The acoustic phase resonances and surface waves supported by a compound rigid grating (article)

This is the author accepted manuscript. The final version is available from Nature Publishing Group via the DOI in this record.The dataset associated with this article is located in ORE at: https://doi.org/10.24378/exe.606We study the radiative and bound acoustic modes supported by a rigid grating formed of three same-depth, narrow grooves per unit cell. One of the grooves is twice the width of the other two, forming a ‘compound’ grating. The structure supports so-called ‘phase’ resonances where the phase difference of the pressure field between the grooves on resonance varies by multiples of π. We explore the dispersion of these modes experimentally by monitoring the specularly reflected signal as a function of the angle of incidence. In addition, by near-field excitation, the dispersion of the non-radiative surface modes has been characterised. Our results are compared with the predictions of a finite element method model.The authors wish to acknowledge financial support from the Engineering and Physical Sciences Research Council (EPSRC) of the United Kingdom, via the EPSRC Centre for Doctoral Training in Metamaterials (Grant No. EP/L015331/1), QinetiQ and DSTL

Strong beaming of microwave surface waves with complementary split-ring-resonator arrays (article)

This is the final version of the article. Available from Springer Nature via the DOI in this record.The dataset associated with this article is located in ORE at: https://doi.org/10.24378/exe.584A thin copper sheet, populated by an array of complementary split ring resonators, presents strong surface wave beaming in orthogonal directions at two distinct frequencies. This simple array is significantly thinner than existing single frequency beaming surfaces. The observed beaming frequencies are associated with the two lowest resonance modes of the split rings, and the beams are subwavelength in width and approximately non-diverging. The beaming is analysed through comparison of near-field scans of the surface-normal electric fields with numerical simulations.The authors wish to acknowledge financial support from the Engineering and Physical Sciences Research Council (EPSRC) of the United Kingdom, via the EPSRC Centre for Doctoral Training in Metamaterials (Grant No. EP/L015331/1) and also from QinetiQ

Tracing molybdenum attenuation in mining environments using molybdenum stable isotopes

Molybdenum contamination is a concern in mining regions worldwide. Better understanding of processes controlling Mo mobility in mine wastes is critical for assessing potential impacts and developing water-quality management strategies associated to this element. Here, we used Mo stable isotope (δ98/95Mo) analyses to investigate geochemical controls on Mo mobility within a tailings management facility (TMF) featuring oxic and anoxic environments. These isotopic analyses were integrated with X-ray absorption spectroscopy, X-ray diffraction, Raman spectroscopy, transmission electron microscopy, and aqueous chemical data. Dissolved Mo concentrations were inversely correlated with δ98/95Mo values such that enrichment of heavy Mo isotopes in solution reflected attenuation processes. Inner-sphere complexation of Mo(VI) with ferrihydrite was the primary driver of Mo removal and was accompanied by a circa 1 ‰ isotope fractionation. Limited Mo attenuation and isotope fractionation was observed in Fe(II)- and Mo-rich anoxic TMF seepage, while attenuation and isotope fractionation were greatest during discharge and oxidation of this seepage after discharge into a pond where Fe-(oxyhydr)oxide precipitation promoted Mo sorption. Overall, this study highlights the role of sorption onto Fe-(oxyhydr)oxides in attenuating Mo in oxic environments, a process which can be traced by Mo isotope analyses

Thin metamaterial Luneburg lens for surface waves

Copyright © 2013 American Physical SocietyBy suitably patterning a metasurface, the phase velocity of surface waves may be manipulated. Here, a low-loss, thin (1/14th of the free-space wavelength), omnidirectional Luneburg lens, based upon a Sievenpiper “mushroom” array [Sievenpiper et al. IEEE Trans. Microwave Theory Tech. 47 2059 (1999)], is fabricated and characterized at microwave frequencies. Surface waves excited using a near-field point source on the perimeter of the lens, exit the opposite side of the lens as planar wave fronts. The electric field of the surface wave is mapped out experimentally and compared to numerical simulations

The acoustic phase resonances and surface waves supported by a compound rigid grating (dataset)

Included are 3 COMSOL models which were used for the finite element models. Surface-data.zip is the experimental data used to calculate the surface plots. Experimental data dispersion shows the experimental data used for the radiative experiments. Figure.zip contain all figures in .eps, .svg and .pdf format.The article associated with this dataset is located in ORE at: http://hdl.handle.net/10871/33385We study the radiative and bound acoustic modes supported by a rigid grating formed of three same-depth, narrow grooves per unit cell. One of the grooves is twice the width of the other two, forming a 'compound' grating. The structure supports so-called 'phase' resonances where the phase difference of the pressure field between the grooves on resonance varies by multiples of π. We explore the dispersion of these modes experimentally by monitoring the specularly reflected signal as a function of the angle of incidence. In addition, by near-field excitation, the dispersion of the non-radiative surface modes has been characterised. Our results are compared with the predictions of a finite element method model.The authors wish to acknowledge financial support from the Engineering and Physical Sciences Research Council (EPSRC) of the United Kingdom, via the EPSRC Centre for Doctoral Training in Metamaterials (Grant No. EP/L015331/1), QinetiQ and DSTL

Strong beaming of microwave surface waves with complementary split-ring-resonator arrays (dataset)

Raw data from the vector network analyser in the form of amplitude and phase for all frequencies for the whole 2D scan. For each frequency data may be reduced to the form of a 2D plot and this may then be Fourier transformed to give the final figures used in the Young et al. (2018) article "Strong beaming of microwave surface waves with complementary split-ring-resonator arrays" published in Scientific Reports.The article associated with this dataset is located in ORE at: http://hdl.handle.net/10871/33689A thin copper sheet, populated by an array of complementary split ring resonators, presents strong surface wave beaming in orthogonal directions at two distinct frequencies. This simple array is significantly thinner than existing single frequency beaming surfaces. The observed beaming frequencies are associated with the two lowest resonance modes of the split rings, and the beams are subwavelength in width and approximately non-diverging. The beaming is analysed through comparison of near-field scans of the surface-normal electric fields with numerical simulations.The authors wish to acknowledge financial support from the Engineering and Physical Sciences Research Council (EPSRC) of the United Kingdom, via the EPSRC Centre for Doctoral Training in Metamaterials (Grant No. EP/L015331/1) and also from QinetiQ

Design of Visualizations for Urban Modeling

Urban planning experts often use computer models to help evaluate alternative land use policies, particularly as they interact with transportation and environmental decisions. The greatly increased data volume provided by new land use models makes their e#ective use difficult without suitable visualization tools. We present UrbanView, a visualization system for urban modeling, and describe a user study to determine appropriate visualizations for the urban modeling domain