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Articles 34771 - 34800 of 36535

Full-Text Articles in Physical Sciences and Mathematics

Homogeneous Nucleation Of Ethanol, John L. Schmitt, G. W. Adams, R. A. Zalabsky Jan 1982

Homogeneous Nucleation Of Ethanol, John L. Schmitt, G. W. Adams, R. A. Zalabsky

Physics Faculty Research & Creative Works

The authors have used an expansion cloud chamber to measure homogeneous nucleation rate as a function of temperature and supersaturation in ethanol. Nucleation rates from 102 to 105 drops/cm3 sec were measured in the temperature range 252-272 °K. An empirical functional fit to the data is used to extrapolate for comparison with other data in the literature at a nucleation rate of 1 drop/cm3 sec and to compare with the predictions of the classical Becker-Doring homogeneous nucleation theory. A full listing of the data and thermodynamics constants used in the reduction of the data is given in an appendix. © …

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A Laser Interferometric Study Of Electric Field Effects On Methane-Oxygen Flame Plasmas, Mark D. Prairie Jan 1982

A Laser Interferometric Study Of Electric Field Effects On Methane-Oxygen Flame Plasmas, Mark D. Prairie

Masters Theses

A laser interferometer is developed to study the refractive index field, aerodynamic structure, and three dimensional temperature profile of a methane-oxygen flame system under the influence of D.C. electric fields. A combined graphical-numerical method is used to transform the observed interference patterns into radial temperature distributions. The results indicate that the electric field exerts a marked influence on the flame stability, geometry, and charged particle flow. Experimental evidence shows that these effects are most apparent under fuel rich conditions. It is suggested an electric field may change the concentration gradients of reacting species, leading to an altered course of fuel …

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Measurement Of The Wear Properties Of Metallic Solids With A Falex Lubricant Testing Machine, Edward Boyd Hale, Chun-Ping John Meng, Ronald A. Kohser Jan 1982

Measurement Of The Wear Properties Of Metallic Solids With A Falex Lubricant Testing Machine, Edward Boyd Hale, Chun-Ping John Meng, Ronald A. Kohser

Physics Faculty Research & Creative Works

A modified Falex Lubricant Testing Machine has been used to determine wear properties of metallic solids. In particular, wear mass loss, wear volume loss, wear rates, and other parameters have been determined for a basic steel, as heat treated and after ion implantation. Wear rate improvements of more than an order of magnitude were found in a nickel-chrome steel (SAE 3135) implanted with 2.5x1017 N+2/cm2. Wear tests were conducted with a cylinder-in-groove geometry in a mild lubricating oil with loads greater than 540 N, which corresponded to pressures which exceeded 108N/m2 …

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A Precision Measurement Of The Lifetime Of The Positive Muon, Kevin Louis Giovanetti Jan 1982

A Precision Measurement Of The Lifetime Of The Positive Muon, Kevin Louis Giovanetti

Dissertations, Theses, and Masters Projects

In an experiment performed at TRIUMF Laboratory, the time distribution of muon decay positrons arising from pions stopped in a water Cherenkov counter was measured with a high precision timing system. The pions served as a source of positive muons.;The data were used to determine a new value for the positive muon lifetime. This lifetime 2.19695 (+OR-) .00006 (sec) is slightly lower than previous measurements but still in fair agreement. The data were tested for the various systematic effects that typically occur in these measurements.

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Diffusion And Trapping Of Positive Muons In Niobium And In Aluminum Alloys, Muhammad Zillulhaq Numan Jan 1982

Diffusion And Trapping Of Positive Muons In Niobium And In Aluminum Alloys, Muhammad Zillulhaq Numan

Dissertations, Theses, and Masters Projects

Zero, longitudinal and transverse magnetic field uSR has been used to investigate (mu)('+) diffusion and trapping in Nb. The ambiguity in the interpretation of the 'double humped' temperature dependence of the depolarisation rate for the transverse field case has been resolved. A discussion of how the zero and longitudinal measurements can distinguish between the trapping and detrapping phenomena is presented with (mu)SR data analysis in mind. Muon mobility is shown to increase monotonically with temperature. The width of the local magnetic field distribution due to Nb nuclear moments and the rate for trapping and detrapping of muons have been measured …

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Experimental Studies Of Antiprotonic Atoms In Hydrogen And Helium, Jeffrey Robert Lindenmuth Jan 1982

Experimental Studies Of Antiprotonic Atoms In Hydrogen And Helium, Jeffrey Robert Lindenmuth

Dissertations, Theses, and Masters Projects

In an experiment performed at Brookhaven National Laboratory the spectra of atomic x rays from stopped antiprotons in gaseous helium, liquid hydrogen, and gaseous hydrogen were measured. The measurements were performed at 1 atmosphere and 25(DEGREES)K for the gaseous target.;In the case of He the L and M series of p were observed and relative intensities measured. However in hydrogen no x rays were observed and thus only an upper limit of the yields of the K series in liquid and gaseous hydrogen were calculated.

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A [Mu]+Srstudy Of Uniaxial Stress Induced Symmetry Breaking In An Fe Single Crystal, Min. Namkung Jan 1982

A [Mu]+Srstudy Of Uniaxial Stress Induced Symmetry Breaking In An Fe Single Crystal, Min. Namkung

Dissertations, Theses, and Masters Projects

For the first time, external uniaxial stress has been used in a (mu)('+)SR experiment. The stress dependences of the following parameters were obtained for Fe crystals: the muon precessional frequency, (nu)(,(mu)), the transverse (longitudinal) depolarization rates, 1/T(,2) (1/T(,1)), and F(,T)/F(,L), the ratio of the probabilities for the muon to find domains with transverse/longitudinal fields. The shift in (nu)(,(mu)) was -0.34 (+OR-) 0.023 MHz per 100 micro-strain along the -axis. Changes in other parameters depend on the sample history but they, in general, increase with stress.;External stress changes the muon occupational probability at each site which significantly affects the dipolar field …

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Anisotrophy In Mhd Turbulence Due To A Mean Magnetic Field, John V. Shebalin Jan 1982

Anisotrophy In Mhd Turbulence Due To A Mean Magnetic Field, John V. Shebalin

Dissertations, Theses, and Masters Projects

The development of anisotropy in an initially isotropic spectrum is studied numerically for two-dimensional magnetohydrodynamic (MHD) turbulence. The anisotropy develops due to the combined effects of an externally imposed dc magnetic field and viscous and resistive dissipation at high wave numbers. The effect is most pronounced at high mechanical and magnetic Reynolds numbers. The anisotropy is greater at the higher wave numbers.;The statistical structure of two-dimensional MHD turbulence is also considered. It is shown that the three known rugged invariants of the isotropic case reduce to two for the anisotropic case. Randomness and ergodicity are also briefly discussed.

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Y Expansion For Directed Lattice Animals, Anthony Day, T. Lubensky Dec 1981

Y Expansion For Directed Lattice Animals, Anthony Day, T. Lubensky

Anthony Roy Day

No abstract provided.

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Path-Integrals And The Wkb Approximation, Br Holstein, Ar Swift Dec 1981

Path-Integrals And The Wkb Approximation, Br Holstein, Ar Swift

Barry R Holstein

The WKB approximation is demonstrated to be formally identical to the semiclassical limit of the Feynman path integral propagator. In the limit that the path integral propagator is dominated by the classical particle trajectory, it is identical to the propagator calculated directly from WKB wave functions in the stationary phase approximation.

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Contours Of Constant Principal Angle And Constant Principal Azimuth In The Complex Ε Plane, R. M.A. Azzam Dec 1981

Contours Of Constant Principal Angle And Constant Principal Azimuth In The Complex Ε Plane, R. M.A. Azzam

Electrical Engineering Faculty Publications

For light reflection at a planar interface between two homogeneous isotropic media with complex relative dielectric function ε, we show that the constant-principal-angle contours are a family of semicircles, whereas the constantprincipal-azimuth contours are a family of (segments of) hyperbolas in the complex ε plane. We also find the exact envelope curve of both families and hence determine the domain of the ε plane of multiple (three) principal angles that is bougded by the envelope curve and the real axis. A unique and peculiar interface with ε = (5 - j√2)/27 is shown to have three coincident principal angles of …

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Hot-Wire Anemometer Behaviour In Low Velocity Air Flow, P. J. Christman, Josef Podzimek Dec 1981

Hot-Wire Anemometer Behaviour In Low Velocity Air Flow, P. J. Christman, Josef Podzimek

Physics Faculty Research & Creative Works

The behavior characteristics of a commercially available hot-wire anemometer have been examined in the presence of low velocities, lwss than 0.1 m/s for the most part, and in both horizontal and vertical air flows. The orientation of the probe in a horizontal flow has been found to have a definite effect on velocity measurements, and a lower limit to the reliable application of hot-wire anemometry has been evaluated for a particular type of probe. Vertical flow measurements have resulted in the discovery of the magnitude of natural convective velocity, and a possible method for determining the dimensions of the temperature …

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Reply (To "Comment On 'The Absolute Scattering Cross Section At50 Mhz Of Equatorial Electrojet Irregularities' By Farley Et Al." By N. D'Angelo), D. T. Farley, Bela G. Fejer Dec 1981

Reply (To "Comment On 'The Absolute Scattering Cross Section At50 Mhz Of Equatorial Electrojet Irregularities' By Farley Et Al." By N. D'Angelo), D. T. Farley, Bela G. Fejer

Bela G. Fejer

No abstract provided.

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Precision Expansion Cloud Chamber For Homogeneous Nucleation Studies, John L. Schmitt Dec 1981

Precision Expansion Cloud Chamber For Homogeneous Nucleation Studies, John L. Schmitt

Physics Faculty Research & Creative Works

The author describes an expansion cloud chamber for the study of the nucleation of a single component vapor (homogeneous nucleation). The design draws on the many years of experience in this Center in construction of chambers for homogeneous nucleation of water. Design features of the chamber are exact control of temperature (±0.03° C), pressure (±0.5 mm Hg), and automatic control of cycling. Construction features are all construction materials are stainless steel, glass, or fluorocarbon plastics; the piston seal is a very flexible welded stainless-steel bellows; the chamber can be made very clean by heating under vacuum, and it is compatible …

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Suitability Of Egyptian Raw Materials For The Production Of Cement Clinker Using The Dry Process, Lamia Rifaat Ismail Dec 1981

Suitability Of Egyptian Raw Materials For The Production Of Cement Clinker Using The Dry Process, Lamia Rifaat Ismail

Archived Theses and Dissertations

No abstract provided.

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Crystal Perfection Of Hgi2 Studied By Neutron And Gamma-Ray Diffraction, W. (William) B. Yelon, R. W. Alkire, M. M. Schieber, L. Van Den Berg, S. E. Rasmussen, H. Christensen, J. R. Schneider Dec 1981

Crystal Perfection Of Hgi2 Studied By Neutron And Gamma-Ray Diffraction, W. (William) B. Yelon, R. W. Alkire, M. M. Schieber, L. Van Den Berg, S. E. Rasmussen, H. Christensen, J. R. Schneider

Physics Faculty Research & Creative Works

The crystalline perfection of wire sawn pieces of vapor grown single crystals of mercuric iodide was compared with the perfection of (00l) cleaved sections of the same crystal from which nuclear radiation detectors have been fabricated. The crystalline perfection was studied using neutron and gamma-ray diffraction rocking curves. Most of the gamma-ray data were obtained using a high intensity source of 153Sm gamma rays with a wavelength of λ = 0.12 Å. Some of the data were obtained using highly penetrating 198Au gamma rays with a shorter wavelength of λ = 0.03 Å. The neutrons had a wavelength of λ …

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Bilinear Equation For The Cylinder With Overlap And The Pomeron Residue, Paul Finkler, C. Edward Jones Nov 1981

Bilinear Equation For The Cylinder With Overlap And The Pomeron Residue, Paul Finkler, C. Edward Jones

Paul Finkler Papers

A bilinear integral equation for the cylinder is derived within the meson sector of the theory of dual topological unitarization. The equation is more general than conventional linear cylinder equations since it includes regions of phase space in which produced particles overlap in rapidity. The equation also permits a simple treatment of phase space which corresponds to that of the planar bootstrap problem. Two classes of solutions are found, only one of which results in the Pomero'n-f identity. This treatment also indicates that the residue of the Pomeron may be twice as large as that suggested by earlier calculations …

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Miiiikan Award For 1981, Robert Fuller Nov 1981

Miiiikan Award For 1981, Robert Fuller

Robert G. Fuller Publications

In conclusion, for his notable and creative contributions to physics teaching, in particular how he has alerted us to the implications of our cultural assumptions, how he has found interesting physics everywhere, and how he has valued the humanity of physics, the American Association of Physics Teachers presents to Albert A. Bartlett the 1981 Robert A. Millikan Award.

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Magnetic And Electrical Properties Of Iron-Nickel-Chromium-Metalloid Glasses, H. Sadate-Akhavi, George C. Hadjipanayis, David J. Sellmyer Nov 1981

Magnetic And Electrical Properties Of Iron-Nickel-Chromium-Metalloid Glasses, H. Sadate-Akhavi, George C. Hadjipanayis, David J. Sellmyer

David Sellmyer Publications

The magnetic and electrical properties of amorphous (Fe1-xNix)78-yCrySi10B12 alloys have been measured between 4.2 and 300 K. Alloys with x≤0.9 and y=5 order ferromagnetically. High-field magnetization measurements show saturation in moderate fields suggesting a relatively high value of magnetic anisotropy which was estimated to be K≃106 erg/cm3. The magnetization at low temperatures follows a T3/2 law leading to a spin-wave stiffness coefficient D≃90 meV Å2. The x=1, y=5 alloy behaves like a "cluster glass" with a cluster ordering temperature around 20 …

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Statistics Of Multicharge Centers In Semiconductors - Applications, David C. Look Nov 1981

Statistics Of Multicharge Centers In Semiconductors - Applications, David C. Look

Physics Faculty Publications

A general formula is derived for the electron occupation numbers appropriate for multicharge centers in semiconductors, including excited states. The results are used to rederive and generalize several formulas of interest in the literature, in order to show exactly how the degeneracies of individual states enter in. Particular attention is paid to certain subjects which are sometimes confusing, such as how the statistics of band states differ from those those of localized states. Another subject of much recent interest, negative-U centers, is dealt with in some detail. We show how the dependence of the average occupation number on Fermi …

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Massive Neutrinos And The Stellar Stopping Power Via The Neutrino Magnetic Moment, P.T. Leung, M. L. Rustgi, J. E. Turner, Werner Brandt Nov 1981

Massive Neutrinos And The Stellar Stopping Power Via The Neutrino Magnetic Moment, P.T. Leung, M. L. Rustgi, J. E. Turner, Werner Brandt

Physics Faculty Publications and Presentations

An exact expression is derived within the high-Q approximation for the spectrum of energy losses of neutrinos interacting via their magnetic moment with electrons. A formula for the stopping power of matter for neutrinos is derived and applied to the study of the solar neutrino anomaly. The total inelastic cross section is given. An upper limit is deduced for the neutrino magnetic moment from the antineutrino spectrum as recently parameterized by Lee (1979). It confirms the bound reported by Cowan and Reines. The distance for stellar neutrinos to thermalize by the interactions studied here, through encounters with stars is found …

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Explicit Determination Of Thickness Of A Transparent Film On A Transparent Substrate From Angles Of Incidence Of Equal P And S Reflectivities, R. M.A. Azzam Oct 1981

Explicit Determination Of Thickness Of A Transparent Film On A Transparent Substrate From Angles Of Incidence Of Equal P And S Reflectivities, R. M.A. Azzam

Electrical Engineering Faculty Publications

No abstract provided.

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Orientation Of Atoms Excited By Charged Particles At High Impact Energies, Don H. Madison, Kieth H. Winters Oct 1981

Orientation Of Atoms Excited By Charged Particles At High Impact Energies, Don H. Madison, Kieth H. Winters

Physics Faculty Research & Creative Works

A perturbation-expansion approach is used to examine the sign of the orientation vector as a function of scattering angle and projectile charge. It is shown that for small angles, the sign of the orientation vector is different for oppositely charged projectiles consistent with the prediction of the classical grazing model. At large angles, on the other hand, the orientation vector for oppositely charged projectiles is shown to have the same sign.

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Existence Of The Dielectric Constant In Dipolar Fluid Mixtures, John D. Ramshaw, Norman D. Hamer Oct 1981

Existence Of The Dielectric Constant In Dipolar Fluid Mixtures, John D. Ramshaw, Norman D. Hamer

Physics Faculty Publications and Presentations

The existence of the dielectric constant epsilon is investigated for fluid mixtures of rigid polar molecules. The investigation is performed using the functional-derivative formalism for mixtures, and is closely analogous to that previously carried out for pure dipolar fluids (J. Chem. Phys. 68, 5199 (1978)). Sufficient conditions for the existence of epsilon are obtained in terms of the direct correlation function matrix c/sub alphabeta/(12). It is found that epsilon exists if c/sub alphabeta/(12) depends only on relative positions and orientations, and becomes asymptotic to -theta/sub alphabeta/(12)/kT at long range, where theta/sub alphabeta/(12) is the dipole--dipole potential between a molecule of …

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Glory In Optical Backscattering From Air Bubbles, Dean S. Langley, Philip L. Marston Sep 1981

Glory In Optical Backscattering From Air Bubbles, Dean S. Langley, Philip L. Marston

Physics Faculty Publications

Observations of light backscattered from air bubbles in a viscous liquid demonstrate an enhancement due to axial focusing. A physical-optics approximation for the cross-polarized scattering correctly describes the spacing of regular features observed. The non-cross polarized scattering is not adequately described by a single class of rays.

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The Absolute Scattering Cross Section At 50 Mhz Ofequatorial Electrojet Irregularities, D. T. Farley, H. M. Ierkic, Bela G. Fejer Sep 1981

The Absolute Scattering Cross Section At 50 Mhz Ofequatorial Electrojet Irregularities, D. T. Farley, H. M. Ierkic, Bela G. Fejer

Bela G. Fejer

We have made carefully calibrated radar scattering measurements by using the large 50-MHz Jicamarca antenna. Typical results from the altitudes of maximum echo power for the vertically directed beam are σradar ∼1–2 × 10−10 m−1 for strong daytime electrojet conditions with type 1 irregularities present, with values a factor of 10 or so smaller during moderate conditions when only type 2 are observed. These cross sections, which are very large in comparison with those for incoherent scatter (σradar ≃5 × 10−18 m−1 for an electron density of 1011 m−3), are not nearly large enough, however, to cause pseudo-absorption events on …

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Optical Pulse Compression In A Cholesteric Liquid Crystal, D. N. Ghosh Roy, D.V.G.L.N. Rao, H. Bronk Sep 1981

Optical Pulse Compression In A Cholesteric Liquid Crystal, D. N. Ghosh Roy, D.V.G.L.N. Rao, H. Bronk

Physics Faculty Publications

A 20‐ns laser pulse is compressed to nearly 2.5 ns in a 10‐cm‐long sample of liquid‐crystal cholesteryl oleate in the isotropic phase. Pulse compression in a length as short as only 5 cm has been observed. A semiquantitative explanation is given in terms of stimulated Brillouin scattering.

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Theoretical Study Of The Structural Phase Transition In Rbcaf3, L. L. Boyer, John R. Hardy Sep 1981

Theoretical Study Of The Structural Phase Transition In Rbcaf3, L. L. Boyer, John R. Hardy

John R. Hardy Papers

We have made a first-principles study of the structural phase transition at Tc = 193 K in RbCaF3, using interionic potentials derived by the Gordon-Kim approach, and a new extension of the quasiharmonic approximation for the free energy. The transition is caused by instability of a triply degenerate R-point vibration which leads to a coordinated rotation of the CaF6 octahedra. We find that, as the lattice contracts, the quasiharmonic frequency of the R-point vibrations becomes imaginary at approximately 1280 K: Below this temperature the static lattice energy, as a function of CaF6 rotation, has a …

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Time-Dependent Direct Correlation Function, John D. Ramshaw Sep 1981

Time-Dependent Direct Correlation Function, John D. Ramshaw

Physics Faculty Publications and Presentations

A time-dependent direct correlation function (TDDCF) is defined and discussed. The definition (which differs from that proposed by Percus and Yevick) is motivated by linear response theory. The TDDCF consequently has a functional-derivative or stimulus-response interpretation closely analogous to that of the static direct correlation function. Mean-field considerations suggest that the TDDCF separates into a term which is simply related to the pair potential and a spatially shorter-ranged remainder. This behavior is confirmed in the Vlasov-Zwanzig approximation.

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23rd Rocky Mountain Conference Aug 1981

23rd Rocky Mountain Conference

Rocky Mountain Conference on Magnetic Resonance

Abstracts and meeting program from the 23rd annual meeting of the Rocky Mountain Conference, co-sponsored by the Rocky Mountain Section of the Society for Applied Spectroscopy and the Rocky Mountain Chromatography Discussion Group. Held in Denver, Colorado, August 2-6, 1981.

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