An improved dual-frequency technique for the remote sensing of ocean currents and wave spectra

A two frequency microwave radar technique for the remote sensing of directional ocean wave spectra and surface currents is investigated. This technique is conceptually attractive because its operational physical principle involves a spatial electromagnetic scattering resonance with a single, but selectable, long gravity wave. Multiplexing of signals having different spacing of the two transmitted frequencies allows measurements of the entire long wave ocean spectrum to be carried out. A new scatterometer is developed and experimentally tested which is capable of making measurements having much larger signal/background values than previously possible. This instrument couples the resonance technique with coherent, frequency agility radar capabilities. This scatterometer is presently configured for supporting a program of surface current measurements

Gear Ratios in the Ankle-Foot System

Gear ratios in locomotion can be defined as the ratio of lever arms between the ground reaction force (GRF) and the calf muscle to the ankle joint. A resultant change in torque can be developed by either lengthening the distance of the GRF arm, or by altering the direction of the GRF. Studies on sports equipment such as speed skating and bicycling have shown that altering the gear ratios can affect performance. The purpose of this study was to investigate the effects of gear ratios on ankle joint moment and power generation. Seven male subjects participated in the study (US size 9). Each subject performed sprints out of blocks in three conditions: a control, and two modified shoe conditions with carbon plate insoles inserted, one size 9 and one of size 11 adjusted to fit a size 9 runner. Kinematic and kinetic data were collected from the first stride out of the blocks and used to calculate ankle angle, torque, velocity and power. In a separate session, isometric and isokinetic measurements of the ankle plantarflexor strength were made in order to establish the torque-angle and torque-velocity relationships for each individual. Results showed that stiffening the sprint spike increased the gear ratio about the ankle. A larger torque was generated, mainly due to the shift in ankle range of motion toward a more dorsiflexed position. This can be supported by the torque-angle relationship determined from isometric strength measurements. Angular velocity decreased, offsetting the torque increase. As the result, no significant changes in power and energy produced were observed. Looking at individual results, two subjects showed a large increase in torque generation without decreasing angular velocity resulting in increased power, which is valued as increased sprinting performance, with a larger gearing ratio

Numerical modelling of heat generated by electroosmotic flows in micro-channels

This paper was presented at the 2nd Micro and Nano Flows Conference (MNF2009), which was held at Brunel University, West London, UK. The conference was organised by Brunel University and supported by the Institution of Mechanical Engineers, IPEM, the Italian Union of Thermofluid dynamics, the Process Intensification Network, HEXAG - the Heat Exchange Action Group and the Institute of Mathematics and its Applications.In this paper, numerical modeling of Joule heating in electroosmotic flows is described in some detail. The finite element method is used for the spatial discretization along with the characteristic based split (CBS) time discretization. A new non-dimensional scaling is also introduced. In addition to standard problems of micro channel flows, flow and heat generation in a T-mixer are also discussed in this paper

Sources and Characteristics of Liquid Process Wastes From Arctic Offshore Hydrocarbon Exploration

Increased interest in offshore hydrocarbon exploration in Arctic waters raises concern regarding liquid waste management from drilling operations. The typical sources of process liquid waste from exploratory drilling operations is described and data on the quantity and quality of liquid waste discharges is provided from monitoring at two offshore sites. The chemical and toxicological characteristics of the waste fluids indicate that a potential exists for water pollution in specific circumstances. However, close process control to reduce the quantities of waste fluid generated and judicious selection of drilling mud additives should prevent the occurrence of significant water pollution problems from waste fluid disposal at exploratory Arctic offshore drilling operations

Unconventional Hall effect in oriented Ca3_3Co4_4O9_9 thin films

Transport properties of the good thermoelectric misfit oxide Ca$_3$Co$_4$O$_9$ are examined. In-plane resistivity and Hall resistance measurements were made on epitaxial thin films which were grown on {\it c}-cut sapphire substrates using the pulsed laser deposition technique. Interpretation of the in-plane transport experiments relates the substrate-induced strain in the resulting film to single crystals under very high pressure ($\sim$ 5.5 GPa) consistent with a key role of strong electronic correlation. They are confirmed by the measured high temperature maxima in both resistivity and Hall resistance. While hole-like charge carriers are inferred from the Hall effect measurements over the whole investigated temperature range, the Hall resistance reveals a non monotonic behavior at low temperatures that could be interpreted with an anomalous contribution. The resulting unconventional temperature dependence of the Hall resistance seems thus to combine high temperature strongly correlated features above 340 K and anomalous Hall effect at low temperature, below 100 K.Comment: Submitted to Physical Review B (2005

Coverage-dependent adsorption sites for K/Cu(001) and Cs/Cu(001) determined by surface X-ray diffraction

Surface X-ray diffraction has been used to analyze in situ the room-temperature adsorption behaviour and the structure of K and Cs on Cu(100) at submonolayer coverages. Adsorption of K takes place in fourfold hollow sites up to coverages of about 0.25 monolayers (ML), where 1 ML corresponds to 1.53 × 1015 atoms/cm2. At higher coverages the formation of a quasi-hexagonal incommensurate adlayer is observed. In contrast, for Cs adsorption we observe from the very beginning the formation of the quasi-hexagonal structure up to the completion of the adlayer at about 0.30 ML. For K adsorption in the hollow sites we determine an adsorption height, d = 2.25(15) Å, corresponding to an effective K radius of reff = 1.6(1) Å close to the ionic radius of 1.33 Å. We do not observe a change in the effective radius as a function of coverage. For the quasi-hexagonal Cs structure we find an (average) adsorption height d = 2.94 Å corresponding to an effective radius of reff = 2.18 and 1.93 Å, for the limiting ca hollow- and bridge-site adsorption, respectively. The analysis of the superlattice reflections corresponding to the quasi-hexagonal incommensurate structures indicated that the K adlayer is strongly modulated. The first Fourier component of the substrate-induced modulation was determined to u01 = 1.29(3) Å. In contrast, for Cs/Cu(001) static modulation is much less important (u01 0.2 Å). Variation of the Cs adlayer density by changing the substrate temperature allows continuous expansion and contraction of the adsorbate unit cell. No commensurate-incommensurate transition has been observed

An information adaptive system study report and development plan

The purpose of the information adaptive system (IAS) study was to determine how some selected Earth resource applications may be processed onboard a spacecraft and to provide a detailed preliminary IAS design for these applications. Detailed investigations of a number of applications were conducted with regard to IAS and three were selected for further analysis. Areas of future research and development include algorithmic specifications, system design specifications, and IAS recommended time lines