199 research outputs found
Paper Session III-C - Solar Power in Space
The space program could not have existed without the solar cells and its twin, the transistor. Almost all satellites ever launched have relied on these two semiconductor devices to operate. Solar cells convert sunlight directly into electricity. No more than several hundred microns thick, they produce electricity without boilers, turbines, pipes and cooling towers. In fact, they work without moving parts. Photons, packets of energy from the sun, silently split loosely bound electrons in the solar material from their orbits. The solar cell’s intrinsic voltage pushes those liberated electrons in its vicinity to contacts where they flow through as electricity. The modularity of the technology called photovoltaics allows technicians to exactly fit the amount of solar cells to the application at hand whether requiring a milliwatt or megawatts of power
“Equality, I Spoke Th at Word/As If a Wedding Vow”: Mental Disability Law and How We Treat Marginalized Persons
Proportionality Review in New Jersey: An Indispensable Safeguard in the Capital Sentencing Process
Competency mapping framework for regulating professionally oriented degree programmes in higher education
Recognition of the huge variation between professional graduate degree programmes and employer requirements, especially in the construction industry, necessitated a need for assessing and developing competencies that aligned with professionally oriented programmes. The purpose of this research is to develop a competency mapping framework (CMF) in this case for quantity surveying honours degree programmes. The graduate competency threshold benchmark (GCTB) is a key component of the CMF. Therefore, the CMF contains the mapping process, the template documents and the benchmark. The research adopted literature review, pilot study, case studies (including semi-structured interviews) and expert forum in developing the framework. The framework developed in this research provides new insight into how degree programmes map against competencies. Thus, the framework can be applied more widely, to other professional degree programmes, for monitoring and improving the quality and professional standards of construction degree programmes by accrediting bodies. This should connect construction graduates more effectively to the industry
Does Chlorhexidine Bathing in Adult Intensive Care Units Reduce Blood Culture Contamination? A Pragmatic Cluster-Randomized Trial
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A modified law-of-the-wall applied to oceanic bottom boundary layers
Near the bottom, the velocity profile in the bottom boundary layer over the continental
shelf exhibits a characteristic law-of-the-wall that is consistent with local estimates of
friction velocity from near-bottom turbulence measurements. Farther from the bottom, the
velocity profile exhibits a deviation from the law-of-the-wall. Here the velocity gradient
continues to decrease with height but at a rate greater than that predicted by the law-of-the-wall
with the local friction velocity. We argue that the shape of the velocity profile is
made consistent with the local friction velocity by the introduction of a new length scale
that, near the boundary, asymptotes to a value that varies linearly from the bottom. Farther
from the boundary, this length scale is consistent with the suppression of velocity
fluctuations either by stratification in the upper part of the boundary layer or by proximity
to the free surface. The resultant modified law-of-the-wall provides a good representation
of velocity profiles observed over the continental shelf when a local estimate of the
friction velocity from coincident turbulence observations is used. The modified law-of-the-
wall is then tested on two very different sets of observations, from a shallow tidal
channel and from the bottom of the Mediterranean outflow plume. In both cases it is
argued that the observed velocity profile is consistent with the modified law-of-the-wall.
Implicit in the modified law-of-the-wall is a new scaling for turbulent kinetic energy
dissipation rate. This new scaling diverges from the law-of-the-wall prediction above 0.2D
(where D is the thickness of the bottom boundary layer) and agrees with observed profiles
to 0.6D
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Convectively Driven Mixing in the Bottom Boundary Layer
Closely spaced vertical profiles through the bottom boundary layer over a sloping continental shelf during relaxation from coastal upwelling reveal structure that is consistent with convectively driven mixing. Parcels of fluid were observed adjacent to the bottom that were warm (by several millikelvin) relative to fluid immediately above. On average, the vertical gradient of potential temperature in the superadiabatic (statically unstable) bottom layer was found to be −1.7 × 10⁻⁴ K m⁻¹, or 6.0 × 10⁻⁵ kg m⁻⁴ in potential density. Turbulent dissipation rates (ε) increased toward the bottom but were relatively constant over the dimensionless depth range 0.4–1.0z/D (where D is the mixed layer height). The Rayleigh number Ra associated with buoyancy anomalies in the bottom mixed layer is estimated to be approximately 10¹¹, much larger than the value of approximately 10³ required to initiate convection in simple laboratory or numerical experiments. An evaluation of the data in which the bottom boundary layer was unstably stratified indicates that the greater the buoyancy anomaly is, the greater the turbulent dissipation rate in the neutral layer away from the bottom will be. The vertical structures of averaged profiles of potential density, potential temperature, and turbulent dissipation rate versus nondimensional depth are similar to their distinctive structure in the upper ocean during convection. Nearby moored observations indicate that periods of static instability near the bottom follow events of northward flow and local fluid warming by lateral advection. The rate of local fluid warming is consistent with several estimates of offshore buoyancy transport near the bottom. It is suggested that the concentration of offshore Ekman transport near the bottom of the Ekman layer when the flow atop the layer is northward can provide the differential transport of buoyant bottom fluid when the density in the bottom boundary layer decreases up the slope
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Atmospheric forcing of the Oregon coastal ocean during the 2001 upwelling season
Meteorological conditions during an intensive oceanographic observational program
in May through August 2001 along the central Oregon coast are described and related to
larger-scale and longer-term conditions. Southward wind stresses of 0.05-0.1 N m⁻²
occurred roughly 75% of the time, with a sustained period of dominantly southward stress
from mid-June through July. Wind variations were correlated with variations in the large-scale
Aleutian Low and North Pacific High pressure centers; correlations with the
continental Thermal Low were small. Intraseasonal oscillations in alongshore wind stress
(periods near 20 days) correlated with the north-south position of the jet stream. These
stress oscillations drove 20 day oscillations in upper ocean temperature, with a lag of
roughly 5 days for maximum correlation and amplitudes near 4°C. The sum of sensible
and latent air-sea heat fluxes was generally into the atmosphere through June, then weakly
into the ocean thereafter, with fluctuations on synoptic timescales. Semidiurnal
fluctuations in surface air temperature were observed at two northern moorings, apparently
forced indirectly by nonlinear internal ocean tides. The diurnal cycle of wind stress
was similar for both southward and northward wind conditions, with the diurnal
alongshore fluctuation southward in the evening and northward in the morning. During
southward winds the marine atmospheric boundary layer (MABL) was typically defined
clearly by a strong temperature inversion, and a shallow stable internal boundary layer
often formed within the MABL over cool upwelled waters, with surface air temperature
roughly 1°C lower inshore than offshore. During northward winds, essentially no
low-level temperature stratification was observed.Keywords: coastal meteorology, air‐sea interactions, coastal upwellin
Arginine–glycine–aspartic acid functional branched semi-interpenetrating hydrogels
For the first time a series of functional hydrogels based on semi-interpenetrating networks with both
branched and crosslinked polymer components have been prepared and we show the successful use of
these materials as substrates for cell culture. The materials consist of highly branched poly(N-isopropyl
acrylamide)s with peptide functionalised end groups in a continuous phase of crosslinked poly(vinyl
pyrrolidone). Functionalisation of the end groups of the branched polymer component with the GRGDS
peptide produces a hydrogel that supports cell adhesion and proliferation. The materials provide a new
synthetic functional biomaterial that has many of the features of extracellular matrix, and as such can be
used to support tissue regeneration and cell culture. This class of high water content hydrogel material
has important advantages over other functional hydrogels in its synthesis and does not require postprocessing
modifications nor are functional-monomers, which change the polymerisation process,
required. Thus, the systems are amenable to large scale and bespoke manufacturing using conventional
moulding or additive manufacturing techniques. Processing using additive manufacturing is exemplified
by producing tubes using microstereolithography
Wave-current interaction in Willapa Bay
Author Posting. © American Geophysical Union, 2011. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 116 (2011): C12014, doi:10.1029/2011JC007387.This paper describes the importance of wave-current interaction in an inlet-estuary system. The three-dimensional, fully coupled, Coupled Ocean-Atmosphere-Wave-Sediment Transport (COAWST) modeling system was applied in Willapa Bay (Washington State) from 22 to 29 October 1998 that included a large storm event. To represent the interaction between waves and currents, the vortex-force method was used. Model results were compared with water elevations, currents, and wave measurements obtained by the U.S. Army Corp of Engineers. In general, a good agreement between field data and computed results was achieved, although some discrepancies were also observed in regard to wave peak directions in the most upstream station. Several numerical experiments that considered different forcing terms were run in order to identify the effects of each wind, tide, and wave-current interaction process. Comparison of the horizontal momentum balances results identified that wave-breaking-induced acceleration is one of the leading terms in the inlet area. The enhancement of the apparent bed roughness caused by waves also affected the values and distribution of the bottom shear stress. The pressure gradient showed significant changes with respect to the pure tidal case. During storm conditions the momentum balance in the inlet shares the characteristics of tidal-dominated and wave-dominated surf zone environments. The changes in the momentum balance caused by waves were manifested both in water level and current variations. The most relevant effect on hydrodynamics was a wave-induced setup in the inner part of the estuary.Primary funding for this study was furnished
by the U.S. Geological Survey, Coastal and Marine Geology Program,
under the Carolinas Coastal Change Processes Project.2012-06-1
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