Comprehensive Property Retrieval and Measurement of Concrete Spalling Using Machine Vision for Post-Earthquake Safety Assessments

Active vibration control (AVC) is a relatively new technology for the mitigation of annoying human-induced vibrations in floors. However, recent technological developments have demonstrated its great potential application in this field. Despite this, when a floor is found to have problematic floor vibrations after construction the unfamiliar technology of AVC is usually avoided in favour of more common techniques, such as Tuned Mass Dampers (TMDs) which have a proven track record of successful application, particularly for footbridges and staircases. This study aims to investigate the advantages and disadvantages that AVC has, when compared with TMDs, for the application of mitigation of pedestrian-induced floor vibrations in offices. Simulations are performed using the results from a finite element model of a typical office layout that has a high vibration response level. The vibration problems on this floor are then alleviated through the use of both AVC and TMDs and the results of each mitigation configuration compared. The results of this study will enable a more informed decision to be made by building owners and structural engineers regarding suitable technologies for reducing floor vibrations.

On the photoluminescence of a-C:H films

a-C:H films deposited from methane and helium mixture in a capacitively coupled rf plasma were found to show photoluminescence (PL) with peak intensities at energies far above the Taue gap of these films. Apart from the PL the films were investigated with respect to their IR and UV/VIS absorption properties as well as their Raman spectra were examined. The ultraviolet (UV) and blue luminescence from hard a-C:H thin films are explained by incorporation of polycyclic hydrocarbons from gas-phase reactions in the methane helium plasma into the film.

Subbandgap photoluminescence of Si photonic crystal nanocavity at room temperature

Using a photonic crystal cavity and a hydrogen plasma treatment, we enhance the photoluminescence (PL) from optically active defects in silicon by a factor of 3000 compared to the as-bought material at room temperature. © 2011 IEEE.

Spatially-resolved photoluminescence imaging of CdS and GaAs/AlGaAs nanowires

We use low temperature spatially resolved photoluminescence imaging to study optical properties and electronic states of single CdS and GaAs/AlGaAs core-shell nanowires. © 2007 American Institute of Physics.

Polarization and temperature dependence of photoluminescence from zincblende and wurtzite InP nanowires

We use polarization-resolved and temperature-dependent photoluminescence of single zincblende (ZB) (cubic) and wurtzite (WZ) (hexagonal) InP nanowires to probe differences in selection rules and bandgaps between these two semiconductor nanostructures. The WZ nanowires exhibit a bandgap 80 meV higher in energy than the ZB nanowires. The temperature dependence of the PL is similar but not identical for the WZ and ZB nanowires. We find that ZB nanowires exhibit strong polarization parallel to the nanowire axis, while the WZ nanowires exhibit polarized emission perpendicular to the nanowire axis. This behavior is interpreted in terms of the different selection rules for WZ and ZB crystal structures. © 2007 American Institute of Physics.

Temperature dependence of photoluminescence from single core-shell GaAs-AlGaAs nanowires

Temperature-dependent polarized microphotoluminescence measurements of single GaAsAlGaAs core-shell nanowires are used to probe their electronic states. The low-temperature emission from these wires is strongly enhanced compared with that observed in bare GaAs nanowires and is strongly polarized, reflecting the dielectric mismatch between the nanowire and the surrounding air. The temperature-dependent band gap of the nanowires is seen to be somewhat different from that observed in bulk GaAs, and the PL rapidly quenches above 120 K, with an activation energy of 17 meV reflecting the presence of nonradiative defects. © 2006 American Institute of Physics.