Admittance Dependence of the Infinite Cylindrical Antenna Upon Exciting Gap Thickness

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/116082/1/rds19672121431.pd

Electromagnetic Wave Scattering From a Cylinder Immersed in a Warm Plasma

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/116074/1/rds19672121411.pd

The Effect of Temperature, Moisture Content and Latex Particle Size on Latex Coating Gloss

This thesis involved the study of the effects on gloss of moisture, temperature, and particle size of styrene butadiene bound pigmented coatings. Variables investigated were substrate absorbancy, latex particle size, moisture content and calendar stack temperature. Substrate absorbancy was varied by comparing an unsized 70 g/m 2 paper base sheet to a polymer drafting film (mylar). Latex particle size was varied by method of emulsion manufacture so that each was uniform and monodispersed. Moisture content was varied by allowing the sheets to come to equilibrium in a room where the humidity was changed. The temperature of the calendar stack was changed with an electric heating coil. An Ircon infrared temperature recorder was used to monitor the stack temperature. It was found that an increase in calendar stack temperature increased coating gloss for all cases studied. The statistical analysis of data obtained in this study showed moisture content significantly interacted with temperature such that coating gloss could be adversely affected at the lower temperatures studied. For the higher temperatures studied, increases in moisture content always led to increases in coating gloss. Coating opacity was found to decrease with increasing temperature and/or increasing moisture content. It is recommended that since this study showed temperature and moisture content. It is recommended that since this study showed temperature and moisture content significantly interacted to effect the development of styrene-butadiene bound pigmented coating gloss, that further studies similar in scope to this one be conducted on other binders used in the coating industry

Dynamics and Control of Tethered Formation Flight Spacecraft Using the SPHERES Testbed

This paper elaborates on the theory and experiment of controlling tethered spacecraft formation without depending on thrusters. In dealing with such underactuated systems, much emphasis is placed on complete decentralization of the control and estimation algorithms in order to reduce the dimensionality and complication. The nonlinear equations of motions of multi-vehicle tethered spacecraft are derived by Lagrange’s equations. Decentralization is then realized by the diagonalization technique and its stability is proven by contraction theory. The preliminary analysis predicts unstable dynamics depending on the direction of the tether motor. The controllability analysis indicates that both array resizing and spin-up are fully controllable only by the reaction wheels and the tether motor, thereby eliminating the need for thrusters. Based upon this analysis, gain-scheduling LQR controllers and nonlinear controllers by feedback linearization have been successfully implemented into the tethered SPHERES testbed, and tested at the NASA MSFCs flat floor facility using two and three SPHERES configurations. The relative sensing mechanism employing the ultrasound ranging system and the inertial gyro is also described