Variation in the thickness of a fluid interface due to internal wave propagation:a lattice Boltzmann simulation

The change in the thickness of an interface between two immiscible fluids due to the propagation of an internal capillary-gravity wave along the interface is considered using a Bhatnagar, Gross and Krook (BGK) lattice Boltzmann model of a binary of fluid. The vertical thickness of the interface is recorded from the simulations since this is the most easily measured quantities in any simulation or experiment. The vertical thickness is then related to the actual thickness (perpendicular to the interface) which is seen to vary with the phase of the wave. The positions of the maxima and minimum thicknesses are seen to be approximately constant relative to the phase of the propagating wave and the range of variation of the thickness decreases at approximately the same rate as the wave amplitude is damped. A simplified model for the interface is considered which predicts a similar variation due to the interface being stretched as the internal wave propagates

The effects on memory and self-reported behaviour of four types of information about water conservation

Education campaigns conducted by water management agencies are intended to motivate people to conserve water. However, there has been little research to determine what kind of information best achieves this goal. Four types of information partly based on Stem, Dietz and Kalof\u27s (1993) social-psychological model of environmental value orientations were examined in this study: action information about ways to conserve water; abstract factual information about water and its use; anthropocentric information about how people are affected by water use; and ecocentric information about how the environment is affected by water use. Using cluster sampling techniques 160 participants were selected from four Perth suburbs (two upper-middle income suburbs, and two lower-middle income suburbs). Brochures containing the four different types of information (all including action information) were randomly distributed to participants who were then asked to rate the perceived importance of each information item. Three weeks after distribution participants were assessed on their memory of the information, and on their self-reported water conservation behaviours. There was an interaction of information with income on importance ratings, with the lower-middle income group rating ecocentric information as relatively important, while the upper-middle income group rated it as relatively unimportant. There was a main effect for memory, with post hoc tests indicating that abstract information was remembered significantly better than anthropocentric information. In addition to having higher memory scores, people receiving abstract information reported the most behaviour change. However, post hoc tests revealed that this was significantly different only from ecocentric information, for which people reported the least behaviour change. The relative effectiveness of the abstract information may be explained by the simple and novel nature of many of the items. The failure of ecocentric information to lead to behaviour change appears inconsistent with previous findings that suggest environmental concern motivates conservation behaviour. This failure was not surprising in the upper middle income group which found the information relatively unimportant. For people in the lower-middle income group it is possible that a) they feel helpless in the face of environmental problems, or b) their perceived importance ratings were based on symbolic attitudes which have little influence on behaviour when self-interests also prevail

The Effectiveness of an Integrated Oral Language-Writing Program, Using Grouping, on the Composing Ability and Writing Attitudes of Ninth Grade Students

The purpose of this study was to investigate the effect of an integrated oral language-writing program, using grouping, on ability to compose and on writing attitude. A secondary purpose was to see if there were a relationship between ability to compose and writing attitude. A pretest, posttest design with a control group was used for the study. The treatment group consisted of twenty-seven students from a heterogeneously grouped rural-suburban school. The control group consisted of twenty-seven students, heterogeneously grouped, from a suburban-rural school. Students in the treatment group were divided into groups of three, meeting twice a week, for a nine week period for the purpose of discussion and writing. A communication spiral, involving students in the three stages of the process of writing, was used as a guide. Researcher-devised writing-oral language activities were used. The control group received no treatment, but rather, writing activities consisted of being assigned a topic to write on or writing an essay based on a story or play they had read in literature. Students in both groups were administered the Writing Apprehension Scale devised by Daly and Miller (1975) before and after the nine week treatment program. A writing sample was taken before and after the nine week treatment period. After establishing group equivalency, t tests for small independent samples were used to determine if there were a significant difference in composing ability and writing attitude between the treatment and control group after the treatment program. In order to determine if there were significant gains from pretest to posttest for both groups in writing attitude and composing ability, t tests for dependent samples were used. Correlation coefficients were obtained to see if there were a significant relationship between ability to compose and writing attitude. The results indicated that there was a significant improvement in attitude toward writing for the students in the integrated oral language-writing program. There was also a significant gain in composing ability from pretest to posttest for students in the treatment program. The correlation study failed to find a significant relationship between writing attitude and composing ability. Recommendations for classroom application as well as suggestions for future research were given

Thermal-distortion analysis of a spacecraft box truss in geostationary orbit

The Mission to Planet Earth enlists the use of a geostationary platform to support Earth science monitoring instruments. The strongback for a proposed geostationary platform is a deployable box truss that supports two large diameter passive microwave radiometer (PMR) and several other science instruments. A study was performed to estimate the north-south and east-west pointing errors at the mounting locations of the two PMRs due to on-orbit thermal distortions of the main truss. The baseline configuration indicated that the east-west pointing error greatly exceeded the required limits. Primary origins of the pointing errors were identified, and methods for their reduction were discussed. Thermal performance enhancements to the truss structure were modeled and analyzed, including state-of-the-art surface coatings and insulation techniques. Comparisons of the thermal enhancements to the baseline were performed. Results demonstrated that using a thermal enclosure insulating technique reduced external heat fluxes, and distributed those heat fluxes more evenly throughout the structure, sufficiently reducing the pointing error to satisfy pointing accuracy requirements for the PMR's

Characterisation of the transmissivity field of a fractured and karstic aquifer, Southern France

International audienceGeological and hydrological data collected at the Terrieu experimental site north of Montpellier, in a confined carbonate aquifer indicates that both fracture clusters and a major bedding plane form the main flow paths of this highly heterogeneous karst aquifer. However, characterising the geometry and spatial location of the main flow channels and estimating their flow properties remain difficult. These challenges can be addressed by solving an inverse problem using the available hydraulic head data recorded during a set of interference pumping tests.We first constructed a 2D equivalent porous medium model to represent the test site domain and then employed regular zoning parameterisation, on which the inverse modelling was performed. Because we aim to resolve the fine-scale characteristics of the transmissivity field, the problem undertaken is essentially a large-scale inverse model, i.e. the dimension of the unknown parameters is high. In order to deal with the high computational demands in such a large-scale inverse problem, a gradient-based, non-linear algorithm (SNOPT) was used to estimate the transmissivity field on the experimental site scale through the inversion of steady-state, hydraulic head measurements recorded at 22 boreholes during 8 sequential cross-hole pumping tests. We used the data from outcrops, borehole fracture measurements and interpretations of inter-well connectivities from interference test responses as initial models to trigger the inversion. Constraints for hydraulic conductivities, based on analytical interpretations of pumping tests, were also added to the inversion models. In addition, the efficiency of the adopted inverse algorithm enables us to increase dramatically the number of unknown parameters to investigate the influence of elementary discretisation on the reconstruction of the transmissivity fields in both synthetic and field studies.By following the above approach, transmissivity fields that produce similar hydrodynamic behaviours to the real head measurements were obtained. The inverted transmissivity fields show complex, spatial heterogeneities with highly conductive channels embedded in a low transmissivity matrix region. The spatial trend of the main flow channels is in a good agreement with that of the main fracture sets mapped on outcrops in the vicinity of the Terrieu site suggesting that the hydraulic anisotropy is consistent with the structural anisotropy. These results from the inverse modelling enable the main flow paths to be located and their hydrodynamic properties to be estimated