scholarly journals Observable Signatures of the Ejection Speed of Interstellar Objects from Their Birth Systems

2020 ◽  
Vol 903 (1) ◽  
pp. L20
Author(s):  
Amir Siraj ◽  
Abraham Loeb
Keyword(s):  
Ejection Speed

scholarly journals Investigation of Break-Up, Splash, and Fingerlike Instabilities for a Large Water Slug Impact

2006 ◽  
Author(s):  
Richard A. Jepsen ◽  
Sam S. Yoon ◽  
Scott C. James
Keyword(s):  
Large Scale ◽  
Model Simulation ◽  
Surrounding Medium ◽  
Impact Angle ◽  
Droplet Impact ◽  
Droplet Shape ◽  
Instability Theory ◽  
Ejection Speed ◽  
Large Water ◽  
New Phenomena

The fluid physics of splashing, spreading, and dispersion of a large-scale water droplet is investigated both experimentally and with model simulation. Several new phenomena of the droplet impact beyond conventional Rayleigh-Taylor instability theory are reported. First, our experimental data show that the number of fingers or instabilities along the spreading rim cannot be predicted by Allen's (1975) Rayleigh-Taylor equation. Second, we report that the surrounding medium (air) along with impact angle and droplet shape upon impact affect ejection velocity and splashing. Finally, the fundamental instability of the finger formation along the spreading rim may be due to interactions initiated by the compressed and displaced air, rather than the spreading of the liquid decelerating through the air. Several important correlations between the droplet impact velocities, the amount of spray ejected, the spray ejection speed, and the number of fingers or instabilities are presented.

scholarly journals Fabrication of Core-Shell PLGA-Chitosan Microparticles Using Electrospinning: Effects of Polymer Concentration

2017 ◽  
Vol 2017 ◽  
pp. 1-8 ◽  
Author(s):  
Nguyen Thi Hiep ◽  
Nguyen Dai Hai ◽  
Vo Van Toi
Keyword(s):  
Glycolic Acid ◽  
Polymer Concentration ◽  
Core Shell ◽  
The Core ◽  
Ft Ir ◽  
Ejection Speed ◽  
Diphenyl Tetrazolium Bromide ◽  
Product Outcome ◽  
Labeling Method ◽  
Fluorescence Observation

This investigation aims to fabricate the core-shell microparticles composed of poly(lactic-co-glycolic acid) and chitosan (PLGA-CS MPs) using electrospinning. The challenge of using electrospinning is that it has many parameters which change product outcome if any single parameter is changed. However, the advantage of this system is that we can fabricate either micro/nanofibers or micro/nanoparticles. To learn about the effect of liquid concentration, the electrospinning parameters (voltage, needle sizes, distance from needle to collector, and ejection speed) were fixed while the concentration of PLGA or chitosan was varied. The results showed that PLGA microparticles can be fabricated successfully when the concentration of PLGA is smaller than 10 wt%. Presence of the chitosan shell was confirmed by zeta potential measurements, FT-IR, optical observation, and fluorescence observation. Thickness of the chitosan shell can be controlled by changing the concentration of chitosan and measured by fluorescamine labeling method. Moreover, SEM observation showed that concentration of chitosan affected the size of PLGA-CS microparticles. The MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) assay test showed that PLGA-CS microparticles possess excellent biocompatibility.

scholarly journals RELATIONSHIP OF EUV IRRADIANCE CORONAL DIMMING SLOPE AND DEPTH TO CORONAL MASS EJECTION SPEED AND MASS

2016 ◽  
Vol 830 (1) ◽  
pp. 20 ◽  
Author(s):  
James Paul Mason ◽  
Thomas N. Woods ◽  
David F. Webb ◽  
Barbara J. Thompson ◽  
Robin C. Colaninno ◽  
...  
Keyword(s):  
Coronal Mass Ejection ◽  
Ejection Speed ◽  
Mass Ejection ◽  
Relationship Of ◽  
Coronal Dimming

scholarly journals Modeling Early Clustering of Impact-induced Ejecta Particles Based on Laboratory and Numerical Experiments

2021 ◽  
Vol 2 (6) ◽  
pp. 237
Author(s):  
Kanon Nakazawa ◽  
Satoshi Okuzumi ◽  
Kosuke Kurosawa ◽  
Sunao Hasegawa
Keyword(s):  
Pattern Formation ◽  
Initial Conditions ◽  
Heterogeneous Material ◽  
Hypervelocity Impact ◽  
Inelastic Collisions ◽  
Final Size ◽  
Ejection Speed ◽  
The Difference ◽  
The Impact ◽  
Previous Prediction

Abstract A projectile impact onto a granular target produces an ejecta curtain with heterogeneous material distribution. Understanding how the heterogeneous pattern forms is potentially important for understanding how crater rays form. Previous studies predicted that the pattern formation is induced by inelastic collisions of ejecta particles in early stages of crater formation and terminated by the ejecta’s expanding motion. In this study, we test this prediction based on a hypervelocity impact experiment together with N-body simulations where the trajectories of inelastically colliding granular particles are calculated. Our laboratory experiment suggests that pattern formation is already completed on a timescale comparable to the geometrical expansion of the ejecta curtain, which is ∼10 μs in our experiment. Our simulations confirm the previous prediction that the heterogeneous pattern grows through initial inelastic collisions of particle clusters and subsequent geometric expansion with no further cluster collisions. Furthermore, to better understand the two-stage evolution of the mesh pattern, we construct a simple analytical model that assumes perfect coalescence of particle clusters upon collision. The model shows that the pattern formation is completed on the timescale of the system’s expansion independently of the initial conditions. The model also reproduces the final size of the clusters observed in our simulations as a function of the initial conditions. It is known that particles in the target are ejected at lower speeds with increased distance to the impact point. The difference in the ejection speed of the particles may result in the evolution of the mesh pattern into rays.

scholarly journals Haemodynamic effects of hyperventilation on healthy men with different levels of autonomic tone

2020 ◽  
Vol 11 (1) ◽  
pp. 13-21
Author(s):  
V. A. Zavhorodnia ◽  
O. I. Androshchuk ◽  
T. H. Kharchenko ◽  
L. I. Kudii ◽  
S. O. Kovalenko
Keyword(s):  
Recovery Period ◽  
Peripheral Resistance ◽  
Stroke Index ◽  
Autonomic Tone ◽  
Polar Wind ◽  
Cardiorespiratory System ◽  
Phase Duration ◽  
Ejection Speed ◽  
Different Levels ◽  
Ejection Phase

The topicality of the research is stipulated by insufficient study of the correlation between the functional state of the cardiorespiratory system and autonomic tone. The goal of the research was to analyze the changes of central haemodynamics with 10-minute regulated breathing at the rate of 30 cycles per minute and within 40 minutes of recovery after the test in healthy young men with different levels of autonomic tone. Records of the chest rheoplethysmogram were recorded on a rheograph KhAI-medica standard (KhAI-medica, Kharkiv, Ukraine), a capnogram - in a lateral flow on a infrared capnograph (Datex, Finland), and the duration of R-R intervals was determined by a Polar WIND Link in the program of Polar Protrainer 5.0 (Polar Electro OY, Finland). Systolic and diastolic blood pressure were measured by Korotkov’s auscultatory method by mercury tonometer (Riester, Germany). The indicator of the normalized power of the spectrum in the range of 0.15–0.40 Hz was evaluated by 5-minute records; three groups of persons were distinguished according to its distribution at rest by the method of signal deviation, namely, sympathicotonic, normotonic and parasympathicotonic. The initial level of autonomic tone was found to impact the dynamics of СО2 level in alveolar air during hyperventilation and during recovery thereafter. Thus, PetCО2 was higher (41.3 mm Hg) in parasympathicotonic than in sympathicotonic (39.3 mm Hg) and normotonic (39.5 mm Hg) persons. During the test, R-R interval duration decreased being more expressed in normotonic persons. At the same time, the heart index was found to increase in three groups, and general peripheral resistance – to decrease mostly in normo- and parasympathicotonic persons. In addition, the reliable increase of stroke index and heart index was found in these groups. In the recovery period after hyperventilation, the decrease of tension index and ejection speed was found in normo- and, particularly, parasympathicotonic compared with sympathicotonic men and the increase of tension phase and ejection phase duration.

scholarly journals Forensic Engineering Analysis Of Motorcycle Impacts Using Rotational Mechanics And Fork/Vehicle Deformation

2012 ◽  
Vol 29 (1) ◽  
Author(s):  
Jerry S. Ogden ◽  
Kloberdanz Katrina M.
Keyword(s):  
Impact Velocity ◽  
Test Data ◽  
Impact Test ◽  
Linear Momentum ◽  
Engineering Analysis ◽  
Forensic Engineering ◽  
Ejection Speed ◽  
Rotational Mechanics

Methods Of Reconstructing Motorcycle Collisions Have Traditionally Been Limited To Speed From Skid Marks, Speeds From Scrapes Or Gouges, Speed From Rider Ejection, Speed From Linear Momentum, Or Sometimes Speed From Witness Observations. Oftentimes, The Data Necessary For Analysis Is Either Misunderstood Or Misinterpreted. This Paper Tests The Applicability Of Using Rotational Mechanics And Specific Models For Motorcycle Front Fork Deformation And Vehicle Deformation When Determining Motorcycle Impact Velocity. Additionally, The Results Of These Methods Are Statistically Tested For Significance And Reliability Against Independent Motorcycle Impact Test Data.

scholarly journals The Gaussian cannon

2017 ◽  
Vol 1 ◽  
pp. 6 ◽  
Author(s):  
Åke Andersson ◽  
Carl-Joar Karlsson ◽  
Hampus Lane
Keyword(s):  
Potential Energy ◽  
Optimal Number ◽  
Attractive Force ◽  
Firing Process ◽  
Ejection Speed ◽  
Steel Balls

This report studies different properties of a Gaussian cannon. The cannon’s firing velocity is measured for a varying number of steel balls, varying input velocity and different geometries of the cannon. By measuring the attractive force from the magnet on the balls a mapping of the potential energy for the firing process is acquired. It is found that the firing of a Gaussian cannon can be modeled as successive collisions between the magnet and its neighboring balls, and between successive balls. To reach the highest possible ejection speed with a trigger ball that is released from rest, a chained cannon should be used. The optimal number of balls on each individual cannon depends on magnetization energies and coefficients of restitution.

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