No abstract

We establish the dominant effect of anisotropic weak localization ͑WL͒ in three dimensions ͑3D͒ associated with a propagative Fermi surface on the conductivity correction in heavily nitrogen-doped ultrananocrystalline diamond ͑UNCD͒ films based on magnetoresistance studies at low temperatures. Also, low-temperature electrical conductivity can show weakly localized transport in 3D combined with the effect of electron-electron interactions in these materials, which is remarkably different from the conductivity in two-dimensional WL or strong localization regime. The corresponding dephasing time of electronic wave functions in these systems described as ϳT −p with p Ͻ 1, follows a relatively weak temperature dependence compared to the generally expected nature for bulk dirty metals having p Ն 1. The temperature dependence of Hall ͑electron͒ mobility together with an enhanced electron density has been used to interpret the unusual magnetotransport features and show delocalized electronic transport in these n-type UNCD films, which can be described as lowdimensional superlattice structures.

No abstract

The aerodynamics of projectiles used in various sports is investigated via experiments in a low speed wind tunnel. Force measurements are carried out on actual artifacts at speeds in the range of 15-75 m/s. The sports considered include golf, field hockey, soccer, baseball, tennis, cricket, volleyball, and badminton. Both synthetic and duck-feather models of shuttle-cocks used in badminton are considered. The variation of the coefficient of drag, CD, with Reynolds number, Re, is quite different for the two models. The deformation of the synthetic model increases significantly with an increase in speed, leading to a decrease in CD with an increase in Re. The duck-feather model, on the other hand, does not undergo such severe deformations. Force measurements for a baseball are carried out for three different orientations of its seam with the free-stream flow. Variation of CD with Re for two internationally approved brands of golf balls is presented for the first time in the open literature. The data are compared with those for a ball used in field hockey, which also has dimples on its surface, albeit of different sizes and distributions. Force measurements are carried out on a new cricket ball as well as one whose surface is manually roughened to resemble a ball that has been in play for about 40 overs (=240 deliveries). The study brings out the regimes of conventional- and reverse-swing and their dependence on the surface roughness of the ball. Experiments on balls with differential roughness of the two hemispheres of the ball are utilized to study the “contrast-swing.” Particle Image Velocimetry measurements are carried out for the 3D-printed model of a new cricket ball to explore the phenomena of conventional- and reverse-swing. Experiments on a tennis ball bring out the role of the fuzz in the transition of the boundary layer on its surface; a near-constant CD for the entire range of Re that is studied is observed. The brands of a soccer ball and volleyball that are tested exhibit very similar behaviour. In the supercritical regime, an increase in CD is followed by its decrease with an increase in Re.

Cough is a symptom in over a hundred respiratory diseases. The audio features in cough signals contain erudition about the predicament of the respiratory system. Using deep learning or signal processing, these features can be used to build an effective disease prediction system. However, cough analysis remains an area that has received scant attention from machine learning researchers. This can be attributed to several factors such as inefficient ancillary systems, high expenses in obtaining datasets, or difficulty in building classifiers. This article categorized and reviewed the current progress on cough audio analysis for the classification of pulmonary diseases. It also explored potential future issues in research. In addition, it proposed a model for the classification of 10 serious pulmonary ailments commonly seen in Indian adolescents. The proposed model is evaluated against four existing state-of-the-art techniques in the literature.