Open Access. Powered by Scholars. Published by Universities.®
- Institution
-
- Old Dominion University (254)
- University of Nebraska - Lincoln (192)
- Air Force Institute of Technology (31)
- University of South Carolina (21)
- Technological University Dublin (17)
-
- University of Dayton (17)
- Western Kentucky University (11)
- California Polytechnic State University, San Luis Obispo (9)
- University of New Mexico (8)
- City University of New York (CUNY) (7)
- University of Mississippi (6)
- Xavier University (6)
- Embry-Riddle Aeronautical University (5)
- The University of Maine (5)
- Brigham Young University (4)
- Florida International University (3)
- Minnesota State University, Mankato (3)
- Purdue University (3)
- University of Massachusetts Amherst (3)
- University of Nevada, Las Vegas (3)
- Utah State University (3)
- Bridgewater College (2)
- Coastal Carolina University (2)
- Hope College (2)
- Indian Statistical Institute (2)
- Marshall University (2)
- San Jose State University (2)
- Augustana College (1)
- Bridgewater State University (1)
- Central Washington University (1)
- Keyword
-
- Cavity (61)
- Electron (33)
- SRF (33)
- Niobium (23)
- HOM (19)
-
- Simulation (18)
- Luminosity (15)
- Experiment (14)
- Gun (14)
- Particle accelerators (13)
- Damping (12)
- Laser (12)
- Cathode (11)
- Superconductivity (11)
- Cavities (10)
- Dipole (10)
- Superconducting cavities (10)
- Collider (9)
- Emittance (9)
- Physics (9)
- Geometry (8)
- Magnetic fields (8)
- Radio-frequency (8)
- Solenoid (8)
- Superconducting RF (8)
- Thin films (8)
- Accelerators (7)
- Cryomodule (7)
- Impedance (7)
- Radiation (7)
- Publication Year
- Publication
-
- Physics Faculty Publications (216)
- Nebraska Center for Materials and Nanoscience: Faculty Publications (58)
- Faculty Publications (56)
- Electrical & Computer Engineering Faculty Publications (37)
- Xiaoshan Xu Papers (32)
-
- Peter Dowben Publications (30)
- Xia Hong Publications (21)
- Shireen Adenwalla Papers (12)
- Kirill Belashchenko Publications (11)
- Alexei Gruverman Publications (10)
- Articles (9)
- Masters Theses & Specialist Projects (9)
- STAR Program Research Presentations (9)
- Branch Mathematics and Statistics Faculty and Staff Publications (8)
- Faculty Scholarship (6)
- Gulf Research Program Data Sets (6)
- Mechanical & Aerospace Engineering Faculty Publications (6)
- Publications and Research (6)
- Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research (5)
- Honors College (5)
- Journal Articles (5)
- Publications (5)
- Conference Papers (4)
- Directivity (4)
- Mathematics & Statistics Faculty Publications (4)
- Mathematics Faculty Publications (4)
- Aviation Department Publications (3)
- Bioelectrics Publications (3)
- Doctoral (3)
- Engineering Technology Faculty Publications (2)
- File Type
Articles 631 - 656 of 656
Full-Text Articles in Physics
A Novel Laboratory Course On Advanced Chemical Engineering Experiments, Jochen A. Lauterbach, S. White, X. Lui, G. M. Bodner, W. N. Delgass
A Novel Laboratory Course On Advanced Chemical Engineering Experiments, Jochen A. Lauterbach, S. White, X. Lui, G. M. Bodner, W. N. Delgass
Faculty Publications
The chemical engineering curriculum in the United States has trained generations of technical experts who have successfully optimized chemical processes and products once they entered the chemical industry. The U.S. chemical industry, however, has entered a critical stage in which it must be able to create new and differentiated value through technical innovations that arc essential for long-term survival. This innovation process will require new skills that go far beyond the traditional expertise for the optimization of tasks possessed by young chemical engineers. The innovators must be able to identify new opportunities, explore the boundaries of technology, evaluate critical issues, …
An Electroabsorption Study Of Porous Silicon, Melanie Fewings
An Electroabsorption Study Of Porous Silicon, Melanie Fewings
WWU Honors College Senior Projects
Bulk silicon is an indirect band gap material. When carriers are injected into bulk silicon, electron-hole recombination takes place thermally via phonon exchange, and not by emission of photons. Porous silicon, on the other hand, is a fairly efficient emitter of light in the visible region. Much research is currently under way to find out what makes porous silicon able to emit light. One main theory suggests that the energy bands of bulk silicon may be "squeezed" by being quantum confined, and porous silicon is just an array of quantum silicon wires. Another possibility is that defects in the huge …
Comparison Of Time-Domain Reflectometry Performance Factors For Several Dielectric Geometries: Theory And Experiments, S. V. Maheshwarla, R. Venkatasubramanian, Robert F. Boehm
Comparison Of Time-Domain Reflectometry Performance Factors For Several Dielectric Geometries: Theory And Experiments, S. V. Maheshwarla, R. Venkatasubramanian, Robert F. Boehm
Electrical & Computer Engineering Faculty Research
We propose three nontraditional dielectric geometries and present an experimental and theoretical analysis and comparison of time domain reflectometry (TDR) performances for them. The traditional geometry (the probes inserted in material of essentially infinite extent) is compared to three nontraditional geometries where the probes are affixed outside of a core sample, inside of a bore, or flat on the surface of a semi-infinite solid. Our derivation relates the velocity of electromagnetic wave propagation to the complex permittivities and permeabilities of the media and the geometry for the three nontraditional configurations. Experimental results for air, styrofoam, dry sand, wet sand of …
Characterization Of Piezoceramic Crosses With Large Range Scanning Capability And Applications For Low Temperature Scanning Tunneling Microscopy, J. A. Helfrich, Shireen Adenwalla, J. B. Ketterson, G. A. Zhitomirsky
Characterization Of Piezoceramic Crosses With Large Range Scanning Capability And Applications For Low Temperature Scanning Tunneling Microscopy, J. A. Helfrich, Shireen Adenwalla, J. B. Ketterson, G. A. Zhitomirsky
Shireen Adenwalla Papers
We have developed a large amplitude piezoceramic scanner which should have numerous applications. Scanning tunneling microscopy (STM) and other scanning probe microscopies predominantly use piezoceramics for the scanning elements. Similarly adaptive optics, high resolution lithography, and micromanipulators are other examples of research which regularly utilize piezoceramic scanners. We present a new geometry for a piezoceramic scanner which allows for both high resolution (~nanometers) and large amplitude (~400 µm) displacements. The cross-shaped geometry makes it possible to produce extremely long pieces with very high tolerances. We have shown its effectiveness by using it as the major component of a low temperature …
Supralinear Photoconductivity Of Copper Doped Semi-Insulating Gallium Arsenide, K. H. Schoenbach, R. P. Joshi, F. Peterkin, R. L. Druce
Supralinear Photoconductivity Of Copper Doped Semi-Insulating Gallium Arsenide, K. H. Schoenbach, R. P. Joshi, F. Peterkin, R. L. Druce
Bioelectrics Publications
We report on the intensity dependent supralinear photoconductivity in GaAs:Si:Cu material. The results of our measurements show that the effective carrier lifetime can change over two orders of magnitude with variations in the intensity of the optical excitation. A threshold intensity level has been observed and can be related to the occupancy of the deep copper level. Numerical simulations have also been carried out to analyze the trapping dynamics. The intensity dependent lifetimes obtained from the simulations match the experimental data very well. Finally, based on the nonlinear intensity dependence of the effective lifetimes, a possible low‐energy phototransistor application for …
Low‐Cost Technique For Preparing N‐Sb2S3/P‐Si Heterojunction Solar Cells, O. Savadogo, K. C. Mandal
Low‐Cost Technique For Preparing N‐Sb2S3/P‐Si Heterojunction Solar Cells, O. Savadogo, K. C. Mandal
Faculty Publications
No abstract provided.
Electrostatic Positioning Of Droplets In Turbulent Flows (Lstm 375/Te/93), Nihad E. Daidzic, Adrian Melling
Electrostatic Positioning Of Droplets In Turbulent Flows (Lstm 375/Te/93), Nihad E. Daidzic, Adrian Melling
Aviation Department Publications
Report LSTM 375/TE/93, Lehrstuhl fuer Stroemungsmechanik Universitaet Erlangen-Nuernberg Cauerstr. 4, 8520 Erlangen Germany.
A Magnetic Suspension System With A Large Angular Range, Colin P. Britcher, Mehran Ghofrani
A Magnetic Suspension System With A Large Angular Range, Colin P. Britcher, Mehran Ghofrani
Mechanical & Aerospace Engineering Faculty Publications
In order to explore and develop technology required for the magnetic suspension of objects over large ranges of orientation, a small-scale laboratory system, the large-angle magnetic suspension test fixture (LAMSTF) has been constructed at NASA Langley Research Center. This apparatus falls into the category of large-gap, actively stabilized magnetic levitation systems. The hardware comprises five conventional electromagnets in a circular arrangement, each driven from a separate bipolar power amplifier. Electromagnet currents are commanded by a digital control system, implemented on a microcomputer, which in turn derives the position and attitude of the suspended element from an infrared optical system. The …
Hysteresis And Anchoring Energy In Ferroelectric Liquid Crystals, Yuri Panarin
Hysteresis And Anchoring Energy In Ferroelectric Liquid Crystals, Yuri Panarin
Articles
The frequency dispersion of the coercive force of Ferroelectric Liquid Crystals (FLC) cells has been detected and examined in the range of infralow (lower than 0.1 Hz) frequencies. To clarify the low-frequency dispersion, the model has been suggested, based on the arrangement of free charges and well describing the experimental curves. The method for determination of the energy of FLC anchoring at the surface, developed on the basis of the static hysteresis loop, has been proposed. The dependence of bistability and the anchoring energy upon the orientant layer thickness has experimentally been investigated.
Some Stability Problems In Droplet Formation And Breakup (Report Lstm 351/T/92)., Nihad E. Daidzic
Some Stability Problems In Droplet Formation And Breakup (Report Lstm 351/T/92)., Nihad E. Daidzic
Aviation Department Publications
In this study the instability of droplets and cylindrical jets is investigated. The understanding of these processes has both academic and practical value. Instability of cylindrical jets is theoretically investigated for infinitesimal and finite, but small initial amplitudes (linear and nonlinear stability). For droplets, only linear theory is presented. It is assumed that the capillary force play a dominant role. It is determined that the viscosity exerts a damping effect. In the first section we give an introduction, after which the linear stability theory of cylindrical liquid jets is presented. In the third section the nonlinear jet stability theory is …
Detection, Location, And Quantification Of Structural Damage By Neural-Netprocessed Moire Profilometry, Barry G. Grossman, Frank S. Gonzalez, Joel H. Blatt, Jeffery A. Hooker
Detection, Location, And Quantification Of Structural Damage By Neural-Netprocessed Moire Profilometry, Barry G. Grossman, Frank S. Gonzalez, Joel H. Blatt, Jeffery A. Hooker
Electrical Engineering and Computer Science Faculty Publications
The development of efficient high speed techniques to recognize, locate, and quantify damage is vitally important for successful automated inspection systems such as ones used for the inspection of undersea pipelines. Two critical problems must be solved to achieve these goals: the reduction of nonuseful information present in the video image and automatic recognition and quantification of extent and location of damage. Artificial neural network processed moire profilometry appears to be a promising technique to accomplish this. Real time video moire techniques have been developed which clearly distinguish damaged and undamaged areas on structures, thus reducing the amount of extraneous …
Effect Of Magnetic And Density Fluctuations On The Propagation Of Lower Hybrid Waves In Tokamaks, George Vahala, Linda L. Vahala, Paul T. Bonoli
Effect Of Magnetic And Density Fluctuations On The Propagation Of Lower Hybrid Waves In Tokamaks, George Vahala, Linda L. Vahala, Paul T. Bonoli
Electrical & Computer Engineering Faculty Publications
Lower hybrid waves have been used extensively for plasma heating, current drive, and ramp-up as well as sawteeth stabilization, The wave kinetic equation for lower hybrid wave propagation is extended to include the effects of both magnetic and density fluctuations. This integral equation is then solved by Monte Carlo procedures for a toroidal plasma. It is shown that even for magnetic/density fluctuation levels on the order of 10-4, there are significant magnetic fluctuation effects on the wave power deposition into the plasma. This effect is quite pronounced if the magnetic fluctuation spectrum is peaked within the plasma. For …
Measuring R And D Productivity, Richard A. Pappas, Donald S. Remer
Measuring R And D Productivity, Richard A. Pappas, Donald S. Remer
All HMC Faculty Publications and Research
Measuring the productivity of an R&D organization is extremely tricky. Productivity is usually defined as a ratio of an output, like number of cars produced on an assembly line, to an input, like the wages paid the workers. While R&D may have a measurable input, the output is often intangible and difficult to quantify. This is further complicated because the return from an R&D department may not be realized for one or two decades,which means the time lag is much higher than in factory measurements. Furthermore, many researchers believe that this kind of measurement may be counterproductive,since the mere act …
Systematic Estimate Of Binding Energies Of Weakly Bound Diatomic Molecules, Linda L. Vahala, Mark D. Havey
Systematic Estimate Of Binding Energies Of Weakly Bound Diatomic Molecules, Linda L. Vahala, Mark D. Havey
Electrical & Computer Engineering Faculty Publications
There is often insufficient spectroscopic data for a full RKR inversion to yield a potential for weakly bound diatomic molecules. In these cases, parametrized functions such as the Morse or Thakkar potentials may be used to obtain estimates of the binding energy. The Thakkar potential is more flexible, and has been used successfully on some weakly bound systems. In the more usual case, the Thakkar parameter p, which determines long range behavior R-p, is chosen by p=-a1-1, where a1 is the first Dunham coefficient; p is usually noninteger. The authors present …
Picosecond Laser Pulse Irradiation Of Crystalline Silicon, K. L. Merkle, H. Baumgart, R.H. Uebbing, F. Phillipp
Picosecond Laser Pulse Irradiation Of Crystalline Silicon, K. L. Merkle, H. Baumgart, R.H. Uebbing, F. Phillipp
Electrical & Computer Engineering Faculty Publications
Morphology changes introduced by picosecond laser pulses at λ = 532 nm and 355 nm in (111) and (100) silicon samples are studied by means of optical and high-voltage electron microscopy. Depending on energy fluence, orientation and wavelength, amorphous or highly defective regions may be created. From an analysis of damage thresholds and damage depth distributions it is concluded that melting and energy confinement precedes the formation of the structural changes.
An Apparatus For Measuring The Thermal Conductivity Of Cast Insulation Materials, Christine A. Wilkins, Robert L. Ash
An Apparatus For Measuring The Thermal Conductivity Of Cast Insulation Materials, Christine A. Wilkins, Robert L. Ash
Mechanical & Aerospace Engineering Faculty Publications
A steady-state apparatus has been developed for measuring the thermal conductivity of cast materials. The design has employed a novel thermal symmetry arrangement which can permit total electrical isolation of the test material from its surroundings. © 1980 American Institute of Physics
Calculated Temperature Of Grid Lateral Wires In Microwave Power Triodes, Jewell Tucker
Calculated Temperature Of Grid Lateral Wires In Microwave Power Triodes, Jewell Tucker
Masters Theses & Specialist Projects
In microwave power triodes the grid drive power causes grid lateral wire heating. This development calculates the temperature of the wire as a function of the drive power, physical dimensions and characteristics of the wire material, for the following boundary conditions:
I. Constant grid drive, grid lateral wire of infinite length not connected to a heat sink.
II. Same as I except the wire is of finite length brazed to a grid frame.
III. The grid excitation in the form of pulses, and the grid lateral wire of finite length brazed to a grid frame.
the equations were verified experimentally …
Science Foundations: A Science Program For The Non-Science Student. Technical Report No. 4., James Shymansky
Science Foundations: A Science Program For The Non-Science Student. Technical Report No. 4., James Shymansky
Educator Preparation & Leadership Faculty Works
No abstract provided.
Measurement Of Currents In Lake Mead With The Deep Water Isotopic Current Analyzer (Dwica), J. J. Sartoris, D. A. Hoffman, Bureau Of Reclamation
Measurement Of Currents In Lake Mead With The Deep Water Isotopic Current Analyzer (Dwica), J. J. Sartoris, D. A. Hoffman, Bureau Of Reclamation
Publications (WR)
In Nov 1967, a Deep Water Isotopic Current Analyzer (DWICA) was used to study current patterns in the Boulder Basin of Lake Mead to determine if low-quality water from Las Vegas Bay might enter the Southern Nevada Water Project intake on Saddle Island. Secondary objectives were to study the general current patterns in Boulder Basin and the effect of power discharges at Hoover Dam on these currents. Results of current measurements at 3 stations in Boulder Basin are given. Observations indicate a definite possibility that low-quality water from Las Vegas Bay might enter the water intake on Saddle Island. Current …
Determination Of (N, 2n) Reaction Cross-Sections For 71ga, 106cd & 138ba Using 14 Mev Neutrons, Thomas Helm
Determination Of (N, 2n) Reaction Cross-Sections For 71ga, 106cd & 138ba Using 14 Mev Neutrons, Thomas Helm
Masters Theses & Specialist Projects
The increasing trend towards the use of activation analysis as an analytic means of identifying elements and determining their relative abundance demands more accurate values of reaction cross-sections. Accurate values of cross-sections are also important in the investigation of possible shell effects in reaction mechanisms. Many activation cross-sections for reactions produced by 14 MeV neutrons have been measured because of the relative ease with which this energy of neutrons can be produced. Low voltage accelerators are capable of producing 14. MeV neutrons by the 3H( d,n)4He reaction. Although many people(1-5) have measured the (n,2n) reaction cross-sections …
A Nonsecond Time-Of-Flight Spectometer, David Moorman
A Nonsecond Time-Of-Flight Spectometer, David Moorman
Masters Theses & Specialist Projects
The purpose of this thesis was to construct a time-of-flight spectrometer using plastic scintillators coupled to photomultiplier tubes as the primary detectors. A time-of-flight spectrometer with at least 2.0 nanoseconds of time resolution was desired.
Electrical Conductivity & Seebeck Effect In Activated Molybdenum Oxide Hydrogen Detectors, John Hooker
Electrical Conductivity & Seebeck Effect In Activated Molybdenum Oxide Hydrogen Detectors, John Hooker
Masters Theses & Specialist Projects
This thesis describes the results and analysis of Seebeck coefficient and electrical conductivity measurements on "activated", molybdenum-oxide, thin film hydrogensensing elements. The work was undertaken in an effort to produce data that would be useful in obtaining an understanding of the electronic processes which cause large electrical conductivity changes in molybdenum-oxide upon exposure to small concentrations of hydrogen in air. The results are analyzed using a simple band model of a semiconductor. This model is shown to give reasonable results at high temperatures; however, a departure from the usual .! model is required in order to explain the results at …
Crossed Field Trochoidal Trajectory Devices For Investigating The Reflection Of Slow Electrons From Metallic Surfaces, Stan Lemaster
Crossed Field Trochoidal Trajectory Devices For Investigating The Reflection Of Slow Electrons From Metallic Surfaces, Stan Lemaster
Masters Theses & Specialist Projects
The objective of this study was to build preliminary devices . which could be used to measure electron reflection coefficient values using crossed electric and magnetic fields. The technique for using crossed fields to measure reflection coefficients was developed at Air Force Cambridge Research Laboratories. The reflection coefficient is the ratio of the number of electrons in a reflected beam to the number of electrons in an incident beam striking a surface.
The work described herein was a part of a project authored by AFCRL under contract AF19 (628)-5940; Project 8605 (with Western Kentucky University being the contractor) which was …
Solid State Electrolysis Of Yttria Stablized Zirconia, John Newman
Solid State Electrolysis Of Yttria Stablized Zirconia, John Newman
Masters Theses & Specialist Projects
Zirconium dioxide, or zirconia, is seemingly an ideal refractory oxide, having a high melting point (2680°C), low thermal expansion and also a considerable resistance to most forms of chemical attack. Early researchers soon found that zirconia, in the pure form, was actually of very limited use as a refractory because of sudden and disruptive volume changes accompanying a change in crystal structure which occurs at a temperature of about 1100 o C. It was discovered that this crystal structure change could be suppressed by the addition of one of a number of alkaline earth or rare earth oxides. These additive …
Environmental Effects On The Resistivity Of Palladium-Silver Alloy Films In High Vacuum, Frank Snyder
Environmental Effects On The Resistivity Of Palladium-Silver Alloy Films In High Vacuum, Frank Snyder
Masters Theses & Specialist Projects
The reported usage of the palladium-silver alloy films as resistors in the electronics industry has been in encapsulated form. By mounting the resistor inside vacuum electron devices, there is the possibility of eliminating the encapsulation. A literature search has revealed no reported efforts of experiments with unencapsulated resistors and certainly no reports of the palladium-silver alloy resistor in vacuum tubes or other high vacuum environments. Therefore, the research reported in this thesis will concentrate on the environmental effects on resistivity of palladium-silver alloy films in high vacuum.
An Experimental Study Of The Cathode Fall In Helium And Argon With Wire Cathodes, L. G. Raub
An Experimental Study Of The Cathode Fall In Helium And Argon With Wire Cathodes, L. G. Raub
Papers from the University Studies series (University of Nebraska)
It was recognized rather early in the study of the phenomena of discharge of electricity through gases that the ordinary laws of conduction as found in solid and liquid conductors are not applicable to gases. It was shown by Zeleny and independently by Child that Ohm's law by no means represents the distribution of potential between electrodes in an ionized gas, but that the potential gradient is large in the vicinity of the electrodes, and not uniform throughout the space between them. When the pressure of the gas surrounding the electrodes is reduced to one or two millimeters and a …