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The Dielectric Constant of Galvinoxyl

Description: The molecules in many substances are know to undergo at characteristic temperatures a change in their rotational freedom in the solid state, signifying either a change in structure of the material of the onset of limited rotation of the molecule about some symmetry axis. The purpose of this research was to determine from dielectric constant measurements over the 100°K-420°K temperature range whether or not the organic free radical galvinoxyl and its diamagnetic parent molecule, dihydroxydiphenylmethane, undergo any such transitions.
Date: May 1968
Creator: Mizell, Michael E.
Partner: UNT Libraries

Electrodeposit of Nickel

Description: The purpose of this study is to investigate the varying conditions in types of solutions, concentrations of solutions, hydrogen-ion concentration, current densities and potentials in the electro deposition of nickel.
Date: August 1937
Creator: Rohrer, Charles Stephen
Partner: UNT Libraries

An Experimental Study of the Electrodeposition of Lead

Description: This thesis aimed to study some of the general principles underlying electrodeposition together with experimental facts regarding the effects of changing constituents of the plating solutions, variations in hydrogen-ion concentrations, and variation in current density used in the electrodeposition of lead.
Date: June 1937
Creator: Roberts, Ira Clifford
Partner: UNT Libraries

Two-Dimensional Carrier-Carrier Screening in a Quantum Well

Description: The behavior of carrier-carrier screening is investigated in a GaAs-GaAIAs quantum well structure by measuring the band-to-band polarization dephasing with femtosecond photon echoes. The variation of the electron-hole polarization dephasing time with the carrier concentration reveals the two-dimensional character of the short range screening between the interacting carriers.
Date: July 1, 1991
Creator: Bigot, J.-Y.; Portella, M.T.; Schoenlein, R.W.; Cunningham, J.E. & Shank, C.V.
Partner: UNT Libraries Government Documents Department


Description: Based on this workshop, a plan for upgrading polarized proton acceleration in the AGS was developed. The construction of a strong partial Siberian snake was initiated. Although in principle this single device would avoid all sources of depolarization in the AGS its construction, installation and commissioning will take several years. Also mismatch of the polarization direction at injection into the AGS will cause some depolarization. Plan 1 outlined above will be pursued in the meantime. A warm helical partial Siberian snake will replace the present solenoid snake. It will avoid the coupling resonances and can also be used in the future to avoid injection mismatch with the strong partial snake. Existing quadrupoles will be moved to locations where they can be used to suppress the weak intrinsic resonances as discussed at this workshop by Andreas Lehrach. This approach should give maximum polarization from the AGS as soon as possible and also provide a long term solution that is operationally simple and offers additional polarization improvements if the rf dipole method shows residual depolarization.
Date: November 6, 2002
Creator: ROSER,T.
Partner: UNT Libraries Government Documents Department

Design and Manufacture of Molding Compounds for High Reliability Microelectronics in Extreme Conditions

Description: The widespread use of electronics in more avenues of consumer use is increasing. Applications range from medical instrumentation that directly can affect someone's life, down hole sensors for oil and gas, aerospace, aeronautics, and automotive electronics. The increased power density and harsh environment makes the reliability of the packaging a vital part of the reliability of the device. The increased importance of analog devices in these applications, their high voltage and high temperature resilience is resulting in challenges that have not been dealt with before. In particular packaging where insulative properties are vital use polymer resins modified by ceramic fillers. The distinct dielectric properties of the resin and the filler result in charge storage and release of the polarization currents in the composite that have had unpredictable consequences on reliability. The objective of this effort is therefore to investigate a technique that can be used to measure the polarization in filled polymer resins and evaluate reliable molding compounds. A valuable approach to measure polarization in polymers where charge release is tied to the glass transition in the polymer is referred to as thermally stimulated depolarization current (TSDC) technique. In this dissertation a new TSDC measurement system was designed and fabricated. The instrument is an assembly of several components that are automated via a LabVIEW program that gives the user flexibility to test different dielectric compounds at high temperatures and high voltage. The temperature control is enabled through the use of dry air convection heating at a very slow rate enabling controlled heating and cooling. Charge trapping and de-trapping processes were investigated in order to obtain information on insulating polymeric composites and how to optimize it. A number of material properties were investigated. First, polarization due to charges on the filer were investigated using composites containing charged and uncharged particles using ...
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Date: December 2016
Creator: Garcia, Andres
Partner: UNT Libraries

Methods of Calculation of Resistance to Polarization (Corrosion Rate) Using ASTM G 59

Description: The corrosion rate of a metal (alloy) can be measured using: (1) Immersion tests or weight loss such as in ASTM G 1 and G 31 or (2) Electrochemical techniques such as in ASTM G 59. In the polarization resistance (PR) or linear polarization method (G 59), the resistance to polarization (Rp) of a metal is measured in the electrolyte of interest in the vicinity of the corrosion potential (E{sub corr}). This polarization resistance can be mathematically converted into corrosion rates (CR). A plot of E vs. I in the vicinity of E{sub corr} is generated by increasing the potential at a fixed rate of 0.1667 mV/s and measuring the output current. The polarization resistance (Rp) is defined as the slope of a potential (E) (Y axis) vs. Current (I) (X axis) plot in the vicinity of the corrosion potential (E{sub corr}). When the potential is ramped and the current is measured, E is the independent variable and I is the dependent variable. In a proper mathematical plot, E should be represented in the X axis and I in the Y axis. However, in the conventions of the corrosion community, E is always plotted in the Y axis and I in the X axis. Therefore, how this plot of Delta E/Delta I is analyzed is a matter of current debate.
Date: February 5, 2006
Creator: Wong, L L; King, K J; Martin, S I & Rebak, R B
Partner: UNT Libraries Government Documents Department

Direct Measurements of an increased threshold for stimulated Brillouin scattering with polarization smoothing in ignition hohlraum plasmas

Description: We demonstrate a significant reduction of stimulated Brillouin scattering by polarization smoothing. The intensity threshold is measured to increase by a factor of 1.7 {+-} 0.2 when polarization smoothing is applied. The results were obtained in a high-temperature (T{sub 3} {approx_equal} 3 keV) hohlraum plasma where filamentation is negligible in determining the backscatter threshold. These results are explained by an analytical model relevant to ICF plasma conditions that modifies the linear gain exponent to account for polarization smoothing.
Date: November 8, 2007
Creator: Froula, D; Divol, L; Berger, R L; London, R; Meezan, N; Neumayer, P et al.
Partner: UNT Libraries Government Documents Department

qSF wavefront triplication in a transversely isotropicmaterial

Description: Triplication of a wavefront, also classically known as birefringence, can and does occur in transversely isotropic (TI) media. With the growing interest in shear waves, and in particular, converted shear waves, it becomes necessary to study this phenomenon, and the bright spots that accompany it. In a plane that includes the medium's rotational symmetry axis, there may exist a range of angles within which the qSV wave, whose polarization lies in that plane, may propagate at three distinct velocities. The region of the qSV wave curve where this can occur always corresponds to the region of the qSV slowness curve where the closed qSV curve about the origin is concave. When the range of angles is small and the three arrivals are close together, the usual situation, the qSV wave within that small range will be significantly brighter than in other directions. When the range of angles is large, the two cusps of the wave surface, on the borders of the region of triplication will both be bright spots.
Date: June 1, 2004
Creator: Schoenberg, Michael & Daley, Thomas M.
Partner: UNT Libraries Government Documents Department


Description: The stable spin direction in the RHIC rings is vertical. With one or two partial helical Siberian snakes in the AGS, the stable spin direction at extraction is not vertical. Interleaved vertical and horizontal bends in the transport line between AGS and the RHIC rings also tend to tip the spin away from the vertical. In order to maximize polarization in RHIC, we examined several options to improve the matching of the stable spin direction during beam transfer from the AGS to each of the RHIC rings. While the matching is not perfect, the most economical method appears to be a lowering of the injection energy by one unit of G{gamma} from 46.5 to 45.5.
Date: June 23, 2006
Partner: UNT Libraries Government Documents Department

p-Carbon polarimetry at RHIC.

Description: The polarization measurement through elastic ({rvec p},C) reaction plays a crucial role in the polarized proton beam operation of Relativistic Heavy Ion collider at Brookhaven National Laboratory. As well as measuring the polarization, the unknown analyzing power A{sub N} of elastic ({rvec p},C) is determined as well in combination with the absolute polarization measurement by a H-jet polarimeter. The systematic uncertainty of the Run05 measurements are discussed as well as introducing the experimental apparatus of the polarimeter system.
Date: September 10, 2007
Creator: Nakagawa,I.; Makdisi,Y.; Alekseev, I.; Bazilesky, A.; Bravar, A.; Bunce, G. et al.
Partner: UNT Libraries Government Documents Department

Measurement of G

Description: The ratio of the electric and magnetic form factors of the proton, G{sub E{sub p}}/G{sub M{sub p}}, was measured at the Thomas Jefferson National Accelerator Facility (JLab) using the recoil polarization technique. The ratio of the form factors is directly proportional to the ratio of the transverse to longitudinal components of the polarization of the recoil proton in the elastic {rvec e}p {yields} e{rvec p} reaction. The new data presented in this article span the range 3.5 < Q{sup 2} < 5.6 GeV{sup 2} and are well described by a linear Q{sup 2} fit. Also, the ratio QF{sub 2p}/F{sub 1p} reaches a constant value above Q{sup 2}=2 GeV{sup 2}.
Date: March 1, 2002
Creator: Gayou, Olivier; Brash, Ed J.; Jones, Mark K.; Perdrisat, Charles F.; Punjabi, Vina; Pentchev, L. et al.
Partner: UNT Libraries Government Documents Department

Polarization Dependence of the Spin-Density-Wave Excitations in Single-Domain Chromium

Description: A polarised neutron scattering experiment has been performed on a single-Q, single domain sample of Cr in a magnetic field of 4 T in the transverse spin-density-wave phase. It is confirmed that the longitudinal fluctuations are enhanced for energy transfers E {lt} 8 meV similarly as in the longitudinal spin-density-wave phase. The spin wave modes with deltaS parallel and perpendicular to Q are isotropic within the E-range investigated.
Date: December 31, 1997
Creator: Boeni, P.; Sternlieb, B.J.; Shirane, G.; Roessli, B.; Werner, S.A. & Lorenzo, J.E.
Partner: UNT Libraries Government Documents Department

Handbook of Accelerator Physics and Engineering (sections 2.7.1 - 2.7.5 and 7.6.2)

Description: The sections written by this author are: 2.7.1- Thomas - BMT equation; 2.2.2- Spinor Algebra; 2.7.3- Spin Rotators and Siberian Snakes; 2.7.4- Ring with Spin Rotator and Siberian Snakes; 2.7.5- Depolarizing Resonances and Spin Flippers; & 7.6.2- Proton Beam Polarimeters
Date: April 19, 1999
Creator: Roser, T.
Partner: UNT Libraries Government Documents Department

Effect of Nitrite/Nitrate concentrations on Corrosivity of Washed Precipitate

Description: Cyclic polarization scans were performed using A-537 carbon steel in simulated washed precipitate solutions of various nitrite and nitrate concentrations. The results of this study indicate that nitrate is an aggressive anion in washed precipitate. Furthermore, a quantitative linear log-log relationship between the minimum effective nitrite concentration and the nitrate concentration was established for washed precipitate with other ions at their average compositions.
Date: March 28, 2001
Creator: Congdon, J.W.
Partner: UNT Libraries Government Documents Department

Practical Point-to-Point Free-Space Quantum Key Distribution over 1/2 KM

Description: We have demonstrated point-to-point single-photon quantum key distribution (QKD) over a free-space optical path of {approximately}475 m under daylight conditions. This represents an increase of >1,000 times farther than any reported point-to-point demonstration, and >6 times farther than the previous folded path daylight demonstration. We expect to extend the daylight range to 2 km or more within the next few months. A brief description of the system is given here. The QKD transmitter, a.k.a. ''Alice'' (Fig. 1), consists of three thermoelectrically cooled diode lasers, a single interference filter (IF), two optical attenuators, two linear polarizers, two non-polarization beam-splitters (BSs), and a 27x beam expander. The two data-lasers' (dim-lasers') wavelengths are temperature controlled and constrained by the IF to {approximately}773 {+-} 0.5 nm, while the transmitted wavelength of the bright-laser (timing-laser) is {approximately}768 nm; the data-lasers are configured to emit a weak pulse of approximately 1 ns duration. The transmitter incorporates no active polarization switching--a first in QKD.
Date: February 1, 1999
Creator: Buttler, W.T.; Hughes, R.J.; Kwiat, P.G.; Lamoreaux, S.K.; Morgan, G.L. & Peterson, C.G.
Partner: UNT Libraries Government Documents Department