5,922 research outputs found
Study of Air Curtain in Context of Individual Protection from Exposure to Coronavirus (SARS-CoV-2) Contained in Cough-Generated Fluid Particles
The ongoing respiratory COVID-19 pandemic has heavily impacted the social and
private lives of the majority of the global population. This infection is
primarily transmitted via virus-laden fluid particles (i.e., droplets and
aerosols) that are formed in the respiratory tract of infected individuals and
expelled from the mouth in the course of breathing, talking, coughing, and
sneezing. To mitigate the risk of virus transmission, in many places of the
world, the public has been asked or even obliged to use face covers. It is
plausible that in the years ahead we will see the use of face masks, face
shields and respirators become a normal practice in our life. However, wearing
face covers is uncomfortable in some situations, like, for example, in summer
heat, while staying on beaches or at hotel swimming pools, doing exercises in
gyms, etc. Also, most types of face cover become contaminated with time and
need to be periodically replaced or disinfected. These nuisances are caused by
the fact that face covers are based on material barriers, which prevent inward
and outward propagation of aerosol and droplets containing the pathogen.
Applying well established gas-particle flow formalism, we study a non-material
based protection barrier created by a flow of well directed down stream of air
across the front of the open face. The~protection is driven by dragging
virus-laden particles inside the width of the air flow and hence, as a
consequence, displacing them away from their primary trajectories. The study,
shows that such, potentially portable, air curtains can effectively provide
both inward and outward protection and serve as an effective personal
protective equipment (PPE) mitigating human to human transmission of virus
infection like COVID-19.Comment: 17 pages, 4 figures, version accepted for publication in Physics MDP
Orientation and symmetry control of inverse sphere magnetic nanoarrays by guided self-assembly
Inverse sphere shaped Ni arrays were fabricated by electrodeposition on Si through the guided self-assembly of polystyrene latex spheres in Si/SiO2 patterns. It is shown that the size commensurability of the etched tracks is critical for the long range ordering of the spheres. Moreover, noncommensurate guiding results in the reproducible periodic triangular distortion of the close packed self-assembly. Magnetoresistance measurements on the Ni arrays were performed showing room temperature anisotropic magnetoresistance of 0.85%. These results are promising for self-assembled patterned storage media and magnetoresistance devices
Three-dimensional light bullets in a Bragg medium with carbon nanotubes
We present a theoretical study of the propagation of three-dimensional
extremely short electromagnetic pulses (a.k.a. light bullets) through a Bragg
medium containing an immersed array of carbon nanotubes. We demonstrate the
possible stable propagation of such light bullets. In particular, our results
suggest these light bullets can carry information about the Bragg medium
itself.Comment: To appear in Appl. Phys.
Verification of model of calculation of intra-chamber parameters in hybrid solid-propellant rocket engines
On the basis of obtained analytical estimate of characteristics of hybrid solid-propellant rocket engine verification of earlier developed physical and mathematical model of processes in a hybrid solid-propellant rocket engine for quasi-steady-state flow regime was performed. Comparative analysis of calculated and analytical data indicated satisfactory comparability of simulation results
Analysis of a hadron beam in five-dimensional phase space
We conduct a detailed measurement and analysis of a hadron beam in
five-dimensional phase space at the Spallation Neutron Source Beam Test
Facility. The measurement's resolution and dynamic range are sufficient to
image sharp, high-dimensional features in low-density regions of phase space.
To facilitate the complex task of feature identification in the
five-dimensional phase space, we develop several analysis and visualization
techniques, including non-planar slicing. We use these techniques to examine
the transverse dependence of longitudinal hollowing and longitudinal dependence
of transverse hollowing in the distribution. This analysis strengthens the
claim that low-dimensional projections do not adequately characterize
high-dimensional phase space distributions in low-energy hadron acceleratorsComment: 13 pages; 15 figures; submitted to Physical Review Accelerators and
Beams (PRAB
Analytical estimation of particle shape formation parameters in a plasma-chemical reactor
Analytical estimation of particle shape formation parameters in a plasma-chemical reactor implementing the process of thermochemical decomposition of liquid droplet agents (precursors) in the flow of a hightemperature gaseous heat-transfer medium was obtained. The basic factor which determines the process is the increase of concentration of a dissolved salt precursor component at the surface of a liquid particle due to solvent evaporation. According to the physical concept of the method of integral balance the diffusion process of concentration change is divided into two stages: the first stage is when the size of gradient layer does not reach the center of a spherical droplet and the second stage when the concentration at the center of a liquid droplet begins to change. The solutions for concentration fields were found for each stage using the method of integral balance taking into account the formation of salt precipitate when the concentration at the surface of the droplet reaches certain equilibrium value. The results of estimation of the influence of various reactor operation parameters and characteristics of initial solution (precursor) on the morphology of particles formed - mass fraction and localization of salt precipitate for various levels of evaporation
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