which is used for isothermalization. This paper presents the design, implementation, and testing of a cryogenic heat pipe for cooling high temperature superconductors. As a proof-of-concept, an 86 cm long straight heat pipe was constructed and enclosed two straight lengths of HTS wire. The working fluid, at saturation condition, maintains a constant temperature below the HTS wire critical temperature. Testing of the heat pipe in a vacuum chamber was conducted to verify the drop in HTS resistance correlating to the wire operating in a superconducting state. textcopyright 2009 Elsevier Ltd. All rights reserved.}, keywords = {F. Heat pipes, F. Space cryogenics, F. Superconducting magnets}, pubstate = {published}, tppubtype = {phdthesis} } The research in this paper investigates a consumable-free method of operating a high temperature superconducting (HTS) coil in space. The HTS wire resides inside a cryogenic heat pipe which is used for isothermalization. This paper presents the design, implementation, and testing of a cryogenic heat pipe for cooling high temperature superconductors. As a proof-of-concept, an 86 cm long straight heat pipe was constructed and enclosed two straight lengths of HTS wire. The working fluid, at saturation condition, maintains a constant temperature below the HTS wire critical temperature. Testing of the heat pipe in a vacuum chamber was conducted to verify the drop in HTS resistance correlating to the wire operating in a superconducting state. textcopyright 2009 Elsevier Ltd. All rights reserved. |
2008 |
Myers, Rebecca G Potential for Tsunami Detection and Early-Warning Using Space-Based Passive Microwave Radiometry PhD Thesis 2008, ISSN: 00653438. @phdthesis{myersPotentialTsunamiDetection2008, title = {Potential for Tsunami Detection and Early-Warning Using Space-Based Passive Microwave Radiometry}, author = {Rebecca G Myers}, issn = {00653438}, year = {2008}, date = {2008-01-01}, volume = {129 PART 3}, number = {February}, abstract = {The threat of a tsunami in coastal communities is considerable, especially in the Pacific and Indian Oceans. Current warning systems consist of two networks: (1) a network of seismometers, and (2) a network of sea level gauges and bottom pressure recorders. Bottom pressure recorders communicate with ocean surface buoys, which send the data to processing centers through satellite communication uplinks. The ability to quickly and accurately detect a tsunami in the deep ocean is proposed using space-based passive microwave radiometry. Passive microwave radiometry can detect oceanic parameters such as sea-surface temperature and sea surface roughness to contribute to earlier tsunami detection, when the tsunami is farther from shore, which will increase the reaction time for at-risk coastal communities.}, keywords = {}, pubstate = {published}, tppubtype = {phdthesis} } The threat of a tsunami in coastal communities is considerable, especially in the Pacific and Indian Oceans. Current warning systems consist of two networks: (1) a network of seismometers, and (2) a network of sea level gauges and bottom pressure recorders. Bottom pressure recorders communicate with ocean surface buoys, which send the data to processing centers through satellite communication uplinks. The ability to quickly and accurately detect a tsunami in the deep ocean is proposed using space-based passive microwave radiometry. Passive microwave radiometry can detect oceanic parameters such as sea-surface temperature and sea surface roughness to contribute to earlier tsunami detection, when the tsunami is farther from shore, which will increase the reaction time for at-risk coastal communities. |
Odegard, Ryan 2008, ISSN: 1098-6596. Abstract | Links | BibTeX | Tags: icle @phdthesis{odegardIncreasedConfidenceConcept2008, title = {Increased Confidence in Concept Design through Trade Space Exploration and Multiobjective Optimization}, author = {Ryan Odegard}, doi = {10.1017/CBO9781107415324.004}, issn = {1098-6596}, year = {2008}, date = {2008-01-01}, volume = {53}, number = {9}, abstract = {Predicting the binding mode of flexible polypeptides to proteins is an important task that falls outside the domain of applicability of most small molecule and protein-protein docking tools. Here, we test the small molecule flexible ligand docking program Glide on a set of 19 non-$alpha$-helical peptides and systematically improve pose prediction accuracy by enhancing Glide sampling for flexible polypeptides. In addition, scoring of the poses was improved by post-processing with physics-based implicit solvent MM- GBSA calculations. Using the best RMSD among the top 10 scoring poses as a metric, the success rate (RMSD $łeq$ 2.0 AA for the interface backbone atoms) increased from 21% with default Glide SP settings to 58% with the enhanced peptide sampling and scoring protocol in the case of redocking to the native protein structure. This approaches the accuracy of the recently developed Rosetta FlexPepDock method (63% success for these 19 peptides) while being over 100 times faster. Cross-docking was performed for a subset of cases where an unbound receptor structure was available, and in that case, 40% of peptides were docked successfully. We analyze the results and find that the optimized polypeptide protocol is most accurate for extended peptides of limited size and number of formal charges, defining a domain of applicability for this approach.}, keywords = {icle}, pubstate = {published}, tppubtype = {phdthesis} } Predicting the binding mode of flexible polypeptides to proteins is an important task that falls outside the domain of applicability of most small molecule and protein-protein docking tools. Here, we test the small molecule flexible ligand docking program Glide on a set of 19 non-$alpha$-helical peptides and systematically improve pose prediction accuracy by enhancing Glide sampling for flexible polypeptides. In addition, scoring of the poses was improved by post-processing with physics-based implicit solvent MM- GBSA calculations. Using the best RMSD among the top 10 scoring poses as a metric, the success rate (RMSD $łeq$ 2.0 AA for the interface backbone atoms) increased from 21% with default Glide SP settings to 58% with the enhanced peptide sampling and scoring protocol in the case of redocking to the native protein structure. This approaches the accuracy of the recently developed Rosetta FlexPepDock method (63% success for these 19 peptides) while being over 100 times faster. Cross-docking was performed for a subset of cases where an unbound receptor structure was available, and in that case, 40% of peptides were docked successfully. We analyze the results and find that the optimized polypeptide protocol is most accurate for extended peptides of limited size and number of formal charges, defining a domain of applicability for this approach. |
Panish, Robert Martin Vehicle Egomotion Estimation Using Computer Vision PhD Thesis 2008. @phdthesis{panishVehicleEgomotionEstimation2008, title = {Vehicle Egomotion Estimation Using Computer Vision}, author = {Robert Martin Panish}, year = {2008}, date = {2008-01-01}, volume = {19}, number = {22}, abstract = {A systematic review may encompass both odds ratios and mean differences in continuous outcomes. A separate meta-analysis of each type of outcome results in loss of information and may be misleading. It is shown that a ln(odds ratio) can be converted to effect size by dividing by 1.81. The validity of effect size, the estimate of interest divided by the residual standard deviation, depends on comparable variation across studies. If researchers routinely report residual standard deviation, any subsequent review can combine both odds ratios and effect sizes in a single meta-analysis when this is justified.}, keywords = {}, pubstate = {published}, tppubtype = {phdthesis} } A systematic review may encompass both odds ratios and mean differences in continuous outcomes. A separate meta-analysis of each type of outcome results in loss of information and may be misleading. It is shown that a ln(odds ratio) can be converted to effect size by dividing by 1.81. The validity of effect size, the estimate of interest divided by the residual standard deviation, depends on comparable variation across studies. If researchers routinely report residual standard deviation, any subsequent review can combine both odds ratios and effect sizes in a single meta-analysis when this is justified. |
Zayas, Daniel A Electromagnetic Extraction and Annihilation of Antiprotons for Spacecraft Propulsion PhD Thesis 2008. BibTeX | Tags: @phdthesis{2008, title = {Electromagnetic Extraction and Annihilation of Antiprotons for Spacecraft Propulsion}, author = {Daniel A Zayas}, year = {2008}, date = {2008-01-01}, keywords = {}, pubstate = {published}, tppubtype = {phdthesis} } |
Chung, Soon-Jo; Slotine, Jean-Jacques E; Miller, David W Propellant-free control of tethered formation flight, part 2: Nonlinear underactuated control Journal Article Journal of guidance, control, and dynamics, 31 (5), pp. 1437–1446, 2008. BibTeX | Tags: @article{chung2008propellant, title = {Propellant-free control of tethered formation flight, part 2: Nonlinear underactuated control}, author = {Soon-Jo Chung and Jean-Jacques E Slotine and David W Miller}, year = {2008}, date = {2008-01-01}, journal = {Journal of guidance, control, and dynamics}, volume = {31}, number = {5}, pages = {1437--1446}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
Fejzic, A; others, Results of SPHERES Microgravity Autonomous Docking Experiments in the Presence of Anomalies Inproceedings 59th International Astronautical Congress, 2008. BibTeX | Tags: @inproceedings{fejzic2008results, title = {Results of SPHERES Microgravity Autonomous Docking Experiments in the Presence of Anomalies}, author = {A Fejzic and others}, year = {2008}, date = {2008-01-01}, booktitle = {59th International Astronautical Congress}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } |
Saenz-Otero, Alvar; Aoude, G; Jeffrey, MM; Mohan, S; Fejzic, A; Katz, J; Edwards, CM; Miller, DW Distributed satellite systems algorithm maturation with SPHERES aboard the ISS Inproceedings International Astronautical Congress, Glasgow, Scotland, 2008. BibTeX | Tags: @inproceedings{saenz2008distributed, title = {Distributed satellite systems algorithm maturation with SPHERES aboard the ISS}, author = {Alvar Saenz-Otero and G Aoude and MM Jeffrey and S Mohan and A Fejzic and J Katz and CM Edwards and DW Miller}, year = {2008}, date = {2008-01-01}, booktitle = {International Astronautical Congress, Glasgow, Scotland}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } |
Mohan, Swati; Miller, David SPHERES reconfigurable control allocation for autonomous assembly Inproceedings AIAA guidance, navigation and control conference and exhibit, pp. 7468, 2008. BibTeX | Tags: @inproceedings{mohan2008spheres, title = {SPHERES reconfigurable control allocation for autonomous assembly}, author = {Swati Mohan and David Miller}, year = {2008}, date = {2008-01-01}, booktitle = {AIAA guidance, navigation and control conference and exhibit}, pages = {7468}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } |
Bogosian, Josef Roach Image Collection Optimization in the Design and Operation of Lightweight, Low Areal-Density Space Telescopes PhD Thesis 2008. BibTeX | Tags: @phdthesis{Bogosian2008, title = {Image Collection Optimization in the Design and Operation of Lightweight, Low Areal-Density Space Telescopes}, author = {Josef Roach Bogosian}, year = {2008}, date = {2008-01-01}, keywords = {}, pubstate = {published}, tppubtype = {phdthesis} } |
McCamish, Shawn; Romano, Marcello; Nolet, Simon; Edwards, Christine; Miller, David Ground and space testing of multiple spacecraft control during close-proximity operations Inproceedings AIAA Guidance, Navigation and Control Conference and Exhibit, pp. 6664, 2008. BibTeX | Tags: @inproceedings{mccamish2008ground, title = {Ground and space testing of multiple spacecraft control during close-proximity operations}, author = {Shawn McCamish and Marcello Romano and Simon Nolet and Christine Edwards and David Miller}, year = {2008}, date = {2008-01-01}, booktitle = {AIAA Guidance, Navigation and Control Conference and Exhibit}, pages = {6664}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } |
Gordon, Pierce August 6, 2008 MIT Summer Research program SPHERES Control of Attitude Control System using Reaction Wheels Journal Article 2008. BibTeX | Tags: @article{gordon2008august, title = {August 6, 2008 MIT Summer Research program SPHERES Control of Attitude Control System using Reaction Wheels}, author = {Pierce Gordon}, year = {2008}, date = {2008-01-01}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
Miller, David W; Mohan, Swati; Budinoff, Jason Assembly of a large modular optical telescope (ALMOST) Inproceedings Space Telescopes and Instrumentation 2008: Optical, Infrared, and Millimeter, pp. 70102H, International Society for Optics and Photonics 2008. BibTeX | Tags: @inproceedings{miller2008assembly, title = {Assembly of a large modular optical telescope (ALMOST)}, author = {David W Miller and Swati Mohan and Jason Budinoff}, year = {2008}, date = {2008-01-01}, booktitle = {Space Telescopes and Instrumentation 2008: Optical, Infrared, and Millimeter}, volume = {7010}, pages = {70102H}, organization = {International Society for Optics and Photonics}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } |
Chung, Soon-Jo; Miller, David W Propellant-free control of tethered formation flight, part 1: Linear control and experimentation Journal Article Journal of guidance, control, and dynamics, 31 (3), pp. 571–584, 2008. BibTeX | Tags: @article{chung2008propellantb, title = {Propellant-free control of tethered formation flight, part 1: Linear control and experimentation}, author = {Soon-Jo Chung and David W Miller}, year = {2008}, date = {2008-01-01}, journal = {Journal of guidance, control, and dynamics}, volume = {31}, number = {3}, pages = {571--584}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
Aoude, Georges S; How, Jonathan P; Miller, David W; others, Reconfiguration Maneuver Experiments Using the SPHERES Testbed Onboard the ISS Inproceedings 3rd International Symposium on Formation Flying, Missions and Technologies. Noordwijk, The Netherlands: ESA/ESTEC, 2008. BibTeX | Tags: @inproceedings{aoude2008reconfiguration, title = {Reconfiguration Maneuver Experiments Using the SPHERES Testbed Onboard the ISS}, author = {Georges S Aoude and Jonathan P How and David W Miller and others}, year = {2008}, date = {2008-01-01}, booktitle = {3rd International Symposium on Formation Flying, Missions and Technologies. Noordwijk, The Netherlands: ESA/ESTEC}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } |
Tweddle, Brent E; Saenz-Otero, Alvar SPHERES Development and Demonstrations of Close Proximity Formation Flight Maneuvers Inproceedings Proceedings of the 2008 National Technical Meeting of The Institute of Navigation, pp. 217–223, 2008. BibTeX | Tags: @inproceedings{tweddle2008spheres, title = {SPHERES Development and Demonstrations of Close Proximity Formation Flight Maneuvers}, author = {Brent E Tweddle and Alvar Saenz-Otero}, year = {2008}, date = {2008-01-01}, booktitle = {Proceedings of the 2008 National Technical Meeting of The Institute of Navigation}, pages = {217--223}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } |
Aoude, Georges S; How, Jonathan P; Garcia, Ian M Two-stage path planning approach for solving multiple spacecraft reconfiguration maneuvers Journal Article The Journal of the Astronautical Sciences, 56 (4), pp. 515–544, 2008. BibTeX | Tags: @article{aoude2008two, title = {Two-stage path planning approach for solving multiple spacecraft reconfiguration maneuvers}, author = {Georges S Aoude and Jonathan P How and Ian M Garcia}, year = {2008}, date = {2008-01-01}, journal = {The Journal of the Astronautical Sciences}, volume = {56}, number = {4}, pages = {515--544}, publisher = {Springer}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
Chung, SH Model-Based Planning through Constraint and Causal Order Decomposition PhD Thesis 2008. @phdthesis{Chung2008, title = {Model-Based Planning through Constraint and Causal Order Decomposition}, author = {SH Chung}, year = {2008}, date = {2008-01-01}, abstract = {One of the major challenges in autonomous planning and sequencing is the theoretical complexity of planning problems. Even a simple STRIPS planning problem is PSPACE- complete, and depending on the expressivity of the planning problem, the complexity of the problem can be EXPTIME-complete or worse. This thesis improves on current ap- proaches to sequencing the engineering operations of a spacecraft or ground-based asset through the explicit use of verifiable models and a decomposition approach to planning. Based on specifications of system behavior, the planner generates control sequences of engineering operations that achieve mission objectives specified by an operator. This work is novel in three ways. First, an innovative ``divide-and-conquer'' approach is used to assure efficiency and scalability of the planner. The key to the approach is in its combined use of constraint decomposition and causal order decomposition. This technique provides the means to decompose the problem into a set of subproblems and to identify the ordering by which each subproblem should be solved, thus reducing, and possibly eliminating, search. Second, the decomposed planning framework is able to solve complex planning problems with state constraints and temporally extended goals. Such complex system behavior is specified as concurrent, constraint automata (CCA) that provide the expressiveness necessary to model the behavior of the system components and their interactions. The mission objective is described as a desired evolution of goal states called a qualitative state plan (QSP), explicitly capturing the intent of the operators. Finally, the planner generates a partially-ordered plan called a qualitative control plan (QCP) that provides additional execution robustness through temporal flexibility. We demonstrate the decomposed approach to Model-based planning on a scenario based on the ongoing Autonomous Sciencecraft Experiment, onboard EO-1 spacecraft. The EO-1 problemhas a large state space with well over 660 quintillion states, 6.6texttimes 1020. Despite the size and the complexity of the problem, the time performance is linear in the length of the plan and the memory usage is linear in the number of components.}, keywords = {}, pubstate = {published}, tppubtype = {phdthesis} } One of the major challenges in autonomous planning and sequencing is the theoretical complexity of planning problems. Even a simple STRIPS planning problem is PSPACE- complete, and depending on the expressivity of the planning problem, the complexity of the problem can be EXPTIME-complete or worse. This thesis improves on current ap- proaches to sequencing the engineering operations of a spacecraft or ground-based asset through the explicit use of verifiable models and a decomposition approach to planning. Based on specifications of system behavior, the planner generates control sequences of engineering operations that achieve mission objectives specified by an operator. This work is novel in three ways. First, an innovative ``divide-and-conquer'' approach is used to assure efficiency and scalability of the planner. The key to the approach is in its combined use of constraint decomposition and causal order decomposition. This technique provides the means to decompose the problem into a set of subproblems and to identify the ordering by which each subproblem should be solved, thus reducing, and possibly eliminating, search. Second, the decomposed planning framework is able to solve complex planning problems with state constraints and temporally extended goals. Such complex system behavior is specified as concurrent, constraint automata (CCA) that provide the expressiveness necessary to model the behavior of the system components and their interactions. The mission objective is described as a desired evolution of goal states called a qualitative state plan (QSP), explicitly capturing the intent of the operators. Finally, the planner generates a partially-ordered plan called a qualitative control plan (QCP) that provides additional execution robustness through temporal flexibility. We demonstrate the decomposed approach to Model-based planning on a scenario based on the ongoing Autonomous Sciencecraft Experiment, onboard EO-1 spacecraft. The EO-1 problemhas a large state space with well over 660 quintillion states, 6.6texttimes 1020. Despite the size and the complexity of the problem, the time performance is linear in the length of the plan and the memory usage is linear in the number of components. |
Saenz-Otero, Alvar; Miller, David W Initial SPHERES Operations Aboard the International Space Station Incollection Small Satellites for Earth Observation, pp. 267–276, Springer, 2008. BibTeX | Tags: @incollection{saenz2008initial, title = {Initial SPHERES Operations Aboard the International Space Station}, author = {Alvar Saenz-Otero and David W Miller}, year = {2008}, date = {2008-01-01}, booktitle = {Small Satellites for Earth Observation}, pages = {267--276}, publisher = {Springer}, keywords = {}, pubstate = {published}, tppubtype = {incollection} } |
Courtney, Daniel George Development and Characterization of a Diverging Cusped Field Thruster and a Lanthanum Hexaboride Hollow Cathode PhD Thesis 2008. BibTeX | Tags: @phdthesis{courtneyDevelopmentCharacterizationDiverging2008, title = {Development and Characterization of a Diverging Cusped Field Thruster and a Lanthanum Hexaboride Hollow Cathode}, author = {Daniel George Courtney}, year = {2008}, date = {2008-01-01}, volume = {76}, number = {3}, keywords = {}, pubstate = {published}, tppubtype = {phdthesis} } |
Edwards, Christine M Proximity Operations of a Miniature Inspector Satellite Using Emulated Computer Vision PhD Thesis 2008. @phdthesis{Edwards2008, title = {Proximity Operations of a Miniature Inspector Satellite Using Emulated Computer Vision}, author = {Christine M Edwards}, year = {2008}, date = {2008-01-01}, keywords = {★}, pubstate = {published}, tppubtype = {phdthesis} } |
Howell, Deborah Spatial Nyquist Fidelity Method for Structural Models of Opto-Mechanical Systems PhD Thesis 2008, ISSN: 0277786X. Abstract | Links | BibTeX | Tags: @phdthesis{howellSpatialNyquistFidelity2008, title = {Spatial Nyquist Fidelity Method for Structural Models of Opto-Mechanical Systems}, author = {Deborah Howell}, doi = {10.1117/12.789111}, issn = {0277786X}, year = {2008}, date = {2008-01-01}, volume = {7017}, number = {August}, abstract = {Simulation models of new opto-mechanical systems are often based on engineering experience with older, potentially dissimilar systems. This can result in inaccuracies in the model prediction. A method is needed to gauge the fidelity of new system models in the initial design phases, often in the absence of hardware data. The Nyquist criterion is used to develop a quantitative measure of model fidelity, called the Nyquist fidelity metric. The spatial Nyquist fidelity method is presented which uses the Nyquist fidelity metric to both assess the fidelity of existing complex models and to synthesize new multi-component models starting from architectural considerations such as geometric and material properties of the system. This method also estimates the error bound on the output figures of merit based on the fidelity levels and sensitivity analysis. The Nyquist fidelity method is applied to the Modular Optical Space Telescope (MOST), the Thirty Meter Telescope, and the Stratospheric Observatory for Infrared Astronomy. It is shown in the MOST case study that the Nyquist fidelity method provides a 40% improvement in computational time while assuring less than 5% modal frequency error, and less than 2.2% error in the output figure of merit.}, keywords = {}, pubstate = {published}, tppubtype = {phdthesis} } Simulation models of new opto-mechanical systems are often based on engineering experience with older, potentially dissimilar systems. This can result in inaccuracies in the model prediction. A method is needed to gauge the fidelity of new system models in the initial design phases, often in the absence of hardware data. The Nyquist criterion is used to develop a quantitative measure of model fidelity, called the Nyquist fidelity metric. The spatial Nyquist fidelity method is presented which uses the Nyquist fidelity metric to both assess the fidelity of existing complex models and to synthesize new multi-component models starting from architectural considerations such as geometric and material properties of the system. This method also estimates the error bound on the output figures of merit based on the fidelity levels and sensitivity analysis. The Nyquist fidelity method is applied to the Modular Optical Space Telescope (MOST), the Thirty Meter Telescope, and the Stratospheric Observatory for Infrared Astronomy. It is shown in the MOST case study that the Nyquist fidelity method provides a 40% improvement in computational time while assuring less than 5% modal frequency error, and less than 2.2% error in the output figure of merit. |
Legge, Robert; Lozano, Paulo Performance of heavy ionic liquids with porous metal electrospray emitters Inproceedings 44th AIAA/ASME/SAE/ASEE Joint Propulsion Conference & Exhibit, pp. 5002, 2008. BibTeX | Tags: @inproceedings{legge2008performance, title = {Performance of heavy ionic liquids with porous metal electrospray emitters}, author = {Robert Legge and Paulo Lozano}, year = {2008}, date = {2008-01-01}, booktitle = {44th AIAA/ASME/SAE/ASEE Joint Propulsion Conference & Exhibit}, pages = {5002}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } |
Lee, Sang-il Design and Implementation of the State Estimator for Trajectory Following of an Electromagnetic Formation Flight Testbed PhD Thesis 2008. BibTeX | Tags: @phdthesis{leeDesignImplementationState2008, title = {Design and Implementation of the State Estimator for Trajectory Following of an Electromagnetic Formation Flight Testbed}, author = {Sang-il Lee}, year = {2008}, date = {2008-01-01}, number = {February}, keywords = {}, pubstate = {published}, tppubtype = {phdthesis} } |
Legge, Robert S Fabrication and Characterization of Porous Metal Emitters for Electrospray Applications PhD Thesis 2008. BibTeX | Tags: @phdthesis{leggeFabricationCharacterizationPorous2008, title = {Fabrication and Characterization of Porous Metal Emitters for Electrospray Applications}, author = {Robert S Legge}, year = {2008}, date = {2008-01-01}, number = {June}, keywords = {}, pubstate = {published}, tppubtype = {phdthesis} } |
2007 |
Lamamy, Julien-Alexandre Methods and Tools for the Formulation, Evaluation, and Optimization of Rover Mission Concepts PhD Thesis 2007. BibTeX | Tags: @phdthesis{Maschinena, title = {Methods and Tools for the Formulation, Evaluation, and Optimization of Rover Mission Concepts}, author = {Julien-Alexandre Lamamy}, year = {2007}, date = {2007-01-01}, keywords = {}, pubstate = {published}, tppubtype = {phdthesis} } |
McCloskey, Scott H Development of Legged, Wheeled, and Hybrid Rover Mobility Models to Facilitate Planetary Surface Exploration Mission Analysis PhD Thesis 2007. @phdthesis{mccloskeyDevelopmentLeggedWheeled2007, title = {Development of Legged, Wheeled, and Hybrid Rover Mobility Models to Facilitate Planetary Surface Exploration Mission Analysis}, author = {Scott H McCloskey}, year = {2007}, date = {2007-01-01}, number = {June}, abstract = {Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2007.}, keywords = {}, pubstate = {published}, tppubtype = {phdthesis} } Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2007. |
McGuire, T Improved Lifetimes and Synchronization Behavior in Multi-grid Inertial Electrostatic Confinement Fusion Devices PhD Thesis 2007. Abstract | BibTeX | Tags: Aeronautics and Astronautics @phdthesis{McGuire2007, title = {Improved Lifetimes and Synchronization Behavior in Multi-grid Inertial Electrostatic Confinement Fusion Devices}, author = {T McGuire}, year = {2007}, date = {2007-01-01}, abstract = {A high output power source is required for fast, manned exploration of the solar system, especially the outer planets. Travel times measured in months, not years, will require high power, lightweight nuclear systems. The mature nuclear concepts of solidcore fission and fusion Tokamaks do not satisfy the lightweight criteria due to massive radiators and magnets respectively. An attractive alternative is Inertial Electrostatic Confinement fusion. This extremely lightweight option has been studied extensively and to date has produced significant fusion rates of order 1010 reactions per second, but at low power gains, no higher than Q = 10-4. The major loss mechanisms for the state-of-the-art IEC are identified via a detailed reaction rate scaling analysis. The use of a single cathode grid causes short ion lifetimes and operation at high device pressure for simple ion generation both fundamentally limit the efficiency of these devices. Several improvements, including operation at much lower pressure with ion guns and the use of multiple cathode grids, are verified with particle-in-cell modeling to greatly improve the efficiency of IECs. These simulations show that the greatly increased confinement allows for the development of significant collective behavior in the recirculating ions. The plasma self-organizes from an initially uniform state into a synchronized, pulsing collection of ion bunches.(cont.) In simulations, these bunches are observed to be long-lived with lifetimes on the order of at least a tenth of a second, exceeding 20,000 passes. This represents a 3 order of magnitude improvement in confinement time and device efficiency. The synchronization of a bunch is due to the ion-ion interaction and kinematics of the well-confined IEC. The synchronization between beams is understood to arise from macroscale 'collisions' of bunches coupled with the kinematics of the device. Further, the collective effects limit the space charge buildup and higher densities result in violent ejection from the system. An IEC device which exploits the synchronization effect can achieve high efficiencies and gain, with fusion as the fastest collision timescale. Despite the potential of operation at break-even, the total power output is limited by the relatively low achievable core densities. The immediate application for this work is inexpensive neutron generators useful for medical, security, research, and industrial applications, but use much less power than a state-of-the-art IEC. The results of this thesis suggest two future research directions. First, neutralization of portions of the ion flow could allow greater densities and increase power output to levels required for space travel. Second, the idea of using kinematics coupled with ion-ion collisions to control thermalization may be applied to other plasma confinement concepts.}, keywords = {Aeronautics and Astronautics}, pubstate = {published}, tppubtype = {phdthesis} } A high output power source is required for fast, manned exploration of the solar system, especially the outer planets. Travel times measured in months, not years, will require high power, lightweight nuclear systems. The mature nuclear concepts of solidcore fission and fusion Tokamaks do not satisfy the lightweight criteria due to massive radiators and magnets respectively. An attractive alternative is Inertial Electrostatic Confinement fusion. This extremely lightweight option has been studied extensively and to date has produced significant fusion rates of order 1010 reactions per second, but at low power gains, no higher than Q = 10-4. The major loss mechanisms for the state-of-the-art IEC are identified via a detailed reaction rate scaling analysis. The use of a single cathode grid causes short ion lifetimes and operation at high device pressure for simple ion generation both fundamentally limit the efficiency of these devices. Several improvements, including operation at much lower pressure with ion guns and the use of multiple cathode grids, are verified with particle-in-cell modeling to greatly improve the efficiency of IECs. These simulations show that the greatly increased confinement allows for the development of significant collective behavior in the recirculating ions. The plasma self-organizes from an initially uniform state into a synchronized, pulsing collection of ion bunches.(cont.) In simulations, these bunches are observed to be long-lived with lifetimes on the order of at least a tenth of a second, exceeding 20,000 passes. This represents a 3 order of magnitude improvement in confinement time and device efficiency. The synchronization of a bunch is due to the ion-ion interaction and kinematics of the well-confined IEC. The synchronization between beams is understood to arise from macroscale 'collisions' of bunches coupled with the kinematics of the device. Further, the collective effects limit the space charge buildup and higher densities result in violent ejection from the system. An IEC device which exploits the synchronization effect can achieve high efficiencies and gain, with fusion as the fastest collision timescale. Despite the potential of operation at break-even, the total power output is limited by the relatively low achievable core densities. The immediate application for this work is inexpensive neutron generators useful for medical, security, research, and industrial applications, but use much less power than a state-of-the-art IEC. The results of this thesis suggest two future research directions. First, neutralization of portions of the ion flow could allow greater densities and increase power output to levels required for space travel. Second, the idea of using kinematics coupled with ion-ion collisions to control thermalization may be applied to other plasma confinement concepts. |
Mohan, Swati Reconfiguration Methods for On-orbit Servicing, Assembly, and Operations with Application to Space Telescopes PhD Thesis 2007. @phdthesis{Mohan2007a, title = {Reconfiguration Methods for On-orbit Servicing, Assembly, and Operations with Application to Space Telescopes}, author = {Swati Mohan}, year = {2007}, date = {2007-01-01}, abstract = {Reconfiguration is an important characteristic in furthering on-orbit servicing, assembly, and operations. Previous work has focused on large assemblers manipulating small payloads, where the dynamics of the assembler is not significantly changed. This work seeks to identify the impact of reconfiguration on maneuver performance. Reconfiguration is considered in two categories: implementation and application. Implementation of reconfiguration consisted of developing a method for defining and updating a configuration, implementation on the SPHERES testbed, and execution of tests (in simulation and on the International Space Station) to assess the control performance improvement after reconfiguration. Four applications were considered in this work, two hardware applications and two systems applications modeled through simulation. The objective of the SWARM application was to demonstrate autonomous assembly capability through docking and undocking maneuvers. The objective of the SIFFT application was to demonstrate formation reconfiguration capability, through the expansion and rotation of an equilateral triangle of three satellites. The objective of the systems applications was to determine the impact of reconfiguration in a larger mission context. One application, Mass Property Update, considered how the choice of method for obtaining the mass property information impacts operations. The other application, Modularity Analysis, considered how the implementation of modularity is driven by the mission objectives. Overall, this work has served to demonstrate the control impact of reconfiguration though implementation on the SPHERES testbed. This implementation was used on two hardware applications to determine the performance of reconfiguration for assembly and formation reconfiguration missions. Also, the impact of reconfiguration has been studied in the broader systems context. The choice of method of mass property update was demonstrated to have an impact on operations, in terms of reliability and mass. Finally, the method incorporation of modularity for purposes of on-orbit servicing and assembly was demonstrated to be driven by mission design parameters.}, keywords = {★}, pubstate = {published}, tppubtype = {phdthesis} } Reconfiguration is an important characteristic in furthering on-orbit servicing, assembly, and operations. Previous work has focused on large assemblers manipulating small payloads, where the dynamics of the assembler is not significantly changed. This work seeks to identify the impact of reconfiguration on maneuver performance. Reconfiguration is considered in two categories: implementation and application. Implementation of reconfiguration consisted of developing a method for defining and updating a configuration, implementation on the SPHERES testbed, and execution of tests (in simulation and on the International Space Station) to assess the control performance improvement after reconfiguration. Four applications were considered in this work, two hardware applications and two systems applications modeled through simulation. The objective of the SWARM application was to demonstrate autonomous assembly capability through docking and undocking maneuvers. The objective of the SIFFT application was to demonstrate formation reconfiguration capability, through the expansion and rotation of an equilateral triangle of three satellites. The objective of the systems applications was to determine the impact of reconfiguration in a larger mission context. One application, Mass Property Update, considered how the choice of method for obtaining the mass property information impacts operations. The other application, Modularity Analysis, considered how the implementation of modularity is driven by the mission objectives. Overall, this work has served to demonstrate the control impact of reconfiguration though implementation on the SPHERES testbed. This implementation was used on two hardware applications to determine the performance of reconfiguration for assembly and formation reconfiguration missions. Also, the impact of reconfiguration has been studied in the broader systems context. The choice of method of mass property update was demonstrated to have an impact on operations, in terms of reliability and mass. Finally, the method incorporation of modularity for purposes of on-orbit servicing and assembly was demonstrated to be driven by mission design parameters. |
Nilchiani, Roshanak Measuring the Value of Flexibility in Space Systems: A Six-Element Framework PhD Thesis 2007, ISSN: 10981241. Abstract | Links | BibTeX | Tags: Engineering systems, Real options analysis, Space systems, System flexibility, Uncertainty, Value of flexibility @phdthesis{nilchianiMeasuringValueFlexibility2007, title = {Measuring the Value of Flexibility in Space Systems: A Six-Element Framework}, author = {Roshanak Nilchiani}, doi = {10.1002/sys.20062}, issn = {10981241}, year = {2007}, date = {2007-01-01}, volume = {10}, number = {1}, abstract = {For many engineering systems, flexibility is an Important attribute that allows them to adapt to emerging changes. The existence of flexibility can help space systems adapt themselves to internal/external changes, or even take advantage of new possibilities while in space. Given the potential upfront cost of designing an engineering system to be more flexible, there is a need for a comprehensive framework that allows decision-makers to measure the value of flexible systems design in its different dimensions. Based on insights from the flexibility literature, this paper proposes a unified and comprehensive framework for measuring the value of flexibility in space systems based on six fundamental elements through which flexibility in engineering systems can be mapped. While the illustrative case study presented in this paper focuses on the value of flexibility In a space system, DARPA's Orbital Express program, this framework could generally be applicable for many other engineering systems. textcopyright 2006 Wiley Periodicals, Inc.}, keywords = {Engineering systems, Real options analysis, Space systems, System flexibility, Uncertainty, Value of flexibility}, pubstate = {published}, tppubtype = {phdthesis} } For many engineering systems, flexibility is an Important attribute that allows them to adapt to emerging changes. The existence of flexibility can help space systems adapt themselves to internal/external changes, or even take advantage of new possibilities while in space. Given the potential upfront cost of designing an engineering system to be more flexible, there is a need for a comprehensive framework that allows decision-makers to measure the value of flexible systems design in its different dimensions. Based on insights from the flexibility literature, this paper proposes a unified and comprehensive framework for measuring the value of flexibility in space systems based on six fundamental elements through which flexibility in engineering systems can be mapped. While the illustrative case study presented in this paper focuses on the value of flexibility In a space system, DARPA's Orbital Express program, this framework could generally be applicable for many other engineering systems. textcopyright 2006 Wiley Periodicals, Inc. |
Nolet, Simon Development of a Guidance, Navigation and Control Architecture and Validation Process Enabling Autonomous Docking to a Tumbling Satellite PhD Thesis 2007. @phdthesis{Nolet2007a, title = {Development of a Guidance, Navigation and Control Architecture and Validation Process Enabling Autonomous Docking to a Tumbling Satellite}, author = {Simon Nolet}, year = {2007}, date = {2007-01-01}, keywords = {★}, pubstate = {published}, tppubtype = {phdthesis} } |
Pucci, Justin Matthew An Analysis of Energy Balance in a Helicon Plasma Source for Space Propulsion PhD Thesis 2007. @phdthesis{Pucci2007a, title = {An Analysis of Energy Balance in a Helicon Plasma Source for Space Propulsion}, author = {Justin Matthew Pucci}, year = {2007}, date = {2007-01-01}, abstract = {This thesis covers work done on the mHTX@MIT helicon source as it relates to the analysis of power losses. A helicon plasma is a rather complex system with many potential loss mechanisms. Among the most dominant are optical radiation emission, wall losses due to poor magnetic confinement, and poor antenna-plasma coupling. This work sought to establish a first-order breakdown of the loss mechanisms in the mHTX@MIT helicon source so as to allow for a better understanding of the issues effecting efficiency. This thesis proposes the use of a novel thermocouple array, standard plasma diagnostics, and a simple global energy balance model of the system to determine greater details regarding the losses incurred during regular operation. From this it may be possible, by comparing the heat flux on the tube to the applied magnetic field profile, to gain some insight into the effects of magnetic field geometry on the character of the helicon discharge.}, keywords = {}, pubstate = {published}, tppubtype = {phdthesis} } This thesis covers work done on the mHTX@MIT helicon source as it relates to the analysis of power losses. A helicon plasma is a rather complex system with many potential loss mechanisms. Among the most dominant are optical radiation emission, wall losses due to poor magnetic confinement, and poor antenna-plasma coupling. This work sought to establish a first-order breakdown of the loss mechanisms in the mHTX@MIT helicon source so as to allow for a better understanding of the issues effecting efficiency. This thesis proposes the use of a novel thermocouple array, standard plasma diagnostics, and a simple global energy balance model of the system to determine greater details regarding the losses incurred during regular operation. From this it may be possible, by comparing the heat flux on the tube to the applied magnetic field profile, to gain some insight into the effects of magnetic field geometry on the character of the helicon discharge. |
Sakaguchi, Aya Micro-Electromagnetic Formation Flight of Satellite Systems PhD Thesis 2007, ISSN: 1098-6596. Abstract | Links | BibTeX | Tags: icle @phdthesis{sakaguchiMicroElectromagneticFormationFlight2007, title = {Micro-Electromagnetic Formation Flight of Satellite Systems}, author = {Aya Sakaguchi}, doi = {10.1017/CBO9781107415324.004}, issn = {1098-6596}, year = {2007}, date = {2007-01-01}, abstract = {Predicting the binding mode of flexible polypeptides to proteins is an important task that falls outside the domain of applicability of most small molecule and protein-protein docking tools. Here, we test the small molecule flexible ligand docking program Glide on a set of 19 non-$alpha$-helical peptides and systematically improve pose prediction accuracy by enhancing Glide sampling for flexible polypeptides. In addition, scoring of the poses was improved by post-processing with physics-based implicit solvent MM- GBSA calculations. Using the best RMSD among the top 10 scoring poses as a metric, the success rate (RMSD $łeq$ 2.0 AA for the interface backbone atoms) increased from 21% with default Glide SP settings to 58% with the enhanced peptide sampling and scoring protocol in the case of redocking to the native protein structure. This approaches the accuracy of the recently developed Rosetta FlexPepDock method (63% success for these 19 peptides) while being over 100 times faster. Cross-docking was performed for a subset of cases where an unbound receptor structure was available, and in that case, 40% of peptides were docked successfully. We analyze the results and find that the optimized polypeptide protocol is most accurate for extended peptides of limited size and number of formal charges, defining a domain of applicability for this approach.}, keywords = {icle}, pubstate = {published}, tppubtype = {phdthesis} } Predicting the binding mode of flexible polypeptides to proteins is an important task that falls outside the domain of applicability of most small molecule and protein-protein docking tools. Here, we test the small molecule flexible ligand docking program Glide on a set of 19 non-$alpha$-helical peptides and systematically improve pose prediction accuracy by enhancing Glide sampling for flexible polypeptides. In addition, scoring of the poses was improved by post-processing with physics-based implicit solvent MM- GBSA calculations. Using the best RMSD among the top 10 scoring poses as a metric, the success rate (RMSD $łeq$ 2.0 AA for the interface backbone atoms) increased from 21% with default Glide SP settings to 58% with the enhanced peptide sampling and scoring protocol in the case of redocking to the native protein structure. This approaches the accuracy of the recently developed Rosetta FlexPepDock method (63% success for these 19 peptides) while being over 100 times faster. Cross-docking was performed for a subset of cases where an unbound receptor structure was available, and in that case, 40% of peptides were docked successfully. We analyze the results and find that the optimized polypeptide protocol is most accurate for extended peptides of limited size and number of formal charges, defining a domain of applicability for this approach. |
Shannon, Y Cheng, and Martinez-sanchez, Manuel, "Modeling of Hall Thruster Lifetime and Erosion," . PhD Thesis 2007. BibTeX | Tags: @phdthesis{shannonChengMartinezsanchezManuel2007, title = {Cheng, and Martinez-sanchez, Manuel, "Modeling of Hall Thruster Lifetime and Erosion," .}, author = {Y Shannon}, year = {2007}, date = {2007-01-01}, number = {May}, keywords = {}, pubstate = {published}, tppubtype = {phdthesis} } |
Shull, Sarah A Modeling and Simulation of Lunar Campaign Logistics PhD Thesis 2007, ISBN: 1563479079. Abstract | Links | BibTeX | Tags: @phdthesis{shullModelingSimulationLunar2007, title = {Modeling and Simulation of Lunar Campaign Logistics}, author = {Sarah A Shull}, doi = {10.2514/6.2007-6244}, isbn = {1563479079}, year = {2007}, date = {2007-01-01}, volume = {3}, number = {May}, abstract = {As NASA prepares to establish a manned outpost on the lunar surface, it is essential to consider the logistics of both the construction and operation of this outpost. This paper presents the results of numerous trade studies performed using SpaceNet to analyze a notional lunar campaign architecture in terms of its robustness to campaign level risks such as flight delays, flight cancellations and uncertain demand parameters.}, keywords = {}, pubstate = {published}, tppubtype = {phdthesis} } As NASA prepares to establish a manned outpost on the lunar surface, it is essential to consider the logistics of both the construction and operation of this outpost. This paper presents the results of numerous trade studies performed using SpaceNet to analyze a notional lunar campaign architecture in terms of its robustness to campaign level risks such as flight delays, flight cancellations and uncertain demand parameters. |