Observation of new lines in the microwave spectrum of ortho-H2 pairs in solid hydrogen

1980 ◽  
Vol 58 (9) ◽  
pp. 1326-1340 ◽  
Author(s):  
B. W. Statt ◽  
W. N. Hardy ◽  
R. Jochemsen
Keyword(s):  
Solid Hydrogen ◽  
Microwave Spectrum ◽  
State Transitions ◽  
Nearest Neighbour ◽  
Microwave Spectrometer ◽  
Nearest Neighbours ◽  
Out Of Plane ◽  
Theoretical Predictions ◽  
Experimental Values ◽  
Potential Parameters

New microwave absorption spectra of ortho pairs in low ortho concentration samples of solid hydrogen are reported. Three excited state transitions which fix the position of the 10 Γ level for both types of nearest neighbour pairs are reported, and compared with the theoretical predictions of Harris, Berlinsky, and Hardy and Luryi and Van Kranendonk. Several new lines from the out-of-plane configuration are reported which confirm previous assignments. In contrast, two new lines from the next nearest neighbour spectrum support a reassignment of transitions for this configuration. A fit to this data determines several of the anisotropic potential parameters for next nearest neighbours. The improvements in the microwave spectrometer essential to obtaining the new results are also described. Finally, we compare our results to the most recent theoretical potential parameters of Schaefer and Meyer. A long standing discrepancy between theoretical and experimental values for the phonon renormalizationof Γ appears to be resolved by use of the new potential which has a substantial (~10%) non-quadrupolar contribution to ε4(R).

scholarly journals An Additive Model to Predict the Rheological and Mechanical Properties of Polypropylene Blends Made by Virgin and Reprocessed Components

Recycling ◽  
2021 ◽  
Vol 6 (1) ◽  
pp. 2
Author(s):  
Francesco Paolo La Mantia ◽  
Maria Chiara Mistretta ◽  
Vincenzo Titone
Keyword(s):  
Experimental Data ◽  
Mechanical Properties ◽  
Additive Model ◽  
Industrial Process ◽  
Theoretical Predictions ◽  
Experimental Values ◽  
Polypropylene Blends ◽  
Polypropylene Sample

In this work, an additive model for the prediction of the rheological and mechanical properties of monopolymer blends made by virgin and reprocessed components is proposed. A polypropylene sample has been reprocessed more times in an extruder and monopolymer blends have been prepared by simulating an industrial process. The scraps are exposed to regrinding and are melt reprocessed before mixing with the virgin polymer. The reprocessed polymer is, then, subjected to some thermomechanical degradation. Rheological and mechanical experimental data have been compared with the theoretical predictions. The results obtained showed that the values of this simple additive model are a very good fit for the experimental values of both rheological and mechanical properties.

scholarly journals Ro-vibrational energies of cesium dimer and lithium dimer with molecular attractive potential

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
C. A. Onate ◽  
T. A. Akanbi ◽  
I. B. Okon
Keyword(s):  
Thermal Properties ◽  
Attractive Potential ◽  
Average Deviation ◽  
Radial Wave ◽  
Lithium Dimer ◽  
Temperature Parameter ◽  
Vibrational Energies ◽  
Experimental Values ◽  
Uvarov Method ◽  
Potential Parameters

AbstractAn approximate solution of the Schrӧdinger equation for a molecular attractive potential was obtained using the parametric Nikiforov–Uvarov method. The energy equation and the corresponding radial wave functions were calculated. The effects of the potential parameters on the energy eigenvalues were examined. The thermal properties under the molecular attractive potential were calculated and the behaviour of the thermal properties with the maximum quantum state (λ) and the temperature parameter (β) respectively, were studied. Using the molecular spectroscopic parameters, the Rydberg–Klein–Rees (RKR) of cesium dimer and lithium dimer were both obtained and compared with the experimental values. The RKR values of both cesium dimer and lithium dimer calculated aligned with the observed values. The deviation and average deviation of the RKR for each molecule were also calculated.

Ignition and flame quenching of quiescent fuel mists

1978 ◽  
Vol 364 (1717) ◽  
pp. 277-294 ◽  
Keyword(s):  
Reaction Rates ◽  
Ignition Energy ◽  
Minimum Ignition Energy ◽  
Proposed Model ◽  
Theoretical Predictions ◽  
Quenching Distance ◽  
Experimental Values ◽  
Sole Criterion ◽  
Fuel Vapour ◽  
Level Of Agreement

A model is proposed for the ignition of quiescent multidroplet fuel mists which assumes that chemical reaction rates are infinitely fast, and that the sole criterion for successful ignition is the generation, by the spark, of an adequate concentration of fuel vapour in the ignition zone. From analysis of the relevant heat transfer and evaporation processes involved, ex­pressions are derived for the prediction of quenching distance and minimum ignition energy. Support for the model is demonstrated by a close level of agreement between theoretical predictions of minimum ignition energy and the corresponding experimental values obtained using a specially designed ignition apparatus in which ignition energies are measured for several different fuels, over wide ranges of pressure, mixture composition and mean drop size. The results show that both quenching distance and mini­mum ignition energy are strongly dependent on droplet size, and are also dependent, but to a lesser extent, on air density, equivalence ratio and fuel volatility. An expression is derived to indicate the range of drop sizes over which the proposed model is valid.

scholarly journals The 7Be(p, ?)8B Cross Section at Low Energies

1980 ◽  
Vol 33 (2) ◽  
pp. 177 ◽  
Author(s):  
FC Barker
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Solar Neutrinos ◽  
Model Calculations ◽  
Spectroscopic Factors ◽  
Low Energies ◽  
Standard Values ◽  
Experimental Values ◽  
Parameter Values ◽  
Potential Parameters

The nonresonant part of the 7Be(p, )I)8B cross section at low energies is recalculated by means of a direct-capture potential model, using parameter values determined by fitting 7Li(n, n)7Li and 7Li(n, )I)8Li data. Standard values of the potential parameters and spectroscopic factors give values of the 7Li(n,)I) cross section that are too large. Modified values that fit the thermal-neutron capture cross section predict 7Be(p,)I) cross sections that are much less than the experimental values. Also, shell model calculations predict resonant 7Be(p,)I) cross sections that are smaller than the experimental values. It is suggested that the accepted experimental values of the 7Be(p, )I) cross section may be too large, perhaps due partly to an overlarge accepted value for the 7Li(d, p)8Li cross section, which has been used for normalization purposes. A decrease in the 7Be(p,)I) cross section would reduce the calculated detection rate of solar neutrinos and lessen the discrepancy with the measured value.

scholarly journals Extension of mathematical background for Nearest Neighbour Analysis in three-dimensional space

2013 ◽  
Vol 11 ◽  
pp. 25-36
Author(s):  
Eva Stopková
Keyword(s):  
Dimensional Space ◽  
Average Distance ◽  
Three Dimensional ◽  
Nearest Neighbour ◽  
Mathematical Background ◽  
Area Of Interest ◽  
Nearest Neighbours ◽  
Anisotropic Function ◽  
Neighbour Analysis ◽  
Three Dimensional Space

Proceeding deals with development and testing of the module for GRASS GIS [1], based on Nearest Neighbour Analysis. This method can be useful for assessing whether points located in area of interest are distributed randomly, in clusters or separately. The main principle of the method consists of comparing observed average distance between the nearest neighbours r A to average distance between the nearest neighbours r E that is expected in case of randomly distributed points. The result should be statistically tested. The method for two- or three-dimensional space differs in way how to compute r E . Proceeding also describes extension of mathematical background deriving standard deviation of r E , needed in statistical test of analysis result. As disposition of phenomena (e.g. distribution of birds’ nests or plant species) and test results suggest, anisotropic function would repre- sent relationships between points in three-dimensional space better than isotropic function that was used in this work.

The Perception of Minimal Structures: Performance on Open and Closed Versions of Visually Presented Euclidean Travelling Salesperson Problems

Perception ◽  
10.1068/p3416 ◽  
2003 ◽  
Vol 32 (7) ◽  
pp. 871-886 ◽  
Author(s):  
Douglas Vickers ◽  
Pierre Bovet ◽  
Michael D Lee ◽  
Peter Hughes
Keyword(s):  
Minimal Length ◽  
Nearest Neighbour ◽  
Optimal Solutions ◽  
Response Uncertainty ◽  
Structure And Motion ◽  
Nearest Neighbours ◽  
And Performance ◽  
Computational Intractability ◽  
Travelling Salesperson Problem

The planar Euclidean version of the travelling salesperson problem (TSP) requires finding a tour of minimal length through a two-dimensional set of nodes. Despite the computational intractability of the TSP, people can produce rapid, near-optimal solutions to visually presented versions of such problems. To explain this, MacGregor et al (1999, Perception28 1417–1428) have suggested that people use a global-to-local process, based on a perceptual tendency to organise stimuli into convex figures. We review the evidence for this idea and propose an alternative, local-to-global hypothesis, based on the detection of least distances between the nodes in an array. We present the results of an experiment in which we examined the relationships between three objective measures and performance measures of optimality and response uncertainty in tasks requiring participants to construct a closed tour or an open path. The data are not well accounted for by a process based on the convex hull. In contrast, results are generally consistent with a locally focused process based initially on the detection of nearest-neighbour clusters. Individual differences are interpreted in terms of a hierarchical process of constructing solutions, and the findings are related to a more general analysis of the role of nearest neighbours in the perception of structure and motion.

THE MICROWAVE SPECTRUM OF DICHLOROFLUOROMETHANE

1964 ◽  
Vol 42 (4) ◽  
pp. 720-730 ◽  
Author(s):  
David B. McLay
Keyword(s):  
Bond Length ◽  
Hyperfine Structure ◽  
Charge Distribution ◽  
Tensor Component ◽  
Microwave Spectrum ◽  
Frequency Range ◽  
Rotational Constants ◽  
Coupling Tensor ◽  
Quadrupole Coupling ◽  
Out Of Plane

The microwave spectra of C12HFCl235 and C12HFCl35Cl37 have been measured in the frequency range from 10 to 35 Gc/s. Enough R branch and Q branch rotational transitions have been measured in each case to determine the rotational constants A = 6988.73 ± 0.02, B = 3307.25 ± 0.05, and C = 2350.03 ± 0.02 Mc/s for CHFCl235 and A = 6943.37 ± 0.05, B = 3219.58 ± 0.04, and C = 2300.57 ± 0.06 Mc/s for CHFCl35Cl37. The out-of-plane coordinate of Cl35 in the symmetric species has been deduced to be 1.4350 ± 0.0006 Å and, if the C–Cl bond length is assumed to be 1.750 ± 0.005 Å, then the Cl–C–Cl angle can be calculated to be 112.2 ± 0.5°. The analysis of the hyperfine structure has led to the values eQVaa = −41.0 ± 0.2 Mc/s, eQVbb = +11.37 ± 0.13 Mc/s, and eQVcc = 29.62 ± 0.13 Mc/s for the diagonal components of the quadrupole coupling tensor along the principal inertial axes. The results are consistent with a cylindrically symmetrical charge distribution around the C–Cl bond and a quadrupole coupling tensor component of eQVzz = −76.75 Mc/s in the direction of the bond. The only impurity in the sample, obtained from the Matheson Company, seems to have been a trace of HCCF for which the J = 0 → 1 transition has been measured.

scholarly journals The Rotational Zeeman Effect in Fluorobenzene and the Molecular Quadrupole Moment in Benzene

1982 ◽  
Vol 37 (10) ◽  
pp. 1165-1175 ◽  
Author(s):  
W. H. Stolze ◽  
M. Stolze ◽  
D. Hübner ◽  
D. H. Sutter
Keyword(s):  
Magnetic Susceptibility ◽  
Carbon Tetrachloride ◽  
Quadrupole Moment ◽  
Ring Current ◽  
Zeeman Effect ◽  
Electric Quadrupole ◽  
Quadrupole Moments ◽  
Electric Quadrupole Moment ◽  
Microwave Spectrometer ◽  
Out Of Plane

The rotational Zeeman effect in fluorobenzene is reinvestigated with a resolution improved by a factor of almost five to give more accurate g-tensor elements, magnetic susceptibility anisotropics and molecular electric quadrupole moments. The results fit into the pictures of a linear dependence of the out of plane molecular electric quadrupole moment, Qcc, on the number of fluorine substituents and of a linear correlation between the nonlocal (ring current) susceptibility, Χccnonlocal, and the CNDO/2-π-electron density alternation. They lead to a gasphase molecular electric quadrupole moment in benzene, Qcc,benzene = - (28.4 ± 4.7) · 10-40 Cm2 which is slightly less negative than the value deduced from electric field-gradient birefringence experiments on dilute benzene solutions with carbon tetrachloride as solvent. A detailed description of the high resolution microwave spectrometer is given in the appendix.

AN INTERPRETATION OF THE LOW-LYING EXCITED STATES OF Mg25 AND Al25

1958 ◽  
Vol 36 (3) ◽  
pp. 378-404 ◽  
Author(s):  
A. E. Litherland ◽  
H. McManus ◽  
D. A. Bromley ◽  
H. E. Gove ◽  
E. B. Paul
Keyword(s):  
Excited States ◽  
Ground State ◽  
Salient Feature ◽  
Negative Parity ◽  
State Transitions ◽  
Rotational Model ◽  
Rotational States ◽  
Γ Ray ◽  
Deuteron Stripping ◽  
Experimental Values

A description of the experimental results obtained for Mg25 and Al25 is given based upon the assumption that the excited nuclear states are rotational states. In Mg25 and Al25 members of four rotational bands can be identified. The band based on the ground state can be assigned K = 5/2 whilst the three excited-state bands, two positive parity and one negative parity, can be assigned K = 1/2. The dipole γ-ray transitions between the K = 1/2 bands and the ground state K = 5/2 band are forbidden on the rotational model and it is a salient feature of the γ-ray cascading in Mg25 and Al25 that the ground-state transitions are always amongst the weakest transitions from excited states assigned to K = 1/2 bands. Besides giving a quantitative account of the γ-ray decay of the excited states the rotational model also predicts the number and type of the bands observed. The experimental values of the Mg24(d, p)Mg25 deuteron stripping reduced widths can also be approximately predicted by the model.

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