Performance of a V-trough photovoltaic/thermal concentrator

The idea of concentrating solar energy to increase the output of photovoltaic and solar thermal collectors is an area that has received significant attention. In this study, a design model for a V-trough concentrating photovoltaic/thermal solar collector was theoretically analysed and validated with experimental data. The results showed that the V-trough offered improved electrical yields from both concentrating radiation onto the photovoltaic cells and also by actively cooling them. Also, it was shown that the V-trough could be made of a durable (long life) stainless steel, rather than the more reflective aluminium, while still offering a 25% increase in incident radiation over a typical year. However it was noted that modifications would be needed to improve cooling and to increase the thermal efficiency by reducing heat losses

Staff perceptions of higher education science and engineering learning communities

This paper presents staff perceptions of higher education science and engineering learning communities derived from a cross-case analysis of four case studies across the New Zealand university and polytechnic sectors. First we report staff expectations and experiences in terms of infrastructure and resources, and their own careers. Staff perceptions of the diversity and differences in learning styles of their students are next, followed by the importance of practical skill development, pedagogies employed and their rationale, along with scaffolding and supporting of learning. The paper concludes by considering the nature of science (NoS) and engineering, and what messages about the NoS are presented by higher education staff. The research findings suggest that staff face conflicting demands on their time, with requirements for research and administration affecting their teaching roles. Lecturers report considerable diversity and students often ill-prepared for higher education study, and consider that students are required to learn a huge amount of information. While some staff attended courses in teaching, they feel unable to apply their learning in order to enhance student learning because of concerns that time spent doing so would reduce the amount of time available to deliver content. Class sizes were identified as having considerable impact on student learning and lectures offer little opportunity for active student engagement. Practical classes are highly valued, being seen as crucial for learning practical techniques and problem-solving. Small classes and practical classes provide opportunities to develop good working relationships with students. Lecturers felt that students need to become more independent and self-reliant in their learning, and that they needed to be supported in this process at the institutional level

Oscillator strengths of neutral and singly ionised molybdenum

Oscillator strengths of 174 Mo(I) and 58 Mo(II) lines in the range 2470–5570 Å were obtained from wall-stabilised arc and hollow cathode measurements. Sets of relative f-values were determined by a combination of hook and emission measurements requiring no assumptions concerning the plasma state. The sets have been enlarged considerably by evaluating spectra recorded with a Fourier spectrometer. The relative Mo(I) f-values were converted to an absolute scale by means of radiative lifetimes measured by P. Zimmermann and his group. The overall uncertainties are within 10–35%. Since lifetimes of Mo(II) levels are not yet available, only relative Mo(II) f-values are presented