Beam-foil spectroscopy of oxygen in the wavelength region from 270 to 490 Å

1978 ◽  
Vol 56 (5) ◽  
pp. 508-516 ◽  
Author(s):  
Eric H. Pinnington ◽  
Keith E. Donnelly ◽  
J. Anthony Kernahan ◽  
David J. G. Irwin
Keyword(s):  
Satisfactory Agreement ◽  
Wavelength Region ◽  
Theoretical Predictions ◽  
The Mean ◽  
Theoretical Results ◽  
Beam Foil ◽  
Foil Technique ◽  
Good Agreement

We have used the beam-foil technique to study the spectrum of oxygen between 270 and 490 Å. We have measured the mean lives of the 3d2F, 3d4P, 3d4D, 3d′ 2D, 3d′ 2F, 4d4P, and 4d4D terms of O II, the 3s1P0, 3s3P0, 3S5P, 3s′ 3D, 3d3P, 3d3D, 3d3F, and 3d5P terms of O III, and the 3S2S, 3P2P0, and 3s4P0 terms of O IV. All cascade components are adequately explained. Good agreement is found with previous measurements in most cases, but significant discrepancies are found with some earlier results obtained using branches above 2000 Å. Generally satisfactory agreement is also found with theoretical predictions, although disagreement is found for several members of the 2p3–2p23d array in O II f-Values are computed for 18 individual lines, and compared with other experimental and theoretical results. Finally, we discuss briefly the f-value trends along the 2p23P–2p3s3P0 (O III), 2p21D–2p3s1P0 (O III), 2s2p24P–2s2p(3P0)3s4P0 (O IV), and 2p2P0–3s2S (O IV) isoelectronic sequences.

Fluorine mean-life measurements below 1000 Å using the beam–foil technique

1976 ◽  
Vol 54 (10) ◽  
pp. 1014-1021 ◽  
Author(s):  
E. H. Pinnington ◽  
D. J. G. Irwin ◽  
A. E. Livingston ◽  
J. A. Kernahan
Keyword(s):  
Satellite Data ◽  
Wavelength Region ◽  
Wave Functions ◽  
Interstellar Clouds ◽  
Beam Foil ◽  
Foil Technique ◽  
Good Agreement

We have used the beam–foil technique to measure mean lives for 16 transitions in F I–F IV in the wavelength region 400 Å–1000 Å. Good agreement is found with the results of recent calculations, particularly those employing correlated wave functions. The f-value trends for 5 isoelectronic sequences are presented in detail (2p5 2P0–2p43s2 D and 2p5 2P0–2p43s 2P in F I; 2p4 3P–2p33s 3D0 in F II; 2p3 2D0–2s2p4 2D and 2p3 4S0–2s2p4 4P in F III). Our f value for the 955 Å multiplet in F I is also used in conjunction with some new satellite data to show that the fluorine abundance is apparently depleted in interstellar clouds by a factor of at least 3 below its solar value.

Beam-foil lifetime measurements for some 2p3nl terms of singly-ionized fluorine

1979 ◽  
Vol 57 (7) ◽  
pp. 1046-1050 ◽  
Author(s):  
Eric H. Pinnington ◽  
Robert N. Gosselin ◽  
David J. G. Irwin ◽  
James A. O'Neill
Keyword(s):  
Wavelength Region ◽  
Lifetime Measurements ◽  
Experimental Values ◽  
Beam Foil ◽  
Foil Technique ◽  
Good Agreement

We have used the beam-foil technique in the wavelength region between 3500 and 4500 Å to measure the lifetimes of 10 terms in F II having the configuration 2p3nl, and also to demonstrate the usefulness of the ANDC method for overcoming the effects of cascade repopulation in these measurements. Our results are in good agreement with theory and with other experimental values.

scholarly journals Elasto-capillary coalescence of multiple parallel sheets

2013 ◽  
Vol 723 ◽  
pp. 692-705 ◽  
Author(s):  
A. D. Gat ◽  
M. Gharib
Keyword(s):  
Energy Analysis ◽  
Minimal Energy ◽  
Common Assumption ◽  
Viscous Forces ◽  
Theoretical Predictions ◽  
The Mean ◽  
The Stability ◽  
Elastic Sheets ◽  
Theoretical Results ◽  
Good Agreement

AbstractWe analyse two-dimensional clamped parallel elastic sheets which are partially immersed in liquid as a model for elasto-capillary coalescence. In the existing literature this problem is studied via minimal energy analysis of capillary and elastic energies of the post-coalescence state, yielding the maximal stable post-coalescence bundle size. Utilizing modal stability analysis and asymptotic analysis, we studied the stability of the configuration before the coalescence occurred. Our analysis revealed previously unreported relations between viscous forces, body forces, and the instability yielding the coalescence, thus undermining a common assumption that coalescence will occur as long as it will not create a bundle larger than the maximal stable post-coalesced size. A mathematical description of the process creating the hierarchical coalescence structure was obtained and yielded that the mean number of sheets per coalesced region is limited to the subset ${2}^{N} $ where $N$ is the set of natural numbers. Our theoretical results were illustrated by experiments and good agreement with the theoretical predictions was observed.

Line identifications and lifetime measurements in singly and doubly excited C IV and in C V

1980 ◽  
Vol 58 (8) ◽  
pp. 1093-1098 ◽  
Author(s):  
C. Jacques ◽  
E. J. Knystautas ◽  
R. Drouin ◽  
H. G. Berry
Keyword(s):  
Lifetime Measurements ◽  
Radiative Lifetimes ◽  
Doubly Excited ◽  
Theoretical Predictions ◽  
Beam Foil ◽  
Foil Technique ◽  
Good Agreement

Forty-eight new uv lines have been observed and identified in the singly and doubly excited systems of C IV, and in C V. The beam-foil technique was used to excite the spectra and to measure radiative lifetimes for 16 levels. Good agreement is found with available theoretical predictions.

Analysis of Dispersion of Small Spherical Particles in a Random Velocity Field

1990 ◽  
Vol 112 (1) ◽  
pp. 114-120 ◽  
Author(s):  
H. Ounis ◽  
G. Ahmadi
Keyword(s):  
Particle Velocity ◽  
Digital Simulation ◽  
Density Ratio ◽  
Spherical Particles ◽  
Theoretical Predictions ◽  
The Mean ◽  
Analysis Of Dispersion ◽  
Gradient Effects ◽  
Analytical Expressions ◽  
Good Agreement

The equation of motion of a small spherical rigid particle in a turbulent flow field, including the Stokes drag, the Basset force, and the virtual mass effects, is considered. For an isotropic field, the lift force and the velocity gradient effects are neglected. Using the spectral method, responses of the resulting constant coefficient stochastic integrao-differential equation are studied. Analytical expressions relating the Lagrangian energy spectra of particle velocity to that of the fluid are developed and the results are used to evaluate various response statistics. Variations of the mean-square particle velocity and particle diffusivity with size, density ratio and response time are studied. The theoretical predictions are compared with the digital simulation results and the available data and good agreement is observed.

Vibration of a Rotating Asymmetric Shaft Supported in Asymmetric Bearings

1968 ◽  
Vol 10 (3) ◽  
pp. 252-261 ◽  
Author(s):  
H. F. Black ◽  
A. J. McTernan
Keyword(s):  
Natural Frequencies ◽  
Equations Of Motion ◽  
Forced Vibrations ◽  
Variation Method ◽  
Approximate Theory ◽  
Cross Sectional ◽  
Mass Unbalance ◽  
The Mean ◽  
Theoretical Results ◽  
Good Agreement

The parametrically excited vibrations of this system with assumed small asymmetry of the shaft cross-section are discussed in terms of the motion of a symmetric shaft having the mean cross-sectional flexibility, and the equations of motion are solved by the approximate perturbation-variation method of Hsu. Both features yield a more lucid appreciation of the motions expected than previous treatments: in particular, simpler explicit expressions for unstable bounds are given and forced vibrations due to mass unbalance are discussed with greater facility. The practically important case of nearly coincident natural frequencies is examined. The theoretical results are compared with analogue computation: good agreement with the approximate theory is found even for quite large shaft asymmetry.

Thermal Behavior and Friction in Journal Bearings

1970 ◽  
Vol 92 (3) ◽  
pp. 373-380 ◽  
Author(s):  
Al. Nica
Keyword(s):  
Experimental Data ◽  
Thermal Behavior ◽  
Heat Dissipation ◽  
Journal Bearings ◽  
Friction Torque ◽  
Operating Characteristics ◽  
Lubricant Flow ◽  
Theoretical Predictions ◽  
Theoretical Results ◽  
Good Agreement

This paper deals with friction and the field of temperature in the lubricant film of journal bearings. Theoretical results regarding the thermal behavior are checked with experimental data and good agreement is found. Emphasis is put on the variation of temperature and lubricant flow with the operating characteristics of the bearing and it is seen that theoretical predictions for minima of friction torque are backed by temperature measurements. Further on, the friction torque and the mechanism of heat dissipation in bearings are dealt with, in order to verify the assumptions used in the calculation schemes. The means of efficiently cooling the bearing are also discussed, as well as the part played by the divergent zone in this process.

scholarly journals The Dynamics of the S(1D)+H2/D2 Reactions at Low Temperature via Statistical Simulations

2020 ◽  
Vol 3 (1) ◽  
pp. 9-16
Author(s):  
Tomas Gonzalez-Lezana ◽  
Pascal Larrégaray ◽  
Laurent Bonnet
Keyword(s):  
Cross Sections ◽  
Quantum Model ◽  
Space Theory ◽  
Collisional Energy ◽  
Energy Regime ◽  
Phase Space Theory ◽  
The Mean ◽  
Statistical Approaches ◽  
Theoretical Results ◽  
Good Agreement

Two different statistical approaches, the statistical quantum model (SQM) and the mean potential phase space theory (MPPST), have been employed to calculate the integral cross sections for the reactive collisions between S(1D) and H2/ D2  in the low energy regime (below 0.3 eV collisional energy). The rate constant for the S(1D) + H2 → SH + H reaction has been also obtained and compared with previously reported experimental and theoretical results. The good agreement shows the capability of these two methods to study the dynamics of these complex-forming atom-diatom processes in the present energy regime.

scholarly journals Generalized Softened Variable Angle Truss Model for RC Hollow Beams under Torsion

Materials ◽  
2019 ◽  
Vol 12 (13) ◽  
pp. 2209
Author(s):  
Luís Bernardo
Keyword(s):  
Solution Procedure ◽  
Pure Torsion ◽  
Specific Behavior ◽  
Torsional Response ◽  
Truss Model ◽  
Variable Angle ◽  
Theoretical Predictions ◽  
Hollow Beams ◽  
Theoretical Results ◽  
Good Agreement

In recent studies, a new softened truss model called Generalized Softened Variable Angle Truss Model (GSVATM) has been proposed to compute the full torsional response of reinforced concrete (RC) rectangular solid beams under pure torsion. In this article, the GSVATM is extended to cover RC hollow beams under torsion. The modification of the calculation procedure, in order to account for the specific behavior of RC hollow beams for low loading levels, as well as the final solution procedure, is presented. The theoretical predictions from the extended GSVATM are compared with experimental results of RC hollow beams under torsion found in the literature. Good agreement is observed between the experimental and theoretical results, for both high and low loading levels.

On the computation of dipole transitions in the HD molecule. Part II

1976 ◽  
Vol 54 (6) ◽  
pp. 672-679 ◽  
Author(s):  
L. Wolniewicz
Keyword(s):  
Ground State ◽  
Wave Functions ◽  
Nonadiabatic Coupling ◽  
Transition Moments ◽  
The Mean ◽  
Variational Wave Functions ◽  
Theoretical Results ◽  
Variational Wave ◽  
Electronic Ground ◽  
Good Agreement

The nonadiabatic coupling with Πu states in the electronic ground state of the HD molecule is discussed. Formulas are given that facilitate the evaluation of Πu contributions to the energies and transition moments. Numerical computations are performed for all ν ≤ 4 vibrational and J ≤ 4 rotational levels yielding the Πu and Σu nonadiabatic corrections. The variational wave functions are employed to compute the transition moments for the 0–ν bands with ν ≤ 4. The results are in good agreement with experimental data except in the case of the 0–ν band where the theoretical results are larger than the mean experimental moment by a factor of about 1.4.

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