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This paper presents a numerical study of the effect of burnout on the ignition delay of a typical thermoplastic polymer (polymethylmethacrylate) by a metal particle heated to a high temperature. The initial temperature of the power source was varied from 960-1150 K. Three ignition modes of the polymer are distinguished according to the temperature of the heat source, ignition delay, and the position of the ignition zone in the vicinity of the hot particle. It is found that under local heating conditions, the burnout of the heated area of the surface layer affects insignificantly (by less than 5%) the increase in the basic characteristics of the process - the ignition delay. At the time of initiation of the combustion, the degree of thermal degradation of the polymer (degree of conversion) does not reach even 15% in the section corresponding to the maximum heat flux from the heat source. It is shown that the ignition delay increases more significantly when accounting for the temperature dependence of the thermal properties of polymethylmethacrylate than when accounting for the burnout factor. The induction period is increased by 15- 25% due to an increase in the polymer storage capacity and heat transfer rate from the heated the area of the surface layer deeper into the material.

Multiwave regimes of continuous spin detonation in syngas-air mixtures in a flow-type annular cylindrical combustor 503 mm in diameter are obtained. Experiments are performed for mixtures of carbon oxide and hydrogen with the ratio of the components equal to 1/3, 1/2, or 1/1. The varied parameters are the flow rates of air and syngas, the ratio of these flow rates, and the combustor length. Scalability of the continuous spin detonation process is demonstrated: at identical values of the specific flow rate of air and the combustor expansion ratio, the number of transverse detonation waves increases with increasing combustor diameter. In the examined ranges of combustor lengths and specific flow rates of air, the frequency of these waves is independent of the combustor length, except for narrow regions where the number of waves (and, correspondingly, the flow regime) changes. The structures of transverse detonation waves in regular regimes are almost identical for all examined syngas compositions. It is shown that detonation can be initiated by a jet of combustion products. The minimum diameters of the detonation chamber for different flow rates of the mixture are estimated.

A VISAR technique was used to study the structure of the reaction region in PETN for various initial densities and dispersion of samples. The flow in the pressed charges corresponds to the classical denotation model. In the case of bulk density, the properties corresponding to an explosive combustion model are determined. In the vicinity of the initial density of 1.7 g/cm³, a kink is found on the curve showing detonation rate versus density, and the shock-wave initiation of PETN above and below the kink point is studied.

This results of investigation of the influence of the characteristics of porous inclusions on the detonation parameters of emulsion explosives (EMX) are presented. Glass and polymer microballoons, perlite grains, hollow cenospheres, and a gas-generating additive are used as sensitizers. It is shown that polymer microballoons with an ultra-thin wall filled with isobutane are the most efficient sensitizer that almost fully unock the potential of EMX.

Ignition of RDX, HMX, and TATB by a nanosecond laser pulse is numerically simulated. The heat conduction equation in a cylindrical coordinate system is solved with allowance for multiple reflections of the light beam, zeroth-order exothermic reaction, and melting. Despite a small temperature gradient caused by a small coefficient of radiation absorption, violation of thermal equilibrium due to the Arrhenius nonlinearity leads to ignition of energetic materials from the surface. The critical energy density of PETN, RDX, HMX, and TATB ignition by a nanosecond laser pulse is determined. For identical absorption and reflection coefficients, the calculations show that the most sensitive explosive is PETN, whereas the most heat-resistance explosive is TATB.

This paper describes the micro-hotspot model of laser initiation of energy materials. The relationship of the critical energy density and the temperature of the reaction hotspot in PETN with the radii of nanoparticles of 12 metals at a pulse duration at half-height of 14 ns is determined. It is established that, as the nanoparticle radius is about 10 nm, the critical energy density tends to a certain value independent of heat capacity of metal. This is due to the reduction of the ratio of the nanoparticle volume to the volume of the heated PETN layer, which leads to the fact that most of the energy is spent on heating the matrix. It is shown that the critical hotspot temperature depends on both pulse duration and nanoparticle radius. The analytical expressions for the relationships of the critical parameters of reaction initiation with the radius and heat capacity of metal nanoparticles and for the relationship of the critical hotspot temperature with pulse duration are obtained. The invariant binding the critical energy density and the characteristic development time of the reaction is discovered. The results of this paper are necessary for the optimization of the composition of the optical detonator cell.

This paper presents data on laser initiation of low-density PETN mixtures with metal additives with varying dispersion of PETN and particle size of the additives. A laser with a wavelength of 1.06  m and a pulse length of 40 and 30 ns was used. Curves of the threshold initiation parameters on the additive content are shown to have minima. For coarse additives, no significant dependence of the initiation threshold of the mixtures on the nature of the metal at its optimum content (except for aluminum) was observed. For PETN mixtures with an optimum amount of fine aluminum, a significantly greater decrease in the threshold initiation parameters (a factor of 6.2) compared to direct initiation of PETN was found.àIt is shown that the initiation thresholds of the mixtures do not depend on the degree of dispersion of PETN with optimum content of additives. Increasing the degree of dispersion of PETN extends the dependences of the threshold parameters on the additive content while the optimum content is shifted to higher values. The initiation thresholds are found to strongly depend on the density of the mixture charge. The key points of the mechanism of laser initiation of PETN mixtures with additives are formulated.

This paper presents the results of experimental studies of the effect of damage and initial porosity of desensitized HMX samples on the limiting initiation conditions and explosion parameters under impact of steel spherical projectiles weighing 2-100 g. It is shown that preliminary mechanical damage to the explosive samples, as well as reduction in the initial density, leads to a qualitatively similar result - an increase in the limiting impactor velocity, causing initiation of the explosive transformation. The damage structure of the samples in the absence of initiation and the dependence of the physical and mechanical properties of samples on their density are studied.

Depending on the geometry and amplitude-time characteristics of external impact, there may be cumulation of shock-wave energy in the samples, which reduces the time durind which the structural materials retain their functional properties. The dispersion of the free metal surface of samples without and with pre-applied disturbances in the form of pyramids. Under certain amplitude-time characteristics of the external impact, dispersion from the tops of pyramids occurs. The quantitative characteristics of dynamic destructive processes at different amplitude-time characteristics of the external impact are determined for the purpose of introducing them into two- and three-dimensional codes to predict the behavior of metals under extreme conditions.

Education as a sophisticated open nonlinear subsystem of society seems to be in the state of constant conversion and reforming caused by both the internal and external factors. The process of reforming tends to have a permanent character; one novelty succeeds another exacerbating the conflict between subjective actions of reformers and ontologically given content of education. To resolve the conflict, the philosophical analysis of reflection on theory and practice of education is required. World-view and methodology functions of philosophy are able to reveal the essence of ideas about man, man’s spirituality and sociality. The paper gives the justification of a close connection between philosophy and pedagogical science, as well as of their distinctions. The paper specifies the functions of philosophy of education that provide versatile comprehension of education and its development. As one of the contemporary phenomena of the education, electronic learning is considered from the point of view of ontological approach.