scholarly journals Suppression of ionospheric irregularity due to auroral particle impact

2021 ◽  
Author(s):  
Toru Takahashi ◽  
Andres Spicher ◽  
Francesca Di Mare ◽  
Douglas E. Rowland ◽  
Robert F. Pfaff ◽  
...  
Keyword(s):  
Ionospheric Irregularity ◽  
Particle Impact

Ionospheric irregularity physics modelling

1982 ◽  
Author(s):  
S. OSSAKOW ◽  
M. KESKINEN ◽  
S. ZALESAK
Keyword(s):  
Ionospheric Irregularity

Prediction of particle distribution and particle impact erosion in inclined cavities

2017 ◽  
Vol 305 ◽  
pp. 562-571 ◽  
Author(s):  
Zhe Lin ◽  
Yifan Zhang ◽  
Yi Li ◽  
Xiaojun Li ◽  
Zuchao Zhu
Keyword(s):  
Particle Distribution ◽  
Particle Impact ◽  
Impact Erosion

The Technical Development for Increasing ROP with Particle Impact Drilling in China

2014 ◽  
Vol 904 ◽  
pp. 292-295 ◽  
Author(s):  
Jian Zhao ◽  
Yi Ji Xu
Keyword(s):  
Field Test ◽  
Hard Rock ◽  
Rock Breaking ◽  
Particle Impact ◽  
Sound Effect ◽  
Deep Well ◽  
Working Principle ◽  
Hard Formation ◽  
Field Test Result ◽  
Test Result

Field test of particle impact drilling (PID) technology was firstly carried out in deep well and hard formation in Sichuan province china on Oct. 2013. The test formation was named Xu Jiahe, which was very difficult to penetration. Field test result shows that the ROP (rate of penetration) was nearly doubled by this technology. It indicates that there is a profound application prospect of particle impact drilling, especially for hard rock formation. In this paper, the equipment and working principle was analyzed. The experiment and simulation results showed that the rock breaking efficiency was highly increased by this technology. The details of this field test were presented too in this paper that proved the sound effect of PID.

Effect of Particle Impact Velocity on Cone Crack Shape in Ceramic Material

2005 ◽  
Vol 297-300 ◽  
pp. 1321-1326 ◽  
Author(s):  
Sang Yeob Oh ◽  
Hyung Seop Shin
Keyword(s):  
Impact Velocity ◽  
Computational Simulation ◽  
Back Surface ◽  
Particle Impact ◽  
Cone Crack ◽  
Crack Shape ◽  
The Impact ◽  
Particle Impact Velocity ◽  
Sic Particle ◽  
Ring Cracks

The damage behaviors induced in a SiC by a spherical particle impact having a different material and size were investigated. Especially, the influence of the impact velocity of a particle on the cone crack shape developed was mainly discussed. The damage induced by a particle impact was different depending on the material and the size of a particle. The ring cracks on the surface of the specimen were multiplied by increasing the impact velocity of a particle. The steel particle impact produced the larger ring cracks than that of the SiC particle. In the case of the high velocity impact of the SiC particle, the radial cracks were generated due to the inelastic deformation at the impact site. In the case of the larger particle impact, the morphology of the damages developed were similar to the case of the smaller particle one, but a percussion cone was formed from the back surface of the specimen when the impact velocity exceeded a critical value. The zenithal angle of the cone cracks developed into the SiC decreased monotonically as the particle impact velocity increased. The size and material of a particle influenced more or less on the extent of the cone crack shape. An empirical equation was obtained as a function of impact velocity of the particle, based on the quasi-static zenithal angle of the cone crack. This equation will be helpful to the computational simulation of the residual strength in ceramic components damaged by the particle impact.

The effect of spacecraft descent engine plumes on spore transfer to planetary surfaces: Phoenix as a test case

2011 ◽  
Vol 10 (4) ◽  
pp. 335-340 ◽  
Author(s):  
J.R. Marshall ◽  
R.L. Mancinelli
Keyword(s):  
Atmospheric Pressure ◽  
Laboratory Experiments ◽  
Particle Impact ◽  
Test Case ◽  
Surrounding Area ◽  
Planetary Protection ◽  
Engine Thrust ◽  
Exhaust Plumes ◽  
Microbial Contaminants ◽  
Different Parts

AbstractLaboratory experiments were conducted to determine the effect of descent-engine plumes on the scouring of surface (microbial) contaminants from a spacecraft. A simulated touchdown of a half-scale lander engine and deck configuration was conducted at Mars atmospheric pressure in the NASA Ames Planetary Aeolian Laboratory. Low-density particles were used for the soil simulant to emulate the lower Martian gravity. The underside of the model had small witness plates with controlled microbial surface populations and particle impact detectors. For both steady-state engine thrust (Viking) and pulsed engine thrust (Phoenix), the exhaust plumes from the engines violently excavated the soil and produced particle-laden eddies beneath the lander that sandblasted the lander underside. The result was nearly complete erosion of microbial contaminants from the spacecraft model with their subsequent deposition in the surrounding area. It is concluded that different planetary protection cleanliness levels for different parts of a spacecraft do not necessarily prevent soil contamination because these cleaning strategies evolved without consideration of the effects of the descent engine plumes.

Dynamics and Performance of a Harmonically Excited Vertical Impact Damper

2008 ◽  
Vol 130 (2) ◽  
Author(s):  
Sanjiv Ramachandran ◽  
George Lesieutre
Keyword(s):  
Loss Factor ◽  
Vertical Direction ◽  
Theoretical Models ◽  
Coefficient Of Restitution ◽  
Numerical Continuation ◽  
Particle Impact ◽  
Impact Damper ◽  
High Loss ◽  
Wide Range ◽  
And Performance

Particle impact dampers (PIDs) have been shown to be effective in vibration damping. However, our understanding of such dampers is still limited, based on the theoretical models existing today. Predicting the performance of the PID is an important problem, which needs to be investigated more thoroughly. This research seeks to understand the dynamics of a PID as well as those parameters which govern its behavior. The system investigated is a particle impact damper with a ceiling, under the influence of gravity. The base is harmonically excited in the vertical direction. A two-dimensional discrete map is obtained, wherein the variables at one impact uniquely dictate the variables at the next impact. This map is solved using a numerical continuation procedure. Periodic impact motions and “irregular” motions are observed. The effects of various parameters such as the gap clearance, coefficient of restitution, and the base acceleration are analyzed. The dependence of the effective damping loss factor on these parameters is also studied. The loss factor results indicate peak damping for certain combinations of parameters. These combinations of parameters correspond to a region in parameter space where two-impacts-per-cycle motions are observed over a wide range of nondimensional base accelerations. The value of the nondimensional acceleration at which the onset of two-impacts-per-cycle solutions occurs depends on the nondimensional gap clearance and the coefficient of restitution. The range of nondimensional gap clearances over which two-impacts-per-cycle solutions are observed increases as the coefficient of restitution increases. In the regime of two-impacts-per-cycle solutions, the value of nondimensional base acceleration corresponding to onset of these solutions initially decreases and then increases with increasing nondimensional gap clearance. As the two-impacts-per-cycle solutions are associated with high loss factors that are relatively insensitive to changing conditions, they are of great interest to the designer.

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