scholarly journals Laser-Driven High-Velocity Microparticle Launcher In Atmosphere And Under Vacuum

2019 ◽  
Author(s):  
David Veysset ◽  
Yuchen Sun ◽  
Steven E. Kooi ◽  
Keith A. Nelson
Keyword(s):  
Cold Spray ◽  
High Velocity ◽  
Optical Methods ◽  
Metallic Coatings ◽  
Spray Method ◽  
Wide Range ◽  
Gas Guns ◽  
Projectile Impacts

Abstract The study of high-velocity microparticles is important to a wide range of both space and terrestrial applications. In space, high- and hyper-velocity micro-debris and micrometeorites, while also a subject of study, pose a threat to equipment and personnel integrity [1–4]. On earth, high-velocity microparticle impact can be, for instance, utilized for therapeutic purposes in the field of biolistics [5] or to build metallic coatings via the cold spray method [6]. While macroscale projectile impacts have been studied using well established experimental tools, such as light-gas guns, optical methods are gaining interest in the field of micro-particle impacts.

Cold Spray Process ~ Overview and Application Trends ~

2004 ◽  
Vol 449-452 ◽  
pp. 1305-1308 ◽  
Author(s):  
Kazuhiko Sakaki
Keyword(s):  
Cold Spray ◽  
Gas Flow ◽  
Solid Phase ◽  
Ambient Air ◽  
Nozzle Geometry ◽  
Cold Spray Process ◽  
Spray Process ◽  
Spray Method ◽  
Wide Range ◽  
Metal Metal

In Cold Spray method, a coating is formed by exposing a substrate to high velocity solid-phase particles, which have been accelerated by supersonic gas flow at a temperature much lower than the melting or softening temperature of the feedstock. Therefore, the nozzle geometry is important with regard to the cold spray method. This Cold Spray process is an exciting new spray technology that has the potential to overcome limitations of more traditional thermal spray processes for some important commercial applications. With this emerging technology, it is possible for the first time to rapidly deposit thin or very thick layers (mm to cm+) of a wide range of metals, and even some composite materials, without melting or vaporization, at or near room temperature, in an ambient air environment. Some potential areas of interest include:  corrosion protection,  wear reduction, highly conductive coatings (electrical or thermal), metal/glass or metal/ceramic joints (with less residual stress), ceramic/metal or graded metal/metal composites,  thick deposits (mm to several cm range), reclamation of worn or mis-machined parts, metallization of glass or ceramics. The applications of Cold Spray can be examined in the field of an automobile and a rocket engine.

scholarly journals Kinematics of Nuclei of Sc Galaxies

1980 ◽  
Vol 5 ◽  
pp. 191-191
Author(s):  
V. C. Rubin
Keyword(s):  
High Velocity ◽  
Stellar Population ◽  
Hii Regions ◽  
Emission Lines ◽  
High Luminosity ◽  
Rotation Curves ◽  
Velocity Gradients ◽  
Wide Range ◽  
Central Regions ◽  
Velocity Dispersions

For a sample of 21 Sc galaxies with a wide range of luminosities, of radii, and of masses, W. K. Ford and I have obtained spectra and determined rotation curves. By their kinematical behavior in their central regions, the Sc’s can be separated into two groups. Some galaxies, generally small and of low luminosity, have shallow central velocity gradients, reflecting their low central masses and densities. Other galaxies, most often large ones of high luminosity, have steep central velocity gradients. One reason this separation by central velocity gradients is of interest is because these galaxies exhibit other significant spectral differences which go hand-in-hand with the kinematical differences.The small, low luminosity galaxies show emission lines of Hα and [NII], with nuclear Ha sharp and stronger than [NII], and little or no stellar nuclear continuum, just as conventional HII regions. In contrast, the high luminosity galaxies show broad nuclear emission, with [NII] stronger than Ha. These galaxies have a strong red stellar continuum, arising from a red stellar population. The cause of the Hα[NII] intensity reversal in the nuclei of some galaxies remains unknown. However, the strong [NII] emission in generally high luminosity galaxies with massive nuclei, nuclei which show strong red continua, suggests that [Nil] intensity correlates with nuclear luminosity, and in turn with the density and velocity properties of the nuclear populations. We would expect high velocity dispersions and high bulge luminosities for galaxies with strong nuclear [NII] and steep central velocity gradients.

The effect of cell tilting on turbulent thermal convection in a rectangular cell

2014 ◽  
Vol 762 ◽  
pp. 273-287 ◽  
Author(s):  
Shuang-Xi Guo ◽  
Sheng-Qi Zhou ◽  
Xian-Rong Cen ◽  
Ling Qu ◽  
Yuan-Zheng Lu ◽  
...  
Keyword(s):  
High Velocity ◽  
Large Scale ◽  
Velocity Measurements ◽  
Cell Width ◽  
Rectangular Cell ◽  
Aspect Ratios ◽  
Wide Range ◽  
Almost All ◽  
Temperature And Velocity Fields ◽  
Pronounced Reduction

AbstractIn this study the influence of cell tilting on flow dynamics and heat transport is explored experimentally within a rectangular cell (aspect ratios ${\it\Gamma}_{x}=1$ and ${\it\Gamma}_{y}=0.25$). The measurements are carried out over a wide range of tilt angles ($0\leqslant {\it\beta}\leqslant {\rm\pi}/2\ \text{rad}$) at a constant Prandtl number ($\mathit{Pr}\simeq 6.3$) and Rayleigh number ($\mathit{Ra}\simeq 4.42\times 10^{9}$). The velocity measurements reveal that the large-scale circulation (LSC) is sensitive to the symmetry of the system. In the level case, the high-velocity band of the LSC concentrates at about a quarter of the cell width from the boundary. As the cell is slightly tilted (${\it\beta}\simeq 0.04\ \text{rad}$), the position of the high-velocity band quickly moves towards the boundary. With increasing ${\it\beta}$, the LSC changes gradually from oblique ellipse-like to square-like, and other more complicated patterns. Oscillations have been found in the temperature and velocity fields for almost all ${\it\beta}$, and are strongest at around ${\it\beta}\simeq 0.48\ \text{rad}$. As ${\it\beta}$ increases, the Reynolds number ($\mathit{Re}$) initially also increases, until it reaches its maximum at the transition angle ${\it\beta}=0.15\ \text{rad}$, after which it gradually decreases. The cell tilting causes a pronounced reduction of the Nusselt number ($\mathit{Nu}$). As ${\it\beta}$ increases from 0 to 0.15, 1.05 and ${\rm\pi}/2\ \text{rad}$, the reduction of $\mathit{Nu}$ is approximately 1.4 %, 5 % and 18 %, respectively. Over the ranges of $0\leqslant {\it\beta}\leqslant 0.15\ \text{rad}$, $0.15\leqslant {\it\beta}\leqslant 1.05\ \text{rad}$ and $1.05\leqslant {\it\beta}\leqslant {\rm\pi}/2\ \text{rad}$, the decay slopes are $8.57\times 10^{-2}$, $3.27\times 10^{-2}$ and $0.24\ \text{rad}^{-1}$, respectively.

The Spread of Corrosion of the Deposited Material Using the Cold Spray Method

2021 ◽  
Vol 105 (1) ◽  
pp. 355-369
Author(s):  
Tomáš Binar ◽  
Jana Zimáková ◽  
Jakub Steiniger ◽  
Lukáš Řehořek ◽  
Petr Křivík ◽  
...  
Keyword(s):  
Electron Microscope ◽  
Cold Spray ◽  
Surface Resistance ◽  
Spray Method ◽  
Aluminum Material

A layer of copper was applied to the base aluminum material using the cold spray method (cold kinetic deposition). The samples were exposed to corrosion in a salt chamber for 100, 200 and 300 hours. The change in the size of the internal and surface resistance of the samples was monitored. The corrosion results were also examined using an electron microscope.

scholarly journals Properties of the protective powder coating made on the basis of nickel and received by the cold spray method

2019 ◽  
Vol 1281 ◽  
pp. 012041
Author(s):  
L A Krivina ◽  
I N Tsareva ◽  
Yu P Tarasenko ◽  
O B Berdnik
Keyword(s):  
Cold Spray ◽  
Powder Coating ◽  
Spray Method

scholarly journals The X-ray view of the Wolf-Rayet stars

1995 ◽  
Vol 163 ◽  
pp. 429-437
Author(s):  
A.M.T. Pollock
Keyword(s):  
High Velocity ◽  
X Ray ◽  
Wide Range ◽  
Colliding Winds

Ever since the earliest work, X-ray observations have been central in the chequered development of the study of interacting high-velocity winds in binaries. This review assesses how confidently the observations of Wolf-Rayet stars may be interpreted as the result of colliding winds, drawing attention to the wide range of X-ray luminosities even among the relatively bright binaries. Although the data do not generally conform to the simplest binary models, some suggestions are made to reconcile theory and observation.

scholarly journals Spectroscopic diagnostics of T Tauri inner winds

2007 ◽  
Vol 3 (S243) ◽  
pp. 171-182 ◽  
Author(s):  
Suzan Edwards
Keyword(s):  
Velocity Component ◽  
High Velocity ◽  
T Tauri Stars ◽  
Interaction Region ◽  
Spectroscopic Diagnostics ◽  
T Tauri ◽  
Spectral Diagnostics ◽  
Launch Site ◽  
Wide Range

AbstractThe role of the star-disk interaction region in launching the high velocity component of accretion-driven outflows is examined. Spectroscopic indicators of high velocity inner winds have been recognized in T Tauri stars for decades, but identifying the wind launch site and the accompanying mass loss rates has remained elusive. A promising new diagnostic is He I λ10830, whose metastable lower level results in a powerful probe of the geometry of the outflowing gas in the interaction region. This, together with other atomic and molecular spectral diagnostics covering a wide range of excitation and ionization states, suggests that more than one launch site of the innermost wind is operational in most accreting stars.

scholarly journals LaiPen LP 100 – a new device for estimating forest ecosystem leaf area index compared to the etalon: A methodologic case study

2018 ◽  
Vol 64 (No. 11) ◽  
pp. 455-468
Author(s):  
Jakub Černý ◽  
Jan Krejza ◽  
Radek Pokorný ◽  
Pavel Bednář
Keyword(s):  
Leaf Area Index ◽  
Leaf Area ◽  
Optical Methods ◽  
Ecological Studies ◽  
Area Index ◽  
New Device ◽  
Area Efficiency ◽  
Wide Range ◽  
World Standard

Fast and precise leaf area index (LAI) estimation of a forest stand is frequently needed for a wide range of ecological studies. In the presented study, we compared side-by-side two instruments for performing LAI estimation (i.e. LaiPen LP 100 as a “newly developed device” and LAI-2200 PCA as the “world standard”), both based on indirect optical methods for performing LAI estimation in pure Norway spruce (Picea abies (Linnaeus) H. Karsten) stands under different thinning treatments. LAI values estimated by LaiPen LP 100 were approximate 5.8% lower compared to those measured by LAI-2200 PCA when averaging all collected data regardless of the thinning type. Nevertheless, when we considered the differences among LAI values at each measurement point within a regular grid, LaiPen LP 100 overestimated LAI values compared to those from LAI-2200 PCA on average by 1.4%. Therefore, both instruments are comparable. Similar LAI values between thinning from above (A) and thinning from below (B) approaches were indirectly detected by both instruments. The highest values of canopy production index and leaf area efficiency were observed within the stand thinned from above (plot A).

Sign in / Sign up

Export Citation Format

Share Document