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Component performance investigation of J71 experimental turbine 8: effect of first-stator adjustment; internal flow conditions of J71-97 turbine with 70-percent-design stator area

Description: Results of a survey investigation of the J71-97 experimental three-stage turbine equipped with a first-stator area 70 percent pf design are presented and compared with the turbine with a first-stator area 97 percent of design.
Date: January 18, 1957
Creator: Petrash, Donald A.; Schum, Harold J. & Davison, Elmer H.
Partner: UNT Libraries Government Documents Department

Over-all performance of the J71 three-stage turbine

Description: Report presenting an investigation to determine the overall performance of the three-stage turbine from the J71 turbojet engine. The turbine operated with a maximum brake internal efficiency of approximately 0.84 at an equivalent overall pressure ratio of approximately 3.6 and an equivalent rotor speed of about 110 percent of the equivalent design value.
Date: July 9, 1952
Creator: Berkey, William E.
Partner: UNT Libraries Government Documents Department

Far-from-equilibrium measurements of thermodynamic length

Description: Thermodynamic length is a path function that generalizes the notion of length to the surface of thermodynamic states. Here, we show how to measure thermodynamic length in far-from-equilibrium experiments using the work fluctuation relations. For these microscopic systems, it proves necessary to define the thermodynamic length in terms of the Fisher information. Consequently, the thermodynamic length can be directly related to the magnitude of fluctuations about equilibrium. The work fluctuation relations link the work and the free energy change during an external perturbation on a system. We use this result to determine equilibrium averages at intermediate points of the protocol in which the system is out-of-equilibrium. This allows us to extend Bennett's method to determine the potential of mean force, as well as the thermodynamic length, in single molecule experiments.
Date: November 5, 2008
Creator: Feng, Edward H. & Crooks, Gavin E.
Partner: UNT Libraries Government Documents Department

Unusual flux-distance relationship for pulsars suggested by analysis of the Australia national telescopy facility pulsar catalogue

Description: We analyze pulsar fluxes at 1400 MHz (S(1400)) and distances d taken from the Australia National Telescope Facility (ATNF) Pulsar Catalogue. Under the assumption that pulsar populations in different parts of the Galaxy are similar, we find that either (a) pulsar fluxes diminish with distance according to a non-standard power law (we suggest S(1400){proportional_to} 1/d rather than {proportional_to} 1/d{sup 2}) or (b) that there are very significant (i.e. order of magnitude) errors in the distance estimates quoted in the ATNF Catalogue. The former conclusion (a) supports a recent model for pulsar emission that has also successfully explained the frequency spectrum of the Crab pulsar over 16 orders of magnitude of frequency, whilst alternative (b) would necessitate a radical re-evaluation of both the dispersion method for estimating pulsar distances and current ideas about the distribution of pulsars within our Galaxy.
Date: January 1, 2009
Creator: Singleton, John; Perez, M R; Singleton, J; Ardavan, H & Ardavan, A
Partner: UNT Libraries Government Documents Department

Effects of Pulse Duration on Bulk Laser Damage in 350-nm Raster-Scanned DKDP

Description: In this paper we present the results of bulk damage experiments done on Type-I1 DKDP triple harmonic generator crystals that were raster conditioned with 351-355 nm wavelengths and pulse durations of 4 and 23.2 ns. In the first phase of experiments 20 different scan protocols were rastered into a sample of rapid growth DKDP. The sample was then rastered at damage-causing fluences to determine the three most effective protocols. These three protocols were scanned into a 15-cm sample of conventional-growth DKDP and then exposed to single shots of a I-cm beam from LLNL's Optical Sciences Laser at fluences ranging from 0.5 - 1.5X of the 10% damage probability fluence and nominal pulse durations of 0.1,0.3,0.8,3.2,7.0 and 20 ns. The experiment showed that pulse durations in the 1-3 ns range were much more effective at conditioning than pulses in the 16.3 ns range and that the multiple pass 'peak fluence' scan was more effective than the single pass 'leading edge' scan for 23.2 ns XeF scans.
Date: October 30, 2002
Creator: Runkel, M; Bruere, J; Sell, W; Weiland, T; Milam, D; Hahn, D E et al.
Partner: UNT Libraries Government Documents Department

Long-Range Corrected Hybrid Density Functionals with Damped Atom-Atom Dispersion Corrections

Description: We report re-optimization of a recently proposed long-range corrected (LC) hybrid density functionals [J.-D. Chai and M. Head-Gordon, J. Chem. Phys. 128, 084106 (2008)] to include empirical atom-atom dispersion corrections. The resulting functional, {omega}B97X-D yields satisfactory accuracy for thermochemistry, kinetics, and non-covalent interactions. Tests show that for non-covalent systems, {omega}B97X-D shows slight improvement over other empirical dispersion-corrected density functionals, while for covalent systems and kinetics, it performs noticeably better. Relative to our previous functionals, such as {omega}B97X, the new functional is significantly superior for non-bonded interactions, and very similar in performance for bonded interactions.
Date: June 14, 2008
Creator: Chai, Jeng-Da & Head-Gordon, Martin
Partner: UNT Libraries Government Documents Department

Recent results from sage

Description: A radiochemical {sup 71}Ga-{sup 71}Ge experiment to determine the primary flux of neutrinos from the Sun began measurements of the solar neutrino flux at the Baksan Neutrino Observatory in 1990. The number of {sup 71}Ge atoms extracted from initially 30 and later 57 tons of metallic gallium was measured in fifteen runs during the period of January 1990 to May 1992. The observed capture rate is 70{plus_minus}19 (stat){plus_minus}10 (syst) SNU. This is to be compared with 132 SNU predicted by the Standard Solar Model.
Date: December 31, 1993
Creator: Gavrin, V. N.; Faizov, E. L. & Kalikhov, A. V.
Partner: UNT Libraries Government Documents Department

Component performance investigation of J71 experimental turbine 6: effect of first-stator adjustment; over-all performance of J71-97 turbine with 70-percent-design stator area

Description: Report presenting an investigation of the effect of first-stator area changes on the overall component performance of the J71-97 experimental turbine. The performance of the turbine with the first-stator area reduced to 70 percent of design by reorienting the stagger angle of the design blade profiles is presented. Results regarding the overall performance, choking characteristics, and matching characteristics are provided.
Date: October 2, 1956
Creator: Schum, Harold J.; Petrash, Donald A. & Davison, Elmer H.
Partner: UNT Libraries Government Documents Department

Exact Solution (Within a Double Zeta Basis Set) of Schrodinger's Electronic Equation for Water

Description: Using recently developed theoretical techniques, it has been possible to achieve an exact variational solution of Schrodinger's Equation within a modest basis set of one-electron functions. The full configuration interaction for this system included a total of 256,473 {sup 1}A{sub 1} spin-and space-adapted configurations. Comparison with many-body perturbation theory proves to be quite interesting.
Date: September 1, 1980
Creator: Saxe, Paul; Schaefer, Henry F., III & Handy, Nicholas C.
Partner: UNT Libraries Government Documents Department

Surface Enhanced Second Harmonic Generation

Description: Second harmonic generation at a silver-air interface was enhanced due to surface roughness by a factor of 10{sup 4}. The local field enhancement is believed to be responsible for the effect. An unusually broad luminescence background extending far beyond the antiStokes side of the second harmonic was also observed.
Date: September 1, 1980
Creator: Chen, C. K.; de Castro, A. R. B. & Shen, Y. R.
Partner: UNT Libraries Government Documents Department

Performance of 15-Stage Experimental J71 Axial-Flow Compressor: 2 - Individual Stage Performance Characteristics

Description: The first four stages were found to cause a major part of the poor low-speed efficiency of this compressor. The low design-speed over-all pressure ratio at surge was caused by the first and the twelfth to fifteenth stages. The multiple over-all performance curves in the intermediate-speed range were at least partly the result of double-branched characteristic curves for the third and seventh stages.
Date: October 29, 1954
Creator: Lucas, James G. & Filippi, Richard E.
Partner: UNT Libraries Government Documents Department

Performance of 15-Stage Experimental J71 Axial-Flow Compressor. 3 - Effects of Inlet-Guide-Vane Adjustment

Description: The stall-limit line at low speeds was improved somewhat by closing the inlet guide vanes 6 deg, while the design-speed maximum flow and pressure ratio were reduced. The first-stage characteristic curve was moved to lower values of both flog coefficient and equivalent pressure ratio. The second-stage pressure ratio was decreased slightly at high speeds, while the later stages were unaffected.
Date: April 20, 1955
Creator: Lucas, James G. & Filippi, Richard E.
Partner: UNT Libraries Government Documents Department

An Overview of Raster Scanning for ICF-Class Laser Optics

Description: Recent work has shown that the damage resistance of both ICF-class (1600 cm') DKDP tripler crystals and SiO{sub 2} components (lenses, gratings and debris shields) benefits from laser raster scanning using pulsed lasers in the 350 nm range. For laser raster scanning to be a viable optical improvement tool for these large optics, damage improvement must be optimized while maintaining scan times of less than 8 hours/optic. In this paper we examine raster scanning with small beams from tabletop laser systems. We show that 120 Watts of average power is required for a tabletop scanning system at one optic/day. Next, we develop equations for total scan time for square and round top hat beams and round and rectangular Gaussian beams. We also consider the effect of packing geometry (square vs. hexagonal), examine the deviations from uniform coverage with each scan geometry and show that hexagonal packing yields lower scan times but is less efficient in coverage than square geometry. We also show that multiple passes at low packing densities are temporally equivalent to a single pass with higher packing density, and discuss the advantages of each method. In addition, we show that the differences between hexagonal and square scan geometries are negated when pointing errors and fluence fluctuations from the laser are considered.
Date: October 30, 2002
Creator: Runkel, M J & Nostrand, M
Partner: UNT Libraries Government Documents Department

PHOTOTHERMAL DEFLECTION SPECTROSCOPY AND DETECTION

Description: The theory for a sensitive spectroscopy based on the photothermal deflection of a laser beam is developed. We consider cw and pulsed cases of both transverse and collinear photothermal deflection spectroscopy for solids, liquids, gases, and thin films. The predictions of the theory are experimentally verified, its implications for imaging and microscopy are given, and the sources of noise are analyzed. The sensitivity and versatility of photothermal deflection spectroscopy are compared with thermal lensing and photoacoustic spectroscopy.
Date: September 1, 1980
Creator: Jackson, W.; Amer, Nabil M.; Boccara, A. C. & Fournier, D.
Partner: UNT Libraries Government Documents Department

THERMAL RADIATION OF SPHERICAL AND CYLINDRICAL SOOT PARTICLES

Description: The effect of soot shape on soot radiation from flame and smoke is considered in the present study. It is realized that soot particles generally conglomerate into different shapes. while the limiting bounds are being either spherical or long chains. By modellirig the long chains as infinite cylinders, it is shown that the radiation extinction characteristics of the spherical and cylindrical soot are distinctly different, with that of the spherical particles exhibiting a cut-off wavelength phenomenon. Emissivity from a cloud of cylindrical particles is always higher than that of the spheres due to their higher extinction coefficients. Moreover, the effect of soot shape onradiation is more pronounced at typical smoke temperatures (300°K) than at flame temperatures. A simple experimental method is also proposed for determining the amount of cylindrical and spherical particles in a cloud.
Date: October 1, 1980
Creator: Lee, S. C. & Tien, C. L.
Partner: UNT Libraries Government Documents Department

STRONG COUPLING EXPANSIONS FOR NON-INTEGRABLE HAMILTONIAN SYSTEMS

Description: We present a method for studying nonintegrable Hamiltonian systems H(I,{theta})=H{sub 0}(I)+kH{sub 1}(I,{theta}) (I,{theta} are action-angle variables) in the reg1me of large k. Our central tool is the conditional probability P(I,{theta},t|I{sub 0},{theta}{sub 0},t{sub 0}) that the system is at I,{theta} at time t given that it resided at I{sub 0},{theta}{sub 0} at t{sub 0}. An integral representation is given for this conditional probability. By discretizing the Hamiltonian equations of motion in small time steps, {epsilon}, we arrive at a phase volume preserving mapping which replaces the actual flow. When the motion on the energy surface E=H(I,{theta}) is bounded we are able to evaluate physical quantities of interest for large k and fixed {epsilon}. We also discuss the representation of P(I,{theta},t|I{sub 0},{theta}{sub 0},t{sub 0}) when an external random forcing is added in order to smooth the singular functions associated with the deterministic flow. Explicit calculations of a "diffusion" coefficient are given for a non-integrable system with two degrees of freedom. The limit {epsilon}{approaches}0 , which returns us to the actual flow, is subtle and is discussed.
Date: December 1, 1980
Creator: Abarbanel, Henry D.I. & Crawford, John David
Partner: UNT Libraries Government Documents Department

DIFFUSION IN VERY CHAOTIC HAMILTONIAN SYSTEMS

Description: We study nonintegrable Hamiltonian dynamics: H(I,{theta}}) = H{sub 0}(I)+kH{sub 1}(I,{theta}) for large k; that is, far from integrability. An integral representation is given for the conditional probability P(I,{theta},t|I{sub 0},{theta}{sub 0},t{sub 0}) that the system is at I,{theta} at t, given it was at I{sub 0},{theta}{sub 0} at t{sub 0}. By discretizing time into steps of size {epsilon}, we show how to evatuate physical observables for large k, fixed {epsilon}. An explicit calculation of a diffusion coefficient in a two degree of freedom problem is reported. Passage to {epsilon} = 0, the original Hamiltonian flow, discussed.
Date: December 1, 1980
Creator: Abarbanel, Henry D.I. & Crawford, John David
Partner: UNT Libraries Government Documents Department