The development of resistance measurement techniques is very important for characterization of future nanoelectronics. Pulsed IV measurement techniques are very useful for accurate resistance measurements on nanoscale samples because of the efficient removal of e.g. EMF errors. In the project we have designed a pulsed IV-setup based on a state-of-the art current source (6221) and nanovoltmeter (2182A) from Keithley, and used the setup for resistance measurements on ferromagnetic samples. Two different samples were investigated using the pulsed IV system – ferromagnetic wires with a central nanoconstriction and amorphous microwires. We have tested the pulse delta system with different pulse widths, duty cycles and voltage levels. The results show a successful integration of the setup. From the measurement results we confirm that the pulse delta system provides accurate measurements with a low noise of about 0.02Ω. The resistance of the samples increases approximately quadratically with bias which is interpreted as a heating effect due to the very high current density of about 107A∙cm-2.

This thesis evaluates mission scenarios using the existing Evolved Expendable Launch Vehicles for delivering the Crew Exploration Vehicle to the International Space Station. The Space Shuttle is scheduled to retire in the year 2011 and the Ares I is being developed to replace it. With its current schedule, the earliest that the Ares I will become fully operational is 2016. The configurations in this thesis are presented to narrow the gap in which the USA does not have direct access to the International Space Station. They also present "buy down" options for the USA human space operations, if the current development issues of the Ares I cause it to not become operational at all. The three Launch options presented are the Atlas V HLV, the Delta IV Heavy, and the Delta IV with three common core boosters as the first stage and the Orion service module to be used as the second stage. The first configuration, the Atlas V HLV requires significant impulse from the Orion service module in order to reach the final International Space Station orbit. The second option, the Delta IV Heavy, launches the Orion as a passive payload and requires no impulsive maneuvering from the service module in order to reach the International Space Station orbit. The third configuration, the Delta IV Heavy with three common core boosters as the first stage, and the Orion spacecraft acting as the second stage, requires significant impulse from Orion's service module engine to achieve the International Space Station orbit. After final orbit insertion all three configurations still have sufficient propellent for de-orbit and re-entry.The third configuration has a certain appeal, by eliminating the second stage only the common core booster on the Delta IV Heavy system need be human-rated. Finally, reliability and development cost assessments are presented and compared to the Ares I.

During the launch sequence of the United Launch Alliance Delta IV launch vehicle, large amounts of pure hydrogen are introduced into the launch table and ignited by Radial-Outward-Firing-Igniters (ROFIs). This ignition results in a significant flame, or plume, that rises upwards out of the launch table due to buoyancy. The presence of the plume causes increased and unwanted heat loads on the surface of the vehicle. A proposed solution is to add a series of fans and structures to the existing launch table configuration that are designed to inject ambient air in the immediate vicinity of the launch vehicle's nozzles to suppress the plume rise. In addition to the air injection, secondary fan systems can be added around the launch table openings to further suppress the hydrogen plume. The proposed air injection solution is validated by computational fluid dynamics simulations that capture the combustion and compressible flow observed during the Delta IV launch sequence. A solution to the hydrogen plume problem will have direct influence on the efficiency of the launch vehicle: lower heat loads result in thinner vehicle insulation and thus allow for a larger payload mass. Current results show that air injection around the launch vehicle nozzles and air suppression around the launch table openings significantly reduces the size of the plume around the launch vehicle prior to liftoff.