Introductory assessment of orbiting reflections for terrestrial power generation

The use of orbiting mirrors for providing energy to ground conversion stations to produce electrical power is shown to be a viable, cost effective and environmentally sound alternative to satellite solar power stations and conventional power sources. This is accomplished with the use of very light weight metal coated polymeric films as mirrors which, after deployment at 800 km, are placed in operational orbit and controlled by solar radiation pressure. Relations are developed showing the influence of a number of parameters (mirror altitude, orbit inclination, period, mirror size and number, and atmospheric effects) on the reflected insolation that may be received by a ground spot as a function of location. Some attractive alternative uses of the reflection are briefly discussed as a beneficial adjuncts to the system

Symmetry enhanced first-order phase transition in a two-dimensional quantum magnet

Theoretical studies of quantum phase transitions have suggested critical points with higher symmetries than those of the underlying Hamiltonian. Here we demonstrate a surprising emergent symmetry of the coexistence state at a strongly discontinuous phase transition between two ordered ground states. We present a quantum Monte Carlo study of a two-dimensional S=1/2 quantum magnet hosting the antiferromagnetic (AFM) and plaquette-singlet solid (PSS) states recently detected in SrCu2(BO3)2. We observe that the O(3) symmetric AFM order and the Z2 symmetric PSS order form an O(4) vector at the transition. The control parameter g (a coupling ratio) rotates the vector between the AFM and PSS sectors and there are no energy barriers between the two at the transition point gc. This phenomenon may be observable in SrCu2(BO3)2.First author draf

Measuring viscoelastic properties using compliant systems

An analysis of a novel indentation model has been implemented to obtain master curves describing the optimal experimental parameters necessary to achieve the highest possible accuracy in the determination of viscoelastic properties of soft materials. The indentation model is a rigid indenter driven by a compliant measurement system, such as an atomic force microscope or optical tweezers, into a viscoelastic half space. The viscoelastic material is described as a multiple relaxation Prony series. The results have been extended via an application of a viscoelastic equivalence principle to other physical models such as poroelasticity. Optimisation of the indentation parameters has been conducted over many orders of magnitude of the velocity, viscoelastic moduli, spring stiffness, relaxation times and the duration of indentation resulting in a characteristic master curve. It is shown that using sub-optimal conditions gives the appearance of a more elastic material than is actually the case. For a two term Prony series the ideal ramp duration was found to be approximately one eighth of the relaxation. Also the ideal ramp duration for a three term Prony series was determined and shown to guarantee distinct relaxation times under specific conditions

Aerodynamic characteristics determined during development of the Apollo launch escape vehicle configuration

Aerodynamic characteristics determined during development of Apollo launch escape vehicle configuration in wind tunnel test

Consequences of Reservoir Drainage on Downstream Water Chemistry, Suspended Sediment, and Nutrients, Southwest Missouri

Construction and subsequent draining of reservoirs can have dramatic affects on the release of nutrients and sediments to waterways. This study describes how the temporary draining of a small reservoir for dam repair influences downstream water quality. The Valley Mill Reservoir has a surface area of 6.1 hectares and volume of 150,000 m3 when filled. Water chemistry monitoring and water sampling were performed at six sites during baseflow and ten sites during runoff events for one year. Water samples were analyzed for total nitrogen (TN), total phosphorous (TP), and total suspended sediment (TSS) concentrations. Results indicate that draining of Valley Mill Reservoir caused only minor changes in water chemistry. However, reservoir drainage caused significant erosion of the exposed lake bed as well as the stream channel upstream of the reservoir. Increases in TSS lagged behind drainage but increased dramatically once drainage was complete. Mean TSS increased from 7.5 mg/L upstream of the reservoir to 20.7 mg/L in reservoir outflow during baseflow. During storm events, TSS increased over 100 percent to nearly 100 mg/L in the drained reservoir outflow, with a maximum concentration of 525 mg/L. The increase in TSS resulted in TP increases during baseflow and storm events, since TP is known to attach to sediment. Mean outflowing TP increased by 10 percent to 43 ug/L during baseflow and by 20 percent to 207 ug/L following storm events. Total nitrogen remained below 5 mg/L at all monitoring sites and decreased by 5 to 15 percent after flowing over the exposed lakebed. Therefore, draining of Valley Mill Reservoir may have caused degradation of water quality downstream of reservoir outflow due to large amounts of sediment and phosphorus being released from the drained reservoir

Spectroscopic and optical studies of a high pressure, underexpanded jet.

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/77279/1/AIAA-1966-164-356.pd