Single-photon detection using a quantum dot field effect transistor

A novel device for detection of single photons based on a GaAs/AlGaAs modulation doped field effect transistor (MODFET) which does not rely on avalanche processes is proposed. The optimal channel electron densities and quantum dot parameters for detection of single photons are discussed.

Seismically-induced displacements of a suction caisson in soft clay

The seismic design for offshore foundations is based predominantly on experience onshore. This paper describes the results of dynamic centrifuge tests performed to validate the performance of a suction caisson installed in normally consolidated clay. The main objective is to evaluate the likely plastic displacement under different shaking levels. Permanent displacement results indicate that the displacements experienced are well within the allowable movement for the foundation considered, even though a strength based design approach would consider this to be a failure. Larger earthquakes are seen to produce comparatively smaller displacements. It is concluded that the when designing for seismic loading, if some displacement is permissible then a performance-based approach allowing some displacement proves significantly less conservative than a purely strength-based design. It is also concluded that dynamic response analyses should consider the strength of soil, as this can act as a fuse against large amplitude shear waves. © 2011 Taylor & Francis Group, London.

Reusing steel and aluminum components at end of product life.

Reusing steel and aluminum components would reduce the need for new production, possibly creating significant savings in carbon emissions. Currently, there is no clearly defined set of strategies or barriers to enable assessment of appropriate component reuse; neither is it possible to predict future levels of reuse. This work presents a global assessment of the potential for reusing steel and aluminum components. A combination of top-down and bottom-up analyses is used to allocate the final destinations of current global steel and aluminum production to product types. A substantial catalogue has been compiled for these products characterizing key features of steel and aluminum components including design specifications, requirements in use, and current reuse patterns. To estimate the fraction of end-of-life metal components that could be reused for each product, the catalogue formed the basis of a set of semistructured interviews with industrial experts. The results suggest that approximately 30% of steel and aluminum used in current products could be reused. Barriers against reuse are examined, prompting recommendations for redesign that would facilitate future reuse.