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Articles 6511 - 6534 of 6534

Full-Text Articles in Physical Sciences and Mathematics

Rayleigh Hysteresis Shape: Its Relationship To Displacement Distance Of A Single Domain Wall In 50% Ni–Fe, R. C. Woodbury, M. R. Hunt Mar 1970

Rayleigh Hysteresis Shape: Its Relationship To Displacement Distance Of A Single Domain Wall In 50% Ni–Fe, R. C. Woodbury, M. R. Hunt

Faculty Publications

The need to measure the displacement distance of domain walls from equilibrium for very weak alternating fields (H ≪ coercive force) in bulk magnetic material has prompted a study of the possible use of the opening of the Rayleigh hysteresis loop to indicate the amount of wall displacement. This paper contains (1) a review of the theoretical relationship between hysteresis shape and the displacement distance of a domain wall, based upon defect-energy models of Rodbell and Bean, and Baldwin; and (2) an experimental approach which provides a measure of the wall displacements versus hysteresis shape for 50% Ni–Fe tape. Discrepancies …

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Ua11/2 Planetarium Program To Describe The Moon In February Sessions, Wku Public Affairs Feb 1970

Ua11/2 Planetarium Program To Describe The Moon In February Sessions, Wku Public Affairs

WKU Archives Records

Press release entitled: Planetarium Program to Describe the Moon in February Sessions.

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Proposed Thermodynamic Pressure Scale For An Absolute High-Pressure Calibration, Daniel L. Decker, J. Dean Barnett Feb 1970

Proposed Thermodynamic Pressure Scale For An Absolute High-Pressure Calibration, Daniel L. Decker, J. Dean Barnett

Faculty Publications

The field of high pressure has developed rapidly over the past few years to a point where relatively sophisticated experiments are being attempted. In many experiments it is no longer sufficient to qualitatively estimate the pressure or to base conclusions on experimental results tied to an empirical pressure parameter. One desires to accurately know the pressure dependence of physical quantities related to a true thermodynamic scale.

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New Solutions Of The Einstein-Maxwell Equations From Old, B. Kent Harrison Nov 1968

New Solutions Of The Einstein-Maxwell Equations From Old, B. Kent Harrison

Faculty Publications

Methods are discussed with which one may derive theorems which allow one to generate new solutions of the Einstein-Maxwell equations from old ones. The old solutions used to generate new ones must admit at least one nonnull Killing vector and may be required to satisfy other conditions, depending on the theorem derived. Examples of derivable theorems are shown; these theorems are used in turn to show how generation of new solutions is accomplished. Examples of the latter are shown, such as generation of Brill or electrified NUT space from the Schwarzschild solution, generation of a new twisted Melvin universe from …

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"Planetary Exploration (Lecture Two)", Carl Sagan Mar 1968

"Planetary Exploration (Lecture Two)", Carl Sagan

Special Collections: Oregon Public Speakers

Requested by: "Standing order from Science" "Planetary Exploration"

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"Planetary Exploration (Lecture One)", Carl Sagan Mar 1968

"Planetary Exploration (Lecture One)", Carl Sagan

Special Collections: Oregon Public Speakers

No abstract provided.

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A Method For Measuring Magnetization To High Pressures, C. R. Johansen, Mark H. Nelson, J. H. Gardner Mar 1968

A Method For Measuring Magnetization To High Pressures, C. R. Johansen, Mark H. Nelson, J. H. Gardner

Faculty Publications

A partially successful attempt has been made to measure the magnetic moment per unit volume of ferromagnetic materials as a function of pressure to the 100-kbar region. The apparatus, an early version of which has been described previously, consists basically of two opposed Bridgman flat anvils of alumina. One anvil also acts as a dielectric-filled microwave resonant cavity for an x-band spectrometer, allowing electron spin resonance studies to be made to high pressure. The sample to be studied is placed in contact with the anvil-cavity and covered with a pressure-transmitting medium which in turn is encircled by a flat pyrophyllite …

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Very High Pressure Effects Upon The Epr Spectrum Of Ruby, H. Mark Nelson, D. B. Larson, J. H. Gardner Sep 1967

Very High Pressure Effects Upon The Epr Spectrum Of Ruby, H. Mark Nelson, D. B. Larson, J. H. Gardner

Faculty Publications

The variation in the electron paramagnetic resonance (EPR) spectrum of ruby as a function of pressure has been observed to beyond 70 kbar for a magnetic field orientation parallel to the crystalline c axis. The data can be interpreted in terms of the usual spin Hamiltonian, where the spectroscopic splitting factor g|| has the same value as at ambient pressures, but where the zero-field splitting deltaincreases in a linear fashion from 0.38 to 0.43 cm. The experimental apparatus has been described previously, although important improvements in the pressure seal and in the pressure calibration have been made and are described …

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Equation Of State Of Sodium Chloride, Daniel L. Decker Dec 1966

Equation Of State Of Sodium Chloride, Daniel L. Decker

Faculty Publications

Because of many requests, I wish to publish the following numerical table of results for the equation of state of NaCl as calculated in an earlier paper1 along with a few comments on various proposed equations for NaCl. Table I gives the pressure in kilobars at the corresponding values of t.a/ao and temperature in the appropriate row and column. The parameter t.a/ao is the fractional compression of the lattice parameter where the standard value ao is the appropriate lattice parameter at zero pressure and 25°C. The increments between the values given in the table were chosen such that one can …

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Model Of Electron Correlation In Solids, Everett G. Larson, Walter R. Thorson Sep 1966

Model Of Electron Correlation In Solids, Everett G. Larson, Walter R. Thorson

Faculty Publications

The usual Hartree-Fock model (energy-band theory) does not always give an adequate description of electronic structure in a solid, because it ignores the effects of electron correlation. It was shown first by Wigner that such a situation always develops in an electron ''gas'' at sufficiently low density; a solid structure described by ''resonance'' of Heitler-London pair bonds between electrons localized on neighboring atoms is then a good model of the system.The transition from a Bloch-type state to such a highly correlated state as a function of electron density (lattice parameter) is a problem of considerable interest for the theory of …

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Pressure Calibration To 100 Kbar Based On The Compression Of Nacl, R. N. Jeffrey, J. Dean Barnett, H. B. Vanfleet, H. Tracy Hall Jul 1966

Pressure Calibration To 100 Kbar Based On The Compression Of Nacl, R. N. Jeffrey, J. Dean Barnett, H. B. Vanfleet, H. Tracy Hall

Faculty Publications

An independent determination has been made of the transformation pressures assigned to the high-pressure transformations in Ba and Bi which are generally used for calibration points. The metals were imbedded in NaCl, and the transitions were detected by the resistance change of the metal while the NaCl lattice parameter was simultaneously measured by x-ray diffraction. The NaCl compression values determined at the fixed points were related to pressure by reference to the semiempirical compression curve of Decker. The Ba I-II and Bi III-V transformations at room temperature were assigned thermodynamic equilibrium values of 53.3 ±1.2 kbar and 73.8 ±1.3 kbar, …

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X-Ray Diffraction Studies On Tin To 100 Kilobars, J. Dean Barnett, Vern E. Bean, H. Tracy Hall Feb 1966

X-Ray Diffraction Studies On Tin To 100 Kilobars, J. Dean Barnett, Vern E. Bean, H. Tracy Hall

Faculty Publications

The high-pressure equilibrium phase diagram of tin is investigated, and the crystal structure of Sn II at 98 kbar and 25degrees C is shown to be body-centered tetragonal with a=3.70 Angstroms, c=3.37 Angstroms, c/a=0.91, and with two atoms per unit cell. The linear compressibility of white tin is given at 25degrees C up to the high-pressure transformation at 92 kbar, and the latent heat of the transformation is measured as 225 cal/g-atom.

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Equation Of State Of Nacl And Its Use As A Pressure Gauge In High-Pressure Research, Daniel L. Decker Jan 1965

Equation Of State Of Nacl And Its Use As A Pressure Gauge In High-Pressure Research, Daniel L. Decker

Faculty Publications

The pressure as a function of lattice parameter and temperature has been calculated for NaCl over a pressure range of 0 to 500 kbar for temperatures between 0degrees and 1500degrees C. The calculation used the Mie-Gruneisen equation of state with Born-Mayer type repulsion terms between first and second nearest neighbors. The Gruneisen constant was expanded about its value at room temperature and atmospheric pressure; the first coefficient in the expansion being evaluated by forcing the calculated thermal expansion at atmospheric pressure to fit the experimental results of Enck. The two empirical parameters in the repulsion terms were evaluated using the …

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Solar Radiation, Gloucester Point, Virginia : [1960-1963], Bernard C. Patten, J. Ernest Warriner, Weston Eayrs, Charles L. Rutherford, D. K. Young, Richard B. Stone, Virginia Fisheries Laboratory Jan 1964

Solar Radiation, Gloucester Point, Virginia : [1960-1963], Bernard C. Patten, J. Ernest Warriner, Weston Eayrs, Charles L. Rutherford, D. K. Young, Richard B. Stone, Virginia Fisheries Laboratory

Reports

No abstract provided.

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Diffraction Of Spherical Scalar And Vector Waves At Axial Points Of A Circular Aperture And Disk, Keith Leon Mcdonald Jun 1962

Diffraction Of Spherical Scalar And Vector Waves At Axial Points Of A Circular Aperture And Disk, Keith Leon Mcdonald

Faculty Publications

The following work treats Kottler's saltus problem of diffraction of electromagnetic waves emitted by a Hertzian oscillator source and the analogous Kirchhoff's scalar problem of waves emitted by a point source. The medium is a homogeneous isotropic dielectric. In the vector case a new exact solution of the basic integrals is presented, at axial points only, (a) behind a circular aperture in a "black'' screen, and (b) behind its complementary "black'' disk. The relative time-averaged intensity of energy flow is plotted for the disk only. It is shown that the scalar theory predicts considerably larger values than the electromagnetic theory …

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A Note On K-Commutative Matrices, D. W. Robinson Nov 1961

A Note On K-Commutative Matrices, D. W. Robinson

Faculty Publications

Let A and B be square matrices over a field in which the minimum polynomial of A is completely reducible. It is shown that A is k commutative with respect to B for some non-negative integer k if and only if B commutes with every principal idempotent of A. The proof is brief, simplifying much of the previous study of k-commutative matrices. The result is also used to generalize some well-known theorems on finite matrix commutators that involve a complex matrix and its transposed complex conjugate.

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4. Kepler, Robert L. Bloom, Basil L. Crapster, Harold A. Dunkelberger, Charles H. Glatfelter, Richard T. Mara, Norman E. Richardson, W. Richard Schubart Jan 1958

4. Kepler, Robert L. Bloom, Basil L. Crapster, Harold A. Dunkelberger, Charles H. Glatfelter, Richard T. Mara, Norman E. Richardson, W. Richard Schubart

Section VIII: The Development of Modern Science

Tycho Brahe (1546-1601), a Dane, spent nearly his entire life making careful measurements of the positions of the stars and planets. Most of his work was done at Copenhagen under the patronage of the Danish king. He developed and refined astronomical instruments to an accuracy that was far superior to anything previously done. In his late years at Prague, he started on the reduction to order of the systematic observations that he had made over a period of decades. In 1600 a young German mathematician and astronomer, Johannes Kepler (1571-1630), visited Tycho and then stayed to help in the mammoth …

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2. Copernicus, Robert L. Bloom, Basil L. Crapster, Harold A. Dunkelberger, Charles H. Glatfelter, Richard T. Mara, Norman E. Richardson, W. Richard Schubart Jan 1958

2. Copernicus, Robert L. Bloom, Basil L. Crapster, Harold A. Dunkelberger, Charles H. Glatfelter, Richard T. Mara, Norman E. Richardson, W. Richard Schubart

Section VIII: The Development of Modern Science

Nicolaus Copernicus (1473-1543), of German and possibly Polish extraction, spent three years at the University of Cracow and then ten years at Italian universities. In Italy he was introduced to the Pythagorean ideas, which left a permanent mark on his mind, and became interested in astronomical theories. He returned home to the position of canon of Frauenburg cathedral where he stayed until his death. [excerpt]

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1. Greek And Medieval Science, Robert L. Bloom, Basil L. Crapster, Harold A. Dunkelberger, Charles H. Glatfelter, Richard T. Mara, Norman E. Richardson, W. Richard Schubart Jan 1958

1. Greek And Medieval Science, Robert L. Bloom, Basil L. Crapster, Harold A. Dunkelberger, Charles H. Glatfelter, Richard T. Mara, Norman E. Richardson, W. Richard Schubart

Section VIII: The Development of Modern Science

What kind of questions did the Greeks ask themselves about the physical universe? We can paraphrase Plato: the stars move about the earth in circles, the perfect paths, and they move with uniform motion as befits divine and eternal beings. But five of these stars are planets (Greek for wanderers) which appear to have irregular motion, first moving forward, then actually stopping, and then moving backward for awhile. Since the heavens are incorruptible, the planets too must really be moving in uniform motion in circular paths. How then can we account for the apparently irregular motions? What uniform motions must …

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Total Solar Eclipse, January 24, 1925, Halsey Dewolf Jan 1925

Total Solar Eclipse, January 24, 1925, Halsey Dewolf

Fulton/Howe Collection

On January 24, 1925, a total eclipse of the sun was visible throughout much of New England. This account, written by Halsey DeWolf, describes the eclipse as viewed from Watch Hill, Rhode Island.

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Ua94/6/2/7 Physiography Notebook, Carl Ellis Jan 1911

Ua94/6/2/7 Physiography Notebook, Carl Ellis

Student/Alumni Personal Papers

Atlas Science Table for Laboratory Notes and Drawings in Physiography notebook used by Carl Ellis for Robert Green's class.

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Ua94/6/2/14 Physiography Notebook, Annie Reis Jan 1910

Ua94/6/2/14 Physiography Notebook, Annie Reis

Student/Alumni Personal Papers

Physiography notebook kept by student Annie Reis in 1910. Notebook includes notes and drawings related to physical geography such as solar systems, rivers, faults, weather and glaciers.

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Some Contributions Of Pure Math To Science, Herbert B.E. Case Jan 1897

Some Contributions Of Pure Math To Science, Herbert B.E. Case

Student and Lippitt Prize essays

An examination of the connection between math and science through discoveries in the subjects of astronomy, mechanics, physics and chemistry.

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Comets And Meteors, Lincoln N. Oatley Jan 1895

Comets And Meteors, Lincoln N. Oatley

Student and Lippitt Prize essays

Defines and describes named comets and meteor events and their scientific study.

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