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Free-spinning wind-tunnel tests of a low-wing monoplane with systematic changes in wings and tails V: effect of airplane relative density

Description: The reported tests are a continuation of an NACA investigation being made in the free-spinning wind tunnel to determine the effects of independent variations in load distribution, wing and tail arrangement, and control disposition on the spin characteristics of airplanes. The standard series of tests was repeated to determine the effect of airplane relative density. Tests were made at values of the relative-density parameter of 6.8, 8.4 (basic), and 12.0; and the results were analyzed. The tested variations in the relative-density parameter may be considered either as variations in the wing loading of an airplane spun at a given altitude, with the radii of gyration kept constant, or as a variation of the altitude at which the spin takes place for a given airplane. The lower values of the relative-density parameter correspond to the lower wing loadings or to the lower altitudes of the spin.
Date: January 11, 1940
Creator: Seidman, Oscar & Neihouse, A. I.
Partner: UNT Libraries Government Documents Department

An analytical investigation of airplane spin-recovery motion by use of rotary-balance aerodynamic data

Description: From Introduction: "Many investigations have been made in the Langley 20-foot free-spinning tunnel in which the natures of airplane spins and recoveries have been determined experimentally with dynamically scaled-down models. The results of some of these investigations are presented in references 1 to 5."
Date: June 1954
Creator: Scher, Stanley H
Partner: UNT Libraries Government Documents Department

Analytical determination of the mechanism of an airplane spin recovery with different applied yawing moments by use of rotary-balance data

Description: From Introduction: "These aerodynamic data were used previously in an analytical investigation of a spin recovery by rudder reversal, the results of which have been published in reference 2. Because of certain discrepancies in the rotary-balance data similar to those discussed in reference 3, some modifications were made to the aerodynamic data used in calculating the results in reference 2 and also the results in this paper; these discrepancies and modifications are discussed in detail herein."
Date: December 1954
Creator: Burk, Sanger M., Jr.
Partner: UNT Libraries Government Documents Department

Mathematical treatise on the recovery from a flat spin

Description: In this mathematical investigation, made in collaboration with Dr. Wilhelm Schmidt, we interpret the temporary change (due to some disturbance) in the quantities which define the position of the airplane while in a flat spin. We further examine the effect of this change, of the means resorted to to produce the disturbance, and thus reveal the expedients available for recovering from a flat spin.
Date: November 1930
Creator: Fuchs, R.
Partner: UNT Libraries Government Documents Department

THE TWO-LEVEL MODEL AT FINITE-TEMPERATURE

Description: The finite-temperature HFB cranking equations are solved for the two-level model. The pair gap, moment of inertia and internal energy are determined as functions of spin and temperature. Thermal excitations and rotations collaborate to destroy the pair correlations. Raising the temperature eliminates the backbending effect and improves the HFB approximation.
Date: July 1, 1980
Creator: Goodman, A.L.
Partner: UNT Libraries Government Documents Department

Comparison of effects of ailerons and combinations of spoiler-slot-deflector arrangements on spin recovery of sweptback-wing model having mass distributed along the fuselage

Description: Report presenting an investigation in the free-spinning tunnel to determine the effect of lateral-control systems using various combinations of spoilers, slots, and deflectors as compared with ailerons on the spin-recovery characteristics of a model of a 35 degree swept-wing fighter loaded heavily along the fuselage. Testing indicated that the ailerons were favorable for recovery when they were deflected full with the spin. Results regarding the effect of ailerons and two spoiler-slot-deflector configurations are provided.
Date: November 24, 1954
Creator: Healy, Frederick M. & Klinar, Walter J.
Partner: UNT Libraries Government Documents Department

Comparison of model and full-scale spin recoveries obtained by use of rockets

Description: Report presenting an investigation of a 1/19-scale model of an unswept-wing trainer airplane in the 20-foot free-spinning tunnel to determine the rocket spin-recovery characteristics of the model for comparison with available full-scale-airplane results. A rocket was attached to each wing tip to fire in a direction to apply an antispin yawing moment about the Z body axis. Results regarding the full-scale spin recoveries by rockets, model spin recoveries by rudder reversal, model spin recoveries by rockets, and mass changes associated with installation of emergency device are provided.
Date: February 1954
Creator: Burk, Sanger M., Jr. & Healy, Frederick M.
Partner: UNT Libraries Government Documents Department

Spin-tunnel investigation to determine the effect on spin recoveries of reducing the opening shock load of spin-recovery parachutes

Description: Report presenting an investigation in the 20-foot free-spinning tunnel to determine whether the effectiveness of a spin-recovery parachute would be influenced by a reduction, through the use of a shock absorber, or the opening shock load. The results indicated that a given spin-recovery parachute was effective with or without a rubber shock absorber installed in the parachute towline. Results regarding the effect of the shock absorber on spin-recovery characteristics and effect of porosity and towline length on shock load are provided.
Date: March 1950
Creator: Jones, Ira P., Jr. & Klinar, Walter J.
Partner: UNT Libraries Government Documents Department

Azimuthal and single spin asymmetry in deep-inelasticlepton-nucleon scattering

Description: The collinear expansion technique is generalized to thefactorization of unintegrated parton distributions and other higher twistparton correlations from the corresponding collinear hard parts thatinvolve multiple parton final state interaction. Such a generalizedfactorization provides a consistent approach to the calculation ofinclusive and semi-inclusive cross sections of deep-inelasticlepton-nucleon scattering. As an example, the azimuthal asymmetry iscalculated to the order of 1/Q in semi-inclusive deeply inelasticlepton-nucleon scattering with transversely polarized target. Anon-vanishing single-spin asymmetry in the "triggered inclusive process"is predicted to be 1/Q suppressed with a part of the coefficient relatedto a moment of the Sivers function.
Date: September 21, 2006
Creator: Liang, Zuo-tang & Wang, Xin-Nian
Partner: UNT Libraries Government Documents Department

Solid-state NMR studies for DC 745: April--May 2000

Description: Powles et al. reported in 1961 that pdydimethyl siloxane melts exhibit a transverse decay of nuclear spin magnetization (T{sub 2}) that is nonexponential. This observation was interpreted in terms of the proton NMR signal from the melt having characteristics of a broad line. Since then, similar findings were obtained for other polymer melts too. Accordingly to Powles et al. this peculiar proton line shape was the result of an intramolecular direct dipole-dipole interaction between a pair of protons. They also suggested that this dipolar interaction was weak because the dipolar interaction was motionally averaged since the orientation-dependent local dipolar field is modulated by molecular dynamics. In sum, the consequences and the origins of nuclear spin correlations in viscous polymer melts were recognized almost 4 decades ago. In the 1970s, Cohen-Addad suggested that these weak proton dipolar interactions could be used to characterize polymer melts and networks. In this work, we have used some of these ideas to probe the effects of thermal treatments on the proton spin-spin relaxation times for DC745.
Date: December 1, 2000
Creator: Stephens, T. & Labouriau, A.
Partner: UNT Libraries Government Documents Department

Spin Spectrometer at the ALS and APS

Description: A spin-resolving photoelectron spectrometer, the"Spin Spectrometer," has been designed and built. It has been utilized at both the Advanced Light Source in Berkeley, CA, and the Advanced Photon Source in Argonne, IL. Technical details and an example of experimental results are presented here.
Date: April 20, 2007
Creator: Laboratory, Lawrence Livermore National; Missouri-Rolla, University of; Technologies, Boyd; Morton, Simon A; Morton, Simon A; Tobin, James G et al.
Partner: UNT Libraries Government Documents Department

Unvail the Mysterious of the Single Spin Asymmetry

Description: Single transverse-spin asymmetry in high energy hadronic reaction has been greatly investigated from both experiment and theory sides in the last few years. In this talk, I will summarize some recent theoretical developments, which, in my opinion, help to unvail the mysterious of the single spin asymmetry.
Date: January 5, 2010
Creator: Yuan, Feng
Partner: UNT Libraries Government Documents Department

NMR DOUBLE QUANTUM SPIN DECOUPLING IN SOLIDS

Description: The problem of spin decoupling spin I = 1 nuclei with large quadrupolar splittings {omega}{sub Q} (e.g. deuterium) from dilute S spins via double quantum transitions is dealt with. The normal two spin-1/2 single quantum decoupling problem (I = 1/2, S = 1/2) is first dealt with as a reminder of the coherent averaging approach and to understand the dependence of the S resonance linewidth on the I rf field intensity ({omega}{sub 1}) and resonance offset ({Delta}{omega}). The double quantum problem (I = 1, S = 1/2) is then treated analogously by introducting fictitious spin-1/2 operators for the I double quantum transition. The decoupling condition is found to be very sensitive to the spin-I resonance condition and to go as {approx} 1/4 with the spin I rf field intensity at resonance in the double quantum regime ({omega}{sub 1} << {omega}{sub Q}). Experimental examples on heavy ice, dimethyl-sulfoxide-d{sub 6} and benzene-d{sub 6} are presented verifying the quantitative theoretical predictions. Extensions to higher order multiple quantum effects for spin I > I and for several coupled spin-1/2 nuclei are discussed.
Date: October 1, 1977
Creator: Pines, A.; Vega, S. & Mehring, M.
Partner: UNT Libraries Government Documents Department

Transverse Spin Physics: Recent Developments

Description: Transverse-spin physics has been very active and rapidly developing in the last few years. In this talk, I will briefly summarize recent theoretical developments, focusing on the associated QCD dynamics in transverse spin physics.
Date: December 10, 2008
Creator: Yuan, Feng
Partner: UNT Libraries Government Documents Department

Monte Carlo without chains

Description: A sampling method for spin systems is presented. The spin lattice is written as the union of a nested sequence of sublattices, all but the last with conditionally independent spins, which are sampled in succession using their marginals. The marginals are computed concurrently by a fast algorithm; errors in the evaluation of the marginals are offset by weights. There are no Markov chains and each sample is independent of the previous ones; the cost of a sample is proportional to the number of spins (but the number of samples needed for good statistics may grow with array size). The examples include the Edwards-Anderson spin glass in three dimensions.
Date: December 12, 2007
Creator: Chorin, Alexandre J.
Partner: UNT Libraries Government Documents Department

Effect of various errors on the Spin Tune and Stable Spin Axis

Description: Even though RHIC has two full Siberian snakes in each ring, there are various perturbations to the ideal case including orbit errors at the snakes, experiment solenoids, injection bumps, and interlaced horizontal-vertical bumps at the hydrogen jet polarimeter. These errors can cause depolarization by shifting the spin tune and tilting the stable spin direction away from vertical. Tilting of the stable spin axis can enhance horizontal depolarizing resonances. This paper presents preliminary results for some of these error scenarios, as well as their impact on the stable spin directions at STAR and PHENIX.
Date: October 6, 2008
Creator: MacKay,W.W.
Partner: UNT Libraries Government Documents Department

SPIN-TORQUE IN SYSTEMS WITH INHOMOGENEOUS MAGETIZATION

Description: The work performed during the grant period focused on the phenomenon of spin-transfer torque. This is a quantum mechanical effect whereby the angular momentum of conduction electrons is transferred to the magnetization of ferromagnetic structures. Our work on this subject began with phenomenological drift-diffusion and Landau-Lifshitz-Gilbert equations to demonstrate unambiguously that unpolarized current flow from a nonmagnet into a ferromagnet can produce a precession-type instability of the magnetization. We then used Boltzmann calculations appropriate to spin-valve type magnetic heterostructures composed of a non-magnetic thin film sandwiched between two thin film layers with uniform magnetization. Perhaps our most important paper dealt with quantum and semi-classical calculations of spin-transfer torque in systems with domain walls and other inhomogeneous distributions of magnetization. The latter work caused us to suggest that the Landau-Lifshitz approach to magnetic damping provided a clearer picture of the physics than the more popular (but formally equivalent) Gilbert approach to damping. Finally, we returned to our Boltzmann calculations and made a serious effort to analyze experimental data on current-induced magnetization in switching in magnetic spin-valve structures. Our work was part of a world-wide effort to study and harness the transport of the electron's spin and was one of the first sustained theoretical efforts in this direction in the United States. The payoff is just now being seen. In November of 2012, the Everspin Corporation announced the release of the first commercial spin-torque magnetoresistive random access memory.
Date: April 23, 2013
Creator: Zangwill, Andrew
Partner: UNT Libraries Government Documents Department

NUCLEAR SHAPES AT HIGH ANGULAR MOMENTUM

Description: Multiplicities as a function of {gamma}-ray energy have been measured for continuum {gamma}-ray spectra produced in argon- and calcium-induced reactions. A peak sometimes occurs in the multiplicity spectrum, indicating a correlation between {gamma}-ray energy and multiplicity (spin). This correlation can be explained by rotational motion of the nucleus, suggesting basically prolate nuclear shapes. Absence of structure in the multiplicity spectrum is interpreted to indicate non-collective motion, and hence spherical or oblate shapes.
Date: December 1, 1977
Creator: Deleplanque, M.A.; Lee, I.Y.; Stephens, F.S.; Diamond, R.M. & Aleonard, M.M.
Partner: UNT Libraries Government Documents Department

Orbital-optimized opposite-spin scaled second order correlation: An economical method to improve the description of open-shell molecules

Description: Coupled cluster methods based on Brueckner orbitals are well-known to resolve the problems of symmetry-breaking and spin-contamination that are often associated with Hartree-Fock orbitals. However their computational cost is large enough to prevent application to large molecules. Here they present a simple approximation where the orbitals are optimized with the mean-field energy plus a correlation energy taken as the opposite-spin component of the second order many-body correlation energy, scaled by an empirically chosen parameter (recommended as 1.2 for general applications). This optimized 2nd order opposite spin (abbreviated as O2) method requires fourth order computation on each orbital iteration. O2 is shown to yield predictions of structure and frequencies for closed shell molecules that are very similar to scaled second order Moller-Plesset methods. However it yields substantial improvements for open shell molecules, where problems with spin-contamination and symmetry breaking are shown to be greatly reduced.
Date: January 1, 2007
Creator: Lochan, Rohini C. & Head-Gordon, Martin
Partner: UNT Libraries Government Documents Department

Experimental Mathematics and Mathematical Physics

Description: One of the most effective techniques of experimental mathematics is to compute mathematical entities such as integrals, series or limits to high precision, then attempt to recognize the resulting numerical values. Recently these techniques have been applied with great success to problems in mathematical physics. Notable among these applications are the identification of some key multi-dimensional integrals that arise in Ising theory, quantum field theory and in magnetic spin theory.
Date: June 26, 2009
Creator: Bailey, David H.; Borwein, Jonathan M.; Broadhurst, David & Zudilin, Wadim
Partner: UNT Libraries Government Documents Department

Domain wall dynamics in a spin-reorientation transition system Au/Co/Au

Description: We report measurements of domain wall dynamics in an ultrathin Au/Co/Au system that exhibits a spin reorientation phase transition as a function of temperature.The domain walls exhibit cooperative motion throughout the temperature range of 150 - 300 K. The decay times were found to exhibit a maximum at the transition temperature. The slowdown has been explained as due to formation of a double well in the energy landscape by the different competing interactions. Our results show that the complex, slow dynamics can provide a more fundamental understanding of magnetic phase transitions.
Date: May 14, 2009
Creator: Roy, Sujoy; Seu, Keoki; Turner, Joshua J.; Park, Sungkyun; Kevan, Steve & Falco, Charles M.
Partner: UNT Libraries Government Documents Department

Magnetic structure near the Co/NiO(001) interface

Description: We investigate the magnetic coupling at the Co/NiO interface using soft x-ray magnetic linear dichroism (XMLD) and circular dichroism taking explicitly into account the recently observed angular dependence of the XMLD with respect to the crystallographic axes. We find that the Co moments are aligned perpendicular to the NiO moments. We discuss the impact of the anisotropic XMLD on the intensity ratio of the two peaks at the Ni L{sub 2} edge, which is commonly employed to determine the spin orientation in antiferromagnets using XMLD.
Date: August 29, 2008
Creator: Arenholz, Elke; van der Laan, Gerrit & Nolting, Frithjof
Partner: UNT Libraries Government Documents Department