Open Access. Powered by Scholars. Published by Universities.®
- Discipline
-
- Engineering (1314)
- Physical Sciences and Mathematics (921)
- Education (400)
- Electrical and Computer Engineering (246)
- Social and Behavioral Sciences (227)
-
- Physics (214)
- Chemical Engineering (208)
- Materials Science and Engineering (207)
- Chemistry (198)
- Mechanical Engineering (192)
- Computer Sciences (190)
- Psychology (165)
- Mathematics (145)
- Civil and Environmental Engineering (138)
- Earth Sciences (135)
- Civil Engineering (108)
- Geology (99)
- Medicine and Health Sciences (95)
- Biomedical Engineering and Bioengineering (90)
- Geophysics and Seismology (86)
- Educational Leadership (78)
- Mining Engineering (70)
- Clinical Psychology (68)
- Operations Research, Systems Engineering and Industrial Engineering (67)
- Petroleum Engineering (64)
- Business (63)
- Nuclear Engineering (62)
- Arts and Humanities (60)
- Nanoscience and Nanotechnology (59)
- Geological Engineering (57)
- Institution
- Keyword
-
- Physics (208)
- Biology (201)
- Education (184)
- Chemistry (170)
- Psychology (151)
-
- Engineering (134)
- Sociology (100)
- General (99)
- Ecology (73)
- Environmental Sciences (69)
- Agriculture (64)
- Applied sciences (58)
- History (57)
- United States (53)
- Pure sciences (49)
- Organic (44)
- Astronomy and Astrophysics (43)
- Literature (43)
- Physical (43)
- Fluid and Plasma (41)
- Mathematics (40)
- Social (40)
- Zoology (40)
- Analytical (39)
- Genetics (38)
- Mechanical (38)
- Biochemistry (37)
- Microbiology (37)
- Women's Studies (32)
- Individual and Family Studies (31)
- Publication Year
- Publication Type
- File Type
Articles 5521 - 5550 of 5718
Full-Text Articles in Entire DC Network
Temperature Variation In Distribution Of Relaxation Times In Aluminosilicate Glasses, David Wayne Moore
Temperature Variation In Distribution Of Relaxation Times In Aluminosilicate Glasses, David Wayne Moore
Doctoral Dissertations
"The distribution of relaxation times for the alkali peak in a Li₂ O·A1₂O₃ ·2.0SiO₂ glass and for the mixed alkali peak in a 0.5Li₂O·0.5Na₂O·A1₂O₃·2.OSiO₂ glass was studied using the internal friction technique. A lognormal distribution of relaxation times provided the best agreement with the experimental data. The ß parameter of the lognormal distribution function, which is related to the half-height peak width, varied with temperature, indicating that the distribution of relaxation times is dependent upon the activation energy and the activation entropy of the relaxation mechanism. The major contributor to the distribution of relaxation times is a wide distribution in …
The Electrochemical Behavior Of The Lead-Thallium System In Acidic Sulfate Solutions, Pedro Juan Aragon
The Electrochemical Behavior Of The Lead-Thallium System In Acidic Sulfate Solutions, Pedro Juan Aragon
Doctoral Dissertations
"Although the literature involving the corrosion of pure lead in sulfuric acid solutions is extensive, such studies still constitute an active field of investigation and debate. Much of the effort expended on this subject is due to the need of a better understanding of the reaction in lead storage batteries as well as of the mode of electrocrystallization processes. The resistance of lead to attack by sulfuric acid renders it an important coating material in this media. It is also often used in electrochemical synthesis because of its overvoltage characteristics. Unfortunately its mechanical properties are poor, and many ways have …
The Surface Effects Of Alkali Halides In The Infrared, Vincent Joseph Llamas
The Surface Effects Of Alkali Halides In The Infrared, Vincent Joseph Llamas
Doctoral Dissertations
"The surface state extension of the shallow donor theory is reviewed. The surface state theory and its applications to F-centers of alkali halides is presented. Experimental infrared data show an absorption which seems to correspond with the ground state to first excited state transition. Surface state concentrations of F-centers as a function of depth into the crystal are given. The ratio of surface to bulk cross sections in KBr and experimental calculations of effective masses in various alkali halides are in excellent agreement with theory. The theoretical cross sections are derived from transition probabilities. However, lack of excited states, the …
MöSsbauer Effect Studies Of Ferroelectric Phase Transitions In The Pbzro₃ - Pbtio₃ - Bifeo₃ Ternary System, James P. Canner
MöSsbauer Effect Studies Of Ferroelectric Phase Transitions In The Pbzro₃ - Pbtio₃ - Bifeo₃ Ternary System, James P. Canner
Doctoral Dissertations
"The Mössbauer Effect was used to measure the phase transitions in the following ferroelectric compounds: 95% PbZ4₀.₈Ti₀.₂ - 5% BiFeO₃ [and] 95% PbZ4₀.₇Ti₀.₃ - 5% BiFeO₃ and in the antiferroelectric compound: 95% PbZrO₃ - 5% BiFeO₃. The parameters obtained were the area under the resonance peak, the isomer shift, and the electric quadrupole splitting, all as a function of temperature. The ionicity, electric field gradient, and Debye temperature were determined for room temperature. The data are discussed in terms of the lattice vibration model of ferroelectrics and antiferroelectrics, and the structural phase transitions as recently defined for these compounds. The …
Mhd Waves In The Inner Magnetosheath, Jiann Tsorng Horng
Mhd Waves In The Inner Magnetosheath, Jiann Tsorng Horng
Doctoral Dissertations
No abstract provided.
The Energy Spectrum And Flux Of Fast Neutrons In The Atmosphere, Richard Norbert St. Onge
The Energy Spectrum And Flux Of Fast Neutrons In The Atmosphere, Richard Norbert St. Onge
Doctoral Dissertations
No abstract provided.
High Temperature Optical Pumping And The Hyperfine Structure Of Nitrogen, Roger Edward Weiss
High Temperature Optical Pumping And The Hyperfine Structure Of Nitrogen, Roger Edward Weiss
Doctoral Dissertations
No abstract provided.
Investigation Of Auroral Phenomena By Sounding Rocket, Wentworth Edwards Potter
Investigation Of Auroral Phenomena By Sounding Rocket, Wentworth Edwards Potter
Doctoral Dissertations
No abstract provided.
Response Of The Rat Ovary To Continuous Light: Effects Of Light Frequency, Intensity And Duration Of Exposure, Helen Haynes Lambert
Response Of The Rat Ovary To Continuous Light: Effects Of Light Frequency, Intensity And Duration Of Exposure, Helen Haynes Lambert
Doctoral Dissertations
No abstract provided.
Hyperfine Splittings And Pressure Shifts Of Lithium-6 And Lithium-7, John Jay Wright
Hyperfine Splittings And Pressure Shifts Of Lithium-6 And Lithium-7, John Jay Wright
Doctoral Dissertations
No abstract provided.
Investigation Of The Effect Of Molecular Geometry On The Electronic Structures Of Styrene And Indene, James Denis Quirk
Investigation Of The Effect Of Molecular Geometry On The Electronic Structures Of Styrene And Indene, James Denis Quirk
Doctoral Dissertations
No abstract provided.
Studies In Atomic Fluorescence Flame Spectroscopy, Donald Romeo Demers
Studies In Atomic Fluorescence Flame Spectroscopy, Donald Romeo Demers
Doctoral Dissertations
No abstract provided.
A Search For High Energy Solar Neutrons, David John Forrest
A Search For High Energy Solar Neutrons, David John Forrest
Doctoral Dissertations
No abstract provided.
Hot Atom Chemistry Of Phosphorus-32 In Alkali Chlorides And Sodium Silicates, Meral Tayan Ercan
Hot Atom Chemistry Of Phosphorus-32 In Alkali Chlorides And Sodium Silicates, Meral Tayan Ercan
Doctoral Dissertations
No abstract provided.
Statistical Inferences For The Generalized Gamma Distribution, Harold Walter Hager
Statistical Inferences For The Generalized Gamma Distribution, Harold Walter Hager
Doctoral Dissertations
"Procedures for handling statistical problems with nuisance parameters are considered with special reference to problems in the three parameter generalized gamma distribution. Maximum likelihood estimation of the parameters of this density has been investigated. Properties of these estimates are established which make it possible to make inferences about the parameters. Discrimination between various models for life testing problems is discussed and the robustness of the Weibull model is advanced. The question of the existence of the maximum likelihood estimates of the parameters for all samples is raised. Empiric evidence is presented indicating that they may not exist for all small …
An Optimization Approach To Well Spacing For Gas Storage Reservoirs, Jagannath Rao Ghole
An Optimization Approach To Well Spacing For Gas Storage Reservoirs, Jagannath Rao Ghole
Doctoral Dissertations
"A finite approximation to the conventional diffusivity equation describing compressible fluid flow through porous media has been developed with a view to apply it to the problems of optimum well spacing. An equilateral grid system has been employed to enable uniform well spacing for any number of wells. A numerical model has been developed on an IBM 360 - Model 50 computer, which simulates the pressure and saturation transience in the reservoir due to production impulses. This model has been used to maximize with respect to number of wells, the minimum well bore pressure reached throughout the specified withdrawal schedule. …
Mass And Heat Transfer Through Nonwettable Porous Membranes, Chung-Liang Yeh
Mass And Heat Transfer Through Nonwettable Porous Membranes, Chung-Liang Yeh
Doctoral Dissertations
"Evaporation of water through nonwettable porous membranes has been studied under various pressures with various membrane thicknesses. The results of previous investigations at 1 atmosphere have been correlated into one equation for mass transfer resistance which has also been found to fit approximately new data obtained of 1.5, 2, and 3 atmospheres in this investigation. In the new data fluxes varied from 0.064 to 0.691 lb./ft.²/hr. through glass fiber-Teflon membrane from 0.02 to 0.08 inch in thickness. Temperatures ranged for 80 to 260°F. A more theoretical equation has been developed to explain variations from the equations based on 1 atmosphere …
A Five Parameter Study Of Spherical Transient Waves In A Generalized Voigt Model, Liang-Juan Tsay
A Five Parameter Study Of Spherical Transient Waves In A Generalized Voigt Model, Liang-Juan Tsay
Doctoral Dissertations
"Transient spherical waves in a generalized Voigt model were investigated in this study. Both Laplace and fourier transform solutions of the spherical wave equation for a generalized Voigt model were obtained by means of the correspondence principle. Laplace transform solutions were inverted numerically into the domain for the study of the characteristics of the wave forms, and Fourier transform solutions were utilized for the analysis of frequency dependency attenuation in the models. Generalized Voigt models A and B in which a dashpot is connected in series with spring and dashpot components were unable to represent a solid which would simulate …
Diffusion Of Iron And Cobalt In Nickel Single Crystals, Charles Frederick Heuer
Diffusion Of Iron And Cobalt In Nickel Single Crystals, Charles Frederick Heuer
Doctoral Dissertations
"Diffusion coefficients of iron-59 in nickel have been determined in the temperature range 815°C to 1200°C. The temperature dependence can be represented by an Arrhenius type relationship,...The effect of the isotopic mass on the diffusion coefficient of cobalt in nickel has also been investigated. The isotope effect parameter, E, was found to vary from .26 to .84 over the temperature range 970.5°C to 1200°C. Both results are consistent with the single vacancy mechanism of diffusion. No evidence of divacancy contributions to the mass transport has been found"--Abstract, Page i.
Radiative Lifetime Of The B¹Σ⁺ And B³Σ⁺ States Of Carbon Monoxide, John Robert Rogers
Radiative Lifetime Of The B¹Σ⁺ And B³Σ⁺ States Of Carbon Monoxide, John Robert Rogers
Doctoral Dissertations
"The radiative lifetimes of the B¹Σ⁺ and b³Σ⁺ excited states of carbon monoxide were measured at six different pressures: 10, 25, 50, 75, 100, and 125 microns of Hg. The lifetimes were obtained by observation of the radiative decay of the (0,0), (0,1), (0,2), and (1,1) bands of the Angstrom system and the radiative decay of the (0,1), (0,2), (0,3), and (0,4) bands of the Third Positive system. No pressure dependence of the lifetimes was observed for either system. The average lifetime of the v' = 0 vibrational level of the B¹Σ⁺ state was found to be 24.4 x 10⁻⁹ …
A Study Of The Energy Loss Spectra Induced By Impact Of 23-125 Kev Protons On Helium Atoms, Franklin Dean Schowengerdt
A Study Of The Energy Loss Spectra Induced By Impact Of 23-125 Kev Protons On Helium Atoms, Franklin Dean Schowengerdt
Doctoral Dissertations
"Results of a study of the inelastic energy loss spectra induced by the impact of protons on gaseous helium at energies of 25 to 125 keV are reported. The spectra were obtained by sending an accelerated beam of protons through a chamber containing the helium target gas, mass-analyzing the forward-scattered beam, then decelerating the beam to a low, well-defined energy for energy analysis and detection. The accelerating potential was varied to produce the spectra. An energy resolution of 2 eV was obtained. Apparent differential cross sections and absolute total cross sections were obtained from the spectra. Total cross sections for …
A Crystallization Study Of A Tetrasilicic Fluormica Glass, William H. Daniels
A Crystallization Study Of A Tetrasilicic Fluormica Glass, William H. Daniels
Doctoral Dissertations
"The transformation of a synthetic mica composition K₂Mg₅Si₈O₂₀F₄ from amorphous to crystalline structure was studied isothermally at selected temperatures from 560°C to 1150°C. thermal changes associated with the transformation were followed by differential thermal analysis techniques. Structural changes promoted by the isothermal treatments were observed by density measurements, Debye-Scherrer X-ray diffraction techniques, electron replication microscopy, and electron scanning microscopy. Isothermal treatment at 450°C for 9 hours produces structural ordering in quenched K₂Mg₅Si₈O₂₀F₄ glass. Fluorine exerts a significant influence on the transformation temperature; decreasing amounts of fluorine producing increasing transformation temperatures. The crystallizing phase rapidly attains a limiting particle size and …
Grain Boundary Self-Diffusion In Sodium Chloride, Kenneth Ray Riggs
Grain Boundary Self-Diffusion In Sodium Chloride, Kenneth Ray Riggs
Doctoral Dissertations
"The diffusion of ²²sodium and ³⁶chlorine along tilt and twist grain boundaries in pure and calcium chloride doped sodium chloride bicrystals was investigated. No enhanced diffusion of ²²sodium along the grain boundaries was observed. Between 400°C and 500°C the chlorine grain boundary diffusion parameter, D'Δ, is described by D'Δ = (D'Δ)₀exp (-Qb/kT), where (D'Δ)₀ is approximately 10⁻⁷ cm³/sec and Qb is 1.15 ± .30 eV. The grain boundary angle, the grain boundary character (tilt or twist), and the calcium chloride concentration appear to have no pronounced effect upon the observed chlorine grain boundary diffusion. The ionic movement …
Low-Lying Levels In Some Spherical And Rotational Nuclides By Coulomb Excitation And Radiative Capture Of Thermal Neutrons, Donald Allan Mcclure
Low-Lying Levels In Some Spherical And Rotational Nuclides By Coulomb Excitation And Radiative Capture Of Thermal Neutrons, Donald Allan Mcclure
Doctoral Dissertations
"The work presented in this dissertation was performed in order to obtain additional information on the level schemes and decay properties of several nuclei in an attempt to explain the observations in terms of an applicable nuclear model. Various nuclear models are discussed in Section II. A general review from the classical point of view of the Coulomb excitation reaction is discussed in Section III and the thermal-neutron-capture reaction is outlined in Section IV. The experimental equipment and procedure is discussed in Section V in which the ramper method of energy determination is outlined. This method allows the measurement of …
Microwave Propagation Through Isotropic Inhomogeneous Photoconductive Media, Thomas Van Doren
Microwave Propagation Through Isotropic Inhomogeneous Photoconductive Media, Thomas Van Doren
Doctoral Dissertations
"The electromagnetic field equations for microwave propagation through a rectangular waveguide filled with a lossy, isotropic, linear, inhomogeneous material are derived in matrix form and solved numerically by computer. The theoretical effects of photo-induced conductivity and dielectric constant variations on microwave attenuation, phase shift, and voltage standing wave ratio are plotted for typical examples in the X-band frequency range. The theoretical calculations indicate that a two order-of-magnitude change in the conductivity can produce a 25 db change in the attenuation or a 100 degree change in the angle of the reflection coefficient. The theoretical predictions are verified qualitatively by experiments …
Spherical Antenna Array, Narong Yoothanom
Spherical Antenna Array, Narong Yoothanom
Doctoral Dissertations
"The far field radiation pattern of an isotropic spherical antenna array with two types of element distributions, a latitude-longitude distribution and an approximately equally-spaced distribution, has been analyzed using Poisson's Sum Formula. Beamwidth expressions of both element distributions are found in various planes. All numerical results are given only for the case of 21 rings"--Abstract, page ii.
The Iron-Holmium Binary System And Related Magnetic Properties, Gerald J. Roe
The Iron-Holmium Binary System And Related Magnetic Properties, Gerald J. Roe
Doctoral Dissertations
"The iron-holmium phase diagram was investigated to determine the alloying behavior of these two metals and to determine the magnetic properties of some of the iron-holmium alloys which formed intermediate phases. The iron-holmium binary system was determined by three experimental techniques, differential thermal analysis (DTA), x-ray diffraction, and metallography. A phase diagram with three eutectic points and four intermediate phases was constructed from the experimental data. The two phases, Ho₆Fe₂₃ and Ho₂Fe₁₇, melted congruently at 1322⁰C and 1343⁰C respectively. HoFe₂ and HoFe₃ melted incongruently at 1288⁰C and 1293⁰C respectively. Neutron diffraction investigations were made on the intermediate phases Ho₆Fe₂₃ and …
Statistical Inferences For Location And Scale Parameter Distributions, Robert Henry Dumonceaux
Statistical Inferences For Location And Scale Parameter Distributions, Robert Henry Dumonceaux
Doctoral Dissertations
"The problem of discriminating between two location and scale parameter distributions is investigated. A general test based on a ratio of likelihoods is presented. A test based on a Pearson Goodness of Fit statistic is also considered. Tables are given for discriminating between the normal and exponential, the normal and double exponential, the normal and extreme value, and also between the normal and logistic. For location and scale parameter distributions, two-sided tolerance limits are shown to always be obtainable by Monte Carlo simulation. A method for obtaining confidence intervals on the reliability at a fixed time t is also given. …
A Theoretical Study On The Interpretation Of Resistivity Sounding Data Measured By The Wenner Electrode System, Siew Hung Chan
A Theoretical Study On The Interpretation Of Resistivity Sounding Data Measured By The Wenner Electrode System, Siew Hung Chan
Doctoral Dissertations
"This thesis deals with a theoretical study on the interpretation of resistivity sounding data measured by the Wenner electrode system. The objectives of this investigation are twofold: (i) to derive from the apparent resistivity data some suitable functions from which the resistivity and thickness of each member of the sequence of layers composing the earth may be determined, and (ii) to devise suitable methods for analyzing the resulting functions. In this investigation it is shown that the solution of the boundary value problem associated with an n-layered earth model leads to an integral equation for the Wenner electrode system. This …
A.C. Hall Effect Measurements On Very High Resistivity Materials Exhibiting Electrode Polarization, James Dale Boyd
A.C. Hall Effect Measurements On Very High Resistivity Materials Exhibiting Electrode Polarization, James Dale Boyd
Doctoral Dissertations
"A variable frequency, a.c. Hall effect measurement technique has been designed for mobility studies in very high resistivity (>10⁹ ohm·cm) materials exhibiting electrode space charge polarization effects. It incorporates a neutralized input capacitance preamplifier detector which reduces the total input shunting capacitance, including the sample interelectrode capacitances, to a very low, definable value (<0.1 pf) and thereby provides very high and well defined a.c. detector input impedances (4 x 10⁹ and 7 x 10⁹ ohms at 600 and 200 Hz, respectively). Lumped parameter equivalent circuits have been defined to approximate the electrical behavior of sample materials in the measurement configuration. These equivalent circuits, together with independent measurements of the detector input and sample impedances, allow one to correct the detected Hall voltage and obtain the true value from which mobility data may be derived. The validity of these circuits has been established by independent a.c. and d.c. measurements on photoconductive CdS (dark resistivity >10¹⁰ ohm·cm) which exhibited maximum differences of less than 4%. The existing literature has been critically reviewed and the measurement criteria established by this study have been applied to resolve differences in reported data and to suggest improvements in the resolution of previously employed experimental …