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Analysis of valence-electron structures of Y/sub 3/Al/sub 5/O/sub 12/(YAG) and Al/sub 2/O/sub 3/, Cr/sub 2/O/sub 2/ (Ruby), a study of certain properties of these laser materials related to their valence-electron structures

Description: A direct method of determination of the valence-electron structure from its crystal structure has been presented by the writer at XIIth International Congress of Crystallography, at Ottawa, 1981. Here the method is applied to determine the valence-electron structures of Y/sub 3/Al/sub 5/O/sub 12/ (YAG) and Al/sub 2/O/sub 3/, Cr/sub 2/O/sub 3/ (ruby) to see how certain properties of these laser materials are related to their valence-electron structures. The first point observed is the very stron… more
Date: January 1, 1982
Creator: Yu, S. H. & Yu, L. H.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Modeling of low-level-waste disposal for environmental impact analysis

Description: A computer model was developed to analyze environmental impacts resulting from disposal of both radioactive and chemical wastes. The model simulates a waste-disposal system and includes infiltration through disposal cell caps, source leach rates, and solute transport in geologic media. The solute transport model used is a modified version of an analytical code originally developed at Oak Ridge National Laboratory. The solute transport code was modified based on the Group-Transfer Concentration … more
Date: January 1, 1987
Creator: Yu, C.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Inverse problem in radionuclide transport

Description: The disposal of radioactive waste must comply with the performance objectives set forth in 10 CFR 61 for low-level waste (LLW) and 10 CFR 60 for high-level waste (HLW). To determine probable compliance, the proposed disposal system can be modeled to predict its performance. One of the difficulties encountered in such a study is modeling the migration of radionuclides through a complex geologic medium for the long term. Although many radionuclide transport models exist in the literature, the acc… more
Date: January 1, 1988
Creator: Yu, C.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Groundwater pathway sensitivity analysis and hydrogeologic parameters identification for waste disposal in porous media

Description: The migration of radionuclides in a geologic medium is controlled by the hydrogeologic parameters of the medium such as dispersion coefficient, pore water velocity, retardation factor, degradation rate, mass transfer coefficient, water content, and fraction of dead-end pores. These hydrogeologic parameters are often used to predict the migration of buried wastes in nuclide transport models. One of the most important factors determining the accuracy of predicting waste migration is the accuracy … more
Date: January 1, 1986
Creator: Yu, C.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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RESRAD. Site-Specific Residual Radioactivity

Description: RESRAD is designed to derive site-specific guidelines for allowable residual concentrations of radionuclides in soil. A guideline is defined as a radionuclide concentration or a level of radiation or radioactivity that is acceptable if a site is to be used without radiological restrictions. Guidelines are expressed as (1) concentrations of residual radionuclides in soil, (2) concentrations of airborne radon decay products, (3) levels of external gamma radiation, (4) levels of radioactivity from… more
Date: June 1, 1989
Creator: Yu, C.
Item Type: Refine your search to only Text
Partner: UNT Libraries Government Documents Department
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Spectroscopic analysis of low Z impurities in the Tandem Mirror Experiment-upgrade

Description: Two absolutely calibrated EUV instruments have been used to study the impurity characteristics in the Tandem Mirror Experiment-Upgrade (TMX-U). One instrument is a normal incidence spectrograph that measures the time histories of several impurity emission lines (300 to 1800 A) in a single shot; radial scans can be obtained on a shot-by-shot basis. The other instrument is a monochromator that measures time-resolved radial profiles of a given impurity emission line in a single shot. The common in… more
Date: September 1, 1986
Creator: Yu, T.L.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Atomic data needs for beam transport in gas

Description: Determination of the parameters Z/sub eff/, electrical conductivity, plasma density, and the plasma temperature is essential in the study of heavy ion beam transport in gas. The calculation of these parameters require input from atomic physics. This note is an attempt to make these needs known to atomic physicists.
Date: November 3, 1977
Creator: Yu, S. S.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Solvolytic liquefaction of wood under mild conditions

Description: Conversion of wood to liquid products requires cleavage of bonds which crosslink the wood structure. This study examines a low-severity wood solubilization process utilizing a solvent medium consisting of a small amount of sulfuric acid and a potentially wood-derivable alcohol. In one half hour of reaction time at 250/sup 0/C under 15 psia starting nitrogen pressure, over 95% of the wood (maf) was rendered acetone-soluble. The product is a soft, black, bitumen-like solid at room temperature but… more
Date: April 1, 1982
Creator: Yu, S.M.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Intense electron beams

Description: This paper is concerned with intense electron beams, typically of the order of a few kA in current and up to tens of MeV in beam energy. A beam of this kind can be produced from induction machines, examples of which are the ERA (4 MeV, 1 kA) at Lawrence Berkeley Laboratory and the ASTRON (5 MeV, 500A), ETA (5 MeV, 10 kA), and ATA (50 MeV, 10 kA) at Lawrence Livermore National Laboratory (LLNL). The emphasis of the paper is on the characteristics of these beams and some applications. 13 refs., 2… more
Date: October 20, 1987
Creator: Yu, S. S.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Orbit Stability and Feedback Control in Synchrotron Radiation Rings

Description: Stability of the electron orbit is essential for the utilization of a low emittance storage ring as a high brightness radiation source. We discuss the development of the measurement and feedback control of the closed orbit, with emphasis on the activities as the National Synchrotron Light Source of BNL. We discuss the performance of the beam position detectors in use and under development: the PUE rf detector, split ion chamber detector, photo-emission detector, solid state detector, and the gr… more
Date: January 1, 1989
Creator: Yu, L. H.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Effect of primary ion energy and surface chemistry on the secondary ion yields in low energy SIMS experiments

Description: The chemisorption of oxygen on W(100) and Mo(100) single crystal surfaces was studied using a static mode SIMS technique at primary ion energies ranging from 150 eV to 2 keV. The following secondary ion yields O/sup -/, WO/sub 2//sup -/, and MoO/sub 2//sup -/ were found to be sensitive to the changes in the chemisorbed oxygen layer at different stages of chemisorption. Significant enhancement in the sensitivity of the O/sup -/ yield to the chemisorption process was observed when the energy of t… more
Date: January 1, 1977
Creator: Yu, M. L.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Isotope effect in the study of H-W(100) and O-W(100) chemisorption systems using SIMS

Description: Large isotope effects were observed in the secondary ion yields when chemisorbed layers of H, D, /sup 16/O, and /sup 18/O on W(100) were sputtered with low energy Ne/sup +/ ions. Higher isotopic mass in general lowered both the atomic ion yields (H/sup -/, D/sup -/, O/sup +/ and O/sup -/) and the molecular ion yield (WO/sub 2//sup -/), except for H/sup +/(D/sup +/) where the converse was true.
Date: January 1, 1977
Creator: Yu, M. L.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Ion desorption cross section of carbon containing molecules on aluminum and stainless steel

Description: It was proposed that the ''pressure bump'' phenomenon observed in the CERN ISR proton machine is caused by ion induced desorption of gas molecules from the vacuum chamber wall.Residual gas molecules ionized by the proton beam are accelerated by the beam to wall potential (order of kV), and bombard the chamber wall with near normal incidence sputtering off molecules. Mass spectrometric analysis of the residual gas content showed that gas molecules desorbed during the pressure bump are mostly car… more
Date: January 1, 1975
Creator: Yu, M. L.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Work function dependence and isotope effect in the production of negative hydrogen ions during sputtering of adsorbed hydrogen on Cs covered Mo(100) surfaces

Description: The enhancement of the H/sup -/ yield, during sputtering of adsorbed hydrogen on a Mo(100) surface, by a Cs overlayer was investigated. An exponential dependence of the H/sup -/ yield on the work function was observed for a wide range of Cs coverages. A simple electron tunneling model was proposed. A large reduction in the ion yield was also observed when D/sub 2/ replaced H/sub 2/ as the adsorbate.
Date: January 1, 1977
Creator: Yu, M. L.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Comment on the effect of Cs on photon and secondary ion emission during sputtering

Description: The effect of Cs on photon and negative ion emission was discussed for the situations where the sputtered atom interacts either very weakly or very strongly with the target surface. The experimental data seem to favor the strong interaction case. 5 references.
Date: January 1, 1978
Creator: Yu, Ming L.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Boltzmann approach to conductivity calculations

Description: The basic set of equations is derived for the calculation of the time-dependent electrical conductivity of an initially unionized gas generated by a propagating relativistic electron beam. In contrast with previous work, which used thermal averages, conductivity is determined from the complete, nonequilibrium electron energy distribution. The evolution of the distribution function, resulting from interaction with gas molecules, ions, beam induced electric field, and beam current, is described b… more
Date: August 11, 1978
Creator: Yu, S. S.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Effect of surfactants on pressure-sensitivity of carbon nanotube filled cement mortar composites

Description: In this article, the pressure-sensitivity of CNT filled cement mortar composites with different concentrations of MWNT and different surfactants is investigated under repeated loading and impulsive loading, respectively. Experimental results indicate that the response of the electrical resistance of composites with NaDDBS to external force is more stable and sensitive than that of composites with SDS. Therefore, NaDDBS has higher efficiency than SDS for the dispersion of MWNT in cement mortar, … more
Date: November 6, 2014
Creator: Han, Baoguo & Yu, Xun
Item Type: Refine your search to only Article
Partner: UNT College of Engineering
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Cold-formed Steel Framed Shear Wall Sheathed with Corrugated Sheet Steel

Description: Incombustibility is one important advantage of the sheet steel sheathed shear wall over wood panel sheathed shear wall. Compared to shear wall sheathed with plywood and OSB panel, shear wall sheathed with flat sheet steel behaved lower shear strength. Although shear wall sheathed with corrugated sheet steel exhibited high nominal strength and high stiffness, the shear wall usually behaved lower ductility resulting from brittle failure at the connection between the sheathing to frames. This rese… more
Date: May 2013
Creator: Yu, Guowang
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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Modeling beam-front dynamics at low gas pressures

Description: The dynamics of space charge neutralization at the front of an intense self-focused electron beam pulse exhibits important differences in different gas pressure regimes. At very low pressures, the beam front is in the so-called ion-focused regime (IFR) where all secondary electrons are expelled from the beam region by the radial electric field without causing significant additional ionization. We estimate the upper pressure boundary of this regime by considering the distance scale length for ca… more
Date: May 13, 1982
Creator: Briggs, R. J. & Yu, S.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Geothermal energy development in the Eastern United States. Technical assistance report No. 4. Geothermal space heating: Pittsville Middle/Elementary School, Pittsville, Maryland

Description: A technical evaluation was made to determine whether geothermal energy obtained from a well could be used to space heat the new school building being constructed as well as the existing elementary wing of the Pittsville School. The first part deals with space heating the new school building only; the second part pertains to space heating the new school building together with the new existing wing. An addendum was added for new well and production pump costs. (MHR)
Date: June 1, 1980
Creator: Briesen, R.V. & Yu, K.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Transverse Correlations in Start-Up of a Free Electron Laser From Noise

Description: Linearized Vlasov-Maxwell equations are used to derive a partial differential equation determining the 3-dimensional slowly varying envelope function of the radiated electric field. The equation is solved analytically. From the correlation function <E(z,r,t) E*(z',r',t)> of the electric field averaged over the stochastic ansemble describing the initial shot noise in the beam, we compute the longitudinal and transverse correlation lengths sigma/sub L/ and sigma/sub T/. The radiated power S per u… more
Date: March 1, 1986
Creator: Yu, L. H. & Krinsky, S.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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