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 44 for “"delta-V"”.
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On-orbit satellite inspection : navigation and [Delta]v analysis
… A detailed angles-only navigation analysis and [delta]v performance analysis of three different inspection trajectories are performed. The results of this analysis show the feasibility of angles-only rendezvous navigation and the over-all inspection satellite concept while validating the …
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Interplanetary Transfer Trajectories Using the Invariant Manifolds of Halo Orbits
… But these missions required large amounts of delta-v for their maneuvers and therefore large amounts of fuel mass. As we desire to travel farther and more extensively in space, these two-body dynamics lead to impossibly high delta-v values, and missions become infeasible due to the massive …
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Evaluation of event data recorders in real world crashes and full-scale crash tests
… performed well in staged crash tests reporting delta-V accurately in five of six tests. They were able to report other crash related parameters such as driver seat belt and airbag deployment status accurately in five of six tests as well.</p> <p>Comparison of EDRs with real world accident …
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Predicting Occupant Injury with Vehicle-Based Injury Criteria in Roadside Crashes
… significant advantage over the simpler delta-V crash severity metric in discriminating between serious and non-serious occupant injury. This finding underscores the importance of developing an improved vehicle-based injury metric. Based on an analysis of 619 full-scale frontal crash …
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The accuracy of energy-based crash reconstruction techniques using event data recorder measurements
… the field of accident investigation, a vehicle's delta-V is commonly used to quantify the severity of a collision. Delta-V is defined as the impulsive change in vehicle velocity caused by a collision. Often, the method used to obtain delta-Vs in real-world collisions is estimation based on …
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Reconfigurable Satellite Constellations for Mobile Target Tracking
… study observing Typhoon Megi using around 2 m/s delta-V, in comparison to similarly performing solutions previously found of around 13.5 m/s delta-V. The inclusion of an optimizer in maneuver planning enhances the prior work, exploring a continuous design space of possible maneuver options. This …
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Identifying near-earth asteroid targets for human exploration using particle swarm optimization
… that was developed minimizes the total mission delta-V, given a particular epoch date, whilst optimizing four time parameters, namely, the ideal time to launch from Earth, the outbound flight time from Earth to an asteroid, the stay time at the asteroid and the inbound flight time from the …
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Hybrid Chemical-Electric Propulsion Systems for CubeSats
… a high specific impulse, thus resulting in large delta-v budgets. While common for larger spacecraft to include both types of propulsion on-board, the stringent size, weight, and power constraints on CubeSat have mainly limited CubeSats to only one type of propulsion. However, the research and …
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Design and analysis of a stage-based electrospray propulsion system for CubeSats
… to Earth orbit due in part to the lack of high [delta]V propulsion systems that are compatible with the small form factor. The ion Electrospray Propulsion System developed at the Space Propulsion Laboratory at the Massachusetts Institute of Technology is a promising technology foundation for a …
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Injury Risk of Road Departure Crashes using Modeling and Reconstruction Methods
… modification increased the average estimated delta-V by 8% and reduced error from 23% to 13% on average. A method to extend the WinSmash energy-based reconstruction approach to poles and trees that were damaged or broken was implemented to provide delta-V estimates for these crashes. The error …
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Deep-Space Exploration Enabled by CubeSats with Staged Electrospray Propulsion
… operations are the high propulsion capabilities (delta-v) required to impart meaningful orbit change and the falloff of available solar power away from the Sun, e.g. by a factor of five to ten in the main asteroid belt. Practical high delta-v CubeSat propulsion comes exclusively from electric …
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Analysis of Low-Energy Lunar Transfers in a High-Fidelity Dynamics Model
… gravitational effects to reduce overall delta-v requirements, in some cases removing the capture delta-v completely. While the time of flight for these transfers can be much longer than a Hohmann-type transfer, the chaotic design space of these transfers can enable large changes in …
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Rendezvous approach guidance for uncooperative tumbling satellites
… is measured by the total velocity changes, or [delta]V, needed to complete the maneuvers. Cumulative [delta]V sensitivity is measured against navigational uncertainty in the rotational axis to summarize the key requirements and trade-offs associated with implementing this algorithm.
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A new guidance method for a DeltaV and re-entry constrained orbit transfer problem
… within one revolution. Constrained to a fixed [delta]V resulting from a two stage thrust profile, the spacecraft must execute a burn maneuver that can effectively dissipate energy to place it on a transfer orbit with previously unknown velocity requirements. Finally, the guidance strategy should …
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The hydrogen-induced piezoelectric effect in InP HEMTs
… been shown to cause a threshold voltage shift, [delta] V[sub]T. This is a serious reliability concern. This effect has been attributed to a H-induced piezoelectric effect. Formation of TiH[sub]x expands the Ti layer in the gate, causing mechanical stress in the underlying semiconductor. This …
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Sigma Ratings Case Study
… This case study focuses on MIT startup and delta v alumnus Sigma Ratings, a non-credit agency, founded in 2017 by Gabrielle Haddad and Stuart Jones Jr. It immerses the reader in the decision-making process of the company, after its business model revealed major flaws necessitating a pivot to …
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Orbital Optimization of Interplanetary Trajectories with Environmental Perturbations
… then used to evaluate the best combination of Delta V, time of flight, synodcity, flyby altitude, and heliocentric energy. This work is primarily concerned with adding the dynamics created by perturbations into Lambert's problem as well as the gravity assist trajectories. The improved analysis …
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Semiclassical asymptotics for the scattering amplitude in the presence of focal points at infinity
… by the Schr\"odinger operator $P(h)=-h^2\Delta+V$, where $V$ is a short-range potential. With the aid of Maslov theory, we give a geometrical formula for the semiclassical asymptotics as $h\to 0$ of the scattering amplitude $f(\omega_-,\omega_+;\lambda,h)$ $\omega_+\neq\omega_-$) which …
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Analisi tridimensionale priva di contatto delle ulcere cutanee laser assistita
… nessuno di questi valori ne' valori derivati ( delta V /delta A; Delta V/ Delta P) alla guarigione a 6 mesi. Secondo le analisi da noi effettuate, sebbene con l'incertezza derivata da un gruppo ridotto di pazienti, la guarigione delle lesioni ulcerative venose non è predicibile a 6 mesi …
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The Potential of Event Data Recorders to Improve Impact Injury Assessment in Real World Crashes
… vehicle-based crash severity metrics relative to delta-v. This dissertation firstly assessed the capabilities of EDRs. Chapter 2 demonstrated the accuracy of 176 crash tests, corresponding to 29 module types, 5 model years, 9 manufacturers, and 4 testing configurations from 2 regulatory agencies. …
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