Measurement of model aeroelastic deformations in the wind tunnel at transonic speeds using stereophotogrammetry

A stereophotographic method of determining the aeroelastic deformations of an airplane model under aerodynamic load in the wind tunnel was evaluated. Wind tunnel tests were conducted in the Langley 8 foot transonic pressure tunnel on the wing of a 0.0625 scale model of the TF-8A supercritical wing research airplane to obtain simultaneously the aerodynamic forces and moments, pressure distributions, and stereophotographs. Tests were conducted at Mach numbers of 0.80, 0.95, and 1.20, and at free stream dynamic pressures of 20,349 Pa and 40,698 Pa. Accuracy of the stereophotographic technique in determining wing deflections was within 0.013 cm under static conditions. This value translates to an error in wing twist of 0.10 deg inboard and increases to 0.20 deg outboard. When the model was under aerodynamic load in the wind tunnel, the accuracy of the stereophotographic technique of determining wind deflections increased to 0.052 cm when compared with static wing loadings because of the dynamic motion of the model in the tunnel

UNICEF IWASH Project, Northern Region, Ghana : an adapted training manual for groundwater development

This report is an adapted training manual, with specific best practice recommendations for groundwater development practitioners working in the Northern Region, Ghana. It is designed to be used in conjunction with the existing comprehensive training manual ‘Developing Groundwater: a guide to rural water supply’ by MacDonald, Davies, Calow and Chilton (2005). The additional guidelines provided in this supplementary report are specific to the Northern Region of Ghana, and have been informed by a review of groundwater development in the region which BGS carried out on behalf of UNICEF in 2010-2011. The Northern Region is a difficult area in which to find and develop groundwater resources. For this reason, more resources – time and money – need to be focussed on careful borehole siting and development in order to maximise success. This includes detailed desk and field reconnaissance surveys; the effective use and interpretation of geophysical siting methods; collection of good quality data during drilling and test pumping; rigorous recording and management of data; and effective interpretation, sharing and use of hydrogeological information by all groundwater development practitioners. This report, and the associated manual ‘Developing Groundwater’, provide practical help for carrying out these activities effectively. The authors gratefully acknowledge those persons who contributed to the formation of these guidelines, who include: UNICEF Ghana – Othniel Habila, Kabuka Banda and David Ede Community Water and Sanitation Agency (CWSA), Ghana – John Aduakye Canadian International Development Agency (CIDA) – Hydrogeological Assessment Project (HAP) – James Racicot All participants at the UNICEF/BGS workshop and training programme held in Tamale, Northern Region, from 7 to 18 February 2011

Low frequency elastic measurements on solid 4^{4}He in Vycor using a torsional oscillator

Torsional oscillator experiments involving solid $^{4}$He confined in the nanoscale pores of Vycor glass showed anomalous frequency changes at temperatures below 200 mK. These were initially attributed to decoupling of some of the helium's mass from the oscillator, the expected signature of a supersolid. However, these and similar anomalous effects seen with bulk $^{4}$He now appear to be artifacts arising from large shear modulus changes when mobile dislocations are pinned by $^{3}$He impurities. We have used a torsional oscillator (TO) technique to directly measure the shear modulus of the solid $^{4}$He/Vycor system at a frequency (1.2 kHz) comparable to that used in previous TO experiments. The shear modulus increases gradually as the TO is cooled from 1 K to 20 mK. We attribute the gradual modulus change to the freezing out of thermally activated relaxation processes in the solid helium. The absence of rapid changes below 200 mK is expected since mobile dislocations could not exist in pores as small as those of Vycor. Our results support the interpretation of a recent torsional oscillator experiment that showed no anomaly when elastic effects in bulk helium were eliminated by ensuring that there were no gaps around the Vycor sample.Comment: Accepted by Journal of Low Temperature Physic

Critical Habitat and the Conservation Ecology of the Freshwater Parasitic Lamprey, Lampetra macrostoma

Lampetra macrostoma, the Cowichan Lamprey, is a freshwater parasitic lamprey that probably evolved from L. tridentata within the last 10 000 years. It is unique to the Cowichan Lake watershed on Vancouver Island, British Columbia, Canada. Larval rearing in Mesachie and Cowichan lakes occurs in shallow, silt-covered gravel areas at the mouths of rivers and streams flowing into the lakes. Spawning occurs over a protracted period from early May until about late July. Shallow areas with small gravel along the shore of the lakes, near the mouths of rivers are essential for successful spawning. Adults prey on a variety of salmonid species within the lake. There has been considerable development around Mesachie Lake and reported increased fishing pressure on prey in Mesachie and Cowichan lakes. It is not known if the size of the population of L. macrostoma has changed since an initial study in the early 1980s, but a study in 2008 captured very few spawning lamprey in Mesachie Lake, possibly indicating that the population is declining

Dislocation networks in helium-4 crystals

The mechanical behavior of crystals is dominated by dislocation networks, their structure and their interactions with impurities or thermal phonons. However, in classical crystals, networks are usually random with impurities often forming non-equilibrium clusters when their motion freezes at low temperature. Helium provides unique advantages for the study of dislocations: crystals are free of all but isotopic impurities, the concentration of these can be reduced to the ppb level, and the impurities are mobile at all temperatures and therefore remain in equilibrium with the dislocations. We have achieved a comprehensive study of the mechanical response of 4He crystals to a driving strain as a function of temperature, frequency and strain amplitude. The quality of our fits to the complete set of data strongly supports our assumption of string-like vibrating dislocations. It leads to a precise determination of the distribution of dislocation network lengths and to detailed information about the interaction between dislocations and both thermal phonons and 3He impurities. The width of the dissipation peak associated with impurity binding is larger than predicted by a simple Debye model, and much of this broadening is due to the distribution of network lengths.Comment: accepted by Phys. Rev.

A temperature-controlled device for volumetric measurements of Helium adsorption in porous media

We describe a set-up for studying adsorption of helium in silica aerogels, where the adsorbed amount is easily and precisely controlled by varying the temperature of a gas reservoir between 80 K and 180 K. We present validation experiments and a first application to aerogels. This device is well adapted to study hysteresis, relaxation, and metastable states in the adsorption and desorption of fluids in porous media

Ground-truthing airborne EM - Hydrochemical characterization of a coal mine plume

A trial airborne EM (AEM) survey was carried out across a 13 x 9 km area of the northern Nottinghamshire (UK) coalfield. One of the objectives was to examine the influence of collieries situated above the Triassic Sherwood Sandstone aquifer. The conductivity models obtained from the AEM survey revealed extensive zones of enhanced subsurface conductivity in the vicinity of all the collieries in the survey area. The purpose of the present study is to provide information regarding subsequent investigations (ground geophysics and borehole) to confirm the AEM results and to investigate the geochemical nature of the conductive zone identified in the vicinity of one of the collieries

Helium condensation in aerogel: avalanches and disorder-induced phase transition

We present a detailed numerical study of the elementary condensation events (avalanches) associated to the adsorption of $^4$He in silica aerogels. We use a coarse-grained lattice-gas description and determine the nonequilibrium behavior of the adsorbed gas within a local mean-field analysis, neglecting thermal fluctuations and activated processes. We investigate the statistical properties of the avalanches, such as their number, size and shape along the adsorption isotherms as a function of gel porosity, temperature, and chemical potential. Our calculations predict the existence of a line of critical points in the temperature-porosity diagram where the avalanche size distribution displays a power-law behavior and the adsorption isotherms have a universal scaling form. The estimated critical exponents seem compatible with those of the field-driven Random Field Ising Model at zero temperature.Comment: 16 pages, 14 figure

An evaluation of combined geophysical and geotechnical methods to characterize beach thickness

Beaches provide sediment stores and have an important role in the development of the coastline in response to climate change. Quantification of beach thickness and volume is required to assess coastal sediment transport budgets. Therefore, portable, rapid, non-invasive techniques are required to evaluate thickness where environmental sensitivities exclude invasive methods. Site methods and data are described for a toolbox of electrical, electromagnetic, seismic and mechanical based techniques that were evaluated at a coastal site at Easington, Yorkshire. Geophysical and geotechnical properties are shown to be dependent upon moisture content, porosity and lithology of the beach and the morphology of the beach–platform interface. Thickness interpretation, using an inexpensive geographic information system to integrate data, allowed these controls and relationships to be understood. Guidelines for efficient site practices, based upon this case history including procedures and techniques, are presented using a systematic approach. Field results indicated that a mixed sand and gravel beach is highly variable and cannot be represented in models as a homogeneous layer of variable thickness overlying a bedrock half-space