3,885 research outputs found
Large-angle slewing maneuvers for flexible spacecraft
A new class of closed-form solutions for finite-time linear-quadratic optimal control problems is presented. The solutions involve Potter's solution for the differential matrix Riccati equation, which assumes the form of a steady-state plus transient term. Illustrative examples are presented which show that the new solutions are more computationally efficient than alternative solutions based on the state transition matrix. As an application of the closed-form solutions, the neighboring extremal path problem is presented for a spacecraft retargeting maneuver where a perturbed plant with off-nominal boundary conditions now follows a neighboring optimal trajectory. The perturbation feedback approach is further applied to three-dimensional slewing maneuvers of large flexible spacecraft. For this problem, the nominal solution is the optimal three-dimensional rigid body slew. The perturbation feedback then limits the deviations from this nominal solution due to the flexible body effects. The use of frequency shaping in both the nominal and perturbation feedback formulations reduces the excitation of high-frequency unmodeled modes. A modified Kalman filter is presented for estimating the plant states
Sports foods and dietary supplements for optimal function and performance enhancement in track and field athletes
Numerous nutritional products are marketed with claims of optimizing athlete health and function and/or enhancing performance. Products that fall under the banner of “Sports Foods” or “Dietary Supplements,” may be used to support performance during training and competition or for enhancing aspects of training adaptation, recovery, immune function, and/or overall athlete health. Effective marketing campaigns and athlete endorsements may convince us that certain sports foods and supplements are fundamental in allowing athletes to reach their sporting goals. However, this approach is naive in understanding the true foundations of athlete success, such as the inherent genetic predisposition for athletic characteristics, the many hours of well-structured/periodized training, appropriate underlying nutrition, adequate sleep and recovery, and of course, good overall physical and mental health. Nevertheless, if these variables are all accounted for, there may be a role for sports foods and dietary supplements in an athlete’s training and competition routine, particularly within elite sport where marginal performance gains are pursued. The following review presents general considerations for track-and-field athletes using sports foods and dietary supplements to enhance performance, in addition to exploring the potential therapeutic/prophylactic use of these nutritional aids
Transform methods for precision continuum and control models of flexible space structures
An open loop optimal control algorithm is developed for general flexible structures, based on Laplace transform methods. A distributed parameter model of the structure is first presented, followed by a derivation of the optimal control algorithm. The control inputs are expressed in terms of their Fourier series expansions, so that a numerical solution can be easily obtained. The algorithm deals directly with the transcendental transfer functions from control inputs to outputs of interest, and structural deformation penalties, as well as penalties on control effort, are included in the formulation. The algorithm is applied to several structures of increasing complexity to show its generality
One Nation, Under Fraud: A Remonstrance
This Remonstrance presents a counter-cultural narrative and analysis of Maine’s legal, political, economic, and social interactions with the Wabanaki people. Although contemporary indicia of abuses by the State are glaringly obvious, a cohesive modern narrative that incorporates Maine’s history of predation upon and mistreatment of the tribes has remained poorly defined from an historico-legal perspective. Presenting its analysis through an historic, legal, political, economic, and social nexus, this Remonstrance traces the ontogeny of control exerted by the State of Maine over the Wabanaki tribes and endeavors to excavate the hidden historical narrative of the calculated politico-legal regime that has for two-hundred years driven the State’s coercive policies. In so doing, this Remonstrance examines the economic imperatives of the early American and Maine governments and the outgrowth of policies aimed at generating wealth from the stolen resources of Wabanaki tribal lands through an in-depth analysis of the transcripts of the legislative hearings (referred to here as the “Indian Papers”) that led to the commissioning of the Proctor Report of 1942.These Indian Papers are undeniable primary evidence memorializing the strategy the State undertook to affect a regime of isolation, control, and elimination of the tribes. The Authors believe that the Indian Papers and other documents analyzed herein have been heretofore neglected as competent evidence of Maine’s conscious orchestration of coercive policies carried out and retroactively legitimized through fraudulent jurisprudence. Through critical analysis, the Authors arrive at the conclusion that not only did the State of Maine have actual knowledge and intent to thrust an illegitimate politico-legal regime of suppression upon the tribes, but—despite acknowledging its past bad acts—it consciously chose to adopt many of these same tactics more than one hundred years later
Pulling From the Ranks?: Remarks on the Proposed Use of an Objective Judicial Ranking System to Guide the Supreme Court Appointment Process
Properties of nonaqueous electrolytes Quarterly report, 20 Dec. 1966 - 19 Mar. 1967
Properties of nonaqueous electrolytes - preparation of electrolytes, nuclear magnetic resonance structural studies, and physical property determination
The Quantum Geometric Phase between Orthogonal States
We show that the geometric phase between any two states, including orthogonal
states, can be computed and measured using the notion of projective
measurement, and we show that a topological number can be extracted in the
geometric phase change in an infinitesimal loop near an orthogonal state. Also,
the Pancharatnam phase change during the passage through an orthogonal state is
shown to be either or zero (mod ). All the off-diagonal geometric
phases can be obtained from the projective geometric phase calculated with our
generalized connection
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