Search results for "wave"
showing 10 items of 6009 documents
Multi-resolution anisotropy studies of ultrahigh-energy cosmic rays detected at the Pierre Auger Observatory
2017
We report a multi-resolution search for anisotropies in the arrival directions of cosmic rays detected at the Pierre Auger Observatory with local zenith angles up to $80^\circ$ and energies in excess of 4 EeV ($4 \times 10^{18}$ eV). This search is conducted by measuring the angular power spectrum and performing a needlet wavelet analysis in two independent energy ranges. Both analyses are complementary since the angular power spectrum achieves a better performance in identifying large-scale patterns while the needlet wavelet analysis, considering the parameters used in this work, presents a higher efficiency in detecting smaller-scale anisotropies, potentially providing directional informa…
Application of Molecular Topology for the Prediction of Reaction Yields and Anti-Inflammatory Activity of Heterocyclic Amidine Derivatives
2011
Topological-mathematical models based on multiple linear regression analyses have been built to predict the reaction yields and the anti-inflammatory activity of a set of heterocylic amidine derivatives, synthesized under environmental friendly conditions, using microwave irradiation. Two models with three variables each were selected. The models were validated by cross-validation and randomization tests. The final outcome demonstrates a good agreement between the predicted and experimental results, confirming the robustness of the method. These models also enabled the screening of virtual libraries for new amidine derivatives predicted to show higher values of reaction yields and anti-infl…
Assessment of the tibia using ultrasonic guided waves in pubertal girls
2002
The purpose of this study was to compare low frequency ultrasonic guided wave measurements with established ultrasound and bone density measurements in terms of their ability to characterize the tibia in pubertal girls. Subjects were 12-14-year-old girls ( n=106) who were participating in a calcium and vitamin D intervention study. A prototype low frequency pulse transmission device consisting of a uniaxial scanning mechanism and low frequency transducers orientated perpendicularly to the limb was used to measure two ultrasound velocities in the tibia. The first velocity, V1, was that of the first arriving signal, similar to that measured by existing commercial tibial ultrasound devices. Th…
A reanalysis of spinal motion during vibration
1987
Calibrated film of the motion of the lumbar spine during vibration was reanalysed, making use of a number of computer based techniques to improve accuracy and reduce measurement noise. The results demonstrated resonant behaviour at about 4 Hz and indicated that at vibration levels of the order of 1 m/s2 there exists bending of the order of 1° (peak to peak) between adjacent vertebrae in the lumbar spine. The bending is complex and involves phase differences along the spine and possibly a rocking motion of the pelvis.
How Important is the Reproduction Technique for the Perception of Spaciousness in Music?
2016
Sound fields are preferred when spaciousness is perceived. “Spaciousness means that auditory events, in a characteristic way, are themselves perceived as being spread out in an extended region of space”. The author’s former study (2012) investigated the perception of spaciousness of five musical genres. Participants evaluated spaciousness while listening to music with loudspeakers. Resulting, these genres allowed classifications of spatial features such as “big”, “wide” and “open”. A new idea of conducting listening tests has arisen using wave field synthesis instead of headphones. Firstly, this study aims to reveal the perceptional characteristics of spaciousness in music itself with headp…
Microwave-assisted synthesis of semiconductor nanoparticles in water/oil microemulsion
2005
Stable CdS and ZnS nanoparticles with exalted luminescence properties have been obtained in water/sodium bis (2-ethylhexyl) sulfosuccinate (AOT)/n-heptane microemulsion using microwave in order to take away selectively water molecules from microemulsion system. The nanoparticles synthesis was performed using a microwave exposure set-up opportunely assembled that allows irradiating the reactor with microwave of 2.45 GHz maintaining constant the temperature. The nanoparticles growth kinetics, as a function of irradiation time, was performed by means of UV-Vis spectroscopy. Information about the structural changes that microemulsion undergoes when irradiated with microwave was obtained by mean…
Optical Properties of III-V Nanowires and Their Application for Charge Transport and Single-Photon Emission
2012
This work covers the optical characterization of III-V semiconductor nanowires and their application for charge transport and for single-photon emission. InAs nanowires have been investigated by Raman scattering and PL spectroscopy. The possibility to grow nanowires with a crystal structure different from its bulk counterpart has aroused a lot of interest in their optical and electronic properties. Here, the optical phonon modes of wurtzite InAs nanowires have been studied by polarized Raman scattering. For the first time, Raman measurements on a single InAs nanowire have revealed the A1(TO) and E2h optical phonon modes of the wurtzite structure. Additional resonant Raman scattering experim…
Technical and economical comparison between NdFeB and hard ferrites linear electrical generators from sea waves
2015
In this paper the authors perform a technical-economic comparison of two different Tubular Permanent Magnet Linear Machines for sea waves generation by using finite elements analysis. The first configuration includes ferrite rings while the second configuration includes neodymium-iron-boron rings. In order to compare the two types in economic and technical terms, a detailed analysis of the main figures of merit of the two configurations has been carried out. In particular, significant data such as flux distribution, rated voltage and current, axial force, electric power, realization cost and maintenance cost have been compared.
Population Properties of Compact Objects from the Second LIGO-Virgo Gravitational-Wave Transient Catalog
2021
Abbott, R., et al. (LIGO and Virgo Collaboration)
Increasing the Astrophysical Reach of the Advanced Virgo Detector via the Application of Squeezed Vacuum States of Light
2019
Current interferometric gravitational-wave detectors are limited by quantum noise over a wide range of their measurement bandwidth. One method to overcome the quantum limit is the injection of squeezed vacuum states of light into the interferometer's dark port. Here, we report on the successful application of this quantum technology to improve the shot noise limited sensitivity of the Advanced Virgo gravitational-wave detector. A sensitivity enhancement of up to 3.2±0.1 dB beyond the shot noise limit is achieved. This nonclassical improvement corresponds to a 5%-8% increase of the binary neutron star horizon. The squeezing injection was fully automated and over the first 5 months of the thi…