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Critical Conditions of Self-Ignition at Bifurcation Points 分岔点自燃的临界条件
IF 0.6 4区 物理与天体物理
Doklady Physics Pub Date : 2024-01-29 DOI: 10.1134/S1028335823050063
A. A. Philippov,  A. A. Berlin
{"title":"Critical Conditions of Self-Ignition at Bifurcation Points","authors":"A. A. Philippov,&nbsp; A. A. Berlin","doi":"10.1134/S1028335823050063","DOIUrl":"10.1134/S1028335823050063","url":null,"abstract":"<p>The results of the main research in the field of self-ignition theory are summarized. For symmetrical vessels, the following are presented: critical conditions of spontaneous ignition in dimensional coordinates, temperature distribution in the vessel, pre-explosive heating of fuel, and the critical size of the vessel at the time of explosion. It is noted that the self-ignition conditions for various vessels differ only by a digital multiplier, which indicates that the shape of the vessel does not affect the physicochemical processes going on in the fuel at the time of the explosion. Each singular point, being a bifurcation point, determines a number that allows finding a single critical condition of self-ignition from the set of solutions to the heat equation. This condition, in the coordinates of its variables, represents a multidimensional surface separating the zone of stationary existence of a combustible system from the zone of “no return,” where a combustible system cannot exist.</p>","PeriodicalId":533,"journal":{"name":"Doklady Physics","volume":"68 6","pages":"186 - 189"},"PeriodicalIF":0.6,"publicationDate":"2024-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139648404","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Transition of a Supersonic Boundary Layer Over an Unswept Wing Due to Acoustic Noise 声学噪声导致未下垂机翼上超音速边界层的转变
IF 0.6 4区 物理与天体物理
Doklady Physics Pub Date : 2023-12-26 DOI: 10.1134/S1028335823040031
P. V. Chuvakhov,  I. V. Egorov
{"title":"Transition of a Supersonic Boundary Layer Over an Unswept Wing Due to Acoustic Noise","authors":"P. V. Chuvakhov,&nbsp; I. V. Egorov","doi":"10.1134/S1028335823040031","DOIUrl":"10.1134/S1028335823040031","url":null,"abstract":"<p>In this paper, we present the results of direct numerical modeling of the process of susceptibility of a supersonic boundary layer over an unswept wing with a thin parabolic profile to acoustic noise of various intensities. It was demonstrated that acoustic noise can cause a laminar–turbulent transition over the unswept wing of a supersonic passenger aircraft.</p>","PeriodicalId":533,"journal":{"name":"Doklady Physics","volume":"68 4","pages":"131 - 134"},"PeriodicalIF":0.6,"publicationDate":"2023-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139053201","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Features of Nitrogen Degassing of Dhajala Chondrite (3.8) 达贾拉软玉（3.8）的脱氮特征
IF 0.6 4区 物理与天体物理
Doklady Physics Pub Date : 2023-12-26 DOI: 10.1134/S1028335823040067
S. A. Voropaev, N. V. Dushenko, V. S. Fedulov, V. G. Senin
{"title":"Features of Nitrogen Degassing of Dhajala Chondrite (3.8)","authors":"S. A. Voropaev,&nbsp;N. V. Dushenko,&nbsp;V. S. Fedulov,&nbsp;V. G. Senin","doi":"10.1134/S1028335823040067","DOIUrl":"10.1134/S1028335823040067","url":null,"abstract":"<p>Samples of the Dhajala meteorite (ordinary chondrite, type H3.8) were kept isothermically in a specially designed device in the temperature range from 300 to 800°C for 90 minutes. The composition and content of the released gases were studied on a gas chromatograph. The following were detected: CO, CO<sub>2</sub>, and H<sub>2</sub>O in concentrations of 10–60 µg/g of the sample; in addition, H<sub>2</sub>, CH<sub>4</sub>, and H<sub>2</sub>S in concentrations of 0.3–2 µg/g. The total nitrogen content during degassing increased quasi-linearly over time from 1–2 to 10–12 µg/g at each fixed temperature. Based on experimental observations of the change in the rate of nitrogen release depending on temperature, it was concluded that the effect of phase transitions depends on the permeability of the mineral matrix.</p>","PeriodicalId":533,"journal":{"name":"Doklady Physics","volume":"68 4","pages":"135 - 139"},"PeriodicalIF":0.6,"publicationDate":"2023-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139053197","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Maintaining Microwave Discharge in Hollow Core Optical Fibers for Gas Fiber Lasers 维持气体光纤激光器空芯光纤中的微波放电
IF 0.6 4区 物理与天体物理
Doklady Physics Pub Date : 2023-12-26 DOI: 10.1134/S102833582304002X
I. A. Bufetov, A. V. Gladyshev, S. M. Nefedov, A. F. Kosolapov, V. V. Velmiskin, P. A. Goncharov, A. P. Mineev
{"title":"Maintaining Microwave Discharge in Hollow Core Optical Fibers for Gas Fiber Lasers","authors":"I. A. Bufetov,&nbsp;A. V. Gladyshev,&nbsp;S. M. Nefedov,&nbsp;A. F. Kosolapov,&nbsp;V. V. Velmiskin,&nbsp;P. A. Goncharov,&nbsp;A. P. Mineev","doi":"10.1134/S102833582304002X","DOIUrl":"10.1134/S102833582304002X","url":null,"abstract":"<p>The minimal values of the 2.45 GHz microwave electric field, which are necessary to maintain a discharge in a number of noble gases (argon, neon, and helium) in optical fibers with hollow cores of small diameter up to 100 μm, have been measured for the first time. The minimal electric field values for all three gases are (2.5–2.8) kV/cm at a pressure of argon ~50 Torr, neon ~300 Torr, and helium ~500 Torr.</p>","PeriodicalId":533,"journal":{"name":"Doklady Physics","volume":"68 4","pages":"107 - 112"},"PeriodicalIF":0.6,"publicationDate":"2023-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139053376","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Exact Solution of the Wiener–Hopf Equation on the Segment for Contact Problems of the Theory of Cracks in a Layered Medium 层状介质裂缝理论中接触问题分段上的维纳-霍普夫方程精确解法
IF 0.6 4区 物理与天体物理
Doklady Physics Pub Date : 2023-12-26 DOI: 10.1134/S1028335823040018
V. A. Babeshko, O. V. Evdokimova, O. M. Babeshko, M. V. Zaretskaya, V. S. Evdokimov
{"title":"Exact Solution of the Wiener–Hopf Equation on the Segment for Contact Problems of the Theory of Cracks in a Layered Medium","authors":"V. A. Babeshko,&nbsp;O. V. Evdokimova,&nbsp;O. M. Babeshko,&nbsp;M. V. Zaretskaya,&nbsp;V. S. Evdokimov","doi":"10.1134/S1028335823040018","DOIUrl":"10.1134/S1028335823040018","url":null,"abstract":"<p>This paper presents an approach that allows us for the first time to construct an exact solution of the Wiener–Hopf integral equations on a finite segment for the case of meromorphic functions in Fourier transforms of the kernel. The Wiener–Hopf integral equation is traditionally considered set on a semi-infinite segment. However, in applications, there are often cases of their application specified on a finite segment. For these purposes, approximate methods of applying these integral equations have been developed. However, when considering the Wiener–Hopf integral equations generated by mixed problems of continuum mechanics and mathematical physics in a multilayer medium of finite thickness, it turned out that these integral equations are solved exactly both on semi-infinite and finite segments. The approach is based on a new modeling method in differential equations and in some types of integral equations. It allows the reduction of Wiener–Hopf integral equations to infinite systems of linear algebraic equations that are solved exactly. The obtained result opens up the possibility of constructing exact solutions to boundary value problems for deformable stamps and cracks of a new type in bounded bodies.</p>","PeriodicalId":533,"journal":{"name":"Doklady Physics","volume":"68 4","pages":"120 - 124"},"PeriodicalIF":0.6,"publicationDate":"2023-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139053612","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Obtaining the Thermoelectric Material Cu2Se by the Self-Propagating High-Temperature Synthesis Method 利用自蔓延高温合成法获得热电材料 Cu2Se
IF 0.6 4区 物理与天体物理
Doklady Physics Pub Date : 2023-12-26 DOI: 10.1134/S1028335823040043
G. R. Nigmatullina, D. Yu. Kovalev,  M. I. Alymov
{"title":"Obtaining the Thermoelectric Material Cu2Se by the Self-Propagating High-Temperature Synthesis Method","authors":"G. R. Nigmatullina,&nbsp;D. Yu. Kovalev,&nbsp; M. I. Alymov","doi":"10.1134/S1028335823040043","DOIUrl":"10.1134/S1028335823040043","url":null,"abstract":"<p>Using the method of self-propagating high-temperature synthesis in the combustion mode, a product based on the α-Cu<sub>2</sub>Se phase was obtained from a 2Cu + Se powder mixture. The effect of synthesis conditions on the composition of the combustion product was studied, and the unit cell parameters of the synthesized phases were determined. It has been established that, as a result of combustion of pressed 2Cu+Se mixtures at an Ar pressure of 0.5–1.5 MPa, a product is formed containing two modifications of Cu<sub>2</sub>Se—the low-temperature monoclinic α-Cu<sub>2</sub>Se and high-temperature cubic β-Cu<sub>1.8</sub>Se phases. Combustion of a 2Cu+Se mixture of bulk density at an Ar pressure above 0.5 MPa yielded a single-phase product, the monoclinic α-Cu<sub>2</sub>Se phase.</p>","PeriodicalId":533,"journal":{"name":"Doklady Physics","volume":"68 4","pages":"113 - 119"},"PeriodicalIF":0.6,"publicationDate":"2023-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139053332","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
The Moment-Membrane Theory of Elastic Flexible Plates as a Continual Geometrically Nonlinear Theory of a Graphene Sheet 弹性柔性板的动量-膜理论作为石墨烯薄片的连续几何非线性理论
IF 0.6 4区 物理与天体物理
Doklady Physics Pub Date : 2023-12-26 DOI: 10.1134/S1028335823040055
S. H. Sargsyan
{"title":"The Moment-Membrane Theory of Elastic Flexible Plates as a Continual Geometrically Nonlinear Theory of a Graphene Sheet","authors":"S. H. Sargsyan","doi":"10.1134/S1028335823040055","DOIUrl":"10.1134/S1028335823040055","url":null,"abstract":"<p>A geometrically nonlinear moment-membrane theory of elastic plates has been built as a continual theory of deformations of flexible graphene under the assumption of smallness of deformations, bending-torsional characteristics, and angles of rotation (including a free one) of plate elements on the basis of the 3D geometrically nonlinear moment theory of elasticity with preservation of only the nonlinear terms that come from normal displacement (deflection) and its derivatives. For this nonlinear theory of elastic plates, the resolving equations are presented also in mixed form by introducing stress functions: this is a system of equilibrium equations for the transverse bending deformation compiled in the deformed state of the plate and the deformation continuity equations expressed by the stress and deflection functions. The Lagrangian-type variational principle for the geometrically nonlinear moment-membrane theory of elastic plates has been established.</p>","PeriodicalId":533,"journal":{"name":"Doklady Physics","volume":"68 4","pages":"125 - 130"},"PeriodicalIF":0.6,"publicationDate":"2023-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139053198","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Elastic-Wave Scattering by a Plane Crack: Application of Flaw Detection 平面裂缝的弹性波散射：缺陷检测的应用
IF 0.6 4区 物理与天体物理
Doklady Physics Pub Date : 2023-12-25 DOI: 10.1134/S1028335823030011
N. P. Aleshin, L. Yu. Mogilner
{"title":"Elastic-Wave Scattering by a Plane Crack: Application of Flaw Detection","authors":"N. P. Aleshin,&nbsp;L. Yu. Mogilner","doi":"10.1134/S1028335823030011","DOIUrl":"10.1134/S1028335823030011","url":null,"abstract":"<p>The 3D problem of elastic wave scattering by a crack in the form of a half-plane in an elastic medium is considered. It is noted that the previously published solutions do not fully cover the issues relevant to ultrasonic flaw detection, for example, detecting transverse cracks in welds. The proposed solution is made by the Wiener–Hopf technique. It is shown that scattered longitudinal and transverse waves can be generally written in closed form. Some features of the identification of the tip of transverse cracks are noted, including scattering features during sonication of cracks along their surface and the influence of critical angles.</p>","PeriodicalId":533,"journal":{"name":"Doklady Physics","volume":"68 3","pages":"97 - 105"},"PeriodicalIF":0.6,"publicationDate":"2023-12-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139053597","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Symmetry of the Lundgren–Monin–Novikov Equation for the Probability Distribution of the Vortex Field 涡流场概率分布的伦德格伦-莫宁-诺维科夫方程的对称性
IF 0.6 4区 物理与天体物理
Doklady Physics Pub Date : 2023-12-25 DOI: 10.1134/S1028335823010044
V. N. Grebenev, A. N. Grishkov, M. Oberlack
{"title":"Symmetry of the Lundgren–Monin–Novikov Equation for the Probability Distribution of the Vortex Field","authors":"V. N. Grebenev,&nbsp;A. N. Grishkov,&nbsp;M. Oberlack","doi":"10.1134/S1028335823010044","DOIUrl":"10.1134/S1028335823010044","url":null,"abstract":"<p>Polyakov [Nuclear Phys. B, 396, 1993] proposed a program for expanding the group of symmetries of hydrodynamic models to the conformal invariance of statistics in inverse cascades, where the conformal group is infinite-dimensional. This study presents group <i>G</i> of transformations of the equation for an <span>(n)</span>-point probability density function <i>f</i><sub><i>n</i></sub> (PDF) from an infinite chain of the Lundgren–Monin–Novikov equations (the statistical form of the Euler equations) for the field of a vortex of two-dimensional flow. The main result obtained is that the group <i>G</i> transforms conformally the characteristics of the zero-vorticity equation and, invariantly, the family of the <i>f</i><sub><i>n</i></sub> equations for the PDF along these lines. Along with other characteristics, the equation is not invariant. The action of <i>G</i> retains the PDF class. The results obtained can be used to study the invariance of the statistical properties in optical turbulence.</p>","PeriodicalId":533,"journal":{"name":"Doklady Physics","volume":"68 3","pages":"92 - 96"},"PeriodicalIF":0.6,"publicationDate":"2023-12-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139053635","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Experimental Study of the Nonmodal Perturbation Growth Mechanism in a Laminar Submerged Jet 层流浸没式喷流中的非模态扰动增长机制实验研究
IF 0.6 4区 物理与天体物理
Doklady Physics Pub Date : 2023-12-25 DOI: 10.1134/S1028335823020015
D. A. Ashurov, V. V. Vedeneev, L. R. Gareev, O. O. Ivanov
{"title":"Experimental Study of the Nonmodal Perturbation Growth Mechanism in a Laminar Submerged Jet","authors":"D. A. Ashurov,&nbsp;V. V. Vedeneev,&nbsp;L. R. Gareev,&nbsp;O. O. Ivanov","doi":"10.1134/S1028335823020015","DOIUrl":"10.1134/S1028335823020015","url":null,"abstract":"<p>It is known that, in wall-bounded flows, along with the growth of instability modes, an important role is played by the nonmodal (algebraic) mechanism of linear growth. In unbounded flows, including submerged jets, the nonmodal growth mechanism has been theoretically studied only in the last decade; this mechanism has not yet been identified in experiments. This paper describes experiments on excitation of the nonmodal “lift-up” growth mechanism. Special wavy structures (deflectors) are introduced into a laminar submerged jet of circular cross section, which excites a roller-like transverse motion. The data obtained make it possible to identify unambiguously the nonmodal lift-up growth of the introduced perturbations. The development of perturbations in the experiment qualitatively agrees with the theoretically calculated optimal perturbations. The specificities of the transition to turbulence caused by nonmodal growth are considered.</p>","PeriodicalId":533,"journal":{"name":"Doklady Physics","volume":"68 3","pages":"77 - 86"},"PeriodicalIF":0.6,"publicationDate":"2023-12-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139053087","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
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