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  <title><![CDATA[PhD Defense by Yuri Shimane]]></title>
  <body><![CDATA[<p>Yuri Shimane<br>(Advisor: Prof. Koki Ho)<br>will defend a doctoral thesis entitled,<br>Modeling, Optimization, and Validation of In-Space Facility Location Problem<br>on<br>Wednesday, May 21 at 9:00 a.m.<br>CODA C1015 Vinings<br>756 West Peachtree Street, Atlanta, GA 30332<br>Abstract<br>This thesis is centered on in-space facility location problems (FLPs). The FLP provides a general&nbsp;<br>framework to consider the placement and allocation of in-space assets, for applications ranging&nbsp;<br>from in-space servicing to cislunar space situational awareness. Compared to terrestrial problems,&nbsp;<br>in-space applications require considerations of the underlying &nbsp;orbital &nbsp;mechanics &nbsp;and &nbsp;the &nbsp;<br>associated &nbsp;nonlinear, &nbsp;potentially &nbsp;time-varying performance metrics. This thesis presents general&nbsp;<br>considerations to determine whether a static or a time-expanded in-space FLP formulation is&nbsp;<br>appropriate for the application at hand; then, example space-based problems for both static and&nbsp;<br>time-expanded cases are provided. With the time-expanded FLP, where the problem dimension becomes&nbsp;<br>particularly large due to the time dependency of performance metrics and, consequently, of the&nbsp;<br>allocation decisions, a customized Lagrangian relaxation algorithm together with a set of&nbsp;<br>specialized heuristics is proposed.<br>In the context of cislunar infrastructures, libration point orbits (LPOs) provide relatively stable&nbsp;<br>and geometrically diverse orbits for assets to be located. Motivated by the signiﬁcantly lower&nbsp;<br>number of existing missions in cislunar libration point orbits (LPOs), this thesis also provides&nbsp;<br>orbital validation of LPOs in a high-ﬁdelity ephemeris model (HFEM). The validation consists of two&nbsp;<br>steps: ﬁrst, the nominal ballistic and quasi-ballistic design problem is considered through an&nbsp;<br>optimal control approach. Then, station-keeping along the designed baseline in the presence of&nbsp;<br>uncertainties and operational constraints is studied. A targeting model predictive control scheme,&nbsp;<br>suitable for both ballistic and quasi-ballistic baselines, is devised and demonstrated to provide&nbsp;<br>satisfactory station-keeping performance, both in terms of cumulative cost and tracking deviation,&nbsp;<br>over extended durations.<br>Committee<br>• &nbsp;Prof. Koki Ho – School of Aerospace Engineering (advisor)<br>• &nbsp;Prof. Glenn Lightsey – School of Aerospace Engineering<br>• &nbsp;Prof. John Christian – School of Aerospace Engineering<br>• &nbsp;Dr. Dario Izzo – European Space Agency<br>• &nbsp;Dr. Gregory Badura – Georgia Tech Research Institute<br>&nbsp;</p>]]></body>
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