Approximation schemes based on Legendretau approximation are developed for the estimation problems of delay and partial differential equations. A number of numerical examples are given to demonstrate the feasibility o...
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Approximation schemes based on Legendretau approximation are developed for the estimation problems of delay and partial differential equations. A number of numerical examples are given to demonstrate the feasibility of our numerical schemes.
One of the most serious problems encountered in Naval steam plants following World War II was the unreliable performance of boiler and main feedpump pneumatic control systems. In addition to control component and syst...
One of the most serious problems encountered in Naval steam plants following World War II was the unreliable performance of boiler and main feedpump pneumatic control systems. In addition to control component and system design deficiencies, these control systems suffered from inadequate methods to measure and adjust system alignment. This paper describes the development of a set of procedures for on-line alignment verification (OLV) of pneumatic main boiler and feedpump control systems. The procedures are designed for use by N avy control system technicians and, in addition to on-line alignment verification, provide guidance for troubleshooting and for performing system alignment. Procedure static checks measure steady state steaming performance and OLV procedure dynamic checks measure the ability of the boiler and control systems to respond to load changes. The paper describes typical control system characteristics that influence OLV procedure content and the supporting analysis that was used to establish alignment criteria ranges that satisfy both steady state and transient performance requirements. Also described is the alignment criteria tolerance analysis along with the steps involved in a typical OLV check procedure development. Descriptions of the various OLV checks, troubleshooting procedures and alignment procedures are provided. Typical shipboard implementation requirements are described and experience to date with the procedures is provided along with a status report on OLV procedure implementations.
There are various viscometric flow models available at present to determine the mechanical properties of incompressible non-Newtonian fluids. In most of these, measurement of the normal stresses is quite a challenge. ...
There are various viscometric flow models available at present to determine the mechanical properties of incompressible non-Newtonian fluids. In most of these, measurement of the normal stresses is quite a challenge. We introduce a new viscometric flow model and derive a theory for the measurement of the “second normal stress”. We also indicate how such a measurement can be performed in practice.
A systematic study of inflow and outflow boundary conditions for the numerical solution of the compressible Navier-Stokes equations is presented. Combinations of several representative inflow and outflow boundary cond...
A systematic study of inflow and outflow boundary conditions for the numerical solution of the compressible Navier-Stokes equations is presented. Combinations of several representative inflow and outflow boundary conditions are applied in the solution of subsonic flow over a flat plate in a finite computational domain. These boundary conditions are evaluated in terms of their effect on the accuracy of the solution and the rate of convergence to a steady state. It is shown that errors in the data specified at the inflow boundary can produce significant errors in the computed flow field. It is also shown that a non-reflecting outflow boundary condition can significantly reduce the total computational time required.
The shape of a vertical slender jet of fluid falling steadily under the force of gravity is studied. The problem is formulated as a nonlinear free boundary-value problem for the potential. Surface tension effects are ...
The shape of a vertical slender jet of fluid falling steadily under the force of gravity is studied. The problem is formulated as a nonlinear free boundary-value problem for the potential. Surface tension effects are neglected. The use of perturbation expansions results in a system of equations that can be solved by an efficient numerical procedure. Computations were made for jets issuing from orifices in various shapes including an ellipse, a rectangle, and an equilateral triangle. Computational results are presented illustrating the propagation of discontinuities and the formation of thin sheets of fluid.
This paper treats the stability of the initial boundary value problem for the method of lines applied to hyperbolic and parabolic partial differential equations in one space dimension. The theory treats the case of va...
This paper treats the stability of the initial boundary value problem for the method of lines applied to hyperbolic and parabolic partial differential equations in one space dimension. The theory treats the case of variable coefficients and allows for very general boundary conditions. Several examples are given which illustrate the theory. The theory is analogous to that developed by Gustafsson, Kreiss, and Sundström for finite-difference methods.
Accurate ab initio calculations have been performed on the 1 B 1 state of methylene. The basis set was of better than triple-zeta quality and included two sets of polarization functions. This work combined with previo...
Accurate ab initio calculations have been performed on the 1 B 1 state of methylene. The basis set was of better than triple-zeta quality and included two sets of polarization functions. This work combined with previous work yields a 1 A 1 - 1 B 1 separation of 1.07 eV. This determination is compared to those using Franck-Condon factors.
The dissociation energy and the equilibrium bond length are calculated for CIO at the first order CI level for a variety of basis sets, consisting of both standard atomic centered basis sets and those including bond f...
The dissociation energy and the equilibrium bond length are calculated for CIO at the first order CI level for a variety of basis sets, consisting of both standard atomic centered basis sets and those including bond functions. The basis sets with bond function are found to have a CI superposition error many times that of the standard atomic centered basis sets.
Using ab initio (with effective core potentials) electronic structure theory, the equilibrium geometry and singlet-triplet separation were determined for CBr2. The triplet was computed by using a single-configuration ...
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