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Full-Text Articles in Mechanical Engineering
Reducing Orbit Covariance For Continuous Thrust Spacecraft Transfers, Scott Zimmer, Oscar Ocampo, Robert H. Bishop
Reducing Orbit Covariance For Continuous Thrust Spacecraft Transfers, Scott Zimmer, Oscar Ocampo, Robert H. Bishop
Mechanical Engineering Faculty Research and Publications
The calculus of variations is used to develop the necessary theory and derive the optimality conditions for a spacecraft to transfer between a set of initial and final conditions, while minimizing a combination of fuel consumption and a function of the estimation error covariance matrix associated with the spacecraft state. The theory is developed in a general manner that allows for multiple observers, moving observers, covariance associated with an arbitrary frame, a wide variety of observation types, multiple gravity bodies, and uncertainties in the spacecraft equations of motion based on the thrusting status of the engine. A series of example …
The Aerodynamics Of The Knuckleball Pitch: An Experimental Investigation Into The Effects That The Seam And Slow Rotation Have On A Baseball, Michael Patrick Morrissey
The Aerodynamics Of The Knuckleball Pitch: An Experimental Investigation Into The Effects That The Seam And Slow Rotation Have On A Baseball, Michael Patrick Morrissey
Master's Theses (2009 -)
There has been plenty of research on the fluid dynamic effects on different spheres, including sports balls, such as baseballs. Baseball pitches have different velocities, rotation rates and orientations which will cause the baseball to move in different directions. There has also been plenty of research on the aerodynamics of curveballs, but not nearly as much on knuckleballs. The difference between the two is that the knuckleball has a much slower rotation rate and a different initial orientation. This causes the baseball to "knuckle," or moving erratically. This pitch in baseball is one of the hardest to pitch, hit, catch, …
Inter-Frequency Bias Estimation For The Gps Monitor Station Network, Donny Holaschutz, Robert H. Bishop, R. Benjamin Harris, Brian Tolman
Inter-Frequency Bias Estimation For The Gps Monitor Station Network, Donny Holaschutz, Robert H. Bishop, R. Benjamin Harris, Brian Tolman
Mechanical Engineering Faculty Research and Publications
The inter-frequency bias (IFB) is present in all dual frequency combinations of GPS pseudorange and carrier phase observables. It is caused by the path dependent signal delays in both the satellite and receiver. That delay can be directly measured for a space vehicle prior to launch, or for a ground based receiver prior to its being used in the field. However the bias is known to drift, and monitoring the delay estimate by direct measurement is time consuming for ground based receivers and impossible for deployed space vehicles. Hansen (2002) examined the observability of IFB through a global model of …