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.
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 ...
A simple method, requiring the work of a single SCF iteration, is presented for the construction of modified virtual orbitals (MVO's). Test calculations on H2O, Ar, and two states of CH2 show that for the truncati...
作者：
COLEMAN, EWHEFFNER, WHMr. Ernest W. Coleman is a Project Engineer in the Microwave Technology Branch
Radar Division Sensors & Avionics Technology Directorate. of the Naval Air Development Center (NADC). Warminster. Pa. He began his professional career at NADC in 1971 after receiving his B.S. degree in Electrical Engineering from the Tennessee Technological University. He has held several engineering positions in the areas of Design. Development. Simulation and Test & Evaluation of both antenna systems and avionics systems. He did his graduate study in Electromagnetics at Ohio State University and has authored several technical papers and numerous reports. Currently. he is Project Engineer for the development of an Adaptive Array Antenna to be used with future communication systems such as JTIDS. Mr. W. Herbert Heffner
Jr. is Head of the Microwave Technology Branch at NADC Wurminster. Pa. He received his B.S. degree in Electrical Engineering from Drexel University in 1962. and since then has held several design and development engineering positions at NADC and in the Naval Material Command. He attended Ohio State University during 1964 and 1965 receiving his M.S. degree in Electrical Engineering upon completion of his studies. For the past fourteen years he has been involved in the analysis. design development. and evaluation of aircraft antenna systems. radonies. and radar cross-section reduction techniques. In 1976. he was temporarily assigned as Program Element Administrator Surface and Aerospace Target Surveillance. under the Deputy Chief of Naval Material for Development. Naval Material Command. In his four years since returning to NADC. his responsibilities have included developing antennas for future Electronic Warfare and Communication Electronic Counter-Countermeasure applications as well as digital computer antenna analysis techniques and radar camouflage of tactical aircraft.
The Navy is developing an airborne adaptive array antenna for the Joint Tactical Information Distribution System (JTIDS). JTIDS is a Tri-Service multi-channel, multi-function system to provide an advanced communicatio...
The Navy is developing an airborne adaptive array antenna for the Joint Tactical Information Distribution System (JTIDS). JTIDS is a Tri-Service multi-channel, multi-function system to provide an advanced communication, navigation, and identification (CNI) capability for a wide variety of uses. JTIDS terminals perform multiple digital voice/data functions and relative navigation as well as the standard TACAN and IFF transponder functions. The system uses a low-duty cycle, spread-spectrum waveform and advanced coding techniques to provide secure, jam-resistant, and low probability of exploitation CNI functions. Among the important factors which determine the ultimate utility of a JTIDS terminal is the performance of the antenna system. Inadequate antenna performance could seriously degrade and possibly even negate the primary platform mission. Recent advances in antenna and data processing techndogiea promise to provide JTIDS with adequate gain and pattern coverage as well as substantial AJ (Anti-Jam) margin to complement JTIDS signal processing. The desired improvement in AJ protection can be achieved by capitalizing on the spatial filtering properties of adaptive array antennas. This paper presents the “trade-offs” which must be addressed in the design of an adaptive array antenna for airborne JTIDS terminals and the design philosophy currently in development by the Navy.
This paper presents an integrated approach to computer-Aided Ship Design for U.S. Navy preliminary and contract design. An integrated Hull Design System (HDS), currently under development by the Hull Group of the Nava...
This paper presents an integrated approach to computer-Aided Ship Design for U.S. Navy preliminary and contract design. An integrated Hull Design System (HDS), currently under development by the Hull Group of the Naval Sea Systems Command (NAVSEA 32). is the vehicle for the discussion. This paper is directed toward practicing ship design professionals and the managers of the ship design process. Primary emphasis of this paper, and of the development effort currently under way, is on aiding ship design professionals in their work. Focus is on integration and management control of the extremely complex set of processes which make up naval ship design. The terminology of the Ship Designer and Design Manager is used. The reader needs no familiarity with the technologies of computerscience.
The problem of finding an optimal dynamic assignment of a modular program for a two-processor system is analyzed. Stone's formulation of the static assignment problem is extended to include the cost of dynamically...
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The problem of finding an optimal dynamic assignment of a modular program for a two-processor system is analyzed. Stone's formulation of the static assignment problem is extended to include the cost of dynamically reassigning a module from one processor to the other and the cost of module residence without execution. By relocating modules during the course of program execution, changes in the locality of the program can be taken into account. It is shown that network flow algorithms may be used to find a dynamic assignment that minimizes the sum of module execution costs, module residence costs, intermodule communication costs, and module reassignment costs. Techniques for reducing the size of the problem are described for the case where the costs of residence are negligible.
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