Dependence of the critical energy of detonation initiation by impact on the mass of the impacting plate

1983 ◽  
Vol 19 (2) ◽  
pp. 237-239
Author(s):  
M. Ya. Vasil'ev
1999 ◽  
Author(s):  
Ed O'Keefe ◽  
Matt Berge

2017 ◽  
Vol 68 (9) ◽  
pp. 2189-2195
Author(s):  
Valeriu V. Jinescu ◽  
Simona Eugenia Manea ◽  
George Jinescu ◽  
Vali Ifigenia Nicolof

Following the activities developed in a nuclear facility result gaseous and liquid radioactive effluents and radioactive solid waste. All these waste contain radioactive isotopes which are potentially pollutants for the environment. In the same time chemicals are, also, pollutants. According to the legislation, discharging of chemicals and radioactive liquid and gaseous effluents into the environment, should meet the requirements of the unrestricted discharge. However, what happens when several pollutants superpose: only chemical pollutants, or only radioactive pollutants, or chemical and radioactive pollutants? Such problems have been solved in this paper on the basis of the principle of critical energy.


Author(s):  
Melissa Anne-Marie Curley

For a thousand years, Japanese Buddhists cultivated vivid images of utopia in the form of the Western Paradise, but in the modern period, this utopianism became troublesome. Shinshū modernizers reinvented the Pure Land: some molded it into something the nation-state could tolerate; others used it to secure their own autonomy. Their reinterpretations encouraged new engagements with the tradition; during the war years, as the Japanese state bore down upon its citizens, thinkers with no obvious connection to Shinshū seized upon the twinned images of Shinran in exile and Amida’s Pure Land. For economist Kawakami Hajime, the Pure Land represented an inner realm of peace, the discovery of which allowed him to remain committed to Marxism through years in prison and forced seclusion. For philosopher Miki Kiyoshi, it represented the proletariat’s historical mission of liberating humanity, making Shinshū proof positive of the possibility of a proletarian religion. For historian Ienaga Saburō, it represented sheer negation of this world, grounding Shinran’s confrontation with society; Ienaga himself sought to uphold this legacy of resistance, rallying against a state that failed to live up to its ideals. These radical readings reveal that the critical energy of medieval Pure Land has not been exhausted.


Shock Waves ◽  
2021 ◽  
Author(s):  
S. Bengoechea ◽  
J. Reiss ◽  
M. Lemke ◽  
J. Sesterhenn

AbstractAn optimisation study of a shock-wave-focusing geometry is presented in this work. The configuration serves as a reliable and deterministic detonation initiator in a pulsed detonation engine. The combustion chamber consists of a circular pipe with one convergent–divergent axisymmetric nozzle, acting as a focusing device for an incoming shock wave. Geometrical changes are proposed to reduce the minimum shock wave strength necessary for a successful detonation initiation. For that purpose, the adjoint approach is applied. The sensitivity of the initiation to flow variations delivered by this method is used to reshape the obstacle’s form. The thermodynamics is described by a higher-order temperature-dependent polynomial, avoiding the large errors of the constant adiabatic exponent assumption. The chemical reaction of stoichiometric premixed hydrogen-air is modelled by means of a one-step kinetics with a variable pre-exponential factor. This factor is adapted to reproduce the induction time of a complex kinetics model. The optimisation results in a 5% decrease of the incident shock wave threshold for the successful detonation initiation.


Author(s):  
Yuting Luo ◽  
Zhiyuan Zhang ◽  
Fengning Yang ◽  
Jiong Li ◽  
Zhibo Liu ◽  
...  

Large-scale production of green hydrogen by electrochemical water splitting is considered as a promising technology to address critical energy challenges caused by the extensive use of fossil fuels. Although nonprecious...


2020 ◽  
Vol 12 ◽  
pp. 175682772092171
Author(s):  
Fabian E Habicht ◽  
Fatma C Yücel ◽  
Joshua AT Gray ◽  
Christian O Paschereit

This work contains experimental investigations on the correlation of the detonation initiation process via a shock-focusing device with various initial pressures and mass flow rates. A pulse detonation combustor is operated with stoichiometric hydrogen--air--oxygen mixtures in single cycle operation. A rotationally symmetric shock-focusing geometry evokes the onset of a detonation by the focusing of the reflected leading shock wave, while a blockage plate at the rear end of the test rig is applied to induce an elevated initial pressure. The results show that the reactivity has a major influence on the success rate of detonation initiation. However, measurements with different blockage plates suggest that the mass flow rate has to be considered as well when predicting the success rate. Three main statements can be drawn from the results. (1) An increase in the mean flow velocity induces higher velocity fluctuations which result in a stronger leading shock ahead of the accelerating deflagration front. (2) An increase in the initial static pressure reduces the critical shock strength that must be exceeded to ensure successful detonation initiation by shock focusing. (3) Since the initial pressure is directly linked to the mass flow rate, these contrary trends can cancel each other out, which could be observed for 40% vol. of oxygen in the oxidizer. High-speed images were taken, which confirm that the detonation is initiated in the center of the converging--diverging nozzle due to focusing of the leading shock.


Materials ◽  
2018 ◽  
Vol 11 (12) ◽  
pp. 2552 ◽  
Author(s):  
Uwe Gohs ◽  
Michael Mueller ◽  
Carsten Zschech ◽  
Serge Zhandarov

Continuous glass fiber-reinforced polypropylene composites produced by using hybrid yarns show reduced fiber-to-matrix adhesion in comparison to their thermosetting counterparts. Their consolidation involves no curing, and the chemical reactions are limited to the glass fiber surface, the silane coupling agent, and the maleic anhydride-grafted polypropylene. This paper investigates the impact of electron beam crosslinkable toughened polypropylene, alkylene-functionalized single glass fibers, and electron-induced grafting and crosslinking on the local interfacial shear strength and critical energy release rate in single glass fiber polypropylene model microcomposites. A systematic comparison of non-, amino-, alkyl-, and alkylene-functionalized single fibers in virgin, crosslinkable toughened and electron beam crosslinked toughened polypropylene was done in order to study their influence on the local interfacial strength parameters. In comparison to amino-functionalized single glass fibers in polypropylene/maleic anhydride-grafted polypropylene, an enhanced local interfacial shear strength (+20%) and critical energy release rate (+80%) were observed for alkylene-functionalized single glass fibers in electron beam crosslinked toughened polypropylene.


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