191 research outputs found
Are Euclidean Distance and Network Distance Related ?
Although spatial distance is a very important concept for a wide variety of disciplines including social, natural, and information sciences, the methods used to measure spatial distance are not directly expressed and fully explained. In this study, we calculate and compare Euclidean distances and network distances for 10 randomly selected European cities. On the contrary to the findings reported in past research, we find that there is not a global straight forward relation between the Euclidian distance and network distance.© 2016. The Authors. Published for AMER ABRA by e-International Publishing House, Ltd., UK. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).Peer–review under responsibility of AMER (Association of Malaysian Environment-Behaviour Researchers), ABRA (Association of Behavioural Researchers on Asians) and cE-Bs (Centre for Environment-Behaviour Studies), Faculty of Architecture, Planning & Surveying, Universiti Teknologi MARA, Malaysia.Keywords: Euclidean distance; network distance; network analysi
Examination of the Relationship between Urban Air Pollution and Urban Planning Decisions in Cigli Case, Izmir (Turkey)
The air pollution problem remains, although significant improvements have been seen in urban air quality over the last years. Despite the size and variety of studies on urban air pollution, the usage of spatial statistics has been extremely limited. This study aims to show that the spatial statistic techniques can well be used to examine and explain the air pollution levels in urban areas. The data for the sulphur dioxide (SO2) and nitrogen dioxide (NO2) concentrations are measures using passive diffusion tubes at the 67 monitoring sites in the district of Çiğli (Izmir), which are selected through a spatial systematic sampling process. The tubes were exposed for a 2-week period in August 2015. For the determination of the level of clustering for high values and low values of SO2 and NO2 concentrations, Getis-Ord G* local statistics are calculated. There are five points with high values of SO2 surrounded by low values, three points of NO2, where the results are statistically significant at the 0.10 level. The findings indicate that the presence of the industrial zone, the form of fossil fuels (coal or natural gas) used in heating, and topography are the strong determinants urban air pollution.© 2016. The Authors. Published for AMER ABRA by e-International Publishing House, Ltd., UK. Peer–review under responsibility of AMER (Association of Malaysian Environment-Behaviour Researchers), ABRA (Association of Behavioural Researchers on Asians) and cE-Bs (Centre for Environment-Behaviour Studies), Faculty of Architecture, Planning & Surveying, Universiti Teknologi MARA, Malaysia.Keywords: Urban air pollution; planning decisions; spatial autocorrelation; air pollutant
Transmission and Reflection Properties of Composite Double Negative Metamaterials in Free Space
Cataloged from PDF version of article.We report free space transmission and the first reflection
measurements of a composite double negative (DNG) metamaterial,
also known as a left-handed material (LHM). The metamaterial
composes of the split-ring-resonators and discontinuous
thin wires. Very high transmission values of the metamaterial are
observed within a frequency range for which both effective permeability
and permittivity are expected to be negative
The influence of phosphorus content on magnetic anisotropy in ferromagnetic (Ga, Mn) (As, P)/GaAs thin films
International audienceThe magnetic anisotropy of the ferromagnetic semiconductor (Ga, Mn) (As, P) is studied in a material-specific microscopic k . p approach. We calculate the electronic energy band structure of (Ga, Mn) (As, P) quaternary ferromagnetic alloys using a 40-band k . p model and taking into account the s, p-d exchange interaction and the strain of the (Ga, Mn) (As, P) layer on a GaAs substrate. We determine the variations of the carrier effective masses in the strained (Ga, Mn) (As, P)/GaAs system. The magnetic anisotropy constants obtained from our simulations using a mean-field model are compared with the experimental ones determined by ferromagnetic resonance spectroscopy on a set of samples with constant manganese concentration and varying phosphorus concentration. An excellent quantitative agreement between experiment and theory is found for the uniaxial out-of-plane and cubic in-plane anisotropy parameters
Refraction and rightness in photonic crystals
We present a study on relation between the refraction and rightness effects
in photonic crystals applied on a 2D square lattice photonic crystal. The plane
wave (the band and equifrequency contour analyses) and FDTD calculations for
both TM and TE modes revealed all possible refraction and rightness cases in
photonic crystal structures in the first three bands. In particular, we show
for the first time, a possibility of the left-handed positive refraction. This
means that left-handedness does not necessarily imply negative refraction in
photonic crystals.Comment: 10 pages, 13 figures, pd
Negative Refraction and Left-handed electromagnetism in Microwave Photonic Crystals
We demonstrate negative refraction of microwaves in metallic photonic
crystals. The spectral response of the photonic crystal, which manifests both
positive and negative refraction, is in complete agreement with band-structure
calculations and numerical simulations. The negative refraction observed
corresponds to left-handed electromagnetism and arises due to the dispersion
characteristics of waves in a periodic medium. This mechanism for negative
refraction is different from that in metamaterials.Comment: 13 pages, 4 figure
The Relationship between Urban Air Pollution and Urban Planning Decisions
The air pollution problem remains, although significant improvements have been seen in urban air quality over the last years. This study aims to show that the spatial statistic techniques can well be used to examine and explain the air pollution levels in urban areas. The data for SO2 and NO2 concentrations are measures using passive diffusion tubes at the 67 monitoring sites in the district of Çiğli (Izmir). The tubes were exposed for a 2-week period in August 2015. For the determination of the level of clustering for high values and low values of pollutants, Getis-Ord G* local statistics are calculated. There are five points with high values of SO2 surrounded by low values, three points of NO2, where the results are statistically significant at the 0.10 level. The presence of the industrial zone, the form of fossil fuels used in heating, and topography are strong determinants urban air pollution.Keywords: Urban air pollution, planning decisions, spatial autocorrelation, air pollutants eISSN 2398-4279 © 2018. The Authors. Published for AMER ABRA cE-Bs by e-International Publishing House, Ltd., UK. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer–review under responsibility of AMER (Association of Malaysian Environment-Behaviour Researchers), ABRA (Association of Behavioural Researchers on Asians) and cE-Bs (Centre for Environment-Behaviour Studies), Faculty of Architecture, Planning & Surveying, Universiti Teknologi MARA, Malaysia. https://doi.org/10.21834/ajqol.v3i11.134
Transmission and reflection properties of composite metamaterials in free space
We measured transmission and reflection from SRRs, thin wires, and composite metamaterials in free space. X-band measurement exhibits high transmission magnitude for frequencies where both SRR and wire have effective negative permeability and permittivity, respectively. © 2000 Optical Society of America
Subwavelength resolution in a two-dimensional photonic-crystal-based superlens
The experimental and theoretical demonstration of a single-beam negative refraction and a superlensing effect in 2D photonic crystals was reported. As such, negative refraction was observed for the incidence angles of >20°. This broad angle range was used to demonstrate the superlensing effect, where the electromagnetic waves emitted from a point source were focused on the other side of the PC
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