scholarly journals Combustion of a plane hydrogen microjet at subsonic and supersonic speeds

2019 ◽  
Vol 485 (3) ◽  
pp. 300-305
Author(s):  
V. V. Kozlov ◽  
G. R. Grek ◽  
Yu. A. Litvinenko ◽  
A. G. Shmakov ◽  
V. V. Vikhorev
Keyword(s):  
Nozzle Exit ◽  
Experimental Studies ◽  
Supersonic Combustion ◽  
Diffusion Combustion ◽  
Flame Region ◽  
First Time

In this paper, we presented the results of experimental studies of the diffusion combustion of a plain hydrogen microjet flowing from a slit micronozzle at subsonic and supersonic speeds. For the first time, four scenarios of diffusion combustion of a plain hydrogen microjet including supersonic combustion in the presence of supersonic cells in both air and hydrogen are presented. The stabilization of the subsonic combustion of a hydrogen microjet was established to be due to the presence of a «bottleneck flame region» while the stabilization of the supersonic combustion of a microjet was found to be associated with the presence of supersonic cells. The observed hyster­esis of diffusion combustion of a plain hydrogen microjet depends on both the method of igniting the microjet (near or far from the nozzle exit) and the direction of change in the rate of its outflow (growth or reduction).

scholarly journals Air Round Microjet Interaction with Coaxial Hydrogen Jet at It Combustion for Supersonic Speed Jets Efflux

2019 ◽  
Vol 14 (3) ◽  
pp. 53-63
Author(s):  
V. V. Kozlov ◽  
G. R. Grek ◽  
M. V. Litvinenko ◽  
Yu. A. Litvinenko ◽  
A. S. Tambovzev ◽  
...  
Keyword(s):  
Nozzle Exit ◽  
Acoustic Noise ◽  
Turbulent Flame ◽  
Experimental Studies ◽  
Supersonic Combustion ◽  
Small Scale ◽  
Diffusion Combustion ◽  
Supersonic Speed ◽  
Combustion Region ◽  
Flame Region

Results of experimental studies of the round air microjet interaction with a coaxial hydrogen jet at its combustion for supersonic speed jets efflux are presented in this work. It is revealed that combustion of the coaxial hydrogen jet with growth of its speed efflux is accompanied by all scenarios, observed at study of the round and plane hydrogen microjets diffusion combustion. However, “bottleneck flame region” undergoes considerable geometrical deformations because of specifics of a flame of a coaxial jet. It is shown that “bottleneck flame region” is transformed from Y-shaped to spherical shape in the activity of growth of a coaxial jet speed efflux. It is found that a round air microjet interaction with a coaxial hydrogen jet at its combustion is accompanied by several new phenomena: existence of cone-shaped area a coaxial jet combustion near a nozzle exit; existence of small-scale supersonic cells on a resultant flame; absence of the hydrogen combustion efflux from combustion region of a coaxial jet near nozzle exit; flame-out from combustion region of a coaxial jet near nozzle exit that leads to hydrogen ignition downstream, its intensive combustion and sharp acoustic noise occurrence; existence of a turbulent flame, to its separation from a nozzle exit and transition to supersonic combustion of a resultant jet.

scholarly journals Features of the Round Hydrogen Microjet Combustion in a Coaxial Jet of the Air and Nanopouder Mixture

2019 ◽  
Vol 14 (2) ◽  
pp. 35-45
Author(s):  
V. V. Kozlov ◽  
G. R. Grek ◽  
M. V. Litvinenko ◽  
Yu. A. Litvinenko ◽  
A. S. Tambovtsev ◽  
...  
Keyword(s):  
Nozzle Exit ◽  
Experimental Studies ◽  
The Other ◽  
Diffusion Combustion ◽  
Other Hand ◽  
Coaxial Nozzle ◽  
Flame Region ◽  
Efflux Velocity

Results of the experimental studies of a round hydrogen microjet combustion in a coaxinal jet of air and SiO2 nanopouder mixture efflux from a slot-hole (multinozzle) coaxial nozzle at subsonic and supersonic efflux velocity are presented. It is shown that scenarios of a hydrogen microjet combustion in a coaxinal jet of air and nanopouder mixture are similar to scenarios of diffusion combustion of a hydrogen microjet at subsonic and supersonic efflux velocity. Existence of “bottleneck flame region” is revealed at subsonic and a flame separation from a nozzle exit at supersonic efflux velocity. It is found that with efflux velocity growth of jets it is possible to observe intensification of the luminescence of the flame at the boundary between the jet of hydrogen and air / nanopowder mixture and existence of «bottleneck flame region» as in a laminar coaxial jet and in a flame of a hydrogen microjet combustion. On the other hand, it is possible to observe actually disappearance of the «bottleneck flame region» at approach to transonic efflux velocity.

scholarly journals Features of the Round Hydrogen Microjet Combustion in a Coaxial Air Jet

2019 ◽  
Vol 14 (2) ◽  
pp. 21-34
Author(s):  
V. V. Kozlov ◽  
G. R. Grek ◽  
M. M. Katasonov ◽  
M. V. Litvinenko ◽  
Yu. A. Litvinenko ◽  
...  
Keyword(s):  
Nozzle Exit ◽  
Experimental Studies ◽  
Spherical Shape ◽  
Supersonic Combustion ◽  
Cylindrical Shape ◽  
Air Jet ◽  
Flame Region ◽  
Efflux Velocity

Results of experimental studies of features of the round hydrogen microjet combustion in a coaxial air jet are presented in this work. It is shown that the combustion scenario is connected with existence of the «bottleneck flame region». This fact correlates with the similar scenarios of the diffusion hydrogen microjet combustion at subsonic efflux velocity investigated by us earlier. It is revealed that the spherical shape of the “bottleneck flame region” is transformed to a cylindrical shape. It is found that the round hydrogen microjet combustion in a coaxial air jet at supersonic efflux velocity is accompanied by existence of supersonic cells both in a hydrogen microjet and in a wake of coaxial air jet. Round hydrogen microjet supersonic combustion in a coaxial air jet is connected with a flame separation from a nozzle exit.

Features Of The Diffusion Combustion Of Hydrogen Microjet At Various Spatial Orientation Of The Nozzle Exit

2015 ◽  
Vol 10 (4) ◽  
pp. 60-76
Author(s):  
Genrich Grek ◽  
Viktor Kozlov ◽  
Oleg Korobeinichev ◽  
Yuriy Litvinenko ◽  
Andrey Shmakov
Keyword(s):  
Nozzle Exit ◽  
Spatial Orientation ◽  
Velocity Vector ◽  
Experimental Studies ◽  
Diffusion Combustion ◽  
Jet Velocity ◽  
Basic Characteristics ◽  
Vector Orientation ◽  
The Given ◽  
Combustion Of Hydrogen

The purpose of the given work will consist in the experimental studies of features diffusion combustion of a hydrogen round microjet depending on spatial orientation of the nozzle exit. It is revealed, that a hydrogen round microjet at diffusion combustion in conditions of a jet velocity vector orientation towards terrestrial gravitation vector «g» (opposite or perpendicular) the basic characteristics of the flame evolution depending on a jet velocity are practically coincided. To these characteristics concern such as ranges of the «bottleneck» flame area presence, flame detachment at presence of the «bottleneck» flame area, presence of the «bottleneck» flame area, but absence of a turbulent jet combustion and finally ending of the microjet combustion. On the contrary, in situation of the hydrogen round microjet diffusion combustion in conditions of a jet velocity vector orientation towards terrestrial gravitation vector «g» (orientability – like) the basic characteristics of the flame evolution depending on a jet velocity are sharply differed from two previous cases. The range of existence of the «bottleneck» flame area is reduced, flame detachment occurs in absence of the «bottleneck» flame area and finally ending of the microjet combustion occurs at the much greater jet velocity.

Influence Of Initial Conditions At The Micro Nozzle Exit On Hydrogen Diffusion Combustion

2016 ◽  
Vol 11 (3) ◽  
pp. 34-45
Author(s):  
Viktor Kozlov ◽  
Genrich Grek ◽  
Oleg Korobeinichev ◽  
Yuriy Litvinenko ◽  
Andrey Shmakov
Keyword(s):  
Velocity Profile ◽  
Nozzle Exit ◽  
Hydrogen Diffusion ◽  
Initial Conditions ◽  
Diffusion Combustion ◽  
Mean Velocity ◽  
Micro Nozzle ◽  
Flame Region ◽  
Region Size ◽  
Efflux Velocity

The purpose of the given work will consist in an experimental study of influence of initial conditions at the micro nozzle exit on hydrogen diffusion combustion. It is shown, that the mean velocity profile and presence/absence of a heatcapacious material at the nozzle exit play an essential role on a flame structure and process of a round hydrogen microjet combustion. Velocity ranges of existence of a round hydrogen microjet diffusion combustion, flame separation and «bottleneck flame» region for a case of a top – hat mean velocity profile at the nozzle and two cases of a parabolic mean velocity profile with presence/absence of a heatcapacious material at the nozzle exit are found. Dependences of the «bottleneck flame» region size from a hydrogen microjet efflux velocity for case of a top – hat mean velocity profile at the nozzle and two cases of a parabolic mean velocity profile with presence/absence of a heatcapacious material at the nozzle exit are shown. Decrements of reduction of the «bottleneck flame» region size with growth of the hydrogen microjet efflux velocity for three situations of changes of initial conditions at the nozzle exit are determined.

scholarly journals What voiced obstruents symbolically represent in Japanese: evidence from the Pokémon universe

2021 ◽  
Vol 37 (1) ◽  
pp. 3-24
Author(s):  
Shigeto Kawahara ◽  
Gakuji Kumagai
Keyword(s):  
Experimental Studies ◽  
Sound Symbolism ◽  
Visual Images ◽  
General Issue ◽  
First Time

Abstract Kawahara, Noto, and Kumagai (2018b) found that within the corpus of existing Pokémon names, the number of voiced obstruents in the characters’ names correlates positively with their weight, height, evolution levels and attack values. While later experimental studies to some extent confirmed the productivity of these sound symbolic relationships (e.g. Kawahara and Kumagai 2019a), they are limited, due to the fact that the visual images presented to the participants primarily differed with regard to evolution levels. The current experiments thus for the first time directly explored how each of these semantic dimensions—weight, height, evolution levels, and attack values—correlates with the number of voiced obstruents in nonce names. The results of two judgment experiments show that all of these parameters indeed correlate positively with the number of voiced obstruents in the names. Overall, the results show that a particular class of sounds—in our case, a set of voiced obstruents—can signal different semantic meanings within a single language, supporting the pluripotentiality of sound symbolism (Winter, Pérez-Sobrino, and Brown 2019). We also address another general issue that has been under-explored in the literature on sound symbolism; namely, its cumulative nature. In both of the experiments, we observe that two voiced obstruents evoke stronger images than one voiced obstruent, instantiating what is known as the counting cumulativity effect (Jäger and Rosenbach 2006).

scholarly journals Moral psychology of sex robots: An experimental study − how pathogen disgust is associated with interhuman sex but not interandroid sex

2020 ◽  
Vol 11 (1) ◽  
pp. 233-249 ◽  
Author(s):  
Mika Koverola ◽  
Marianna Drosinou ◽  
Jussi Palomäki ◽  
Juho Halonen ◽  
Anton Kunnari ◽  
...  
Keyword(s):  
Science Fiction ◽  
Experimental Studies ◽  
Sex Worker ◽  
Interest In Science ◽  
Sex Robots ◽  
Monogamous Relationship ◽  
Attitudes Toward Sex ◽  
First Time ◽  
And Robotics ◽  
Shed Light

AbstractThe idea of sex with robots seems to fascinate the general public, raising both enthusiasm and revulsion. We ran two experimental studies (Ns = 172 and 260) where we compared people’s reactions to variants of stories about a person visiting a bordello. Our results show that paying for the services of a sex robot is condemned less harshly than paying for the services of a human sex worker, especially if the payer is married. We have for the first time experimentally confirmed that people are somewhat unsure about whether using a sex robot while in a committed monogamous relationship should be considered as infidelity. We also shed light on the psychological factors influencing attitudes toward sex robots, including disgust sensitivity and interest in science fiction. Our results indicate that sex with a robot is indeed genuinely considered as sex, and a sex robot is genuinely seen as a robot; thus, we show that standard research methods on sexuality and robotics are also applicable in research on sex robotics.

scholarly journals An Approach to Risk Assessment and Threat Prediction for Complex Object Security Based on a Predicative Self-Configuring Neural System

Symmetry ◽  
2022 ◽  
Vol 14 (1) ◽  
pp. 102
Author(s):  
Nikolai Vladimirovich Korneev ◽  
Julia Vasilievna Korneeva ◽  
Stasis Petrasovich Yurkevichyus ◽  
Gennady Ivanovich Bakhturin
Keyword(s):  
Neural Network ◽  
Risk Assessment ◽  
Fundamental Problem ◽  
Experimental Studies ◽  
Neural System ◽  
Assessment System ◽  
Classification Model ◽  
Complex Object ◽  
Assessment Problems ◽  
First Time

We identified a set of methods for solving risk assessment problems by forecasting an incident of complex object security based on incident monitoring. The solving problem approach includes the following steps: building and training a classification model using the C4.5 algorithm, a decision tree creation, risk assessment system development, and incident prediction. The last system is a predicative self-configuring neural system that includes a SCNN (self-configuring neural network), an RNN (recurrent neural network), and a predicative model that allows for determining the risk and forecasting the probability of an incident for an object. We proposed and developed: a mathematical model of a neural system; a SCNN architecture, where, for the first time, the fundamental problem of teaching a perceptron SCNN was solved without a teacher by adapting thresholds of activation functions of RNN neurons and a special learning algorithm; and a predicative model that includes a fuzzy output system with a membership function of current incidents of the considered object, which belongs to three fuzzy sets, namely “low risk”, “medium risk”, and “high risk”. For the first time, we gave the definition of the base class of an object’s prediction and SCNN, and the fundamental problem of teaching a perceptron SCNN was solved without a teacher. We propose an approach to neural system implementation for multiple incidents of complex object security. The results of experimental studies of the forecasting error at the level of 2.41% were obtained.

scholarly journals Investigation of the Flow In Cold Condition at the Exit of a Supersonic Combustor Test Bench

2020 ◽  
Author(s):  
Jefte da Silva Guimarães ◽  
Valéria Serrano Faillace Oliveira Leite ◽  
Dermeval Carinhana Junior ◽  
Marco Antônio Sala Minucci
Keyword(s):  
Nozzle Exit ◽  
Test Bench ◽  
Supersonic Combustion ◽  
Flow Conditions ◽  
Circular Section ◽  
Cold Flow ◽  
Ground Test ◽  
Cold Condition ◽  
Transition Piece ◽  
Generator Unit

For studies of hypersonic flows and supersonic combustion in ground test facilities, three devices can be used as ram accelerators, shock tunnels and supersonic combustor test benches. These devices can reproduce, on the ground, similar conditions to those in real flight at a certain altitude and speed. In the case of the supersonic combustor test bench (SCTB), it simulates the same flow conditions inside the combustor of a scramjet. The SCTB consists basically of a combustion chamber or vitiated air generator unit, where the air is heated, and a nozzle, where the air is accelerated to the desired test speed. The supersonic combustor to be tested is directly coupled to the nozzle exit of the SCTB. Ultimately, it was necessary to use a transition piece to connect the nozzle to the combustor to be tested, because the nozzle exit has a circular section and the combustor entrance has a rectangular one. This work aims to present the process of characterizing the cold flow along the SCTB of the Institute for Advanced Studies (IEAv) using the schlieren technique. The interference of the transition piece in obtaining the required flow conditions at the exit of the SCTB or the entrance of the combustor was mainly evaluated.

scholarly journals Blastocystis ratti Contains Cysteine Proteases That Mediate Interleukin-8 Response from Human Intestinal Epithelial Cells in an NF-κB-Dependent Manner

2007 ◽  
Vol 7 (3) ◽  
pp. 435-443 ◽  
Author(s):  
Manoj K. Puthia ◽  
Jia Lu ◽  
Kevin S. W. Tan
Keyword(s):  
Gene Expression ◽  
Epithelial Cells ◽  
Intestinal Inflammation ◽  
Experimental Studies ◽  
Cysteine Proteases ◽  
Interleukin 8 ◽  
Dependent Manner ◽  
Public Health Importance ◽  
Wide Range ◽  
First Time

ABSTRACT Blastocystis is a ubiquitous enteric protozoan found in the intestinal tracts of humans and a wide range of animals. Evidence accumulated over the last decade suggests association of Blastocystis with gastrointestinal disorders involving diarrhea, abdominal pain, constipation, nausea, and fatigue. Clinical and experimental studies have associated Blastocystis with intestinal inflammation, and it has been shown that Blastocystis has potential to modulate the host immune response. Blastocystis is also reported to be an opportunistic pathogen in immunosuppressed patients, especially those suffering from AIDS. However, nothing is known about the parasitic virulence factors and early events following host-parasite interactions. In the present study, we investigated the molecular mechanism by which Blastocystis activates interleukin-8 (IL-8) gene expression in human colonic epithelial T84 cells. We demonstrate for the first time that cysteine proteases of Blastocystis ratti WR1, a zoonotic isolate, can activate IL-8 gene expression in human colonic epithelial cells. Furthermore, we show that NF-κB activation is involved in the production of IL-8. In addition, our findings show that treatment with the antiprotozoal drug metronidazole can avert IL-8 production induced by B. ratti WR1. We also show for the first time that the central vacuole of Blastocystis may function as a reservoir for cysteine proteases. Our findings will contribute to an understanding of the pathobiology of a poorly studied parasite whose public health importance is increasingly recognized.

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