Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 39 for “"Minimum-fuel"”.
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Minimum Time/Minimum Fuel Control of an Axisymmetric Rigid Body
… to reorient an aerial vehicle during flight in a minimum time or minimum fuel fashion. This thesis will present a minimum time/fuel control solution to reorienting an axisymmetric rigid body using eigenaxis maneuvers. Any fixed desired attitude can be achieved by rotating the rigid body about its …
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Piecewise-constant control strategies for use in minimum fuel aeroassisted orbital transfers
… certain orbital transfers can greatly reduce the fuel consumption as compared with corresponding all-propulsive transfers. Therefore, in seeking minimum fuel trajectories, aeroassisted transfers need to be investigated. A review of the current literature indicates that such problems have been …
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A homotopy approach to the solutions of minimum-fuel space-flight rendezvous problems
… the space-flight rendezvous problem including a minimum radius constraint is developed, which can naturally deform any initial problem into some other valid desired problem. Several coplanar and non-coplanar solutions for circular and elliptic cases have been presented for the restricted time …
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Parameter optimization of atmospheric skip trajectories for use in minimum fuel usage transfer orbits
… the complexity of the desired skip trajectory. Fuel optimal transfer orbits are obtained using the generalized impulse along with Keplerian arcs and instantaneous changes in velocity. Families of coplanar and noncoplanar transfers for circular orbit to circular orbit are numerically generated. …
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Analysis of Infinite Domain Criticality Zones in Finite Reactors (Uniform Power, Minimum Fuel Density, Exact Solutions, Poles of Bromwich Integral, Reduction of Pde's)
… the power are uniform throughout, and (2) the fuel density needed for criticality is minimum. A finite reactor loaded in this way would be subcritical and would have to contain additional fuel to compensate for neutron leakage to sustain criticality.
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The investigation and selection of a Venturi mixing tube to obtain, with the minimum fuel pressure, the proper proportion of kerosene vapor and air for combustion in a Stanley Steam Car
Thesis (B.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1920
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Multidisciplinary Design Optimization of a Medium Range Transonic Truss-Braced Wing Transport Aircraft
… Both configurations exhibit reduced weight and fuel consumption. Configurations are also optimized for 1990's or advanced technology aerodynamics. For the 1990's technology minimum TOGW cases, the SBW and TBW configurations achieve reductions in the TOGW of as much as 6% with 20% less fuel …
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Application of control theory to large flexible structures using the Independent Modal-Space Control method
… matrix, guaranteeing system controllability. The minimum-fuel problem is a very important one in the design of various space structures. Solution of the minimum-fuel problem is feasible in a coupled form for a fourth order system at most, but will be of insurmountable computational difficulty in …
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Incorporation of location-specific parameters and policy incentives in the Techno-Economic Analysis (TEA) of biorefineries
Biofuels will be an important part of a successful bioeconomy and the transition to renewable sources of energy. For this reason, various programs and incentives have been implemented at the federal and state levels to stimulate the production of biofuels from various feedstocks. New feedstocks and …
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Optimal variable-specific-impulse trajectories in simple gravitational fields
Minimum-fuel trajectories in the Clohessy-Wiltshire orbital model are investigated. Low-thrust variable-specific-impulse propulsion is assumed. The necessary conditions for an optimal solution and the equations of motion are combined to produce a single equation. Every solution to this equation is …
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Optimal cooperative power-limited rendezvous
Minimum-fuel rendezvous of two power-limited low-thrust spacecraft is investigated. Both vehicles are active and provide thrust to complete the rendezvous. Total propellant consumption is minimized. Two gravitational field models are investigated: the Clohessy-Wiltshire linearized field and the …
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Fuel-optimal space-flight transfer solutions through a redundant adjoint variable transformation
A transformation between minimum dimension adjoint variables and redundant adjoint variables is derived in this dissertation. The transformation is then applied between the adjoint variables associated with Cartesian position and velocity vectors and a set of redundant adjoint variables associated …
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Cooperative Power-Limited Optimal Rendezvous Between Many Spacecraft
<p>The minimum fuel rendezvous problem between several power-limited low-thrust spacecraft neighboring either a circular or an elliptic orbit is investigated. Both cooperative and non cooperative maneuvers are studied. The maximum principle of Pontryagin is applied to the optimal control rendezvous …
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Six degree of freedom optimal trajectories for satellite rendezvous
A method is developed for computing the minimum fuel trajectory for a satellite that moves between two different positions and orientations using a sequence of impulsive burns. The method makes use of the linear Clohessy-Wiltshire equations to describe translational motions, Euler's equations of …
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Optimal cooperative time-fixed impulsive rendezvous
… has been developed for determining optimal, i.e. minimum fuel, trajectories for the fixed-time cooperative rendezvous of two spacecraft. The method assumes that the vehicles perform a minimum of three impulsive maneuvers with each vehicle being active, that is, making at least one maneuver. The …
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Optimal, impulsive, direct ascent, time-fixed orbital interception
… the optimal impulsive trajectories is applied to minimum fuel, direct ascent, time-fixed intercept trajectories. The optimal trajectory is obtained by satisfying Lawden's necessary conditions expressed in terms of the primer vector. The vehicle is initially at rest on the surface of a spherical …
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Optimal control techniques for multimode propulsion mission design in cislunar space
… types of optimal control problems are solved: minimum-fuel and propellant-constrained minimum-time (PCMT). The former is the primary focus of this dissertation and examples are shown for interplanetary, geocentric, and cislunar transfers for systems with large performance differences (i.e., …
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Techno-economic and life cycle analysis of the conversion of natural gas and biomass to hydrogen and performance carbons
… methane pyrolysis process achieves the lowest minimum fuel selling price (MFSP) for hydrogen production, while the gasification process incurs the highest production costs. The integrated processes are economically feasible if carbon nanotubes (CNTs) are sold for $2.5/kg or higher. …
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Optimal, impulsive, time-fixed orbital rendezvous and interception with path constraints
Minimum-fuel, impulsive, time-fixed extremal solutions are obtained for the problem of orbital rendezvous and interception with path constraints. The coplanar case and a restricted class of path constraints are analyzed. A theory based on the extended problem of Bolza in the calculus of variations …
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Constrained trajectory optimization of a soft lunar landing from a parking orbit
… based constraints on the behavior of the minimum fuel trajectory, has been completed. Metrics of trajectory evaluation included fuel expenditure, terminal attitude, thrust histories, etc.. The vehicle was initialized in a circular parking orbit and the trajectory divided into three …
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