Application of proper orthogonal decomposition to the discrete Euler equations

The response of a fluid moving above a panel to localized oscillation of the panel is predicted using reduced‐order modelling (ROM) with the proper orthogonal decomposition technique. The flow is assumed to be inviscid and is modelled with the Euler equations. These non‐linear equations are discretized with a total‐variation diminishing algorithm and are projected onto an energy‐optimal subspace defined by an energy‐threshold criterion applied to a modal representation of time series data. Results are obtained for a bump oscillating in a Mach 1.2 flow. ROM is found to reduce the degrees of freedom necessary to simulate the flowfield by three orders of magnitude while preserving solution accuracy. Other observed benefits of ROM include increased allowable time step and robustness to variation of oscillation amplitude. Published in 2002 by John Wiley & Sons, Ltd.     

The emergence of social dominance in young boys' play groups: Developmental differences and behavior correlates.

This study examined relations among dominance, sociometric preference, and social behavior in groups of 1st- and 3rd-grade boys. 20 groups of 6 unacquainted boys met for 5 45-min semistructured play sessions on consecutive days. Sociometric interviews yielded daily social preference scores. Boys' social behaviors were coded from video records into discrete categories. Dominance hierarchies were formed on the basis of asymmetry (receiving vs initiating) of peer-directed aggression or persuasion attempts. Group-level results indicated that the least coherently organized groups were those containing younger boys and those in which aggression occurred at a high rate. Individual-level results indicated that dominance was associated with social preference to a greater degree among younger than older boys. Dominance was more highly related to leadership in older than younger boys. Implications of these findings are discussed with respect to the role of aggression in the social organization of boys' peer groups. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Hot Corrosion of Silica

The high-temperature corrosion of bulk silica glass was studied in pure oxygen and in SO₃-containing oxygen atmospheres in the presence of liquid sulfate deposits at temperatures of 700° and 1000°C. No reaction and devitrification were observed without Na₂SO₄ on the surface. The wetting of the silica by the sulfate, the tendency toward basic fluxing, and the crystallization of the silica incrased with the activity of Na₂O. The most extensive degradation of vitreous silica occurred by crystallization, and the resulting spalling under basic conditions and thermal cycling at basic conditions were parabolic. This behavior is explained by a model in which the crystallization is controlled by sodium at the glass-crystal interface and its diffusion into the glass. This sodium diffuses into the glass before crystallization and is swept ahead of the crystallization front.     

Ecological perspectives on regulation and water allocation for the Ord River,Western Australia

Water management agencies throughout Australia are attempting to find a balance between the water requirements of ecological and socio‐economic environments as part of a holistic approach to managing flow‐dependent river ecosystems. Environmental water provisions are under consideration for the Ord River in far northern Western Australia. This river has been regulated for irrigation and there are plans for substantial expansion. Like other semi‐arid and tropical rivers, however, the hydrology of the Ord River is highly variable and unpredictable, and therefore, proportionate water release strategies for the environment that are based on average monthly flows are unsuitable. Regulation continues to produce pronounced ecological changes throughout the river system as the impacts of flow regime are negated. There is a dichotomy in optimal flow regimes for the contrasting management aspirations of ecological restoration based on low seasonal flows, and the dilution flows required for the drainage of agricultural effluent. Whilst current agricultural land and water management practices continue, the two cannot coincide, and consequently, a decision should be made regarding which environmental water allocation holds the primary value. Such a decision would guide the appropriate dry season flow regime on the lower Ord River. Copyright © 2002 John Wiley & Sons, Ltd.     

Child care history and kindergarten adjustment.

Parents gave histories of 589 children just before kindergarten. Children were later assessed with teacher, peer, and observer measures of social adjustment in school. Children with higher day-care amounts in each of 3 eras (0–4, and 4–5 yrs) scored higher on the composite negative adjustment and lower on positive adjustment (however, they also scored lower on teacher-rated internalizing problems). Day care predicted even after statistical control for measures representing alternative explanations, such as family stress and socioeconomic status, accounting for 2.7% of variance in negative adjustment and 2.9% of positive adjustment. Interactions between day care and other variables did not add to predictions of the molar adjustment composites. Extensive infancy care did not in itself predict adjustment, according to planned contrasts that controlled for total amount of day care received across the 3 eras of the child's life. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Modelling of degradation of nickel-pigmented aluminium oxide photothermal collector coatings

Thermal degradation phenomena occurring in nickel-pigmented aluminium oxide coatings were investigated by combining detailed microstructural analysis with modelling of the optical properties. Scanning electron microscopy and Auger electron spectroscopy sputter profiling showed that the initial film consisted of a nickel-pigmented aluminium oxide layer close to the substrate. This layer supported a porous aluminium oxide layer that had a rough outer surface. While the solar absorptance degraded substantially (from 0.94 to 0.71) after heat treatment at 350°C for tens of hours, the aluminium oxide film morphology and thickness remained virtually unchanged and there was apparently no redistribution of nickel within the coating. Instead, the optical quality of the film degraded through oxidation of the nickel particles. These observations were supported by an optical model of the coating which produced the spectral reflectance properties measured both before and after the thermal ageing.     

Drugs and immunity: cannabinoids and their role in decreased resistance to infectious disease

Marijuana, Cannabis sativa, elicits a variety of effects in experimental animals and humans. Delta-9-tetrahydrocannabinol (THC) is the major psychoactive component in marijuana. This substance has been shown, also, to be immunosuppressive and to decrease host resistance to bacterial, protozoan, and viral infections. Macrophages, T lymphocytes, and natural killer cells appear to be major targets of the immunosuppressive effects of THC. Definitive data which directly link marijuana use to increased susceptibility to infection in humans currently is unavailable. However, cumulative reports indicating that THC alters resistance to infection in vitro and in a variety of experimental animals support the hypothesis that a similar effect occurs in humans.     

New sensor developments

The new sensors are the result of new materials, techniques, and calculation and decision capabilities. They are more accurate, reliable, rugged, noncontacting and digital. A microprocessor is integrated with nearly every sensor system, giving both local and milewide access to all information. Many of the new sensors are basic in function — smell, taste, tactile, machine vision, and sound. For example, new odor meters indicate temperature rise as the odorous gas oxidizes or due to an electrode conductivity changes; guidelines are established for quality standards or acceptable odor levels. Or the outputs from several sensors of variables associated with the flavor of liquid are combined in a trial and error relationship until a satisfactory correlation is achieved by artificial intelligence. Thin-film sensors for tactile measurements are based upon electrical conductivity changes with pressure; microprocessor scanning of electrodes results in a quick display of sensitive field-effect transistor pH meter for a drop of sample; chemical environmental sensors; and a micro-gas chromatograph. Fast Fourier Transforms (FFT) applied to a Doppler flowmeter enhance the speed and sensitivity by a factor of ten. Self-calibrating sensors with corrections for either variables include a new radiometer with laser-corrected emissivity and a self-calibrating fiber optic temperature sensor insensitive to emissivity. Infrared photoacoustic sensing is the newest generation of advanced technology sensors for gas analysis, and it results in a most stable zero and span. Other noteworthy new products include hybrid photodetectors, solid-state toxic gas detectors, ultrasonic and microwave radar level and distance gages, microminiature color camera, color scanner, surface quality meter, and multi-wave length spectral analyzers.