Coherence of coupling Riemann solvers for gas flows through flux-maximizing valves

In this paper we propose a model, based on the strictly hyperbolic system of isothermal Euler equations , for the gas flow in a straight pipe with a valve. We are then faced with an initial value problem with coupling conditions at the valve position. The valves under consideration are requested to maximize the flux; moreover, the flow is imposed to occur within prescribed bounds of pressure and flow. The issue is the mathematical characterization of the coherence of the corresponding coupling Riemann solvers; this property is related to the phenomenon of chattering, the rapid switch on and off of the valve. Within this framework we describe three kinds of valves, which differ for their action; two of them lead to a coherent solver, the third one does not. Proofs involve geometric and analytic properties of the Lax curves

Aeronautical engineering: A continuing bibliography with indexes (supplement 271)

This bibliography lists 666 reports, articles, and other documents introduced into the NASA scientific and technical information system in October, 1991. Subject coverage includes design, construction and testing of aircraft and aircraft engines; aircraft components, equipment and systems; ground support systems; and theoretical and applied aspects of aerodynamics and general fluid dynamics

Generalized averaged Gaussian quadrature and applications

A simple numerical method for constructing the optimal generalized averaged Gaussian quadrature formulas will be presented. These formulas exist in many cases in which real positive GaussKronrod formulas do not exist, and can be used as an adequate alternative in order to estimate the error of a Gaussian rule. We also investigate the conditions under which the optimal averaged Gaussian quadrature formulas and their truncated variants are internal

MS FT-2-2 7 Orthogonal polynomials and quadrature: Theory, computation, and applications

Quadrature rules find many applications in science and engineering. Their analysis is a classical area of applied mathematics and continues to attract considerable attention. This seminar brings together speakers with expertise in a large variety of quadrature rules. It is the aim of the seminar to provide an overview of recent developments in the analysis of quadrature rules. The computation of error estimates and novel applications also are described

Aeronautical engineering: A cumulative index to a continuing bibliography (supplement 274)

This publication is a cumulative index to the abstracts contained in supplements 262 through 273 of Aeronautical Engineering: A Continuing Bibliography. The bibliographic series is compiled through the cooperative efforts of the American Institute of Aeronautics and Astronautics (AIAA) and the National Aeronautics and Space Administration (NASA). Seven indexes are included: subject, personal author, corporate source, foreign technology, contract number, report number, and accession number