Pressure-driven flow of solid helium

The recent torsional oscillator results of Kim and Chan suggest a supersolid phase transition in solid 4He. We have used a piezoelectrically driven diaphragm to study the flow of solid helium through an array of capillaries. Our measurements showed no indication of low temperature flow, placing stringent restrictions on supersolid flow in response to a pressure difference. The average flow speed at low temperatures was less than 1.2x10-14 m/s, corresponding to a supersolid velocity at least 7 orders of magnitude smaller than the critical velocities inferred from the torsional oscillator measurements.Comment: 4 pages, 3 figure

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

Development of a Pre-Driven Recovery Evaluation Program for Longwall Operations

Many longwall coordinators are examining the use of pre-driven recovery roadways. This method, if performed successfully can improve the overall efficiency and safety of moving longwall equipment from panel to panel. However, it is difficult to assess the feasibility of using predriven recovery unless extensive research is carried out or a consultant is used to analyse the particular situation. A number of previous case studies have been analysed to discover which parameters have the greatest influence on the success of pre-driven recovery. Floor strength, Coal Mine Roof Rating (CMRR), extraction depth, Roof Density Index (RDI), standing support and mining rate were the main parameters impacting on the successful implementation of pre-driven recovery roadways. These parameters have been incorporated into a program that was developed to assess the feasibility of using pre-driven recovery roadways. The Pre-driven Recovery Evaluation Program (PREP) is simple to operate and it will enable new longwall mining operations as well as current operations to quickly determine the suitability of the method to their site

Deformation of Silica Aerogel During Fluid Adsorption

Aerogels are very compliant materials - even small stresses can lead to large deformations. In this paper we present measurements of the linear deformation of high porosity aerogels during adsorption of low surface tension fluids, performed using a Linear Variable Differential Transformer (LVDT). We show that the degree of deformation of the aerogel during capillary condensation scales with the surface tension, and extract the bulk modulus of the gel from the data. Furthermore we suggest limits on safe temperatures for filling and emptying low density aerogels with helium.Comment: 8 pages, 5 figures, submitted to PR

What Matters Most When Students and Teachers Use Interactive Whiteboards in Mathematics Classrooms?

As teachers, we are encouraged to immerse our students in rich and engaging learning environments (NSW Department of Education and Training, 2003). One teaching tool that can facilitate the creation of rich learning environments is the interactive whiteboard (IWB) (Baker, 2009). IWBs are quickly being introduced into schools across the nation and worldwide, and educators are exploring the implications of having them in the classroom. Of particular interest are student attitudes to the use of IWBs: what students think and feel about IWBs, and what factors matter most to students when IWBs are used in their classroom. Attitudes play an important part in student interest and engagement levels, therefore, it is important to determine current student attitudes towards IWB use in the classroom

Bumpy Moments and Joyful Breakthroughs: The Place of Threshold Concepts in Academic Staff Development Programs About Online Learning and Teaching

In this article the authors address the situation in higher education of academic staff facing what they conceptualise as “bumpy moments and joyful breakthroughs” as they work through the process of becoming teachers in online learning environments. The article comes from a research project, which gathered and analysed data from systematic observations and questionnaires. The authors base their study on the known fact that while many academics have grounded experience in on-campus teaching and learning situations they do not necessarily have the skills required today for extending learning through on-line environments. The authors discover that when academics start teaching in online environments, or at least start facing the fact that there are requirements to do so, and they begin to explore this environment both personally and theoretically, “they encounter threshold concepts that can unsettle their most deeply held personal and pedagogical beliefs about what it means to teach and learn, and what it means to be an effective teacher and learner”. This paper gives an account of the research into these new conditions for educators and offers a set of recommendations “to inform the design of a multi-strategy academic staff learning program, which facilitated the development of online teaching skills”. [From Introduction to issue of ACCESS]

Commissioning adiabatic oven testing - an inter-laboratory comparison

Adiabatic oven testing for spontaneous combustion assessment has been a primary method used by the Australian and New Zealand coal industries for input to the development of Principal Hazard Management Plans for mining operations. Consistency of results is important to ensure that the ratings obtained are accurate and reliable for maintaining the integrity of the database used to compare between mines and for obtaining site specific relationships. This paper presents the results from commissioning tests of four new adiabatic ovens at two different laboratories, which show the high level of reproducibility and repeatability needed for confidence in planning of future mining operations. The results cover a range of coal self-heating rates to show the validity of the testing and the reliability of the adiabatic ovens