2,449 research outputs found
Temporal evolution of mesoscopic structure of some non-Euclidean systems using a Monte Carlo model
A Monte Carlo based computer model is presented to comprehend the contrasting
observations of Mazumder et al. [Phys. Rev. Lett. 93, 255704 (2004) and Phys.
Rev. B 72, 224208 (2005)], based on neutron-scattering measurements, on
temporal evolution of effective fractal dimension and characteristic length for
hydration of cement with light and heavy water. In this context, a theoretical
model is also proposed to elucidate the same.Comment: 31 Pages, 13 Figure
Directional acoustic measurements by laser Doppler velocimeters
Laser Doppler velocimeters (LDVs) were used as velocity microphones to measure sound pressure level in the range of 90-130 db, spectral components, and two-point cross correlation functions for acoustic noise source identification. Close agreement between LDV and microphone data is observed. It was concluded that directional sensitivity and the ability to measure remotely make LDVs useful tools for acoustic measurement where placement of any physical probe is difficult or undesirable, as in the diagnosis of jet aircraft noise
Regional Disparity of Covid-19 Infections: An Investigation using State Level Indian Data
Using the state level panel data for India, we establish that Covid infections are clustered in more urbanized, and prosperous states. Poverty lowers cases showing evidence of herd immunity of poor which stands in sharp contrast with the developed part of the world. Our dynamic panel regression results indicate that Covid infections are persistent across states and unlocking has aggravated the infections. We also find that richer and more urbanised states with better health infrastructure and governance perform more tests. The policy lesson from this exercise is that the authorities should monitor immunization and Covid protocols in densely populated urban areas
Spectroscopic diagnostics of plasma during laser processing of aluminium
The role of the plasma in laser–metal interaction is of considerable interest due to its influence in the energy transfer mechanism in industrial laser materials processing. A 10 kW CO2 laser was used to study its interaction with aluminium under an argon environment. The objective was to determine the absorption and refraction of the laser beam through the plasma during the processing of aluminium. Laser processing of aluminium is becoming an important topic for many industries, including the automobile industry. The spectroscopic relative line to continuum method was used to determine the electron temperature distribution within the plasma by investigating the 4158 ° Ar I line emission and the continuum adjacent to it. The plasmas are induced in 1.0 atm pure Ar environment over a translating Al target, using f/7 and 10 kW CO2 laser. Spectroscopic data indicated that the plasma composition and behaviour were Ar-dominated. Experimental results indicated the plasma core temperature to be 14 000–15 300 K over the incident range of laser powers investigated from 5 to 7 kW. It was found that 7.5–29% of the incident laser power was absorbed by the plasma. Cross-section analysis of the melt pools from the Al samples revealed the absence of any key-hole formation and confirmed that the energy transfer mechanism in the targets was conduction dominated for the reported range of experimental data.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/58114/2/d7_19_021.pd
Ferromagnetism in nanoscale BiFeO3
A remarkably high saturation magnetization of ~0.4mu_B/Fe along with room
temperature ferromagnetic hysteresis loop has been observed in nanoscale (4-40
nm) multiferroic BiFeO_3 which in bulk form exhibits weak magnetization
(~0.02mu_B/Fe) and an antiferromagnetic order. The magnetic hysteresis loops,
however, exhibit exchange bias as well as vertical asymmetry which could be
because of spin pinning at the boundaries between ferromagnetic and
antiferromagnetic domains. Interestingly, like in bulk BiFeO_3, both the
calorimetric and dielectric permittivity data in nanoscale BiFeO_3 exhibit
characteristic features at the magnetic transition point. These features
establish formation of a true ferromagnetic-ferroelectric system with a
coupling between the respective order parameters in nanoscale BiFeO_3.Comment: 13 pages including 4 figures; pdf only; submitted to Appl. Phys. Let
Exposure to high-rise buildings negatively influences affect: evidence from real world and 360-degree video
Cities are densifying at a rapid rate, and accordingly, are constructing high-rise buildings to accommodate more people. The aim of this study was to quantify the physiological and psychological impacts of being in the presence of high-rise buildings in Central London, in a real and virtual 360-degree video environment. Using a within-subjects design, participants were exposed to a low-rise and high-rise building. While exposed, participants were monitored for electrodermal activity. They were also administered the Self-Assessment Manikin measure and a cognitive appraisal questionnaire. Participants rated the high-rise building environment to be less open, less friendly and rated themselves to feel less happy and have less sense of control, as compared to low-rise buildings. We found these effects in both the real world (n = 16) and a 360-degree video setting (n = 121). These findings suggest that city environments populated with high-rise buildings can have negative impacts on urban dwellers. Furthermore, this study provides a methodology to examine how individuals respond to the built environment and stand to inform urban design and architectural practices
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