343 research outputs found
Functionalisation of bolaamphiphiles with mononuclear bis(2,2'-bipyridyl)ruthenium(II) complexes for application in self assembled monolayers
A novel ruthenium(II) polypyridyl complex connected competently to a bolaamphiphile, containing amide linkages to provide rigidity via hydrogen bonding in the monolayer, has been prepared. The ruthenium(II) complexes of this ligand and of the intermediates in the synthesis were prepared by modification of the coordinated ligands, demonstrating the synthetic versatility and robustness of this family of complexes. All ruthenium complexes were characterised by electrochemical and spectroscopic techniques and were found to have similar properties to the parent complex [Ru(bipy)[3]][2][+], and remain versatile photosensitisers, with well-defined properties, despite extensive substitution of the bipy ligand
Optimizing Electrodynamic Tether System Performance
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76123/1/AIAA-2009-6734-525.pd
Electrodynamic Tether System Analysis Comparing Various Mission Scenarios
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76450/1/AIAA-2005-4435-964.pd
A Comparison of Laboratory Experimental and Theoretical Results for Electrodynamic Tether Electron Collection Performance for Some Bare Tether Geometries
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76910/1/AIAA-2009-6659-508.pd
Electron Emission for Electrodynamic Tether Systems in Space
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76291/1/AIAA-2004-3495-765.pd
Theory and Experimental Evaluation of Electrodynamic Tether Systems and Related Technologies.
The unique work presented in this thesis will first focus on integration of the latest theoretical and experimental electrodynamic aspects of an electrodynamic tether (EDT) into a time-independent simulation tool. Numerous elements have then be compared on a system level, including passive electron collection (or active ion emission) technologies, active electron emission technologies, bare versus insulated tether scenarios, boosting and de-boosting conditions, and various system element configurations. These results indicate that in many cases bare tether anodes are the optimal electron collection mechanism. In addition, it was shown that while hollow cathodes may be the best active electron emission technique, field emitter arrays result in less than 1% difference in system thrusting and use no consumables. This is based on the assumption that several-amp field emitter arrays can be built eventually.
Issues that have troubled previous systems are the efficiency at which the tether collects current, the total surface area, and the bare tether geometry. Experimental work was conducted to compare the effects of porous flat-tape tether geometries to those of slotted and solid geometries. The experiment investigated these different tether configurations to better understand the physics involved and how to apply the different tether geometries to an EDT system. This work has resulted in evidence showing that, regardless of the orientation of the probe with respect to the flowing plasma, equivalent mass holed tapes outperform that of slotted tapes. These slotted tapes, in turn, outperform solid tapes on an equivalent mass basis.
Modeling of hollow cathodes and other ion emission technologies has been a key concern to EDT technology and will have great implications to EDT systems. As tether systems venture outside of the ionosphere, there will likely need to be an alternate method for collecting electrons. An initial investigation using a hollow cathode as an electron collection source in the momentum exchange electrodynamic reboost (MXER) system was conducted. Results indicated that although this technology may produce a slight enhancement in thrust over a bare tether in altitudes over 1000 km, however, it requires too much consumable mass to be feasible.Ph.D.Electrical EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/57663/2/kfuhrhop_1.pd
System Analysis of the Expected Electrodynamic Tether Performance for the ProSEDS Mission
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76057/1/AIAA-2003-5096-440.pd
Measurement of Cross-Section Geometry Effects on Electron Collection to Long Probes in Mesosonic Flowing Plasmas
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/77060/1/AIAA-2003-4950-410.pd
Current Collection to Electrodynamic Tether Systems in Space
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/77109/1/AIAA-2004-5670-600.pd
Topological defects and shape of aromatic self-assembled vesicles
We show that the stacking of flat aromatic molecules on a curved surface
results in topological defects. We consider, as an example, spherical vesicles,
self-assembled from molecules with 5- and 6-thiophene cores. We predict that
the symmetry of the molecules influences the number of topological defects and
the resulting equilibrium shape.Comment: accepted as a Letter in the J. Phys. Chem.
- …