scholarly journals Vaporization, Diffusion and Combustion of Laser-Induced Individual Magnesium Microparticles in Inert and Oxidizing Atmospheres

Processes ◽  
2021 ◽  
Vol 9 (11) ◽  
pp. 2057
Author(s):  
Fan Yang ◽  
Shengji Li ◽  
Xunjie Lin ◽  
Jiankan Zhang ◽  
Heping Li ◽  
...  
Keyword(s):  
Diffusion Coefficients ◽  
High Speed ◽  
Diffusion Rate ◽  
Normal Pressure ◽  
Inert Gases ◽  
Oxide Thin Film ◽  
Pure Oxygen ◽  
High Speed Cinematography ◽  
Porous Magnesium ◽  
Combustion Behaviors

Although the gas phase combustion of metallic magnesium (Mg) has been extensively studied, the vaporization and diffusive combustion behaviors of Mg have not been well characterized. This paper proposes an investigation of the vaporization, diffusion, and combustion characteristics of individual Mg microparticles in inert and oxidizing gases by a self-built experimental setup based on laser-induced heating and microscopic high-speed cinematography. Characteristic parameters like vaporization and diffusion coefficients, diffusion ratios, flame propagation rates, etc., were obtained at high spatiotemporal resolutions (μm and tens of μs), and their differences in inert gases (argon, nitrogen) and in oxidizing gases (air, pure oxygen) were comparatively analyzed. More importantly, for the core–shell structure, during vaporization, a shock wave effect on the cracking of the porous magnesium oxide thin film shell-covered Mg core was first experimentally revealed in inert gases. In air, the combustion flame stood over the Mg microparticles, and the heterogeneous combustion reaction was controlled by the diffusion rate of oxygen in air. While in pure O2, the vapor-phase stand-off flame surrounded the Mg microparticles, and the reaction was dominated by the diffusion rate of Mg vapor. The diffusion coefficients of the Mg vapor in oxidizing gases are 1~2 orders of magnitude higher than those in inert gases. However, the diffusive ratios of condensed combustion residues in oxidizing gases are ~1/2 of those in inert gases. The morphology and the constituent contents analysis showed that argon would not dissolve into liquid Mg, while nitrogen would significantly dissolve into liquid Mg. In oxidizing gases of air or pure O2, Mg microparticles in normal pressure completely burned due to laser-induced heating.

scholarly journals Laser-Induced Ignition and Combustion of Individual Aluminum Particles Below 10 μm by Microscopic High-Speed Cinematography

Processes ◽  
2020 ◽  
Vol 8 (3) ◽  
pp. 280 ◽  
Author(s):  
Fengting Hou ◽  
Shengji Li ◽  
Yue Wang ◽  
Xuefeng Huang
Keyword(s):  
Direct Observation ◽  
High Speed ◽  
Combustion Mechanism ◽  
Aluminum Particles ◽  
Experimental Apparatus ◽  
High Speed Cinematography ◽  
Metal Aluminum ◽  
Induced Ignition ◽  
Combustion Behaviors ◽  
Ignition And Combustion

Metal aluminum has been widely used as an ingredient in propellant, gunpowder and thermite, but there is less understanding of the combustion mechanism of aluminum particles from submicron to several microns in diameter. This paper proposes to experimentally investigate the ignition and combustion characteristics of individual aluminum particles below 10 μm. A specific in situ diagnostic experimental apparatus was first designed for directly observing the ignition and combustion behaviors of individual aluminum particles, with a submicrometer spatial resolution and a temporal resolution of tens of microseconds. Direct observation through microscopic high-speed cinematography demonstrated that, when heated by a continuous laser, individual aluminum particles thermally expanded, followed by shell rupture; the molten aluminum core overflowed and evaporated, leading to ignition and combustion. Further results showed that, when the laser power densities were gradually increased (5.88, 7.56 and 8.81 × 105 W/cm2), the durations of thermal expansion, melting and evaporation were shortened. The required time for the aluminum particles to expand to 150% of their initial diameter was shortened (34 s, 0.34 s and 0.0125 s, respectively). This study will be beneficial to further extend the investigation of other individual metal particles and reveal their combustion mechanism by direct observation.

Effect of Macropore Structure on Desorption Diffusion Performance of N-Pentane on 5A Zeolite

2013 ◽  
Vol 634-638 ◽  
pp. 731-735 ◽  
Author(s):  
Lu Shi ◽  
Zong Jian Liu ◽  
Qun Cui ◽  
Hai Yan Wang ◽  
Hu Qing Yao
Keyword(s):  
Diffusion Coefficients ◽  
Diffusion Rate ◽  
Low Pressure ◽  
Fast Diffusion ◽  
Desorption Rate ◽  
Macropore Structure ◽  
5A Zeolite ◽  
Desorption Equilibrium

Desorption rate curves of n-pentane on 5A zeolites at 418 K and 10-0.03 kPa were determined, and the effects of different macropore structure on desorption performance were analyzed. Results show that macropore distribution of 5A-1 concentrates in 0.25-1.25 μm, while that of 5A-2 ranges from mesopore category to 0.3 μm, but 5A-3 contains both pores of 0.01-0.1 μm and 0.2-2 μm inside, reflecting a broadest distribution; 5A-3, 5A-1 and 5A-2 reach desorption equilibrium after 1100 s, 1400 s and 2000 s respectively at 0.03 kPa, indicating that abundant macropores make n-pentane fastest desorbed from 5A-3, but this advantage gradually disappears with the increasing pressure; the effective desorption diffusion coefficients of n-pentane on 5A-1, 5A-2 and 5A-3 are 4.2×10-15-2.2×10-14 m2/s, 2.0×10-15-2.3×10-14 m2/s, 7.4×10-15-2.4×10-14 m2/s respectively, suggesting that plenty macropores make the diffusivity less affected by the changes of pressure, which can guarantee a fast diffusion rate of n-pentane even at low pressure.

A PROCEDURE TO DETERMINE THE SEGREGATION PARAMETERS IN TERNARY SYSTEMS FROM EXPERIMENTAL DATA OF A LINEAR TEMPERATURE RUN

2007 ◽  
Vol 14 (04) ◽  
pp. 681-685
Author(s):  
W. D. ROOS ◽  
J. K. O. ASANTE
Keyword(s):  
High Temperature ◽  
Temperature Region ◽  
Diffusion Coefficients ◽  
High Speed ◽  
Ternary Systems ◽  
Equilibrium Temperature ◽  
Rate Equations ◽  
Interaction Coefficients ◽  
Linear Temperature ◽  
Good Set

Profiles of surface concentrations as a function of temperature, where the temperature is increased at a constant rate, contain the necessary information to extract segregation parameters. A model using rate equations can be used to simulate these profiles. Even on a high-speed computer, solving these equations can take hours. For ternary and higher component alloys the fit parameters are at least nine and finding the best fit manually can extend the search to days. Theoretical segregation and diffusion models show two temperature regions of interest. In the low-temperature region, representing the kinetics of segregation, the diffusion coefficients of the species dominate the flux of atoms to the surface, and in the high-temperature region the surface concentrations are independent of the diffusion coefficients. In the high-temperature equilibrium region the surface concentrations are determined only by the segregation energies and interaction coefficients. A procedure is presented that can find a good set of segregation parameters within seconds. The sensitivity of selecting the kinetics, as well as the equilibrium temperature regions will be demonstrated. The procedure is used to extract the segregation parameters for a Cu (111) 0.13 at% Sn 0.18 at% Sb system.

New findings on life history traits of Xenos peckii (Strepsiptera: Xenidae)

2014 ◽  
Vol 146 (5) ◽  
pp. 514-527 ◽  
Author(s):  
M. Hrabar ◽  
A. Danci ◽  
S. McCann ◽  
P.W. Schaefer ◽  
G. Gries
Keyword(s):  
Life History ◽  
High Speed ◽  
Life History Traits ◽  
Suture Line ◽  
Paper Wasp ◽  
Anterior Portion ◽  
New Findings ◽  
High Speed Cinematography ◽  
Normal Speed ◽  
Wasp Nests

AbstractWe studied life history traits of Xenos peckii Kirby (Strepsiptera: Xenidae), a little-known parasite of the paper wasp Polistes fuscatus (Fabricus) (Hymenoptera: Vespidae) in North America. We field-collected 24 wasp nests in early July 2012, isolated parasitised wasps, tracked life history events of X. peckii, and recorded such behaviour as emergence of males and mating by normal-speed and high-speed cinematography. To emerge, males first cut the puparium with their mandibles along an ecdysial suture line, and then push aside the pupal cap during emergence. The endoparasitic females engage in active calling (pheromone release) behaviour by slowly inflating their cephalothorax, and then extruding it even farther out of, and tilting it away from, the host wasp abdomen. Seasonal and diel (afternoon) emergence periods of males coincide with seasonal and diel receptivity and calling periods of females. Males approach calling females in a swaying flight with smooth turns. They typically land on the anterior portion of the host wasp's abdomen, and then step backward until they make contact with the cephalothorax of the female. As soon as their mesothoracic legs contact the female's cephalothorax, they curl around it, and the male initiates mating. Thereafter, the female fully retreats and never re-mates.

Angular Momentum Requirements of the Twisting and Nontwisting Forward 1 1/2 Somersault Dive

1987 ◽  
Vol 3 (1) ◽  
pp. 47-62 ◽  
Author(s):  
Ross H. Sanders ◽  
Barry D. Wilson
Keyword(s):  
Angular Momentum ◽  
High Speed ◽  
Center Of Gravity ◽  
Transverse Axis ◽  
Free Position ◽  
High Speed Cinematography ◽  
The Difference ◽  
Hip Flexion ◽  
Commonwealth Games

This study investigated the in-flight rotation of elite 3m springboard divers by determining the angular momentum requirement about the transverse axis through the divers center of gravity (somersault axis) required to perform a forward 1 1/2 somersault with and without twist. Three elite male divers competing in the 1982 Commonwealth Games were filmed using high-speed cinematography while performing the forward 1 1/2 somersault in the pike position and the forward 1 1/2 somersault with one twist in a free position. The film was digitized to provide a kinematic description of each dive. An inclined axis technique appeared to be the predominant means of producing twist after takeoff from the board. The angular momentum about the somersault axis after takeoff was greater for the forward 1 1/2 somersault with twist than the forward 1 1/2 somersault without twist for all three divers. The difference in angular momentum between the two dives of each diver ranged from 6% to 19%. The most observable difference between the dives during the preflight phases was the degree of hip flexion at takeoff. There was more hip flexion at takeoff in 5132D than 103B for all three divers. This difference ranged from 9° to 18° (mean = 14°).

Kinematics of Tongue Projection in Chamaeleo Oustaleti

1991 ◽  
Vol 159 (1) ◽  
pp. 109-133 ◽  
Author(s):  
PETER C. WAINWRIGHT ◽  
DAVID M. KRAKLAU ◽  
ALBERT F. BENNETT
Keyword(s):  
High Speed ◽  
Prey Capture ◽  
Maximum Velocity ◽  
Head Movements ◽  
Florida State University ◽  
State University ◽  
Maximum Acceleration ◽  
Related Family ◽  
High Speed Cinematography ◽  
Tongue Movements

The kinematics of prey capture by the chamaeleonid lizard Chamaeleo oustaleti were studied using high-speed cinematography. Three feeding sequences from each of two individuals were analyzed for strike distances of 20 and 35 cm, at 30°C. Ten distances and angles were measured from sequential frames beginning approximately 0.5 s prior to tongue projection and continuing for about 1.0 s. Sixteen additional variables, documenting maximum excursions and the timing of events, were calculated from the kinematic profiles. Quantified descriptions of head, hyoid and tongue movements are presented. Previously unrecognized rapid protraction of the hyobranchial skeleton simultaneously with the onset of tongue projection was documented and it is proposed that this assists the accelerator muscle in powering tongue projection. Acceleration of the tongue occurred in about 20ms, reaching a maximum acceleration of 486 m s−2 and maximum velocity of 5.8m s−1 in 35 cm strikes. Deceleration of the tongue usually began within 5 ms before prey contract and the direction of tongue movement was reversed within 10 ms of prey contact. Retraction of the tongue, caused by shortening of the retractor muscles, reached a maximum velocity of 2.99 ms−1 and was complete 330 ms after prey contact. Projection distance influences many aspects of prey capture kinematics, particularly projection time, tongue retraction time and the extent of gape and head movements during tongue retraction, all of which are smaller in shorter feedings. Though several features of the chameleon strike have apparently been retained from lizards not capable of ballistic tongue projection, key differences are documented. Unlike members of a related family, the Agamidae, C. oustaleti uses no body lunge during prey capture, exhibits gape reduction during tongue projection and strongly depresses the head and jaws during tongue retraction. Note: Present address: Department of Biological Sciences, Florida State University, Tallahassee, FL 32306, USA.

Kinematic analysis of tongue movements during chemosensory behaviour in the European green lizard, Lacerta viridis (Reptilia: Lacertidae)

1992 ◽  
Vol 70 (10) ◽  
pp. 1886-1896 ◽  
Author(s):  
Véronique Goosse ◽  
Vincent L. Bels
Keyword(s):  
High Speed ◽  
Prey Capture ◽  
Principal Component ◽  
Upward Movement ◽  
High Speed Cinematography ◽  
Tongue Movements ◽  
Lacerta Viridis ◽  
Tongue Flicking ◽  
Stationary Interval ◽  
Tongue Displacement

High-speed cinematography (100 frames/s) was used to allow quantitative analysis of the kinematic profiles of tongue and jaw displacements during chemosensory activities in the scleroglossan lizard Lacerta viridis. The types of tongue flicking were simple downward extensions (SDE), single oscillations (SOC), and submultiple oscillations (SMOC) of the tongue out of the mouth. The SMOC type involves a downward or upward movement of the tongue performed before a typical oscillation and it is therefore suggested that this is an intermediate category of flick between the typical SOC and MOC of lizards. Closing and opening of the mouth in SDE, SOC, and SMOC cycles may or may not be separated by a stationary stage during which the jaws are held open at a constant gape. The duration of this stationary interval increases from SDE to SMOC. Gape cycles do not show any division into slow and fast stages. The gape is produced largely by depression of the lower jaw; the upper jaw is slightly elevated by protrusion of the tongue. Patterns of correlation of kinematic variables depicting jaw and tongue movements differed between SDE, SOC, and SMOC. A principal component analysis shows that the three flick types overlap in a multivariate space constructed from the kinematic variables depicting jaw and tongue displacements. Overlap between SOC and SMOC categories is greater than that between SOC, SMOC, and SDE categories. The kinematic patterns of tongue displacement during SMOC in Lacerta viridis show similarities with those of MOC in other lizards and in snakes. Kinematically, the pattern of jaw and tongue displacements of Lacerta viridis during chemosensory activities shows similarities with those that occur during drinking and prey capture.

scholarly journals THE MECHANISM OF THE NEPHRIDIAL APPARATUS OF PARAMECIUM MUL TIMICRONUCLEATUM

1968 ◽  
Vol 37 (1) ◽  
pp. 139-146 ◽  
Author(s):  
Alan E. Organ ◽  
Eugene C. Bovee ◽  
Theodore L. Jahn ◽  
Duncan Wigg ◽  
James R. Fonseca
Keyword(s):  
Electron Microscopy ◽  
Excretory Pore ◽  
High Speed ◽  
Cell Membranes ◽  
Recent Analysis ◽  
Opposite Wall ◽  
Active Contraction ◽  
High Speed Cinematography ◽  
Excretory Canal

Recent analysis of the mechanism of the nephridial apparatus of Paramecium multimicronucleatum by high-speed cinematography (300 fps at x 250) confirms the observations by electron microscopy (Schneider, 1960) that once the pore is opened, the vesicle is invaginated by adjacent cytoplasm and is emptied by collapsing under pressure from that cytoplasm, aided perhaps by pressure of the fibrils which anchor the ampullae to the excretory canal. There is no indication of active contraction of the vesicle or its membrane. There is no permanent pore to the vesicle. The vesicle is closed by a sealing of the ruptured membrane where it is in contact with the pellicular excretory canal. At onset of expulsion of vesicular fluid the membrane across the basal opening of the excretory canal is ripped along one semicircular portion of the excretory pore and is driven up against the opposite wall as a flap while the water rushes out. A constriction of the vesicular and cell membranes at the base of the excretory canal reseals the opening.

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