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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 1,693 records · Page 94
All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

Generalized Continuum Phenomenological Model of Viscous Fluid: Analysis of Local Mass Displacements

The concept of local mass displacements (as a measure of nonlocality of the state of a physically small element of a body) is used to formulate a complete system of relations of the gradient-type mathematical model of viscous compressible fluid. In this model, the relationship between the thermomechanical processes and the process of local mass displacements, its irreversibility, and the inertia properties are taken into account. It is shown that, in the stationary approximation, the obtained system of relations enables us to justify the appearance of wedging pressure in thin interlayers of fluid.

42 ENGINEERING↗
DOE OSTI2018

Differential-Invariant Solutions

We construct differential-invariant solutions to automorphic systems and propose a method for classifying differential-invariant submodels.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2018

On the Problem on Slow Entrance of a Flat Piston in Compressed Liquid

In this paper, slow movement of a flat piston in compressed liquid is considered. The solution of the problem is constructed with two different methods: the first is based on the theory of Riemann’s simple waves, and the second on the small parameter method. Then we compare the results obtained by the two methods.

42 ENGINEERING↗
DOE OSTI2018

The Bohl–Perron Theorem for Hybrid Linear Systems with Aftereffect

We consider an abstract hybrid system of functional-differential equations. Both equations are functional-differential with respect to one part of variables and difference with respect to to the other part of variables. To the system of two equations with two unknowns appeared, we apply the W-method of N. V. Azbelev. We examine two models: a system of functional-differential equations and a system of difference equations. We study the spaces of their solutions and obtain the Bohl–Perron-type theorems on the exponential stability.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2018

On the global behavior of homeomorphisms of metric spaces

For the metric spaces, the homeomorphisms more general than conformal mappings are studied. It is proved that the families of ine indicated mappings are equicontinuous in their closure under definite conditions imposed on the boundaries of the corresponding domains.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2018

Initial-Boundary Value Problem for the Non-Stationary Radiative Transfer Equation with Fresnel Reflection and Refraction Conditions

We consider the initial-boundary value problems for the nonstationary radiative transfer equation in a system of semitransparent bodies with boundary and initial data in the complete scale of Lebesgue spaces. We establish the unique solvability of the first initial-boundary value problem, the problem with “shooting conditions,” and the problem with Fresnel reflection and refraction conditions on the body boundaries.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2018

Abstract Interpolating Fraction of the Thiele Type

We construct an abstract continued fraction of the Thiele type as an interpolating fraction for a nonlinear operator acting from a linear topological space X to an algebra Y with identity. In some special cases, this fraction transforms either into a classical Thiele fraction or into a matrix-valued fraction of the Thiele type depending on many variables.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2018

Generalized Bessel–Struve Operator and Its Properties

We define the generalized Bessel–Struve operator in the space of functions analytic in an arbitrary domain. The conditions of equivalence of the generalized Bessel–Struve operator to the operator of second derivative are investigated. We also describe the commutant of the generalized Bessel–Struve operator and establish its hypercyclicity and chaotic nature.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2018

Singular Ibragimov–Mamontov Type Equations

We study an Ibragimov–Mamontov type equation with singular Bessel operators playing the role of second order derivatives. We obtain a representation of the solution by using a special Bessel transform.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2018

Local-Global Principle for the General Quadratic and General Hermitian Groups and the Nilpotency of KH{sub 1}

In this article, an analog of the Quillen–Suslin’s local-global principle was established for the elementary subgroup of the general quadratic group and the general Hermitian group. It is shown that unstable K{sub 1}-groups of the general Hermitian groups over module finite rings are nilpotent-by-Abelian. This generalizes earlier results by A. Bak, R. Hazrat, and N. Vavilov.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2018

Nonstationary Problem of Complex Heat Transfer in a System of Semitransparent Bodies with Boundary-Value Conditions of Diffuse Reflection and Refraction of Radiation

We consider a nonstationary initial boundary-value problem describing complex (radiative-conductive) heat transfer in a system of semitransparent bodies. To describe radiation propagation, we use the radiation transfer equation with boundary-value conditions of diffuse reflection and refraction of radiation. We take into account that the radiation intensity and optical properties of bodies depend on the radiation frequency. The unique solvability of a weak solution is established. The comparison theorem is proved. A priori estimates of a weak solution as well as its regularity are obtained.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2018

On Construction of Anticliques for Noncommutative Operator Graphs

In this paper, we construct anticliques for noncommutative operator graphs generated by generalized Pauli matrices. It is shown that application of entangled states for the construction of the code space K allows one to substantially increase the dimension of a noncommutative operator graph for which the projection on K is an anticlique.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗