Heterojunction solar cell calculations

Solar cell efficiencies computed for semiconductor heterojunction cell

A position- and time-sensitive photon-counting detector with delay-line read-out

We have developed image intensifier tubes with delay-anode read-out for time- and position-sensitive photon counting. The timing precision is better than 1 ns with 1000x1000 pixels position resolution and up to one megacounts/s processing rate. Large format detectors of 40 and 75 mm active diameter with internal helical-wire delay-line anodes have been produced and specified. A different type of 40 and 25 mm tubes with semi-conducting screen for image charge read-out allow for an economic and robust tube design and for placing the read-out anodes outside the sealed housing. Two types of external delay-line anodes, i.e. pick-up electrodes for the image charge, have been tested. We present tests of the detector and anode performance. Due to the low background this technique is well suited for applications with very low light intensity and especially if a precise time tagging for each photon is required. As an example we present the application of scintillator read-out in time-of-flight (TOF) neutron radiography. Further applications so far are Fluorescence Life-time Microscopy (FLIM) and AstronomyComment: Proceedings of SPIE Conference "Optics and Optoelectronics", 16 - 19. Apr.200

Capping of an Extremely Soft Neutralised Uranium Tailings − A Case History in Environmental Geomechanics

The environmental regulation for Ranger Uranium Mine, in the Northern Territory, Australia, requires the stored tailings (irrespective of where they are finally stored, whether in a tailings dam or in mined-out pits) be capped safely to minimise contamination, erosion and radon gas emission, and also to enable the site to be rehabilitated through revegetation. The hydraulically deposited neutralised tailings in the existing tailings dam have a ‘gel-like’ structure which hinders the consolidation process. Consequently, the in situ tailings have a high water content, low permeability and extremely low shear strength. The present paper describes the case history of a successful capping trial constructed on these extremely soft tailings. Environmental geotechnical issues are highlighted and investigated. Results, especially the characteristics of the tailings observed during the construction and subsequent monitoring, are also discussed

Fossil shark teeth from upland Fleurieu Peninsula, South Australia: evidence for previously unknown Tertiary marine sediments

Neville S Pledge, Anthony R Milnes, Robert P Bourman, and Neville F Alle

Old Jokes, New Media – Online Sexism and Constructions of Gender in Internet Memes

The Internet is a space where the harassment of women and marginalised groups online has attracted the attention of both academic and popular press. Feminist research has found that instances of online sexism and harassment are often reframed as “acceptable” by constructing them as a form of humour. Following this earlier research, this present paper explores a uniquely technologically-bound type of humour by adopting a feminist, social-constructionist approach to examine the content of popular Internet memes. Using thematic analysis on a sample of 240 image macro Internet memes (those featuring an image with a text caption overlaid), we identified two broad, overarching themes – Technological Privilege and Others. Within the analysis presented here, complex and troubling constructions of gendered identity in online humour are explored, illustrating the potential for the othering and exclusion of women through humour in technological spaces. We argue that this new iteration of heteronormative, hegemonic masculinity in online sexism, couched in “irony” and “joking”, serves to police, regulate and create rightful occupants and owners of such spaces

Ruling out the impact of defects on the below band gap photoconductivity of Ti supersaturated Si

In this study, we present a structural and optoelectronic characterization of high dose Ti implanted Si subsequently pulsed-laser melted (Ti supersaturated Si). Time-of-flight secondary ion mass spectrometry analysis reveals that the theoretical Mott limit has been surpassed after the laser process and transmission electron microscopy images show a good lattice reconstruction. Optical characterization shows strong sub-band gap absorption related to the high Ti concentration. Photoconductivity measurements show that Ti supersaturated Si presents spectral response orders of magnitude higher than unimplanted Si at energies below the band gap. We conclude that the observed below band gap photoconductivity cannot be attributed to structural defects produced by the fabrication processes and suggest that both absorption coefficient of the new material and lifetime of photoexcited carriers have been enhanced due to the presence of a high Ti concentration. This remarkable result proves that Ti supersaturated Si is a promising material for both infrared detectors and high efficiency photovoltaic devices

Modelling Discharge Rates and Ground Settlement Induced by Tunnel Excavation

Interception of aquifers by tunnel excavation results in water inflow and leads to drawdown of the water table which may induce ground settlement. In this work, analytical and numerical models are presented which specifically address these groundwater related processes in tunnel excavation. These developed models are compared and their performance as predictive tools is evaluated. Firstly, the water inflow in deep tunnels is treated. It is shown that introducing a reduction factor accounting for the effect of effective stress on hydrodynamic parameters avoids overestimation. This effect can be considered in numerical models using effective stress-dependent parameters. Then, quantification of ground settlement is addressed by a transient analytical solution. These solutions are then successfully applied to the data obtained during the excavation of the La Praz exploratory tunnel in the Western Alps (France), validating their usefulness as predictive tools