1,004 research outputs found
PAN AIR: A computer program for predicting subsonic or supersonic linear potential flows about arbitrary configurations using a higher order panel method. Volume 4: Maintenance document (version 1.1)
The Maintenance Document is a guide to the PAN AIR software system, a system which computes the subsonic or supersonic linear potential flow about a body of nearly arbitrary shape, using a higher order panel method. The document describes the over-all system and each program module of the system. Sufficient detail is given for program maintenance, updating and modification. It is assumed that the reader is familiar with programming and CDC (Control Data Corporation) computer systems. The PAN AIR system was written in FORTRAN 4 language except for a few COMPASS language subroutines which exist in the PAN AIR library. Structured programming techniques were used to provide code documentation and maintainability. The operating systems accommodated are NOS 1.2, NOS/BE and SCOPE 2.1.3 on the CDC 6600, 7600 and Cyber 175 computing systems. The system is comprised of a data management system, a program library, an execution control module and nine separate FORTRAN technical modules. Each module calculates part of the posed PAN AIR problem. The data base manager is used to communicate between modules and within modules. The technical modules must be run in a prescribed fashion for each PAN AIR problem. In order to ease the problem of supplying the many JCL cards required to execute the modules, a separate module called MEC (Module Execution Control) was created to automatically supply most of the JCL cards. In addition to the MEC generated JCL, there is an additional set of user supplied JCL cards to initiate the JCL sequence stored on the system
PAN AIR: A computer program for predicting subsonic or supersonic linear potential flows about arbitrary configurations using a higher order panel method. Volume 4: Maintenance document (version 3.0)
The Maintenance Document Version 3.0 is a guide to the PAN AIR software system, a system which computes the subsonic or supersonic linear potential flow about a body of nearly arbitrary shape, using a higher order panel method. The document describes the overall system and each program module of the system. Sufficient detail is given for program maintenance, updating, and modification. It is assumed that the reader is familiar with programming and CRAY computer systems. The PAN AIR system was written in FORTRAN 4 language except for a few CAL language subroutines which exist in the PAN AIR library. Structured programming techniques were used to provide code documentation and maintainability. The operating systems accommodated are COS 1.11, COS 1.12, COS 1.13, and COS 1.14 on the CRAY 1S, 1M, and X-MP computing systems. The system is comprised of a data base management system, a program library, an execution control module, and nine separate FORTRAN technical modules. Each module calculates part of the posed PAN AIR problem. The data base manager is used to communicate between modules and within modules. The technical modules must be run in a prescribed fashion for each PAN AIR problem. In order to ease the problem of supplying the many JCL cards required to execute the modules, a set of CRAY procedures (PAPROCS) was created to automatically supply most of the JCL cards. Most of this document has not changed for Version 3.0. It now, however, strictly applies only to PAN AIR version 3.0. The major changes are: (1) additional sections covering the new FDP module (which calculates streamlines and offbody points); (2) a complete rewrite of the section on the MAG module; and (3) strict applicability to CRAY computing systems
Towards a more practical model for mixed criticality systems
Abstract-Mixed Criticality Systems (MCSs) have been the focus of considerable study over the last six years. This work has lead to the definition of a standard model that allows processors to be shared efficiently between tasks of different criticality levels. Key aspects of this model are that a system is deemed to execute in one of a small number of criticality modes; initially the system is in the lowest criticality mode, but if any task executes for more than its predefined budget for this criticality level then a mode change is made to a higher criticality mode and all tasks of the lowest criticality level are abandoned (aborted). The initial criticality level is never revisited. This model has been useful in defining key properties of MCSs, but it does not form a useful basis for an actual implementation of a MCS. In this paper we consider the tradeoffs stemming from a consideration of what systems engineers require at run-time and the actual properties of the model that scheduling analysis guarantees. Alternative models are defined that allow low criticality tasks to continue to execute after a criticality mode change. The paper also addresses robust priority assignment
Separated Oscillatory Fields for High-Precision Penning Trap Mass Spectrometry
Ramsey's method of separated oscillatory fields is applied to the excitation
of the cyclotron motion of short-lived ions in a Penning trap to improve the
precision of their measured mass. The theoretical description of the extracted
ion-cyclotron-resonance line shape is derived out and its correctness
demonstrated experimentally by measuring the mass of the short-lived Ca
nuclide with an uncertainty of using the ISOLTRAP Penning
trap mass spectrometer at CERN. The mass value of the superallowed beta-emitter
Ca is an important contribution for testing the conserved-vector-current
hypothesis of the electroweak interaction. It is shown that the Ramsey method
applied to mass measurements yields a statistical uncertainty similar to that
obtained by the conventional technique ten times faster.Comment: 5 pages, 4 figures, 0 table
Dynamics of light harvesting in ZnO nanoparticles
We have explored light harvesting of the complex of ZnO nanoparticles with the biological probe Oxazine 1 in the near-infrared region using picosecond-time-resolved fluorescence decay studies. We have used ZnO nanoparticles and Oxazine 1 as a model donor and acceptor, respectively, to explore the efficacy of the Förster resonance energy transfer (FRET) in the nanoparticle-dye system. It has been shown that FRET from the states localized near the surface and those in the bulk of the ZnO nanoparticles can be resolved by measuring the resonance efficiency for various wavelengths of the emission spectrum. It has been observed that the states located near the surface for the nanoparticles (contributing to visible emission at λ≈550 nm) can contribute to very high efficiency (>90%) FRET. The efficiency of light harvesting dynamics of the ZnO nanorods has also been explored in this study and they were found to have much less efficiency (∼40%) for energy transfer compared to the nanoparticles. The possibility of an electron transfer reaction has been ruled out from the picosecond-resolved fluorescence decay of the acceptor dye at the ZnO surface
Positron and positronium affinities in the work-formalism Hartree-Fock approximation
Positron binding to anions is investigated within the work formalism proposed
by Harbola and Sahni for the halide anions and the systems Li^- through O^-
excluding Be^- and N^-. The toal ground-state energies of the anion-positron
bound systems are empirically found to be an upper bound to the Hartree-Fock
energies. The computed expectation values as well as positron and positronium
affinities are in good agreement with their restricted Hartree-Fock
counterparts. Binding of a positron to neutral species is also investigated
using an iterative method.Comment: 12 pages, to appear in Physical Review
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