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Sample records for c15 friauf-laves phase

  1. Site occupancies in ternary C15 ordered Laves phases

    SciTech Connect

    Kotula, P.G.; Chu, F.; Thoma, D.J.; Mitchell, T.E.; Anderson, I.M.; Bentley, J.

    1996-12-31

    Site occupancies in three C15-structured AB{sub 2}(X) Laves phases have been determined by Atom Location by CHanneling Enhanced MIcroanalysis (ALCHEMI). In NbCr{sub 2}(V), the results were consistent with exclusive site occupancies of Nb for the A sublattice and Cr and V for the B sublattice. The B-site occupancy of V is not expected from atom size effects alone. In NbCr{sub 2}(Ti), the results were consistent with Ti partitioning mostly to the A sites with some anti-site defects likely. In HfV{sub 2}(Nb), the results were consistent with Nb partitioning between the A and B sites. The results of the ALCHEMI analyses of these ternary C15 Laves phase materials will be discussed with respect to previously determined phase diagrams and first-principles total energy and electronic structure calculations.

  2. Stability of self-interstitial clusters with C15 Laves phase structure in iron

    NASA Astrophysics Data System (ADS)

    Dézerald, L.; Marinica, M.-C.; Ventelon, Lisa; Rodney, D.; Willaime, F.

    2014-06-01

    The energetics and stability of self-interstitial clusters with C15 Laves phase structure in iron are investigated by Density Functional Theory (DFT) calculations. First, the properties of bulk C15 are examined. The C15 structure is shown to be mechanically and dynamically stable. Second, the influence of the calculation scheme on the energy difference between C15, ring and loop configurations of di-, tri-, tetra- and octa-interstitial clusters is studied. These calculations confirm that, according to DFT, the C15 structure has by far the lowest energy of all known configurations of tetra- and octa-interstitial clusters in bcc-Fe.

  3. Irradiation-Induced Formation of Nanocrystallites with C15 Laves Phase Structure in bcc Iron

    NASA Astrophysics Data System (ADS)

    Marinica, M.-C.; Willaime, F.; Crocombette, J.-P.

    2012-01-01

    A three-dimensional periodic structure is proposed for self-interstitial clusters in body-centered-cubic metals, as opposed to the conventional two-dimensional loop morphology. The underlying crystal structure corresponds to the C15 Laves phase. Using density functional theory and interatomic potential calculations, we demonstrate that in α-iron these C15 aggregates are highly stable and immobile and that they exhibit large antiferromagnetic moments. They form directly in displacement cascades, and they can grow by capturing self-interstitials. They thus constitute an important new element to account for when predicting the microstructural evolution of iron base materials under irradiation.

  4. Technetium Incorporation into C14 and C15 Laves Intermetallic Phases

    SciTech Connect

    Buck, Edgar C.; Schemer-Kohrn, Alan L.; Wierschke, Jonathan B.

    2013-01-23

    Laves-type intermetallics have been observed to be the dominant phases in a series of alloy compositions being designed for the immobilization technetium in a metallic waste form. The dominant metals in the alloy compositions were Fe-Mo and Fe-Mo-Zr. Alloy composition, Fe-Mo-Zr, also contained Pd, Zr, Cr, and Ni. Both non-radioactive rhenium-containing and radioactive technetium-bearing alloy compositions were investigated. In the Fe-Mo series, phases were observed Fe2Mo (C14 Laves phase) and ferrite in agreement with predictions. Both Tc and Re resided predominantly in the Laves phase. In the Fe-Mo-Zr system, the phases included hexagonal C14 with the composition (Fe,Cr)2Mo, cubic C15 phase with a (Fe,Ni)2Zr composition, and the hcp phase Pd2Zr.

  5. ALCHEMI of NbCr{sub 2}/V C15-structured Laves phase

    SciTech Connect

    Kotula, P.G.; Chu, F.; Mitchell, T.E.; Anderson, I.M.; Bentley, J.

    1996-05-01

    Laves-phase intermetallics are of potential interest for use as high temperature structural materials, of which NbCr{sub 2}-based C15- structured Laves phases are particularly attractive. Vanadium-alloyed NbCr{sub 2} Laves phases have been studies. The defect mechanism of a ternary Laves phase is crucial to understanding its physical metallurgy and deformation behavior. It is suggested based on the Nb- Cr-V phase diagram and first-principles total energy and electronic structure calculations for NbCr{sub 2} that V should occupy the B sites in C15-structured AB{sub 2}. In this paper, ALCHEMI is employed to examine this assumption for one composition of a V- alloyed NbCr{sub 2} C15 Laves phase. A Nb-Cr-V alloy of composition Nb{sub 33}Cr{sub 42}V{sub 25} was prepared by arc-melting followed by annealing at 1400{degrees}C for 120 h. Specimens were prepared for microanalysis by cutting 3 mm discs followed by dimpling and ion milling. Energy-dispersive X-ray (EDX) spectra were acquired with a Philips CM30 operating at 300 kV and equipped with a Kevex Quantum detector. Fourteen spectra were collected near <014> over a range of [400] excitations between symmetry and beyond [12 0 0]. Owing to the high accelerating voltage (and therefore relatively flat Ewald sphere) used for these experiments, it was difficult to eliminate non- systematic reflections, although attempts were made to minimize this effect. Spectra were also acquired with a Philips CM12 operating at 120 kV and equipped with an EDAX superUTW detector. Nine spectra were collected near <334> over a range of [440] excitations between symmetry and [880]. Site-distributions were extracted from the data by multivariate statistical analysis (MSA) with delocalization correction as described elsewhere.

  6. Defects and site occupancies in Nb-Cr-Ti C15 Laves phase alloys

    SciTech Connect

    Kotula, P.G.; Carter, C.B.; Chen, K.C.; Thoma, D.J.; Chu, F.; Mitchell, T.E.

    1998-09-01

    A multiply-faulted dipole in the C15 Laves phase of composition Nb{sub 15}Cr{sub 68}Ti{sub 17} has been characterized. The dislocations all lie along [011] and show no residual contrast when imaged edge-on at B = [0{bar 1}{bar 1}] indicating that they are edge in character. Given this, the Burgers vectors for the Shockley partials are {+-} 1/6[2{bar 1}1] and those of the stair-rods are {+-} 1/6[0{bar 1}1]. This is consistent with a g {center_dot} b analysis which was performed. The stacking fault energy was determined to be 35 mJ/m{sup 2} which is higher than the experimental value of 25 mJ/m{sup 2} from NbCr{sub 2}. Simulations are currently underway to understand, given the site occupancies and observed trend in stacking fault energy, whether Ti would be expected to raise the stacking fault energy of the C15 Laves phase.

  7. Formation of prismatic loops from C15 Laves phase interstitial clusters in body-centered cubic iron

    SciTech Connect

    Zhang, Yongfeng; Bai, Xian-Ming; Tonks, Michael R.; Biner, S. Bulent

    2015-03-01

    This Letter reports the transition of C15 phase self-interstitial clusters to loops in body-centered-cubic Iron. Molecular dynamics simulations are performed to evaluate the relative stabilities of difference interstitial cluster configurations including C15 phase structure and <100> and <111>/2 loops. Within a certain size range, C15 cluster are found more stable than loops, and the relative stabilities are reversed beyond that range. In accordance to the crossover in relative stabilities, C15 clusters may grow by absorbing individual interstitials at small sizes and transitions into loops eventually. The transition takes place by nucleation and reaction of <111>/2 loop segments. These observations explain the absence of C15 phase interstitial clusters predicted by density-functional-theory calculations in previous experimental observations. More importantly, the current results provide a new formation mechanism of <100> loops which requires no interaction of loops.

  8. Elastic constants of a Laves phase compound: C15 NbCr{sub 2}

    SciTech Connect

    Ormeci, A. |; Chu, F.; Wills, J.M.; Chen, S.P.; Albers, R.C.; Thoma, D.J.; Mitchell, T.E.

    1997-04-01

    The single-crystal elastic constants of C15 NbCr{sub 2} have been computed by using a first-principles, self-consistent, full-potential total energy method. From these single-crystal elastic constants the isotropic elastic moduli are calculated using the Voigt and Reuss averages. The calculated values are in fair agreement with the experimental values. The implications of the results are discussed with regards to Poisson`s ratio and the direction dependence of Young`s modulus.

  9. Comparison of NbCr{sub 2} and HfV{sub 2} C15 Laves phases

    SciTech Connect

    Thoma, D.J.; Chu, F.; Wills, J.M.; Mitchell, T.E.

    1997-12-31

    The elastic properties, phase stability, and alloying behavior of NbCr{sub 2} and HfV{sub 2} C15 Laves phases have been investigated with a combined experimental and theoretical approach. Experimental results indicate that HfV{sub 2} has anomalous elastic properties as well as a structural instability, but NbCr{sub 2} does not. In addition, ternary phase fields of NbCr{sub 2} with V and HfV{sub 2} with Nb were examined experimentally, and they have substantially different alloying behavior. In order to understand these experimental phenomena, the total energy and electronic structure of C15 NbCr{sub 2} and HfV{sub 2} were calculated using the linear muffin-tin orbital method with the atomic sphere approximation. Calculation results suggest that the phase instability of HfV{sub 2} is induced by phonon softening, and the anomalous elastic properties of HfV{sub 2} appear to be attributed to a doubly degenerate electronic energy level with a linear dispersion relation very close to the Fermi level. Finally, density of states plots indicate that for HfV{sub 2}, some bonding d-states are unoccupied while for NbCr{sub 2}, all bonding and some anti-bonding d-states are occupied. The bonding difference may be responsible for the alloying behavior in the two Laves phase alloys. As a result, alloy design schemes are suggested for enhanced deformability in Laves phases.

  10. Irradiation-induced formation of nano-crystallites with C15 Laves phase structure in bcc iron

    NASA Astrophysics Data System (ADS)

    Marinica, Mihai-Cosmin; Willaime, François; Crocombette, Jean-Paul

    2013-03-01

    The thermal diffusion of defects as vacancies or interstitials is the main process which drives the material towards equilibrium after or in parallel to the damage production. A three dimensional periodic structure is proposed for self-interstitial clusters in body-centered-cubic metals, as opposed to the conventional two dimensional loop morphology. The underlying crystal structure corresponds to the C15 Laves phase. The new three dimensional structures generalize previous observations. By systematic exploration of the energy landscape performed using an Eigenvector Following method and Density Functional Theory calculations, we demonstrate that in α-iron these C15 aggregates are highly stable and immobile and that they exhibit large antiferromagnetic moments. These clusters form directly in displacement cascades and they can grow by capturing self-interstitials. This new morphology of self-interstitial clusters thus constitutes an important element to account for when predicting the microstructural evolution of iron base materials under irradiation.

  11. Synthesis of hexagonal C14/C36 and cubic C15 ZrCr2 Laves phases and thermodynamic stability of their hydrides

    NASA Astrophysics Data System (ADS)

    Bodega, J.; Fernández, J. F.; Leardini, F.; Ares, J. R.; Sánchez, C.

    2011-11-01

    ZrCr2 samples with well defined hexagonal (C14/C36) or cubic (C15) Laves phase structures have been synthesised by melting in an arc furnace followed by different treatments depending on the sample type. Hydrogen absorption capacity and thermodynamic stability of their respective hydrides have been investigated by solid-gas reaction. Pressure-composition-temperature (PCT) curves obtained for both structures at temperatures of 348, 373, 398 and 423 K, and H-pressures from 101 to 106 Pa, showed that the cubic phase is less stable than the hexagonal ones. This result was related to Miedema's rule of reversed stability and also correlated to the volume of the interstitial hole for hydrogen.

  12. Enhancement of a cyclic endurance of phase change memory by application of a high-density C15(Ge21Sb36Te43) film

    NASA Astrophysics Data System (ADS)

    Park, J. H.; Kim, S. W.; Kim, J. H.; Ko, D. H.; Wu, Z.; Ahn, D.; Ahn, D. H.; Lee, J. M.; Kang, S. B.; Choi, S. Y.

    2016-02-01

    The lower cyclic endurance of Phase Change Memory (PCM) devices limits the spread of its applications for reliable memory. The findings reported here show that micro-voids and excess vacancies that are produced during the deposition process and the subsequent growth in sputtered carbon-doped GeSbTe films is one of the major causes of device failure in PCM with cycling. We found that the size of voids in C15(Ge21Sb36Te43) films increased with increasing annealing temperature and the activation energy for the growth rate of voids was determined to be 2.22 eV. The film density, which is closely related to voids, varies with the deposition temperature and sputtering power used. The lower heat of vaporization of elemental Sb and Te compared to that for elemental Ge and C is a major cause of the low density of the film. It was possible to suppress void formation to a considerable extent by optimizing the deposition conditions, which leads to a dramatic enhancement in cyclic endurance by 2 orders of magnitude in PCM devices prepared at 300oC-300W compared to one prepared at 240oC-500W without change of compositions.

  13. 42 CFR 68c.15 - Additional conditions.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 42 Public Health 1 2011-10-01 2011-10-01 false Additional conditions. 68c.15 Section 68c.15 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES FELLOWSHIPS, INTERNSHIPS, TRAINING NATIONAL INSTITUTE OF CHILD HEALTH AND HUMAN DEVELOPMENT CONTRACEPTION AND INFERTILITY RESEARCH...

  14. 42 CFR 68c.15 - Additional conditions.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 42 Public Health 1 2012-10-01 2012-10-01 false Additional conditions. 68c.15 Section 68c.15 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES FELLOWSHIPS, INTERNSHIPS, TRAINING NATIONAL INSTITUTE OF CHILD HEALTH AND HUMAN DEVELOPMENT CONTRACEPTION AND INFERTILITY RESEARCH...

  15. 42 CFR 68c.15 - Additional conditions.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false Additional conditions. 68c.15 Section 68c.15 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES FELLOWSHIPS, INTERNSHIPS, TRAINING NATIONAL INSTITUTE OF CHILD HEALTH AND HUMAN DEVELOPMENT CONTRACEPTION AND INFERTILITY RESEARCH...

  16. ALCHEMI of niobium dichrome/vanadium C15 Laves phase

    SciTech Connect

    Kotula, P.G.; Chu, Fuming; Mitchell, T.E.; Anderson, I.M.; Bentley, J.

    1996-05-01

    33Nb42Cr25V was prepared by arc melting and annealing at 1400 C for 120 hr. Energy-dispersive x-ray spectra were collected over a range of {l_brace}400{l_brace} excitations between symmetry and beyond {l_brace}12 0 0{l_brace}. Results show that at least qualitatively V substitutes for Cr. Therefore, electronic effects must be more important than size effects in this case.

  17. Measuring (13)C/(15)N chemical shift anisotropy in [(13)C,(15)N] uniformly enriched proteins using CSA amplification.

    PubMed

    Hung, Ivan; Ge, Yuwei; Liu, Xiaoli; Liu, Mali; Li, Conggang; Gan, Zhehong

    2015-11-01

    Extended chemical shift anisotropy amplification (xCSA) is applied for measuring (13)C/(15)N chemical shift anisotropy (CSA) of uniformly labeled proteins under magic-angle spinning (MAS). The amplification sequence consists of a sequence of π-pulses that repetitively interrupt MAS averaging of the CSA interaction. The timing of the pulses is designed to generate amplified spinning sideband manifolds which can be fitted to extract CSA parameters. The (13)C/(13)C homonuclear dipolar interactions are not affected by the π-pulses due to the bilinear nature of the spin operators and are averaged by MAS in the xCSA experiment. These features make the constant evolution-time experiment suitable for measuring CSA of uniformly labeled samples. The incorporation of xCSA with multi-dimensional (13)C/(15)N correlation is demonstrated with a GB1 protein sample as a model system for measuring (13)C/(15)N CSA of all backbone (15)NH, (13)CA and (13)CO sites. PMID:26404770

  18. 40 CFR 721.6505 - Polymers of C13C15 oxoalcohol ethoxolates.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Polymers of C13C15 oxoalcohol... Specific Chemical Substances § 721.6505 Polymers of C13C15 oxoalcohol ethoxolates. (a) Chemical substance... polymers of C13C15 oxoalcohol ethoxolates (PMNs P-96-950/951) are subject to reporting under this...

  19. 40 CFR 721.6505 - Polymers of C13C15 oxoalcohol ethoxolates.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Polymers of C13C15 oxoalcohol... Specific Chemical Substances § 721.6505 Polymers of C13C15 oxoalcohol ethoxolates. (a) Chemical substance... polymers of C13C15 oxoalcohol ethoxolates (PMNs P-96-950/951) are subject to reporting under this...

  20. 40 CFR 721.6505 - Polymers of C13C15 oxoalcohol ethoxolates.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Polymers of C13C15 oxoalcohol... Specific Chemical Substances § 721.6505 Polymers of C13C15 oxoalcohol ethoxolates. (a) Chemical substance... polymers of C13C15 oxoalcohol ethoxolates (PMNs P-96-950/951) are subject to reporting under this...

  1. 40 CFR 721.6505 - Polymers of C13C15 oxoalcohol ethoxolates.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Polymers of C13C15 oxoalcohol... Specific Chemical Substances § 721.6505 Polymers of C13C15 oxoalcohol ethoxolates. (a) Chemical substance... polymers of C13C15 oxoalcohol ethoxolates (PMNs P-96-950/951) are subject to reporting under this...

  2. 40 CFR 721.6505 - Polymers of C13C15 oxoalcohol ethoxolates.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Polymers of C13C15 oxoalcohol... Specific Chemical Substances § 721.6505 Polymers of C13C15 oxoalcohol ethoxolates. (a) Chemical substance... polymers of C13C15 oxoalcohol ethoxolates (PMNs P-96-950/951) are subject to reporting under this...

  3. Thermal and electron microprobe analyses of an Ni-0.5C-15Cr-3.2Si-2B alloy

    NASA Astrophysics Data System (ADS)

    Il'inykh, A. S.; Zamyatin, V. M.; Barbin, N. M.

    2014-02-01

    The melting and solidification of a powder alloy Ni-0.5 wt % C-15 wt % Cr-3.2 wt % Si-2 wt % B is studied. The microstructure and chemical composition of the phases present in the compact alloy prepared by melting of the powder are investigated. The sequence of phase formation during solidification of the alloy is suggested.

  4. C15H10 and C15H12 Thermal Chemistry: Phenanthrylcarbene Isomers and Phenylindenes by Falling Solid Flash Vacuum Pyrolysis of Tetrazoles.

    PubMed

    Wentrup, Curt; Becker, Jürgen; Diehl, Manfred

    2015-07-17

    2-Phenyl-5-(phenylethynyl)tetrazole 44 provides a new entry to the C15H10 energy surface. Flash vacuum pyrolysis of 44 using the falling solid flash vacuum pyrolysis (FS-FVP) method afforded cyclopenta[def]phenanthrene 31 and cyclopenta[jk]fluorene 52 as the principal products. The products are explained in terms of the formation of N-phenyl-C-phenylethynylnitrile imine/(phenylazo)(phenylethynyl)carbene 45 and its cyclization to 3-(phenylethynyl)-3H-indazole 46b. Pyrolytic loss of N2 from 46b generates C15H10 intermediate 48. Cyclization of 48 to a dibenzocycloheptatetraene derivative and further rearrangements with analogies in the chemistry of phenylcarbene and the naphthylcarbenes leads to the final products. Similar pyrolysis of 2-phenyl-5-styryltetrazole 43 afforded 3-styrylindazole 58, which on further pyrolysis eliminated N2 to generate 3- and 2-phenylindenes 61 and 62 via C15H12 intermediates. PMID:26086716

  5. Improved mass analysis of oligoribonucleotides by 13C, 15N double depletion and electrospray ionization FT-ICR mass spectrometry.

    PubMed

    Xiong, Ying; Schroeder, Kersten; Greenbaum, Nancy L; Hendrickson, Christopher L; Marshall, Alan G

    2004-03-15

    13C, 15N doubly depleted 32-ribonucleotide was synthesized enzymatically by in vitro transcription from nucleoside triphosphates isolated from E. coli grown in a minimal medium containing 12C, 14N-enriched glucose and ammonium sulfate. Following purification and desalting by reversed-phase HPLC, buffer exchange with Microcon YM-3, and ethanol precipitation, electrospray ionization Fourier transform ion cyclotron resonance mass spectra revealed greatly enhanced abundance of monoisotopic ions (by a factor of approximately 100) and a narrower isotopic distribution with higher signal-to-noise ratio. The abrupt onset and high magnitude of the monoisotopic species promise to facilitate accurate mass measurement of RNA's. PMID:15018587

  6. The First in Vivo Observation of 13C- 15N Coupling in Mammalian Brain

    NASA Astrophysics Data System (ADS)

    Kanamori, Keiko; Ross, Brian D.

    2001-12-01

    [5-13C,15N]Glutamine, with 1J(13C-15N) of 16 Hz, was observed in vivo in the brain of spontaneously breathing rats by 13C MRS at 4.7 T. The brain [5-13C]glutamine peak consisted of the doublet from [5-13C,15N]glutamine and the center [5-13C,14N]glutamine peak, resulting in an apparent triplet with a separation of 8 Hz. The time course of formation of brain [5-13C,15N]glutamine was monitored in vivo with a time resolution of 20-35 min. This [5-13C,15N]glutamine was formed by glial uptake of released neurotransmitter [5-13C]glutamate and its reaction with 15NH3 catalyzed by the glia-specific glutamine synthetase. The neurotransmitter glutamate C5 was selectively13C-enriched by intravenous [2,5-13C]glucose infusion to 13C-label whole-brain glutamate C5, followed by [12C]glucose infusion to chase 13C from the small and rapidly turning-over glial glutamate pool, leaving 13C mainly in the neurotransmitter [5-13C]glutamate pool, which is sequestered in vesicles until release. Hence, the observed [5-13C,15N]glutamine arises from a coupling between 13C of neuronal origin and 15N of glial origin. Measurement of the rate of brain [5-13C,15N]glutamine formation provides a novel noninvasive method of studying the kinetics of neurotransmitter uptake into glia in vivo, a process that is crucial for protecting the brain from glutamate excitotoxicity.

  7. Antifungal effects of synthetic human β-defensin 3-C15 peptide

    PubMed Central

    Ahn, Ki-Bum; Kim, Christine; Kum, Jong-Won; Gu, Yu; Han, Seung Hyun; Shon, Won-Jun; Lee, Woocheol; Zhu, Qiang

    2016-01-01

    Objectives The purpose of this ex vivo study was to compare the antifungal activity of a synthetic peptide consisting of 15 amino acids at the C-terminus of human β-defensin 3 (HBD3-C15) with calcium hydroxide (CH) and Nystatin (Nys) against Candida albicans (C. albicans) biofilm. Materials and Methods C. albicans were grown on cover glass bottom dishes or human dentin disks for 48 hr, and then treated with HBD3-C15 (0, 12.5, 25, 50, 100, 150, 200, and 300 µg/mL), CH (100 µg/mL), and Nys (20 µg/mL) for 7 days at 37℃. On cover glass, live and dead cells in the biomass were measured by the FilmTracer Biofilm viability assay, and observed by confocal laser scanning microscopy (CLSM). On dentin, normal, diminished and ruptured cells were observed by field-emission scanning electron microscopy (FE-SEM). The results were subjected to a two-tailed t-test, a one way analysis variance and a post hoc test at a significance level of p = 0.05. Results C. albicans survival on dentin was inhibited by HBD3-C15 in a dose-dependent manner. There were fewer aggregations of C. albicans in the groups of Nys and HBD3-C15 (≥ 100 µg/mL). CLSM showed C. albicans survival was reduced by HBD3-C15 in a dose dependent manner. Nys and HBD3-C15 (≥ 100 µg/mL) showed significant fungicidal activity compared to CH group (p < 0.05). Conclusions Synthetic HBD3-C15 peptide (≥ 100 µg/mL) and Nys exhibited significantly higher antifungal activity than CH against C. albicans by inhibiting cell survival and biofilm. PMID:27200276

  8. 26 CFR 1.501(c)(15)-1 - Mutual insurance companies or associations.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 26 Internal Revenue 7 2011-04-01 2009-04-01 true Mutual insurance companies or associations. 1.501... Mutual insurance companies or associations. (a) Taxable years beginning after December 31, 1962. An insurance company or association described in section 501(c)(15) is exempt under section 501(a) if it is...

  9. Two-photon excitation of chlorin-e6-C15 monomethyl ester for photodynamic therapy

    NASA Astrophysics Data System (ADS)

    Chen, Ping; Zhao, P. D.; Guo, P.; Lin, Lie; Liu, J. Wei; Yu, Q.

    2005-01-01

    Two-photon-induced fluorescence spectrum and lifetime of Chlorin-e6-C15 Monomethyl Ester in tetrahydrofura (THF) are experimentally examined with femtosecond laser pulses at 800 nm from a Ti:sapphire laser. The two-photon excited fluorescence spectra of the molecule are basically similar to those obtained by one-photon excitation. The lifetimes of two-photon and one-photon excitation fluorescence of this molecule in the solution are of the order of 5.2 ns and 4.8 ns respectively. Our experimental results indicate that the two-photon-induced photodynamic processes of Chlorin-e6-C15 Monomethyl Ester are similar to one-photon-induced photodynamic processes. The two-photon absorption cross section of the molecule is measured at 800 nm as about σ2' ~ 29.1 x 10-50 cm4 " s/photon. As an example for two-photon photodynamic therapy, we also further examine the cell-damaging effects of the Ester. Our preliminary results of cell viability test indicate that Chlorin-e6-C15 Monomethyl Ester can effectively damage the liver cancer cells BEL-7402 under two-photon irradiation. Our results suggest Chlorin-e6-C15 Monomethyl Ester may become a potential two-photon phototherapeutic agent.

  10. 26 CFR 1.501(c)(15)-1 - Mutual insurance companies or associations.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... insurance company or association described in section 501(c)(15) is exempt under section 501(a) if it is a mutual company or association (other than life or marine) or if it is a mutual interinsurer or reciprocal... in § 1.61-7. Interest shall be adjusted for amortization of premium and accrual of discount...

  11. 26 CFR 1.381(c)(15)-1 - Indebtedness of certain personal holding companies.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 26 Internal Revenue 4 2010-04-01 2010-04-01 false Indebtedness of certain personal holding...)-1 Indebtedness of certain personal holding companies. (a) Qualified indebtedness—(1) Carryover... indebtedness, then, under section 381(c)(15), in computing its undistributed personal holding company...

  12. 26 CFR 1.381(c)(15)-1 - Indebtedness of certain personal holding companies.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 26 Internal Revenue 4 2011-04-01 2011-04-01 false Indebtedness of certain personal holding...)-1 Indebtedness of certain personal holding companies. (a) Qualified indebtedness—(1) Carryover... indebtedness, then, under section 381(c)(15), in computing its undistributed personal holding company...

  13. Synthesis of C-15 Vindoline Analogues by Palladium-Catalyzed Cross-Coupling Reactions

    PubMed Central

    Johnson, Peter D.; Sohn, Jeong-Hun

    2008-01-01

    Described are general protocols for the rapid construction of various C-15-substituted analogs of vindoline using palladium-catalyzed cross-coupling reactions. The required bromo- and iodovindolines were prepared in high yield by the reaction of vindoline with N-bromosuccinimide or N-iodosuccinimide, respectively. The study not only led to the synthesis a number of structurally novel vindoline analogues but also opens the door to new strategies for the synthesis of vinblastine, vincristine, and related anticancer agents. Also described is the conversion of ent-tabersonine to ent-vindoline. PMID:16995709

  14. 26 CFR 31.3306(c)(15)-1 - Services in delivery or distribution of newspapers, shopping news, or magazines.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... newspapers, shopping news, or magazines. 31.3306(c)(15)-1 Section 31.3306(c)(15)-1 Internal Revenue INTERNAL..., shopping news, or magazines. (a) Services of individuals under age 18. Services performed by an employee under the age of 18 in the delivery or distribution of newspapers or shopping news, not...

  15. 26 CFR 31.3306(c)(15)-1 - Services in delivery or distribution of newspapers, shopping news, or magazines.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... newspapers, shopping news, or magazines. 31.3306(c)(15)-1 Section 31.3306(c)(15)-1 Internal Revenue INTERNAL..., shopping news, or magazines. (a) Services of individuals under age 18. Services performed by an employee under the age of 18 in the delivery or distribution of newspapers or shopping news, not...

  16. 26 CFR 31.3306(c)(15)-1 - Services in delivery or distribution of newspapers, shopping news, or magazines.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... newspapers, shopping news, or magazines. 31.3306(c)(15)-1 Section 31.3306(c)(15)-1 Internal Revenue INTERNAL..., shopping news, or magazines. (a) Services of individuals under age 18. Services performed by an employee under the age of 18 in the delivery or distribution of newspapers or shopping news, not...

  17. 26 CFR 31.3306(c)(15)-1 - Services in delivery or distribution of newspapers, shopping news, or magazines.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... newspapers, shopping news, or magazines. 31.3306(c)(15)-1 Section 31.3306(c)(15)-1 Internal Revenue INTERNAL..., shopping news, or magazines. (a) Services of individuals under age 18. Services performed by an employee under the age of 18 in the delivery or distribution of newspapers or shopping news, not...

  18. 26 CFR 31.3306(c)(15)-1 - Services in delivery or distribution of newspapers, shopping news, or magazines.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... newspapers, shopping news, or magazines. 31.3306(c)(15)-1 Section 31.3306(c)(15)-1 Internal Revenue INTERNAL..., shopping news, or magazines. (a) Services of individuals under age 18. Services performed by an employee under the age of 18 in the delivery or distribution of newspapers or shopping news, not...

  19. Correlation between hereditary structures and properties of an Fe50Cr15Mo14C15B6 bulk-amorphous alloy in the solid and liquid states

    NASA Astrophysics Data System (ADS)

    Filippov, K. S.

    2010-05-01

    An attempt is made to find the effect of a hereditary structure on the physicochemical and structural properties of a solid and liquid Fe50Cr15Mo14C15B6 bulk-amorphous alloy in order to evaluate the possibility of using a precursor, i.e., a solid metal that has a genetic relation to the liquid phase, as an the initial metal of a heat involved in the formation of an amorphous structure. The structural state of the melt is estimated from the temperature dependence of the structural parameters, density, and surface tension with allowance for the validation criterion of the approximation of experimental points R 2.

  20. BnC15 and BnATA20, the different putative components, control anther development in Brassica napus L.

    PubMed

    Wan, Lili; Hu, Qin; Hong, Dengfeng; Yang, Guangsheng

    2012-10-01

    In Brassica napus, male fertility depends on proper cell differentiation in the anther. However, relatively little is known about the genes regulating anther cell differentiation and function. Here, we report two floral organ specific genes, BnC15 and BnATA20, derived from a B. napus two-line Rs1046A/B floral subtractive library. Although BnC15 and BnATA20 genes have a different expression pattern in anthers demonstrated by in situ hybridization and real-time PCR analysis, silencing of both genes in B. napus by antisense suppression resulted in pollen abortion after microspore release. Light and electron microscopy observation revealed the lack of plastoglobuli, lipid bodies and sporopollenin secreted from the tapetum leading to aberrations in exine sculpturing and the formation of a pollen coat. In addition, the microspores were squeezed to the irregular shape in the locule in the end. As shown by gene expression analysis in transgenic plants and the comparison of anther development between bnc15 or bnata20 mutants and Rs1046A, BnC15 and BnATA20 were positively regulated downstream of Rf gene controlling the fertility of Rs1046B in the same pathway. The results support the hypothesis that BnC15 and BnATA20 are crucial components of a genetic network that controls tapetum development and exine sculpturing. PMID:22841791

  1. Application of unsymmetrical indirect covariance NMR methods to the computation of the (13)C <--> (15)N HSQC-IMPEACH and (13)C <--> (15)N HMBC-IMPEACH correlation spectra.

    PubMed

    Martin, Gary E; Hilton, Bruce D; Irish, Patrick A; Blinov, Kirill A; Williams, Antony J

    2007-10-01

    Utilization of long-range (1)H--(15)N heteronuclear chemical shift correlation has continually grown in importance since the first applications were reported in 1995. More recently, indirect covariance NMR methods have been introduced followed by the development of unsymmetrical indirect covariance processing methods. The latter technique has been shown to allow the calculation of hyphenated 2D NMR data matrices from more readily acquired nonhyphenated 2D NMR spectra. We recently reported the use of unsymmetrical indirect covariance processing to combine (1)H--(13)C GHSQC and (1)H--(15)N GHMBC long-range spectra to yield a (13)C--(15)N HSQC-HMBC chemical shift correlation spectrum that could not be acquired in a reasonable period of time without resorting to (15)N-labeled molecules. We now report the unsymmetrical indirect covariance processing of (1)H--(13)C GHMBC and (1)H--(15)N IMPEACH spectra to afford a (13)C--(15)N HMBC-IMPEACH spectrum that has the potential to span as many as six to eight bonds. Correlations for carbon resonances long-range coupled to a protonated carbon in the (1)H--(13)C HMBC spectrum are transferred via the long-range (1)H--(15)N coupling pathway in the (1)H--(15)N IMPEACH spectrum to afford a much broader range of correlation possibilities in the (13)C--(15)N HMBC-IMPEACH correlation spectrum. The indole alkaloid vincamine is used as a model compound to illustrate the application of the method. PMID:17729230

  2. Simple shearing flow of dry soap foams with TCP structure[Tetrahedrally Close-Packed

    SciTech Connect

    REINELT,DOUGLAS A.; KRAYNIK,ANDREW M.

    2000-02-16

    The microrheology of dry soap foams subjected to large, quasistatic, simple shearing deformations is analyzed. Two different monodisperse foams with tetrahedrally close-packed (TCP) structure are examined: Weaire-Phelan (A15) and Friauf-Laves (C15). The elastic-plastic response is evaluated by calculating foam structures that minimize total surface area at each value of strain. The minimal surfaces are computed with the Surface Evolver program developed by Brakke. The foam geometry and macroscopic stress are piecewise continuous functions of strain. The stress scales as T/V{sup 1/3} where T is surface tension and V is cell volume. Each discontinuity corresponds to large changes in foam geometry and topology that restore equilibrium to unstable configurations that violate Plateau's laws. The instabilities occur when the length of an edge on a polyhedral foam cell vanishes. The length can tend to zero smoothly or abruptly with strain. The abrupt case occurs when a small increase in strain changes the energy profile in the neighborhood of a foam structure from a local minimum to a saddle point, which can lead to symmetry-breaking bifurcations. In general, the new foam topology associated with each stable solution branch results from a cascade of local topology changes called T1 transitions. Each T1 cascade produces different cell neighbors, reduces surface energy, and provides an irreversible, film-level mechanism for plastic yield behavior. Stress-strain curves and average stresses are evaluated by examining foam orientations that admit strain-periodic behavior. For some orientations, the deformation cycle includes Kelvin cells instead of the original TCP structure; but the foam does not remain perfectly ordered. Bifurcations during subsequent T1 cascades lead to disorder and can even cause strain localization.

  3. Simple shearing flow of dry soap foams with tetrahedrally close-packed structure

    SciTech Connect

    Reinelt, Douglas A.; Kraynik, Andrew M.

    2000-05-01

    The microrheology of dry soap foams subjected to quasistatic, simple shearing flow is analyzed. Two different monodisperse foams with tetrahedrally close-packed (TCP) structure are examined: Weaire-Phelan (A15) and Friauf-Laves (C15). The elastic-plastic response is evaluated by using the Surface Evolver to calculate foam structures that minimize total surface area at each value of strain. The foam geometry and macroscopic stress are piecewise continuous functions of strain. The stress scales as T/V{sup 1/3}, where T is surface tension and V is cell volume. Each discontinuity corresponds to large changes in foam geometry and topology that restore equilibrium to unstable configurations that violate Plateau's laws. The instabilities occur when the length of an edge on a polyhedral foam cell vanishes. The length can tend to zero smoothly or abruptly with strain. The abrupt case occurs when a small increase in strain changes the energy profile in the neighborhood of a foam structure from a local minimum to a saddle point, which can lead to symmetry-breaking bifurcations. In general, the new structure associated with each stable solution branch results from an avalanche of local topology changes called T1 transitions. Each T1 cascade produces different cell neighbors, reduces surface energy, and provides an irreversible, film-level mechanism for plastic yield behavior. Stress-strain curves and average stresses are evaluated by examining foam orientations that admit strain-periodic behavior. For some orientations, the deformation cycle includes Kelvin cells instead of the original TCP structure; but the foam does not remain perfectly ordered. Bifurcations during subsequent T1 cascades lead to disorder and can even cause strain localization. (c) 2000 Society of Rheology.

  4. Benchmark fragment-based (1)H, (13)C, (15)N and (17)O chemical shift predictions in molecular crystals.

    PubMed

    Hartman, Joshua D; Kudla, Ryan A; Day, Graeme M; Mueller, Leonard J; Beran, Gregory J O

    2016-08-21

    The performance of fragment-based ab initio(1)H, (13)C, (15)N and (17)O chemical shift predictions is assessed against experimental NMR chemical shift data in four benchmark sets of molecular crystals. Employing a variety of commonly used density functionals (PBE0, B3LYP, TPSSh, OPBE, PBE, TPSS), we explore the relative performance of cluster, two-body fragment, and combined cluster/fragment models. The hybrid density functionals (PBE0, B3LYP and TPSSh) generally out-perform their generalized gradient approximation (GGA)-based counterparts. (1)H, (13)C, (15)N, and (17)O isotropic chemical shifts can be predicted with root-mean-square errors of 0.3, 1.5, 4.2, and 9.8 ppm, respectively, using a computationally inexpensive electrostatically embedded two-body PBE0 fragment model. Oxygen chemical shieldings prove particularly sensitive to local many-body effects, and using a combined cluster/fragment model instead of the simple two-body fragment model decreases the root-mean-square errors to 7.6 ppm. These fragment-based model errors compare favorably with GIPAW PBE ones of 0.4, 2.2, 5.4, and 7.2 ppm for the same (1)H, (13)C, (15)N, and (17)O test sets. Using these benchmark calculations, a set of recommended linear regression parameters for mapping between calculated chemical shieldings and observed chemical shifts are provided and their robustness assessed using statistical cross-validation. We demonstrate the utility of these approaches and the reported scaling parameters on applications to 9-tert-butyl anthracene, several histidine co-crystals, benzoic acid and the C-nitrosoarene SnCl2(CH3)2(NODMA)2. PMID:27431490

  5. Simple, efficient protocol for enzymatic synthesis of uniformly 13C, 15N-labeled DNA for heteronuclear NMR studies.

    PubMed Central

    Masse, J E; Bortmann, P; Dieckmann, T; Feigon, J

    1998-01-01

    The use of uniformly 13C,15N-labeled RNA has greatly facilitated structural studies of RNA oligonucleotides by NMR. Application of similar methodologies for the study of DNA has been limited, primarily due to the lack of adequate methods for sample preparation. Methods for both chemical and enzymatic synthesis of DNA oligonucleotides uniformly labeled with 13C and/or 15N have been published, but have not yet been widely used. We have developed a modified procedure for preparing uniformly 13C,15N-labeled DNA based on enzymatic synthesis using Taq DNA polymerase. The highly efficient protocol results in quantitative polymerization of the template and approximately 80% incorporation of the labeled dNTPs. Procedures for avoiding non-templated addition of nucleotides or for their removal are given. The method has been used to synthesize several DNA oligonucleotides, including two complementary 15 base strands, a 32 base DNA oligonucleotide that folds to form an intramolecular triplex and a 12 base oligonucleotide that dimerizes and folds to form a quadruplex. Heteronuclear NMR spectra of the samples illustrate the quality of the labeled DNA obtained by these procedures. PMID:9592146

  6. Biosynthetic uniform 13C,15N-labelling of zervamicin IIB. Complete 13C and 15N NMR assignment.

    PubMed

    Ovchinnikova, Tatyana V; Shenkarev, Zakhar O; Yakimenko, Zoya A; Svishcheva, Natalia V; Tagaev, Andrey A; Skladnev, Dmitry A; Arseniev, Alexander S

    2003-01-01

    Zervamicin IIB is a member of the alpha-aminoisobutyric acid containing peptaibol antibiotics. A new procedure for the biosynthetic preparation of the uniformly 13C- and 15N-enriched peptaibol is described This compound was isolated from the biomass of the fungus-producer Emericellopsis salmosynnemata strain 336 IMI 58330 obtained upon cultivation in the totally 13C, 15N-labelled complete medium. To prepare such a medium the autolysed biomass and the exopolysaccharides of the obligate methylotrophic bacterium Methylobacillus flagellatus KT were used. This microorganism was grown in totally 13C, 15N-labelled minimal medium containing 13C-methanol and 15N-ammonium chloride as the only carbon and nitrogen sources. Preliminary NMR spectroscopic analysis indicated a high extent of isotope incorporation (> 90%) and led to the complete 13C- and 15N-NMR assignment including the stereospecific assignment of Aib residues methyl groups. The observed pattern of the structurally important secondary chemical shifts of 1H(alpha), 13C=O and 13C(alpha) agrees well with the previously determined structure of zervamicin IIB in methanol solution. PMID:14658801

  7. Polyamine flux analysis by determination of heavy isotope incorporation from 13C, 15N-enriched amino acids into polyamines by LC-MS/MS.

    PubMed

    Cerrada-Gimenez, Marc; Häkkinen, Merja R; Vepsäläinen, Jouko; Auriola, Seppo; Alhonen, Leena; Keinänen, Tuomo A

    2012-02-01

    The study of polyamine flux, i.e. the circulating flow of polyamines through the interconnected biosynthetic and catabolic pathways, is of considerable interest because of the established links between the polyamine metabolism and many diseases, such as cancer and diabetes. To study polyamine flux in detail, a novel method based on following the label incorporation from the (13)C, (15)N-labeled polyamine precursors, arginine, methionine and ornithine, into polyamines by LC-MS/MS was implemented. This methodology was tested on three distinct cell lines with different spermidine/spermine-N (1)-acetyltransferase (SSAT) expression levels, i.e. non-transgenic, transgenic and knockout. These trials allowed the identification of the critical conditions for the successful polyamine flux measurement, such as the functional time frame of label incorporation, until plateau phase with the selected precursor is reached. The novel LC-MS/MS-based method for polyamine flux overcame the limitations of previous existing methodologies, with baseline separation of the different polyamine species and the exact quantification of the incorporated label. Moreover, the obtained results clearly show that the increased SSAT expression is associated with accelerated polyamine flux. PMID:21818565

  8. Heterogeneous Diastereoselective Catalysis--A Powerful Strategy Toward C(15) Stereoselectivity from PGF2α Analogues Structure.

    PubMed

    Coman, Simona M; Parvulescu, Vasile I

    2015-01-01

    A major trend in fine chemicals and pharmaceuticals is the synthesis of molecules with increased complexity. This trend translates the aim of organic syntheses to conditions in which high degrees of chemo-, regio- and stereoselectivity can be provided. In this context, the chemoselective hydrogenation of one functional group in the presence of other reactive groups is a frequently encountered problem in fine chemicals manufacture. This study provides a critical analysis including elegant examples of reactions in which high chemo- and diastereoselectivities were achieved in the hydrogenation of a C=O group in the presence of C=C double bond. A particular emphasis is addressed to the stereoselective C(15) synthesis from Cloprostenol--a PGF2α structural analogue. PMID:26553252

  9. Interresidue carbonyl-carbonyl polarization transfer experiments in uniformly 13C, 15N-labeled peptides and proteins

    NASA Astrophysics Data System (ADS)

    Janik, Rafal; Ritz, Emily; Gravelle, Andrew; Shi, Lichi; Peng, Xiaohu; Ladizhansky, Vladimir

    2010-03-01

    In this work, we demonstrate that Homonuclear Rotary Resonance Recoupling (HORROR) can be used to reintroduce carbonyl-carbonyl interresidue dipolar interactions and to achieve efficient polarization transfer between carbonyl atoms in uniformly 13C, 15N-labeled peptides and proteins. We show that the HORROR condition is anisotropically broadened and overall shifted to higher radio frequency intensities because of the CSA effects. These effects are analyzed theoretically using Average Hamiltonian Theory. At spinning frequencies used in this study, 22 kHz, this broadening is experimentally found to be on the order of a kilohertz at a proton field of 600 MHz. To match HORROR condition over all powder orientations, variable amplitude radio frequency (RF) fields are required, and efficient direct transfers on the order of 20-30% can be straightforwardly established. Two- and three-dimensional chemical shift correlation experiments establishing long-range interresidue connectivities (e.g., (N[i]-CO[i - 2])) are demonstrated on the model peptide N-acetyl-valine-leucine, and on the third immunoglobulin binding domain of protein G. Possible future developments are discussed.

  10. Interresidue carbonyl-carbonyl polarization transfer experiments in uniformly 13C,15N-labeled peptides and proteins.

    PubMed

    Janik, Rafal; Ritz, Emily; Gravelle, Andrew; Shi, Lichi; Peng, Xiaohu; Ladizhansky, Vladimir

    2010-03-01

    In this work, we demonstrate that Homonuclear Rotary Resonance Recoupling (HORROR) can be used to reintroduce carbonyl-carbonyl interresidue dipolar interactions and to achieve efficient polarization transfer between carbonyl atoms in uniformly (13)C,(15)N-labeled peptides and proteins. We show that the HORROR condition is anisotropically broadened and overall shifted to higher radio frequency intensities because of the CSA effects. These effects are analyzed theoretically using Average Hamiltonian Theory. At spinning frequencies used in this study, 22kHz, this broadening is experimentally found to be on the order of a kilohertz at a proton field of 600MHz. To match HORROR condition over all powder orientations, variable amplitude radio frequency (RF) fields are required, and efficient direct transfers on the order of 20-30% can be straightforwardly established. Two- and three-dimensional chemical shift correlation experiments establishing long-range interresidue connectivities (e.g., (N[i]-CO[i-2])) are demonstrated on the model peptide N-acetyl-valine-leucine, and on the third immunoglobulin binding domain of protein G. Possible future developments are discussed. PMID:20060344

  11. Temperature stabilized phase detector

    NASA Technical Reports Server (NTRS)

    Lo, Y.

    1981-01-01

    The construction, tests, and performance of a temperature stabilized phase detector are discussed. It has a frequency stability of 5 parts in 10 to the 16th power at 100 MHz, with a temperature step of 20 C (15 to 35 C).

  12. Rotational and rovibrational spectrum of C 15NC 15N in the region of the bending modes ν4, ν5, the combination band ν4 + ν5 and the Fermi interacting modes ν3, 2 ν4

    NASA Astrophysics Data System (ADS)

    Seibert, J. W. Günter; Winnewisser, Manfred; Winnewisser, Brenda P.; Bickelhaupt, Friedrich

    1996-02-01

    The high-resolution gas-phase Fourier transform infrared spectrum of the doubly 15N-substituted isocyanogen, C 15NC 15N, has been measured in the spectral regions 160-240 cm -1 and 390-1110 cm -1 with unapodized resolutions of 0.0017 and 0.0021 cm -1 respectively. In these experiments we were able to measure the band systems due to the excitation of the bending modes ν5 and ν4 at 190.9 cm -1 and 458.1 cm -1, a combination band system of the two bending modes ν4 + ν5 at 649.7 cm -1, as well as two band systems arising from a Fermi interaction between the twofold excited bending mode 2 ν4 and the stretching mode ν3 at 869.9 cm -1 and 960.2 cm -1 respectively. Furthermore, we have measured and assigned pure rotational transitions of C 15NC 15N in the vibrational ground state and in excited vibrational bending states lying in the microwave and the millimeter wave region between 19.9 and 20.2 GHz, 29.9 and 30.4 GHz and 120 and 440 GHz. Constants of a power series in J( J + 1) for numerous rovibrational subbands, as well as accurate molecular constants using the effective hamiltonian for linear polyatomic molecules, defined by Yamada et al. [J. Mol. Spectrosc., 112 (1985) 347], were determined.

  13. Quality of Life in Patients With Brain Metastases Using the EORTC QLQ-BN20+2 and QLQ-C15-PAL

    SciTech Connect

    Caissie, Amanda; Nguyen, Janet; Chen, Emily; Zhang Liying; Sahgal, Arjun; Clemons, Mark; Kerba, Marc; Arnalot, Palmira Foro; Danjoux, Cyril; Tsao, May; Barnes, Elizabeth; Holden, Lori; Danielson, Brita; Chow, Edward

    2012-07-15

    Purpose: The 20-item European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire-Brain Neoplasm (QLQ-BN20) is a validated quality-of-life (QOL) questionnaire for patients with primary brain tumors. The European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire-Core 15 Palliative (QLQ-C15-PAL) core palliative questionnaire is a 15-item version of the core 30-item QLQ-C30 and was developed to decrease the burden on patients with advanced cancer. The combination of the QLQ-BN20 and QLQ-C30 to assess QOL may be too burdensome for patients. The primary aim of this study was to assess QOL in patients before and after treatment for brain metastases using the QLQ-BN20+2 and QLQ-C15-PAL, a version of the QLQ-BN20 questionnaire with 2 additional questions assessing cognitive functioning that were not addressed in the QLQ-C15-PAL. Methods and Materials: Patients with brain metastases completed the QLQ-C15-PAL and QLQ-BN20+2 questionnaires to assess QOL before and 1 month after radiation. Linear regression analysis was used to assess changes in QOL scores over time, as well as to explore associations between the QLQ-BN20+2 and QLQ-C15-PAL scales, patient demographics, and clinical variables. Spearman correlation assessed associations between the QLQ-BN20+2 and QLQ-C15-PAL scales. Results: Among 108 patients, the majority (55%) received whole-brain radiotherapy only, with 65% of patients completing follow-up at 1 month after treatment. The most prominent symptoms at baseline were future uncertainty (QLQ-BN20+2) and fatigue (QLQ-C15-PAL). After treatment, significant improvement was seen for the QLQ-C15-PAL insomnia scale, as well as the QLQ-BN20+2 scales of future uncertainty, visual disorder, and concentration difficulty. Baseline Karnofsky Performance Status was negatively correlated to QLQ-BN20+2 motor dysfunction but positively related to QLQ-C15-PAL physical functioning and QLQ-BN20+2 cognitive functioning at

  14. Statistical model structure of A1-xZxB2 Laves phase C15 system—the superconducting alloy Ce1-xLaxRu2

    NASA Astrophysics Data System (ADS)

    Robouch, B. V.; Marcelli, A.; Saini, N. L.; Kisiel, A.

    2009-01-01

    The local structure of the Ce1-xLaxRu2 system measured by EXAFS is re-examined and correlated to the statistical ad hoc model recently applied to the sphalerite, wurtzite, and other intermetallic ternary alloys. Deconvolution of the EXAFS data shows that the Ce1-xLaxRu2 ternary system is essentially a mixture of CeRu2 and LaRu2 binary alloys with a small proportion of the Ce0.5La0.5Ru2 ternary configuration, which is maximum for the intermediate concentration. Moreover, the analysis reveals that while the LaRu2 configuration exhibits a Bernoulli random distribution, the presence of a Ce atom affects both the CeRu2 and Ce0.5La0.5Ru2 distributions, strongly favoring the configuration with the CeCe pair, while keeping rare that with a single Ce ion.

  15. Fermentation and Cost-Effective 13C/15N Labeling of the Nonribosomal Peptide Gramicidin S for Nuclear Magnetic Resonance Structure Analysis.

    PubMed

    Berditsch, Marina; Afonin, Sergii; Steineker, Anna; Orel, Nataliia; Jakovkin, Igor; Weber, Christian; Ulrich, Anne S

    2015-06-01

    Gramicidin S (GS) is a nonribosomally synthesized decapeptide from Aneurinibacillus migulanus. Its pronounced antibiotic activity is attributed to amphiphilic structure and enables GS interaction with bacterial membranes. Despite its medical use for over 70 years, the peptide-lipid interactions of GS and its molecular mechanism of action are still not fully understood. Therefore, a comprehensive structural analysis of isotope-labeled GS needs to be performed in its biologically relevant membrane-bound state, using advanced solid-state nuclear magnetic resonance (NMR) spectroscopy. Here, we describe an efficient method for producing the uniformly (13)C/(15)N-labeled peptide in a minimal medium supplemented by selected amino acids. As GS is an intracellular product of A. migulanus, we characterized the producer strain DSM 5759 (rough-convex phenotype) and examined its biosynthetic activity in terms of absolute and biomass-dependent peptide accumulation. We found that the addition of either arginine or ornithine increases the yield only at very high supplementing concentrations (1% and 0.4%, respectively) of these expensive (13)C/(15)N-labeled amino acids. The most cost-effective production of (13)C/(15)N-GS, giving up to 90 mg per gram of dry cell weight, was achieved in a minimal medium containing 1% (13)C-glycerol and 0.5% (15)N-ammonium sulfate, supplemented with only 0.025% of (13)C/(15)N-phenylalanine. The 100% efficiency of labeling is corroborated by mass spectrometry and preliminary solid-state NMR structure analysis of the labeled peptide in the membrane-bound state. PMID:25795666

  16. Fermentation and Cost-Effective 13C/15N Labeling of the Nonribosomal Peptide Gramicidin S for Nuclear Magnetic Resonance Structure Analysis

    PubMed Central

    Berditsch, Marina; Afonin, Sergii; Steineker, Anna; Orel, Nataliia; Jakovkin, Igor; Weber, Christian

    2015-01-01

    Gramicidin S (GS) is a nonribosomally synthesized decapeptide from Aneurinibacillus migulanus. Its pronounced antibiotic activity is attributed to amphiphilic structure and enables GS interaction with bacterial membranes. Despite its medical use for over 70 years, the peptide-lipid interactions of GS and its molecular mechanism of action are still not fully understood. Therefore, a comprehensive structural analysis of isotope-labeled GS needs to be performed in its biologically relevant membrane-bound state, using advanced solid-state nuclear magnetic resonance (NMR) spectroscopy. Here, we describe an efficient method for producing the uniformly 13C/15N-labeled peptide in a minimal medium supplemented by selected amino acids. As GS is an intracellular product of A. migulanus, we characterized the producer strain DSM 5759 (rough-convex phenotype) and examined its biosynthetic activity in terms of absolute and biomass-dependent peptide accumulation. We found that the addition of either arginine or ornithine increases the yield only at very high supplementing concentrations (1% and 0.4%, respectively) of these expensive 13C/15N-labeled amino acids. The most cost-effective production of 13C/15N-GS, giving up to 90 mg per gram of dry cell weight, was achieved in a minimal medium containing 1% 13C-glycerol and 0.5% 15N-ammonium sulfate, supplemented with only 0.025% of 13C/15N-phenylalanine. The 100% efficiency of labeling is corroborated by mass spectrometry and preliminary solid-state NMR structure analysis of the labeled peptide in the membrane-bound state. PMID:25795666

  17. IUPAC-NIST Solubility Data Series. 91. Phenols with Water. Part 2. C8 to C15 Alkane Phenols with Water

    NASA Astrophysics Data System (ADS)

    Góral, Marian; Shaw, David G.; Måczyński, Andrzej; Wiśniewska-Gocłowska, Barbara

    2011-09-01

    The mutual solubilities and related liquid-liquid equilibria of 43 binary systems of C7 to C15 phenols with water are exhaustively and critically reviewed. Reports of experimental determination of solubility that appeared in the primary literature prior to the end of 2009 are compiled. For 11 systems, sufficient data are available to allow critical evaluation. All data are expressed as mass percent and mole fraction as well as the originally reported units. The standard evaluation criteria used throughout the Solubility Data Series were applied.

  18. 13C/15N‐Enriched l‐Dopa as a Triple‐Resonance NMR Probe to Monitor Neurotransmitter Dopamine in the Brain and Liver Extracts of Mice

    PubMed Central

    Kameda, Tetsuro; Kimura, Yu; Imai, Hirohiko; Matsuda, Tetsuya; Sando, Shinsuke; Toshimitsu, Akio

    2015-01-01

    Abstract In an attempt to monitor μm‐level trace constituents, we applied here 1H‐{13C‐15N} triple‐resonance nuclear magnetic resonance (NMR) to 13C/15N‐enriched l‐Dopa as the inevitable precursor of the neurotransmitter dopamine in the brain. The perfect selectivity (to render endogenous components silent) and μm‐level sensitivity (700 MHz spectrometer equipped with a cryogenic probe) of triple‐resonance allowed the unambiguous and quantitative metabolic and pharmacokinetic analyses of administered l‐Dopa/dopamine in the brain and liver of mice. The level of dopamine generated in the brain (within the range 7–76 μm, which covers the typical stimulated level of ∼30 μm) could be clearly monitored ex vivo, but was slightly short of the detection limit of a 7 T MR machine for small animals. This work suggests that μm‐level trace constituents are potential targets of ex vivo monitoring as long as they contain N atom(s) and their appropriate 13C/15N‐enrichment is synthetically accessible. PMID:27308224

  19. SIMS ion microscopy imaging of boronophenylalanine (BPA) and 13C15N-labeled phenylalanine in human glioblastoma cells: Relevance of subcellular scale observations to BPA-mediated boron neutron capture therapy of cancer

    NASA Astrophysics Data System (ADS)

    Chandra, Subhash; Lorey, Daniel R., II

    2007-02-01

    p-Boronophenylalanine (BPA) is a clinically approved boron neutron capture therapy (BNCT) agent currently being used in clinical trials of glioblastoma multiforme, melanoma and liver metastases. Secondary ion mass spectrometry (SIMS) observations from the Cornell SIMS Laboratory provided support for using a 6 h infusion of BPA, instead of a 2 h infusion, for achieving higher levels of boron in brain tumor cells. These observations were clinically implemented in Phase II experimental trials of glioblastoma multiforme in Sweden. However, the mechanisms for higher BPA accumulation with longer infusions have remained unknown. In this work, by using 13C15N-labeled phenylalanine and T98G human glioblastoma cells, comparisons between the 10B-delivery of BPA and the accumulation of labeled phenylalanine after 2 and 6 h treatments were made with a Cameca IMS-3f SIMS ion microscope at 500 nm spatial resolution in fast frozen, freeze-fractured, freeze-dried cells. Due to the presence of the Na-K-ATPase in the plasma membrane of most mammalian cells, the cells maintain an approximately 10/1 ratio of K/Na in the intracellular milieu. Therefore, the quantitative imaging of these highly diffusible species in the identical cell in which the boron or labeled amino acid was imaged provides a rule-of-thumb criterion for validation of SIMS observations and the reliability of the cryogenic sampling. The labeled phenylalanine was detected at mass 28, as the 28(13C15N)- molecular ion. Correlative analysis with optical and confocal laser scanning microscopy revealed that fractured freeze-dried glioblastoma cells contained well-preserved ultrastructural details with three discernible subcellular regions: a nucleus or multiple nuclei, a mitochondria-rich perinuclear cytoplasmic region and the remaining cytoplasm. SIMS analysis revealed that the overall cellular signals of both 10B from BPA and 28CN- from labeled phenylalanine increased approximately 1.6-fold between the 2 and 6 h exposures

  20. HCN, a triple-resonance NMR technique for selective observation of histidine and tryptophan side chains in 13C/15N-labeled proteins.

    PubMed

    Sudmeier, J L; Ash, E L; Günther, U L; Luo, X; Bullock, P A; Bachovchin, W W

    1996-12-01

    HCN, a new 3D NMR technique for stepwise coherence transfer from 1H to 13C to 15N and reverse through direct spin couplings 1JCH and 1JCN, is presented as a method for detection and assignment of histidine and tryptophan side-chain 1H, 13C, and 15N resonances in uniformly 13C/15N-labeled proteins. Product-operator calculations of cross-peak volumes vs adjustable delay tau 3 were employed for determination of optimal tau 3. For the phosphatidylinositol 3-kinase (PI3K SH3 domain, MW = 9.6 kD) at pH 6, H(C)N, the 1H/15N projection, produced observable cross peaks within 20 min. and was completely selective for the single tryptophan and single histidine. The 3D HCN experiment yielded well-defined cross peaks in 20 h for the 13C/15N-labeled origin-specific DNA binding domain from simian virus 40 T-antigen (T-ag-OBD131-259, MW = 15.4 kD) at pH 5.5. Resonances from all six histidines in T-ag-OBD were observed, and 11 of the 12 1H and 13C chemical shifts and 10 of the 12 15N chemical shifts were determined. The 13C dimension proved essential in assignment of the multiply overlapping 1H and 15N resonances. From the spectra recorded at a single pH, three of the imidazoles were essentially neutral and the other three were partially protonated (22-37%). HCN yielded strong cross peaks after 18 h on a 2.0 mM sample of phenylmethanesulfonyl fluoride (PMSF)-inhibited alpha-lytic protease (MW = 19.8 kD) at pH 4.4. No spectra have been obtained, however, of native or boronic acid-inhibited alpha-lytic protease after 18 h at various temperatures ranging from 5 to 55 degrees C, probably due to efficient relaxation of active-site imidazole 1H and/or 15N nuclei. PMID:8995843

  1. HCN, A Triple-Resonance NMR Technique for Selective Observation of Histidine and Tryptophan Side Chains in 13C/ 15N-Labeled Proteins

    NASA Astrophysics Data System (ADS)

    Sudmeier, James L.; Ash, Elissa L.; Günther, Ulrich L.; Luo, Xuelian; Bullock, Peter A.; Bachovchin, William W.

    1996-12-01

    HCN, a new 3D NMR technique for stepwise coherence transfer from1H to13C to15N and reverse through direct spin couplings1JCHand1JCN, is presented as a method for detection and assignment of histidine and tryptophan side-chain1H,13C, and15N resonances in uniformly13C/15N-labeled proteins. Product-operator calculations of cross-peak volumes vs adjustable delay τ3were employed for determination of optimal τ3. For the phosphatidylinositol 3-kinase (PI3K SH3 domain, MW = 9.6 kD) at pH 6, H(C)N, the1H/15N projection, produced observable cross peaks within 20 min. and was completely selective for the single tryptophan and single histidine. The 3D HCN experiment yielded well-defined cross peaks in 20 h for the13C/15N-labeled origin-specific DNA binding domain from simian virus 40 T-antigen (T-ag-OBD131-259, MW = 15.4 kD) at pH 5.5. Resonances from all six histidines in T-ag-OBD were observed, and 11 of the 121H and13C chemical shifts and 10 of the 1215N chemical shifts were determined. The13C dimension proved essential in assignment of the multiply overlapping1H and15N resonances. From the spectra recorded at a single pH, three of the imidazoles were essentially neutral and the other three were partially protonated (22-37%). HCN yielded strong cross peaks after 18 h on a 2.0 mMsample of phenylmethanesulfonyl fluoride (PMSF)-inhibited α-lytic protease (MW = 19.8 kD) at pH 4.4. No spectra have been obtained, however, of native or boronic acid-inhibited α-lytic protease after 18 h at various temperatures ranging from 5 to 55°C, probably due to efficient relaxation of active-site imidazole1H and/or15N nuclei.

  2. 1H, 13C, 15N and 195Pt NMR studies of Au(III) and Pt(II) chloride organometallics with 2-phenylpyridine.

    PubMed

    Pazderski, Leszek; Pawlak, Tomasz; Sitkowski, Jerzy; Kozerski, Lech; Szłyk, Edward

    2009-11-01

    (1)H, (13)C, (15)N and (195)Pt NMR studies of gold(III) and platinum(II) chloride organometallics with N(1),C(2')-chelated, deprotonated 2-phenylpyridine (2ppy*) of the formulae [Au(2ppy*)Cl(2)], trans(N,N)-[Pt(2ppy*)(2ppy)Cl] and trans(S,N)-[Pt(2ppy*)(DMSO-d(6))Cl] (formed in situ upon dissolving [Pt(2ppy*)(micro-Cl)](2) in DMSO-d(6)) were performed. All signals were unambiguously assigned by HMBC/HSQC methods and the respective (1)H, (13)C and (15)N coordination shifts (i.e. differences between chemical shifts of the same atom in the complex and ligand molecules: Delta(1H)(coord) = delta(1H)(complex) - delta(1H)(ligand), Delta(13C)(coord) = delta(13C)(complex) - delta(13C)(ligand), Delta(15N)(coord) = delta(15N)(complex) - delta(15N)(ligand)), as well as (195)Pt chemical shifts and (1)H-(195)Pt coupling constants discussed in relation to the known molecular structures. Characteristic deshielding of nitrogen-adjacent H(6) protons and metallated C(2') atoms as well as significant shielding of coordinated N(1) nitrogens is discussed in respect to a large set of literature NMR data available for related cyclometallated compounds. PMID:19691018

  3. Structural, stability and electronic properties of C15-AB2 (A = Ti, Zr; B = Cr) intermetallic compounds and their hydrides: An ab initio study

    NASA Astrophysics Data System (ADS)

    Sarhaddi, Reza; Arabi, Hadi; Pourarian, Faiz

    2014-05-01

    The structural, stability and electronic properties of C15-AB2 (A = Ti, Zr; B = Cr) isomeric intermetallic compounds were systematically investigated by using density functional theory (DFT) and plane-wave pseudo-potential (PW-PP) method. The macroscopic properties including the lattice constant, bulk modulus and stability for these compounds were studied before and after hydrogenation. For parent compounds, the enthalpy of formation was evaluated with regard to their bulk modules and electronic structures. After hydrogenation of compounds at different interstitial tetrahedral sites (A2B2, A1B3, B4), a volume expansion was found for hydrides. The stability properties of hydrides characterized the A2B2 sites as the site preference of hydrogen atoms for both compounds. The Miedema's "reverse stability" rule is also satisfied in these compounds as lower the enthalpy of formation for the host compound, the more stable the hydride. Analysis of microscopic properties (electronic structures) after hydrogenation at more stable interstitial site (A2B2) shows that the H atoms interact stronger with the weaker (or non) hydride forming element B (Cr) than the hydride forming element A (Ti/Zr). A correlation was also found between the stability of the hydrides and their electronic structure: the deeper the hydrogen band, the less stable the hydride.

  4. HN-NCA heteronuclear TOCSY-NH experiment for (1)H(N) and (15)N sequential correlations in ((13)C, (15)N) labelled intrinsically disordered proteins.

    PubMed

    Wiedemann, Christoph; Goradia, Nishit; Häfner, Sabine; Herbst, Christian; Görlach, Matthias; Ohlenschläger, Oliver; Ramachandran, Ramadurai

    2015-10-01

    A simple triple resonance NMR experiment that leads to the correlation of the backbone amide resonances of each amino acid residue 'i' with that of residues 'i-1' and 'i+1' in ((13)C, (15)N) labelled intrinsically disordered proteins (IDPs) is presented. The experimental scheme, {HN-NCA heteronuclear TOCSY-NH}, exploits the favourable relaxation properties of IDPs and the presence of (1) J CαN and (2) J CαN couplings to transfer the (15)N x magnetisation from amino acid residue 'i' to adjacent residues via the application of a band-selective (15)N-(13)C(α) heteronuclear cross-polarisation sequence of ~100 ms duration. Employing non-uniform sampling in the indirect dimensions, the efficacy of the approach has been demonstrated by the acquisition of 3D HNN chemical shift correlation spectra of α-synuclein. The experimental performance of the RF pulse sequence has been compared with that of the conventional INEPT-based HN(CA)NH pulse scheme. As the availability of data from both the HCCNH and HNN experiments will make it possible to use the information extracted from one experiment to simplify the analysis of the data of the other and lead to a robust approach for unambiguous backbone and side-chain resonance assignments, a time-saving strategy for the simultaneous collection of HCCNH and HNN data is also described. PMID:26282620

  5. The molecular core in G34.3 + 0.2 - Millimeter interferometric observations of HCO(+), H(C-13)N, H(C-15)N, and SO

    NASA Technical Reports Server (NTRS)

    Carral, Patricia; Welch, William J.

    1992-01-01

    This study presents high-resolution observations of the molecular core in the star-forming region G34.3 + 0.2. Maps at 6-arcsec resolution of emission and absorption of the J = 1 - 0 transitions of HCO(+), H (C-13)N, H(C-15)N, and of the 2(2) - 1(1) transition of SO were obtained in addition to a map of the 3.4-mm continuum emission from the compact H II component. The HCL(+) emission toward G34.3 + 0.2 traces a warm molecular core about 0.9 pc in size. Emission from H (C-13)N is detected over about 0.3 pc. The cometary H II region lies near the edge of the molecular core. The blueshift of the radio recombination lines with respect to the molecular emission suggests that gas from the H II region is accelerated in a champagne flow caused by a steep gradient in the ambient gas density.

  6. Balancing the (carbon) budget: Using linear inverse models to estimate carbon flows and mass-balance 13C:15N labelling experiments in low oxygen sediments.

    NASA Astrophysics Data System (ADS)

    Hunter, William Ross; Van Oevelen, Dick; Witte, Ursula

    2013-04-01

    Over 1 million km2 of seafloor experience permanent low-oxygen conditions within oxygen minimum zones (OMZs). OMZs are predicted to grow as a consequence of climate change, potentially affecting oceanic biogeochemical cycles. The Arabian Sea OMZ impinges upon the western Indian continental margin at bathyal depths (150 - 1500m) producing a strong depth dependent oxygen gradient at the sea floor. The influence of the OMZ upon the short term processing of organic matter by sediment ecosystems was investigated using in situ stable isotope pulse chase experiments. These deployed doses of 13C:15N labeled organic matter onto the sediment surface at four stations from across the OMZ (water depth 540 - 1100 m; [O2] = 0.35 - 15 μM). In order to prevent experimentally anoxia, the mesocosms were not sealed. 13C and 15N labels were traced into sediment, bacteria, fauna and 13C into sediment porewater DIC and DOC. However, the DIC and DOC flux to the water column could not be measured, limiting our capacity to obtain mass-balance for C in each experimental mesocosm. Linear Inverse Modeling (LIM) provides a method to obtain a mass-balanced model of carbon flow that integrates stable-isotope tracer data with community biomass and biogeochemical flux data from a range of sources. Here we present an adaptation of the LIM methodology used to investigate how ecosystem structure influenced carbon flow across the Indian margin OMZ. We demonstrate how oxygen conditions affect food-web complexity, affecting the linkages between the bacteria, foraminifera and metazoan fauna, and their contributions to benthic respiration. The food-web models demonstrate how changes in ecosystem complexity are associated with oxygen availability across the OMZ and allow us to obtain a complete carbon budget for the stationa where stable-isotope labelling experiments were conducted.

  7. Color Tuning in Red/Green Cyanobacteriochrome AnPixJ: Photoisomerization at C15 Causes an Excited-State Destabilization.

    PubMed

    Song, Chen; Narikawa, Rei; Ikeuchi, Masahiko; Gärtner, Wolfgang; Matysik, Jörg

    2015-07-30

    Cyanobacteriochromes (CBCRs) are cyanobacterial phytochrome-like photoreceptors that carry a single or several GAF (cGMP phosphodiesterase/adenylyl cyclase/FhlA) domains in a repetitive manner. Unlike phytochromes that photoswitch between red-absorbing 15Z Pr and far-red-absorbing 15E Pfr states, CBCRs exhibit a much wider spectral activity. One of the best-characterized CBCRs, the phototaxis regulator PixJ of Anabaena sp. PCC 7120, AnPixJ can adopt two thermally stable photoreversible states, a red-absorbing dark state (Pr) and a green-absorbing photoproduct (Pg). Cross-polarization magic-angle spinning (CP/MAS) NMR spectroscopy on AnPixJ assembled in vitro with uniformly (13)C- and (15)N-labeled phycocyanobilin (PCB) chromophore identifies changes of the electronic structure of the chromophore between the two states. Results are compared with the data from red- and far-red-absorbing forms of the complete sensory module of cyanobacterial phytochrome Cph1 aiming at a conceptual understanding of the distinct photoproduct (Pg vs Pfr) absorbances upon Pr photoconversion. The PCB chromophore in the Pr state of both photosensors exhibits very similar spectral features. The photoconversion of Cph1 and the red/green switching AnPixJ C15-Z/E photoisomerization result in a very similar chemical-shift difference (Δδ) pattern having, however, opposite sign. The persistence of this pattern confirms the identity of the photochemical isomerization process, while the difference in its sign demonstrates that the same electronic factors drive into opposite direction. It is proposed that the LUMO energy of the 15E photoproduct is stabilized in Cph1 but destabilized in AnPixJ leading to opposite color shifts upon phototransformation. PMID:26115331

  8. Quantitation of metabolic compartmentation in hyperammonemic brain by natural abundance 13C-NMR detection of 13C-15N coupling patterns and isotopic shifts.

    PubMed

    Lapidot, A; Gopher, A

    1997-02-01

    In the present study, the removal of cerebral ammonia by glutamine synthetase (GS) and by reductive amination of 2-oxoglutarate by glutamate dehydrogenase in the presence of an amino donor group, was determined in hyperammonemic rabbit brains. The 15N enrichments of brain metabolite alpha-amino and amide positions of glutamine, glutamate, and alanine were determined by the indirect detection of 15N-labeled compounds of the 13C-15N spin coupling patterns of natural abundance 13C-NMR spectra. The 13C-NMR spectra of brain extracts were obtained from rabbits infused with 15NH4Cl with or without intraperitoneal infusion of the GS inhibitor, L-methionine DL-sulfoximine, in a reasonable acquisition time period. When 15NH4Cl was infused, [5-15N]glutamine and [2-15N]glutamine concentrations reached 5.2 mumol/100 mg protein and 3.6 mumol/100 mg protein, respectively, which indicates the relatively high activity of reductive amination of 2-oxoglutarate in the glutamate dehydrogenase reaction. The low concentration of [2-15N]glutamate, which is about 30% of that of [2-15N]glutamine obtained in this study, suggests that very little glutamine serves as a precursor of neuronal glutamate. When GS was inhibited by L-methionine DL-sulfoximine, a flux of 15NH4+ via the residual activity of GS was accompanied by an apparent increase of [2-15N]glutamate and [15N]alanine concentrations (2.9 mumol/100 mg protein and 1.8 mumol/100 mg protein, respectively). These findings and those obtained from 13C-13C isotopomer analysis (Lapidot and Gopher, 1994b) suggest that astrocytic 2-oxoglutarate is partially utilized (together with an amino group donor) as a precursor for neuronal glutamate in the hyperammonemic brain when GS is inhibited. This process can partly replace GS activity in metabolizing ammonia in the hyperammonemic rabbit brain. PMID:9057821

  9. Rethinking Sensitized Luminescence in Lanthanide Coordination Polymers and MOFs: Band Sensitization and Water Enhanced Eu Luminescence in [Ln(C15H9O5)3(H2O)3]n (Ln = Eu, Tb).

    PubMed

    Einkauf, Jeffrey D; Kelley, Tanya T; Chan, Benny C; de Lill, Daniel T

    2016-08-15

    A coordination polymer [Ln(C15H9O9)3(H2O)3]n (1-Ln = Eu(III), Tb(III)) assembled from benzophenonedicarboxylate was synthesized and characterized. The organic component is shown to sensitize lanthanide-based emission in both compounds, with quantum yields of 36% (Eu) and 6% (Tb). Luminescence of lanthanide coordination polymers is currently described from a molecular approach. This methodology fails to explain the luminescence of this system. It was found that the band structure of the organic component rather than the molecular triplet state was able to explain the observed luminescence. Deuterated (Ln(C15H9O9)3(D2O)3) and dehydrated (Ln(C15H9O9)3) analogues were also studied. When bound H2O was replaced by D2O, lifetime and emission increased as expected. Upon dehydration, lifetimes increased again, but emission of 1-Eu unexpectedly decreased. This reduction is reasoned through an unprecedented enhancement effect of the compound's luminescence by the OH/OD oscillators in the organic-to-Eu(III) energy transfer process. PMID:27472192

  10. Twinning in Laves Phases by Synchroshear: Atomic Mechanisms and Compositional Control. Final report, May 15, 1997 to August 31, 2001

    SciTech Connect

    Luzzi, David E.; Pope, David P.

    2003-04-07

    Compression tests between 4.2 and 1273 K, compositional variation and conventional transmission electron microscopy were used to investigate the deformation and twinning behavior of C15 HfV2+Nb - based Laves phase alloys. We chose two phase C15/bcc alloys to improve the ambient temperature ductility which has not been found in the single phase Laves intermetallic compound. Transmission electron microscopy revealed that substantial mechanical twinning takes place in the CI5 Laves phase matrix at room temperature and 77 K. A deep minimum in the flow stress, with a drop of nearly 500 MPa, appears at around 77 K in the C15/bcc two-phase alloy with C15 matrix. Since no such anomaly is seen in the bcc phase, we believe that the cause of this can be attributed to mechanical twinning in the CI5 Laves phase. Twin bands observed in the CI5 matrix of deformed samples at both 298 K and 77 K can be classified into three categories by their thicknesses; coarse twin bands about 10nm to several hundreds nm thick, fine twin bands around 3 to 10 nm thick, and ultra fine twin bands with average thickness of 1.5 nm. A high density of ultra-fine twin bands is the characteristic feature of twinning in the C15 matrix. They belong to the <112>(111) twinning system and commonly intersect with each other.

  11. Slip, twinning and transformation in Laves phases. Technical progress report, August 1, 1990--July 31, 1993

    SciTech Connect

    Allen, S.M.; Livingston, J.D.

    1993-01-26

    Research was concentrated on two-phase Ti-TiCr{sub 2} alloys, two- phase Fe-ZrFe{sub 2} alloys, and two-phase ternary Ni-Cu-Mg alloys containing MgNi{sub 2} and MgCu{sub 2} phases. Work demonstrated that a variety of room-temperature deformation processes are possible in Laves phases. A strain-induced phase transformation from C36{r_arrow}C15 structures is one mechanism for plastic deformation in ZrFe{sub 2}. The C15 structure in TiCr{sub 2} deforms by slip and twinning. The microstructure after indentation of specimens containing C36 phases ZrFe{sub 2} and MgNi{sub 2} indicates that a variety of slip systems operate in this form. 8 figs.

  12. Phases and Phase Transitions

    NASA Astrophysics Data System (ADS)

    Gitterman, Moshe

    2014-09-01

    In discussing phase transitions, the first thing that we have to do is to define a phase. This is a concept from thermodynamics and statistical mechanics, where a phase is defined as a homogeneous system. As a simple example, let us consider instant coffee. This consists of coffee powder dissolved in water, and after stirring it we have a homogeneous mixture, i.e., a single phase. If we add to a cup of coffee a spoonful of sugar and stir it well, we still have a single phase -- sweet coffee. However, if we add ten spoonfuls of sugar, then the contents of the cup will no longer be homogeneous, but rather a mixture of two homogeneous systems or phases, sweet liquid coffee on top and coffee-flavored wet sugar at the bottom...

  13. Electron concentration and phase stability in NbCr2-based Laves phase alloys

    SciTech Connect

    Zhu, J.H.; Liaw, P.K.; Liu, C.T.

    1997-05-12

    Phase stability in NbCr{sub 2}-based transition-metal Laves phases was studied, based on the data reported for binary X-Cr, Nb-X, and ternary Nb-Cr-X phase diagrams. It was shown that when the atomic size ratios are kept identical, the average electron concentration factor, e/a, is the dominating factor in controlling the phase stability of NbCr{sub 2}-based transition-metal Laves phases. The e/a ratios for different Laves polytypes were determined as followed: with e/a < 5.76, the C15 structure is stabilized; at an e/a range of 5.88--7.53, the C14 structure is stabilized; with e/a > 7.65, the C15 structure is stabilized again. A further increase in the electron concentration factor (e/a > 8) leads to the disordering of the alloy. The electron concentration effect on the phase stability of Mg-based Laves phases and transition-metal A{sub 3}B intermetallic compounds is also reviewed and compared with the present observations in transition-metal Laves phases. In order to verify the e/a/phase stability relationship experimentally, additions of Cu (with e/a = 11) were selected to replace Cr in the NbCr{sub 2} Laves phase. Experimental results for the ternary Nb-Cr-Cu system are reported and discussed in terms of the correlation between the e/a ratio and phase stability in NbCr{sub 2}-based Laves phases. A new phase was found, which has an average composition of Nb-47Cr-3Cu. Within the solubility limit, the electron concentration and phase stability relationship is obeyed in the Nb-Cr-Cu system.

  14. Characterization of Red/Green Cyanobacteriochrome NpR6012g4 by Solution Nuclear Magnetic Resonance Spectroscopy: A Hydrophobic Pocket for the C15-E,anti Chromophore in the Photoproduct.

    PubMed

    Rockwell, Nathan C; Martin, Shelley S; Lim, Sunghyuk; Lagarias, J Clark; Ames, James B

    2015-06-23

    Cyanobacteriochromes (CBCRs) are cyanobacterial photosensory proteins distantly related to phytochromes. Like phytochromes, CBCRs reversibly photoconvert between a dark-stable state and a photoproduct via photoisomerization of the 15,16-double bond of their linear tetrapyrrole (bilin) chromophores. CBCRs provide cyanobacteria with complete coverage of the visible spectrum and near-ultraviolet region. One CBCR subfamily, the canonical red/green CBCRs typified by AnPixJg2 and NpR6012g4, can function as sensors of light color or intensity because of their great variation in photoproduct stability. The mechanistic basis for detection of green light by the photoproduct state in this subfamily has proven to be a challenging research topic, with competing hydration and trapped-twist models proposed. Here, we use ¹³C-edited and ¹⁵N-edited ¹H-¹H NOESY solution nuclear magnetic resonance spectroscopy to probe changes in chromophore configuration and protein-chromophore interactions in the NpR6012g4 photocycle. Our results confirm a C15-Z,anti configuration for the red-absorbing dark state and reveal a C15-E,anti configuration for the green-absorbing photoproduct. The photoactive chromophore D-ring is located in a hydrophobic environment in the photoproduct, surrounded by both aliphatic and aromatic residues. Characterization of variant proteins demonstrates that no aliphatic residue is essential for photoproduct tuning. Taken together, our results support the trapped-twist model over the hydration model for the red/green photocycle of NpR6012g4. PMID:25989712

  15. Phase relation and microstructure of NbCr{sub 2} Laves intermetallics in ternary Nb-Cr-X alloy systems

    SciTech Connect

    Yoshida, M.; Takasugi, T.

    1997-12-31

    The isothermal phase diagrams of ternary alloy systems Nb-Cr-V and Nb-Cr-Mo are determined by metallography, X-ray diffraction (XRD) and transmission electron microscopy (TEM) equipped with energy dispersive X-ray (EDX). In two alloy systems, the C15 NbCr{sub 2} Laves phases are equilibrated directly with bcc solid solution without forming any intermediate phases. Relatively large amount of ternary elements V and Mo are soluble in the C15 NbCr{sub 2} Laves phases. It is shown that the C15 Laves phases extend along directions so that V occupies Cr site while Mo occupies Nb site. Also, characteristic structure containing micro twins and stacking faults is observed in the C15 Laves phase alloyed with Mo. Bcc phase has a wider solid solution range in the X(=V and Mo)-rich side than the Nb-rich and Cr-rich sides. A variety of duplex microstructures are observed depending on alloy system and alloy composition.

  16. Study of stereospecificity of 1H, 13C, 15N and 77Se shielding constants in the configurational isomers of the selenophene-2-carbaldehyde azine by NMR spectroscopy and MP2-GIAO calculations.

    PubMed

    Afonin, Andrei V; Pavlov, Dmitry V; Albanov, Alexander I; Levanova, Ekaterina P; Levkovskaya, Galina G

    2011-11-01

    In the (1)H and (13)C NMR spectra of selenophene-2-carbaldehyde azine, the (1)H-5, (13)C-3 and (13)C-5 signals of the selenophene ring are shifted to higher frequencies, whereas those of the (1)H-1, (13)C-1, (13)C-2 and (13)C-4 are shifted to lower frequencies on going from the EE to ZZ isomer or from the E moiety to the Z moiety of EZ isomer. The (15)N chemical shift is significantly larger in the EE isomer relative to the ZZ isomer and in the E moiety relative to the Z moiety of EZ isomer. A very pronounced difference (60-65 mg/g) between the (77)Se resonance positions is revealed in the studied azine isomers, the (77)Se peak being shifted to higher frequencies in the ZZ isomer and in the Z moiety of EZ isomer. The trends in the changes of the measured chemical shifts are reasonably reproduced by the GIAO calculations at the MP2 level of the (1)H, (13)C, (15)N and (77)Se shielding constants in the energy-favorable conformation with the syn orientation of both selenophene rings relative to the C = N groups. The NBO analysis suggests that such an arrangement of the selenophene rings may take place because of a higher energy of some intramolecular interactions. PMID:22002712

  17. Moon Phases

    ERIC Educational Resources Information Center

    Riddle, Bob

    2010-01-01

    When teaching Moon phases, the focus seems to be on the sequence of Moon phases and, in some grade levels, how Moon phases occur. Either focus can sometimes be a challenge, especially without the use of models and observations of the Moon. In this month's column, the author describes some of the lessons that he uses to teach the phases of the Moon…

  18. Hyperfine spectroscopic study of Laves phase HfFe 2

    NASA Astrophysics Data System (ADS)

    Belošević-Čavor, J.; Novaković, N.; Cekić, B.; Ivanović, N.; Manasijević, M.

    2004-05-01

    Hyperfine fields in HfFe 2 were measured at 181Ta probe using the time-differential perturbed angular correlation method (TDPAC) in the temperature range 78-1200 K. Analysis of the spectra revealed two interactions with hyperfine fields of 13.82(7) T and 8.0(2) T, at 293 K. First is ascribed to the interaction at the 8a position in the cubic C15 structure. The second can be assigned to a minor amount of hexagonal C14 phase, or to an irregular position of the probe in the C15 lattice. Results of calculations using LAPW-WIEN97 are in a good agreement with experiment.

  19. Phase stability of laves intermetallics in stainless steel-zirconium alloys.

    SciTech Connect

    Abraham, D. P.

    1999-04-08

    Phase transformations occurring in a stainless steel-15 wt% zirconium (SS-15Zr) alloy were studied by in situ neutron diffraction. Neutron diffraction patterns as a function of time were obtained on alloys that were held at various elevated temperatures (1084-1275 C). As-cast SS-15Zr alloys contain ferrite, austenite, ZrFe{sub 2}-type Laves polytypes C36 and C15, and small amounts of a Fe{sub 23}Zr{sub 6}-type intermetallic. Annealing at high temperatures resulted in an increase of the Fe{sub 23}Zr{sub 6}, intermetallic content. The C15 Laves polytype is the equilibrium phase for T {le} 1230 C; C36 is the stable polytype at higher temperatures ({approximately}1275 C). Phase changes were slow for temperatures <1100 C.These findings have important implications for use of the SS-15Zr alloy as a nuclear waste form.

  20. Study of fatigue and fracture behavior of NbCr{sub 2}-based alloys and intermetallic materials: Phase stability in NbCr{sub 2} Laves phase alloys

    SciTech Connect

    Zhu, J.H.; Liaw, P.K.; Liu, C.T.

    1996-08-01

    Phase stability in NbCr{sub 2}-based transition-metal Laves phases is studied in this paper, using data from binary X-Cr, Nb-X, and ternary Nb-Cr-X phase diagrams. It was shown that when the atomic size ratios are kept identical, the average electron concentration factor (e/a = the average number of electrons per atom outside the closed shells of the component atoms) is the determinate factor in controlling the phase stability of NbCr{sub 2}-based transition-metal Laves phases. The e/a ratios for different Laves phase structures were determined as follows: with e/a < 5.76, the C15 structure is stabilized; at an e/a range of 5.88-7.53, the C14 structure is stabilized; with e/a > 7.65, the C15 structure was stabilized again. A further increase in the electron concentration factor (e/a > 8) leads to the disordering of the alloy. The electron concentration effect on the phase stability of transition-metal A{sub 3}B intermetallic compounds and Mg-based Laves phases is also reviewed and compared with the present observations in transition-metal Laves phases.

  1. PHASE DETECTOR

    DOEpatents

    Kippenhan, D.O.

    1959-09-01

    A phase detector circuit is described for use at very high frequencies of the order of 50 megacycles. The detector circuit includes a pair of rectifiers inverted relative to each other. One voltage to be compared is applied to the two rectifiers in phase opposition and the other voltage to be compared is commonly applied to the two rectifiers. The two result:ng d-c voltages derived from the rectifiers are combined in phase opposition to produce a single d-c voltage having amplitude and polarity characteristics dependent upon the phase relation between the signals to be compared. Principal novelty resides in the employment of a half-wave transmission line to derive the phase opposing signals from the first voltage to be compared for application to the two rectifiers in place of the transformer commonly utilized for such purpose in phase detector circuits for operation at lower frequency.

  2. Slip, twinning and transformation in Laves phases. [Ti-TiCr[sub 2]; Fe-ZrFe[sub 2]; Ni-Cu-Mg containing MgNi[sub 2] and MgCu[sub 2

    SciTech Connect

    Allen, S.M.; Livingston, J.D.

    1993-01-26

    Research was concentrated on two-phase Ti-TiCr[sub 2] alloys, two- phase Fe-ZrFe[sub 2] alloys, and two-phase ternary Ni-Cu-Mg alloys containing MgNi[sub 2] and MgCu[sub 2] phases. Work demonstrated that a variety of room-temperature deformation processes are possible in Laves phases. A strain-induced phase transformation from C36[r arrow]C15 structures is one mechanism for plastic deformation in ZrFe[sub 2]. The C15 structure in TiCr[sub 2] deforms by slip and twinning. The microstructure after indentation of specimens containing C36 phases ZrFe[sub 2] and MgNi[sub 2] indicates that a variety of slip systems operate in this form. 8 figs.

  3. Venus Phasing.

    ERIC Educational Resources Information Center

    Riddle, Bob

    1997-01-01

    Presents a science activity designed to introduce students to the geocentric and heliocentric models of the universe. Helps students discover why phase changes on Venus knocked Earth out of the center of the universe. (DKM)

  4. Effect of lattice anharmonicity in the structural phase transformation of Laves phase HfV2 alloy: A first-principles investigation

    SciTech Connect

    Krcmar, Maja; Fu, Chong Long

    2013-01-01

    First-principles theory was developed to study the structural phase transformations in the Laves phase HfV2 alloy. We explored the energy landscape and established the role of lattice anharmonicity underlying the structural phase transitions. Our approach is based on a phenomenological Landau theory for the structural phase transition and a mean-field approximation for the free energy. First-principles calculations were utilized to obtain the distortion energy as a function of relevant deformations, and to deduce parameters for constructing the free energy. Our result for the phase transition temperature of HfV2 is in good agreement with experiment. We find that the high-temperature cubic C15 phase is stabilized by the effect of lattice anharmonicity. The theory also predicts an anomalous increase in shear modulus with increasing temperature for systems where the anharmonicity is pronounced.

  5. Corrosion Resistances of Iron-Based Amorphous Metals with Yttrium and Tungsten Additions in Hot Calcium Chloride Brine & Natural Seawater: Fe48Mo14CR15Y2C15B6 and Variants

    SciTech Connect

    Farmer, J; Haslam, J; Day, S; Lian, T; Saw, C; Hailey, P; Choi, J; Yang, N; Blue, C; Peter, W; Payer, J; Perepezko, J; Hildal, K; Branagan, D J; Beardsley, M B; Aprigliano, L

    2006-10-12

    The passive film stability of several Fe-based amorphous metal formulations have been found to be comparable to that of stainless steels and Ni-based Alloy C-22 (UNS No. N06022), based on electrochemical measurements of the passive film breakdown potential and general corrosion rates. Electrochemical studies of the passive film stability of SAM1651 are reported here. Chromium (Cr), molybdenum (Mo) and tungsten (W) provide corrosion resistance; boron (B) enables glass formation; and rare earths such as yttrium (Y) lower critical cooling rate (CCR). Yttrium-containing SAM1651, also known as SAM7 (Fe{sub 48.0}Cr{sub 15.0}Mo{sub 14.0}B{sub 6.0}C{sub 15.0}Y{sub 2.0}), has a critical cooling rate (CCR) of approximately 80 Kelvin per second, while yttrium-free SAM2X5 (Fe{sub 49.7}Cr{sub 17.7}Mn{sub 1.9}Mo{sub 7.4}W{sub 1.6}B{sub 15.2}C{sub 3.8}Si{sub 2.4}) has a higher critical cooling rate of approximately 600 Kelvin per second. SAM1651's low CCR enables it to be rendered as a completely amorphous material in practical materials processes. While the yttrium enables a low CCR to be achieved, it makes the material relatively difficult to atomize, due to increases in melt viscosity. Consequently, the powders have irregular shape, which makes pneumatic conveyance during thermal spray deposition difficult. The reference material, nickel-based Alloy C-22, is an outstanding corrosion-resistant engineering material. Even so, crevice corrosion has been observed with C-22 in hot sodium chloride environments without buffer or inhibitor. SAM1651 may also experience crevice corrosion under sufficiently harsh conditions. Both Alloy C-22 and Type 316L stainless lose their resistance to corrosion during thermal spraying, due to the formation of deleterious intermetallic phases which depletes the matrix of key alloy elements, whereas SAM1651 can be applied as coatings with the same corrosion resistance as a fully-dense completely amorphous melt-spun ribbon, provided that its amorphous

  6. Phase Won.

    ERIC Educational Resources Information Center

    Kocher, Erik

    2003-01-01

    Describes ten steps involved in successful renovation of a college recreation center. They are as follows: hire the right architect, be realistic about costs, devise a plan, do a mental walk through, approach the renovation in phases, communicate to users, expect lost revenue and displacement issues, continue to communicate with architects and…

  7. Transition of Bery Phase and Pancharatnam Phase and Phase Change

    NASA Astrophysics Data System (ADS)

    Fu, Guolan; Pan, Hui; Wang, Zisheng

    2016-07-01

    Berry Phase and time-dependent Pancharatnam phase are investigated for nuclear spin polarization in a liquid by a rotation magnetic field, where two-state mixture effect is exactly included in the geometric phases. We find that when the system of nuclear spin polarization is in the unpolarized state, the transitive phenomena of both Berry phase and Pancharatnam phase are taken place. For the polarized system, in contrast, such a transition is not taken place. It is obvious that the transitions of geometric phase correspond to the phase change of physical system.

  8. Point Defects in Binary Laves-Phase Alloys

    SciTech Connect

    Liaw, P.K.; Liu, C.T.; Pike, L.M.; Zhu, J.H.

    1998-11-30

    Point defect mechanisms in the binary C15 NbCr{sub 2} and NbCo{sub 2}, and C14 NbFe{sub 2} systems on both sides of stoichiometry was studied and clarified by both bulk density and X-ray lattice parameter measurements. It was found that the vacancy concentrations in these systems after quenching from 1000 C are essentially zero. The constitutional defects on both sides of stoichiometry for these systems were found to be of the anti-site type in comparison with the model predictions. However, thermal vacancies exhibiting a maximum at the stoichiometric composition were obtained in NbCr{sub 2} laves phase alloys after quenching from 1400 C. These could be completely eliminated by annealing at 1000 C. Anti-site hardening was found on both sides of stoichiometry for all three Laves phase systems studied. Furthermore, the thermal vacancies in NbCr{sub 2} alloys after quenching from 1400 C were found to soften the Laves phase. The anti-site hardening of the Laves phases is similar to that of the B2 compounds, while the thermal vacancy softening is unique to the Laves phase. Both the anti-site defects and thermal vacancies do not significantly affect the fracture toughness of the Laves phases.

  9. Point Defects in Binary Laves-Phase Alloys

    SciTech Connect

    Liaw, P.K.; Liu, C.T.; Pike, L.M.; Zhu, J.H.

    1999-01-11

    Point defects in the binary C15 NbCrQ and NbCoz, and C 14 NbFe2 systems on both sides of stoichiometry were studied by both bulk density and X-ray Iattiee parameter measurements. It was found that the vacancy concentrations in these systems after quenching from 1000"C are essentially zero. The constitutional defects on both sides of stoichiometry for these systems were found to be of the anti-site type in comparison with the model predictions. Thermal vacancies exhibiting a maximum at the stoichiometric composition were obtained in NbCr2 Laves phase alloys after quenching from 1400"C. However, there are essentially no thermal vacancies in NbFe2 alloys after quenching from 1300oC. Anti-site hardening was found on both sides of stoichiometry for all the tie Laves phase systems studied, while the thermal vacancies in NbCr2 alloys quenched from 1400'C were found to soften the Laves phase. The anti-site hardening of the Laves phases is similar to that of the B2 compounds and the thermal vacancy softening is unique to the Laves phase. Neither the anti-site defects nor the thermal vacancies affect the fracture toughness of the Laves phases significantly.

  10. GC-MS determination of ratios of stable-isotope labelled to natural urea using [13C15N2]urea for studying urea kinetics in serum and as a means to validate routine methods for the quantitative assay of urea in dialysate.

    PubMed

    Wolthers, B G; Tepper, T; Withag, A; Nagel, G T; de Haan, T H; van Leeuwen, J J; Stegeman, C A; Huisman, R M

    1994-02-01

    A GC-MS determination of urea in serum or spent dialysate is described, using 13C15N2-labelled urea and assaying the area ratio of labelled to natural urea by mass fragmentographic monitoring of fragments m/e 153 and 156, after its eventual conversion into the trimethylsilylether-derivative of 2-hydroxypyrimidine. The procedure can be successfully applied in the follow-up of the disappearance of labelled urea in serum after intravenous injection in man, enabling kinetic parameters of urea to be established, e.g. for purposes of studying the effectiveness of dialysis procedures. Furthermore the method can be used for validation of routine methods for measuring urea in other fluids, in particular dialysate. Examples are given of both applications of the GC-MS method described. PMID:8033352

  11. Unfolding wrapped phase

    NASA Astrophysics Data System (ADS)

    Treviño-Palacios, Carlos Gerardo

    2015-11-01

    Phase unwrapping is the final step in phase extraction methods, which consists of recovering the correct phase from the wrapped phase by removing 2π discontinuities. The difference between the correct phase and the wrapped phase is the phase wrapping map. A new method for phase unwrapping is presented by identifying the phase wrapping map as a sequence of binary valued intermediate wrapping maps and iteratively removing them producing the correct phase by phase-wrapped unfolding. A path-following algorithm is presented to exemplify the phase wrapped unfolding method.

  12. Four-phase differential phase shift resolver

    NASA Technical Reports Server (NTRS)

    Hopkins, P. M.; Wallingford, W. M.

    1973-01-01

    Two systems have been developed to resolve phase uncertainty without transmitting reference signals. In both methods signal is impressed on carrier as differential, rather than absolute, phase shift. At the receiver four-phase demodulation and logic process unambiguously resolves differential phase shift of input carrier.

  13. Microstructures and Mechanical Properties of Two-Phase Alloys Based on NbCr(2)

    SciTech Connect

    Cady, C.M.; Chen, K.C.; Kotula, P.G.; Mauro, M.E.; Thoma, D.J.

    1998-12-07

    A two-phase, Nb-Cr-Ti alloy (bee+ C15 Laves phase) has been developed using several alloy design methodologies. In effort to understand processing-microstructure-property relationships, diffment processing routes were employed. The resulting microstructure and mechanical properties are discussed and compared. Plasma arc-melted samples served to establish baseline, . . . as-cast properties. In addition, a novel processing technique, involving decomposition of a supersaturated and metastable precursor phase during hot isostatic pressing (HIP), was used to produce a refined, equilibrium two-phase microstructure. Quasi-static compression tests as a ~ function of temperature were performed on both alloy types. Different deformation mechanisms were encountered based upon temperature and microstructure.

  14. Laves phase-based materials: Microstructure, deformation modes and properties

    SciTech Connect

    Kumar, K.S.

    1997-12-31

    Intermetallic compounds with the AB{sub 2} stoichiometry can exist with the C14, C15 or C36 structures, otherwise called Laves phases. In the past, single-phase Laves compounds, particularly Mg-containing binary compounds, have been examined to obtain an understanding of the dislocation structures as well as their mobility; alternately, effort has also been expended in examining the polytypic transformations that occur in such Laves phases. More recently however, Laves phases and polyphase alloys containing the Laves phase have been examined with the intent of developing structural alloys for elevated temperature applications. Specifically, alloys based on the Cr-Group IV (Ti, Zr, Hf) and Group V (Nb, Ta) elements as well as the ternary V-Hf-Nb system have been the focus of several investigations. Physical and mechanical properties have been measured, and microstructure has been characterized as a function of heat treatment. Deformation modes have been re-examined in detail. New ideas based on synchroshear have been put forth to explain the polytypic transformations that occur in these systems, and have been extended to also explain twinning and slip. Earlier observations are first summarized and then these recent advances are reviewed and the potential for these materials is assessed. 57 refs., 8 figs.

  15. TEM investigation on the low temperature phase of HfV{sub 2}

    SciTech Connect

    Chu, Fuming; Mitchell, T.E.

    1995-04-01

    HfV2, a particularly attractive C15 Laves phase structural material, undergoes a structural transformation at 115K. A tentative reciprocal lattice for low-temperature HfV2 based on a combination of selected area diffraction patterns is illustrated. The results reveal structural characteristics inconsistent with earlier claims by other investigators. Further and detailed studies are under way, using a combination of CBED and synchrotron diffraction to determine the low-temperature structure`s crystal symmetry, lattice parameters, and atomic positions.

  16. Study of fatigue and fracture behavior of NbCr{sub 2}-based alloys: Phase stability in Nb-Cr-Ni ternary system

    SciTech Connect

    Zhu, J.H.; Liaw, P.K.; Liu, C.T.

    1997-12-01

    Phase stability in a ternary Nb-Cr-Ni Laves phase system was studied in this paper. Their previous study in NbCr{sub 2}-based transition-metal Laves phases has shown that the average electron concentration factor, e/a, is the dominating factor in controlling the phase stability of NbCr{sub 2}-based Laves phases when the atomic size ratios are kept identical. Since Ni has ten out-shell electrons, the substitution of Ni for Cr in NbCr{sub 2} will increase the average electron concentration of the alloy, thus leading to the change of the crystal structures from C15 to C14. In this paper, a number of pseudo-binary Nb(Cr,Ni){sub 2} alloys were prepared, and the crystal structures of the alloys after a long heat-treatment at 1000 C as a function of the Ni content were determined by the X-ray diffraction technique. The boundaries of the C15/C14 transition were determined and compared to their previous predictions. It was found that the electron concentration and phase stability correlation is obeyed in the Nb-Cr-Ni system. However, the e/a ratio corresponding to the C15/C14 phase transition was found to move to a higher value than the predicted one. The changes in the lattice constant, Vickers hardness and fracture toughness were also determined as a function of the Ni content, which were discussed in light of the phase stability difference of the alloys.

  17. An Exhaustive Symmetry Approach to Structure Determination: Phase Transitions in Bi2Sn2O7.

    PubMed

    Lewis, James W; Payne, Julia L; Evans, Ivana Radosavljevic; Stokes, Harold T; Campbell, Branton J; Evans, John S O

    2016-06-29

    The exploitable properties of many materials are intimately linked to symmetry-lowering structural phase transitions. We present an automated and exhaustive symmetry-mode method for systematically exploring and solving such structures which will be widely applicable to a range of functional materials. We exemplify the method with an investigation of the Bi2Sn2O7 pyrochlore, which has been shown to undergo transitions from a parent γ cubic phase to β and α structures on cooling. The results include the first reliable structural model for β-Bi2Sn2O7 (orthorhombic Aba2, a = 7.571833(8), b = 21.41262(2), and c = 15.132459(14) Å) and a much simpler description of α-Bi2Sn2O7 (monoclinic Cc, a = 13.15493(6), b = 7.54118(4), and c = 15.07672(7) Å, β = 125.0120(3)°) than has been presented previously. We use the symmetry-mode basis to describe the phase transition in terms of coupled rotations of the Bi2O' anti-cristobalite framework, which allow Bi atoms to adopt low-symmetry coordination environments favored by lone-pair cations. PMID:27248317

  18. Assessment of the compositional influences on the toughness of TiCr{sub 2}-base Laves phase alloys

    SciTech Connect

    Chen, K.C.; Allen, S.M.; Livingston, J.D.

    1997-12-31

    Systematic studies of alloys based on TiCr{sub 2} have been performed in order to improve the toughness of Laves phase intermetallics. The extent to which alloy compositions and annealing treatments influence the toughness was quantified by Vickers indentation. The single-phase Laves behavior was first established by studying stoichiometric and nonstoichiometric TiCr{sub 2}. Next, alloying effects were investigated with ternary Laves phases based on TiCr{sub 2}. Different microstructures of two-phase alloys consisting of (Ti,Cr)-bcc + TiCr{sub 2} were also examined. Various toughening theories based on vacancies, site-substitutions, crystal structure (C14, C36, or C15) stabilization, and the presence of a second phase were evaluated. The most effective factors improving the toughness of TiCr{sub 2} were determined, and toughening mechanisms are suggested.

  19. Phase Coexistence in a Dynamic Phase Diagram.

    PubMed

    Gentile, Luigi; Coppola, Luigi; Balog, Sandor; Mortensen, Kell; Ranieri, Giuseppe A; Olsson, Ulf

    2015-08-01

    Metastability and phase coexistence are important concepts in colloidal science. Typically, the phase diagram of colloidal systems is considered at the equilibrium without the presence of an external field. However, several studies have reported phase transition under mechanical deformation. The reason behind phase coexistence under shear flow is not fully understood. Here, multilamellar vesicle (MLV)-to-sponge (L3 ) and MLV-to-Lα transitions upon increasing temperature are detected using flow small-angle neutron scattering techniques. Coexistence of Lα and MLV phases at 40 °C under shear flow is detected by using flow NMR spectroscopy. The unusual rheological behavior observed by studying the lamellar phase of a non-ionic surfactant is explained using (2) H NMR and diffusion flow NMR spectroscopy with the coexistence of planar lamellar-multilamellar vesicles. Moreover, a dynamic phase diagram over a wide range of temperatures is proposed. PMID:26083451

  20. CrowdPhase: crowdsourcing the phase problem

    SciTech Connect

    Jorda, Julien; Sawaya, Michael R.; Yeates, Todd O.

    2014-06-01

    The idea of attacking the phase problem by crowdsourcing is introduced. Using an interactive, multi-player, web-based system, participants work simultaneously to select phase sets that correspond to better electron-density maps in order to solve low-resolution phasing problems. The human mind innately excels at some complex tasks that are difficult to solve using computers alone. For complex problems amenable to parallelization, strategies can be developed to exploit human intelligence in a collective form: such approaches are sometimes referred to as ‘crowdsourcing’. Here, a first attempt at a crowdsourced approach for low-resolution ab initio phasing in macromolecular crystallography is proposed. A collaborative online game named CrowdPhase was designed, which relies on a human-powered genetic algorithm, where players control the selection mechanism during the evolutionary process. The algorithm starts from a population of ‘individuals’, each with a random genetic makeup, in this case a map prepared from a random set of phases, and tries to cause the population to evolve towards individuals with better phases based on Darwinian survival of the fittest. Players apply their pattern-recognition capabilities to evaluate the electron-density maps generated from these sets of phases and to select the fittest individuals. A user-friendly interface, a training stage and a competitive scoring system foster a network of well trained players who can guide the genetic algorithm towards better solutions from generation to generation via gameplay. CrowdPhase was applied to two synthetic low-resolution phasing puzzles and it was shown that players could successfully obtain phase sets in the 30° phase error range and corresponding molecular envelopes showing agreement with the low-resolution models. The successful preliminary studies suggest that with further development the crowdsourcing approach could fill a gap in current crystallographic methods by making it

  1. Topologically close-packed phases in binary transition-metal compounds: matching high-throughput ab initio calculations to an empirical structure map

    NASA Astrophysics Data System (ADS)

    Hammerschmidt, T.; Bialon, A. F.; Pettifor, D. G.; Drautz, R.

    2013-11-01

    In steels and single-crystal superalloys the control of the formation of topologically close-packed (TCP) phases is critical for the performance of the material. The structural stability of TCP phases in multi-component transition-metal alloys may be rationalized in terms of the average valence-electron count \\bar {N} and the composition-dependent relative volume-difference \\overline {\\Delta V/V} . We elucidate the interplay of these factors by comparing density-functional theory calculations to an empirical structure map based on experimental data. In particular, we calculate the heat of formation for the TCP phases A15, C14, C15, C36, χ, μ and σ for all possible binary occupations of the Wyckoff positions. We discuss the isovalent systems V/Nb-Ta to highlight the role of atomic-size difference and observe the expected stabilization of C14/C15/C36/μ by \\overline {\\Delta V/V} at ΔN = 0 in V-Ta. In the systems V/Nb-Re, we focus on the well-known trend of A15 → σ → χ stability with increasing \\bar {N} and show that the influence of \\overline {\\Delta V/V} is too weak to stabilize C14/C15/C36/μ in Nb-Re. As an example for a significant influence of both \\bar {N} and \\overline {\\Delta V/V} , we also consider the systems Cr/Mo-Co. Here the sequence A15 → σ → χ is observed in both systems but in Mo-Co the large size-mismatch stabilizes C14/C15/C36/μ. We also include V/Nb-Co that cover the entire valence range of TCP stability and also show the stabilization of C14/C15/C36/μ. Moreover, the combination of a large volume-difference with a large mismatch in valence-electron count reduces the stability of the A15/σ/χ phases in Nb-Co as compared to V-Co. By comparison to non-magnetic calculations we also find that magnetism is of minor importance for the structural stability of TCP phases in Cr/Mo-Co and in V/Nb-Co.

  2. Non-equilibrium phases and phase diagrams

    SciTech Connect

    Massalski, T.B.; Rizzo, H.F.

    1988-03-01

    In this paper we consider the degree of usefulness of the phase diagram and the related thermodynamics in predicting and understanding the formation of metastable phases during quenching, or during low-temperature solid-state interdiffusion, or during co-deposition. Recent research has demonstrated that many of such metastable phases are formed because the more stable intermediate phases that are favored thermodynamically are nevertheless bypassed kinetically. The kinetic elimination of intermediate phases provides conditions where a metastable equilibrium can be established at low temperatures between the supercooled liquid and the terminal solid solutions, leading to metastable partitioned two-phase regions. Alternatively, the range of the metastable phases may be governed by the T/sub 0/ principle related to the crossover of the respective free energy curves, or may be controlled mainly by kinetic considerations. Which particular thermodynamic conditions apply appears to depend on the initial form of the phase diagram and the specific technique used. The occurrence of massive transformations also is discussed. 34 refs., 10 figs.

  3. Map-likelihood phasing

    PubMed Central

    Terwilliger, Thomas C.

    2001-01-01

    The recently developed technique of maximum-likelihood density modification [Terwilliger (2000 ▶), Acta Cryst. D56, 965–972] allows a calculation of phase probabilities based on the likelihood of the electron-density map to be carried out separately from the calculation of any prior phase probabilities. Here, it is shown that phase-probability distributions calculated from the map-likelihood function alone can be highly accurate and that they show minimal bias towards the phases used to initiate the calculation. Map-likelihood phase probabilities depend upon expected characteristics of the electron-density map, such as a defined solvent region and expected electron-density distributions within the solvent region and the region occupied by a macromolecule. In the simplest case, map-likelihood phase-probability distributions are largely based on the flatness of the solvent region. Though map-likelihood phases can be calculated without prior phase information, they are greatly enhanced by high-quality starting phases. This leads to the technique of prime-and-switch phasing for removing model bias. In prime-and-switch phasing, biased phases such as those from a model are used to prime or initiate map-likelihood phasing, then final phases are obtained from map-likelihood phasing alone. Map-likelihood phasing can be applied in cases with solvent content as low as 30%. Potential applications of map-likelihood phasing include unbiased phase calculation from molecular-replacement models, iterative model building, unbiased electron-density maps for cases where 2Fo − Fc or σA-weighted maps would currently be used, structure validation and ab initio phase determination from solvent masks, non-crystallographic symmetry or other knowledge about expected electron density. PMID:11717488

  4. CrowdPhase: crowdsourcing the phase problem.

    PubMed

    Jorda, Julien; Sawaya, Michael R; Yeates, Todd O

    2014-06-01

    The human mind innately excels at some complex tasks that are difficult to solve using computers alone. For complex problems amenable to parallelization, strategies can be developed to exploit human intelligence in a collective form: such approaches are sometimes referred to as `crowdsourcing'. Here, a first attempt at a crowdsourced approach for low-resolution ab initio phasing in macromolecular crystallography is proposed. A collaborative online game named CrowdPhase was designed, which relies on a human-powered genetic algorithm, where players control the selection mechanism during the evolutionary process. The algorithm starts from a population of `individuals', each with a random genetic makeup, in this case a map prepared from a random set of phases, and tries to cause the population to evolve towards individuals with better phases based on Darwinian survival of the fittest. Players apply their pattern-recognition capabilities to evaluate the electron-density maps generated from these sets of phases and to select the fittest individuals. A user-friendly interface, a training stage and a competitive scoring system foster a network of well trained players who can guide the genetic algorithm towards better solutions from generation to generation via gameplay. CrowdPhase was applied to two synthetic low-resolution phasing puzzles and it was shown that players could successfully obtain phase sets in the 30° phase error range and corresponding molecular envelopes showing agreement with the low-resolution models. The successful preliminary studies suggest that with further development the crowdsourcing approach could fill a gap in current crystallographic methods by making it possible to extract meaningful information in cases where limited resolution might otherwise prevent initial phasing. PMID:24914965

  5. CrowdPhase: crowdsourcing the phase problem

    PubMed Central

    Jorda, Julien; Sawaya, Michael R.; Yeates, Todd O.

    2014-01-01

    The human mind innately excels at some complex tasks that are difficult to solve using computers alone. For complex problems amenable to parallelization, strategies can be developed to exploit human intelligence in a collective form: such approaches are sometimes referred to as ‘crowdsourcing’. Here, a first attempt at a crowdsourced approach for low-resolution ab initio phasing in macromolecular crystallography is proposed. A collaborative online game named CrowdPhase was designed, which relies on a human-powered genetic algorithm, where players control the selection mechanism during the evolutionary process. The algorithm starts from a population of ‘individuals’, each with a random genetic makeup, in this case a map prepared from a random set of phases, and tries to cause the population to evolve towards individuals with better phases based on Darwinian survival of the fittest. Players apply their pattern-recognition capabilities to evaluate the electron-density maps generated from these sets of phases and to select the fittest individuals. A user-friendly interface, a training stage and a competitive scoring system foster a network of well trained players who can guide the genetic algorithm towards better solutions from generation to generation via gameplay. CrowdPhase was applied to two synthetic low-resolution phasing puzzles and it was shown that players could successfully obtain phase sets in the 30° phase error range and corresponding molecular envelopes showing agreement with the low-resolution models. The successful preliminary studies suggest that with further development the crowdsourcing approach could fill a gap in current crystallographic methods by making it possible to extract meaningful information in cases where limited resolution might otherwise prevent initial phasing. PMID:24914965

  6. Propagating phase interface with intermediate interfacial phase: Phase field approach

    NASA Astrophysics Data System (ADS)

    Momeni, Kasra; Levitas, Valery I.

    2014-05-01

    An advanced three-phase phase field approach (PFA) is suggested for a nonequilibrium phase interface that contains an intermediate phase, in particular, a solid-solid interface with a nanometer-sized intermediate melt (IM). A thermodynamic potential in the polar order parameters is developed that satisfies all thermodynamic equilibrium and stability conditions. The special form of the gradient energy allowed us to include the interaction of two solid-melt interfaces via an intermediate melt and obtain a well-posed problem and mesh-independent solutions. It is proved that for stationary 1D solutions to two Ginzburg-Landau equations for three phases, the local energy at each point is equal to the gradient energy. Simulations are performed for β ↔δ phase transformations (PTs) via IM in an HMX energetic material. The obtained energy IM width dependence is described by generalized force-balance models for short- and long-range interaction forces between interfaces but not far from the melting temperature. A force-balance model is developed that describes phase field results even 100 K below the melting temperature. The effects of the ratios of width and energies of solid-solid and solid-melt interfaces, temperature, and the parameter characterizing interaction of two solid-melt interfaces, on the structure, width, energy of the IM and interface velocity are determined by finite element method. Depending on parameters, the IM may appear by continuous or discontinuous barrierless disordering or via critical nucleus due to thermal fluctuations. The IM may appear during heating and persist during cooling at temperatures well below than it follows from sharp-interface approach. On the other hand, for some parameters when IM is expected, it does not form, producing an IM-free gap. The developed PFA represents a quite general three-phase model and can be extended to other physical phenomena, such as martensitic PTs, surface-induced premelting and PTs, premelting

  7. Simplified phase detector

    NASA Technical Reports Server (NTRS)

    Hershey, L. M.

    1979-01-01

    Tanlick sine-wave phase detector gives dc output voltage nearly proportional to phase difference between oscillator signal and reference signal. Device may be used for systems in which signal-to-noise ratio is high.

  8. Digital quadrature phase detection

    DOEpatents

    Smith, J.A.; Johnson, J.A.

    1992-05-26

    A system for detecting the phase of a frequency or phase modulated signal that includes digital quadrature sampling of the frequency or phase modulated signal at two times that are one quarter of a cycle of a reference signal apart, determination of the arctangent of the ratio of a first sampling of the frequency or phase modulated signal to the second sampling of the frequency or phase modulated signal, and a determination of quadrant in which the phase determination is increased by 2[pi] when the quadrant changes from the first quadrant to the fourth quadrant and decreased by 2[pi] when the quadrant changes from the fourth quadrant to the first quadrant whereby the absolute phase of the frequency or phase modulated signal can be determined using an arbitrary reference convention. 6 figs.

  9. Digital quadrature phase detection

    DOEpatents

    Smith, James A.; Johnson, John A.

    1992-01-01

    A system for detecting the phase of a frequency of phase modulated signal that includes digital quadrature sampling of the frequency or phase modulated signal at two times that are one quarter of a cycle of a reference signal apart, determination of the arctangent of the ratio of a first sampling of the frequency or phase modulated signal to the second sampling of the frequency or phase modulated signal, and a determination of quadrant in which the phase determination is increased by 2.pi. when the quadrant changes from the first quadrant to the fourth quadrant and decreased by 2.pi. when the quadrant changes from the fourth quadrant to the first quadrant whereby the absolute phase of the frequency or phase modulated signal can be determined using an arbitrary reference convention.

  10. Phase jitter in a differential phase experiment.

    NASA Technical Reports Server (NTRS)

    Tanenbaum, B. S.; Connolly, D. J.; Austin, G. L.

    1973-01-01

    Austin (1971) had concluded that, because of the 'phase jitter,' the differential phase experiment is useful over a more limited height range than the differential absorption experiment. Several observations are presented to show that this conclusion is premature. It is pointed out that the logical basis of the differential absorption experiment also requires that the O- and X-mode echoes, at a given time, come from the same irregularities. Austin's calculations are believed to contain a systematic error above 80 km.

  11. Perceptions about Moon Phases.

    ERIC Educational Resources Information Center

    Rider, Steven

    2002-01-01

    Presents research on different techniques to determine the level of understanding among middle school students regarding the phases of the moon. Quotes student responses to provide some insight into students' level of understanding of general knowledge about the moon, moon phases, and modeling the phases. Presents implications for teachers. (KHR)

  12. Acute phase reaction and acute phase proteins*

    PubMed Central

    Gruys, E.; Toussaint, M.J.M.; Niewold, T.A.; Koopmans, S.J.

    2005-01-01

    A review of the systemic acute phase reaction with major cytokines involved, and the hepatic metabolic changes, negative and positive acute phase proteins (APPs) with function and associated pathology is given. It appears that APPs represent appropriate analytes for assessment of animal health. Whereas they represent non-specific markers as biological effect reactants, they can be used for assessing nutritional deficits and reactive processes, especially when positive and negative acute phase variables are combined in an index. When such acute phase index is applied to separate healthy animals from animals with some disease, much better results are obtained than with single analytes and statistically acceptable results for culling individual animals may be reached. Unfortunately at present no cheap, comprehensive and easy to use system is available for assessing various acute phase proteins in serum or blood samples at the same time. Protein microarray or fluid phase microchip technology may satisfy this need; and permit simultaneous analysis of numerous analytes in the same small volume sample and enable integration of information derived from systemic reactivity and nutrition with disease specific variables. Applying such technology may help to solve health problems in various countries not only in animal husbandry but also in human populations. PMID:16252337

  13. Phase microscope imaging in phase space

    NASA Astrophysics Data System (ADS)

    Sheppard, Colin J. R.; Mehta, Shalin B.

    2016-03-01

    Imaging in a bright field or phase contrast microscope is partially coherent. We have found that the image can be conveniently considered and modeled in terms of the Wigner distribution function (WDF) of the object transmission. The WDF of the object has a simple physical interpretation for the case of a slowly varying object. Basically, the image intensity is the spatial marginal of the spatial convolution of the object WDF with the phase space imager kernel (PSIkernel), a rotated version of the transmission cross-coefficient. The PSI-kernel can be regarded as a partially-coherent generalization of the point spread function. This approach can be extended to consider the partial coherence of the image itself. In particular, we can consider the mutual intensity, WDF or ambiguity function of the image. It is important to note that the spatial convolution of the object WDF with the PSI-kernel is not a WDF, and not the WDF of the image. The phase space representations of the image have relevance to phase reconstruction methods such as phase space tomography, or the transport of intensity equation approach, and to the three-dimensional image properties.

  14. PHASE DIFFERENTIAL INDICATING CIRCUIT

    DOEpatents

    Kirsten, F.A.

    1962-01-01

    An electronic circuit for totalizing the net phase difference between two alternating current signals is designed which responds to both increasing and decreasing phase changes. A phase comparator provldes an output pulse for each 360 deg of phase difference occurring, there being a negative pulse for phase shtft in one direction and a positive pulse for a phase shift in the opposite direction. A counting circuit utilizing glow discharge tubes receives the negative and positive pulses at a single input terminal and provides a running net total, pulses of one polarity dded and pulses of the opposite polarity being subtracted. The glow discharge tubes may be decaded to increase the total count capacity. (AEC)

  15. Gymnastics in Phase Space

    SciTech Connect

    Chao, Alexander Wu; /SLAC

    2012-03-01

    As accelerator technology advances, the requirements on accelerator beam quality become increasingly demanding. Facing these new demands, the topic of phase space gymnastics is becoming a new focus of accelerator physics R&D. In a phase space gymnastics, the beam's phase space distribution is manipulated and precision tailored to meet the required beam qualities. On the other hand, all realization of such gymnastics will have to obey accelerator physics principles as well as technological limitations. Recent examples of phase space gymnastics include Emittance exchanges, Phase space exchanges, Emittance partitioning, Seeded FELs and Microbunched beams. The emittance related topics of this list are reviewed in this report. The accelerator physics basis, the optics design principles that provide these phase space manipulations, and the possible applications of these gymnastics, are discussed. This fascinating new field promises to be a powerful tool of the future.

  16. Noncommutative Anandan quantum phase

    NASA Astrophysics Data System (ADS)

    Passos, E.; Ribeiro, L. R.; Furtado, C.; Nascimento, J. R.

    2007-07-01

    In this work, we study the noncommutative nonrelativistic quantum dynamics of a neutral particle, which possesses permanent magnetic and electric dipole moments, in the presence of external electric and magnetic fields. We use the Foldy-Wouthuysen transformation of the Dirac spinor with a nonminimal coupling to obtain the nonrelativistic limit. In this limit, we study the noncommutative quantum dynamics and obtain the noncommutative Anandan geometric phase. We analyze the situation where the magnetic dipole moment of the particle is zero, and we obtain the noncommutative version of the He-McKellar-Wilkens effect. We demonstrate that this phase in the noncommutative case is a geometric dispersive phase. We also investigate this geometric phase by considering the noncommutativity in the phase space, and the Anandan phase is obtained.

  17. Crystal phase identification

    DOEpatents

    Michael, Joseph R.; Goehner, Raymond P.; Schlienger, Max E.

    2001-01-01

    A method and apparatus for determining the crystalline phase and crystalline characteristics of a sample. This invention provides a method and apparatus for unambiguously identifying and determining the crystalline phase and crystalline characteristics of a sample by using an electron beam generator, such as a scanning electron microscope, to obtain a backscattered electron Kikuchi pattern of a sample, and extracting crystallographic and composition data that is matched to database information to provide a quick and automatic method to identify crystalline phases.

  18. Phase Holograms In PMMA

    NASA Technical Reports Server (NTRS)

    Maker, Paul D.; Muller, Richard E.

    1994-01-01

    Complex, computer-generated phase holograms written in thin films of poly(methyl methacrylate) (PMMA) by process of electron-beam exposure followed by chemical development. Spatial variations of phase delay in holograms quasi-continuous, as distinquished from stepwise as in binary phase holograms made by integrated-circuit fabrication. Holograms more precise than binary holograms. Greater continuity and precision results in decreased scattering loss and increased imaging efficiency.

  19. Holographic magnetic phase transition

    SciTech Connect

    Lifschytz, Gilad; Lippert, Matthew

    2009-09-15

    We study four-dimensional interacting fermions in a strong magnetic field, using the holographic Sakai-Sugimoto model of intersecting D4- and D8-branes in the deconfined, chiral-symmetric parallel phase. We find that as the magnetic field is varied, while staying in the parallel phase, the fermions exhibit a first-order phase transition in which their magnetization jumps discontinuously. Properties of this transition are consistent with a picture in which some of the fermions jump to the lowest Landau level. Similarities to known magnetic phase transitions are discussed.

  20. Phase Equilibria Diagrams Database

    National Institute of Standards and Technology Data Gateway

    SRD 31 NIST/ACerS Phase Equilibria Diagrams Database (PC database for purchase)   The Phase Equilibria Diagrams Database contains commentaries and more than 21,000 diagrams for non-organic systems, including those published in all 21 hard-copy volumes produced as part of the ACerS-NIST Phase Equilibria Diagrams Program (formerly titled Phase Diagrams for Ceramists): Volumes I through XIV (blue books); Annuals 91, 92, 93; High Tc Superconductors I & II; Zirconium & Zirconia Systems; and Electronic Ceramics I. Materials covered include oxides as well as non-oxide systems such as chalcogenides and pnictides, phosphates, salt systems, and mixed systems of these classes.

  1. Phase detection of chaos.

    PubMed

    Follmann, Rosangela; Macau, Elbert E N; Rosa, Epaminondas

    2011-01-01

    A technique, first introduced in the context of pseudoperiodic sound waves, is here applied to the problem of detecting the phase of phase coherent and also phase noncoherent chaotic oscillators. The approach is based on finding sinusoidal fits to segments of the signal, therefore obtaining, for each segment, an appropriate frequency from which a phase can be derived. Central to the method is a judicious choice for the size of a sliding window and for the frequency range, as well as for the window advancing step. The approach is robust against moderate noise levels and three cases are presented for demonstrating the applicability of the method. PMID:21405762

  2. Phase Contrast Imaging

    SciTech Connect

    Menk, Ralf Hendrik

    2008-11-13

    All standard (medical) x-ray imaging technologies, rely primarily on the amplitude properties of the incident radiation, and do not depend on its phase. This is unchanged since the discovery by Roentgen that the intensity of an x-ray beam, as measured by the exposure on a film, was related to the relative transmission properties of an object. However, recently various imaging techniques have emerged which depend on the phase of the x-rays as well as the amplitude. Phase becomes important when the beam is coherent and the imaging system is sensitive to interference phenomena. Significant new advances have been made in coherent optic theory and techniques, which now promise phase information in medical imaging. The development of perfect crystal optics and the increasing availability of synchrotron radiation facilities have contributed to a significant increase in the application of phase based imaging in materials and life sciences. Unique source characteristics such as high intensity, monochromaticity, coherence and high collimating provide an ideal source for advanced imaging. Phase contrast imaging has been applied in both projection and computed tomography modes, and recent applications have been made in the field of medical imaging. Due to the underlying principle of X-ray detection conventional image receptors register only intensities of wave fields and not their phases. During the last decade basically five different methods were developed that translate the phase information into intensity variations. These methods are based on measuring the phase shift {phi} directly (using interference phenomena), the gradient {nabla}{sub {phi}}, or the Laplacian {nabla}{sup 2}{phi}. All three methods can be applied to polychromatic X-ray sources keeping in mind that the native source is synchrotron radiation, featuring monochromatic and reasonable coherent X-ray beams. Due to the vast difference in the coefficients that are driven absorption and phase effects (factor 1

  3. LIGHT NONAQUEOUS PHASE LIQUIDS

    EPA Science Inventory

    Nonaqueous phase liquids (NAPLS) are hydrocarbons that exist as a separate, immiscible phase when in contact with water and/or air. ifferences in the physical and chemical properties of water and NAPL result in the formation of a physical interface between the liquids which preve...

  4. Templated blue phases.

    PubMed

    Ravnik, Miha; Fukuda, Jun-ichi

    2015-11-21

    Cholesteric blue phases of a chiral liquid crystal are interesting examples of self-organised three-dimensional nanostructures formed by soft matter. Recently it was demonstrated that a polymer matrix introduced by photopolymerization inside a bulk blue phase not only stabilises the host blue phase significantly, but also serves as a template for blue phase ordering. We show with numerical modelling that the transfer of the orientational order of the blue phase to the surfaces of the polymer matrix, together with the resulting surface anchoring, can account for the templating behaviour of the polymer matrix inducing the blue phase ordering of an achiral nematic liquid crystal. Furthermore, tailoring the anchoring conditions of the polymer matrix surfaces can bring about orientational ordering different from those of bulk blue phases, including an intertwined complex of the polymer matrix and topological line defects of orientational order. Optical Kerr response of templated blue phases is explored, finding large Kerr constants in the range of K = 2-10 × 10(-9) m V(-2) and notable dependence on the surface anchoring strength. More generally, the presented numerical approach is aimed to clarify the role and actions of templating polymer matrices in complex chiral nematic fluids, and further to help design novel template-based materials from chiral liquid crystals. PMID:26412643

  5. Demonstrating Phase Changes.

    ERIC Educational Resources Information Center

    Rohr, Walter

    1995-01-01

    Presents two experiments that demonstrate phase changes. The first experiment explores phase changes of carbon dioxide using powdered dry ice sealed in a piece of clear plastic tubing. The second experiment demonstrates an equilibrium process in which a crystal grows in equilibrium with its saturated solution. (PVD)

  6. Simulation of phase structures

    SciTech Connect

    Lawson, J.

    1995-04-20

    This memo outlines a procedure developed by the author to extract information from phase measurements and produce a simulated phase structure for use in modeling optical systems, including characteristic optics for the Beamlet and NIF laser systems. The report includes an IDL program listing.

  7. Lunar Phases Planisphere

    ERIC Educational Resources Information Center

    Shawl, Stephen J.

    2010-01-01

    This paper describes a lunar phases planisphere with which a user can answer questions about the rising and setting times of the Moon as well as questions about where the Moon will be at a given phase and time. The article contains figures that can be photocopied to make the planisphere. (Contains 2 figures.)

  8. UPVG phase 2 report

    SciTech Connect

    1995-08-01

    The Utility PhotoVoltaic Group (UPVG), supported by member dues and a grant from the US Department of Energy, has as its mission the acceleration of the use of cost-effective small-scale and emerging large-scale applications of photovoltaics for the benefit of electric utilities and their customers. Formed in October, 1992, with the support of the American Public Power Association, Edison Electric Institute, and the National Rural Electric Cooperative Association, the UPVG currently has 90 members from all sectors of the electric utility industry. The UPVG`s efforts as conceived were divided into four phases: Phase 0--program plan; Phase 1--organization and strategy development; Phase 2--creating market assurance; and Phase 3--higher volume purchases. The Phase 0 effort developed the program plan and was completed early in 1993. The Phase 1 goal was to develop the necessary background information and analysis to lead to a decision as to which strategies could be undertaken by utilities to promote greater understanding of PV markets and achieve increased volumes of PV purchases. This report provides the details of the UPVG`s Phase 2 efforts to initiate TEAM-UP, its multiyear, 50-MW hardware initiative.

  9. Low distortion automatic phase control circuit. [voltage controlled phase shifter

    NASA Technical Reports Server (NTRS)

    Hauge, G.; Pederson, C. W. (Inventor)

    1974-01-01

    A voltage controlled phase shifter is rendered substantially harmonic distortion free over a large dynamic input range by employing two oppositely poled, equally biased varactor diodes as the voltage controlled elements which adjust the phase shift. Control voltages which affect the bias of both diodes equally are used to adjust the phase shift without increasing distortion. A feedback stabilized phase shifter is rendered substantially frequency independent by employing a phase detector to control the phase shift of the voltage controlled phase shifter.

  10. Source Wavelet Phase Extraction

    NASA Astrophysics Data System (ADS)

    Naghadeh, Diako Hariri; Morley, Christopher Keith

    2016-06-01

    Extraction of propagation wavelet phase from seismic data can be conducted using first, second, third and fourth-order statistics. Three new methods are introduced, which are: (1) Combination of different moments, (2) Windowed continuous wavelet transform and (3) Maximum correlation with cosine function. To compare different methods synthetic data with and without noise were chosen. Results show that first, second and third order statistics are not able to preserve wavelet phase. Kurtosis can preserve propagation wavelet phase but signal-to-noise ratio can affect the extracted phase using this method. So for data set with low signal-to-noise ratio, it will be unstable. Using a combination of different moments to extract the phase is more robust than applying kurtosis. The improvement occurs because zero phase wavelets with reverse polarities have equal maximum kurtosis values hence the correct wavelet polarity cannot be identified. Zero-phase wavelets with reverse polarities have minimum and maximum values for a combination of different-moments method. These properties enable the technique to handle a finite data segment and to choose the correct wavelet polarity. Also, the existence of different moments can decrease sensitivity to outliers. A windowed continuous wavelet transform is more sensitive to signal-to-noise ratio than the combination of different-moments method, also if the scale for the wavelet is incorrect it will encounter with more problems to extract phase. When the effects of frequency bandwidth, signal-to-noise ratio and analyzing window length are considered, the results of extracting phase information from data without and with noise demonstrate that combination of different-moments is superior to the other methods introduced here.

  11. Gas Phase Nanoparticle Synthesis

    NASA Astrophysics Data System (ADS)

    Granqvist, Claes; Kish, Laszlo; Marlow, William

    This book deals with gas-phase nanoparticle synthesis and is intended for researchers and research students in nanomaterials science and engineering, condensed matter physics and chemistry, and aerosol science. Gas-phase nanoparticle synthesis is instrumental to nanotechnology - a field in current focus that raises hopes for environmentally benign, resource-lean manufacturing. Nanoparticles can be produced by many physical, chemical, and even biological routes. Gas-phase synthesis is particularly interesting since one can achieve accurate manufacturing control and hence industrial viability.

  12. Microfluidic binary phase flow

    NASA Astrophysics Data System (ADS)

    Angelescu, Dan; Menetrier, Laure; Wong, Joyce; Tabeling, Patrick; Salamitou, Philippe

    2004-03-01

    We present a novel binary phase flow regime where the two phases differ substantially in both their wetting and viscous properties. Optical tracking particles are used in order to investigate the details of such multiphase flow inside capillary channels. We also describe microfluidic filters we have developed, capable of separating the two phases based on capillary pressure. The performance of the filters in separating oil-water emulsions is discussed. Binary phase flow has been previously used in microchannels in applications such as emulsion generation, enhancement of mixing and assembly of custom colloidal paticles. Such microfluidic systems are increasingly used in a number of applications spanning a diverse range of industries, such as biotech, pharmaceuticals and more recently the oil industry.

  13. FEL phased array configurations

    NASA Astrophysics Data System (ADS)

    Shellan, Jeffrey B.

    1986-01-01

    The advantages and disadvantages of various phased array and shared aperture concepts for FEL configurations are discussed. Consideration is given to the characteristics of intra- and inter-micropulse phasing; intra-macropulse phasing; an internal coupled resonator configuration; and an injection locked oscillator array. The use of a master oscillator power amplifier (MOPA) configuration with multiple or single master oscillators for FELs is examined. The venetian blind, rotating plate, single grating, and grating rhomb shared aperture concepts are analyzed. It is noted that the shared aperture approach using a grating rhomb and the MOPA concept with a single master oscillator and a coupled resonator are useful for FEL phased array configurations; and the MOPA concept is most applicable.

  14. Coaxial phased array antenna

    NASA Astrophysics Data System (ADS)

    Ellis, H., Jr.

    1980-08-01

    A coaxial antenna array for communicating circularly polarized electromagnetic radiation is disclosed. A pair of open ended antenna cavities is coaxially constructed and operates by excitation of linear radiation elements arranged within each of the cavities. A pair of crossed dipole radiation devices is centered within the inner cavity and operated by means of a phase shifting network circuit to transmit as well as receive circularly polarized radiation. Four monopole radiation devices are symmetrically arranged to operate in the outer cavity in phase quadrature by means of the phase shifting network circuit to both transmit and receive circularly polarized electromagnetic radiation. Combined operation of the two antenna cavities with a 180 deg phase differential between the fields related to the two antenna cavities provides a broad beam, relatively wide frequency bandwidth communication capability. Particular embodiments disclosed feature a generally square cavity array as well as a circular cavity array.

  15. Coaxial phased array antenna

    NASA Technical Reports Server (NTRS)

    Ellis, H., Jr. (Inventor)

    1980-01-01

    A coaxial antenna array for communicating circularly polarized electromagnetic radiation is disclosed. A pair of open ended antenna cavities is coaxially constructed and operates by excitation of linear radiation elements arranged within each of the cavities. A pair of crossed dipole radiation devices is centered within the inner cavity and operated by means of a phase shifting network circuit to transmit as well as receive circularly polarized radiation. Four monopole radiation devices are symmetrically arranged to operate in the outer cavity in phase quadrature by means of the phase shifting network circuit to both transmit and receive circularly polarized electromagnetic radiation. Combined operation of the two antenna cavities with a 180 deg phase differential between the fields related to the two antenna cavities provides a broad beam, relatively wide frequency bandwidth communication capability. Particular embodiments disclosed feature a generally square cavity array as well as a circular cavity array.

  16. ELECTRONIC PHASE CONTROL CIRCUIT

    DOEpatents

    Salisbury, J.D.; Klein, W.W.; Hansen, C.F.

    1959-04-21

    An electronic circuit is described for controlling the phase of radio frequency energy applied to a multicavity linear accelerator. In one application of the circuit two cavities are excited from a single radio frequency source, with one cavity directly coupled to the source and the other cavity coupled through a delay line of special construction. A phase detector provides a bipolar d-c output signal proportional to the difference in phase between the voltage in the two cavities. This d-c signal controls a bias supply which provides a d-c output for varying the capacitnce of voltage sensitive capacitors in the delay line. The over-all operation of the circuit is completely electronic, overcoming the time response limitations of the electromechanical control systems, and the relative phase relationship of the radio frequency voltages in the two caviiies is continuously controlled to effect particle acceleration.

  17. Geometry and Moon Phases.

    ERIC Educational Resources Information Center

    Thompson, Kenneth W.; Harrell, Marvin E.

    1997-01-01

    Describes an activity, designed to comply with the National Science Education Standards, that integrates science and mathematics concepts. Mathematical modeling of the moon's phases is employed to show students the role of mathematics in describing scientific phenomena. (DKM)

  18. Digital Receiver Phase Meter

    NASA Technical Reports Server (NTRS)

    Marcin, Martin; Abramovici, Alexander

    2008-01-01

    The software of a commercially available digital radio receiver has been modified to make the receiver function as a two-channel low-noise phase meter. This phase meter is a prototype in the continuing development of a phase meter for a system in which radiofrequency (RF) signals in the two channels would be outputs of a spaceborne heterodyne laser interferometer for detecting gravitational waves. The frequencies of the signals could include a common Doppler-shift component of as much as 15 MHz. The phase meter is required to measure the relative phases of the signals in the two channels at a sampling rate of 10 Hz at a root power spectral density <5 microcycle/(Hz)1/2 and to be capable of determining the power spectral density of the phase difference over the frequency range from 1 mHz to 1 Hz. Such a phase meter could also be used on Earth to perform similar measurements in laser metrology of moving bodies. To illustrate part of the principle of operation of the phase meter, the figure includes a simplified block diagram of a basic singlechannel digital receiver. The input RF signal is first fed to the input terminal of an analog-to-digital converter (ADC). To prevent aliasing errors in the ADC, the sampling rate must be at least twice the input signal frequency. The sampling rate of the ADC is governed by a sampling clock, which also drives a digital local oscillator (DLO), which is a direct digital frequency synthesizer. The DLO produces samples of sine and cosine signals at a programmed tuning frequency. The sine and cosine samples are mixed with (that is, multiplied by) the samples from the ADC, then low-pass filtered to obtain in-phase (I) and quadrature (Q) signal components. A digital signal processor (DSP) computes the ratio between the Q and I components, computes the phase of the RF signal (relative to that of the DLO signal) as the arctangent of this ratio, and then averages successive such phase values over a time interval specified by the user.

  19. Production of Liquid Alkanes by Aqueous-Phase Processing of Biomass-Derived Carbohydrates

    NASA Astrophysics Data System (ADS)

    Huber, George W.; Chheda, Juben N.; Barrett, Christopher J.; Dumesic, James A.

    2005-06-01

    Liquid alkanes with the number of carbon atoms ranging from C7 to C15 were selectively produced from biomass-derived carbohydrates by acid-catalyzed dehydration, which was followed by aldol condensation over solid base catalysts to form large organic compounds. These molecules were then converted into alkanes by dehydration/hydrogenation over bifunctional catalysts that contained acid and metal sites in a four-phase reactor, in which the aqueous organic reactant becomes more hydrophobic and a hexadecane alkane stream removes hydrophobic species from the catalyst before they go on further to form coke. These liquid alkanes are of the appropriate molecular weight to be used as transportation fuel components, and they contain 90% of the energy of the carbohydrate and H2 feeds.

  20. Efficient Bayesian Phase Estimation

    NASA Astrophysics Data System (ADS)

    Wiebe, Nathan; Granade, Chris

    2016-07-01

    We introduce a new method called rejection filtering that we use to perform adaptive Bayesian phase estimation. Our approach has several advantages: it is classically efficient, easy to implement, achieves Heisenberg limited scaling, resists depolarizing noise, tracks time-dependent eigenstates, recovers from failures, and can be run on a field programmable gate array. It also outperforms existing iterative phase estimation algorithms such as Kitaev's method.

  1. Efficient Bayesian Phase Estimation.

    PubMed

    Wiebe, Nathan; Granade, Chris

    2016-07-01

    We introduce a new method called rejection filtering that we use to perform adaptive Bayesian phase estimation. Our approach has several advantages: it is classically efficient, easy to implement, achieves Heisenberg limited scaling, resists depolarizing noise, tracks time-dependent eigenstates, recovers from failures, and can be run on a field programmable gate array. It also outperforms existing iterative phase estimation algorithms such as Kitaev's method. PMID:27419551

  2. Phased array antenna control

    NASA Technical Reports Server (NTRS)

    Doland, G. D. (Inventor)

    1978-01-01

    Several new and useful improvements in steering and control of phased array antennas having a small number of elements, typically on the order of 5 to 17 elements are provided. Among the improvements are increasing the number of beam steering positions, reducing the possibility of phase transients in signals received or transmitted with the antennas, and increasing control and testing capacity with respect to the antennas.

  3. Electron microscope phase enhancement

    DOEpatents

    Jin, Jian; Glaeser, Robert M.

    2010-06-15

    A microfabricated electron phase shift element is used for modifying the phase characteristics of an electron beam passing though its center aperture, while not affecting the more divergent portion of an incident beam to selectively provide a ninety-degree phase shift to the unscattered beam in the back focal plan of the objective lens, in order to realize Zernike-type, in-focus phase contrast in an electron microscope. One application of the element is to increase the contrast of an electron microscope for viewing weakly scattering samples while in focus. Typical weakly scattering samples include biological samples such as macromolecules, or perhaps cells. Preliminary experimental images demonstrate that these devices do apply a ninety degree phase shift as expected. Electrostatic calculations have been used to determine that fringing fields in the region of the scattered electron beams will cause a negligible phase shift as long as the ratio of electrode length to the transverse feature-size aperture is about 5:1. Calculations are underway to determine the feasibility of aspect smaller aspect ratios of about 3:1 and about 2:1.

  4. Quantum phase of inflation

    NASA Astrophysics Data System (ADS)

    Berera, Arjun; Rangarajan, Raghavan

    2013-02-01

    Inflation models can have an early phase of inflation where the evolution of the inflaton is driven by quantum fluctuations before entering the phase driven by the slope of the scalar field potential. For a Coleman-Weinberg potential this quantum phase lasts 107-8 e-foldings. A long period of fluctuation driven growth of the inflation field can possibly take the inflaton past ϕ*, the value of the field where our current horizon scale crosses the horizon; alternatively, even if the field does not cross ϕ*, the inflaton could have high kinetic energy at the end of this phase. Therefore, we study these issues in the context of different models of inflation. In scenarios where cosmological relevant scales leave during the quantum phase, we obtain large curvature perturbations of O(10). We also apply our results to quadratic curvaton models and to quintessence models. In curvaton models we find that inflation must last longer than required to solve the horizon problem, that the curvaton models are incompatible with small field inflation models, and that there may be too large non-Gaussianity. A new phase of thermal fluctuation driven inflation is proposed, in which during inflation the inflaton evolution is governed by fluctuations from a sustained thermal radiation bath rather than by a scalar field potential.

  5. Electron Holography: phases matter.

    PubMed

    Lichte, Hannes

    2013-06-01

    Essentially, all optics is wave optics, be it with light, X-rays, neutrons or electrons. The information transfer from the object to the image can only be understood in terms of waves given by amplitude and phase. However, phases are difficult to measure: for slowly oscillating waves such as sound or low-frequency electromagnetic waves, phases can be measured directly; for high frequencies this has to be done by heterodyne detection, i.e. superposition with a reference and averaging over time. In optics, this is called interferometry. Because interference is mostly very difficult to achieve, phases have often been considered 'hidden variables' seemingly pulling the strings from backstage, only visible by their action on the image intensity. This was almost the case in conventional Electron Microscopy with the phase differences introduced by an object. However, in the face of the urgent questions from solid state physics and materials science, these phases have to be determined precisely, because they encode the most dominant object properties, such as charge distributions and electromagnetic fields. After more than six decades of very patient advancement, electron interferometry and holography offer unprecedented analytical facilities down to an atomic scale. Akira Tonomura has prominently contributed to the present state. PMID:23620338

  6. Compressed sensing phase retrieval with phase diversity

    NASA Astrophysics Data System (ADS)

    Qin, Shun; Hu, Xinqi; Qin, Qiong

    2014-01-01

    The compressed sensing (CS) theory shows that sparse signal can be reconstructed accurately with some randomly observed measurements that are much fewer than what traditional method requires. Since it takes structure of signals into consideration, it has many advantages in the structured signals process. With CS, measuring can be speeded up and the cost of hardware can be decreased significantly. However, it faces great challenge in the amplitude-only measurement. In this article, we study the magnitude-only compressed sensing phase retrieval (CSPR) problem, and propose a practical recovery algorithm. In our algorithm, we introduce the powerful Hybrid-Input-Output algorithm with phase diversity to make our algorithm robust and efficient. A relaxed ℓ0 norm constrain is also introduced to help PR find a sparse solution with fewer measurements, which is demonstrated to be essential and effective to CSPR. We finally successfully apply it into complex-valued object recovery in THz imaging. The numerical results show that the proposed algorithm can recover the object pretty well with fewer measurements than what PR traditionally requires.

  7. Phased array ghost elimination.

    PubMed

    Kellman, Peter; McVeigh, Elliot R

    2006-05-01

    Parallel imaging may be applied to cancel ghosts caused by a variety of distortion mechanisms, including distortions such as off-resonance or local flow, which are space variant. Phased array combining coefficients may be calculated that null ghost artifacts at known locations based on a constrained optimization, which optimizes SNR subject to the nulling constraint. The resultant phased array ghost elimination (PAGE) technique is similar to the method known as sensitivity encoding (SENSE) used for accelerated imaging; however, in this formulation is applied to full field-of-view (FOV) images. The phased array method for ghost elimination may result in greater flexibility in designing acquisition strategies. For example, in multi-shot EPI applications ghosts are typically mitigated by the use of an interleaved phase encode acquisition order. An alternative strategy is to use a sequential, non-interleaved phase encode order and cancel the resultant ghosts using PAGE parallel imaging. Cancellation of ghosts by means of phased array processing makes sequential, non-interleaved phase encode acquisition order practical, and permits a reduction in repetition time, TR, by eliminating the need for echo-shifting. Sequential, non-interleaved phase encode order has benefits of reduced distortion due to off-resonance, in-plane flow and EPI delay misalignment. Furthermore, the use of EPI with PAGE has inherent fat-water separation and has been used to provide off-resonance correction using a technique referred to as lipid elimination with an echo-shifting N/2-ghost acquisition (LEENA), and may further generalized using the multi-point Dixon method. Other applications of PAGE include cancelling ghosts which arise due to amplitude or phase variation during the approach to steady state. Parallel imaging requires estimates of the complex coil sensitivities. In vivo estimates may be derived by temporally varying the phase encode ordering to obtain a full k-space dataset in a scheme

  8. Combustion 2000: Phase II

    SciTech Connect

    Unknown

    1999-11-01

    The goals of the program are to develop a coal-fired high performance power generation system (HIPPS) that is capable of: thermal efficiency (HHV) {ge} 47%; NOx, SOx, and particulates {le} 10% NSPS (New Source Performance Standard); coal providing {ge} 65% of heat input; all solid wastes benign; and cost of electricity {le} 90% of present plants. Phase 1, which began in 1992, focused on the analysis of various configurations of indirectly fired cycles and on technical assessments of alternative plant subsystems and components, including performance requirements, developmental status, design options, complexity and reliability, and capital and operating costs. Phase 1 also included preliminary R and D and the preparation of designs for HIPPS commercial plants approximately 300 MWe in size. This Phase, Phase 2, had as its initial objective the development of a complete design base for the construction and operation of a HIPPS prototype plant to be constructed in Phase 3. As part of a descoping initiative, the Phase 3 program has been eliminated and work related to the commercial plant design has been ended. The rescoped program retained a program of engineering research and development focusing on high temperature heat exchangers, e.g. HITAF development (Task 2); a rescoped Task 6 that is pertinent to Vision 21 objectives and focuses on advanced cycle analysis and optimization, integration of gas turbines into complex cycles, and repowering designs; and preparation of the Phase 2 Technical Report (Task 8). This rescoped program deleted all subsystem testing (Tasks 3, 4,and 5) and the development of a site-specific engineering design and test plan for the HIPPS prototype plant (Task 7). Work reported herein is from: Task 2.1 HITAF Combustors; Task 2.2 HITAF Air Heaters; and Task 6 HIPPS Commercial Plant Design Update.

  9. The NMR phased array.

    PubMed

    Roemer, P B; Edelstein, W A; Hayes, C E; Souza, S P; Mueller, O M

    1990-11-01

    We describe methods for simultaneously acquiring and subsequently combining data from a multitude of closely positioned NMR receiving coils. The approach is conceptually similar to phased array radar and ultrasound and hence we call our techniques the "NMR phased array." The NMR phased array offers the signal-to-noise ratio (SNR) and resolution of a small surface coil over fields-of-view (FOV) normally associated with body imaging with no increase in imaging time. The NMR phased array can be applied to both imaging and spectroscopy for all pulse sequences. The problematic interactions among nearby surface coils is eliminated (a) by overlapping adjacent coils to give zero mutual inductance, hence zero interaction, and (b) by attaching low input impedance preamplifiers to all coils, thus eliminating interference among next nearest and more distant neighbors. We derive an algorithm for combining the data from the phased array elements to yield an image with optimum SNR. Other techniques which are easier to implement at the cost of lower SNR are explored. Phased array imaging is demonstrated with high resolution (512 x 512, 48-cm FOV, and 32-cm FOV) spin-echo images of the thoracic and lumbar spine. Data were acquired from four-element linear spine arrays, the first made of 12-cm square coils and the second made of 8-cm square coils. When compared with images from a single 15 x 30-cm rectangular coil and identical imaging parameters, the phased array yields a 2X and 3X higher SNR at the depth of the spine (approximately 7 cm). PMID:2266841

  10. On phase reconstruction

    NASA Astrophysics Data System (ADS)

    Lee, Chung-Min

    This thesis focuses on the mathematical analysis of the optical phase reconstruction problem. Phase information of light waves has played an important role in many optical applications. However, the phase function of a light wave cannot be measured directly. In 1983, Teague proposed the idea of an intensity senor for measuring phase functions of light waves. It uses an elliptic partial differential equation called the Transport of Intensity Equation (TIE), which relates intensity to the phase function of a light wave. Teague's study was followed by Roddier and others. When intensity decreases to zero at the boundary, the equation has singularity since the diffusion coefficient vanishes. In 1996, Gureyev and Nugent claimed that no boundary conditions are needed for getting a unique solution of the TIE in this singular case. We present in this thesis the theoretical analysis of the necessity of boundary conditions for solving the TIE. A hybrid theoretical-numerical boundary condition is also derived for solving the TIE numerically in the case of vanishing intensity at the boundary. Numerical tests and optical simulations over discs verified the potency of this theoretical-numerical hybrid boundary condition and the algorithm. Another approach studied is the Weighted Least Action Principle (WLAP), which is proposed by Rubinstein and Wolansky in the year 2004. The WLAP states a variational principle for finding the light rays mapping between two planes using the intensity profiles on the planes, and it writes the problem of phase reconstruction in the functional form. Minimizing the associated functional, we obtain the ray mapping of the light wave in question. The phase function can be derived from the optimized ray mapping. A numerical algorithm was designed to carry out the process. Simulations and tests are reported to show the feasibility of the methods proposed.

  11. Separation of dialkyl sulfides by metallo-mesogenic stationary phases for complexation gas chromatography.

    PubMed

    Chen, Jian-Lian; Liu, Chuen-Ying

    2007-08-17

    A copper mesogenic side-chain polymer (P-C(15)CuC(18)) was cross-linked onto the capillary wall as a stationary film for gas chromatography (GC) separation of alkyl sulfides. These organic sulfides are of interest for their large health impact because of their wide range of volatiles and high reactivities toward metals. Different GC parameters for optimal separation efficiency are discussed for use with a mesogenic polymer column along with flame photometric detection (FPD). Both the carrier gas flow-rate and column temperature were studied to determine the relationship of plate height to the chemical structure of the solutes, as well as to determine the morphology of the mesogenic polymer. Van 't Hoff plots show phase transitions of the stationary mesophase as the column temperature was varied. The results reveal that the separation mechanism might be based on ligand exchange and polarity interaction between the analytes and the stationary phase, with the vapor pressure of the analytes also being important. The former interaction dominates in the lamellar crystalline phase and the latter interaction dominates in the hexagonal columnar-discotic phase. With high reproducibility for retention time (RSD< or =0.37%) and for peak area (RSD< or =5.16%), the GC-FPD system produced linear calibration graphs (r> or =0.9918) for the determination of 13 sulfides with a detection limit below 2.5 ng. PMID:17568598

  12. Digital phase-lock loop

    NASA Technical Reports Server (NTRS)

    Thomas, Jr., Jess B. (Inventor)

    1991-01-01

    An improved digital phase lock loop incorporates several distinctive features that attain better performance at high loop gain and better phase accuracy. These features include: phase feedback to a number-controlled oscillator in addition to phase rate; analytical tracking of phase (both integer and fractional cycles); an amplitude-insensitive phase extractor; a more accurate method for extracting measured phase; a method for changing loop gain during a track without loss of lock; and a method for avoiding loss of sampled data during computation delay, while maintaining excellent tracking performance. The advantages of using phase and phase-rate feedback are demonstrated by comparing performance with that of rate-only feedback. Extraction of phase by the method of modeling provides accurate phase measurements even when the number-controlled oscillator phase is discontinuously updated.

  13. EUCLIDES: first phase completed!

    NASA Astrophysics Data System (ADS)

    Benschop, Jos P.; Dinger, Udo; Ockwell, David C.

    2000-07-01

    The Extreme UV Concept Lithography Development System (EUCLIDES) program headed by ASM Lithography (ASML), partnered with Carl Zeiss and Oxford Instruments is evaluating EUV lithography for its viability at resolutions of 70 nm and below. From August 1998 through February 2000 the first phase was done. In this phase, the core technologies necessary to demonstrate the technical solutions for the list of possible EUV lithography 'showstoppers' have been developed. This includes: (1) Mirror substrates, (2) High reflectivity multi- layer coatings, (3) Resist outgassing reduction schemes, (4) Vacuum stages. A synchrotron source design was developed to compare synchrotron sources with plasma sources. The consortium also investigated the total system architecture to make sure the system concept meets the requirements of the semiconductor industry at an acceptable cost of ownership. In this paper, an overview of the program objectives is given, followed by an overview of highlights obtained by the various program partners and subcontractors throughout the first phase. Finally, the European partner's plan for the next phase is shown (working in close collaboration with other international consortia). This next phase will eventually lead to EUVL production tools.

  14. Phasing rectangular apertures.

    PubMed

    Baker, K L; Homoelle, D; Utterback, E; Jones, S M

    2009-10-26

    Several techniques have been developed to phase apertures in the context of astronomical telescopes with segmented mirrors. Phasing multiple apertures, however, is important in a wide range of optical applications. The application of primary interest in this paper is the phasing of multiple short pulse laser beams for fast ignition fusion experiments. In this paper analytic expressions are derived for parameters such as the far-field distribution, a line-integrated form of the far-field distribution that could be fit to measured data, enclosed energy or energy-in-a-bucket and center-of-mass that can then be used to phase two rectangular apertures. Experimental data is taken with a MEMS device to simulate the two apertures and comparisons are made between the analytic parameters and those derived from the measurements. Two methods, fitting the measured far-field distribution to the theoretical distribution and measuring the ensquared energy in the far-field, produced overall phase variance between the 100 measurements of less than 0.005 rad(2) or an RMS displacement of less than 12 nm. PMID:19997175

  15. Two-phase flow

    NASA Technical Reports Server (NTRS)

    Tacina, Robert R.

    1986-01-01

    An experimental program to characterize the spray from candidate nozzles for icing-cloud simulation is discussed. One canidate nozzle, which is currently used for icing research, has been characterized for flow and drop size. The median-volume diameter (MVD) from this air-assist nozzle is compared with correlations in the literature. The new experimental spray facility is discussed, and the drop-size instruments are discussed in detail. Since there is no absolute standard for drop-size measurements and there are other limitations, such as drop -size range and velocity range, several instruments are used and results are compared. A two-phase model was developed at Pennsylvania State University. The model uses the k-epsilon model of turbulence in the continous phase. Three methods for treating the discrete phase are used: (1) a locally homogeneous flow (LHF) model, (2) a deterministic separated flow (DSF) model, and (3) a stochastic separated flow (SSF) model. In the LHF model both phases have the same velocity and temperature at each point. The DSF model provides interphase transport but ignores the effects of turbulent fluctuations. In the SSF model the drops interact with turbulent eddies whose properties are determined by the k-epsilon turbulence model. The two-phase flow model has been extended to include the effects of evaporation and combustion.

  16. Single-phase to three-phase power conversion interface

    NASA Astrophysics Data System (ADS)

    Wu, Jinn-Chang; Wang, Yung-Shan; Jou, Hurng-Liahng; Lu, Wei-Tso

    2016-07-01

    This study proposes a single-phase to three-phase power conversion interface which converts the power from a single-phase utility to three-phase power for a three-phase load. The proposed single-phase to three-phase power conversion interface comprises a bridge-type switch set, a set of three-phase inductors, a transformer set and a set of three-phase capacitors. A current-mode control controls the switching of bridge-type switch set, to generate a set of nonzero-sequence (NZS) currents and a set of zero-sequence (ZS) currents. The transformer set is used to decouple the NZS currents and the ZS currents. The NZS currents are used to generate a high-quality three-phase voltage that supplies power to a three-phase load. The ZS currents flow to the single-phase utility so that the utility current is sinusoidal and in phase with the utility voltage. Accordingly, only a bridge-type switch set is used in the single-phase to three-phase power conversion interface to simply the power circuit. A prototype is developed and tested to verify the performance of the proposed single-phase to three-phase power conversion interface.

  17. Short-Range Order of Mesomorphic Phase of a Semi-crystalline Polymer by Solid-State NMR: Isotactic Polypropylene

    NASA Astrophysics Data System (ADS)

    Yuan, Shichen; Miyoshi, Toshikazu

    2015-03-01

    Mesophase is intermediate phase between crystalline and melt state. Characterization of short-range structures of disordered mesomorphic phase without long-range order is challenging issue in polymer characterization. The short range order was considered same as α or β i PP, or neither. In this work, a new strategy using 13C-13C through space interactions as well as molecular dynamics based on chemical shift anisotropy (CSA) re-orientation is proposed for evaluating short-range order of mesophase of isotactic-polypropylene (iPP). 13C-13C double quantum (DQ) build up curves of 13C 15 percent CH3 selectively labeled iPP and spin dynamics simulations elucidate that local packing structures in mesophase is very close to that in β phase. Moreover, exchange NMR proves that the crystalline chains perform large amplitude motions in all α, β, and mesophase. The correlation time of overall dynamics of stems in mesophase follows the same Arrhenius line with that of β phase but is largely deviated from the Arrhenius line of the α phase. Through the obtained results, it is concluded that short-range order in mesophase is exceedingly close or same to those in β phase. This work was financially supported by the National Science Foundation (Grant No. DMR-1105829) and by UA startup funds.

  18. Phase trombones with bending

    SciTech Connect

    Courant, E.D.; Garren, A.

    1985-10-01

    The phase shifting trombones considered up to now for SSC application consisted of sets of evenly spaced quadrupoles separated by drift spaces. One such trombone was placed between a dispersion suppressor and a crossing insertion, so that the trombone had zero dispersion. With such trombones, it is possible to change {beta}{sup *} at constant tune, or to change the tunes by several units without altering the cell phase advances in the arcs. An objection to the above type of phase trombone is that it adds to the circumference, since no bending is included. This objection may or may not be valid depending on the potential usefulness of the drift spaces in them. In this note the authors show an alternative trombone design in which dipoles are included between the quadrupoles as in the normal arc cells. Since these trombones have dispersion, they are placed at the ends of the arcs, to be followed in turn by the dispersion suppressors and crossing insertions.

  19. Controllable tomography phase microscopy

    NASA Astrophysics Data System (ADS)

    Xiu, Peng; Zhou, Xin; Kuang, Cuifang; Xu, Yingke; Liu, Xu

    2015-03-01

    Tomography phase microscopy (TPM) is a new microscopic method that can quantitatively yield the volumetric 3D distribution of a sample's refractive index (RI), which is significant for cell biology research. In this paper, a controllable TPM system is introduced. In this system a circulatory phase-shifting method and piezoelectric ceramic are used which enable the TPM system to record the 3D RI distribution at a more controllable speed, from 1 to 40 fps, than in the other TPM systems reported. The resolution of the RI distribution obtained by this controllable TPM is much better than that in images recorded by phase contrast microscopy and interference tomography microscopy. The realization of controllable TPM not only allows for the application of TPM to the measurement of kinds of RI sample, but also contributes to academic and technological support for the practical use of TPM.

  20. Phase insensitive acoustoelectric transducer

    NASA Technical Reports Server (NTRS)

    Heyman, J. S.

    1978-01-01

    Conventional ultrasonic transducers transform acoustic waves into electrical signals preserving phase and amplitude information. When the acoustic wavelength is significantly smaller than the transducer diameter, severe phase modulation of the electrical signal can occur. This results in anomalous attenuation measurements, background noise in nondestructive evaluation, and in general complicates data interpretation. This article describes and evaluates a phase-insensitive transducer based on the acoustoelectric effect. Theory of operation of the acoustoelectric transducer (AET) is discussed, and some optimization procedures outlined for its use. Directivity data for the AET are contrasted with a conventional piezoelectric transducer. In addition, transmission scanning data of phantom flaws in metal plates are presented for both transducers and demonstrate a significant improvement in resolution with the AET.

  1. Electroweak Phase Transitions

    NASA Astrophysics Data System (ADS)

    Anderson, Gregory Wayne

    An analytic treatment of the one Higgs doublet, electroweak phase transition is given. The phase transition is first order, occurs by the nucleation of thin walled bubbles, and completes at a temperature where the order parameter, _ {T}, is significantly smaller than it is when the origin becomes absolutely unstable. The rate of anomalous baryon number violation is an exponentially sensitive function of T. In very minimal extensions of the standard model it is quite easy to increase T so that anomalous baryon number violation is suppressed after completion of the phase transition. Hence baryogenesis at the electroweak phase transition is tenable in minimal extensions of the standard model. In some cases additional phase transitions are possible. For a light Higgs boson, when the top quark mass is sufficiently large, the state where the Higgs field has a vacuum expectation value = 246 GeV is not the true minimum of the Higgs potential. When this is the case, and when the top quark mass exceeds some critical value, thermal fluctuations in the early universe would have rendered the state = 246 GeV unstable. The requirement that the state = 246 GeV is sufficiently long lived constrains the masses of the Higgs boson and the top quark. Finally, we consider whether local phase transitions can be induced by heavy particles which act as seeds for deformations in the scalar field. Semi-classical reasoning suggests that, when a particle receives a contribution to its mass from the vacuum expectation value of a scalar, under certain conditions, the ground state of particle number one contains a 'dimple' or shallow scalar field condensate around the particle. We argue that this is not the case. A careful analysis, taking into account quantum mechanics, shows that the semi-classical approximation is a poor one. We find that there are no energetically favored one-particle dimple solutions for perturbative couplings.

  2. Electroweak phase transitions

    SciTech Connect

    Anderson, G.W.

    1991-09-16

    An analytic treatment of the one Higgs doublet, electroweak phase transition is given. The phase transition is first order, occurs by the nucleation of thin walled bubbles and completes at a temperature where the order parameter, {l angle}{phi}{r angle}{sub T} is significantly smaller than it is when the origin becomes absolutely unstable. The rate of anomalous baryon number violation is an exponentially function of {l angle}{phi}{r angle}{sub T}. In very minimal extensions of the standard model it is quite easy to increase {l angle}{phi}{r angle}{sub T} so that anomalous baryon number violation is suppressed after completion of the phase transition. Hence baryogenesis at the electroweak phase transition is tenable in minimal of the standard model. In some cases additional phase transitions are possible. For a light Higgs boson, when the top quark mass is sufficiently large, the state where the Higgs field has a vacuum expectation value {l angle}{phi}{r angle} = 246 GeV is not the true minimum of the Higgs potential. When this is the case, and when the top quark mass exceeds some critical value, thermal fluctuations in the early universe would have rendered the state {l angle}{phi}{r angle} = 246 GeV unstable. The requirement that the state {l angle}{phi}{r angle} = 246 GeV is sufficiently long lived constrains the masses of the Higgs boson and the top quark. Finally, we consider whether local phase transitions can be induced by heavy particles which act as seeds for deformations in the scalar field.

  3. Electroweak phase transitions

    SciTech Connect

    Anderson, G.W.

    1991-09-16

    An analytic treatment of the one Higgs doublet, electroweak phase transition is given. The phase transition is first order, occurs by the nucleation of thin walled bubbles and completes at a temperature where the order parameter, {l_angle}{phi}{r_angle}{sub T} is significantly smaller than it is when the origin becomes absolutely unstable. The rate of anomalous baryon number violation is an exponentially function of {l_angle}{phi}{r_angle}{sub T}. In very minimal extensions of the standard model it is quite easy to increase {l_angle}{phi}{r_angle}{sub T} so that anomalous baryon number violation is suppressed after completion of the phase transition. Hence baryogenesis at the electroweak phase transition is tenable in minimal of the standard model. In some cases additional phase transitions are possible. For a light Higgs boson, when the top quark mass is sufficiently large, the state where the Higgs field has a vacuum expectation value {l_angle}{phi}{r_angle} = 246 GeV is not the true minimum of the Higgs potential. When this is the case, and when the top quark mass exceeds some critical value, thermal fluctuations in the early universe would have rendered the state {l_angle}{phi}{r_angle} = 246 GeV unstable. The requirement that the state {l_angle}{phi}{r_angle} = 246 GeV is sufficiently long lived constrains the masses of the Higgs boson and the top quark. Finally, we consider whether local phase transitions can be induced by heavy particles which act as seeds for deformations in the scalar field.

  4. Accurate measurement of heteronuclear dipolar couplings by phase-alternating R-symmetry (PARS) sequences in magic angle spinning NMR spectroscopy

    NASA Astrophysics Data System (ADS)

    Hou, Guangjin; Lu, Xingyu; Vega, Alexander J.; Polenova, Tatyana

    2014-09-01

    We report a Phase-Alternating R-Symmetry (PARS) dipolar recoupling scheme for accurate measurement of heteronuclear 1H-X (X = 13C, 15N, 31P, etc.) dipolar couplings in MAS NMR experiments. It is an improvement of conventional C- and R-symmetry type DIPSHIFT experiments where, in addition to the dipolar interaction, the 1H CSA interaction persists and thereby introduces considerable errors in the dipolar measurements. In PARS, phase-shifted RN symmetry pulse blocks applied on the 1H spins combined with π pulses applied on the X spins at the end of each RN block efficiently suppress the effect from 1H chemical shift anisotropy, while keeping the 1H-X dipolar couplings intact. Another advantage over conventional DIPSHIFT experiments, which require the signal to be detected in the form of a reduced-intensity Hahn echo, is that the series of π pulses refocuses the X chemical shift and avoids the necessity of echo formation. PARS permits determination of accurate dipolar couplings in a single experiment; it is suitable for a wide range of MAS conditions including both slow and fast MAS frequencies; and it assures dipolar truncation from the remote protons. The performance of PARS is tested on two model systems, [15N]-N-acetyl-valine and [U-13C,15N]-N-formyl-Met-Leu-Phe tripeptide. The application of PARS for site-resolved measurement of accurate 1H-15N dipolar couplings in the context of 3D experiments is presented on U-13C,15N-enriched dynein light chain protein LC8.

  5. Hydrogeologic investigation and establishment of a permanent multi-observational well network in Aiken, Allendale, and Barnwell Counties, South Carolina. Phase VIII

    SciTech Connect

    Gellici, J.A.; Gawne, C.E.

    1996-02-01

    The Lower Savannah River Project was established in 1986 to improve our understanding of the hydrogeologic conditions in west-central South Carolina. Six progress reports have been written since 1987. This report covers the period from July 1, 1994, to June 30, 1995. During the current phase, work focused on locating and procuring suitable sites for future well clusters; drafting well-construction specifications and bid packages; drilling monitoring wells at site C-7; and completing two comprehensive reports. Land was acquired for three future well-cluster sites: C-11, C-13, and C-15. Site C-11 will be located at the Oakwood Fire Tower in Aiken County. This land was made available through the South Carolina Forestry Commission. Land for site C-13 was donated by the Wildlife Division of the South Carolina Department of Natural Resources and will be located at Little Hell Landing on the Savannah River flood plain southwest of Millet in Allendale County. Site C-15 will be located at Gillisonville in northern Jasper County. A 0.9-acre parcel of land was purchased from Westvaco, Inc., for this site. Well specifications and bid packages were drawn up for the construction of seven monitoring wells at site C-10, three at C-13, and two at C-15. Specific-capacity values of nine wells at site C-7 range from 0.3 to 20.6 gpm/ft (gallons per minute per foot of drawdown). Two deep Cretaceous wells were drilled at site C-7, one each in the Midville and Dublin aquifer systems. An upward hydraulic gradient exists between the aquifers. Two comprehensive reports were completed during this phase of the project: (1) a compilation and interpretation of data collected from the project since its inception in 1986, and (2) a detailed description of the hydrogeologic framework of west-central South Carolina and the hydrologic characteristics of the aquifers and confining units.

  6. Compressive phase contrast tomography

    NASA Astrophysics Data System (ADS)

    Maia, F.; MacDowell, A.; Marchesini, S.; Padmore, H. A.; Parkinson, D. Y.; Pien, J.; Schirotzek, A.; Yang, C.

    2010-08-01

    When x-rays penetrate soft matter, their phase changes more rapidly than their amplitude. Interference effects visible with high brightness sources creates higher contrast, edge enhanced images. When the object is piecewise smooth (made of big blocks of a few components), such higher contrast datasets have a sparse solution. We apply basis pursuit solvers to improve SNR, remove ring artifacts, reduce the number of views and radiation dose from phase contrast datasets collected at the Hard X-Ray Micro Tomography Beamline at the Advanced Light Source. We report a GPU code for the most computationally intensive task, the gridding and inverse gridding algorithm (non uniform sampled Fourier transform).

  7. Linear phase compressive filter

    DOEpatents

    McEwan, T.E.

    1995-06-06

    A phase linear filter for soliton suppression is in the form of a laddered series of stages of non-commensurate low pass filters with each low pass filter having a series coupled inductance (L) and a reverse biased, voltage dependent varactor diode, to ground which acts as a variable capacitance (C). L and C values are set to levels which correspond to a linear or conventional phase linear filter. Inductance is mapped directly from that of an equivalent nonlinear transmission line and capacitance is mapped from the linear case using a large signal equivalent of a nonlinear transmission line. 2 figs.

  8. Linear phase compressive filter

    DOEpatents

    McEwan, Thomas E.

    1995-01-01

    A phase linear filter for soliton suppression is in the form of a laddered series of stages of non-commensurate low pass filters with each low pass filter having a series coupled inductance (L) and a reverse biased, voltage dependent varactor diode, to ground which acts as a variable capacitance (C). L and C values are set to levels which correspond to a linear or conventional phase linear filter. Inductance is mapped directly from that of an equivalent nonlinear transmission line and capacitance is mapped from the linear case using a large signal equivalent of a nonlinear transmission line.

  9. Quantum phase slip noise

    NASA Astrophysics Data System (ADS)

    Semenov, Andrew G.; Zaikin, Andrei D.

    2016-07-01

    Quantum phase slips (QPSs) generate voltage fluctuations in superconducting nanowires. Employing the Keldysh technique and making use of the phase-charge duality arguments, we develop a theory of QPS-induced voltage noise in such nanowires. We demonstrate that quantum tunneling of the magnetic flux quanta across the wire yields quantum shot noise which obeys Poisson statistics and is characterized by a power-law dependence of its spectrum SΩ on the external bias. In long wires, SΩ decreases with increasing frequency Ω and vanishes beyond a threshold value of Ω at T →0 . The quantum coherent nature of QPS noise yields nonmonotonous dependence of SΩ on T at small Ω .

  10. Compressive Phase Contrast Tomography

    SciTech Connect

    Maia, Filipe; MacDowell, Alastair; Marchesini, Stefano; Padmore, Howard A.; Parkinson, Dula Y.; Pien, Jack; Schirotzek, Andre; Yang, Chao

    2010-09-01

    When x-rays penetrate soft matter, their phase changes more rapidly than their amplitude. Interference effects visible with high brightness sources creates higher contrast, edge enhanced images. When the object is piecewise smooth (made of big blocks of a few components), such higher contrast datasets have a sparse solution. We apply basis pursuit solvers to improve SNR, remove ring artifacts, reduce the number of views and radiation dose from phase contrast datasets collected at the Hard X-Ray Micro Tomography Beamline at the Advanced Light Source. We report a GPU code for the most computationally intensive task, the gridding and inverse gridding algorithm (non uniform sampled Fourier transform).

  11. GAS PHASE EXPOSURE HISTORY DERIVED FROM MATERIAL PHASE CONCENTRATION PROFILES USING SOLID PHASE MICRO-EXTRACTION

    EPA Science Inventory

    EPA Identifier: F8P31059
    Title: Gas Phase Exposure History Derived from Material Phase Concentration Profiles Using Solid Phase Micro-Extraction
    Fellow (Principal Investigator): Jonathan Lewis McKinney
    Institution: University of Missouri - ...

  12. Phase interpolation circuits using frequency multiplication for phased arrays

    NASA Technical Reports Server (NTRS)

    Caron, P. R.; Mailloux, R. J.

    1970-01-01

    Antenna phasing circuit is described with the following advantages - 1/ increased number of phased elements, 2/ current repetition for each array element, 3/ circuit simplicity, and 4/ accurate phase interpolation. This circuit functions with Huggins Scan or with nearly any other phasing system.

  13. Suppressing phase errors from vibration in phase-shifting interferometry

    SciTech Connect

    Deck, Leslie L.

    2009-07-10

    A general method for reducing the influence of vibrations in phase-shifting interferometry corrects the surface phase map through a spectral analysis of a ''phase-error pattern,'' a plot of the interference intensity versus the measured phase, for each phase-shifted image. The method is computationally fast, applicable to any phase-shifting algorithm and interferometer geometry, has few restrictions on surface shape, and unlike spatial Fourier methods, high density spatial carrier fringes are not required, although at least a fringe of phase departure is recommended. Over a 100x reduction in vibrationally induced surface distortion is achieved for small amplitude vibrations on real data.

  14. Soviet phase conjugation research

    SciTech Connect

    Fisher, R.A.; Boyd, R.W.; Klein, M.B.; Kurnit, N.A.; Milonni, P.W.; Rockwell, D.A.; Yeh, P.

    1990-09-01

    Optical phase conjugation is a Soviet-discovered technique that applies nonlinear optical effects to automatically manipulate laser beams while automatically correcting for arbitrary distortions. Optical phase conjugation can aid in providing improved configurations for average-power and high-peak-power laser systems; it can provide nearly automatic pointing and tracking laser systems; and it can provide many other practical applications (both military and nonmilitary). Here it is important to note that 100- to 1000-watt systems are also of significant importance, not just ultra-high-energy or high-power lasers designed to do significant structural damage at significant distances. One class of phase conjugation techniques, namely, stimulated Brillouin scattering, along with its four-wave mixing counterpart, Brillioun-enhanced four-wave mixing, has been the hallmark of the Soviet effort -- with nearly all contributions (both theoretical and experimental) arising from the Soviet Union. Both stimulated Brillouin scattering and Brillouin-enhanced four-wave mixing arise from the same electrostrictive nonlinearity, where the presence of a gradient in the optical intensity produces a force on the fluid. Scientists in the United States started studying optical phase conjugation approximately five years after Soviet scientists, and initially concentrated on areas quite different from those of Soviet emphasis.

  15. Phase change compositions

    DOEpatents

    Salyer, Ival O.

    1989-01-01

    Compositions containing crystalline, straight chain, alkyl hydrocarbons as phase change materials including cementitious compositions containing the alkyl hydrocarbons neat or in pellets or granules formed by incorporating the alkyl hydrocarbons in polymers or rubbers; and polymeric or elastomeric compositions containing alkyl hydrocarbons.

  16. Phase change compositions

    DOEpatents

    Salyer, Ival O.; Griffen, Charles W.

    1986-01-01

    Compositions containing crystalline, long chain, alkyl hydrocarbons as phase change materials including cementitious compositions containing the alkyl hydrocarbons neat or in pellets or granules formed by incorporating the alkyl hydrocarbons in polymers or rubbers; and polymeric or elastomeric compositions containing alkyl hydrocarbons.

  17. Low gravity phase separator

    NASA Technical Reports Server (NTRS)

    Smoot, G. F.; Pope, W. L.; Smith, L. (Inventor)

    1977-01-01

    An apparatus is described for phase separating a gas-liquid mixture as might exist in a subcritical cryogenic helium vessel for cooling a superconducting magnet at low gravity such as in planetary orbit, permitting conservation of the liquid and extended service life of the superconducting magnet.

  18. Apodized Phase Mask Coronagraphs

    NASA Astrophysics Data System (ADS)

    Carlotti, Alexis

    2013-01-01

    Among the optical instruments proposed to detect and characterize exoplanets, phase masks coronagraphs offer very small inner working angles. Designed for off-axis telescopes, their performance is greatly reduced when used with centrally obstructed apertures such as those of the Palomar telescope, the very large telescope, or the James Webb space telescope. However, a clear circular aperture is not the only pupil shape for which a phase mask coronagraph can work properly. In fact, for a given centrally obstructed aperture, we show that it is possible to compute optimal apodizers that help achieve stellar extinction levels similar to those obtained in the ideal case of an off-axis telescope. Trade-offs exist between these levels, the transmission of the apodizer, and the area covered by the Lyot stop. We detail the Fourier optics formalism that makes these optimizations possible, as well as a few examples of shaped pupils. Some are designed for a four-quadrants phase mask, and some others for a vortex phase mask. We also offer a comparison with a coronagraph solely composed of a shaped pupil.

  19. SSIP Phase I Roadmap

    ERIC Educational Resources Information Center

    Vinh, Megan; Lucas, Anne; Taylor, Cornelia; Kelley, Grace; Kasprzak, Christina

    2014-01-01

    This roadmap provides a description of the activities involved in the development of the State Systemic Improvement Plan (SSIP) (SPP/APR Indicators C11 and B17) due to the Office of Special Education Programs (OSEP) on April 1, 2015. The roadmap is intended to support states with completing Phase I of the SSIP process. This document provides…

  20. Advanced Virgo phase cameras

    NASA Astrophysics Data System (ADS)

    van der Schaaf, L.; Agatsuma, K.; van Beuzekom, M.; Gebyehu, M.; van den Brand, J.

    2016-05-01

    A century after the prediction of gravitational waves, detectors have reached the sensitivity needed to proof their existence. One of them, the Virgo interferometer in Pisa, is presently being upgraded to Advanced Virgo (AdV) and will come into operation in 2016. The power stored in the interferometer arms raises from 20 to 700 kW. This increase is expected to introduce higher order modes in the beam, which could reduce the circulating power in the interferometer, limiting the sensitivity of the instrument. To suppress these higher-order modes, the core optics of Advanced Virgo is equipped with a thermal compensation system. Phase cameras, monitoring the real-time status of the beam constitute a critical component of this compensation system. These cameras measure the phases and amplitudes of the laser-light fields at the frequencies selected to control the interferometer. The measurement combines heterodyne detection with a scan of the wave front over a photodetector with pin-hole aperture. Three cameras observe the phase front of these laser sidebands. Two of them monitor the in-and output of the interferometer arms and the third one is used in the control of the aberrations introduced by the power recycling cavity. In this paper the working principle of the phase cameras is explained and some characteristic parameters are described.

  1. String mediated phase transitions

    NASA Technical Reports Server (NTRS)

    Copeland, ED; Haws, D.; Rivers, R.; Holbraad, S.

    1988-01-01

    It is demonstrated from first principles how the existence of string-like structures can cause a system to undergo a phase transition. In particular, the role of topologically stable cosmic string in the restoration of spontaneously broken symmetries is emphasized. How the thermodynamic properties of strings alter when stiffness and nearest neighbor string-string interactions are included is discussed.

  2. Adaptive MGS Phase Retrieval

    NASA Technical Reports Server (NTRS)

    Basinger, Scott A.; Bikkannavar, Siddarayappa; Cohen, David; Green, Joseph J.; Lou, John; Ohara, Catherine; Redding, David; Shi, Fang

    2008-01-01

    Adaptive MGS Phase Retrieval software uses the Modified Gerchberg-Saxton (MGS) algorithm, an image-based sensing method that can turn any focal plane science instrument into a wavefront sensor, avoiding the need to use external metrology equipment. Knowledge of the wavefront enables intelligent control of active optical systems.

  3. Fun with Phase Changes

    ERIC Educational Resources Information Center

    Purvis, David

    2006-01-01

    A lot of good elementary science involves studying solids, liquids, and gases, and some inquiry-based activities that are easy to set up and do. In this article, the author presents activities pertaining to simple phase change. Using water as the example, these activities introduce upper-grade students to the idea of the arrangement of molecules…

  4. Semiconductor Laser Phased Array

    NASA Technical Reports Server (NTRS)

    Katz, J.

    1985-01-01

    Oscillations synchronized and modulated individually for beam steering. Phased array of GaAs infrared lasers put out powerful electronically-steerable coherent beam. Fabricated as integrated circuit on GaAs chip, new device particularly suited to optical communications, optical data processing and optical detection and ranging systems.

  5. DELTA PHASE PLUTONIUM ALLOYS

    DOEpatents

    Cramer, E.M.; Ellinger, F.H.; Land. C.C.

    1960-03-22

    Delta-phase plutonium alloys were developed suitable for use as reactor fuels. The alloys consist of from 1 to 4 at.% zinc and the balance plutonium. The alloys have good neutronic, corrosion, and fabrication characteristics snd possess good dimensional characteristics throughout an operating temperature range from 300 to 490 deg C.

  6. Mentoring Phases and Outcomes.

    ERIC Educational Resources Information Center

    Chao, Georgia T.

    1997-01-01

    Data from 178 proteges supported Kram's model of mentoring phases: initiation, cultivation, separation, and redefinition. Data from 82 current and 69 former proteges were compared to those from 93 who were never mentored. Mentees had better career outcomes, organizational socialization, and job satisfaction; those not mentored had slightly higher…

  7. Introduction to phasing

    PubMed Central

    Taylor, Garry L.

    2010-01-01

    When collecting X-ray diffraction data from a crystal, we measure the intensities of the diffracted waves scattered from a series of planes that we can imagine slicing through the crystal in all directions. From these intensities we derive the amplitudes of the scattered waves, but in the experiment we lose the phase information; that is, how we offset these waves when we add them together to reconstruct an image of our molecule. This is generally known as the ‘phase problem’. We can only derive the phases from some knowledge of the molecular structure. In small-molecule crystallography, some basic assumptions about atomicity give rise to relationships between the amplitudes from which phase information can be extracted. In protein crystallography, these ab initio methods can only be used in the rare cases in which there are data to at least 1.2 Å resolution. For the majority of cases in protein crystallography phases are derived either by using the atomic coordinates of a structurally similar protein (molecular replacement) or by finding the positions of heavy atoms that are intrinsic to the protein or that have been added (methods such as MIR, MIRAS, SIR, SIRAS, MAD, SAD or com­binations of these). The pioneering work of Perutz, Kendrew, Blow, Crick and others developed the methods of isomorphous replacement: adding electron-dense atoms to the protein without disturbing the protein structure. Nowadays, methods from small-molecule crystallography can be used to find the heavy-atom substructure and the phases for the whole protein can be bootstrapped from this prior knowledge. More recently, improved X-ray sources, detectors and software have led to the routine use of anomalous scattering to obtain phase information from either incorporated selenium or intrinsic sulfurs. In the best cases, only a single set of X-ray data (SAD) is required to provide the positions of the anomalous scatters, which together with density-modification procedures can reveal

  8. Phase Operator and Phase State in Thermo Field Dynamics

    NASA Astrophysics Data System (ADS)

    Fan, Hong-Yi; Jiang, Nian-Quan

    We extend the Susskind-Glogower phase operator and phase state in quantum optics to thermo field dynamics (TFD). Based on the thermo entangled state representation, we introduce thermo excitation and de-excitation operators with which the phase operator and phase state in TFD can be constructed. The phase state treated as a limiting case of a new SU(1, 1) coherent states is also exhibited.

  9. Phase II Final Report

    SciTech Connect

    Schuknecht, Nate; White, David; Hoste, Graeme

    2014-09-11

    The SkyTrough DSP will advance the state-of-the-art in parabolic troughs for utility applications, with a larger aperture, higher operating temperature, and lower cost. The goal of this project was to develop a parabolic trough collector that enables solar electricity generation in the 2020 marketplace for a 216MWe nameplate baseload power plant. This plant requires an LCOE of 9¢/kWhe, given a capacity factor of 75%, a fossil fuel limit of 15%, a fossil fuel cost of $6.75/MMBtu, $25.00/kWht thermal storage cost, and a domestic installation corresponding to Daggett, CA. The result of our optimization was a trough design of larger aperture and operating temperature than has been fielded in large, utility scale parabolic trough applications: 7.6m width x 150m SCA length (1,118m2 aperture), with four 90mm diameter × 4.7m receivers per mirror module and an operating temperature of 500°C. The results from physical modeling in the System Advisory Model indicate that, for a capacity factor of 75%: The LCOE will be 8.87¢/kWhe. SkyFuel examined the design of almost every parabolic trough component from a perspective of load and performance at aperture areas from 500 to 2,900m2. Aperture-dependent design was combined with fixed quotations for similar parts from the commercialized SkyTrough product, and established an installed cost of $130/m2 in 2020. This project was conducted in two phases. Phase I was a preliminary design, culminating in an optimum trough size and further improvement of an advanced polymeric reflective material. This phase was completed in October of 2011. Phase II has been the detailed engineering design and component testing, which culminated in the fabrication and testing of a single mirror module. Phase II is complete, and this document presents a summary of the comprehensive work.

  10. Multicomponent three-phase equilibria

    SciTech Connect

    Ho, C.K.

    1995-06-01

    This paper presents the relations that describe thermodynamic equilibrium in a three-phase system. Multiple components, including air, water, and oil components, are considered in three phases: (1) aqueous, (2) oil, and (3) gas. Primary variables are specified for each of seven possible phase combinations. These primary variables are then used to determine the necessary secondary variables to completely describe the system. Criteria are also developed to check the stability of each phase configuration and determine possible transitions from one phase configuration to another phase configuration via phase appearances and disappearances.

  11. Noisy quantum phase communication channels

    NASA Astrophysics Data System (ADS)

    Teklu, Berihu; Trapani, Jacopo; Olivares, Stefano; Paris, Matteo G. A.

    2015-06-01

    We address quantum phase channels, i.e communication schemes where information is encoded in the phase-shift imposed to a given signal, and analyze their performances in the presence of phase diffusion. We evaluate mutual information for coherent and phase-coherent signals, and for both ideal and realistic phase receivers. We show that coherent signals offer better performances than phase-coherent ones, and that realistic phase channels are effective ones in the relevant regime of low energy and large alphabets.

  12. Phase-field modeling of multi-phase solidification

    NASA Astrophysics Data System (ADS)

    Nestler, Britta; Wheeler, Adam A.

    2002-08-01

    A phase-field model for a general class of multi-phase metallic alloys is now proposed which describes both multi-phase solidification phenomena as well as polycrystalline grain structures. The model serves as a computational method to simulate the motion and kinetics of multiple phase boundaries and enables the visualization of the diffusion processes and of the phase transitions in multi-phase systems. Numerical simulations are presented which illustrate the capability of the phase-field model to recover a variety of complex experimental growth structures. In particular, the phase-field model can be used to simulate microstructure evolutions in eutectic, peritectic and monotectic alloys. In addition, polycrystalline grain structures with effects such as wetting, grain growth, symmetry properties of adjacent triple junctions in thin film samples and stability criteria at multiple junctions are described by phase-field simulations.

  13. Gas-phase and X-ray studies of branched ligands: Cu(II) coordination polymer formed by Nα, Nɛ, Nɛ-tris(cyanoethyl)- L-lysine

    NASA Astrophysics Data System (ADS)

    Janiszewska, Jolanta; Urbańczyk-Lipkowska, Zofia

    2006-05-01

    A small dendrimeric compound, Nα, Nɛ, Nɛ-tris(dicyanoethyl)- L-lysine—C 15H 23N 5O 2 ( 1) was synthesized and used for the construction of Cu(II) complex—[Cu(C 15H 23N 5O 2) 2(ClO 4) 2·H 2O] ( 3). In the gas-phase, the dimeric and trimeric clusters of 1, surrounding Na + core were observed. The aggregates with a complex structure were found for the mixtures of 1 and Cu(ClO 4) 2 at various ratios in ESI-MS experiments. The X-ray studies showed that a new 1D coordination polymer ( 3), connected by the Cu…N tbnd6 C coordination with the α- N-cyanoethyl group of ligand is formed in a solid-state. The structure contains penta-coordinated Cu(II) with the Cu-Cu separation 7.820(1)-7.927(1) Å. The Cu(II)-coordinated branched ligands form cavities where three perchlorate anions are encapsulated into the void space by the electrostatic and van der Waals interactions. The remaining three perchlorate anions are hydrogen-bonded to the ɛ-NH + groups. Thus, the polymeric structure shows properties postulated for dendrimers, where charged groups can be isolated by the non-polar branches from the outside environment. Both gas-phase and X-ray studies show predominance of the 2:1 aggregation pattern between ligand 1 and Cu 2+ atoms.

  14. Advanced phase change materials and systems for solar passive heating and cooling of residential buildings

    SciTech Connect

    Salyer, I.O.; Sircar, A.K.; Dantiki, S.

    1988-01-01

    During the last three years under the sponsorship of the DOE Solar Passive Division, the University of Dayton Research Institute (UDRI) has investigated four phase change material (PCM) systems for utility in thermal energy storage for solar passive heating and cooling applications. From this research on the basis of cost, performance, containment, and environmental acceptability, we have selected as our current and most promising series of candidate phase change materials, C-15 to C-24 linear crystalline alkyl hydrocarbons. The major part of the research during this contract period was directed toward the following three objectives. Find, test, and develop low-cost effective phase change materials (PCM) that melt and freeze sharply in the comfort temperature range of 73--77{degree}F for use in solar passive heating and cooling of buildings. Define practical materials and processes for fire retarding plasterboard/PCM building products. Develop cost-effective methods for incorporating PCM into building construction materials (concrete, plasterboard, etc.) which will lead to the commercial manufacture and sale of PCM-containing products resulting in significant energy conservation.

  15. Phase calibration generator

    NASA Technical Reports Server (NTRS)

    Sigman, E. H.

    1988-01-01

    A phase calibration system was developed for the Deep Space Stations to generate reference microwave comb tones which are mixed in with signals received by the antenna. These reference tones are used to remove drifts of the station's receiving system from the detected data. This phase calibration system includes a cable stabilizer which transfers a 20 MHz reference signal from the control room to the antenna cone. The cable stabilizer compensates for delay changes in the long cable which connects its control room subassembly to its antenna cone subassembly in such a way that the 20 MHz is transferred to the cone with no significant degradation of the hydrogen maser atomic clock stability. The 20 MHz reference is used by the comb generator and is also available for use as a reference for receiver LO's in the cone.

  16. Phase-Measuring System

    NASA Technical Reports Server (NTRS)

    Davis, W. T.

    1986-01-01

    System developed and used at Langley Research Center measures phase between two signals of same frequency or between two signals, one of which is harmonic multiple of other. Simple and inexpensive device combines digital and analog components to give accurate phase measurements. One signal at frequency f fed to pulse shaper, produces negative pulse at time t4. Pulse applied to control input of sample-and-hold module 1. Second signal, at frequency nf, fed to zero-crossover amplifier, producing square wave at time t. Signal drives first one-shot producing narrow negative pulse at t1. Signal then drives second one-shot producing narrow positive pulse at time t2. This pulse used to turn on solid-state switch and reset integrator circuit to zero.

  17. High power phase shifter

    SciTech Connect

    Foster, B.; Gonin, I.; Khabiboulline, T.; Makarov, A.; Solyak, N.; Terechkine, I.; Wildman, D.; /Fermilab

    2005-05-01

    One of the approaches to power distribution system of a superconducting proton linac under discussion at FNAL requires development of a fast-action, megawatt-range phase shifter. Using a couple of this kind of devices with a waveguide hybrid junction can allow independent control of phase and amplitude of RF power at the input of each superconducting cavity, which will result in significant saving in number of klystrons and modulators required for the accelerator. A prototype of a waveguide version of the shifter that uses Yttrium-Iron Garnet (YIG) blocks was developed and tested. This report presents design concept of the device, and main results of simulation and proof-of-principle tests.

  18. Phase shifting diffraction interferometer

    DOEpatents

    Sommargren, Gary E.

    1996-01-01

    An interferometer which has the capability of measuring optical elements and systems with an accuracy of .lambda./1000 where .lambda. is the wavelength of visible light. Whereas current interferometers employ a reference surface, which inherently limits the accuracy of the measurement to about .lambda./50, this interferometer uses an essentially perfect spherical reference wavefront generated by the fundamental process of diffraction. This interferometer is adjustable to give unity fringe visibility, which maximizes the signal-to-noise, and has the means to introduce a controlled prescribed relative phase shift between the reference wavefront and the wavefront from the optics under test, which permits analysis of the interference fringe pattern using standard phase extraction algorithms.

  19. Phase shifting interferometer

    DOEpatents

    Sommargren, G.E.

    1999-08-03

    An interferometer is disclosed which has the capability of measuring optical elements and systems with an accuracy of {lambda}/1000 where {lambda} is the wavelength of visible light. Whereas current interferometers employ a reference surface, which inherently limits the accuracy of the measurement to about {lambda}/50, this interferometer uses an essentially perfect spherical reference wavefront generated by the fundamental process of diffraction. Whereas current interferometers illuminate the optic to be tested with an aberrated wavefront which also limits the accuracy of the measurement, this interferometer uses an essentially perfect spherical measurement wavefront generated by the fundamental process of diffraction. This interferometer is adjustable to give unity fringe visibility, which maximizes the signal-to-noise, and has the means to introduce a controlled prescribed relative phase shift between the reference wavefront and the wavefront from the optics under test, which permits analysis of the interference fringe pattern using standard phase extraction algorithms. 11 figs.

  20. Phase shifting interferometer

    DOEpatents

    Sommargren, Gary E.

    1999-01-01

    An interferometer which has the capability of measuring optical elements and systems with an accuracy of .lambda./1000 where .lambda. is the wavelength of visible light. Whereas current interferometers employ a reference surface, which inherently limits the accuracy of the measurement to about .lambda./50, this interferometer uses an essentially perfect spherical reference wavefront generated by the fundamental process of diffraction. Whereas current interferometers illuminate the optic to be tested with an aberrated wavefront which also limits the accuracy of the measurement, this interferometer uses an essentially perfect spherical measurement wavefront generated by the fundamental process of diffraction. This interferometer is adjustable to give unity fringe visibility, which maximizes the signal-to-noise, and has the means to introduce a controlled prescribed relative phase shift between the reference wavefront and the wavefront from the optics under test, which permits analysis of the interference fringe pattern using standard phase extraction algorithms.

  1. Phase shifting diffraction interferometer

    DOEpatents

    Sommargren, G.E.

    1996-08-29

    An interferometer which has the capability of measuring optical elements and systems with an accuracy of {lambda}/1000 where {lambda} is the wavelength of visible light. Whereas current interferometers employ a reference surface, which inherently limits the accuracy of the measurement to about {lambda}/50, this interferometer uses an essentially perfect spherical reference wavefront generated by the fundamental process of diffraction. This interferometer is adjustable to give unity fringe visibility, which maximizes the signal-to-noise, and has the means to introduce a controlled prescribed relative phase shift between the reference wavefront and the wavefront from the optics under test, which permits analysis of the interference fringe pattern using standard phase extraction algorithms. 8 figs.

  2. Spatial Phase Imaging

    NASA Technical Reports Server (NTRS)

    2006-01-01

    Frequently, scientists grow crystals by dissolving a protein in a specific liquid solution, and then allowing that solution to evaporate. The methods used next have been, variously, invasive (adding a dye that is absorbed by the protein), destructive (crushing protein/salt-crystal mixtures and observing differences between the crushing of salt and protein), or costly and time-consuming (X-ray crystallography). In contrast to these methods, a new technology for monitoring protein growth, developed in part through NASA Small Business Innovation Research (SBIR) funding from Marshall Space Flight Center, is noninvasive, nondestructive, rapid, and more cost effective than X-ray analysis. The partner for this SBIR, Photon-X, Inc., of Huntsville, Alabama, developed spatial phase imaging technology that can monitor crystal growth in real time and in an automated mode. Spatial phase imaging scans for flaws quickly and produces a 3-D structured image of a crystal, showing volumetric growth analysis for future automated growth.

  3. Optically interconnected phased arrays

    NASA Technical Reports Server (NTRS)

    Bhasin, Kul B.; Kunath, Richard R.

    1988-01-01

    Phased-array antennas are required for many future NASA missions. They will provide agile electronic beam forming for communications and tracking in the range of 1 to 100 GHz. Such phased arrays are expected to use several hundred GaAs monolithic integrated circuits (MMICs) as transmitting and receiving elements. However, the interconnections of these elements by conventional coaxial cables and waveguides add weight, reduce flexibility, and increase electrical interference. Alternative interconnections based on optical fibers, optical processing, and holography are under evaluation as possible solutions. In this paper, the current status of these techniques is described. Since high-frequency optical components such as photodetectors, lasers, and modulators are key elements in these interconnections, their performance and limitations are discussed.

  4. Measurement by phase severance

    SciTech Connect

    Noyes, H.P.

    1987-03-01

    It is claimed that the measurement process is more accurately described by ''quasi-local phase severance'' than by ''wave function collapse''. The approach starts from the observation that the usual route to quantum mechanics starting from the Hamilton-Jacobi equations throws away half the degrees of freedom, namely, the classical initial state parameters. To overcome this difficulty, the full set of Hamilton-Jacobi equations is interpreted as operator equations acting on a state vector. The measurement theory presented is based on the conventional S-matrix boundary condition of N/sub A/ free particles in the distant past and N/sub B/ free particles in the distant future and taking the usual free particle wave functions, multiplied by phase factors.

  5. Emergence and Phase Transitions

    NASA Astrophysics Data System (ADS)

    Sikkema, Arnold

    2006-05-01

    Phase transitions are well defined in physics through concepts such as spontaneous symmetry breaking, order parameter, entropy, and critical exponents. But emergence --- also exhibiting whole-part relations (such as top-down influence), unpredictability, and insensitivity to microscopic detail --- is a loosely-defined concept being used in many disciplines, particularly in psychology, biology, philosophy, as well as in physics[1,2]. I will review the concepts of emergence as used in the various fields and consider the extent to which the methods of phase transitions can clarify the usefulness of the concept of emergence both within the discipline of physics and beyond.1. Robert B. Laughlin, A Different Universe: Reinventing Physics from the Bottom Down (New York: Basic Books, 2005). 2. George F.R. Ellis, ``Physics and the Real World'', Physics Today, vol. 58, no. 7 (July 2005) pp. 49-54.

  6. Phase space quantum mechanics

    NASA Astrophysics Data System (ADS)

    Błaszak, Maciej; Domański, Ziemowit

    2012-02-01

    This paper develops an alternative formulation of quantum mechanics known as the phase space quantum mechanics or deformation quantization. It is shown that the quantization naturally arises as an appropriate deformation of the classical Hamiltonian mechanics. More precisely, the deformation of the point-wise product of observables to an appropriate noncommutative ⋆-product and the deformation of the Poisson bracket to an appropriate Lie bracket are the key elements in introducing the quantization of classical Hamiltonian systems. The formalism of the phase space quantum mechanics is presented in a very systematic way for the case of any smooth Hamiltonian function and for a very wide class of deformations. The considered class of deformations and the corresponding ⋆-products contains as a special case all deformations which can be found in the literature devoted to the subject of the phase space quantum mechanics. Fundamental properties of ⋆-products of observables, associated with the considered deformations are presented as well. Moreover, a space of states containing all admissible states is introduced, where the admissible states are appropriate pseudo-probability distributions defined on the phase space. It is proved that the space of states is endowed with a structure of a Hilbert algebra with respect to the ⋆-multiplication. The most important result of the paper shows that developed formalism is more fundamental than the axiomatic ordinary quantum mechanics which appears in the presented approach as the intrinsic element of the general formalism. The equivalence of two formulations of quantum mechanics is proved by observing that the Wigner-Moyal transform has all properties of the tensor product. This observation allows writing many previous results found in the literature in a transparent way, from which the equivalence of the two formulations of quantum mechanics follows naturally. In addition, examples of a free particle and a simple harmonic

  7. Phase Field Fracture Mechanics.

    SciTech Connect

    Robertson, Brett Anthony

    2015-11-01

    For this assignment, a newer technique of fracture mechanics using a phase field approach, will be examined and compared with experimental data for a bend test and a tension test. The software being used is Sierra Solid Mechanics, an implicit/explicit finite element code developed at Sandia National Labs in Albuquerque, New Mexico. The bend test experimental data was also obtained at Sandia Labs while the tension test data was found in a report online from Purdue University.

  8. Solid phase extraction membrane

    SciTech Connect

    Carlson, Kurt C; Langer, Roger L

    2002-11-05

    A wet-laid, porous solid phase extraction sheet material that contains both active particles and binder and that possesses excellent wet strength is described. The binder is present in a relatively small amount while the particles are present in a relatively large amount. The sheet material is sufficiently strong and flexible so as to be pleatable so that, for example, it can be used in a cartridge device.

  9. Compactification on phase space

    NASA Astrophysics Data System (ADS)

    Lovelady, Benjamin; Wheeler, James

    2016-03-01

    A major challenge for string theory is to understand the dimensional reduction required for comparison with the standard model. We propose reducing the dimension of the compactification by interpreting some of the extra dimensions as the energy-momentum portion of a phase-space. Such models naturally arise as generalized quotients of the conformal group called biconformal spaces. By combining the standard Kaluza-Klein approach with such a conformal gauge theory, we may start from the conformal group of an n-dimensional Euclidean space to form a 2n-dimensional quotient manifold with symplectic structure. A pair of involutions leads naturally to two n-dimensional Lorentzian manifolds. For n = 5, this leaves only two extra dimensions, with a countable family of possible compactifications and an SO(5) Yang-Mills field on the fibers. Starting with n=6 leads to 4-dimensional compactification of the phase space. In the latter case, if the two dimensions each from spacetime and momentum space are compactified onto spheres, then there is an SU(2)xSU(2) (left-right symmetric electroweak) field between phase and configuration space and an SO(6) field on the fibers. Such a theory, with minor additional symmetry breaking, could contain all parts of the standard model.

  10. Photoinduced phase transitions.

    PubMed

    Bennemann, K H

    2011-02-23

    Optically induced ultrafast electronic excitations with sufficiently long lifetimes may cause strong effects on phase transitions like structural and nonmetal→metal ones and on supercooling, supersaturation, etc. Examples are the transitions diamond→graphite, graphite→graphene, non-metal→metal, solid→liquid and vapor→liquid, solid. Photoinduced formation of graphene and water condensation of saturated or supersaturated vapor due to increased bonding amongst water molecules are of particular interest. These nonequilibrium transitions are an ultrafast response, on a few hundred fs time scale, to the fast low to large energy electronic excitations. The energy of the photons is converted into electronic energy via electronic excitations changing the cohesive energy. This changes the chemical potential controlling the phase transition. In view of the advances in laser optics photon induced transitions are expected to become an active area in nonequilibrium physics and phase transition dynamics. Conservation laws like energy or angular momentum conservation control the time during which the transitions occur. Since the photon induced effects result from weakening or strengthening of the bonding between the atoms or molecules transitions like solid/liquid, etc can be shifted in both directions. Photoinduced transitions will be discussed from a unified point of view. PMID:21411879

  11. Phases, phase equilibria, and phase rules in low-dimensional systems

    SciTech Connect

    Frolov, T.; Mishin, Y.

    2015-07-28

    We present a unified approach to thermodynamic description of one, two, and three dimensional phases and phase transformations among them. The approach is based on a rigorous definition of a phase applicable to thermodynamic systems of any dimensionality. Within this approach, the same thermodynamic formalism can be applied for the description of phase transformations in bulk systems, interfaces, and line defects separating interface phases. For both lines and interfaces, we rigorously derive an adsorption equation, the phase coexistence equations, and other thermodynamic relations expressed in terms of generalized line and interface excess quantities. As a generalization of the Gibbs phase rule for bulk phases, we derive phase rules for lines and interfaces and predict the maximum number of phases than may coexist in systems of the respective dimensionality.

  12. Phases, phase equilibria, and phase rules in low-dimensional systems.

    PubMed

    Frolov, T; Mishin, Y

    2015-07-28

    We present a unified approach to thermodynamic description of one, two, and three dimensional phases and phase transformations among them. The approach is based on a rigorous definition of a phase applicable to thermodynamic systems of any dimensionality. Within this approach, the same thermodynamic formalism can be applied for the description of phase transformations in bulk systems, interfaces, and line defects separating interface phases. For both lines and interfaces, we rigorously derive an adsorption equation, the phase coexistence equations, and other thermodynamic relations expressed in terms of generalized line and interface excess quantities. As a generalization of the Gibbs phase rule for bulk phases, we derive phase rules for lines and interfaces and predict the maximum number of phases than may coexist in systems of the respective dimensionality. PMID:26233156

  13. Digital phase-locked loop

    NASA Technical Reports Server (NTRS)

    Cliff, R. A. (Inventor)

    1975-01-01

    An digital phase-locked loop is provided for deriving a loop output signal from an accumulator output terminal. A phase detecting exclusive OR gate is fed by the loop digital input and output signals. The output of the phase detector is a bi-level digital signal having a duty cycle indicative of the relative phase of the input and output signals. The accumulator is incremented at a first rate in response to a first output level of the phase detector and at a second rate in response to a second output level of the phase detector.

  14. Monoclinic phases arising across thermal inter-ferroelectric phase transitions

    NASA Astrophysics Data System (ADS)

    Gu, Yijia; Xue, Fei; Lei, Shiming; Lummen, Tom T. A.; Wang, Jianjun; Gopalan, Venkatraman; Chen, Long-Qing

    2014-07-01

    Thermotropic phase boundaries (TPBs), as thermal analogs of morphotropic phase boundaries (MPBs), are associated with the thermal inter-ferroelectric phase transitions. Similar to an MPB, a TPB exhibits a characteristically flattened energy profile which favors polarization rotation, thus giving rise to a structurally bridging low-symmetry phase. We report on the kinetic process of thermal inter-ferroelectric phase transitions in BaTiO3 and KNbO3 using the phase-field method. The domain structures are found to play key roles in stabilizing the monoclinic phase. In simple domain structures, the monoclinic phase is a transient phase and cannot be stabilized into its neighboring phase regimes. However, by introducing structural inhomogeneity (orthogonal in-plane domain twins), we found that the monoclinic phase can be stabilized over a range of over 100 K across the transition. As a result, the piezoelectric properties are enhanced due to the stabilized monoclinic phase. In addition to the emergence of new piezoelectric components with monoclinic symmetry, most of the original components present in the tetragonal symmetry also show substantial enhancement with the rotation of polarization.

  15. VRA Modeling, phase 1

    NASA Technical Reports Server (NTRS)

    Kindt, Louis M.; Mullins, Michael E.; Hand, David W.; Kline, Andrew A.

    1995-01-01

    The destruction of organic contaminants in waste water for closed systems, such as that of Space Station, is crucial due to the need for recycling the waste water. A co-current upflow bubble column using oxygen as the gas phase oxidant and packed with catalyst particles consisting of a noble metal on an alumina substrate is being developed for this process. The objective of this study is to develop a plug-flow model that will predict the performance of this three phase reactor system in destroying a multicomponent mixture of organic contaminants in water. Mass balances on a series of contaminants and oxygen in both the liquid and gas phases are used to develop this model. These mass balances incorporate the gas-to-liquid and liquid-to-particle mass transfer coefficients, the catalyst effectiveness factor, and intrinsic reaction rate. To validate this model, a bench scale reactor has been tested at Michigan Technological University at elevated pressures (50-83 psig,) and a temperature range of 200 to 290 F. Feeds consisting of five dilute solutions of ethanol (approx. 10 ppm), chlorobenzene (approx. 20 ppb), formaldehyde (approx. 100 ppb), dimethyl sulfoxide (DMSO approx. 300 ppb), and urea (approx. 20 ppm) in water were tested individually with an oxygen mass flow rate of 0.009 lb/h. The results from these individual tests were used to develop the kinetic parameter inputs necessary for the computer model. The computer simulated results are compared to the experimental data obtained for all 5 components run in a mixture on the differential test column for a range of reactor contact times.

  16. Quantum phase magnification

    NASA Astrophysics Data System (ADS)

    Hosten, O.; Krishnakumar, R.; Engelsen, N. J.; Kasevich, M. A.

    2016-06-01

    Quantum metrology exploits entangled states of particles to improve sensing precision beyond the limit achievable with uncorrelated particles. All previous methods required detection noise levels below this standard quantum limit to realize the benefits of the intrinsic sensitivity provided by these states. We experimentally demonstrate a widely applicable method for entanglement-enhanced measurements without low-noise detection. The method involves an intermediate quantum phase magnification step that eases implementation complexity. We used it to perform squeezed-state metrology 8 decibels below the standard quantum limit with a detection system that has a noise floor 10 decibels above the standard quantum limit.

  17. FNAS phase partitions

    NASA Technical Reports Server (NTRS)

    Vanalstine, James M.

    1993-01-01

    Project NAS8-36955 D.O. #100 initially involved the following tasks: (1) evaluation of various coatings' ability to control wall wetting and surface zeta potential expression; (2) testing various methods to mix and control the demixing of phase systems; and (3) videomicroscopic investigation of cell partition. Three complementary areas were identified for modification and extension of the original contract. They were: (1) identification of new supports for column cell partition; (2) electrokinetic detection of protein adsorption; and (3) emulsion studies related to bioseparations.

  18. Athena: Assessment Phase Activities

    NASA Astrophysics Data System (ADS)

    Lumb, David; Ayre, Mark

    2015-09-01

    The Athena mission concept has been proposed by the community in response to science themes of the Hot and Energetic Universe. Unlike other, competitive, mission selection exercises this "Large" class observatory mission has essentially been pre-selected. Nevertheless it has to be demonstrated that Athena meets the programmatic constraints of 1Bn euro cost cap, and a readiness level appropriate for formal mission adoption by the end 2019. This should be confirmed through a Phase A study conducted with two parallel industry activities. We describe the technical and programmatic content of these and latest progress in space and ground segment definition.

  19. Autonomous Phase Retrieval Calibration

    NASA Technical Reports Server (NTRS)

    Estlin, Tara A.; Chien, Steve A.; Castano, Rebecca; Gaines, Daniel M.; Doubleday, Joshua R.; Schoolcraft, Josua B.; Oyake, Amalaye; Vaughs, Ashton G.; Torgerson, Jordan L.

    2011-01-01

    The Palomar Adaptive Optics System actively corrects for changing aberrations in light due to atmospheric turbulence. However, the underlying internal static error is unknown and uncorrected by this process. The dedicated wavefront sensor device necessarily lies along a different path than the science camera, and, therefore, doesn't measure the true errors along the path leading to the final detected imagery. This is a standard problem in adaptive optics (AO) called "non-common path error." The Autonomous Phase Retrieval Calibration (APRC) software suite performs automated sensing and correction iterations to calibrate the Palomar AO system to levels that were previously unreachable.

  20. Quantum phase magnification.

    PubMed

    Hosten, O; Krishnakumar, R; Engelsen, N J; Kasevich, M A

    2016-06-24

    Quantum metrology exploits entangled states of particles to improve sensing precision beyond the limit achievable with uncorrelated particles. All previous methods required detection noise levels below this standard quantum limit to realize the benefits of the intrinsic sensitivity provided by these states. We experimentally demonstrate a widely applicable method for entanglement-enhanced measurements without low-noise detection. The method involves an intermediate quantum phase magnification step that eases implementation complexity. We used it to perform squeezed-state metrology 8 decibels below the standard quantum limit with a detection system that has a noise floor 10 decibels above the standard quantum limit. PMID:27339982

  1. Vapor phase pyrolysis

    NASA Technical Reports Server (NTRS)

    Steurer, Wolfgang

    1992-01-01

    The vapor phase pyrolysis process is designed exclusively for the lunar production of oxygen. In this concept, granulated raw material (soil) that consists almost entirely of metal oxides is vaporized and the vapor is raised to a temperature where it dissociates into suboxides and free oxygen. Rapid cooling of the dissociated vapor to a discrete temperature causes condensation of the suboxides, while the oxygen remains essentially intact and can be collected downstream. The gas flow path and flow rate are maintained at an optimum level by control of the pressure differential between the vaporization region and the oxygen collection system with the aid of the environmental vacuum.

  2. Ion Phase Space Transport

    NASA Astrophysics Data System (ADS)

    Sheehan, Daniel Peter

    1987-09-01

    Experimental measurements are presented of ion phase space evolution in a collisionless magnetoplasma utilizing nonperturbing laser induced fluorescence (LIF) diagnostics. Ion configuration space and velocity space transport, and ion thermodynamic information were derived from the phase space diagrams for the following beam-plasma and obstacle-plasma systems:(UNFORMATTED TABLE OR EQUATION FOLLOWS) OBSTACLE & PLASMA SPECIES qquad disc & quad Ba ^+/e^ qquad disc & quad Ba^+/SF _6^-/e^ BEAM SPECIES & PLASMA SPECIES} qquad Ba^+ & quad Cs^+/e^ qquad Cs^+ & quad Ba^+/e^ qquad Ba^+ & quad Cs^+/SF_6 ^-/e^ qquad e^- & quad Ba^+ /e^ TABLE/EQUATION ENDS The ions were roughly mass symmetric. Plasma systems were reconstructed from multiple discrete Ba(II) ion velocity distributions with spatial, temporal, and velocity resolution of 1 mm^3, 2 musec, and 3 times 1010 cm ^3/sec^3 respectively. Phase space reconstructions indicated resonant ion response to the current-driven electrostatic ion cyclotron wave (EICW) in the case of an electron beam and to the ion cyclotron-cyclotron wave in the case of ion beams. Ion energization was observed in both systems. Local particle kinetic energy densities increase far above thermal levels in the presence of the EICW and ICCW. Time-resolved measurements of the EICW identified phase space particle bunching. The nonlinear evolution of f_{rm i}(x,v,t) was investigated for both beam systems. The near wake of conducting electrically floating disc obstacle was studied. Anomalous cross field diffusion (D_bot > 10 ^4 cm^2/sec) and ion energization were correlated with strong, low-frequency turbulence generated by the obstacle. Ion perpendicular kinetic energy densities doubled over thermal levels in the near wake. Upstream of the obstacle, l ~ 50 lambda_ {rm D}, a collisionless shock was indicated; far downstream, an ion flux peak was observed. Three negative ion plasma (NIP) sources were developed and characterized in the course of research: two

  3. Frequency discriminator/phase detector

    NASA Technical Reports Server (NTRS)

    Crow, R. B.

    1974-01-01

    Circuit provides dual function of frequency discriminator/phase detector which reduces frequency acquisition time without adding to circuit complexity. Both frequency discriminators, in evaluated frequency discriminator/phase detector circuits, are effective two decades above and below center frequency.

  4. Microcellular foams via phase separation

    SciTech Connect

    Young, A.T.

    1985-01-01

    A study of wide variety of processes for making plastic foams shows that phase separation processes for polymers from solutions offers the most viable methods for obtaining rigid plastic foams which met the physical requirements for fusion target designs. Four general phase separation methods have been shown to give polymer foams with densities less than 0.1 g/cm/sup 3/ and cell sizes of 30..mu..m or less. These methods involve the utilization of non-solvent, chemical or thermal cooling processes to achieve a controlled phase separation wherein either two distinct phases are obtained where the polymer phase is a continuous phase or two bicontinuous phases are obtained where both the polymer and solvent are interpenetrating, continuous, labyrinthine phases. Subsequent removal of the solvent gives the final foam structure.

  5. Structural, electronic and elastic properties of RERu2 (RE=Pr and Nd) Laves phase intermetallic compounds

    NASA Astrophysics Data System (ADS)

    Shrivastava, Deepika; Sanyal, Sankar P.

    2016-05-01

    We have performed the first-principles calculations to study the structural, electronic and elastic properties of RERu2 (RE = Pr and Nd) Laves phase intermetallic compounds using full-potential linearized augmented plane wave (FP-LAPW) method based on density functional theory (DFT) within the generalized gradient approximation (GGA) for exchange and correlation potential. The optimized lattices constant are in reasonable agreement with available experimental data. The electronic properties are analyzed in terms of band structures, total and partial density of states, which confirm their metallic character. The calculated elastic constants infer that these compounds are mechanically stable in C15 (MgCu2 type) structure and found to be ductile in nature.

  6. Stationary phase analysis of generalized cubic phase mask wavefront coding

    NASA Astrophysics Data System (ADS)

    Liu, Ming; Dong, Liquan; Zhao, Yuejin; Hui, Mei; Jia, Wei

    2013-07-01

    The modified generalized cubic phase mask (GCPM) has recently been applied in wavefront coding systems including infrared imaging and microscopy. In this paper, the stationary phase method is employed to analyze the GCPM characteristics. The SPA of the modulation transfer function (MTF) under misfocus aberration is derived for a wavefront coding system with a GCPM. The approximation corresponds with the Fast Fourier Transform (FFT) approach. On the basis of this approximation, we compare the characteristics of GCPM and cubic phase masks (CPM). A GCPM design approach based on stationary phase approximation is presented which helps to determine the initial parameter of phase mask, significantly decreasing the computational time required for numerical simulation.

  7. N-Consecutive-Phase Encoder

    NASA Technical Reports Server (NTRS)

    Divsalar, Dariush; Lee, Ho-Kyoung; Weber, Charles

    1995-01-01

    N-consecutive-phase encoder (NCPE) is conceptual encoder for generating alphabet of N consecutive full-response continuous-phase-modulation (CPM) signals. Enables use of binary preencoder of higher rate than used with simple continuous-phase encoder (CPE). NCPE makes possible to achieve power efficiencies and bandwidth efficiencies greater than conventional trellis coders with continuous-phase frequency-shift keying (CPFSK).

  8. Process for phase separation

    DOEpatents

    Comolli, Alfred G.

    1979-01-01

    This invention provides a continuous process for separating a gaseous phase from a hydrocarbon liquid containing carbonaceous particulates and gases. The liquid is fed to a cylindrical separator, with the gaseous phase being removed therefrom as an overhead product, whereas the hydrocarbon liquid and the particulates are withdrawn as a bottoms product. By feeding the liquid tangentially to the separator and maintaining a particulate-liquid slurry downward velocity of from about 0.01 to about 0.25 fps in the separator, a total solids weight percent in the slurry of from about 0.1 to about 30%, a slurry temperature of from about 550.degree. to about 900.degree. F., a slurry residence time in the separator of from about 30 to about 360 seconds, and a length/diameter ratio for the separator of from about 20/1 to about 50/1, so that the characterization factor, .alpha., defined as ##STR1## DOES NOT EXCEED ABOUT 48 (.degree.R sec.sup.2)/ft, the deposit of carbonaceous materials on the interior surface of the separator may be substantially eliminated.

  9. Nonlinear phased array imaging

    NASA Astrophysics Data System (ADS)

    Croxford, Anthony J.; Cheng, Jingwei; Potter, Jack N.

    2016-04-01

    A technique is presented for imaging acoustic nonlinearity within a specimen using ultrasonic phased arrays. Acoustic nonlinearity is measured by evaluating the difference in energy of the transmission bandwidth within the diffuse field produced through different focusing modes. The two different modes being classical beam forming, where delays are applied to different element of a phased array to physically focus the energy at a single location (parallel firing) and focusing in post processing, whereby one element at a time is fired and a focused image produced in post processing (sequential firing). Although these two approaches are linearly equivalent the difference in physical displacement within the specimen leads to differences in nonlinear effects. These differences are localized to the areas where the amplitude is different, essentially confining the differences to the focal point. Direct measurement at the focal point are however difficult to make. In order to measure this the diffuse field is used. It is a statistical property of the diffuse field that it represents the total energy in the system. If the energy in the diffuse field for both the sequential and parallel firing case is measured then the difference between these, within the input signal bandwidth, is largely due to differences at the focal spot. This difference therefore gives a localized measurement of where energy is moving out of the transmission bandwidth due to nonlinear effects. This technique is used to image fatigue cracks and other damage types undetectable with conventional linear ultrasonic measurements.

  10. A cosmic superfluid phase

    NASA Technical Reports Server (NTRS)

    Gradwohl, Ben-Ami

    1991-01-01

    The universe may have undergone a superfluid-like phase during its evolution, resulting from the injection of nontopological charge into the spontaneously broken vacuum. In the presence of vortices this charge is identified with angular momentum. This leads to turbulent domains on the scale of the correlation length. By restoring the symmetry at low temperatures, the vortices dissociate and push the charges to the boundaries of these domains. The model can be scaled (phenomenologically) to very low energies, it can be incorporated in a late time phase transition and form large scale structure in the boundary layers of the correlation volumes. The novel feature of the model lies in the fact that the dark matter is endowed with coherent motion. The possibilities of identifying this flow around superfluid vortices with the observed large scale bulk motion is discussed. If this identification is possible, then the definite prediction can be made that a more extended map of peculiar velocities would have to reveal large scale circulations in the flow pattern.

  11. Phase calibration target for quantitative phase imaging with ptychography.

    PubMed

    Godden, T M; Muñiz-Piniella, A; Claverley, J D; Yacoot, A; Humphry, M J

    2016-04-01

    Quantitative phase imaging (QPI) utilizes refractive index and thickness variations that lead to optical phase shifts. This gives contrast to images of transparent objects. In quantitative biology, phase images are used to accurately segment cells and calculate properties such as dry mass, volume and proliferation rate. The fidelity of the measured phase shifts is of critical importance in this field. However to date, there has been no standardized method for characterizing the performance of phase imaging systems. Consequently, there is an increasing need for protocols to test the performance of phase imaging systems using well-defined phase calibration and resolution targets. In this work, we present a candidate for a standardized phase resolution target, and measurement protocol for the determination of the transfer of spatial frequencies, and sensitivity of a phase imaging system. The target has been carefully designed to contain well-defined depth variations over a broadband range of spatial frequencies. In order to demonstrate the utility of the target, we measure quantitative phase images on a ptychographic microscope, and compare the measured optical phase shifts with Atomic Force Microscopy (AFM) topography maps and surface profile measurements from coherence scanning interferometry. The results show that ptychography has fully quantitative nanometer sensitivity in optical path differences over a broadband range of spatial frequencies for feature sizes ranging from micrometers to hundreds of micrometers. PMID:27137054

  12. Phase Detector For Rectangular Waveforms

    NASA Technical Reports Server (NTRS)

    Dischert, Robert A.; Walter, James M.

    1993-01-01

    Phase detector for use with phase-locked-loops, servocontrol, and other electronic circuits designed to avoid disadvantages of other phase detectors. Used with both intermittent and continuous input signals. Circuit offers several advantages; reference signals continuous, burst of few pulses, or single pulse. Circuit "coasts" in absence of reference signal. Generates no steady-state output waveform at lock which makes filtering easier.

  13. Phase-change materials handbook

    NASA Technical Reports Server (NTRS)

    Hale, D. V.; Hoover, M. J.; Oneill, M. J.

    1972-01-01

    Handbook describes relationship between phase-change materials and more conventional thermal control techniques and discusses materials' space and terrestrial applications. Material properties of most promising phase-change materials and purposes and uses of metallic filler materials in phase-change material composites are provided.

  14. Phase detector for three-phase power factor controller

    NASA Technical Reports Server (NTRS)

    Nola, F. J. (Inventor)

    1984-01-01

    A phase detector for the three phase power factor controller (PFC) is described. The phase detector for each phase includes an operational amplifier which senses the current phase angle for that phase by sensing the voltage across the phase thyristor. Common mode rejection is achieved by providing positive feedback between the input and output of the voltage sensing operational amplifier. this feedback preferably comprises a resistor connected between the output and input of the operational amplifier. The novelty of the invention resides in providing positive feedback such that switching of the operational amplifier is synchronized with switching of the voltage across the thyristor. The invention provides a solution to problems associated with high common mode voltage and enables use of lower cost components than would be required by other approaches.

  15. Phase coexistence far from equilibrium

    NASA Astrophysics Data System (ADS)

    Dickman, Ronald

    2016-04-01

    Investigation of simple far-from-equilibrium systems exhibiting phase separation leads to the conclusion that phase coexistence is not well defined in this context. This is because the properties of the coexisting nonequilibrium systems depend on how they are placed in contact, as verified in the driven lattice gas with attractive interactions, and in the two-temperature lattice gas, under (a) weak global exchange between uniform systems, and (b) phase-separated (nonuniform) systems. Thus, far from equilibrium, the notions of universality of phase coexistence (i.e., independence of how systems exchange particles and/or energy), and of phases with intrinsic properties (independent of their environment) are lost.

  16. Phase chaos in coupled oscillators.

    PubMed

    Popovych, Oleksandr V; Maistrenko, Yuri L; Tass, Peter A

    2005-06-01

    A complex high-dimensional chaotic behavior, phase chaos, is found in the finite-dimensional Kuramoto model of coupled phase oscillators. This type of chaos is characterized by half of the spectrum of Lyapunov exponents being positive and the Lyapunov dimension equaling almost the total system dimension. Intriguingly, the strongest phase chaos occurs for intermediate-size ensembles. Phase chaos is a common property of networks of oscillators of very different natures, such as phase oscillators, limit-cycle oscillators, and chaotic oscillators, e.g., Rössler systems. PMID:16089804

  17. Phase chaos in coupled oscillators

    NASA Astrophysics Data System (ADS)

    Popovych, Oleksandr V.; Maistrenko, Yuri L.; Tass, Peter A.

    2005-06-01

    A complex high-dimensional chaotic behavior, phase chaos, is found in the finite-dimensional Kuramoto model of coupled phase oscillators. This type of chaos is characterized by half of the spectrum of Lyapunov exponents being positive and the Lyapunov dimension equaling almost the total system dimension. Intriguingly, the strongest phase chaos occurs for intermediate-size ensembles. Phase chaos is a common property of networks of oscillators of very different natures, such as phase oscillators, limit-cycle oscillators, and chaotic oscillators, e.g., Rössler systems.

  18. Geometric phase shifting digital holography.

    PubMed

    Jackin, Boaz Jessie; Narayanamurthy, C S; Yatagai, Toyohiko

    2016-06-01

    A new phase shifting digital holographic technique using a purely geometric phase in Michelson interferometric geometry is proposed. The geometric phase in the system does not depend upon either optical path length or wavelength, unlike dynamic phase. The amount of geometric phase generated is controllable through a rotating wave plate. The new approach has unique features and major advantages in holographic measurement of transparent and reflecting three-dimensional (3D) objects. Experimental results on surface shape measurement and imaging of 3D objects are presented using the proposed method. PMID:27244436

  19. Phasing a segmented telescope

    NASA Astrophysics Data System (ADS)

    Paykin, Irina; Yacobi, Lee; Adler, Joan; Ribak, Erez N.

    2015-02-01

    A crucial part of segmented or multiple-aperture systems is control of the optical path difference between the segments or subapertures. In order to achieve optimal performance we have to phase subapertures to within a fraction of the wavelength, and this requires high accuracy of positioning for each subaperture. We present simulations and hardware realization of a simulated annealing algorithm in an active optical system with sparse segments. In order to align the optical system we applied the optimization algorithm to the image itself. The main advantage of this method over traditional correction methods is that wave-front-sensing hardware and software are no longer required, making the optical and mechanical system much simpler. The results of simulations and laboratory experiments demonstrate the ability of this optimization algorithm to correct both piston and tip-tilt errors.

  20. Multibeam Phased Array Antennas

    NASA Technical Reports Server (NTRS)

    Popovic, Zoya; Romisch, Stefania; Rondineau, Sebastien

    2004-01-01

    In this study, a new architecture for Ka-band multi-beam arrays was developed and demonstrated experimentally. The goal of the investigation was to demonstrate a new architecture that has the potential of reducing the cost as compared to standard expensive phased array technology. The goals of this specific part of the project, as stated in the yearly statement of work in the original proposal are: 1. Investigate bounds on performance of multi-beam lens arrays in terms of beamwidths, volume (size), isolation between beams, number of simultaneous beams, etc. 2. Design a small-scale array to demonstrate the principle. The array will be designed for operation around 3OGHz (Ka-band), with two 10-degree beamwidth beams. 3. Investigate most appropriate way to accomplish fine-tuning of the beam pointing within 5 degrees around the main beam pointing angle.

  1. Options Study - Phase II

    SciTech Connect

    R. Wigeland; T. Taiwo; M. Todosow; W. Halsey; J. Gehin

    2010-09-01

    The Options Study has been conducted for the purpose of evaluating the potential of alternative integrated nuclear fuel cycle options to favorably address the issues associated with a continuing or expanding use of nuclear power in the United States. The study produced information that can be used to inform decisions identifying potential directions for research and development on such fuel cycle options. An integrated nuclear fuel cycle option is defined in this study as including all aspects of the entire nuclear fuel cycle, from obtaining natural resources for fuel to the ultimate disposal of used nuclear fuel (UNF) or radioactive wastes. Issues such as nuclear waste management, especially the increasing inventory of used nuclear fuel, the current uncertainty about used fuel disposal, and the risk of nuclear weapons proliferation have contributed to the reluctance to expand the use of nuclear power, even though it is recognized that nuclear power is a safe and reliable method of producing electricity. In this Options Study, current, evolutionary, and revolutionary nuclear energy options were all considered, including the use of uranium and thorium, and both once-through and recycle approaches. Available information has been collected and reviewed in order to evaluate the ability of an option to clearly address the challenges associated with the current implementation and potential expansion of commercial nuclear power in the United States. This Options Study is a comprehensive consideration and review of fuel cycle and technology options, including those for disposal, and is not constrained by any limitations that may be imposed by economics, technical maturity, past policy, or speculated future conditions. This Phase II report is intended to be used in conjunction with the Phase I report, and much information in that report is not repeated here, although some information has been updated to reflect recent developments. The focus in this Options Study was to

  2. Phasing a segmented telescope.

    PubMed

    Paykin, Irina; Yacobi, Lee; Adler, Joan; Ribak, Erez N

    2015-02-01

    A crucial part of segmented or multiple-aperture systems is control of the optical path difference between the segments or subapertures. In order to achieve optimal performance we have to phase subapertures to within a fraction of the wavelength, and this requires high accuracy of positioning for each subaperture. We present simulations and hardware realization of a simulated annealing algorithm in an active optical system with sparse segments. In order to align the optical system we applied the optimization algorithm to the image itself. The main advantage of this method over traditional correction methods is that wave-front-sensing hardware and software are no longer required, making the optical and mechanical system much simpler. The results of simulations and laboratory experiments demonstrate the ability of this optimization algorithm to correct both piston and tip-tilt errors. PMID:25768631

  3. Infrared metamaterial phase holograms

    NASA Astrophysics Data System (ADS)

    Larouche, Stéphane; Tsai, Yu-Ju; Tyler, Talmage; Jokerst, Nan M.; Smith, David R.

    2012-05-01

    As a result of advances in nanotechnology and the burgeoning capabilities for fabricating materials with controlled nanoscale geometries, the traditional notion of what constitutes an optical device continues to evolve. The fusion of maturing low-cost lithographic techniques with newer optical design strategies has enabled the introduction of artificially structured metamaterials in place of conventional materials for improving optical components as well as realizing new optical functionality. Here we demonstrate multilayer, lithographically patterned, subwavelength, metal elements, whose distribution forms a computer-generated phase hologram in the infrared region (10.6 μm). Metal inclusions exhibit extremely large scattering and can be implemented in metamaterials that exhibit a wide range of effective medium response, including anomalously large or negative refractive index; optical magnetism; and controlled anisotropy. This large palette of metamaterial responses can be leveraged to achieve greater control over the propagation of light, leading to more compact, efficient and versatile optical components.

  4. Time domain phase measuring apparatus

    NASA Technical Reports Server (NTRS)

    Reinhardt, V. S. (Inventor)

    1978-01-01

    The phase and/or period stability of a device is determined by connecting the device in one orthogonal arm of a phase detector having a mixer. In the other arm is an adjustable, variable phase shift device. The output of the mixer is fed through an active low pass filter to derive a DC voltage indicative of the phase shift. The variable phase device is adjusted so that the DC voltage will nullify the phase shift of the tested device under normal conditions. The DC voltage level is converted into a time interval indicative of the phase change of the tested device by determining when the level equals the amplitude of a low frequency ramp voltage. The interval between adjacent equality points can be measured or the period between a reference point on the ramp voltage and the quality be measured.

  5. Phase Coarsening in Thin Films

    NASA Astrophysics Data System (ADS)

    Wang, K. G.; Glicksman, M. E.

    2015-08-01

    Phase coarsening (Ostwald ripening) phenomena are ubiquitous in materials growth processes such as thin film formation. The classical theory explaining late-stage phase coarsening phenomena was developed by Lifshitz and Slyozov, and by Wagner in the 1960s. Their theory is valid only for a vanishing volume fraction of the second phase in three dimensions. However, phase coarsening in two-dimensional systems is qualitatively different from that in three dimensions. In this paper, the many-body concept of screening length is reviewed, from which we derive the growth law for a `screened' phase island, and develop diffusion screening theory for phase coarsening in thin films. The coarsening rate constant, maximum size of phase islands in films, and their size distribution function will be derived from diffusion screening theory. A critical comparison will be provided of prior coarsening concepts and improvements derived from screening approaches.

  6. Degradation of C2-C15 volatile organic compounds in a landfill cover soil.

    PubMed

    Tassi, Franco; Montegrossi, Giordano; Vaselli, Orlando; Liccioli, Caterina; Moretti, Sandro; Nisi, Barbara

    2009-07-15

    The composition of non-methane volatile organic compounds (hereafter VOCs) in i) the cover soil, at depths of 30, 50 and 70 cm, and ii) gas recovery wells from Case Passerini landfill site, (Florence, Italy) was determined by GC-MS. The study, based on the analysis of interstitial gases sampled along vertical profiles within the cover soil, was aimed to investigate the VOC behaviour as biogas transits from a reducing to a relatively more oxidizing environment. A total of 48 and 63 different VOCs were identified in the soil and well gases, respectively. Aromatics represent the dominant group (71.5% of total VOC) in soil gases, followed by alkanes (6.8%), ketones (5.7%), organic acids (5.2%), aldehydes (3.0%), esters (2.6%), halogenated compounds (2.1%) and terpenes (1.3%). Cyclics, heterocyclics, S-bearing compounds and phenols are

  7. Preparation of 13C/15N-labeled oligomers using the polymerase chain reaction

    DOEpatents

    Chen, Xian; Gupta, Goutam; Bradbury, E. Morton

    2001-01-01

    Preparation of .sup.13 C/.sup.15 N-labeled DNA oligomers using the polymerase chain reaction (PCR). A PCR based method for uniform (.sup.13 C/.sup.15 N)-labeling of DNA duplexes is described. Multiple copies of a blunt-ended duplex are cloned into a plasmid, each copy containing the sequence of interest and restriction Hinc II sequences at both the 5' and 3' ends. PCR using bi-directional primers and uniformly .sup.13 C/.sup.15 N-labeled dNTP precursors generates labeled DNA duplexes containing multiple copies of the sequence of interest. Twenty-four cycles of PCR, followed by restriction and purification, gave the uniformly .sup.13 C/.sup.15 N-labeled duplex sequence with a 30% yield. Such labeled duplexes find significant applications in multinuclear magnetic resonance spectroscopy.

  8. Tri3, Which Controls Trichothecene C-15 Acetylation, is Functional in 3ADON Chemotype

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Three different trichothecene chemotypes have been identified in U.S. strains of Fusarium graminearum: 3-acetyldeoxynivalenol (3ADON), 15-acetyldeoxynivalenol (15ADON), and nivalenol (NIV), although grain is typically contaminated with deoxynivalenol (DON) or nivalenol rather than the acetylated ...

  9. Nuclear magnetic resonance data of C15H23AsS2

    NASA Astrophysics Data System (ADS)

    Mikhova, B. M.

    This document is part of Part 6 `Organic Metalloid Compounds' of Subvolume D 'Chemical Shifts and Coupling Constants for Carbon-13' of Landolt-Börnstein III/35 'Nuclear Magnetic Resonance Data', Group III 'Condensed Matter'.

  10. Materials Data on C15S4 (SG:15) by Materials Project

    SciTech Connect

    Kristin Persson

    2014-11-02

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  11. Simulation of Mission Phases

    NASA Technical Reports Server (NTRS)

    Carlstrom, Nicholas Mercury

    2016-01-01

    This position with the Simulation and Graphics Branch (ER7) at Johnson Space Center (JSC) provided an introduction to vehicle hardware, mission planning, and simulation design. ER7 supports engineering analysis and flight crew training by providing high-fidelity, real-time graphical simulations in the Systems Engineering Simulator (SES) lab. The primary project assigned by NASA mentor and SES lab manager, Meghan Daley, was to develop a graphical simulation of the rendezvous, proximity operations, and docking (RPOD) phases of flight. The simulation is to include a generic crew/cargo transportation vehicle and a target object in low-Earth orbit (LEO). Various capsule, winged, and lifting body vehicles as well as historical RPOD methods were evaluated during the project analysis phase. JSC core mission to support the International Space Station (ISS), Commercial Crew Program (CCP), and Human Space Flight (HSF) influenced the project specifications. The simulation is characterized as a 30 meter +V Bar and/or -R Bar approach to the target object's docking station. The ISS was selected as the target object and the international Low Impact Docking System (iLIDS) was selected as the docking mechanism. The location of the target object's docking station corresponds with the RPOD methods identified. The simulation design focuses on Guidance, Navigation, and Control (GNC) system architecture models with station keeping and telemetry data processing capabilities. The optical and inertial sensors, reaction control system thrusters, and the docking mechanism selected were based on CCP vehicle manufacturer's current and proposed technologies. A significant amount of independent study and tutorial completion was required for this project. Multiple primary source materials were accessed using the NASA Technical Report Server (NTRS) and reference textbooks were borrowed from the JSC Main Library and International Space Station Library. The Trick Simulation Environment and User

  12. Phase-shifting point diffraction interferometer phase grating designs

    DOEpatents

    Naulleau, Patrick

    2001-01-01

    Diffraction phase gratings are employed in phase-shifting point diffraction interferometers to improve the interferometric fringe contrast. The diffraction phase grating diffracts a zeroth-order diffraction of light at a first power level to the test-beam window of a mask that is positioned at the image plane and a first-order diffraction at a second power to the reference-beam pinhole. The diffraction phase grating is preferably selected to yield a desired ratio of the first power level to second power level.

  13. Phased Array Feeds

    NASA Astrophysics Data System (ADS)

    Fisher, J. Richard; Bradley, Richard F.; Brisken, Walter F.; Cotton, William D.; Emerson, Darrel T.; Kerr, Anthony R.; Lacasse, Richard J.; Morgan, Matthew A.; Napier, Peter J.; Norrod, Roger D.; Payne, John M.; Pospieszalski, Marian W.; Symmes, Arthur; Thompson, A. Richard; Webber, John C.

    This white paper offers cautionary observations about the planning and development of new, large radio astronomy instruments. Complexity is a strong cost driver so every effort should be made to assign differing science requirements to different instruments and probably different sites. The appeal of shared resources is generally not realized in practice and can often be counterproductive. Instrument optimization is much more difficult with longer lists of requirements, and the development process is longer and less efficient. More complex instruments are necessarily further behind the technology state of the art because of longer development times. Including technology R&D in the construction phase of projects is a growing trend that leads to higher risks, cost overruns, schedule delays, and project de-scoping. There are no technology breakthroughs just over the horizon that will suddenly bring down the cost of collecting area. Advances come largely through careful attention to detail in the adoption of new technology provided by industry and the commercial market. Radio astronomy instrumentation has a very bright future, but a vigorous long-term R&D program not tied directly to specific projects needs to be restored, fostered, and preserved.

  14. Optimal Phase Oscillatory Network

    NASA Astrophysics Data System (ADS)

    Follmann, Rosangela

    2013-03-01

    Important topics as preventive detection of epidemics, collective self-organization, information flow and systemic robustness in clusters are typical examples of processes that can be studied in the context of the theory of complex networks. It is an emerging theory in a field, which has recently attracted much interest, involving the synchronization of dynamical systems associated to nodes, or vertices, of the network. Studies have shown that synchronization in oscillatory networks depends not only on the individual dynamics of each element, but also on the combination of the topology of the connections as well as on the properties of the interactions of these elements. Moreover, the response of the network to small damages, caused at strategic points, can enhance the global performance of the whole network. In this presentation we explore an optimal phase oscillatory network altered by an additional term in the coupling function. The application to associative-memory network shows improvement on the correct information retrieval as well as increase of the storage capacity. The inclusion of some small deviations on the nodes, when solutions are attracted to a false state, results in additional enhancement of the performance of the associative-memory network. Supported by FAPESP - Sao Paulo Research Foundation, grant number 2012/12555-4

  15. Impulsive phase transport

    NASA Technical Reports Server (NTRS)

    Canfield, Richard C.; Bely-Dubau, Francoise; Brown, John C.; Dulk, George A.; Emslie, A. Gordon; Enome, Shinzo; Gabriel, Alan H.; Kundu, Mukul R.; Melrose, Donald; Neidig, Donald F.

    1986-01-01

    The transport of nonthermal electrons is explored. The thick-target electron beam model, in which electrons are presumed to be accelerated in the corona and typically thermalized primarily in the chromosphere and photosphere, is supported by observations throughout the electromagnetic spectrum. At the highest energies, the anisotropy of gamma-ray emission above 10 MeV clearly indicates that these photons are emitted by anisotropically-directed particles. The timing of this high-energy gamma-radiation with respect to lower-energy hard X-radiation implies that the energetic particles have short life-times. For collisional energy loss, this means that they are stopped in the chromosphere or below. Stereoscopic (two-spacecraft) observations at hard X-ray energies (up to 350 keV) imply that these lower-energy (but certainly nonthermal) electrons are also stopped deep in the chromosphere. Hard X-ray images show that, in spatially resolved flares whose radiation consists of impulsive bursts, the impulsive phase starts with X-radiation that comes mostly from the foot-points of coronal loops whose coronal component is outlined by microwaves.

  16. Phase change materials handbook

    NASA Technical Reports Server (NTRS)

    Hale, D. V.; Hoover, M. J.; Oneill, M. J.

    1971-01-01

    This handbook is intended to provide theory and data needed by the thermal design engineer to bridge the gap between research achievements and actual flight systems, within the limits of the current state of the art of phase change materials (PCM) technology. The relationship between PCM and more conventional thermal control techniques is described and numerous space and terrestrial applications of PCM are discussed. Material properties of the most promising PCMs are provided; the purposes and use of metallic filler materials in PCM composites are presented; and material compatibility considerations relevant to PCM design are included. The engineering considerations of PCM design are described, especially those pertaining to the thermodynamic and heat transfer phenomena peculiar to PCM design. Methods of obtaining data not currently available are presented. The special problems encountered in the space environment are described. Computational tools useful to the designer are discussed. In summary, each aspect of the PCM problem important to the design engineer is covered to the extent allowed by the scope of this effort and the state of the art.

  17. Long-Term Phase Instability in Water-Quenched U-6Nb

    SciTech Connect

    Hsiung, L L; Zhou, J

    2006-01-16

    A combinative approach of microhardness testing, tensile testing, and TEM microstructural analysis was employed to study the microstructure and mechanical instability of a water-quenched U-6wt.% Nb (WQ-U6Nb) alloy subjected to different aging schedules including artificial aging at 200 C, 15-year natural aging at ambient temperatures, and 15-year natural aging followed by accelerative aging at 200 C. The changes in mechanical property during and after the aging processes were examined using microhardness and tensile-testing methods. During the early stages of artificial aging at 200 C, the microhardness of WQ-U6Nb alloy increased, i.e., age hardening, as a result of the development of nanoscale modulation caused by spinodal decomposition. Coarsening of the modulated structure occurred after a prolonged aging at 200 C for 16 hours, and it led to a decrease of microhardness, i.e., age softening. Phase instability was also found to occur in WQ-U6Nb alloy that was subjected to a 15-year natural aging at ambient temperatures. The formation of partially ordered domains resulting from a spinodal modulation with an atomic-scale wavelength rendered the appearance of swirl-shape antiphase domain boundaries (APBs) observed in TEM images. Although it did not cause a significant change in microhardness, 15-year natural aging has dramatically affected the aging mechanisms of the alloy isothermally aged at 200 C. Microhardness values of the NA alloy continuously increased after isothermal aging at 200 C for 96 hours as a result of the phase decomposition of partially ordered domains into Nb-depleted {alpha} phase and Nb-enriched U{sub 3}Nb ordered phase in the alloy. It is concluded that the long-term natural aging changes the transformation sequence of WQ-U6Nb, and it leads to order-disorder transformation, precipitation hardening, and ductility embrittlement of WQ-U6Nb alloy.

  18. Phase contrast without phase plates and phase rings--optical solutions for improved imaging of phase structures.

    PubMed

    Piper, Timm; Piper, Jörg

    2013-10-01

    Using the optical methods described, phase specimens can be observed with a modified light microscope in enhanced clarity, purified from typical artifacts which are apparent in standard phase contrast illumination. In particular, haloing and shade-off are absent, lateral and vertical resolution are maximized and the image quality remains constant even in problematic preparations which cannot be well examined in normal phase contrast, such as specimens beyond a critical thickness or covered by obliquely situated cover slips. The background brightness and thus the range of contrast can be continuously modulated and specimens can be illuminated in concentric-peripheral, axial or paraxial light. Additional contrast effects can be achieved by spectral color separation. Normal glass or mirror lenses can be used; they do not need to be fitted with a phase plate or a phase ring. The methods described should be of general interest for all disciplines using phase microscopy. PMID:23913620

  19. Phase-Oriented Gear Systems

    NASA Technical Reports Server (NTRS)

    Vranish, John M.

    2007-01-01

    Phase-oriented gear systems are differential planetary transmissions in which each planet gear has two sets of unequal numbers of teeth indexed at prescribed relative angles (phases). The figure illustrates an application of the phase-oriented gearing concept to a relatively simple speed-reducing differential planetary transmission that includes a sun gear, an idler gear, three identical planet gears, a ground internal ring gear, and an output internal ring gear. Typically, the ground internal ring gear and output internal ring gear have different numbers of teeth, giving rise to a progressive and periodic phase shift between the corresponding pairs of teeth engaged by each successive planet gear. To accommodate this phase shift, it is necessary to introduce a compensating phase shift between the ground-gear-engaging and output-gearengaging sections of each planet gear. This is done by individually orienting each planet gear

  20. Distributed phased array architecture study

    NASA Technical Reports Server (NTRS)

    Bourgeois, Brian

    1987-01-01

    Variations in amplifiers and phase shifters can cause degraded antenna performance, depending also on the environmental conditions and antenna array architecture. The implementation of distributed phased array hardware was studied with the aid of the DISTAR computer program as a simulation tool. This simulation provides guidance in hardware simulation. Both hard and soft failures of the amplifiers in the T/R modules are modeled. Hard failures are catastrophic: no power is transmitted to the antenna elements. Noncatastrophic or soft failures are modeled as a modified Gaussian distribution. The resulting amplitude characteristics then determine the array excitation coefficients. The phase characteristics take on a uniform distribution. Pattern characteristics such as antenna gain, half power beamwidth, mainbeam phase errors, sidelobe levels, and beam pointing errors were studied as functions of amplifier and phase shifter variations. General specifications for amplifier and phase shifter tolerances in various architecture configurations for C band and S band were determined.

  1. Oscillatory phase shapes syllable perception.

    PubMed

    Ten Oever, Sanne; Sack, Alexander T

    2015-12-29

    The role of oscillatory phase for perceptual and cognitive processes is being increasingly acknowledged. To date, little is known about the direct role of phase in categorical perception. Here we show in two separate experiments that the identification of ambiguous syllables that can either be perceived as /da/ or /ga/ is biased by the underlying oscillatory phase as measured with EEG and sensory entrainment to rhythmic stimuli. The measured phase difference in which perception is biased toward /da/ or /ga/ exactly matched the different temporal onset delays in natural audiovisual speech between mouth movements and speech sounds, which last 80 ms longer for /ga/ than for /da/. These results indicate the functional relationship between prestimulus phase and syllable identification, and signify that the origin of this phase relationship could lie in exposure and subsequent learning of unique audiovisual temporal onset differences. PMID:26668393

  2. Theory of antiferroelectric phase transitions

    NASA Astrophysics Data System (ADS)

    Tolédano, Pierre; Guennou, Mael

    2016-07-01

    At variance with structural ferroic phase transitions which give rise to macroscopic tensors coupled to macroscopic fields, criteria defining antiferroelectric (AFE) phase transitions are still under discussion due to the absence of specific symmetry properties characterizing their existence. They are recognized by the proximity of a ferroelectric (FE) phase induced under applied electric field, with a double hysteresis loop relating the induced polarization to the electric field and a typical anomaly of the dielectric permittivity. Here, we show that there exist indeed symmetry criteria defining AFE transitions. They relate the local symmetry of the polar crystallographic sites emerging at an AFE phase transition with the macroscopic symmetry of the AFE phase. The dielectric properties of AFE transitions are deduced from a Landau theoretical model in which ferroelectric and ferrielectric phases are shown to stabilize as the result of specific symmetry-allowed couplings of the AFE order parameter with the field-induced polarization.

  3. Berry phase in neutrino oscillations

    SciTech Connect

    He Xiaogang; McKellar, Bruce H.J.; Zhang Yue

    2005-09-01

    We study the Berry phase in neutrino oscillations for both Dirac and Majorana neutrinos. In order to have a Berry phase, the neutrino oscillations must occur in a varying medium, the neutrino-background interactions must depend on at least two independent densities, and also there must be CP violation. If the neutrino interactions with matter are mediated only by the standard model W and Z boson exchanges, these conditions imply that there must be at least three generations of neutrinos. The CP violating Majorana phases do not play a role in generating a Berry phase. We show that a natural way to satisfy the conditions for the generation of a Berry phase is to have sterile neutrinos with active-sterile neutrino mixing, in which case at least two active and one sterile neutrinos are required. If there are additional new CP violating flavor changing interactions, it is also possible to have a nonzero Berry phase with just two generations.

  4. Digitally controlled distributed phase shifter

    SciTech Connect

    Hietala, V.M.; Kravitz, S.H.; Vawter, G.A.

    1992-12-31

    A digitally controlled distributed phase shifter is comprised of N phase shifters. Digital control is achieved by using N binary length-weighted electrodes located on the top surface of a waveguide. A control terminal is attached to each electrode thereby allowing the application of a control signal. The control signal is either one of two discrete bias voltages. The application of the discrete bias voltages change the modal index of a portion of the waveguide that corresponds to a length of the electrode to which the bias voltage is applied, thereby causing the phase to change through the underlying portion of the waveguide. The digitally controlled distributed phase shift network has a total phase shift comprised of the sum of the individual phase shifters.

  5. Phase structure of soliton molecules

    SciTech Connect

    Hause, A.; Hartwig, H.; Seifert, B.; Stolz, H.; Boehm, M.; Mitschke, F.

    2007-06-15

    Temporal optical soliton molecules were recently demonstrated; they potentially allow further increase of data rates in optical telecommunication. Their binding mechanism relies on the internal phases, but these have not been experimentally accessible so far. Conventional frequency-resolved optical gating techniques are not suited for measurement of their phase profile: Their algorithms fail to converge due to zeros both in their temporal and their spectral profile. We show that the VAMPIRE (very advanced method of phase and intensity retrieval of E-fields) method performs reliably. With VAMPIRE the phase profile of soliton molecules has been measured, and further insight into the mechanism is obtained.

  6. Phase structure of soliton molecules

    NASA Astrophysics Data System (ADS)

    Hause, A.; Hartwig, H.; Seifert, B.; Stolz, H.; Böhm, M.; Mitschke, F.

    2007-06-01

    Temporal optical soliton molecules were recently demonstrated; they potentially allow further increase of data rates in optical telecommunication. Their binding mechanism relies on the internal phases, but these have not been experimentally accessible so far. Conventional frequency-resolved optical gating techniques are not suited for measurement of their phase profile: Their algorithms fail to converge due to zeros both in their temporal and their spectral profile. We show that the VAMPIRE (very advanced method of phase and intensity retrieval of E -fields) method performs reliably. With VAMPIRE the phase profile of soliton molecules has been measured, and further insight into the mechanism is obtained.

  7. Fluctuation driven electroweak phase transition

    NASA Technical Reports Server (NTRS)

    Gleiser, Marcelo; Kolb, Edward W.

    1991-01-01

    We examine the dynamics of the electroweak phase transition in the early Universe. For Higgs masses in the range 46 less than or = M sub H less than or = 150 GeV and top quark masses less than 200 GeV, regions of symmetric and asymmetric vacuum coexist to below the critical temperature, with thermal equilibrium between the two phases maintained by fluctuations of both phases. We propose that the transition to the asymmetric vacuum is completed by percolation of these subcritical fluctuations. Our results are relevant to scenarios of baryogenesis that invoke a weakly first-order phase transition at the electroweak scale.

  8. Going through a quantum phase

    NASA Technical Reports Server (NTRS)

    Shapiro, Jeffrey H.

    1992-01-01

    Phase measurements on a single-mode radiation field are examined from a system-theoretic viewpoint. Quantum estimation theory is used to establish the primacy of the Susskind-Glogower (SG) phase operator; its phase eigenkets generate the probability operator measure (POM) for maximum likelihood phase estimation. A commuting observables description for the SG-POM on a signal x apparatus state space is derived. It is analogous to the signal-band x image-band formulation for optical heterodyne detection. Because heterodyning realizes the annihilation operator POM, this analogy may help realize the SG-POM. The wave function representation associated with the SG POM is then used to prove the duality between the phase measurement and the number operator measurement, from which a number-phase uncertainty principle is obtained, via Fourier theory, without recourse to linearization. Fourier theory is also employed to establish the principle of number-ket causality, leading to a Paley-Wiener condition that must be satisfied by the phase-measurement probability density function (PDF) for a single-mode field in an arbitrary quantum state. Finally, a two-mode phase measurement is shown to afford phase-conjugate quantum communication at zero error probability with finite average photon number. Application of this construct to interferometric precision measurements is briefly discussed.

  9. Topological phases of eternal inflation

    SciTech Connect

    Sekino, Yasuhiro; Shenker, Stephen; Susskind, Leonard

    2010-06-15

    ''Eternal inflation'' is a term that describes a number of different phenomena that have been classified by Winitzki. According to Winitzki's classification, these phases can be characterized by the topology of the percolating structures in the inflating, 'white', region. In this paper we discuss these phases, the transitions between them, and the way they are seen by a 'Census Taker', a hypothetical observer inside the noninflating, 'black', region. We discuss three phases that we call 'black island', 'tubular', and 'white island'. The black island phase is familiar, composed of rare Coleman De Luccia bubble nucleation events. The Census Taker sees an essentially spherical boundary, described by the conformal field theory of the Friedmann-Robertson-Walker/conformal field theory (FRW/CFT) correspondence. In the tubular phase the Census Taker sees a complicated infinite genus structure composed of arbitrarily long tubes. The white island phase is even more mysterious from the black side. Surprisingly, when viewed from the noninflating region this phase resembles a closed, positively curved universe that eventually collapses to a singularity. Nevertheless, pockets of eternal inflation continue forever. In addition, there is an 'aborted' phase in which no eternal inflation takes place. Rigorous results of Chayes, Chayes, Grannan, and Swindle establish the existence of all of these phases, separated by first order transitions, in Mandelbrot percolation, a simple model of eternal inflation.

  10. Logistics planning for phased programs.

    NASA Technical Reports Server (NTRS)

    Cook, W. H.

    1973-01-01

    It is pointed out that the proper and early integration of logistics planning into the phased program planning process will drastically reduce these logistics costs. Phased project planning is a phased approach to the planning, approval, and conduct of major research and development activity. A progressive build-up of knowledge of all aspects of the program is provided. Elements of logistics are discussed together with aspects of integrated logistics support, logistics program planning, and logistics activities for phased programs. Continuing logistics support can only be assured if there is a comprehensive sequential listing of all logistics activities tied to the program schedule and a real-time inventory of assets.

  11. Emittance and Phase Space Exchange

    SciTech Connect

    Xiang, Dao; Chao, Alex; /SLAC

    2011-08-19

    Alternative chicane-type beam lines are proposed for exact emittance exchange between horizontal phase space (x; x{prime}) and longitudinal phase space (z; {delta}). Methods to achieve exact phase space exchanges, i.e. mapping x to z, x{prime} to {delta}, z to x and {delta} to x{prime} are suggested. Methods to mitigate the thick-lens effect of the transverse cavity on emittance exchange are discussed. Some applications of the phase space exchanger and the feasibility of an emittance exchange experiment with the proposed chicane-type beam line at SLAC are discussed.

  12. Phase characteristics of electromagnetic stirring

    SciTech Connect

    Fujisaki, Keisuke; Ueyama, Takatsugu; Takahashi, Keiichi; Satoh, Shouji

    1997-09-01

    Electromagnetic stirring is used at billet molds as well as at slab mold, to get high quality steel at continuous casting in steel making plant. In order to get the same electromagnetic force in each billet mold and thus the same quality, phase characteristics of electromagnetic stirring is investigated. From the calculation result, it is found that the relative phase at which the difference of the electromagnetic torque in each mold becomes the smallest is 0 or 240 deg. To apply the phase characteristics of the EMS to the quality control, the authors propose the dynamic phase control system by two inverters to get the high quality in the surface crack.

  13. Quantum phase transition in space

    SciTech Connect

    Damski, Bogdan; Zurek, Wojciech H

    2008-01-01

    A quantum phase transition between the symmetric (polar) phase and the phase with broken symmetry can be induced in a ferromagnetic spin-1 Bose-Einstein condensate in space (rather than in time). We consider such a phase transition and show that the transition region in the vicinity of the critical point exhibits scalings that reflect a compromise between the rate at which the transition is imposed (i.e., the gradient of the control parameter) and the scaling of the divergent healing length in the critical region. Our results suggest a method for the direct measurement of the scaling exponent {nu}.

  14. Method for aqueous phase reactions

    DOEpatents

    Elliott, Douglas C.; Hart, Todd R.

    2000-01-01

    A method for converting liquid organic material in a mixture into a product utilizing a catalyst in the form of a plurality of porous particles wherein each particle is a support having nickel metal catalytic phase or reduced nickel deposited thereon in a first dispersed phase and an additional metal deposited onto the support in a second dispersed phase. The additional metal is effective in retarding or reducing agglomeration or sintering of the nickel metal catalytic phase without substantially affecting the catalytic activity, thereby increasing the life time of the catalyst.

  15. Invalid phase values removal method for absolute phase recovery.

    PubMed

    Lu, Jin; Mo, Rong; Sun, Huibin; Chang, Zhiyong; Zhao, Xiaxia

    2016-01-10

    A novel approach is presented for more effectively removing invalid phase values in absolute phase recovery. The approach is based on a detailed study involving the types and cases of invalid phase values. Meanwhile, some commonalities of the existing removal algorithms also are thoroughly analyzed. It is well known that rough absolute phase and fringe order maps can very easily be obtained by temporal phase unwrapping techniques. After carefully analyzing the components and fringe order distribution of the rough fringe order map, the proposed method chiefly adopts an entirely new strategy to refine a pure fringe order map. The strategy consists of three parts: (1) the square of an image gradient, (2) subregion areas of the binary image, and (3) image decomposition and composition. In combination with the pure fringe order map and a removal criterion, the invalid phase values can be identified and filtered out from the rough absolute phase map. This new strategy not only gets rid of the limitations of traditional removal methods but also has a two-fold function. The paper also offers different metrics from the experiment to evaluate the quality of the final absolute phase. In contrast with other removal methods, experimental results have verified the feasibility, effectiveness, and superiority of the proposed method. PMID:26835776

  16. Quantitative Phase Microscopy: how to make phase data meaningful.

    PubMed

    Goldstein, Goldie; Creath, Katherine

    2014-03-12

    The continued development of hardware and associated image processing techniques for quantitative phase microscopy has allowed superior phase data to be acquired that readily shows dynamic optical volume changes and enables particle tracking. Recent efforts have focused on tying phase data and associated metrics to cell morphology. One challenge in measuring biological objects using interferometrically obtained phase information is achieving consistent phase unwrapping and -dimensions and correct for temporal discrepanices using a temporal unwrapping procedure. The residual background shape due to mean value fluctuations and residual tilts can be removed automatically using a simple object characterization algorithm. Once the phase data are processed consistently, it is then possible to characterize biological samples such as myocytes and myoblasts in terms of their size, texture and optical volume and track those features dynamically. By observing optical volume dynamically it is possible to determine the presence of objects such as vesicles within myoblasts even when they are co-located with other objects. Quantitative phase microscopy provides a label-free mechanism to characterize living cells and their morphology in dynamic environments, however it is critical to connect the measured phase to important biological function for this measurement modality to prove useful to a broader scientific community. In order to do so, results must be highly consistent and require little to no user manipulation to achieve high quality nynerical results that can be combined with other imaging modalities. PMID:25309099

  17. PHASE CHANGE LIQUIDS

    SciTech Connect

    Susan S. Sorini; John F. Schabron

    2006-03-01

    Work is being performed to develop a new shipping system for frozen environmental samples (or other materials) that uses an optimal phase change liquid (PCL) formulation and an insulated shipping container with an on-board digital temperature data logger to provide a history of the temperature profile within the container during shipment. In previous work, several PCL formulations with temperatures of fusion ranging from approximately -14 to -20 C were prepared and evaluated. Both temperature of fusion and heat of fusion of the formulations were measured, and an optimal PCL formulation was selected. The PCL was frozen in plastic bags and tested for its temperature profile in a cooler using a digital temperature data logger. This testing showed that the PCL formulation can maintain freezer temperatures (< -7 to -20 C) for an extended period, such as the time for shipping samples by overnight courier. The results of the experiments described in this report provide significant information for use in developing an integrated freezer system that uses a PCL formulation to maintain freezer temperatures in coolers for shipping environmental samples to the laboratory. Experimental results show the importance of the type of cooler used in the system and that use of an insulating material within the cooler improves the performance of the freezer system. A new optimal PCL formulation for use in the system has been determined. The new formulation has been shown to maintain temperatures at < -7 to -20 C for 47 hours in an insulated cooler system containing soil samples. These results are very promising for developing the new technology.

  18. Adaptive Phase Delay Generator

    NASA Technical Reports Server (NTRS)

    Greer, Lawrence

    2013-01-01

    There are several experimental setups involving rotating machinery that require some form of synchronization. The adaptive phase delay generator (APDG) the Bencic-1000 is a flexible instrument that allows the user to generate pulses synchronized to the rising edge of a tachometer signal from any piece of rotating machinery. These synchronized pulses can vary by the delay angle, pulse width, number of pulses per period, number of skipped pulses, and total number of pulses. Due to the design of the pulse generator, any and all of these parameters can be changed independently, yielding an unparalleled level of versatility. There are two user interfaces to the APDG. The first is a LabVIEW program that has the advantage of displaying all of the pulse parameters and input signal data within one neatly organized window on the PC monitor. Furthermore, the LabVIEW interface plots the rpm of the two input signal channels in real time. The second user interface is a handheld portable device that goes anywhere a computer is not accessible. It consists of a liquid-crystal display and keypad, which enable the user to control the unit by scrolling through a host of command menus and parameter listings. The APDG combines all of the desired synchronization control into one unit. The experimenter can adjust the delay, pulse width, pulse count, number of skipped pulses, and produce a specified number of pulses per revolution. Each of these parameters can be changed independently, providing an unparalleled level of versatility when synchronizing hardware to a host of rotating machinery. The APDG allows experimenters to set up quickly and generate a host of synchronizing configurations using a simple user interface, which hopefully leads to faster results.

  19. Topology in Ordered Phases

    NASA Astrophysics Data System (ADS)

    Tanda, Satoshi; Matsuyama, Toyoki; Oda, Migaku; Asano, Yasuhiro; Yakubo, Kousuke

    2006-08-01

    .]. Nanofibers of hydrogen storage alloy / I. Saita ... [et al.]. Synthesis of stable icosahedral quasicrystals in Zn-Sc based alloys and their magnetic properties / S. Kashimoto and T. Ishimasa. One-armed spiral wave excited by eam pressure in accretion disks in Be/X-Ray binaries / K. Hayasaki and A. T. Okazaki -- IV. Topological defects and excitations. Topological excitations in the ground state of charge density wave systems / P. Monceau. Soliton transport in nanoscale charge-density-wave systems / K. Inagaki, T. Toshima and S. Tanda. Topological defects in triplet superconductors UPt3, Sr[symbol]RuO[symbol], etc. / K. Maki ... [et al.]. Microscopic structure of vortices in type II superconductors / K. Machida ... [et al.]. Microscopic neutron investigation of the Abrikosov state of high-temperature superconductors / J. Mesot. Energy dissipation at nano-scale topological defects of high-Tc superconductors: microwave study / A. Maeda. Pressure induced topological phase transition in the heavy Fermion compound CeAl[symbol] / H. Miyagawa ... [et al.]. Explanation for the unusual orientation of LSCO square vortex lattice in terms of nodal superconductivity / M. Oda. Local electronic states in Bi[symbol]Sr[symbol]CaCu[symbol]O[symbol] / A. Hashimoto ... [et al.] -- V. Topology in quantum phenomena. Topological vortex formation in a Bose-Einstein condensate of alkali-metal atoms / M. Nakahara. Quantum phase transition of [symbol]He confined in nano-porous media / K. Shirahama, K. Yamamoto and Y. Shibayama. A new mean-field theory for Bose-Einstein condensates / T. Kita. Spin current in topological cristals / Y. Asano. Antiferromagnetic defects in non-magnetic hidden order of the heavy-electron system URu[symbol]Si[symbol] / H. Amitsuka, K. Tenya and M. Yokoyama. Magnetic-field dependences of thermodynamic quantities in the vortex state of Type-II superconductors / K. Watanabe, T. Kita and M. Arai. Three-magnon-mediated nuclear spin relaxation in quantum ferrimagnets of topological

  20. Phase noise measurement of phase modulation microwave photonic links

    NASA Astrophysics Data System (ADS)

    Ye, Quanyi; Chen, Zhengyu; Xu, Zhiguo; Gao, Yingjie

    2015-10-01

    Microwave photonic links (MPLs) can provide many advantages over traditional coaxial and waveguide solutions due to its low loss, small size, lightweight, large bandwidth, superior stability and immunity to external interference. It has been considered in various applications such as: the transmission of radio frequency (RF) signal over optical carriers, video television transmission, radar and communication systems. Stability of phase of the microwave photonic links is a critical issue in several realistic applications. The delay line technique for phase noise measurement of phase modulation microwave photonic links is measured for the first time. Using this approach, the input signal noise and power supply noise can be effectively cancelled, and it does not require phase locking. The phase noise of a microwave photonic links with a 10 GHz sinusoidal signal is experimentally demonstrated.

  1. Phase-locked loop with controlled phase slippage

    DOEpatents

    Mestha, L.K.

    1994-03-29

    A system for synchronizing a first subsystem controlled by a changing frequency sweeping from a first frequency to a second frequency, with a second subsystem operating at a steady state second frequency is described. Trip plan parameters are calculated in advance to determine the phase relationship between the frequencies of the first subsystem and second subsystem in order to obtain synchronism at the end of the frequency sweep of the first subsystem. During the time in which the frequency of the first subsystem is sweeping from the first frequency to the second frequency, the phase locked system compares the actual phase difference with the trip plan phase difference and incrementally changes the sweep frequency in a manner so that phase lock is achieved when the first subsystem reaches a frequency substantially identical to that of the second subsystem. 10 figures.

  2. Phase-locked loop with controlled phase slippage

    SciTech Connect

    Mestha, Lingappa K.

    1994-01-01

    A system for synchronizing a first subsystem controlled by a changing frequency sweeping from a first frequency to a second frequency, with a second subsystem operating at a steady state second frequency. Trip plan parameters are calculated in advance to determine the phase relationship between the frequencies of the first subsystem and second subsystem in order to obtain synchronism at the end of the frequency sweep of the first subsystem. During the time in which the frequency of the first subsystem is sweeping from the first frequency to the second frequency, the phase locked system compares the actual phase difference with the trip plan phase difference and incrementally changes the sweep frequency in a manner so that phase lock is achieved when the first subsystem reaches a frequency substantially identical to that of the second subsystem.

  3. Superconductivity and Phase Separation in Oxygenated LANTHANUM(2-X) Strontium(x) Copper OXYGEN(4+DELTA)

    NASA Astrophysics Data System (ADS)

    Feng, Hung-Hsu

    1995-01-01

    In spite of the intensive, world-wide study of high temperature superconductors since their discovery ten years ago, the understanding of the microscopic mechanism of high temperature superconductivity is still limited. Phenomenologically, the hole concentration (P) is the most important parameter for manipulating the superconducting properties. Various physical properties have been established in terms of P to search for universal behaviors among the high-T_{c} cuprates. Recently, the phenomenon of clustering of holes in real space has been investigated for the high-T_ {c} cuprates, experimentally and theoretically. The realization of clustering of holes in the high- T_{c} cuprates will provide a new concept of the underlying electronic structure in them. In this work, we have studied the physical properties and behavior of phase separation for oxygenated rm La_{2-x}Sr_{x}CuO _{4+delta} (x = 0, 0.05; 0 < delta < 0.12), and compared the results to that of cation doped La_ {2-x}M_{x}CuO_4. We have, for the first time, synthesized two series of La_2CuO_{4+delta } (0 < delta < 0.12) and La_{1.95}Sr_{0.05 }CuO_{4+delta} (0 < delta <= 0.05) exhibiting consistent and reproducible physical properties. The results of this study show the following: (1) An anomalous electronic state with T_{c} ~ 15 K corresponding to P ~ 0.125 is found in both oxygenated La_2CuO _{4+delta} and La_{1.95}Sr_{0.05}CuO _{4+delta} systems. This indicates that all the T_{c } anomalies observed in cation doped La_{2-x}M_{x}CuO _4 and anion doped La_2CuO _{4+delta} are electronically driven and are of a common origin. (2) A two-superconducting phase region, T_{c} ~ 15 K and ~ 32 K, is found both in oxygenated La_2CuO _{4+delta} and La_{1.95}Sr_{0.05}CuO _{4+delta} in the same hole concentration range (P > 0.1) but in different oxygen concentration ranges. This indicates that the phase separation is electronically driven. (3) A universal physical picture in terms of phase separation and hole

  4. Ab initio studies on phase transition, thermoelastic, superconducting and thermodynamic properties of the compressed cubic phase of AlH{sub 3}

    SciTech Connect

    Wei, Yong-Kai; Ge, Ni-Na; Chen, Xiang-Rong E-mail: cyfjkf@caep.ac.cn; Ji, Guang-Fu E-mail: cyfjkf@caep.ac.cn; Cai, Ling-Cang; Gu, Zhuo-Wei

    2014-03-28

    The phase transition, thermoelastic, lattice dynamic, and thermodynamic properties of the cubic metallic phase AlH{sub 3} were obtained within the density-function perturbation theory. The calculated elastic modulus and phonon dispersion curves under various pressures at 0 K indicate the cubic phase is both mechanically and dynamically stable above 73 GPa. The superconducting transition temperature T{sub c} was calculated using the Allen-Dynes modification of the McMillan formula based on BCS theory. The calculations show that T{sub c} for the cubic phase AlH{sub 3} is 8.5 K (μ{sup *}=0.1) at the onset of this phase (73 GPa), while decreases to 5.7 K at 80 GPa and almost disappears at 110 GPa, consisting with experimental phenomenon that there was no superconducting transition observed down to 4 K over a wide pressure range 110–164 GPa. It is found that the soft phonon mode for branch 1, namely, the lowest acoustic mode, plays a crucial role in elevating the total EPC parameter λ of cubic AlH{sub 3}. And the evolution of T{sub c} with pressure follows the corresponding change of this soft mode, i.e. this mode is responsible for the disappearance of T{sub c} in experiments. Meanwhile, the softening of this lowest acoustic mode originates from the electronic momentum transfer from M to R point. This phenomenon provides an important insight into why drastic changes in the diffraction pattern were observed in the pressure range of 63–73 GPa in Goncharenko's experiments. Specifically, once finite electronic temperature effects are included, we find that dynamical instabilities can be removed in the phonon dispersion for P≥63 GPa, rendering the metastability of this phase in the range of 63–73 GPa, and T{sub c} (15.4 K) becomes remarkably high under the lowest possible pressure (63 GPa) compared with that of under 73 GPa (8.5 K). Our calculations open the possibility that finite temperature may allow cubic AlH{sub 3} to be

  5. Microgravity Passive Phase Separator

    NASA Technical Reports Server (NTRS)

    Paragano, Matthew; Indoe, William; Darmetko, Jeffrey

    2012-01-01

    A new invention disclosure discusses a structure and process for separating gas from liquids in microgravity. The Microgravity Passive Phase Separator consists of two concentric, pleated, woven stainless- steel screens (25-micrometer nominal pore) with an axial inlet, and an annular outlet between both screens (see figure). Water enters at one end of the center screen at high velocity, eventually passing through the inner screen and out through the annular exit. As gas is introduced into the flow stream, the drag force exerted on the bubble pushes it downstream until flow stagnation or until it reaches an equilibrium point between the surface tension holding bubble to the screen and the drag force. Gas bubbles of a given size will form a front that is moved further down the length of the inner screen with increasing velocity. As more bubbles are added, the front location will remain fixed, but additional bubbles will move to the end of the unit, eventually coming to rest in the large cavity between the unit housing and the outer screen (storage area). Owing to the small size of the pores and the hydrophilic nature of the screen material, gas does not pass through the screen and is retained within the unit for emptying during ground processing. If debris is picked up on the screen, the area closest to the inlet will become clogged, so high-velocity flow will persist farther down the length of the center screen, pushing the bubble front further from the inlet of the inner screen. It is desired to keep the velocity high enough so that, for any bubble size, an area of clean screen exists between the bubbles and the debris. The primary benefits of this innovation are the lack of any need for additional power, strip gas, or location for venting the separated gas. As the unit contains no membrane, the transport fluid will not be lost due to evaporation in the process of gas separation. Separation is performed with relatively low pressure drop based on the large surface

  6. USArray Regional Phase Analysis

    NASA Astrophysics Data System (ADS)

    Buehler, J. S.; Shearer, P. M.

    2014-12-01

    The regional Pn and Sn phases, which are typically described as headwaves that propagate in the uppermost mantle, are sensitive to heterogeneities in the mantle lid and complement other seismic studies with poorer vertical resolution at this depth. We have experimented with a variety of approaches to image the velocity structure and anisotropy in the western U.S., starting with separate Pn and Sn time-term tomographies, but also localized cross-correlation and stacking approaches that benefit from the regular USArray station arrangement. Later we combined the data sets for joint Pn-Sn inversions and the resulting Vp/Vs maps provide further insight into the nature of the seismic anomalies. Now that USArray has reached the east coast, we are updating our models to include the cumulative station footprint. The sparser source distribution in the eastern U.S., and the resulting longer ray paths, provide new challenges and justify the inclusion of additional parameters that account for the velocity gradient in the mantle lid. Our results show generally higher Pn velocities in the eastern U.S., but we observe patches of lower velocities around the New Madrid seismic zone and below the eastern Appalachians. We find that the Pn fast axes generally do not agree with SKS splitting orientations, suggesting significant vertical changes in anisotropy in the upper mantle. For example, the circular pattern of the fast polarization direction of SKS in the western U.S. is much less pronounced in the Pn results, and in the eastern U.S. the dominant Pn fast direction is approximately north-south, whereas the SKS fast polarizations are oriented roughly parallel to the absolute plate motion direction. Since Pn and Sn travel through the crust, they can provide additional information on crustal thickness. In several regions our results and estimates from receiver function studies are inconsistent. For example, beneath the Colorado Plateau our crustal thickness estimates are about 35-40 km

  7. Three phase downhole separator process

    DOEpatents

    Cognata, Louis John

    2008-06-24

    Three Phase Downhole Separator Process (TPDSP) is a process which results in the separation of all three phases, (1) oil, (2) gas, and (3) water, at the downhole location in the well bore, water disposal injection downhole, and oil and gas production uphole.

  8. 78 FR 33911 - Phased Retirement

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-05

    ...The Office of Personnel Management (OPM) is proposing to implement phased retirement, a new human resources tool that allows full-time employees to work a part-time schedule while beginning to draw retirement benefits. Section 100121 of the ``Moving Ahead for Progress in the 21st Century Act,'' or ``MAP-21,'' authorizes phased retirement under the Civil Service Retirement System and the......

  9. Four-quadrant phase detector

    NASA Technical Reports Server (NTRS)

    Manus, E. A.; Wiley, H. P.

    1977-01-01

    Phase detection circuit functions over full 360 degrees covering all four quadrants, and gives linear output that is proportional to phase difference. In addition, its output has single polarity; thus it is compatible with logic circuitry without need for additional processing.

  10. Phase Transitions for Suspension Flows

    NASA Astrophysics Data System (ADS)

    Iommi, Godofredo; Jordan, Thomas

    2013-06-01

    This paper is devoted to studying the thermodynamic formalism for suspension flows defined over countable alphabets. We are mostly interested in the regularity properties of the pressure function. We establish conditions for the pressure function to be real analytic or to exhibit a phase transition. We also construct an example of a potential for which the pressure has countably many phase transitions.

  11. Phase unwrapping via graph cuts.

    PubMed

    Bioucas-Dias, José M; Valadão, Gonçalo

    2007-03-01

    Phase unwrapping is the inference of absolute phase from modulo-2pi phase. This paper introduces a new energy minimization framework for phase unwrapping. The considered objective functions are first-order Markov random fields. We provide an exact energy minimization algorithm, whenever the corresponding clique potentials are convex, namely for the phase unwrapping classical Lp norm, with p > or = 1. Its complexity is KT (n, 3n), where K is the length of the absolute phase domain measured in 2pi units and T (n, m) is the complexity of a max-flow computation in a graph with n nodes and m edges. For nonconvex clique potentials, often used owing to their discontinuity preserving ability, we face an NP-hard problem for which we devise an approximate solution. Both algorithms solve integer optimization problems by computing a sequence of binary optimizations, each one solved by graph cut techniques. Accordingly, we name the two algorithms PUMA, for phase unwrappping max-flow/min-cut. A set of experimental results illustrates the effectiveness of the proposed approach and its competitiveness in comparison with state-of-the-art phase unwrapping algorithms. PMID:17357730

  12. Phased Retirement: The European Experience.

    ERIC Educational Resources Information Center

    Swank, Constance

    This report provides United States corporate and union policymakers with practical information on one alternative work pattern for older employees--phased retirement--from European colleagues who already have implemented or negotiated specific phasing programs. An introduction provides details on the collection of information from companies in…

  13. Phase width reduction project summary

    SciTech Connect

    Clark, D.J.; Xie, Z.Q.; McMahan, M. A.

    1999-11-01

    The purpose of the phase width reduction project, 1993--96, was to reduce the phase width of the 88-Inch Cyclotron beam on target from 5--10 ns to 1--2 ns for certain experiments, such as Gammasphere, which use time-of-flight identification. Since reducing the phase width also reduces beam intensity, tuning should be done to also optimize the transmission. The Multi-turn Collimator slits in the cyclotron center region were used to collimate the early turns radially, thus reducing the phase width from about 5 ns to 1--2 ns FWHM for a Gammasphere beam. The effect of the slits on phase width was verified with a Fast Faraday Cup and with particle and gamma-ray detectors in the external beamline.

  14. Phase-sensitive flow cytometer

    SciTech Connect

    Steinkamp, J.A.

    1992-12-31

    This report describes phase-sensitive flow cytometer (FCM) which provides additional FCM capability to use the fluorescence lifetime of one or more fluorochromes bound to single cells to provide additional information regarding the cells. The resulting fluorescence emission can be resolved into individual fluorescence signals if two fluorochromes are present or can be converted directly to a decay lifetime from a single fluorochrome. The excitation light for the fluorochromes is modulated to produce an amplitude modulated fluorescence pulse as the fluorochrome is excited in the FCM. The modulation signal also forms a reference signal that is phase-shifted a selected amount for subsequent mixing with the output modulated fluorescence intensity signal in phase-sensitive detection circuitry. The output from the phase-sensitive circuitry is then an individual resolved fluorochrome signal or a single fluorochrome decay lifetime, depending on the applied phase shifts.

  15. Phase comparator apparatus and method

    DOEpatents

    Coffield, Frederick E.

    1987-01-01

    The phase change to be measured is multiply measured at artificially incred and decreased values and then averaged to result in greater accuracy. Delayed versions of the reference and input signals are compared in dual channels to the undelayed input signal and the undelayed reference signal, respectively. Resulting time-lengthened and time-shortened phase measurement signals from the dual comparator channels are algebraically combined to provide an analog output signal having an average magnitude accurately proportional to the true phase difference between the undelayed reference and the undelayed input signals. Increased linearity/reproducibility results where relatively high frequency signals (e.g., up to 70 MHz or more) are to be phase compared. An optional voltage clamp on the comparator channel outputs further improves linearity/reproducibility where very small phase differences are being measured.

  16. Two-phase nickel aluminides

    NASA Technical Reports Server (NTRS)

    Khadkikar, P. S.; Vedula, K.; Shabel, B. S.

    1987-01-01

    The as-extruded microstructures of two alloys in the two phase field consisting of Ni3Al and NiAl in the Ni-Al phase diagram exhibit fibrous morphology and consist of Ll(2) Ni3Al and B2 NiAl. These as-extruded microstructures can be modified dramatically by suitable heat treatments. Martensite plus NiAl or martensite plus Ni3Al microstructures are obtained upon quenching from 1523 K. Aging of martensite at 873 K results in the recently identified phase Ni5Al, whereas aging at 1123 K reverts the microstructures to Ni3Al plus NiAl. The microstructures with predominantly martensite of Ni5Al3 phases are brittle in tension at room temperature. The latter microstructure does not deform plastically even in compression at room temperature. However, some promise of room temperature tensile ductility is indicated by the Ni3Al plus NiAl phase mixtures.

  17. Phase stable RF transport system

    DOEpatents

    Curtin, Michael T.; Natter, Eckard F.; Denney, Peter M.

    1992-01-01

    An RF transport system delivers a phase-stable RF signal to a load, such as an RF cavity of a charged particle accelerator. A circuit generates a calibration signal at an odd multiple frequency of the RF signal where the calibration signal is superimposed with the RF signal on a common cable that connects the RF signal with the load. Signal isolating diplexers are located at both the RF signal source end and load end of the common cable to enable the calibration to be inserted and extracted from the cable signals without any affect on the RF signal. Any phase shift in the calibration signal during traverse of the common cable is then functionally related to the phase shift in the RF signal. The calibration phase shift is used to control a phase shifter for the RF signal to maintain a stable RF signal at the load.

  18. Phase-sensitive flow cytometer

    DOEpatents

    Steinkamp, John A.

    1993-01-01

    A phase-sensitive flow cytometer (FCM) provides additional FCM capability to use the fluorescence lifetime of one or more fluorochromes bound to single cells to provide additional information regarding the cells. The resulting fluorescence emission can be resolved into individual fluorescence signals if two fluorochromes are present or can be converted directly to a decay lifetime from a single fluorochrome. The excitation light for the fluorochromes is modulated to produce an amplitude modulated fluorescence pulse as the fluorochrome is excited in the FCM. The modulation signal also forms a reference signal that is phase-shifted a selected amount for subsequent mixing with the output modulated fluorescence intensity signal in phase-sensitive detection circuitry. The output from the phase-sensitive circuitry is then an individual resolved fluorochrome signal or a single fluorochrome decay lifetime, depending on the applied phase shifts.

  19. Phase-sensitive flow cytometer

    DOEpatents

    Steinkamp, J.A.

    1993-12-14

    A phase-sensitive flow cytometer (FCM) provides additional FCM capability to use the fluorescence lifetime of one or more fluorochromes bound to single cells to provide additional information regarding the cells. The resulting fluorescence emission can be resolved into individual fluorescence signals if two fluorochromes are present or can be converted directly to a decay lifetime from a single fluorochrome. The excitation light for the fluorochromes is modulated to produce an amplitude modulated fluorescence pulse as the fluorochrome is excited in the FCM. The modulation signal also forms a reference signal that is phase-shifted a selected amount for subsequent mixing with the output modulated fluorescence intensity signal in phase-sensitive detection circuitry. The output from the phase-sensitive circuitry is then an individual resolved fluorochrome signal or a single fluorochrome decay lifetime, depending on the applied phase shifts. 15 figures.

  20. Phase Contrast Imaging in Neonates

    PubMed Central

    Zhong, Kai; Ernst, Thomas; Buchthal, Steve; Speck, Oliver; Anderson, Lynn; Chang, Linda

    2011-01-01

    Magnetic resonance phase images can yield superior gray and white matter contrast compared to conventional magnitude images. However, the underlying contrast mechanisms are not yet fully understood. Previous studies have been limited to high field acquisitions in adult volunteers and patients. In this study, phase imaging in the neonatal brain is demonstrated for the first time. Compared to adults, phase differences between gray and white matter are significantly reduced but not inverted in neonates with little myelination and iron deposits in their brains. The remaining phase difference between the neonatal and adult brains may be due to different macromolecule concentration in the unmyelinated brain of the neonates and thus different frequency due to water macromolecule exchange. Additionally, the susceptibility contrast from brain myelination can be separately studied in neonates during brain development. Therefore, magnetic resonance phase imaging is suggested as a novel tool to study neonatal brain development and pathologies in neonates. PMID:21232619

  1. Planar infrared binary phase reflectarray.

    PubMed

    Ginn, James; Lail, Brian; Alda, Javier; Boreman, Glenn

    2008-04-15

    A reflective, binary phase reflectarray is demonstrated in the infrared, at a wavelength of 10.6 microm. The unique aspect of this work, at this frequency band, is that the specific desired phase shift is achieved using an array of subwavelength metallic patches on top of a ground-plane-backed dielectric stand-off layer. This is an alternative to the usual method of constructing a reflective Fresnel zone plate by means of a given thickness of dielectric. This initial demonstration of the reflectarray approach at infrared is significant in that there is inherent flexibility to create a range of phase shifts by varying the dimensions of the patches. This will allow for a multilevel phase distribution, or even a continuous variation of phase, across an optical surface with only two-dimensional lithography, avoiding the need for dielectric height variations. PMID:18414530

  2. Differentiation method for phase recovery

    NASA Astrophysics Data System (ADS)

    Özcan, Meriç

    2015-03-01

    Here we consider a derivative based method for phase recovery and demonstrate a numerical method that can be described as differentiate and cross multiply operation to obtain the phase gradient. This method uses quadrature phase data that is in sine and cosine form, which is a natural outcome many interferometric measurements including that of digital holographic reconstruction. Since the differentiation is performed on trigonometric functions which are discrete, it is shown that the method of differentiation and the sampling rate are important considerations especially for the noise corrupt signals. The method is initially developed for 1D phase signals, and then later extended to 2D. Noise performance of the method is also investigated, and it is shown that for extremely noisy signals the method can be adapted to an iteration routine which recovers the phase successfully. We present simulations and the experimental results which show the validity of the approach.

  3. Vapor Phase Catalytic Ammonia Reduction

    NASA Technical Reports Server (NTRS)

    Flynn, Michael T.; Harper, Lynn D. (Technical Monitor)

    1994-01-01

    This paper discusses the development of a Vapor Phase Catalytic Ammonia Reduction (VPCAR) teststand and the results of an experimental program designed to evaluate the potential of the technology as a water purification process. In the experimental program the technology is evaluated based upon product water purity, water recovery rate, and power consumption. The experimental work demonstrates that the technology produces high purity product water and attains high water recovery rates at a relatively high specific power consumption. The experimental program was conducted in 3 phases. In phase I an Igepon(TM) soap and water mixture was used to evaluate the performance of an innovative Wiped-Film Rotating-Disk evaporator and associated demister. In phase II a phenol-water solution was used to evaluate the performance of the high temperature catalytic oxidation reactor. In phase III a urine analog was used to evaluate the performance of the combined distillation/oxidation functions of the processor.

  4. {sup 129}I Interlaboratory comparison: phase I and phase II

    SciTech Connect

    Caffee, M W; Roberts, M L

    1999-09-30

    An interlaboratory comparison exercise for {sup 129}I was organized and conducted. Nine laboratories participated in the exercise to either a full or limited extent. In Phase I of the comparison, 11 samples were measured. The suite of samples contained both synthetic ''standard type'' materials (i.e., AgI) and environmental materials. The isotopic {sup 129}I/{sup 127}I ratios of the samples varied from 10{sup {minus}8} to 10{sup {minus}14}. In this phase, each laboratory was responsible for its own chemical preparation of the samples. In Phase I, the {sup 129}I AMS measurements for prepared AgI were in good agreement. However, large discrepancies were seen in {sup 129}I AMS measurements of environmental samples. Because of the large discrepancies seen in the Phase I {sup 129}I intercomparison, a subsequent study was conducted. In Phase II of the {sup 129}I intercomparison, three separate laboratories prepared AgI from two environmental samples (IAEA 375 soil and maples leaves). Each laboratory used its own chemical preparation method with each of the methods being distinctly different. The resulting six samples (two sets of three) were then re-distributed to the participating {sup 129}I AMS facilities and {sup 129}I/{sup 127}I ratios measured. Results and discussion of both the Phase I and Phase II interlaboratory comparison are presented.

  5. Quantitative phase imaging using grating-based quadrature phase interferometer

    NASA Astrophysics Data System (ADS)

    Wu, Jigang; Yaqoob, Zahid; Heng, Xin; Cui, Xiquan; Yang, Changhuei

    2007-02-01

    In this paper, we report the use of holographic gratings, which act as the free-space equivalent of the 3x3 fiber-optic coupler, to perform full field phase imaging. By recording two harmonically-related gratings in the same holographic plate, we are able to obtain nontrivial phase shift between different output ports of the gratings-based Mach-Zehnder interferometer. The phase difference can be adjusted by changing the relative phase of the recording beams when recording the hologram. We have built a Mach-Zehnder interferometer using harmonically-related holographic gratings with 600 and 1200 lines/mm spacing. Two CCD cameras at the output ports of the gratings-based Mach-Zehnder interferometer are used to record the full-field quadrature interferograms, which are subsequently processed to reconstruct the phase image. The imaging system has ~12X magnification with ~420μmx315μm field-of-view. To demonstrate the capability of our system, we have successfully performed phase imaging of a pure phase object and a paramecium caudatum.

  6. Octahedral tilting, monoclinic phase and the phase diagram of PZT

    NASA Astrophysics Data System (ADS)

    Cordero, F.; Trequattrini, F.; Craciun, F.; Galassi, C.

    2011-10-01

    Anelastic and dielectric spectroscopy measurements on PbZr1-xTixO3 (PZT) close to the morphotropic (MPB) and antiferroelectric boundaries provide new insight into some controversial aspects of its phase diagram. No evidence is found of a border separating monoclinic (M) from rhombohedral (R) phases, in agreement with recent structural studies supporting a coexistence of the two phases over a broad composition range x < 0.5, with the fraction of M increasing toward the MPB. It is also discussed why the observed maximum of elastic compliance appears to be due to a rotational instability of the polarization linearly coupled to shear strain. Therefore it cannot be explained by extrinsic softening from finely twinned R phase alone, but indicates the presence also of M phase, not necessarily homogeneous. A new diffuse transition is found within the ferroelectric phase near x ˜ 0.1, at a temperature TIT higher than the well established boundary TT to the phase with tilted octahedra. It is proposed that around TIT the octahedra start rotating in a disordered manner and finally become ordered below TT. In this interpretation, the onset temperature for octahedral tilting monotonically increases up to the antiferroelectric transition of PbZrO3, and the depression of TT(x) below x = 0.18 would be a consequence of the partial relief of the mismatch between the average cation radii with the initial stage of tilting below TIT.

  7. Inhomogeneous phase shifting: an algorithm for nonconstant phase displacements

    SciTech Connect

    Tellez-Quinones, Alejandro; Malacara-Doblado, Daniel

    2010-11-10

    In this work, we have developed a different algorithm than the classical one on phase-shifting interferometry. These algorithms typically use constant or homogeneous phase displacements and they can be quite accurate and insensitive to detuning, taking appropriate weight factors in the formula to recover the wrapped phase. However, these algorithms have not been considered with variable or inhomogeneous displacements. We have generalized these formulas and obtained some expressions for an implementation with variable displacements and ways to get partially insensitive algorithms with respect to these arbitrary error shifts.

  8. Double random phase encoding using phase reservation and compression

    NASA Astrophysics Data System (ADS)

    Chen, Wen; Chen, Xudong

    2014-02-01

    In recent years, various studies have been conducted to illustrate the vulnerability of double random phase encoding (DRPE). In this paper, we propose a novel method via phase reservation and compression to enhance DRPE security. Only a compressed phase distribution is available in the CCD plane, and the amplitude component is not available or requested for optical decryption. Since only noise-like distributions can be obtained by using the correct security keys during optical decryption, a nonlinear correlation algorithm is further applied for authenticating the decrypted image. It is demonstrated that valid conditions for attack algorithms are broken and high security can be achieved for the DRPE system.

  9. Numerical Studies of Topological phases

    NASA Astrophysics Data System (ADS)

    Geraedts, Scott

    The topological phases of matter have been a major part of condensed matter physics research since the discovery of the quantum Hall effect in the 1980s. Recently, much of this research has focused on the study of systems of free fermions, such as the integer quantum Hall effect, quantum spin Hall effect, and topological insulator. Though these free fermion systems can play host to a variety of interesting phenomena, the physics of interacting topological phases is even richer. Unfortunately, there is a shortage of theoretical tools that can be used to approach interacting problems. In this thesis I will discuss progress in using two different numerical techniques to study topological phases. Recently much research in topological phases has focused on phases made up of bosons. Unlike fermions, free bosons form a condensate and so interactions are vital if the bosons are to realize a topological phase. Since these phases are difficult to study, much of our understanding comes from exactly solvable models, such as Kitaev's toric code, as well as Levin-Wen and Walker-Wang models. We may want to study systems for which such exactly solvable models are not available. In this thesis I present a series of models which are not solvable exactly, but which can be studied in sign-free Monte Carlo simulations. The models work by binding charges to point topological defects. They can be used to realize bosonic interacting versions of the quantum Hall effect in 2D and topological insulator in 3D. Effective field theories of ''integer'' (non-fractionalized) versions of these phases were available in the literature, but our models also allow for the construction of fractional phases. We can measure a number of properties of the bulk and surface of these phases. Few interacting topological phases have been realized experimentally, but there is one very important exception: the fractional quantum Hall effect (FQHE). Though the fractional quantum Hall effect we discovered over 30

  10. Supercooling and phase coexistence in cosmological phase transitions

    SciTech Connect

    Megevand, Ariel; Sanchez, Alejandro D.

    2008-03-15

    Cosmological phase transitions are predicted by particle physics models, and have a variety of important cosmological consequences, which depend strongly on the dynamics of the transition. In this work we investigate in detail the general features of the development of a first-order phase transition. We find thermodynamical constraints on some quantities that determine the dynamics, namely, the latent heat, the radiation energy density, and the false-vacuum energy density. Using a simple model with a Higgs field, we study numerically the amount and duration of supercooling and the subsequent reheating and phase coexistence. We analyze the dependence of the dynamics on the different parameters of the model, namely, the energy scale, the number of degrees of freedom, and the couplings of the scalar field with bosons and fermions. We also inspect the implications for the cosmological outcomes of the phase transition.

  11. Phase shift estimation in interferograms with unknown phase step

    NASA Astrophysics Data System (ADS)

    Dalmau, Oscar; Rivera, Mariano; Gonzalez, Adonai

    2016-08-01

    We first present two closed formulas for computing the phase shift in interferograms with unknown phase step. These formulas obtain theoretically the exact phase step in fringe pattern without noise and only require the information in two pixels of the image. The previous formulas allows us to define a functional that yields an estimate of the phase step in interferograms corrupted by noise. In the experiment we use the standard Least Square formulation which also yields a closed formula, although the general formulation admits a robust potential. We provide two possible implementations of our approach, one in which the sites can be randomly selected and the other in which we can scan the whole image. The experiments show that the proposed algorithm presents the best results compared with state of the art algorithms.

  12. Phase unwrapping using discontinuity optimization

    SciTech Connect

    Flynn, T.J.

    1998-03-01

    In SAR interferometry, the periodicity of the phase must be removed using two-dimensional phase unwrapping. The goal of the procedure is to find a smooth surface in which large spatial phase differences, called discontinuities, are restricted to places where their presence is reasonable. The pioneering work of Goldstein et al. identified points of local unwrap inconsistency called residues, which must be connected by discontinuities. This paper presents an overview of recent work that treats phase unwrapping as a discrete optimization problem with the constraint that residues must be connected. Several algorithms use heuristic methods to reduce the total number of discontinuities. Constantini has introduced the weighted sum of discontinuity magnitudes as a criterion of unwrap error and shown how algorithms from optimization theory are used to minimize it. Pixels of low quality are given low weight to guide discontinuities away from smooth, high-quality regions. This method is generally robust, but if noise is severe it underestimates the steepness of slopes and the heights of peaks. This problem is mitigated by subtracting (modulo 2{pi}) a smooth estimate of the unwrapped phase from the data, then unwrapping the resulting residual phase. The unwrapped residual is added to the smooth estimate to produce the final unwrapped phase. The estimate can be computed by lowpass filtering of an existing unwrapped phase; this makes possible an iterative algorithm in which the result of each iteration provides the estimate for the next. An example illustrates the results of optimal discontinuity placement and the improvement from unwrapping of the residual phase.

  13. Phase transitions in disordered systems

    NASA Astrophysics Data System (ADS)

    Hrahsheh, Fawaz Y.

    Disorder can have a wide variety of consequences for the physics of phase transitions. Some transitions remain unchanged in the presence of disorder while others are completely destroyed. In this thesis we study the effects of disorder on several classical and quantum phase transitions in condensed matter systems. After a brief introduction, we study the ferromagnetic phase transition in a randomly layered Heisenberg magnet using large-scale Monte-Carlo simulations. Our results provide numerical evidence for the exotic infinite-randomness scenario. We study classical and quantum smeared phase transitions in substitutional alloys A1-xBx. Our results show that the disorder completely destroys the phase transition with a pronounced tail of the ordered phase developing for all compositions x < 1. In addition, we find that short-ranged disorder correlations can have a dramatic effect on the transition. Moreover, we show an experimental realization of the composition-tuned ferromagnetic-to-paramagnetic quantum phase transition in Sr1-xCa xRuO3. We investigate the effects of disorder on first-order quantum phase transitions on the example of the N-color quantum Ashkin-Teller model. By means of a strong disorder renormalization group, we demonstrate that disorder rounds the first-order transition to a continuous one for both weak and strong coupling between the colors. Finally, we investigate the superfluid-insulator quantum phase transition of one-dimensional bosons with off-diagonal disorder by means of large-scale Monte-Carlo simulations. Beyond a critical disorder strength, we find nonuniversal, disorder dependent critical behavior.

  14. Liquid-phase compositions from vapor-phase analyses

    SciTech Connect

    Davis, W. Jr. ); Cochran, H.D. )

    1990-02-01

    Arsenic normally is not considered to be a contaminant. However, because arsenic was found in many cylinders of UF{sub 6}, including in corrosion products, a study was performed of the distribution of the two arsenic fluorides, AsF{sub 3} and AsF{sub 5}, between liquid and vapor phases. The results of the study pertain to condensation or vaporization of liquid UF{sub 6}. This study includes use of various experimental data plus many extrapolations necessitated by the meagerness of the experimental data. The results of this study provide additional support for the vapor-liquid equilibrium model of J.M. Prausnitz and his coworkers as a means of describing the distribution of various impurities between vapor and liquid phases of UF{sub 6}. Thus, it is concluded that AsF{sub 3} will tend to concentrate in the liquid phase but that the concentration of AsF{sub 5} in the vapor phase will exceed its liquid-phase concentration by a factor of about 7.5, which is in agreement with experimental data. Because the weight of the liquid phase in a condensation operation may be in the range of thousands of times that of the vapor phase, most of any AsF{sub 5} will be in the liquid phase in spite of this separation factor of 7.5. It may also be concluded that any arsenic fluorides fed into a uranium isotope separation plant will either travel with other low-molecular-weight gases or react with materials present in the plant. 25 refs., 3 figs., 6 tabs.

  15. Laparoscopic Radiofrequency Fibroid Ablation: Phase II and Phase III Results

    PubMed Central

    Pemueller, Rodolfo Robles; Garza Leal, José Gerardo; Abbott, Karen R.; Falls, Janice L.; Macer, James

    2014-01-01

    Background and Objectives: To review phase II and phase III treatments of symptomatic uterine fibroids (myomas) using laparoscopic radiofrequency volumetric thermal ablation (RFVTA). Methods: We performed a retrospective, multicenter clinical analysis of 206 consecutive cases of ultrasound-guided laparoscopic RFVTA of symptomatic myomas conducted on an outpatient basis under two phase II studies at 2 sites (n = 69) and one phase III study at 11 sites (n = 137). Descriptive and exploratory, general trend, and matched-pair analyses were applied. Results: From baseline to 12 months in the phase II study, the mean transformed symptom severity scores improved from 53.9 to 8.8 (P < .001) (n = 57), health-related quality-of-life scores improved from 48.5 to 92.0 (P < .001) (n = 57), and mean uterine volume decreased from 204.4 cm3 to 151.4 cm3 (P = .008) (n = 58). Patients missed a median of 4 days of work (range, 2–10 days). The rate of possible device-related adverse events was 1.4% (1 of 69). In the phase III study, approximately 98% of patients were assessed at 12 months, and their transformed symptom severity scores, health-related quality-of-life scores, mean decrease in uterine volume, and mean menstrual bleeding reduction were also significant. Patients in phase III missed a median of 5 days of work (range, 1–29 days). The rate of periprocedural device-related adverse events was 3.5% (5 of 137). Despite the enrollment requirement for patients in both phases to have completed childbearing, 4 pregnancies occurred within the first year after treatment. Conclusions: RFVTA does not require any uterine incisions and provides a uterine-sparing procedure with rapid recovery, significant reduction in uterine size, significant reduction or elimination of myoma symptoms, and significant improvement in quality of life. PMID:24960480

  16. Two-phase/two-phase heat exchanger analysis

    NASA Technical Reports Server (NTRS)

    Kim, Rhyn H.

    1992-01-01

    A capillary pumped loop (CPL) system with a condenser linked to a double two-phase heat exchanger is analyzed numerically to simulate the performance of the system from different starting conditions to a steady state condition based on a simplified model. Results of the investigation are compared with those of similar apparatus available in the Space Station applications of the CPL system with a double two-phase heat exchanger.

  17. Dynamic phase-shifting photoelasticity.

    PubMed

    Asundi, A; Tong, L; Boay, C G

    2001-08-01

    The application of phase-shifting photoelasticity to a real-time dynamic event involves simultaneous recording of the four phase-shifted images. Here an instrument, believed to be novel, is developed and described for this purpose. Use of a Multispec Imager is introduced into digital photoelasticity for the first time to our knowledge. This device enables splitting the optical energy of an object into four identical paths, thus permitting recording of the required four phase-shifted images. Experimental demonstration is provided for validation. PMID:18360395

  18. Berry's phase in rotating systems

    NASA Astrophysics Data System (ADS)

    Cui, Shi-Min; Xu, Hong-Hua

    1991-09-01

    It is shown that, in addition to the Aharonov-Bohm-like phase studied previously [M. V. Berry, Proc. R. Soc. London Ser. A 392, 45 (1984); Y. Aharakov and J. Anandan, Phys. Rev. Lett. 58, 1593 (1987); C. H. Tsai and D. Neilson, Phys. Rev. A 37, 619 (1988)], Berry's topological phase also appears for purely mechanical reasons in systems rotating at slowly-time-varying angular velocity about a fixed center. A possible experiment to probe this manifestation of Berry's phase is discussed.

  19. SNMR pulse sequence phase cycling

    DOEpatents

    Walsh, David O; Grunewald, Elliot D

    2013-11-12

    Technologies applicable to SNMR pulse sequence phase cycling are disclosed, including SNMR acquisition apparatus and methods, SNMR processing apparatus and methods, and combinations thereof. SNMR acquisition may include transmitting two or more SNMR pulse sequences and applying a phase shift to a pulse in at least one of the pulse sequences, according to any of a variety cycling techniques. SNMR processing may include combining SNMR from a plurality of pulse sequences comprising pulses of different phases, so that desired signals are preserved and indesired signals are canceled.

  20. Machine learning phases of matter

    NASA Astrophysics Data System (ADS)

    Carrasquilla, Juan; Stoudenmire, Miles; Melko, Roger

    We show how the technology that allows automatic teller machines read hand-written digits in cheques can be used to encode and recognize phases of matter and phase transitions in many-body systems. In particular, we analyze the (quasi-)order-disorder transitions in the classical Ising and XY models. Furthermore, we successfully use machine learning to study classical Z2 gauge theories that have important technological application in the coming wave of quantum information technologies and whose phase transitions have no conventional order parameter.

  1. Phase-locked laser array

    NASA Technical Reports Server (NTRS)

    Botez, Dan (Inventor)

    1987-01-01

    A phase-locked laser array comprises a body of semiconductor material having means for defining a plurality of substantially parallel lasing zones which are spaced an effective distance apart so that the modes of the adjacent lasing zones are phase-locked to one another. One of the array electrodes comprises a plurality of electrical contacts to the body between the lasing zones. These contacts provide an enhanced current density profile and thus an increase in the gain in the regions between the lasing zones so that zero degree phase-shift operation between adjacent lasing zones is achievable.

  2. Berry phase in nonlinear systems

    SciTech Connect

    Liu, J.; Fu, L. B.

    2010-05-15

    The Berry phase acquired by an eigenstate that experienced a nonlinear adiabatic evolution is investigated thoroughly. The circuit integral of the Berry connection of the instantaneous eigenstate cannot account for the adiabatic geometric phase, while the Bogoliubov excitations around the eigenstates are found to be accumulated during the nonlinear adiabatic evolution and contribute a finite phase of geometric nature. A two-mode model is used to illustrate our theory. Our theory is applicable to Bose-Einstein condensate, nonlinear light propagation, and Ginzburg-Landau equations for complex order parameters in condensed-matter physics.

  3. Phase space quantum mechanics - Direct

    SciTech Connect

    Nasiri, S.; Sobouti, Y.; Taati, F.

    2006-09-15

    Conventional approach to quantum mechanics in phase space (q,p), is to take the operator based quantum mechanics of Schroedinger, or an equivalent, and assign a c-number function in phase space to it. We propose to begin with a higher level of abstraction, in which the independence and the symmetric role of q and p is maintained throughout, and at once arrive at phase space state functions. Upon reduction to the q- or p-space the proposed formalism gives the conventional quantum mechanics, however, with a definite rule for ordering of factors of noncommuting observables. Further conceptual and practical merits of the formalism are demonstrated throughout the text.

  4. Multichannel Phase and Power Detector

    NASA Technical Reports Server (NTRS)

    Li, Samuel; Lux, James; McMaster, Robert; Boas, Amy

    2006-01-01

    An electronic signal-processing system determines the phases of input signals arriving in multiple channels, relative to the phase of a reference signal with which the input signals are known to be coherent in both phase and frequency. The system also gives an estimate of the power levels of the input signals. A prototype of the system has four input channels that handle signals at a frequency of 9.5 MHz, but the basic principles of design and operation are extensible to other signal frequencies and greater numbers of channels. The prototype system consists mostly of three parts: An analog-to-digital-converter (ADC) board, which coherently digitizes the input signals in synchronism with the reference signal and performs some simple processing; A digital signal processor (DSP) in the form of a field-programmable gate array (FPGA) board, which performs most of the phase- and power-measurement computations on the digital samples generated by the ADC board; and A carrier board, which allows a personal computer to retrieve the phase and power data. The DSP contains four independent phase-only tracking loops, each of which tracks the phase of one of the preprocessed input signals relative to that of the reference signal (see figure). The phase values computed by these loops are averaged over intervals, the length of which is chosen to obtain output from the DSP at a desired rate. In addition, a simple sum of squares is computed for each channel as an estimate of the power of the signal in that channel. The relative phases and the power level estimates computed by the DSP could be used for diverse purposes in different settings. For example, if the input signals come from different elements of a phased-array antenna, the phases could be used as indications of the direction of arrival of a received signal and/or as feedback for electronic or mechanical beam steering. The power levels could be used as feedback for automatic gain control in preprocessing of incoming signals

  5. Geometrical Phases in Quantum Mechanics

    NASA Astrophysics Data System (ADS)

    Christian, Joy Julius

    In quantum mechanics, the path-dependent geometrical phase associated with a physical system, over and above the familiar dynamical phase, was initially discovered in the context of adiabatically changing environments. Subsequently, Aharonov and Anandan liberated this phase from the original formulation of Berry, which used Hamiltonians, dependent on curves in a classical parameter space, to represent the cyclic variations of the environments. Their purely quantum mechanical treatment, independent of Hamiltonians, instead used the non-trivial topological structure of the projective space of one-dimensional subspaces of an appropriate Hilbert space. The geometrical phase, in their treatment, results from a parallel transport of the time-dependent pure quantum states along a curve in this space, which is endowed with an abelian connection. Unlike Berry, they were able to achieve this without resort to an adiabatic approximation or to a time-independent eigenvalue equation. Prima facie, these two approaches are conceptually quite different. After a review of both approaches, an exposition bridging this apparent conceptual gap is given; by rigorously analyzing a model composite system, it is shown that, in an appropriate correspondence limit, the Berry phase can be recovered as a special case from the Aharonov-Anandan phase. Moreover, the model composite system is used to show that Berry's correction to the traditional Born-Oppenheimer energy spectra indeed brings the spectra closer to the exact results. Then, an experimental arrangement to measure geometrical phases associated with cyclic and non-cyclic variations of quantum states of an entangled composite system is proposed, utilizing the fundamental ideas of the recently opened field of two-particle interferometry. This arrangement not only resolves the controversy regarding the true nature of the phases associated with photon states, but also unequivocally predicts experimentally accessible geometrical phases in a

  6. 129I interlaboratory comparison: phase I and phase II results

    SciTech Connect

    Roberts, M.I.; Caffee, M.W.; Proctor, I.D.

    1997-07-01

    An interlaboratory comparison exercise for 129I was organized and conducted. A total of nine laboratories participated in the exercise to either a full or limited extent. In Phase I of the comparison, a suite of 11 samples were measured. The suite of samples contained both synthetic `standard type` materials (i.e., AgI) and environmental materials. The isotopic 129I/127I ratios of the samples varied from 10`-8 to 10`-14. In this phase, each laboratory was responsible for its own chemical preparation of the environmental samples. The 129I AMS measurements obtained at different laboratories for prepared AgI were in good agreement. However, large discrepancies were seen in 129I AMS measurements of environmental samples. Because of the large discrepancies seen in the Phase I intercomparison, a subsequent study was conducted. In Phase II of the comparison, AgI was prepared from two environmental samples (IAEA 375 soil and maples leaves) by three separate laboratories. Each laboratory used its own chemical preparation method with each of the methods being distinctly different. The resulting six samples (two sets of three) were then redistributed to the participating 129I AMS facilities and 129I/127I ratios measured. Results and discussion of both the Phase I and Phase II interlaboratory comparison are presented.

  7. Experimental study of phase separation in dividing two phase flow

    SciTech Connect

    Qian Yong; Yang Zhilin; Xu Jijun

    1996-12-31

    Experimental study of phase separation of air-water two phase bubbly, slug flow in the horizontal T-junction is carried out. The influences of the inlet mass quality X1, mass extraction rate G3/G1, and fraction of extracted liquid QL3/QL1 on phase separation characteristics are analyzed. For the first time, the authors have found and defined pulsating run effect by the visual experiments, which show that under certain conditions, the down stream flow of the T-junction has strangely affected the phase redistribution of the junction, and firstly point out that the downstream geometric condition is very important to the study of phase separation phenomenon of two-phase flow in a T-junction. This kind of phenomenon has many applications in the field of energy, power, petroleum and chemical industries, such as the loss of coolant accident (LOCA) caused by a small break in a horizontal coolant pipe in nuclear reactor, and the flip-flop effect in the natural gas transportation pipeline system, etc.

  8. In situ phase transformation of Laves phase from Chi-phase in Mo-containing Fe–Cr–Ni alloys

    DOE PAGESBeta

    Tan, L.; Yang, Y.

    2015-11-01

    For an in situ phase transformation of the Chi (χ) phase to the Laves phase we observed in a Fe–Cr–Ni–Mo model alloy. The morphology, composition, and crystal structure of the χ and Laves phases, and their orientation relationship with the matrix austenite phase were investigated. The resulted Laves phase has larger lattice mismatch with the matrix phase than the χ phase, leading to the increase of local strain fields and the formation of dislocations. Moreover, this finding is helpful to understand the precipitation behavior of the intermetallic phases in the Mo-containing austenitic stainless steels.

  9. Hadron-Quark Phase Transition

    SciTech Connect

    Cavagnoli, Rafael; Menezes, Debora P.; Providencia, Constanca

    2009-06-03

    In the present work we study the hadron-quarkphase transition with boson condensation by investigating the binodal surface and extending it to finite temperature in order to mimic the QCD phase diagram.

  10. Berry phase in Heisenberg representation

    NASA Technical Reports Server (NTRS)

    Andreev, V. A.; Klimov, Andrei B.; Lerner, Peter B.

    1994-01-01

    We define the Berry phase for the Heisenberg operators. This definition is motivated by the calculation of the phase shifts by different techniques. These techniques are: the solution of the Heisenberg equations of motion, the solution of the Schrodinger equation in coherent-state representation, and the direct computation of the evolution operator. Our definition of the Berry phase in the Heisenberg representation is consistent with the underlying supersymmetry of the model in the following sense. The structural blocks of the Hamiltonians of supersymmetrical quantum mechanics ('superpairs') are connected by transformations which conserve the similarity in structure of the energy levels of superpairs. These transformations include transformation of phase of the creation-annihilation operators, which are generated by adiabatic cyclic evolution of the parameters of the system.

  11. Phase Change Material Heat Exchangers

    NASA Video Gallery

    NASA’s Game Changing Development is taking on a technologydevelopment and demonstration effort to design, build, and test the next generation of Phase Change Material Heat Exchangers (PCM HXs) on ...

  12. Phase-Controlled Polarization Modulators

    NASA Technical Reports Server (NTRS)

    Chuss, D. T.; Wollack, E. J.; Novak, G.; Moseley, S. H.; Pisano, G.; Krejny, M.; U-Yen, K.

    2012-01-01

    We report technology development of millimeter/submillimeter polarization modulators that operate by introducing a a variable, controlled phase delay between two orthogonal polarization states. The variable-delay polarization modulator (VPM) operates via the introduction of a variable phase delay between two linear orthogonal polarization states, resulting in a variable mapping of a single linear polarization into a combination of that Stokes parameter and circular (Stokes V) polarization. Characterization of a prototype VPM is presented at 350 and 3000 microns. We also describe a modulator in which a variable phase delay is introduced between right- and left- circular polarization states. In this architecture, linear polarization is fully modulated. Each of these devices consists of a polarization diplexer parallel to and in front of a movable mirror. Modulation involves sub-wavelength translations of the mirror that change the magnitude of the phase delay.

  13. Gas-phase chemical dynamics

    SciTech Connect

    Weston, R.E. Jr.; Sears, T.J.; Preses, J.M.

    1993-12-01

    Research in this program is directed towards the spectroscopy of small free radicals and reactive molecules and the state-to-state dynamics of gas phase collision, energy transfer, and photodissociation phenomena. Work on several systems is summarized here.

  14. NHEXAS PHASE I MARYLAND STUDY

    EPA Science Inventory

    The National Human Exposure Assessment Survey (NHEXAS) is a federal interagency research effort coordinated by the Environmental Protection Agency (EPA), Office of Research and Development (ORD). Phase I consists of demonstration/scoping studies using probability-based sampling ...

  15. Fly Photoreceptors Encode Phase Congruency

    PubMed Central

    Friederich, Uwe; Billings, Stephen A.; Hardie, Roger C.; Juusola, Mikko; Coca, Daniel

    2016-01-01

    More than five decades ago it was postulated that sensory neurons detect and selectively enhance behaviourally relevant features of natural signals. Although we now know that sensory neurons are tuned to efficiently encode natural stimuli, until now it was not clear what statistical features of the stimuli they encode and how. Here we reverse-engineer the neural code of Drosophila photoreceptors and show for the first time that photoreceptors exploit nonlinear dynamics to selectively enhance and encode phase-related features of temporal stimuli, such as local phase congruency, which are invariant to changes in illumination and contrast. We demonstrate that to mitigate for the inherent sensitivity to noise of the local phase congruency measure, the nonlinear coding mechanisms of the fly photoreceptors are tuned to suppress random phase signals, which explains why photoreceptor responses to naturalistic stimuli are significantly different from their responses to white noise stimuli. PMID:27336733

  16. Phase nucleation in curved space

    NASA Astrophysics Data System (ADS)

    Gómez, Leopoldo; García, Nicolás; Vitelli, Vincenzo; Lorenzana, José; Daniel, Vega

    Nucleation and growth is the dominant relaxation mechanism driving first-order phase transitions. In two-dimensional flat systems, nucleation has been applied to a wide range of problems in physics, chemistry and biology. Here we study nucleation and growth of two-dimensional phases lying on curved surfaces and show that curvature modifies both critical sizes of nuclei and paths towards the equilibrium phase. In curved space, nucleation and growth becomes inherently inhomogeneous and critical nuclei form faster on regions of positive Gaussian curvature. Substrates of varying shape display complex energy landscapes with several geometry-induced local minima, where initially propagating nuclei become stabilized and trapped by the underlying curvature (Gómez, L. R. et al. Phase nucleation in curved space. Nat. Commun. 6:6856 doi: 10.1038/ncomms7856 (2015).).

  17. Fly Photoreceptors Encode Phase Congruency.

    PubMed

    Friederich, Uwe; Billings, Stephen A; Hardie, Roger C; Juusola, Mikko; Coca, Daniel

    2016-01-01

    More than five decades ago it was postulated that sensory neurons detect and selectively enhance behaviourally relevant features of natural signals. Although we now know that sensory neurons are tuned to efficiently encode natural stimuli, until now it was not clear what statistical features of the stimuli they encode and how. Here we reverse-engineer the neural code of Drosophila photoreceptors and show for the first time that photoreceptors exploit nonlinear dynamics to selectively enhance and encode phase-related features of temporal stimuli, such as local phase congruency, which are invariant to changes in illumination and contrast. We demonstrate that to mitigate for the inherent sensitivity to noise of the local phase congruency measure, the nonlinear coding mechanisms of the fly photoreceptors are tuned to suppress random phase signals, which explains why photoreceptor responses to naturalistic stimuli are significantly different from their responses to white noise stimuli. PMID:27336733

  18. NHEXAS PHASE I ARIZONA STUDY

    EPA Science Inventory

    The National Human Exposure Assessment Survey (NHEXAS) is a federal interagency research effort coordinated by the Environmental Protection Agency (EPA), Office of Research and Development (ORD). The objective of the NHEXAS Phase I Arizona study was to determine the distribution...

  19. Trends in phased array development

    NASA Astrophysics Data System (ADS)

    Schell, A. C.

    1986-03-01

    In the past 15 years, several outstanding phased arrays have been taken into service for functions involving defense applications. It is pointed out, however, that the impact of phased array technology on radar and communications antennas has been minor in comparison to the impact of solid-state technology on the other major subsystem, the signal processor. This situation is mainly related to cost considerations, and the scale of the commercial market involved. Attention is given to details regarding the economics of phased arrays, a possible key to improved solutions to phased array construction and operation, the employment of the techniques of photolithography in the fabrication of a transversely-developed array, the need for manufacturing techniques to incorporate magnetic or electroacoustic control devices into the array, problems of heat generation, small mm-wave arrays, questions of reliability, and integrated antennas.

  20. Precision digital pulse phase generator

    DOEpatents

    McEwan, T.E.

    1996-10-08

    A timing generator comprises a crystal oscillator connected to provide an output reference pulse. A resistor-capacitor combination is connected to provide a variable-delay output pulse from an input connected to the crystal oscillator. A phase monitor is connected to provide duty-cycle representations of the reference and variable-delay output pulse phase. An operational amplifier drives a control voltage to the resistor-capacitor combination according to currents integrated from the phase monitor and injected into summing junctions. A digital-to-analog converter injects a control current into the summing junctions according to an input digital control code. A servo equilibrium results that provides a phase delay of the variable-delay output pulse to the output reference pulse that linearly depends on the input digital control code. 2 figs.

  1. Precision digital pulse phase generator

    DOEpatents

    McEwan, Thomas E.

    1996-01-01

    A timing generator comprises a crystal oscillator connected to provide an output reference pulse. A resistor-capacitor combination is connected to provide a variable-delay output pulse from an input connected to the crystal oscillator. A phase monitor is connected to provide duty-cycle representations of the reference and variable-delay output pulse phase. An operational amplifier drives a control voltage to the resistor-capacitor combination according to currents integrated from the phase monitor and injected into summing junctions. A digital-to-analog converter injects a control current into the summing junctions according to an input digital control code. A servo equilibrium results that provides a phase delay of the variable-delay output pulse to the output reference pulse that linearly depends on the input digital control code.

  2. Phase modulating the Urbana radar

    NASA Technical Reports Server (NTRS)

    Herrington, L. J., Jr.; Bowhill, S. A.

    1983-01-01

    The design and operation of a switched phase modulation system for the Urbana Radar System are discussed. The system is implemented and demonstrated using a simple procedure. The radar system and circuits are described and analyzed.

  3. Safety performance of traffic phases and phase transitions in three phase traffic theory.

    PubMed

    Xu, Chengcheng; Liu, Pan; Wang, Wei; Li, Zhibin

    2015-12-01

    Crash risk prediction models were developed to link safety to various phases and phase transitions defined by the three phase traffic theory. Results of the Bayesian conditional logit analysis showed that different traffic states differed distinctly with respect to safety performance. The random-parameter logit approach was utilized to account for the heterogeneity caused by unobserved factors. The Bayesian inference approach based on the Markov Chain Monte Carlo (MCMC) method was used for the estimation of the random-parameter logit model. The proposed approach increased the prediction performance of the crash risk models as compared with the conventional logit model. The three phase traffic theory can help us better understand the mechanism of crash occurrences in various traffic states. The contributing factors to crash likelihood can be well explained by the mechanism of phase transitions. We further discovered that the free flow state can be divided into two sub-phases on the basis of safety performance, including a true free flow state in which the interactions between vehicles are minor, and a platooned traffic state in which bunched vehicles travel in successions. The results of this study suggest that a safety perspective can be added to the three phase traffic theory. The results also suggest that the heterogeneity between different traffic states should be considered when estimating the risks of crash occurrences on freeways. PMID:26367463

  4. Phase relationship in three-phase composites which include a void phase

    NASA Technical Reports Server (NTRS)

    Price, H. L.; Nelson, J. B.

    1976-01-01

    The paper shows the relationship among polymer, particles, and voids in a three-phase composite and how some of the properties of a composite may be changed by changing the proportions of the phases. The three-phase composite is an aggregate of microspheres bonded together with a small amount of polymer which may not form a continuous matrix. The void space (third phase) is obtained by limiting the amount of polymer which is mixed with the microspheres. A ternary phase diagram is used to show the proportional relationship among the three phases, with each apex representing a volume fraction of unity for a constituent while the side opposite the apex represents a volume fraction of zero for that constituent. The vertical dimension represents some composite property such as density or strength. The effect of composition on composite properties is shown by plotting them on a binary phase diagram which represents a perpendicular plane coincident with the 0.60 volume fraction microsphere line.

  5. Phased arrays 1985 symposium: Proceedings

    NASA Astrophysics Data System (ADS)

    Steyskal, H. P.

    1985-08-01

    The Phased Arrays '85 Symposium, sponsored by the Rome Air Development Center, the MITRE Corporation, and the University of Massachusetts, was held at the MITRE Corporation 15 to 18 October and reviewed the state-of-the-art of phased array antenna systems and of the technology for next generation systems. This report contains the full papers which were presented with clearance for unlimited distribution.

  6. Interfacial phase-change memory.

    PubMed

    Simpson, R E; Fons, P; Kolobov, A V; Fukaya, T; Krbal, M; Yagi, T; Tominaga, J

    2011-08-01

    Phase-change memory technology relies on the electrical and optical properties of certain materials changing substantially when the atomic structure of the material is altered by heating or some other excitation process. For example, switching the composite Ge(2)Sb(2)Te(5) (GST) alloy from its covalently bonded amorphous phase to its resonantly bonded metastable cubic crystalline phase decreases the resistivity by three orders of magnitude, and also increases reflectivity across the visible spectrum. Moreover, phase-change memory based on GST is scalable, and is therefore a candidate to replace Flash memory for non-volatile data storage applications. The energy needed to switch between the two phases depends on the intrinsic properties of the phase-change material and the device architecture; this energy is usually supplied by laser or electrical pulses. The switching energy for GST can be reduced by limiting the movement of the atoms to a single dimension, thus substantially reducing the entropic losses associated with the phase-change process. In particular, aligning the c-axis of a hexagonal Sb(2)Te(3) layer and the 〈111〉 direction of a cubic GeTe layer in a superlattice structure creates a material in which Ge atoms can switch between octahedral sites and lower-coordination sites at the interface of the superlattice layers. Here we demonstrate GeTe/Sb(2)Te(3) interfacial phase-change memory (IPCM) data storage devices with reduced switching energies, improved write-erase cycle lifetimes and faster switching speeds. PMID:21725305

  7. Active membrane phased array radar

    NASA Technical Reports Server (NTRS)

    Moussessian, Alina; Del Castillo, Linda; Huang, John; Sadowy, Greg; Hoffman, James; Smith, Phil; Hatake, Toshiro; Derksen, Chuck; Lopez, Bernardo; Caro, Ed

    2005-01-01

    We have developed the first membrane-based active phased array in L-band (1.26GHz). The array uses membrane compatible Transmit/Receive (T/R) modules (membrane T/R) for each antenna element. We use phase shifters within each T/R module for electronic beam steering. We will discuss the T/R module design and integration with the membrane, We will also present transmit and receive beam-steering results for the array.

  8. Reinforced ceramics employing discontinuous phases

    SciTech Connect

    Becher, P.F.

    1990-01-01

    The fracture toughness of ceramics can be improved by the incorporation of a variety of discontinuous reinforcing phases and microstructures. Observations of crack paths in these systems indicate that these reinforcing phases bridge the crack tip wake region. Recent developments in micromechanics toughening models applicable to such systems are discussed and compared with experimental observations. Because material parameters and microstructural characteristics are considered, the crack bridging models provide a means to optimize the toughening effects. 18 refs., 2 figs.

  9. Berry Phase in Lattice QCD.

    PubMed

    Yamamoto, Arata

    2016-07-29

    We propose the lattice QCD calculation of the Berry phase, which is defined by the ground state of a single fermion. We perform the ground-state projection of a single-fermion propagator, construct the Berry link variable on a momentum-space lattice, and calculate the Berry phase. As the first application, the first Chern number of the (2+1)-dimensional Wilson fermion is calculated by the Monte Carlo simulation. PMID:27517766

  10. Phase transitions in nuclear matter

    SciTech Connect

    Glendenning, N.K.

    1984-11-01

    The rather general circumstances under which a phase transition in hadronic matter at finite temperature to an abnormal phase in which baryon effective masses become small and in which copious baryon-antibaryon pairs appear is emphasized. A preview is also given of a soliton model of dense matter, in which at a density of about seven times nuclear density, matter ceases to be a color insulator and becomes increasingly color conducting. 22 references.

  11. Describing phase coexistence in systems with small phases

    NASA Astrophysics Data System (ADS)

    Lovett, R.

    2007-02-01

    Clusters of atoms can be studied in molecular beams and by computer simulation; 'liquid drops' provide elementary models for atomic nuclei and for the critical nuclei of nucleation theory. These clusters are often described in thermodynamic terms, but the behaviour of small clusters near a phase boundary is qualitatively different from the behaviour at a first order phase transition in idealized thermodynamics. In the idealized case the density and entropy show mathematically sharp discontinuities when the phase boundary is crossed. In large, but finite, systems, the phase boundaries become regions of state space wherein these properties vary rapidly but continuously. In small clusters with a large surface/volume ratio, however, the positive interfacial free energy makes it unlikely, even in states on phase boundaries, that a cluster will have a heterogeneous structure. What is actually seen in these states is a structure that fluctuates in time between homogeneous structures characteristic of the two sides of the phase boundary. That is, structural fluctuations are observed. Thermodynamics only predicts average properties; statistical mechanics is required to understand these fluctuations. Failure to distinguish thermodynamic properties and characterizations of fluctuations, particularly in the context of first order phase transitions, has led to suggestions that the classical rules for thermodynamic stability are violated in small systems and that classical thermodynamics provides an inconsistent description of these systems. Much of the confusion stems from taking statistical mechanical identifications of thermodynamic properties, explicitly developed for large systems, and applying them uncritically to small systems. There are no inconsistencies if thermodynamic properties are correctly identified and the distinction between thermodynamic properties and fluctuations is made clear.

  12. Phase variation of hadronic amplitudes

    SciTech Connect

    Dedonder, J.-P.; Gibbs, W. R.; Nuseirat, Mutazz

    2008-04-15

    The phase variation with angle of hadronic amplitudes is studied with a view to understanding the underlying physical quantities that control it and how well it can be determined in free space. We find that unitarity forces a moderately accurate determination of the phase in standard amplitude analyses but that the nucleon-nucleon analyses done to date do not give the phase variation needed to achieve a good representation of the data in multiple scattering calculations. Models are examined that suggest its behavior near forward angles is related to the radii of the real and absorptive parts of the interaction. The dependence of this phase on model parameters is such that if these radii are modified in the nuclear medium (in combination with the change due to the shift in energy of the effective amplitude in the medium) then the larger magnitudes of the phase needed to fit the data might be attainable but only for negative values of the phase variation parameter.

  13. Phase Diagrams of Nuclear Pasta

    NASA Astrophysics Data System (ADS)

    Caplan, Matthew; Horowitz, Chuck; Berry, Don; da Silva Schneider, Andre

    2016-03-01

    In the inner crust of neutrons stars, where matter is near the saturation density, protons and neutrons arrange themselves into complex structures called nuclear pasta. Early theoretical work predicted a simple graduated hierarchy of pasta phases, consisting of spheres, cylinders, slabs, and uniform matter with voids. Previous work has simulated these phases with a simple classical model and has shown that the formation of these structures is dependent on the temperature, density, and proton fraction. However, previous work only studied a limited range of these parameters due to computational limitations. Thanks to recent advances in computing it is now possible to survey the structure of nuclear pasta for a larger range of parameters. By simulating nuclear pasta with constant temperature and proton fraction in an expanding simulation volume we are able to study the phase transitions in nuclear pasta, and thus produce a set of phase diagrams. We report on these phase diagrams as well as newly identified phases of nuclear pasta and discuss their implications for neutron star observables.

  14. Higher-dimensional phase imaging

    NASA Astrophysics Data System (ADS)

    Huntley, Jonathan M.

    2010-04-01

    Traditional full-field interferometric techniques (speckle, moiré, holography etc) provide 2-D phase images, which encode the surface deformation state of the object under test. Over the past 15 years, the use of additional spatial or temporal dimensions has been investigated by a number of research groups. Early examples include the measurement of 3-D surface profiles by temporally-varying projected fringe patterns, and dynamic speckle interferometry. More recently (the past 5 years) a family of related techniques (Wavelength Scanning Interferometry, Phase Contrast Spectral Optical Coherence Tomography (OCT), and Tilt Scanning Interferometry) has emerged that provides the volume deformation state of the object. The techniques can be thought of as a marriage between the phase sensing capabilities of Phase Shifting Interferometry and the depth-sensing capabilities of OCT. Finally, in the past 12 months a technique called Hyperspectral Interferometry has been proposed in which absolute optical path distributions are obtained in a single shot through the spectral decomposition of a white light interferogram, and for which the additional dimension therefore corresponds to the illumination wavenumber. An overview of these developments, and the related issue of robust phase unwrapping of noisy 3-D wrapped phase volumes, is presented in this paper.

  15. Phase modulation in RF tag

    DOEpatents

    Carrender, Curtis Lee; Gilbert, Ronald W.

    2007-02-20

    A radio frequency (RF) communication system employs phase-modulated backscatter signals for RF communication from an RF tag to an interrogator. The interrogator transmits a continuous wave interrogation signal to the RF tag, which based on an information code stored in a memory, phase-modulates the interrogation signal to produce a backscatter response signal that is transmitted back to the interrogator. A phase modulator structure in the RF tag may include a switch coupled between an antenna and a quarter-wavelength stub; and a driver coupled between the memory and a control terminal of the switch. The driver is structured to produce a modulating signal corresponding to the information code, the modulating signal alternately opening and closing the switch to respectively decrease and increase the transmission path taken by the interrogation signal and thereby modulate the phase of the response signal. Alternatively, the phase modulator may include a diode coupled between the antenna and driver. The modulating signal from the driver modulates the capacitance of the diode, which modulates the phase of the response signal reflected by the diode and antenna.

  16. Stochastic phase-change neurons

    NASA Astrophysics Data System (ADS)

    Tuma, Tomas; Pantazi, Angeliki; Le Gallo, Manuel; Sebastian, Abu; Eleftheriou, Evangelos

    2016-08-01

    Artificial neuromorphic systems based on populations of spiking neurons are an indispensable tool in understanding the human brain and in constructing neuromimetic computational systems. To reach areal and power efficiencies comparable to those seen in biological systems, electroionics-based and phase-change-based memristive devices have been explored as nanoscale counterparts of synapses. However, progress on scalable realizations of neurons has so far been limited. Here, we show that chalcogenide-based phase-change materials can be used to create an artificial neuron in which the membrane potential is represented by the phase configuration of the nanoscale phase-change device. By exploiting the physics of reversible amorphous-to-crystal phase transitions, we show that the temporal integration of postsynaptic potentials can be achieved on a nanosecond timescale. Moreover, we show that this is inherently stochastic because of the melt-quench-induced reconfiguration of the atomic structure occurring when the neuron is reset. We demonstrate the use of these phase-change neurons, and their populations, in the detection of temporal correlations in parallel data streams and in sub-Nyquist representation of high-bandwidth signals.

  17. Stochastic phase-change neurons.

    PubMed

    Tuma, Tomas; Pantazi, Angeliki; Le Gallo, Manuel; Sebastian, Abu; Eleftheriou, Evangelos

    2016-08-01

    Artificial neuromorphic systems based on populations of spiking neurons are an indispensable tool in understanding the human brain and in constructing neuromimetic computational systems. To reach areal and power efficiencies comparable to those seen in biological systems, electroionics-based and phase-change-based memristive devices have been explored as nanoscale counterparts of synapses. However, progress on scalable realizations of neurons has so far been limited. Here, we show that chalcogenide-based phase-change materials can be used to create an artificial neuron in which the membrane potential is represented by the phase configuration of the nanoscale phase-change device. By exploiting the physics of reversible amorphous-to-crystal phase transitions, we show that the temporal integration of postsynaptic potentials can be achieved on a nanosecond timescale. Moreover, we show that this is inherently stochastic because of the melt-quench-induced reconfiguration of the atomic structure occurring when the neuron is reset. We demonstrate the use of these phase-change neurons, and their populations, in the detection of temporal correlations in parallel data streams and in sub-Nyquist representation of high-bandwidth signals. PMID:27183057

  18. KERNEL PHASE IN FIZEAU INTERFEROMETRY

    SciTech Connect

    Martinache, Frantz

    2010-11-20

    The detection of high contrast companions at small angular separation appears feasible in conventional direct images using the self-calibration properties of interferometric observable quantities. The friendly notion of closure phase, which is key to the recent observational successes of non-redundant aperture masking interferometry used with adaptive optics, appears to be one example of a wide family of observable quantities that are not contaminated by phase noise. In the high-Strehl regime, soon to be available thanks to the coming generation of extreme adaptive optics systems on ground-based telescopes, and already available from space, closure phase like information can be extracted from any direct image, even taken with a redundant aperture. These new phase-noise immune observable quantities, called kernel phases, are determined a priori from the knowledge of the geometry of the pupil only. Re-analysis of archive data acquired with the Hubble Space Telescope NICMOS instrument using this new kernel-phase algorithm demonstrates the power of the method as it clearly detects and locates with milliarcsecond precision a known companion to a star at angular separation less than the diffraction limit.

  19. Toxicity and composition profiles of solid phase extracts of oil sands process-affected water.

    PubMed

    Yue, Siqing; Ramsay, Bruce A; Wang, Jiaxi; Ramsay, Juliana

    2015-12-15

    After fractionation using sequential solid phase extraction, the presence of toxic components in oil sands process-affected water (OSPW) was detected by the Microtox® acute toxicity assay using effect-directed analysis. The composition of each fraction was determined by high-resolution electrospray ionization-Orbitrap mass spectrometry. Partial least-squares discriminant analysis (PLS-DA) was used to determine which chemical constituents in all seven fractions co-varied most strongly with toxicity. Although O2 compounds with double bond equivalence (DBE) between 3 and 9 positively correlated with toxicity, C15-C18 O2-NAs with DBE=4 (tricyclic structure), as well as C14-C17 O2-NAs with DBE=3 (bicyclic structure), were found to be most likely associated with OSPW toxicity, consistent with published toxicity studies of surrogate NAs. O4, many O3 (i.e. possibly hydroxylated O2 c-NAs) and a few O2 compounds were found to negatively correlate with toxicity. The results demonstrate the utility of the fractionation and the PLS-DA approach for evaluating composition-response relationships in a complex mixture and also contribute to a better understanding of the toxic compounds in OSPW. These findings will help to focus study on the most environmentally significant components in OSPW. PMID:26318810

  20. Jahn-Teller solitons, structural phase transitions, and phase separation.

    PubMed

    Clougherty, Dennis P

    2006-02-01

    It is demonstrated that under common conditions a molecular solid subject to Jahn-Teller interactions supports stable Q-ball-like nontopological solitons. Such solitons represent a localized lump of excess electric charge in periodic motion accompanied by a time-dependent shape distortion of a set of adjacent molecules. The motion of the distortion can correspond to a true rotation or to a pseudorotation about the symmetric shape configuration. These solitons are stable for Jahn-Teller coupling strengths below a critical value; however, as the Jahn-Teller coupling approaches this critical value, the size of the soliton diverges signaling an incipient structural phase transition. The soliton phase mimics features commonly attributed to phase separation in complex solids. PMID:16486846

  1. Jahn-Teller Solitons, Structural Phase Transitions, and Phase Separation

    NASA Astrophysics Data System (ADS)

    Clougherty, Dennis P.

    2006-02-01

    It is demonstrated that under common conditions a molecular solid subject to Jahn-Teller interactions supports stable Q-ball-like nontopological solitons. Such solitons represent a localized lump of excess electric charge in periodic motion accompanied by a time-dependent shape distortion of a set of adjacent molecules. The motion of the distortion can correspond to a true rotation or to a pseudorotation about the symmetric shape configuration. These solitons are stable for Jahn-Teller coupling strengths below a critical value; however, as the Jahn-Teller coupling approaches this critical value, the size of the soliton diverges signaling an incipient structural phase transition. The soliton phase mimics features commonly attributed to phase separation in complex solids.

  2. Phases and phase transitions in the algebraic microscopic shell model

    NASA Astrophysics Data System (ADS)

    Georgieva, A. I.; Drumev, K. P.

    2016-01-01

    We explore the dynamical symmetries of the shell model number conserving algebra, which define three types of pairing and quadrupole phases, with the aim to obtain the prevailing phase or phase transition for the real nuclear systems in a single shell. This is achieved by establishing a correspondence between each of the pairing bases with the Elliott's SU(3) basis that describes collective rotation of nuclear systems. This allows for a complete classification of the basis states of different number of particles in all the limiting cases. The probability distribution of the SU(3) basis states within theirs corresponding pairing states is also obtained. The relative strengths of dynamically symmetric quadrupole-quadrupole interaction in respect to the isoscalar, isovector and total pairing interactions define a control parameter, which estimates the importance of each term of the Hamiltonian in the correct reproduction of the experimental data for the considered nuclei.

  3. Phase-Locked Loop Noise Reduction via Phase Detector Implementation for Single-Phase Systems

    SciTech Connect

    Thacker, Timothy; Boroyevich, Dushan; Burgos, Rolando; Wang, Fei

    2011-01-01

    A crucial component of grid-connected converters is the phase-locked loop (PLL) control subsystem that tracks the grid voltage's frequency and phase angle. Therefore, accurate fast-responding PLLs for control and protection purposes are required to provide these measurements. This paper proposes a novel feedback mechanism for single-phase PLL phase detectors using the estimated phase angle. Ripple noise appearing in the estimated frequency, most commonly the second harmonic under phase-lock conditions, is reduced or eliminated without the use of low-pass filters, which can cause delays to occur and limits the overall performance of the PLL response to dynamic changes in the system. The proposed method has the capability to eliminate the noise ripple entirely and, under extreme line distortion conditions, can reduce the ripple by at least half. Other modifications implemented through frequency feedback are shown to decrease the settling time of the PLL up to 50%. Mathematical analyses with the simulated and experimental results are provided to confirm the validity of the proposed methods.

  4. The comfortable driving model revisited: traffic phases and phase transitions

    NASA Astrophysics Data System (ADS)

    Knorr, Florian; Schreckenberg, Michael

    2013-07-01

    We study the spatiotemporal patterns resulting from different boundary conditions for a microscopic traffic model and contrast them with empirical results. By evaluating the time series of local measurements, the local traffic states are assigned to the different traffic phases of Kerner’s three-phase traffic theory. For this classification we use the rule-based FOTO-method, which provides ‘hard’ rules for this assignment. Using this approach, our analysis shows that the model is indeed able to reproduce three qualitatively different traffic phases: free flow (F), synchronized traffic (S), and wide moving jams (J). In addition, we investigate the likelihood of transitions between the three traffic phases. We show that a transition from free flow to a wide moving jam often involves an intermediate transition: first from free flow to synchronized flow and then from synchronized flow to a wide moving jam. This is supported by the fact that the so-called F → S transition (from free flow to synchronized traffic) is much more likely than a direct F → J transition. The model under consideration has a functional relationship between traffic flow and traffic density. The fundamental hypothesis of the three-phase traffic theory, however, postulates that the steady states of synchronized flow occupy a two-dimensional region in the flow-density plane. Due to the obvious discrepancy between the model investigated here and the postulate of the three-phase traffic theory, the good agreement that we found could not be expected. For a more detailed analysis, we also studied vehicle dynamics at a microscopic level and provide a comparison of real detector data with simulated data of the identical highway segment.

  5. Phase Correction for GPS Antenna with Nonunique Phase Center

    NASA Technical Reports Server (NTRS)

    Fink, Patrick W.; Dobbins, Justin

    2005-01-01

    A method of determining the position and attitude of a body equipped with a Global Positioning System (GPS) receiver includes an accounting for the location of the nonunique phase center of a distributed or wraparound GPS antenna. The method applies, more specifically, to the case in which (1) the GPS receiver utilizes measurements of the phases of GPS carrier signals in its position and attitude computations and (2) the body is axisymmetric (e.g., spherical or round cylindrical) and wrapped at its equator with a single- or multiple-element antenna, the radiation pattern of which is also axisymmetric with the same axis of symmetry as that of the body.

  6. Digital optical phase control in ridge-waveguide phase modulators

    SciTech Connect

    Vawter, G.A.; Hietala, V.M.; Kravitz, S.H. )

    1993-03-01

    The authors report a new digital optical phase modulation concept based on depletion-edge-translation p-n junction GaAs/AlGaAs ridge-waveguide modulators. Digital modulation is achieved by integrating in series several discrete waveguide modulators with lengths related by successive factors of two. To illustrate the concept, the authors fabricated and demonstrated a three-bit digital phase modulator with 45[degree] resolution. This structure represents the first photonic integrated circuit that performs direct digital-electronic to analog-optical conversion.

  7. Differential phase shift keyed signal resolver

    NASA Technical Reports Server (NTRS)

    Hopkins, P. M.; Wallingford, W. M. (Inventor)

    1974-01-01

    A differential phase shift keyed signal resolver resolves the differential phase shift in the incoming signal to determine the data content thereof overcoming phase uncertainty without requiring a transmitted reference signal.

  8. Tracking a phase-shift-keyed signal

    NASA Technical Reports Server (NTRS)

    Villarreal, S.; Lenett, S. D.; Kobayashi, H. S.; Pawlowski, J. F.

    1977-01-01

    In detector, phase shifter is used to generate negative phase shift opposing detected phase angle. This produces converted series sideband and component carrier, with residual carrier signal and converted series sideband and component carrier added together to produce tracking signal.

  9. Phase measurement system using a dithered clock

    DOEpatents

    Fairley, C.R.; Patterson, S.R.

    1991-05-28

    A phase measurement system is disclosed which measures the phase shift between two signals by dithering a clock signal and averaging a plurality of measurements of the phase differences between the two signals. 8 figures.

  10. Compact nanomechanical plasmonic phase modulators

    SciTech Connect

    Dennis, B. S.; Haftel, M. I.; Czaplewski, D. A.; Lopez, D.; Blumberg, G.; Aksyuk, V. A.

    2015-03-30

    Highly confined optical energy in plasmonic devices is advancing miniaturization in photonics. However, for mode sizes approaching ≈10 nm, the energy increasingly shifts into the metal, raising losses and hindering active phase modulation. Here, we propose a nanoelectromechanical phase-modulation principle exploiting the extraordinarily strong dependence of the phase velocity of metal–insulator–metal gap plasmons on dynamically variable gap size. We experimentally demonstrate a 23-μm-long non-resonant modulator having a 1.5π rad range, with 1.7 dB excess loss at 780 nm. Analysis shows that by simultaneously decreasing the gap, length and width, an ultracompact-footprint π rad phase modulator can be realized. This is achieved without incurring the extra loss expected for plasmons confined in a decreasing gap, because the increasing phase-modulation strength from a narrowing gap offsets rising propagation losses. Such small, high-density electrically controllable components may find applications in optical switch fabrics and reconfigurable plasmonic optics.

  11. Optimal Electrodynamic Tether Phasing Maneuvers

    NASA Technical Reports Server (NTRS)

    Bitzer, Matthew S.; Hall, Christopher D.

    2007-01-01

    We study the minimum-time orbit phasing maneuver problem for a constant-current electrodynamic tether (EDT). The EDT is assumed to be a point mass and the electromagnetic forces acting on the tether are always perpendicular to the local magnetic field. After deriving and non-dimensionalizing the equations of motion, the only input parameters become current and the phase angle. Solution examples, including initial Lagrange costates, time of flight, thrust plots, and thrust angle profiles, are given for a wide range of current magnitudes and phase angles. The two-dimensional cases presented use a non-tilted magnetic dipole model, and the solutions are compared to existing literature. We are able to compare similar trajectories for a constant thrust phasing maneuver and we find that the time of flight is longer for the constant thrust case with similar initial thrust values and phase angles. Full three-dimensional solutions, which use a titled magnetic dipole model, are also analyzed for orbits with small inclinations.

  12. Phase-sensitive flow cytometer

    SciTech Connect

    Steinkamp, J.A.; Martin, J.C.; Crissman, H.A. )

    1993-01-01

    A phase-sensitive flow cytometer has been developed that combines flow cytometry and fluorescence spectroscopy measurement principles to provide unique capabilities for making phase-resolved measurements on single cells. Stained cells are analyzed as they intersect an intensity-modulated (sinusoid) laser beam. Fluorescence is measured using only a collecting lens, a longpass filter, and a photomultiplier tube detector. Signals are processed by phase-sensitive detection electronics to resolve signals from heterogeneous emissions and quantify decay lifetimes. Results have demonstrated: (1) signal phase shift and amplitude demodulation on fluorospheres and PI-stained cells; (2) a detection threshold of 800-300 fluorescein molecules equivalence for excitation frequencies 10 to 30 MHz; (3) measurement precision of 1.5% on fluorospheres and 4.0% on Pi-stained cells; (4) the resolution of Pi and FITC signals based on differences in their lifetimes; and (5) the measurement of single decay lifetimes by the two-phase ratio method. The significance of this new technology is that the number of fluorochromes usable in multilabeling experiments will be increased; background interferences (autofluorescence, unbound dye, nonspecific staining, Raman scatter) will be eliminated; and fluorescence lifetime can be quantified to study the interaction of fluorochrome binding.

  13. High speed moire based phase retrieval method for quantitative phase imaging of thin objects without phase unwrapping or aberration compensation

    NASA Astrophysics Data System (ADS)

    Wang, Shouyu; Yan, Keding; Xue, Liang

    2016-01-01

    Phase retrieval composed of phase extracting and unwrapping is of great significance in different occasions, such as fringe projection based profilometry, quantitative interferometric microscopy and moire detections. Compared to phase extracting, phase unwrapping occupies most time consuming in phase retrieval, and it becomes an obstacle to realize real time measurements. In order to increase the calculation efficiency of phase retrieval as well as simplify its procedures, here, a high speed moire based phase retrieval method is proposed which is capable of calculating quantitative phase distributions without phase unwrapping or aberration compensation. We demonstrate the capability of the presented phase retrieval method by both theoretical analysis and experiments. It is believed that the proposed method will be useful in real time phase observations and measurements.

  14. Phase Transformations in Confined Nanosystems

    SciTech Connect

    Shield, Jeffrey E.; Belashchenko, Kirill

    2014-04-29

    This project discovered that non-equilibrium structures, including chemically ordered structures not observed in bulk systems, form in isolated nanoscale systems. Further, a generalized model was developed that effectively explained the suppression of equilibrium phase transformations. This thermodynamic model considered the free energy decrease associated with the phase transformation was less than the increase in energy associated with the formation of an interphase interface, therefore inhibiting the phase transformation. A critical diameter exists where the system transitions to bulk behavior, and a generalized equation was formulated that successfully predicted this transition in the Fe-Au system. This provided and explains a new route to novel structures not possible in bulk systems. The structural characterization was accomplished using transmission electron microscopy in collaboration with Matthew Kramer of Ames Laboratory. The PI and graduate student visited Ames Laboratory several times a year to conduct the experiments.

  15. GPC and quantitative phase imaging

    NASA Astrophysics Data System (ADS)

    Palima, Darwin; Bañas, Andrew Rafael; Villangca, Mark Jayson; Glückstad, Jesper

    2016-03-01

    Generalized Phase Contrast (GPC) is a light efficient method for generating speckle-free contiguous optical distributions using binary-only or analog phase levels. It has been used in applications such as optical trapping and manipulation, active microscopy, structured illumination, optical security, parallel laser marking and labelling and recently in contemporary biophotonics applications such as for adaptive and parallel two-photon optogenetics and neurophotonics. We will present our most recent GPC developments geared towards these applications. We first show a very compact static light shaper followed by the potential of GPC for biomedical and multispectral applications where we experimentally demonstrate the active light shaping of a supercontinuum laser over most of the visible wavelength range. Finally, we discuss how GPC can be advantageously applied for Quantitative Phase Imaging (QPI).

  16. Griffiths Phases on Complex Networks

    NASA Astrophysics Data System (ADS)

    Muñoz, Miguel A.; Juhász, Róbert; Castellano, Claudio; Ódor, Géza

    2010-09-01

    Quenched disorder is known to play a relevant role in dynamical processes and phase transitions. Its effects on the dynamics of complex networks have hardly been studied. Aimed at filling this gap, we analyze the contact process, i.e., the simplest propagation model, with quenched disorder on complex networks. We find Griffiths phases and other rare-region effects, leading rather generically to anomalously slow (algebraic, logarithmic, …) relaxation, on Erdős-Rényi networks. Similar effects are predicted to exist for other topologies with a finite percolation threshold. More surprisingly, we find that Griffiths phases can also emerge in the absence of quenched disorder, as a consequence of topological heterogeneity in networks with finite topological dimension. These results have a broad spectrum of implications for propagation phenomena and other dynamical processes on networks.

  17. Phase preservation in musical signals

    NASA Astrophysics Data System (ADS)

    Vijayakumar, V.; Eswaran, C.

    2005-04-01

    The intensity variations of the harmonics of musical instruments in the frequency domain can be interpreted to store phase information. The motivation for this arises by considering the similarity of the timbre of in- struments to that obtained through a diffraction model proposed here. The intensity modifications of an input spectrum of discrete frequencies of unit intensity into the known spectra of different musical instruments have been found to match that of known instruments. According to diffraction theory, the modifying envelope encodes phase information. By considering the similarity, it is proposed that musical instrument timbre store phase information. It is suggested that timbre itself could have diffraction origins. Specific examples of musical instruments are considered to illustrate this intepretation.

  18. SXLS Phase 2 vacuum system

    SciTech Connect

    Schuchman, J.C.; Chou, T.S.; Halama, H.; Hsieh, H.; Kim, T.; Pjerov, S.; Staicu, F.

    1991-01-01

    Phase 1 of the SXLS (Superconducting X-Ray Lithography Source) is described. It is a room temperature, racetrack-shaped electron storage ring, 8.5 meters in circumference. The Phase 2 design consists of replacing the two room temperature 180{degree} dipole magnets of Phase 1 with superconducting magnets. However, even though superconducting magnets are used, the vacuum chambers within them will operate at room temperature. The chambers are constructed as weldments and are made of INCONEL-625. They are bakeable to 150{degrees}C in-situ and incorporate nine photon beam ports. Each have built-in distributed sputter-ion pumps (DIP), non-evaporable getter (NEG) pumps, beam position monitors, and ion clearing electrodes. R D is underway to optimize the DIP, which much operate at 3.86 Tesla, and to develop a low photo yield coating or treatment for the internal surfaces of the chambers.

  19. Sub-Heisenberg phase uncertainties

    NASA Astrophysics Data System (ADS)

    Pezzé, Luca

    2013-12-01

    Phase shift estimation with uncertainty below the Heisenberg limit, ΔϕHL∝1/N¯T, where N¯T is the total average number of particles employed, is a mirage of linear quantum interferometry. Recently, Rivas and Luis, [New J. Phys.NJOPFM1367-263010.1088/1367-2630/14/9/093052 14, 093052 (2012)] proposed a scheme to achieve a phase uncertainty Δϕ∝1/N¯Tk, with k an arbitrary exponent. This sparked an intense debate in the literature which, ultimately, does not exclude the possibility to overcome ΔϕHL at specific phase values. Our numerical analysis of the Rivas and Luis proposal shows that sub-Heisenberg uncertainties are obtained only when the estimator is strongly biased. No violation of the Heisenberg limit is found after bias correction or when using a bias-free Bayesian analysis.

  20. Phase diagram of ammonium nitrate

    NASA Astrophysics Data System (ADS)

    Dunuwille, M.; Yoo, C. S.

    2014-05-01

    Ammonium Nitrate (AN) has often subjected to uses in improvised explosive devices, due to its wide availability as a fertilizer and its capability of becoming explosive with slight additions of organic and inorganic compounds. Yet, the origin of enhanced energetic properties of impure AN (or AN mixtures) is neither chemically unique nor well understood -resulting in rather catastrophic disasters in the past1 and thereby a significant burden on safety in using ammonium nitrates even today. To remedy this situation, we have carried out an extensive study to investigate the phase stability of AN at high pressure and temperature, using diamond anvil cells and micro-Raman spectroscopy. The present results confirm the recently proposed phase IV-to-IV' transition above 17 GPa2 and provide new constraints for the melting and phase diagram of AN to 40 GPa and 400 °C.

  1. Propeller speed and phase sensor

    NASA Technical Reports Server (NTRS)

    Collopy, Paul D. (Inventor); Bennett, George W. (Inventor)

    1992-01-01

    A speed and phase sensor counterrotates aircraft propellers. A toothed wheel is attached to each propeller, and the teeth trigger a sensor as they pass, producing a sequence of signals. From the sequence of signals, rotational speed of each propeller is computer based on time intervals between successive signals. The speed can be computed several times during one revolution, thus giving speed information which is highly up-to-date. Given that spacing between teeth may not be uniform, the signals produced may be nonuniform in time. Error coefficients are derived to correct for nonuniformities in the resulting signals, thus allowing accurate speed to be computed despite the spacing nonuniformities. Phase can be viewed as the relative rotational position of one propeller with respect to the other, but measured at a fixed time. Phase is computed from the signals.

  2. Renovating and Reconstructing in Phases--Specifying Phased Construction.

    ERIC Educational Resources Information Center

    Bunzick, John

    2002-01-01

    Discusses planning for phased school construction projects, including effects on occupancy (for example, construction adjacent to occupied space, construction procedure safety zones near occupied areas, and code-complying means of egress), effects on building systems (such as heating and cooling equipment and power distribution), and contract…

  3. Phase behaviour and phase separation kinetics measurement using acoustic arrays

    NASA Astrophysics Data System (ADS)

    Khammar, M.; Shaw, J. M.

    2011-10-01

    Speed of sound and acoustic wave attenuation are sensitive to fluid phase composition and to the presence of liquid-liquid interfaces. In this work, the use of an acoustic array comprising 64 elements as a non-intrusive sensor for liquid-liquid interface, phase separation kinetics measurement in bulk fluids, and local composition measurement in porous media is illustrated. Three benchmark examples: the phase behaviour of methanol + mixed hexanes and methanol + heptane mixtures at 25.0 °C and 1 bar, and Athabasca bitumen + heptane in a synthetic silica porous medium at 22.5 °C and 1 bar, illustrate the accuracy of liquid-liquid interface and potential research and industrial applications of the technique. Liquid-liquid interfaces can be detected independently using both speed of sound and acoustic wave attenuation measurements. The precision of the interface location measurement is 300 μm. As complete scans can be performed at a rate of 1 Hz, phase separation kinetics and diffusion of liquids within porous media are readily tracked. The technique is expected to find application where the fluids or porous media are opaque to visible light and where other imaging techniques are not readily applied, or are too costly. A current limitation is that the acoustic probes must be cooled to less than 315 K in order for them to operate.

  4. Color deflectometry for phase retrieval using phase-shifting methods

    NASA Astrophysics Data System (ADS)

    Flores, Jorge L.; Legarda-Saenz, Ricardo; Garcia-Torales, G.

    2015-01-01

    In this paper, we propose a technique based on a color fringe pattern used on deflectometry experiment. The advantages of using color fringe patterns together with phase shifting techniques on deflectometry experiment are presented. An experimental wavefront reconstruction of a progressive lens shows the accuracy and simplicity of these techniques used to process the deflection measurements.

  5. Aerothermal modeling program, phase 2

    NASA Technical Reports Server (NTRS)

    Mongia, H. C.; Patankar, S. V.; Murthy, S. N. B.; Sullivan, J. P.; Samuelsen, G. S.

    1985-01-01

    The main objectives of the Aerothermal Modeling Program, Phase 2 are: to develop an improved numerical scheme for incorporation in a 3-D combustor flow model; to conduct a benchmark quality experiment to study the interaction of a primary jet with a confined swirling crossflow and to assess current and advanced turbulence and scalar transport models; and to conduct experimental evaluation of the air swirler interaction with fuel injectors, assessments of current two-phase models, and verification the improved spray evaporation/dispersion models.

  6. Holographic approach to phase transitions

    SciTech Connect

    Franco, Sebastian; Garcia-Garcia, Antonio M.; Rodriguez-Gomez, Diego

    2010-02-15

    We provide a description of phase transitions at finite temperature in strongly coupled field theories using holography. For this purpose, we introduce a general class of gravity duals to superconducting theories that exhibit various types of phase transitions (first or second order with both mean and non-mean field behavior) as parameters in their Lagrangian are changed. Moreover the size and strength of the conductivity coherence peak can also be controlled. Our results suggest that certain parameters in the gravitational dual control the interactions responsible for binding the condensate and the magnitude of its fluctuations close to the transition.

  7. New Instrumentation for Phase Partitioning

    NASA Technical Reports Server (NTRS)

    Harris, J. M.

    1985-01-01

    Cells and molecules can be purified by partitioning between the two immiscible liquid phases formed by aqueous solutions of poly/ethylene glycol and dextran. Such purification can be more selective, higher yielding, and less destructive to sensitive biological materials than other available techniques. Earth's gravitational field is a hindering factor as it causes sedimentation of particles to be purified and shear-induced particle randomization. The present proposal is directed toward developing new instrumentation for performing phase partitioning both on Earth and in microgravity.

  8. Generalized orthogonal wavelet phase reconstruction.

    PubMed

    Axtell, Travis W; Cristi, Roberto

    2013-05-01

    Phase reconstruction is used for feedback control in adaptive optics systems. To achieve performance metrics for high actuator density or with limited processing capabilities on spacecraft, a wavelet signal processing technique is advantageous. Previous derivations of this technique have been limited to the Haar wavelet. This paper derives the relationship and algorithms to reconstruct phase with O(n) computational complexity for wavelets with the orthogonal property. This has additional benefits for performance with noise in the measurements. We also provide details on how to handle the boundary condition for telescope apertures. PMID:23695316

  9. Phase behavior of methane haze.

    PubMed

    Signorell, R; Jetzki, M

    2007-01-01

    Methane aerosols play a fundamental role in the atmospheres of Neptune, Uranus, and Saturn's moon Titan as borne out by the recent Cassini-Huygens mission. Here we present the first study of the phase behavior of free methane aerosol particles combining collisional cooling with rapid-scan infrared spectroscopy in situ. We find fast (within minutes) phase transitions to crystalline states directly after particle formation and characteristic surface effects for nanometer-sized particles. From our results, we conclude that in atmospheric clouds solid methane particles are crystalline. PMID:17358473

  10. Phase dynamics in cerebral autoregulation.

    PubMed

    Latka, Miroslaw; Turalska, Malgorzata; Glaubic-Latka, Marta; Kolodziej, Waldemar; Latka, Dariusz; West, Bruce J

    2005-11-01

    Complex continuous wavelet transforms are used to study the dynamics of instantaneous phase difference delta phi between the fluctuations of arterial blood pressure (ABP) and cerebral blood flow velocity (CBFV) in a middle cerebral artery. For healthy individuals, this phase difference changes slowly over time and has an almost uniform distribution for the very low-frequency (0.02-0.07 Hz) part of the spectrum. We quantify phase dynamics with the help of the synchronization index gamma = (sin delta phi)2 + (cos delta phi)2 that may vary between 0 (uniform distribution of phase differences, so the time series are statistically independent of one another) and 1 (phase locking of ABP and CBFV, so the former drives the latter). For healthy individuals, the group-averaged index gamma has two distinct peaks, one at 0.11 Hz [gamma = 0.59 +/- 0.09] and another at 0.33 Hz (gamma = 0.55 +/- 0.17). In the very low-frequency range (0.02-0.07 Hz), phase difference variability is an inherent property of an intact autoregulation system. Consequently, the average value of the synchronization parameter in this part of the spectrum is equal to 0.13 +/- 0.03. The phase difference variability sheds new light on the nature of cerebral hemodynamics, which so far has been predominantly characterized with the help of the high-pass filter model. In this intrinsically stationary approach, based on the transfer function formalism, the efficient autoregulation is associated with the positive phase shift between oscillations of CBFV and ABP. However, the method is applicable only in the part of the spectrum (0.1-0.3 Hz) where the coherence of these signals is high. We point out that synchrony analysis through the use of wavelet transforms is more general and allows us to study nonstationary aspects of cerebral hemodynamics in the very low-frequency range where the physiological significance of autoregulation is most strongly pronounced. PMID:16024579

  11. Chemical Shift Induced Phase Errors in Phase Contrast MRI

    PubMed Central

    Middione, Matthew J.; Ennis, Daniel B.

    2012-01-01

    Phase contrast magnetic resonance imaging (PC-MRI) is subject to numerous sources of error, which decrease clinical confidence in the reported measures. This work outlines how stationary perivascular fat can impart a significant chemical shift induced PC-MRI measurement error using computational simulations, in vitro, and in vivo experiments. This chemical shift error does not subtract in phase difference processing, but can be minimized with proper parameter selection. The chemical shift induced phase errors largely depend on both the receiver bandwidth (BW) and the TE. Both theory and an in vivo comparison of the maximum difference in net forward flow between vessels with and without perivascular fat indicated that the effects of chemically shifted perivascular fat are minimized by the use of high BW (814 Hz/px) and an in-phase TE (HBW-TEIN). In healthy volunteers (N=10) HBW-TEIN significantly improves intrapatient net forward flow agreement compared to low BW (401 Hz/px) and a mid-phase TE as indicated by significantly decreased measurement biases and limits of agreement for the ascending aorta (1.8±0.5 mL vs. 6.4±2.8 mL, P=0.01), main pulmonary artery (2.0±0.9 mL vs. 11.9±5.8 mL, P=0.04), the left pulmonary artery (1.3±0.9 mL vs. 5.4±2.5 mL, P=0.003), and all vessels (1.7±0.8 mL vs. 7.2±4.4 mL, P=0.001). PMID:22488490

  12. Hydrodynamics and phases of flocks

    SciTech Connect

    Toner, John; Tu Yuhai . E-mail: yuhai@us.ibm.com; Ramaswamy, Sriram

    2005-07-01

    We review the past decade's theoretical and experimental studies of flocking: the collective, coherent motion of large numbers of self-propelled 'particles' (usually, but not always, living organisms). Like equilibrium condensed matter systems, flocks exhibit distinct 'phases' which can be classified by their symmetries. Indeed, the phases that have been theoretically studied to date each have exactly the same symmetry as some equilibrium phase (e.g., ferromagnets, liquid crystals). This analogy with equilibrium phases of matter continues in that all flocks in the same phase, regardless of their constituents, have the same 'hydrodynamic'-that is, long-length scale and long-time behavior, just as, e.g., all equilibrium fluids are described by the Navier-Stokes equations. Flocks are nonetheless very different from equilibrium systems, due to the intrinsically nonequilibrium self-propulsion of the constituent 'organisms'. This difference between flocks and equilibrium systems is most dramatically manifested in the ability of the simplest phase of a flock, in which all the organisms are, on average moving in the same direction (we call this a 'ferromagnetic' flock; we also use the terms 'vector-ordered' and 'polar-ordered' for this situation) to exist even in two dimensions (i.e., creatures moving on a plane), in defiance of the well-known Mermin-Wagner theorem of equilibrium statistical mechanics, which states that a continuous symmetry (in this case, rotation invariance, or the ability of the flock to fly in any direction) can not be spontaneously broken in a two-dimensional system with only short-ranged interactions. The 'nematic' phase of flocks, in which all the creatures move preferentially, or are simply oriented preferentially, along the same axis, but with equal probability of moving in either direction, also differs dramatically from its equilibrium counterpart (in this case, nematic liquid crystals). Specifically, it shows enormous number fluctuations, which

  13. Calibrating for Ionospheric Phase Delays

    NASA Technical Reports Server (NTRS)

    Macdoran, P. F.

    1985-01-01

    Technique determines ionospheric phase delay on real-time universally applicable basis in terms of electrons per meter squared by coherently modulating two L-band carrier frequencies received from two Global Positioning System satelites. Two pseudorandom number sequences cross-correlated to derive delay time.

  14. New polymers for phase partitioning

    NASA Technical Reports Server (NTRS)

    Harris, J. M.

    1981-01-01

    The synthesizing of several polyethylene glycols having crown ethers attached is reported. This work led to the identification of three new polymer types which promise to be more effective at selectively binding specific cell types. Work was completed on identification of chemical properties of the new polymer crowns and on development of new techniques for determination of polymer-phase composition.

  15. Phase and birefringence aberration correction

    DOEpatents

    Bowers, M.; Hankla, A.

    1996-07-09

    A Brillouin enhanced four wave mixing phase conjugate mirror corrects phase aberrations of a coherent electromagnetic beam and birefringence induced upon that beam. The stimulated Brillouin scattering (SBS) phase conjugation technique is augmented to include Brillouin enhanced four wave mixing (BEFWM). A seed beam is generated by a main oscillator which arrives at the phase conjugate cell before the signal beams in order to initiate the Brillouin effect. The signal beam which is being amplified through the amplifier chain is split into two perpendicularly polarized beams. One of the two beams is chosen to be the same polarization as some component of the seed beam, the other orthogonal to the first. The polarization of the orthogonal beam is then rotated 90{degree} such that it is parallel to the other signal beam. The three beams are then focused into cell containing a medium capable of Brillouin excitation. The two signal beams are focused such that they cross the seed beam path before their respective beam waists in order to achieve BEFWM or the two signal beams are focused to a point or points contained within the focused cone angle of the seed beam to achieve seeded SBS, and thus negate the effects of all birefringent and material aberrations in the system. 5 figs.

  16. Temperature-Stabilized Phase Detector

    NASA Technical Reports Server (NTRS)

    Yeeman, L.

    1985-01-01

    Precise temperature stabilized phase detector for clock signal distribution maintains 100-MHz signal with stability of 5 parts in 10 to the 16th power even for step changes of 20 degrees C in ambient temperature. Stabilization achieved by heating unit to 45 degrees C and maintaining temperature through bridge circuit.

  17. A Truncated Waveguide Phase Shifter

    NASA Technical Reports Server (NTRS)

    Lourie, Nathan P.; Chuss, D. T.; Henry, R.; Wollack, E. J.

    2011-01-01

    The design, fabrication and performance of a simple phase shifter based upon truncated circular and square waveguides is presented. An emphasis is placed upon validation of simple analytical formulae that describe the propagation properties of the structure. A test device is prototyped at approximately 40GHz; however, the concepts explored can be directly extended to millimeter and submillimeter applications.

  18. Phase multiplying electronic scanning array

    NASA Technical Reports Server (NTRS)

    Seaton, A. F.

    1969-01-01

    Scanning array was designed with properties of low RF loss and phase control. The array consists of a series of special waveguides, hybrids made up of two variable reactance branch arms for input signals, an edge slot for the difference port, and a sum arm for the unradiated signal.

  19. Rotor phases in compound semiconductors

    SciTech Connect

    Price, D.L.; Saboungi, M.L.; Howells, W.S.

    1994-11-01

    Quasi-elastic neutron scattering is used to study the disordering processes in two classes of semiconductor: I-IV Zintl compounds and the phosphorus-selenium system. Two alkali-metal-polyvalent metal Zintl compounds, CsPb and NaSn, exhibit a two-stage melting process with high-temperature solid phases characterized by rapid dynamical disorder. In CsPb this disorder is clearly associated with rapid reorientations of polyanions with the cations participating in the dynamical disorder on the same time scale. In NaSn the disorder is associated with fast reorientations of the polyanions closely coupled to a slower migration of the cations. The two high-temperature solid phases of the molecular crystal P{sub 4}Se{sub 3} are confirmed to be rotor phases with small but significant differences in the reorientational motions in the two phases. Zintl compounds are formed from an electropositive metal A and an electronegative metal on semimetal M. Electron transfer from A to M, along with directional bonding between the M-ions, leads to chemical behavior in these ions characteristic of elements to the right of M in the periodic table.

  20. Shock dynamics of phase diagrams

    SciTech Connect

    Moro, Antonio

    2014-04-15

    A thermodynamic phase transition denotes a drastic change of state of a physical system due to a continuous change of thermodynamic variables, as for instance pressure and temperature. The classical van der Waals equation of state is the simplest model that predicts the occurrence of a critical point associated with the gas–liquid phase transition. Nevertheless, below the critical temperature theoretical predictions of the van der Waals theory significantly depart from the observed physical behaviour. We develop a novel approach to classical thermodynamics based on the solution of Maxwell relations for a generalised family of nonlocal entropy functions. This theory provides an exact mathematical description of discontinuities of the order parameter within the phase transition region, it explains the universal form of the equations of state and the occurrence of triple points in terms of the dynamics of nonlinear shock wave fronts. -- Highlights: •A new generalisation of van der Waals equation of state. •Description of phase transitions in terms of shock dynamics of state curves. •Proof of the universality of equations of state for a general class of models. •Interpretation of triple points as confluence of classical shock waves. •Correspondence table between thermodynamics and nonlinear conservation laws.

  1. Phase-Elective English, 1970.

    ERIC Educational Resources Information Center

    Jefferson County Board of Education, Louisville, KY.

    These 40 elective courses, each phased according to one of five levels of difficulty and each comprising 12 weeks of study (a minimum of three courses being required of every student per academic year), offer an individualized program designed to realistically serve the immediate needs and future objectives of each student. Provided for each…

  2. Liquid-Phase Adsorption Fundamentals.

    ERIC Educational Resources Information Center

    Cooney, David O.

    1987-01-01

    Describes an experiment developed and used in the unit operations laboratory course at the University of Wyoming. Involves the liquid-phase adsorption of an organic compound from aqueous solution on activated carbon, and is relevant to adsorption processes in general. (TW)

  3. Phase and birefringence aberration correction

    DOEpatents

    Bowers, Mark; Hankla, Allen

    1996-01-01

    A Brillouin enhanced four wave mixing phase conjugate mirror corrects phase aberrations of a coherent electromagnetic beam and birefringence induced upon that beam. The stimulated Brillouin scattering (SBS) phase conjugation technique is augmented to include Brillouin enhanced four wave mixing (BEFWM). A seed beam is generated by a main oscillator which arrives at the phase conjugate cell before the signal beams in order to initiate the Brillouin effect. The signal beam which is being amplified through the amplifier chain is split into two perpendicularly polarized beams. One of the two beams is chosen to be the same polarization as some component of the seed beam, the other orthogonal to the first. The polarization of the orthogonal beam is then rotated 90.degree. such that it is parallel to the other signal beam. The three beams are then focused into cell containing a medium capable of Brillouin excitation. The two signal beams are focused such that they cross the seed beam path before their respective beam waists in order to achieve BEFWM or the two signal beams are focused to a point or points contained within the focused cone angle of the seed beam to achieve seeded SBS, and thus negate the effects of all birefringent and material aberrations in the system.

  4. Phase 1 Program Joint Report

    NASA Technical Reports Server (NTRS)

    Nield, George C. (Editor); Vorobiev, Pavel Mikhailovich (Editor)

    1999-01-01

    This report consists of inputs from each of the Phase I Program Joint Working Groups. The Working Groups were tasked to describe the organizational structure and work processes that they used during the program, joint accomplishments, lessons learned, and applications to the International Space Station Program. This report is a top-level joint reference document that contains information of interest to both countries.

  5. Circadian phase relationships in monkeys

    NASA Technical Reports Server (NTRS)

    Smith, R. E.; Wekstein, D. R.

    1973-01-01

    Two adult male pigtail monkeys were placed in an isolated, soundproofed chamber (entered for cleaning only) for a period of six months, during which time their deep body temperatures T sub DB, telemetered from transmitters implanted in the abdominal cavity), fluid intake, urinary output (UV), urinary sodium and potassium were continuously monitored. During the first 3 1/2 months, lights (L) were turned on at 0000 hours, off at 1200 hours. Photoperiod phase was then delayed (light span prolonged) 6 hours to a new schedule: L on at 0600 hours, off at 1800 hours. Six weeks later, photoperiod phase was advanced 6 hours to return to the original schedule. Prior to shift, T sub DB typically began a steep rise 0-5 hours prior to L on, a steep fall 3-4 hours prior to L off, relative plateaus in between. Urinary Na typically peaks 2 hours prior to L off, has a minimum 2-4 hours prior to L on; K tends both to peak and show a minimum 2-8 hours earlier than Na; in contrast, UV peaks at L on, has a minimum 2-6 hours after L off. Upon delaying photoperiod phase, T sub DB shift was completed in 8 days. UV shifted more rapidly but tended to overshoot the new phase. Within 5 days, UV and K completed their shifts, although Na did not fully resynchronize within the 6 week period monitored.

  6. Backyard Astronomy: Observing Moon Phases.

    ERIC Educational Resources Information Center

    Brandou, Bob

    1997-01-01

    Presents an activity involving the observation of moon phases that can provide a one-on-one learning experience and stimulate interaction between a child and an adult family member. This activity can also be initiated by teachers and outcomes can be integrated into the classroom science curriculum. (JRH)

  7. Phase Transitions in Dipalmitoylphosphatidylcholine Monolayers.

    PubMed

    Zuo, Yi Y; Chen, Rimei; Wang, Xianju; Yang, Jinlong; Policova, Zdenka; Neumann, A Wilhelm

    2016-08-23

    A self-assembled phospholipid monolayer at an air-water interface is a well-defined model system for studying surface thermodynamics, membrane biophysics, thin-film materials, and colloidal soft matter. Here we report a study of two-dimensional phase transitions in the dipalmitoylphosphatidylcholine (DPPC) monolayer at the air-water interface using a newly developed methodology called constrained drop surfactometry (CDS). CDS is superior to the classical Langmuir balance in its capacity for rigorous temperature control and leak-proof environments, thus making it an ideal alternative to the Langmuir balance for studying lipid polymorphism. In addition, we have developed a novel Langmuir-Blodgett (LB) transfer technique that allows the direct transfer of lipid monolayers from the droplet surface under well-controlled conditions. This LB transfer technique permits the direct visualization of phase coexistence in the DPPC monolayer. With these technological advances, we found that the two-dimensional phase behavior of the DPPC monolayer is analogous to the three-dimensional phase transition of a pure substance. This study has implications in the fundamental understanding of surface thermodynamics as well as applications such as self-assembled monolayers and pulmonary surfactant biophysics. PMID:27479299

  8. Magnetic anisotropy of ferrosmectic phases

    NASA Astrophysics Data System (ADS)

    Ponsinet, Virginie; Fabre, Pascale; Veyssié, Madeleine; Cabanel, Régis

    1994-10-01

    A new anisotropic magnetic fluid, called ferrosmectic, is obtained when using a colloidal suspension of submicronic magnetic particles (ferrofluid), as a component in a smectic phase of fluid membranes. These lamellar phases present specific magnetic properties. The anisotropy of their magnetic susceptilities as a function of particles concentration is studied and interpreted : a microscopic mechanism involving a steric hindrance between particles and membranes is used to understand the experimental results. Un nouveau fluide magnétique anisotrope, appelé ferrosmectique, est obtenu lorsque nous utilisons un ferrofluide, c'est-à-dire une suspension colloïdale de particules magnétiques de taille inférieure au micron, comme composant dans la fabrication d'une phase smectique de membranes fluides. Ces phases adoptent des comportements spécifiques sous champ magnétique, et nous présentons ici une étude de l'anisotropie de leur susceptibilité magnétique en fonction de la concentration en particules. Nous interprétons les résultats obtenus par un mécanisme microscopique basé sur l'existence d'une gêne stérique entre membranes et particules.

  9. Receiver Would Control Phasing of a Phased-Array Antenna

    NASA Technical Reports Server (NTRS)

    Dunn, Charles E.; Young, Lawrence E.

    2006-01-01

    In a proposed digital signal-processing technique, a radio receiver would control the phasing of a phased-array antenna to aim the peaks of the antenna radiation pattern toward desired signal sources while aiming the nulls of the pattern toward interfering signal sources. The technique was conceived for use in a Global Positioning System (GPS) receiver, for which the desired signal sources would be GPS satellites and typical interference sources would be terrestrial objects that cause multipath propagation. The technique could also be used to optimize reception in spread-spectrum cellular-telephone and military communication systems. During reception of radio signals in a conventional phased-array antenna system, received signals at their original carrier frequencies are phase-shifted, then combined by analog circuitry. The combination signal is then subjected to down-conversion and demodulation. In a system according to the proposed technique (see figure), the signal received by each antenna would be subjected to down-conversion, spread-spectrum demodulation, and correlation; this processing would be performed separately from, and simultaneously with, similar processing of signals received by the other antenna elements. Following analog down-conversion to baseband, the signals would be digitized, and all subsequent processing would be digital. In the digital process, residual carriers would be removed and each signal would be correlated with a locally generated model pseudorandum-noise code, all following normal GPS procedure. As part of this procedure, accumulated values would be added in software and the resulting signals would be phase-shifted in software by the amounts necessary to synthesize the desired antenna directional gain pattern of peaks and nulls. The principal advantage of this technique over the conventional radio-frequency-combining technique is that the parallel digital baseband processing of the signals from the various antenna elements would be

  10. Fourier Phase Domain Steganography: Phase Bin Encoding Via Interpolation

    NASA Astrophysics Data System (ADS)

    Rivas, Edward

    2007-04-01

    In recent years there has been an increased interest in audio steganography and watermarking. This is due primarily to two reasons. First, an acute need to improve our national security capabilities in light of terrorist and criminal activity has driven new ideas and experimentation. Secondly, the explosive proliferation of digital media has forced the music industry to rethink how they will protect their intellectual property. Various techniques have been implemented but the phase domain remains a fertile ground for improvement due to the relative robustness to many types of distortion and immunity to the Human Auditory System. A new method for embedding data in the phase domain of the Discrete Fourier Transform of an audio signal is proposed. Focus is given to robustness and low perceptibility, while maintaining a relatively high capacity rate of up to 172 bits/s.

  11. Phase Length Optical Phase-Locked-Loop Sensor

    NASA Technical Reports Server (NTRS)

    Heyman, Joseph S. (Inventor)

    1988-01-01

    The invention is a device that provides a high resolution measurement of the change in optical phase length from the device optical system source to an optical reflector. The invention consists of a optical phase locked loop that uses a laser beam as a carrier of an intensity modulated energy source. The novelty of the invention appears to lie in the overall combination of elements which provide high resolution without loss of wide dynamic range. The invention does not depend on coherent reflection from a target, and thus can measure targets that do not have special preparation or corner reflectors. The use of carrier modulation achieves high resolution without the problems of high speed pulse duration systems. Thus the invention has the advantages of simplicity, low cost, and small size without sacrificing resolution.

  12. Phase Errors and the Capture Effect

    SciTech Connect

    Blair, J., and Machorro, E.

    2011-11-01

    This slide-show presents analysis of spectrograms and the phase error of filtered noise in a signal. When the filtered noise is smaller than the signal amplitude, the phase error can never exceed 90{deg}, so the average phase error over many cycles is zero: this is called the capture effect because the largest signal captures the phase and frequency determination.

  13. Nonclassicality in phase-number uncertainty relations

    SciTech Connect

    Matia-Hernando, Paloma; Luis, Alfredo

    2011-12-15

    We show that there are nonclassical states with lesser joint fluctuations of phase and number than any classical state. This is rather paradoxical since one would expect classical coherent states to be always of minimum uncertainty. The same result is obtained when we replace phase by a phase-dependent field quadrature. Number and phase uncertainties are assessed using variance and Holevo relation.

  14. Three-Phase Power Factor Controller

    NASA Technical Reports Server (NTRS)

    Nola, F. J.

    1982-01-01

    Three-Phase Power-Factor Controller develops a control signal for each motor winding. As motor loading decreases, rms value of applied voltage is decreased by feedback-control circuit. Power consumption is therefore lower than in unregulated operation. Controller employs phase detector for each of three phases of delta-connected induction motor. Phase-difference sum is basis for control.

  15. Condensing, Two-Phase, Contact Heat Exchanger

    NASA Technical Reports Server (NTRS)

    Cox, R. L.; Oren, J. A.; Sauer, L. W.

    1988-01-01

    Two-phase heat exchanger continuously separates liquid and vapor phases of working fluid and positions liquid phase for efficient heat transfer. Designed for zero gravity. Principle is adapted to other phase-separation applications; for example, in thermodynamic cycles for solar-energy conversion.

  16. Simultaneous microemulsion-aqueous phase flooding process

    SciTech Connect

    Reed, R. L.

    1980-12-23

    A method of enhanced oil recovery is disclosed wherein an upper-phase or a middle-phase microemulsion and an immiscible aqueous phase are simultaneously injected into a subterranean formation. The viscosities of the injected phases are adjusted so that the aqueous phase/microemulsion viscosity ratio approximates the reservoir brine/oil viscosity ratio. The injection rates of the injected phases are such that similar oil, microemulsion and aqueous phase velocities are achieved in the reservoir. Oil is displaced to a production well and recovered.

  17. Nanostructures having crystalline and amorphous phases

    SciTech Connect

    Mao, Samuel S; Chen, Xiaobo

    2015-04-28

    The present invention includes a nanostructure, a method of making thereof, and a method of photocatalysis. In one embodiment, the nanostructure includes a crystalline phase and an amorphous phase in contact with the crystalline phase. Each of the crystalline and amorphous phases has at least one dimension on a nanometer scale. In another embodiment, the nanostructure includes a nanoparticle comprising a crystalline phase and an amorphous phase. The amorphous phase is in a selected amount. In another embodiment, the nanostructure includes crystalline titanium dioxide and amorphous titanium dioxide in contact with the crystalline titanium dioxide. Each of the crystalline and amorphous titanium dioxide has at least one dimension on a nanometer scale.

  18. Linear phase distribution of acoustical vortices

    SciTech Connect

    Gao, Lu; Zheng, Haixiang; Ma, Qingyu; Tu, Juan; Zhang, Dong

    2014-07-14

    Linear phase distribution of phase-coded acoustical vortices was theoretically investigated based on the radiation theory of point source, and then confirmed by experimental measurements. With the proposed criterion of positive phase slope, the possibility of constructing linear circular phase distributions is demonstrated to be determined by source parameters. Improved phase linearity can be achieved at larger source number, lower frequency, smaller vortex radius, and/or longer axial distance. Good agreements are observed between numerical simulations and measurement results for circular phase distributions. The favorable results confirm the feasibility of precise phase control for acoustical vortices and suggest potential applications in particle manipulation.

  19. Liquid-phase compositions from vapor-phase analyses

    SciTech Connect

    Davis, W. Jr.; Cochran, H.D.; Leitnaker, J.M.

    1989-09-01

    In the safe handling and processing of uranium hexafluoride (UF{sub 6}), it is often desirable to calculate vapor composition and pressure from known liquid composition and temperature. Furthermore, the ability to use analyses of equilibrium vapor-phase samples to calculate liquid-phase compositions would be economically advantageous to the International Atomic Energy Agency (IAEA) in its international safeguards program and to uranium enrichment operators. The latter technique is projected to save the IAEA on the order of $1500 or more per sample. Either type of calculation could be performed with a multicomponent vapor-liquid equilibrium (VLE) model if this model were shown to apply to UF{sub 6} and its common impurities. This report is concerned with the distribution of four potential impurities in UF{sub 6} between liquid and vapor phases. The impurities are carbon dioxide, sulfur hexafluoride, chloryl fluoride, and Freon-114 (CClF{sub 2}CClF{sub 2}). There are no binary equilibrium data on the first three of these impurities; hence, the VLE calculations are based entirely on the thermodynamic properties of the pure components. There are two sets of binary equilibrium data for the system Freon-114-UF{sub 6} that are analyzed in terms of the model of Prausnitz et al. Calculations based on these data are compared with those based solely on the thermodynamic properties of pure Freon-114 and pure UF{sub 6}. 23 refs., 3 figs., 5 tabs.

  20. Griffiths phase and temporal effects in phase separated manganites

    NASA Astrophysics Data System (ADS)

    Krivoruchko, V. N.; Marchenko, M. A.

    2016-08-01

    Phenomenological description of relaxation phenomena in magnetic and transport properties of perovskite manganites has been presented. The approach is based on generalization of some hypotheses appropriate to the Preisach picture of magnetization process for half-metallic ferromagnets and on an assumption that in doped manganites the phase separated state exists near the magnetic ordering temperature. For systems with the percolation type of a ferromagnet-paramagnet transition, distinctive features in relaxation of magnetization and resistivity have been found. The relaxation is shown to be most pronounced near the transition temperature, and to be an approximately logarithmic function of time. The theoretical results replicate a broad spectrum of behavior observed experimentally on time dependence of magnetization and resistivity of CMR systems and allow a direct comparison with available experimental data. We propose an additional experimental test to distinguish between the percolation scenario of magnetic and transport transitions in doped manganites, and the ferromagnetic polaron picture. In particular, an anomalously slow relaxation to zero of the order parameter can be considered as a key feature of the Griffiths-like phase transition in doped manganites. It is also shown that a system with the Griffiths-like state will exhibit nonequilibrium aging and rejuvenation phenomena, which in many aspects resemble that of a spin glass. We hope that experimental observation of a set of time decay properties will provide a settlement of apparently conflicting results obtained for different characteristics of phase-separated manganites.

  1. Double reference pulsed phase locked loop

    NASA Technical Reports Server (NTRS)

    Heyman, J. S. (Inventor)

    1986-01-01

    A double reference pulse phase locked loop is described which measures the phase shift between tone burst signals initially derived from the same periodic signal source (voltage controlled oscillator) and delayed by different amounts because of two different paths. A first path is from the transducer to the surface of a sample and back. A second path is from the transducer to the opposite surface and back. A first pulse phase locked loop including a phase detector and a phase shifter forces the tone burst signal delayed by the second path in phase quadrature with the periodic signal source. A second pulse phase locked loop including a second phase detector forces the tone burst signals delayed by the first path into phase quadrature with the phase shifted periodic signal source.

  2. Randomized Grain Boundary Liquid Crystal Phase

    NASA Astrophysics Data System (ADS)

    Chen, D.; Wang, H.; Li, M.; Glaser, M.; Maclennan, J.; Clark, N.

    2012-02-01

    The formation of macroscopic, chiral domains, in the B4 and dark conglomerate phases, for example, is a feature of bent-core liquid crystals resulting from the interplay of chirality, molecular bend and molecular tilt. We report a new, chiral phase observed in a hockey stick-like liquid crystal molecule. This phase appears below a smectic A phase and cools to a crystal phase. TEM images of the free surface of the chiral phase show hundreds of randomly oriented smectic blocks several hundred nanometers in size, similar to those seen in the twist grain boundary (TGB) phase. However, in contrast to the TGB phase, these blocks are randomly oriented. The characteristic defects in this phase are revealed by freeze-fracture TEM images. We will show how these defects mediate the randomized orientation and discuss the intrinsic mechanism driving the formation of this phase. This work is supported by NSF MRSEC Grant DMR0820579 and NSF Grant DMR0606528.

  3. Phase-filed modelling and synchrotron validation of phase transformations in martensitic dual-phase steel

    SciTech Connect

    Thiessen, R.G.; Sietsma, J.; Palmer, T.A.; Elmer, J.W.; Richardson, I.M.

    2008-11-12

    A thermodynamically based method to describe the phase transformations during heating and cooling of martensitic dual-phase steel has been developed, and in situ synchrotron measurements of phase transformations have been undertaken to support the model experimentally. Nucleation routines are governed by a novel implementation of the classical nucleation theory in a general phase-field code. Physically-based expressions for the temperature-dependent interface mobility and the driving forces for transformation have also been constructed. Modelling of martensite was accomplished by assuming a carbon supersaturation of the body-centred-cubic ferrite lattice. The simulations predict kinetic aspects of the austenite formation during heating and ferrite formation upon cooling. Simulations of partial austenitising thermal cycles predicted peak and retained austenite percentages of 38.2% and 6.7%, respectively, while measurements yielded peak and retained austenite percentages of 31.0% and 7.2% ({+-}1%). Simulations of a complete austenitisation thermal cycle predicted the measured complete austenitisation and, upon cooling, a retained austenite percentage of 10.3% while 9.8% ({+-}1%) retained austenite was measured.

  4. Nonadditive Mixed State Phases in Neutron Optics

    SciTech Connect

    Klepp, J.; Sponar, S.; Filipp, S.; Lettner, M.; Badurek, G.; Hasegawa, Y.

    2009-03-10

    In a neutron polarimetry experiment mixed neutron spin phases are determined. We consider evolutions leading to purely geometric, purely dynamical and combined phases. It is experimentally demonstrated that the sum of the geometric and dynamical phases--both obtained in separate measurements--is not equal to the associated total phase as obtained from a third measurement, unless the system is in a pure state. In this sense, mixed state phases are not additive.

  5. Phase control system concepts and simulations

    SciTech Connect

    Lindsay, V.C.

    1980-07-01

    A phase control system concept for a solar power satellite is proposed which partitions the system into three major levels. The first level of phase control consists of a reference phase distribution system implemented in the form of phase distribution tree structure. The major purpose of the tree structure is to electronically compensate for the phase shift due to the transition path lengths from the center of the spacetenna to each phase control center located in each subarray. In the reference system, this is accomplished using the master slave returnable timing system technique. The second level of phase control consists of the beam steering and microwave power generating system which houses the power transponders. This transponder consists of a set of phase conjugation multipliers driven by the reference phase distribution system output and the output of a pilot spread spectrum receiver which accepts the received pilot via a diplexer connected to a separate receive horn or the subarray itself. The output of the phase conjugation circuits serve as inputs to the third level of the phase control system. The third level of phase control is associated with maintaining an equal and constant phase shift through the microwave power amplifier devices while minimizing the associated phase noise effects on the generated power beam. This is accomplished by providing a phase locked loop around each high power amplifier.

  6. Quantitative phase imaging of arthropods

    NASA Astrophysics Data System (ADS)

    Sridharan, Shamira; Katz, Aron; Soto-Adames, Felipe; Popescu, Gabriel

    2015-11-01

    Classification of arthropods is performed by characterization of fine features such as setae and cuticles. An unstained whole arthropod specimen mounted on a slide can be preserved for many decades, but is difficult to study since current methods require sample manipulation or tedious image processing. Spatial light interference microscopy (SLIM) is a quantitative phase imaging (QPI) technique that is an add-on module to a commercial phase contrast microscope. We use SLIM to image a whole organism springtail Ceratophysella denticulata mounted on a slide. This is the first time, to our knowledge, that an entire organism has been imaged using QPI. We also demonstrate the ability of SLIM to image fine structures in addition to providing quantitative data that cannot be obtained by traditional bright field microscopy.

  7. Minimally packed phases in holography

    NASA Astrophysics Data System (ADS)

    Donos, Aristomenis; Gauntlett, Jerome P.

    2016-03-01

    We numerically construct asymptotically AdS black brane solutions of D = 4 Einstein-Maxwell theory coupled to a pseudoscalar. The solutions are holographically dual to d = 3 CFTs at finite chemical potential and in a constant magnetic field, which spontaneously break translation invariance leading to the spontaneous formation of abelian and momentum magnetisation currents flowing around the plaquettes of a periodic Bravais lattice. We analyse the three-dimensional moduli space of lattice solutions, which are generically oblique, and show, for a specific value of the magnetic field, that the free energy is minimised by the triangular lattice, associated with minimal packing of circles in the plane. We show that the average stress tensor for the thermodynamically preferred phase is that of a perfect fluid and that this result applies more generally to spontaneously generated periodic phases. The triangular structure persists at low temperatures indicating the existence of novel crystalline ground states.

  8. Phase transformations in engineering materials

    SciTech Connect

    Bourke, M.A.M.; Lawson, A.C.; Dunand, D.C.; Priesmeyer, H.G.

    1996-06-01

    Phase transformations in engineering materials are inevitably related to mechanical behavior and are often precursors to residual stress and distortion. Neutron scattering in general is a valuable tool for studying their effects, and pulsed neutrons are of special value, because of the inherently comprehensive crystallographic coverage they provide in each measurement. At the Manuel Lujan neutron scattering center several different research programs have addressed the relationships between phase transformation/mechanical behavior and residual strains. Three disparate examples are presented; (1) stress induced transformation in a NiTi shape memory alloy, (2) cryogenically induced transformation in a quenched 5180 steel, and (3) time resolved evolution of strain induced martensite in 304 stainless steel. In each case a brief description of the principle result will be discussed in the context of using neutrons for the measurement.

  9. Light-driven phase shifter

    DOEpatents

    Early, James W.

    1990-01-01

    A light-driven phase shifter is provided for modulating a transmission light beam. A gaseous medium such as argon is provided with electron energy states excited to populate a metastable state. A tunable dye laser is selected with a wavelength effective to deplete the metastable electron state and may be intensity modulated. The dye laser is directed through the gaseous medium to define a first optical path having an index of refraction determined by the gaseous medium having a depleted metastable electron state. A transmission laser beam is also directed through the gaseous medium to define a second optical path at least partially coincident with the first optical path. The intensity of the dye laser beam may then be varied to phase modulate the transmission laser beam.

  10. Coherent phase argument for inflation

    SciTech Connect

    Scott Dodelson

    2004-03-17

    Cosmologists have developed a phenomenally successful picture of structure in the universe based on the idea that the universe expanded exponentially in its earliest moments. There are three pieces of evidence for this exponential expansion--inflation--from observations of anisotropies in the cosmic microwave background. First, the shape of the primordial spectrum is very similar to that predicted by generic inflation models. Second, the angular scale at which the first acoustic peak appears is consistent with the flat universe predicted by inflation. Here the author describes the third piece of evidence, perhaps the most convincing of all: the phase coherence needed to account for the clear peak/trough structure observed by the WMAP satellite and its predecessors. The author also discusses alternatives to inflation that have been proposed recently and explain how they produce coherent phases.

  11. Brain Performance versus Phase Transitions

    NASA Astrophysics Data System (ADS)

    Torres, Joaquín J.; Marro, J.

    2015-07-01

    We here illustrate how a well-founded study of the brain may originate in assuming analogies with phase-transition phenomena. Analyzing to what extent a weak signal endures in noisy environments, we identify the underlying mechanisms, and it results a description of how the excitability associated to (non-equilibrium) phase changes and criticality optimizes the processing of the signal. Our setting is a network of integrate-and-fire nodes in which connections are heterogeneous with rapid time-varying intensities mimicking fatigue and potentiation. Emergence then becomes quite robust against wiring topology modification—in fact, we considered from a fully connected network to the Homo sapiens connectome—showing the essential role of synaptic flickering on computations. We also suggest how to experimentally disclose significant changes during actual brain operation.

  12. Liquid Phase Miscibility Gap Materials

    NASA Technical Reports Server (NTRS)

    Gelles, S. H.; Markworth, A. J.

    1985-01-01

    The manner in which the microstructural features of liquid-phase miscibility gap alloys develop was determined. This will allow control of the microstructures and the resultant properties of these alloys. The long-duration low gravity afforded by the shuttle will allow experiments supporting this research to be conducted with minimal interference from buoyancy effects and gravitationally driven convection currents. Ground base studies were conducted on Al-In, Cu-Pb, and Te-Tl alloys to determine the effect of cooling rate, composition, and interfacial energies on the phase separation and solidification processes that influence the development of microstructure in these alloys. Isothermal and directional cooling experiments and simulations are conducted. The ground based activities are used as a technological base from which flight experiments formulated and to which these flight experiments are compared.

  13. Two-phase potential flow

    NASA Technical Reports Server (NTRS)

    Wallis, Graham B.

    1989-01-01

    Some features of two recent approaches of two-phase potential flow are presented. The first approach is based on a set of progressive examples that can be analyzed using common techniques, such as conservation laws, and taken together appear to lead in the direction of a general theory. The second approach is based on variational methods, a classical approach to conservative mechanical systems that has a respectable history of application to single phase flows. This latter approach, exemplified by several recent papers by Geurst, appears generally to be consistent with the former approach, at least in those cases for which it is possible to obtain comparable results. Each approach has a justifiable theoretical base and is self-consistent. Moreover, both approaches appear to give the right prediction for several well-defined situations.

  14. Fiber bundle phase conjugate mirror

    SciTech Connect

    Ward, Benjamin G.

    2012-05-01

    An improved method and apparatus for passively conjugating the phases of a distorted wavefronts resulting from optical phase mismatch between elements of a fiber laser array are disclosed. A method for passively conjugating a distorted wavefront comprises the steps of: multiplexing a plurality of probe fibers and a bundle pump fiber in a fiber bundle array; passing the multiplexed output from the fiber bundle array through a collimating lens and into one portion of a non-linear medium; passing the output from a pump collection fiber through a focusing lens and into another portion of the non-linear medium so that the output from the pump collection fiber mixes with the multiplexed output from the fiber bundle; adjusting one or more degrees of freedom of one or more of the fiber bundle array, the collimating lens, the focusing lens, the non-linear medium, or the pump collection fiber to produce a standing wave in the non-linear medium.

  15. Deep space LADAR, phase 1

    NASA Astrophysics Data System (ADS)

    Frey, Randy W.; Rawlins, Greg; Zepkin, Neil; Bohlin, John

    1989-03-01

    A pseudo-ranging laser radar (PRLADAR) concept is proposed to provide extended range capability to tracking LADAR systems meeting the long-range requirements of SDI mission scenarios such as the SIE midcourse program. The project will investigate the payoff of several transmitter modulation techniques and a feasibility demonstration using a breadboard implementation of a new receiver concept called the Phase Multiplexed Correlator (PMC) will be accomplished. The PRLADAR concept has specific application to spaceborne LADAR tracking missions where increased CNR/SNR performance gained by the proposed technique may reduce the laser power and/or optical aperture requirement for a given mission. The reduction in power/aperture has similar cost reduction advantages in commercial ranging applications. A successful Phase 1 program will lay the groundwork for a quick reaction upgrade to the AMOS/LASE system in support of near term SIE measurement objectives.

  16. Agent review phase one report.

    SciTech Connect

    Zubelewicz, Alex Tadeusz; Davis, Christopher Edward; Bauer, Travis LaDell

    2009-12-01

    This report summarizes the findings for phase one of the agent review and discusses the review methods and results. The phase one review identified a short list of agent systems that would prove most useful in the service architecture of an information management, analysis, and retrieval system. Reviewers evaluated open-source and commercial multi-agent systems and scored them based upon viability, uniqueness, ease of development, ease of deployment, and ease of integration with other products. Based on these criteria, reviewers identified the ten most appropriate systems. The report also mentions several systems that reviewers deemed noteworthy for the ideas they implement, even if those systems are not the best choices for information management purposes.

  17. Quantitative phase imaging of arthropods

    PubMed Central

    Sridharan, Shamira; Katz, Aron; Soto-Adames, Felipe; Popescu, Gabriel

    2015-01-01

    Abstract. Classification of arthropods is performed by characterization of fine features such as setae and cuticles. An unstained whole arthropod specimen mounted on a slide can be preserved for many decades, but is difficult to study since current methods require sample manipulation or tedious image processing. Spatial light interference microscopy (SLIM) is a quantitative phase imaging (QPI) technique that is an add-on module to a commercial phase contrast microscope. We use SLIM to image a whole organism springtail Ceratophysella denticulata mounted on a slide. This is the first time, to our knowledge, that an entire organism has been imaged using QPI. We also demonstrate the ability of SLIM to image fine structures in addition to providing quantitative data that cannot be obtained by traditional bright field microscopy. PMID:26334858

  18. Phase comparator apparatus and method

    DOEpatents

    Coffield, F.E.

    1985-02-01

    This invention finds especially useful application for interferometer measurements made in plasma fusion devices (e.g., for measuring the line integral of electron density in the plasma). Such interferometers typically use very high intermediate frequencies (e.g., on the order of 10 to 70 MHz) and therefore the phase comparison circuitry should be a high speed circuit with a linear transfer characteristic so as to accurately differentiate between small fractions of interference fringes.

  19. Final Report: Sensorpedia Phase 3

    SciTech Connect

    Gorman, Bryan L; Resseguie, David R

    2011-02-01

    This report is a summary of the Oak Ridge National Laboratory s (ORNL s) Phase 3 development of Sensorpedia, a sensor information sharing platform. Sensorpedia is ORNL s Wikipedia for Sensors. The overall goal of Sensorpedia is to enable global scale sensor information sharing for scientific research, national security and defense, public health and safety, emergency preparedness and response, and general community awareness and outreach.

  20. Disposal phase experimental program plan

    SciTech Connect

    1997-01-31

    The Waste Isolation Pilot Plant (WIPP) facility comprises surface and subsurface facilities, including a repository mined in a bedded salt formation at a depth of 2,150 feet. It has been developed to safely and permanently isolate transuranic (TRU) radioactive wastes in a deep geological disposal site. On April 12, 1996, the DOE submitted a revised Resource Conservation and Recovery Act (RCRA) Part B permit application to the New Mexico Environment Department (NMED). The DOE anticipates receiving an operating permit from the NMED; this permit is required prior to the start of disposal operations. On October 29, 1996, the DOE submitted a Compliance Certification Application (CCA) to the US Environmental Protection Agency (EPA) in accordance with the WIPP land Withdrawal Act (LWA) of 1992 (Public Law 102-579) as amended, and the requirements of Title 40 of the Code of Federal Regulations (40 CFR) Parts 191 and 194. The DOE plans to begin disposal operations at the WIPP in November 1997 following receipt of certification by the EPA. The disposal phase is expected to last for 35 years, and will include recertification activities no less than once every five years. This Disposal Phase Experimental Program (DPEP) Plan outlines the experimental program to be conducted during the first 5-year recertification period. It also forms the basis for longer-term activities to be carried out throughout the 35-year disposal phase. Once the WIPP has been shown to be in compliance with regulatory requirements, the disposal phase gives an opportunity to affirm the compliance status of the WIPP, enhance the operations of the WIPP and the national TRU system, and contribute to the resolution of national and international nuclear waste management technical needs. The WIPP is the first facility of its kind in the world. As such, it provides a unique opportunity to advance the technical state of the art for permanent disposal of long-lived radioactive wastes.

  1. Improved Phase-Lock Detector

    NASA Technical Reports Server (NTRS)

    Bronstein, L. M.

    1982-01-01

    Single detection channel is used alternately by in-phase (I) and quadrature (Q) signals, under control of a dither switch. By eliminating errors caused by unbalance of the I and Q channels, this dither-balanced detector reduces false locking. Can be used to improve detection probability and reduce false alarm probability for any loop that must acquire signal with low signal-to-noise ratio.

  2. Multicolor Holography With Phase Shifting

    NASA Technical Reports Server (NTRS)

    Vikram, Chandra S.

    1996-01-01

    Prototype apparatus constructed to test feasibility of two-color holographic interferometric scheme in which data for reconstructing holographic wavefront obtained with help of phase-shifting technique. Provides two sets of data needed to solve equations for effects of temperature and concentration. Concept extended to holography at three or more wavelengths to measure three or more phenomena associated with significant variations in index of refraction

  3. TDRSS telecommunications study, phase 2

    NASA Technical Reports Server (NTRS)

    Cahn, C. R.

    1974-01-01

    Providing an extension to parametric analysis of the telecommunications support capability of the Tracking and Data Relay Satellite System (TDRSS), this phase considers candidate modulation waveforms which could meet the shuttle telecommunications requirements and also be compatible with the TDRSS single access S-band service. In addition, it considers the feasibility of modifying a single access S-band user transponder for operation with conventional STDN signals emanating from remotely located ground stations.

  4. Solid Phase Micro Extraction (SPME)

    NASA Technical Reports Server (NTRS)

    1998-01-01

    Internation Flavors and Fragrances Inc. proprietary research technology, Solid Phase Micro Extraction (SPME) utilizes a special fiber needle placed directly next to the bloom of the living flower to collect the fragrance molecules. SPME was used in the Space Flower experiment aboard STS-95 space shuttle mission, after which Dr. Braja Mookherjee (left) and Subha Patel of IFF will analyze the effects of gravity on the Overnight Scentsation rose plant.

  5. Cabling design for phased arrays

    NASA Technical Reports Server (NTRS)

    Kruger, I. D.; Turkiewicz, L.

    1972-01-01

    The ribbon-cabling system used for the AEGIS phased array which provides minimum cable bulk, complete EMI shielding, rugged mechanical design, repeatable electrical characteristics, and ease of assembly and maintenance is described. The ribbon cables are 0.040-inch thick, and in widths up to 2 1/2 inches. Their terminations are molded connectors that can be grouped in a three-tier arrangement, with cable branching accomplished by a matrix-welding technique.

  6. Phase-preserved optical elevator

    PubMed Central

    Luo, Yuan; Zhang, Baile; Han, Tiancheng; Chen, Zhi; Duan, Yubo; Chu, Chia-Wei; Barbastathis, George; Qiu, Cheng Wei

    2013-01-01

    The unique superiority of transformation optics devices designed from coordinate transformation is their capability of recovering both ray trajectory and optical path length in light manipulation. However, very few experiments have been done so far to verify this dual-recovery property from viewpoints of both ray trajectory and optical path length simultaneously. The experimental difficulties arise from the fact that most previous optical transformation optics devices only work at the nano-scale; the lack of intercomparison between data from both optical path length and ray trajectory measurement in these experiments obscured the fact that the ray path was subject to a subwavelength lateral shift that was otherwise not easily perceivable and, instead, was pointed out theoretically [B. Zhang et al. Phys. Rev. Lett. 104, 233903, (2010)]. Here, we use a simple macroscopic transformation optics device of phase-preserved optical elevator, which is a typical birefringent optical phenomenon that can virtually lift an optical image by a macroscopic distance, to demonstrate decisively the unique optical path length preservation property of transformation optics. The recovery of ray trajectory is first determined with no lateral shift in the reflected ray. The phase preservation is then verified with incoherent white-light interferometry without ambiguity and phase unwrapping. PMID:23546046

  7. Phase Curves of Eccentric Exoplanets

    NASA Astrophysics Data System (ADS)

    Lewis, Nikole K.; de Wit, Julien; Laughlin, Gregory P.; Knutson, Heather

    2016-01-01

    Nearly 15% of the known exoplanet population have significantly eccentric orbits (e > 0.25). Systems with planets on highly eccentric orbits provide natural laboratories to test theories of orbital evolution, tidal forcing, and atmospheric response. The two best studied eccentric exoplanets are HAT-P-2b (e~0.5) and HD 80606 b (e~0.9). Both of these eccentric planets have full or partial orbit phase curve observations taken with the 3.6, 4.5, and 8.0 micron channels of the Spitzer IRAC instrument. These phase-curve observations of HAT-P-2b and HD 80606 b have given us important insights into atmospheric radiative timescales, planetary rotation rates and orbital evolution, and planet-star tidal interactions. Here I will overview the key results from the Spitzer observational campaigns for HAT-P-2b and HD 80606 b and look toward the future of phase curve observations of eccentric exoplanets in the era of JWST.

  8. QCD Phase Transitions, Volume 15

    SciTech Connect

    Schaefer, T.; Shuryak, E.

    1999-03-20

    The title of the workshop, ''The QCD Phase Transitions'', in fact happened to be too narrow for its real contents. It would be more accurate to say that it was devoted to different phases of QCD and QCD-related gauge theories, with strong emphasis on discussion of the underlying non-perturbative mechanisms which manifest themselves as all those phases. Before we go to specifics, let us emphasize one important aspect of the present status of non-perturbative Quantum Field Theory in general. It remains true that its studies do not get attention proportional to the intellectual challenge they deserve, and that the theorists working on it remain very fragmented. The efforts to create Theory of Everything including Quantum Gravity have attracted the lion share of attention and young talent. Nevertheless, in the last few years there was also a tremendous progress and even some shift of attention toward emphasis on the unity of non-perturbative phenomena. For example, we have seen some efforts to connect the lessons from recent progress in Supersymmetric theories with that in QCD, as derived from phenomenology and lattice. Another example is Maldacena conjecture and related development, which connect three things together, string theory, super-gravity and the (N=4) supersymmetric gauge theory. Although the progress mentioned is remarkable by itself, if we would listen to each other more we may have chance to strengthen the field and reach better understanding of the spectacular non-perturbative physics.

  9. Non-equilibrium phase transitions

    SciTech Connect

    Mottola, E.; Cooper, F.M.; Bishop, A.R.; Habib, S.; Kluger, Y.; Jensen, N.G.

    1998-12-31

    This is the final report of a one-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). Non-equilibrium phase transitions play a central role in a very broad range of scientific areas, ranging from nuclear, particle, and astrophysics to condensed matter physics and the material and biological sciences. The aim of this project was to explore the path to a deeper and more fundamental understanding of the common physical principles underlying the complex real time dynamics of phase transitions. The main emphasis was on the development of general theoretical tools to deal with non-equilibrium processes, and of numerical methods robust enough to capture the time-evolving structures that occur in actual experimental situations. Specific applications to Laboratory multidivisional efforts in relativistic heavy-ion physics (transition to a new phase of nuclear matter consisting of a quark-gluon plasma) and layered high-temperature superconductors (critical currents and flux flow at the National High Magnetic Field Laboratory) were undertaken.

  10. Phase change material storage heater

    DOEpatents

    Goswami, D. Yogi; Hsieh, Chung K.; Jotshi, Chand K.; Klausner, James F.

    1997-01-01

    A storage heater for storing heat and for heating a fluid, such as water, has an enclosure defining a chamber therein. The chamber has a lower portion and an upper portion with a heating element being disposed within the enclosure. A tube through which the fluid flows has an inlet and an outlet, both being disposed outside of the enclosure, and has a portion interconnecting the inlet and the outlet that passes through the enclosure. A densely packed bed of phase change material pellets is disposed within the enclosure and is surrounded by a viscous liquid, such as propylene glycol. The viscous liquid is in thermal communication with the heating element, the phase change material pellets, and the tube and transfers heat from the heating element to the pellets and from the pellets to the tube. The viscous fluid has a viscosity so that the frictional pressure drop of the fluid in contact with the phase change material pellets substantially reduces vertical thermal convection in the fluid. As the fluid flows through the tube heat is transferred from the viscous liquid to the fluid flowing through the tube, thereby heating the fluid.

  11. Symmetry in finite phase plane

    NASA Astrophysics Data System (ADS)

    Zak, J.

    2010-03-01

    The known symmetries in one-dimensional systems are inversion and translations. These symmetries persist in finite phase plane, but a novel symmetry arises in view of the discrete nature of the coordinate xi and the momentum pi : xi and pi can undergo permutations. Thus, if xi assumes M discrete values, i = 0, 1,2,..., M - 1, a permutation will change the order of the set x0,x1,..., xM-1 into a new ordered set. Such a symmetry element does not exist for a continuous x-coordinate in an infinite phase plane. Thus, in a finite phase plane, translations can be replaced by permutations. This is also true for the inversion operator. The new permutation symmetry has been used for the construction of conjugate representations and for the splitting of the M-dimensional vector space into independent subspaces. This splitting is exhaustive in the sense that if M = iMi with Mi being prime numbers, the M-dimensional space splits into M1,M2,...Mn-dimensional independent subspaces. It is shown that following this splitting one can design new potentials with appropriate constants of motion. A related problem is the Weyl-Heisenberg group in the M-dimensional space which turns into a direct product of its subgroups in the Mi-dimensional subspaces. As an example we consider the case of M = 8.

  12. Phase diagram of ammonium nitrate

    SciTech Connect

    Dunuwille, Mihindra; Yoo, Choong-Shik

    2013-12-07

    Ammonium Nitrate (AN) is a fertilizer, yet becomes an explosive upon a small addition of chemical impurities. The origin of enhanced chemical sensitivity in impure AN (or AN mixtures) is not well understood, posing significant safety issues in using AN even today. To remedy the situation, we have carried out an extensive study to investigate the phase stability of AN and its mixtures with hexane (ANFO–AN mixed with fuel oil) and Aluminum (Ammonal) at high pressures and temperatures, using diamond anvil cells (DAC) and micro-Raman spectroscopy. The results indicate that pure AN decomposes to N{sub 2}, N{sub 2}O, and H{sub 2}O at the onset of the melt, whereas the mixtures, ANFO and Ammonal, decompose at substantially lower temperatures. The present results also confirm the recently proposed phase IV-IV{sup ′} transition above 17 GPa and provide new constraints for the melting and phase diagram of AN to 40 GPa and 400°C.

  13. Phase Diagram of Ammonium Nitrate

    NASA Astrophysics Data System (ADS)

    Dunuwille, Mihindra; Yoo, Choong-Shik

    2013-06-01

    Ammonium Nitrate (AN) has often been subjected to uses in improvised explosive devices, due to its wide availability as a fertilizer and its capability of becoming explosive with slight additions of organic and inorganic compounds. Yet, the origin of enhanced energetic properties of impure AN (or AN mixtures) is neither chemically unique nor well understood - resulting in rather catastrophic disasters in the past1 and thereby a significant burden on safety, in using ammonium nitrates even today. To remedy this situation, we have carried out an extensive study to investigate the phase stability of AN, in different chemical environments, at high pressure and temperature, using diamond anvil cells and micro-Raman spectroscopy. The present results confirm the recently proposed phase IV-to-IV' transition above 15 GPa2 and provide new constraints for the melting and phase diagram of AN to 40 GPa and 673 K. The present study has been supported by the U.S. DHS under Award Number 2008-ST-061-ED0001.

  14. Metastable Phases in Ice Clouds

    NASA Astrophysics Data System (ADS)

    Weiss, Fabian; Baloh, Philipp; Kubel, Frank; Hoelzel, Markus; Parker, Stewart; Grothe, Hinrich

    2014-05-01

    Polar Stratospheric Clouds and Cirrus Clouds contain both, pure water ice and phases of nitric acid hydrates. Preferentially for the latter, the thermodynamically stable phases have intensively been investigated in the past (e.g. nitric acid trihydrate, beta-NAT). As shown by Peter et al. [1] the water activity inside clouds is higher than expected, which might be explained by the presence of metastable stable phases (e.g. cubic ice). However, also metastable nitric acid hydrates might be important due to the inherent non-equilibrium freezing conditions in the upper atmosphere. The delta ice theory of Gao et al. [2] presents a model approach to solve this problem by involving both metastable ice and NAT as well. So it is of high interest to investigate the metastable phase of NAT (i.e. alpha-NAT), the structure of which was unknown up to the presence. In our laboratory a production procedure for metastable alpha-NAT has been developed, which gives access to neutron diffraction and X-ray diffraction measurements, where sample quantities of several Gramm are required. The diffraction techniques were used to solve the unknown crystalline structure of metastable alpha-NAT, which in turn allows the calculation of the vibrational spectra, which have also been recorded by us in the past. Rerefences [1] Peter, T., C. Marcolli, P. Spichtinger, T. Corti, M. B. Baker, and T. Koop. When dry air is too humid. Science, 314:1399-1402, 2006. [2] Gao, R., P. Popp, D. Fahey, T. Marcy, R. L. Herman, E. Weinstock, D. Baumgardener, T. Garrett, K. Rosenlof, T. Thompson, T. P. Bui, B. Ridley, S. C. Wofsy, O. B. Toon, M. Tolbert, B. Kärcher, Th. Peter, P. K. Hudson, A. Weinheimer, and A. Heymsfield. Evidence That Nitric Acid Increases Relative Humidity in Low-Temperature Cirrus Clouds, Science, 303:516-520, 2004. [3] Tizek, H., E. Knözinger, and H. Grothe. Formation and phase distribution of nitric acid hydrates in the mole fraction range xHNO3<0.25: A combined XRD and IR study, PCCP, 6

  15. Three Phase Primary Science. Phase Three Evaluation. Interim Report. Research Report No. 24.

    ERIC Educational Resources Information Center

    Wilson, Michael

    This evaluation report is concerned with Phase 3 of the Three Phase Primary Science (TPPS) course piloted in Papua, New Guinea, primary schools in 1969 and which was to be taught in all primary schools in 1973. Phase 1 is a series of activities; Phase 2, a series of simple experiments for the pupils. Phase 3 is a series of more formal experiments…

  16. 40 CFR 73.10 - Initial allocations for phase I and phase II.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 17 2012-07-01 2012-07-01 false Initial allocations for phase I and phase II. 73.10 Section 73.10 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) SULFUR DIOXIDE ALLOWANCE SYSTEM Allowance Allocations § 73.10 Initial allocations for phase I and phase II. (a) Phase...

  17. Quantum phases and dynamics of geometric phase in a quantum spin chain under linear quench

    NASA Astrophysics Data System (ADS)

    Sarkar, S.; Basu, B.

    2012-12-01

    We study the quantum phases of anisotropic XY spin chain in presence and absence of adiabatic quench. A connection between geometric phase and criticality is established from the dynamical behavior of the geometric phase for a quench induced quantum phase transition in a quantum spin chain. We predict XX criticality associated with a sequence of non-contractible geometric phases.

  18. Pressure-induced phase transition in pentacene

    NASA Astrophysics Data System (ADS)

    Farina, L.; Brillante, A.; Della Valle, R. G.; Venuti, E.; Amboage, M.; Syassen, K.

    2003-07-01

    We have recently studied two solid phases of bulk pentacene (polymorphs H and C) by means of lattice phonon Raman spectroscopy. The assignment, previously based on lattice dynamics calculations alone, is now verified by X-ray diffraction measurements, conclusively confirming the existence of both polymorphs. Furthermore, Raman phonon spectra indicate a pressure-induced phase transition where the polymorph C (lower density phase) transforms to the H form (higher density phase). The onset pressure for the phase transition is only 0.2 GPa. The phase change is irreversible.

  19. Ponderomotive phase plate for transmission electron microscopes

    DOEpatents

    Reed, Bryan W.

    2012-07-10

    A ponderomotive phase plate system and method for controllably producing highly tunable phase contrast transfer functions in a transmission electron microscope (TEM) for high resolution and biological phase contrast imaging. The system and method includes a laser source and a beam transport system to produce a focused laser crossover as a phase plate, so that a ponderomotive potential of the focused laser crossover produces a scattering-angle-dependent phase shift in the electrons of the post-sample electron beam corresponding to a desired phase contrast transfer function.

  20. Analysis of cardiac fibrillation using phase mapping.

    PubMed

    Clayton, Richard H; Nash, Martyn P

    2015-03-01

    The sequence of myocardial electrical activation during fibrillation is complex and changes with each cycle. Phase analysis represents the electrical activation-recovery process as an angle. Lines of equal phase converge at a phase singularity at the center of rotation of a reentrant wave, and the identification of reentry and tracking of reentrant wavefronts can be automated. We examine the basic ideas behind phase analysis. With the exciting prospect of using phase analysis of atrial electrograms to guide ablation in the human heart, we highlight several recent developments in preprocessing electrograms so that phase can be estimated reliably. PMID:25784022

  1. Two-phase flow research. Phase I. Two-phase nozzle research. Final report

    SciTech Connect

    Toner, S.J.

    1981-07-01

    An investigation of energy transfer in two-phase nozzles was conducted. Experimental performance of converging-diverging nozzles operating on air-water mixtures is presented for a wide range of parameters. Thrust measurements characterized the performance and photographic documentation was used to visually observe the off-design regimes. Thirty-six nozzle configurations were tested to determine the effects of convergence angle, area ratio, and nozzle length. In addition, the pressure ratio and mass flowrate ratio were varied to experimentally map off-design performance. The test results indicate the effects of wall friction and infer temperature and velocity differences between phases and the effect on nozzle performance. The major conclusions reached were: the slip ratio between the phases, gas velocity to liquid velocity, is shown to be below about 4 or 5, and, in most of the test cases run, was estimated to between about 1-1/2 to 2-1/2; in all cases except the free-jet the mass )

  2. Phase diagrams for the blue phases of highly chiral liquid crystals

    NASA Astrophysics Data System (ADS)

    Bowling, Miriam B.; Collings, Peter J.; Booth, Christopher J.; Goodby, John W.

    1993-11-01

    Polarizing microscopy and optical-activity measurements are used to determine the phase diagram for the blue phases of chiral-racemic mixtures of terephthaloyloxy-bis-4-(2'-methylbutyl) benzoate. Contrary to an earlier report, it is the second blue phase (BP II) rather than the first blue phase (BP I) that is not stable relative to the other blue phases at high chirality. With this development, all phase diagrams for the blue phases reported to date have the same topology. Using similar data for two other highly chiral systems, it is found that a simple scaling of the temperature and chiral-fraction axes produces phase diagrams in quantitative agreement with the present results. Thus, in spite of differences in molecular structure, the number of chiral centers, and phase-transition temperatures, these three systems possess remarkably similar phase diagrams and lend evidence for a universal phase diagram for the blue phases.

  3. Simulation of Anti-Galloping Effects of Phase-to-Phase Spacers in Transmission Line

    NASA Astrophysics Data System (ADS)

    Liu, Chao-Qun; Chen, Hua-Ling; Liu, Bin; Liu, Cao-Lan; Sun, Na; Yang, Jia-Lun

    Currently, the application of phase-to-phase spacers can effectively prevent and control line faults caused by conductor galloping and is one of the most effective methods to prevent galloping of transmission lines. The installation layout scheme of phase-to-phase spacers directly affects the anti-galloping effect. Moreover, the common empirical formula can not accurately assess the anti-galloping effect of phase-to-phase spacers. In this paper, the nonlinear finite element method is employed to establish an accurate analysis model of phase-to-phase spacers for conductors. And the anti-galloping effects of phase-to-phase spacers installed in different ways are analyzed, with the aim of providing an effective method for the installation of phase-to-phase spacers used in practical transmission lines.

  4. Unified framework of topological phases with symmetry

    NASA Astrophysics Data System (ADS)

    Gu, Yuxiang; Hung, Ling-Yan; Wan, Yidun

    2014-12-01

    In topological phases in 2 +1 dimensions, anyons fall into representations of quantum group symmetries. As proposed in our work [Hung and Wan, Int. J. Mod. Phys. B 28, 1450172 (2014), 10.1142/S0217979214501720], the physics of a symmetry enriched phase can be extracted by the mathematics of (hidden) quantum group symmetry breaking of a "parent phase." This offers a unified framework and classification of the symmetry enriched (topological) phases, including symmetry protected trivial phases as well. In this paper, we extend our investigation to the case where the "parent" phases are non-Abelian topological phases. We show explicitly how one can obtain the topological data and symmetry transformations of the symmetry enriched phases from that of the "parent" non-Abelian phase. Two examples are computed: (1) the Ising×Ising¯ phase breaks into the Z2 toric code with Z2 global symmetry; (2) the SU (2) 8 phase breaks into the chiral Fibonacci × Fibonacci phase with a Z2 symmetry, a first non-Abelian example of symmetry enriched topological phase beyond the gauge-theory construction.

  5. A novel phase shifting structured illumination microscopy

    NASA Astrophysics Data System (ADS)

    Singh, Veena; Dubey, Vishesh; Ahmad, Azeem; Singh, Gyanendra; Mehta, D. S.

    2016-03-01

    This paper describes a new and novel phase shifting technique for qualitative as well as quantitative measurement in microscopy. We have developed a phase shifting device which is robust, inexpensive and involves no mechanical movement. In this method, phase shifting is implemented using LED array, beam splitters and defocused projection of Ronchi grating. The light from the LEDs are made incident on the beam splitters at spatially different locations. Due to variation in the geometrical distances of LEDs from the Ronchi grating and by sequentially illuminating the grating by switching on one LED at a time the phase shifted grating patterns are generated. The phase shifted structured patterns are projected onto the sample using microscopic objective lens. The phase shifted deformed patterns are recorded by a CCD camera. The initial alignment of the setup involves a simple procedure for the calibration for equal fringe width and intensity such that the phase shifted fringes are at equal phase difference. Three frame phase shifting algorithm is employed for the reconstruction of the phase map. The method described here is fully automated so that the phase shifted images are recorded just by switching of LEDs and has been used for the shape measurement of microscopic industrial objects. The analysis of the phase shifted images provides qualitative as well as quantitative information about the sample. Thus, the method is simple, robust and low cost compared to PZT devices commonly employed for phase shifting.

  6. Nonequilibrium dynamics of phase transitions

    NASA Astrophysics Data System (ADS)

    Gagne, Carmen Jeanne

    2001-11-01

    Phase transitions occur in such diverse and important systems as ferromagnets, liquid crystals and the early Universe. The dynamics of phase transitions such as these have been studied for decades, but the analytical models still need a great deal of improvement before they can adequately describe all time stages and regions under the coexistence curve. Numerical studies can supplement these analytical theories, but they need to accurately describe the continuum equations that they are intended to solve. This thesis describes a method for removing the lattice- spacing and renormalization-mass dependence of Langevin simulations of phase mixing in (2 + 1)-dimensional asymmetric Ginzburg-Landau models with short-ranged interactions. Also, the spread in the order parameter near the critical value of the control parameter due to critical slowing down is used to more accurately determine this value of the control parameter in these simulations. In addition, a new method is proposed for quantifying the departure from equilibrium. The method explores the behavior of the rate of change of the momentum-integrated structure function, ΔStot( t), as it evolves in time. As an illustration, we examine a (1 + 1)-dimensional model of a stochastic Ginzburg-Landau model at varying cooling rates. We show that ΔStot(t) displays a peak which scales with cooling time-scale as t1/2q in the over-damped limit and t1/3q in the underdamped limit. The peak amplitude was found to scale with cooling time-scale as t6/5q in all viscosities studied.

  7. Phase 1 research program overview

    NASA Technical Reports Server (NTRS)

    Uri, J. J.; Lebedev, O. N.

    2001-01-01

    The Phase 1 research program was unprecedented in its scope and ambitious in its objectives. The National Aeronautics and Space Administration committed to conducting a multidisciplinary long-duration research program on a platform whose capabilities were not well known, not to mention belonging to another country. For the United States, it provided the first opportunity to conduct research in a long-duration space flight environment since the Skylab program in the 1970's. Multiple technical as well as cultural challenges were successfully overcome through the dedicated efforts of a relatively small cadre of individuals. The program developed processes to successfully plan, train for and execute research in a long-duration environment, with significant differences identified from short-duration space flight science operations. Between August 1994 and June 1998, thousands of kilograms of research hardware was prepared and launched to Mir, and thousands of kilograms of hardware and data products were returned to Earth. More than 150 Principal Investigators from eight countries were involved in the program in seven major research disciplines: Advanced Technology; Earth Sciences; Fundamental Biology; Human Life Sciences; International Space Station Risk Mitigation; Microgravity; and Space Sciences. Approximately 75 long-duration investigations were completed on Mir, with additional investigations performed on the Shuttle flights that docked with Mir. The flight phase included the participation of seven US astronauts and 20 Russian cosmonauts. The successful completion of the Phase 1 research program not only resulted in high quality science return but also in numerous lessons learned to make the ISS experience more productive. The cooperation developed during the program was instrumental in its success. c2001 AIAA. Published by Elsevier Science Ltd.

  8. Phase 1 research program overview.

    PubMed

    Uri, J J; Lebedev, O N

    2001-01-01

    The Phase 1 research program was unprecedented in its scope and ambitious in its objectives. The National Aeronautics and Space Administration committed to conducting a multidisciplinary long-duration research program on a platform whose capabilities were not well known, not to mention belonging to another country. For the United States, it provided the first opportunity to conduct research in a long-duration space flight environment since the Skylab program in the 1970's. Multiple technical as well as cultural challenges were successfully overcome through the dedicated efforts of a relatively small cadre of individuals. The program developed processes to successfully plan, train for and execute research in a long-duration environment, with significant differences identified from short-duration space flight science operations. Between August 1994 and June 1998, thousands of kilograms of research hardware was prepared and launched to Mir, and thousands of kilograms of hardware and data products were returned to Earth. More than 150 Principal Investigators from eight countries were involved in the program in seven major research disciplines: Advanced Technology; Earth Sciences; Fundamental Biology; Human Life Sciences; International Space Station Risk Mitigation; Microgravity; and Space Sciences. Approximately 75 long-duration investigations were completed on Mir, with additional investigations performed on the Shuttle flights that docked with Mir. The flight phase included the participation of seven US astronauts and 20 Russian cosmonauts. The successful completion of the Phase 1 research program not only resulted in high quality science return but also in numerous lessons learned to make the ISS experience more productive. The cooperation developed during the program was instrumental in its success. PMID:11858276

  9. Imaging phased telescope array study

    NASA Technical Reports Server (NTRS)

    Harvey, James E.

    1989-01-01

    The problems encountered in obtaining a wide field-of-view with large, space-based direct imaging phased telescope arrays were considered. After defining some of the critical systems issues, previous relevant work in the literature was reviewed and summarized. An extensive list was made of potential error sources and the error sources were categorized in the form of an error budget tree including optical design errors, optical fabrication errors, assembly and alignment errors, and environmental errors. After choosing a top level image quality requirment as a goal, a preliminary tops-down error budget allocation was performed; then, based upon engineering experience, detailed analysis, or data from the literature, a bottoms-up error budget reallocation was performed in an attempt to achieve an equitable distribution of difficulty in satisfying the various allocations. This exercise provided a realistic allocation for residual off-axis optical design errors in the presence of state-of-the-art optical fabrication and alignment errors. Three different computational techniques were developed for computing the image degradation of phased telescope arrays due to aberrations of the individual telescopes. Parametric studies and sensitivity analyses were then performed for a variety of subaperture configurations and telescope design parameters in an attempt to determine how the off-axis performance of a phased telescope array varies as the telescopes are scaled up in size. The Air Force Weapons Laboratory (AFWL) multipurpose telescope testbed (MMTT) configuration was analyzed in detail with regard to image degradation due to field curvature and distortion of the individual telescopes as they are scaled up in size.

  10. Phase 1 research program overview

    NASA Astrophysics Data System (ADS)

    Uri, JohnJ.; Lebedev, OlegN.

    2001-03-01

    The Phase 1 research program was unprecedented in its scope and ambitious in its objectives. The National Aeronautics and Space Administration committed to conducting a multidisciplinary long-duration research program on a platform whose capabilities were not well known, not to mention belonging to another country. For the United States, it provided the first opportunity to conduct research in a long-duration space flight environment since the Skylab program in the 1970's. Multiple technical as well as cultural challenges were successfully overcome through the dedicated efforts of a relatively small cadre of individuals. The program developed processes to successfully plan, train for and execute research in a long-duration environment, with significant differences identified from short-duration space flight science operations. Between August 1994 and June 1998, thousands of kilograms of research hardware was prepared and launched to Mir, and thousands of kilograms of hardware and data products were returned to Earth. More than 150 Principal Investigators from eight countries were involved in the program in seven major research disciplines: Advanced Technology; Earth Sciences; Fundamental Biology; Human Life Sciences; International Space Station Risk Mitigation; Microgravity; and Space Sciences. Approximately 75 long-duration investigations were completed on Mir, with additional investigations performed on the Shuttle flights that docked with Mir. The flight phase included the participation of seven US astronauts and 20 Russian cosmonauts. The successful completion of the Phase 1 research program not only resulted in high quality science return but also in numerous lessons learned to make the ISS experience more productive. The cooperation developed during the program was instrumental in its success.

  11. Classical analog of quantum phase

    SciTech Connect

    Ord, G.N.

    1992-07-01

    A modified version of the Feynman relativistic chessboard model (FCM) is investigated in which the paths involved are spirals in the space-time. Portions of the paths in which the particle`s proper time is reversed are interpreted in terms of antiparticles. With this intepretation the particle-antiparticle field produced by such trajectories provides a classical analog of the phase associated with particle paths in the unmodified FCM. It is shwon that in the nonrelativistic limit the resulting kernel is the correct Dirac propagator and that particle-antiparticle symmetry is in this case responsible for quantum interference. 7 refs., 3 figs.

  12. Colorimetric Solid-Phase Extractor

    NASA Technical Reports Server (NTRS)

    2003-01-01

    The heart of a colorimetric solid phase extractor (CSPE) test kit quickly measures the concentration of the biocides silver or iodine in astronauts' drinking water to determine whether concentrations are safe. When 10 milliliters (ml) of water is drawn through the disk, the disk will turn color (yellow in this picture for iodine) indicating the presence of the biocides. The device could someday be used to test water safety at reservoirs and water treatment plants on Earth. (photo credit: Microanalytical Instrumentation Center, Iowa State University).

  13. Single phase space laundry development

    NASA Technical Reports Server (NTRS)

    Colombo, Gerald V.; Putnam, David F.; Lunsford, Teddie D.; Streech, Neil D.; Wheeler, Richard R., Jr.; Reimers, Harold

    1993-01-01

    This paper describes a newly designed, 2.7 Kg (6 pound) capacity, laundry machine called the Single Phase Laundry (SPSL). The machine was designed to wash and dry crew clothing in a micro-gravity environment. A prototype unit was fabricated for NASA-JSC under a Small Business Innovated Research (SBIR) contract extending from September 1990 to January 1993. The unit employs liquid jet agitation, microwave vacuum drying, and air jet tumbling, which was perfected by KC-135 zero-g flight testing. Operation is completely automated except for loading and unloading clothes. The unit uses about 20 percent less power than a conventional household appliance.

  14. Reliability in the design phase

    SciTech Connect

    Siahpush, A.S.; Hills, S.W.; Pham, H.; Majumdar, D.

    1991-12-01

    A study was performed to determine the common methods and tools that are available to calculated or predict a system`s reliability. A literature review and software survey are included. The desired product of this developmental work is a tool for the system designer to use in the early design phase so that the final design will achieve the desired system reliability without lengthy testing and rework. Three computer programs were written which provide the first attempt at fulfilling this need. The programs are described and a case study is presented for each one. This is a continuing effort which will be furthered in FY-1992. 10 refs.

  15. Reliability in the design phase

    SciTech Connect

    Siahpush, A.S.; Hills, S.W.; Pham, H. ); Majumdar, D. )

    1991-12-01

    A study was performed to determine the common methods and tools that are available to calculated or predict a system's reliability. A literature review and software survey are included. The desired product of this developmental work is a tool for the system designer to use in the early design phase so that the final design will achieve the desired system reliability without lengthy testing and rework. Three computer programs were written which provide the first attempt at fulfilling this need. The programs are described and a case study is presented for each one. This is a continuing effort which will be furthered in FY-1992. 10 refs.

  16. Phase-covariant quantum benchmarks

    SciTech Connect

    Calsamiglia, J.; Aspachs, M.; Munoz-Tapia, R.; Bagan, E.

    2009-05-15

    We give a quantum benchmark for teleportation and quantum storage experiments suited for pure and mixed test states. The benchmark is based on the average fidelity over a family of phase-covariant states and certifies that an experiment cannot be emulated by a classical setup, i.e., by a measure-and-prepare scheme. We give an analytical solution for qubits, which shows important differences with standard state estimation approach, and compute the value of the benchmark for coherent and squeezed states, both pure and mixed.

  17. Phase VI Glove Durability Testing

    NASA Technical Reports Server (NTRS)

    Mitchell, Kathryn C.

    2010-01-01

    The current state-of-the-art space suit gloves, the Phase VI gloves, have an operational life of 25 - 8 hour Extravehicular Activities (EVAs) in a clean, controlled ISS environment. Future planetary outpost missions create the need for space suit gloves which can endure up to 90 - 8 hour traditional EVAs or 576 - 45 minute suit port-based EVAs in a dirty, uncontrolled planetary environment. Prior to developing improved space suit gloves for use in planetary environments, it is necessary to understand how the current state-of-the-art performs in these environments. The Phase VI glove operational life has traditionally been certified through cycle testing consisting of ISS-based tasks in a clean environment, and glove durability while performing planetary EVA tasks in a dirty environment has not previously been characterized. Testing was performed in the spring of 2010 by the NASA Johnson Space Center Crew and Thermal Systems Division to characterize the durability of the Phase VI Glove and identify areas of the glove design which need improvement to meet the requirements of future NASA missions. Lunar simulant was used in this test to help replicate the dirty lunar environment, and generic planetary surface EVA tasks were performed during testing. A total of 50 manned, pressurized test sessions were completed in the Extravehicular Mobility Unit (EMU) using one pair of Phase VI gloves as the test article. The 50 test sessions were designed to mimic the total amount of pressurized cycling the gloves would experience over a 6 month planetary outpost mission. The gloves were inspected at periodic intervals throughout testing, to assess their condition at various stages in the test and to monitor the gloves for failures. Additionally, motion capture and force data were collected during 18 of the 50 test sessions to assess the accuracy of the cycle model predictions used in testing and to feed into the development of improved cycle model tables. This paper provides a

  18. ZBLAN Fiber Phase B Study

    NASA Technical Reports Server (NTRS)

    Workman, Gary L.; Smith, Guy A.

    1997-01-01

    A Phase B feasibility study will be performed for the study of the effects of microgravity on the preform processing and fiber pulling of ZBLAN optical glass. Continuing from the positive results achieved in the fiber annealing experiments in 20 second intervals at 0.001 g on the KC-135 and the 5 minute experiments on the SPAR rocket, experiments will continue to work towards design of a fiber sting to initiate fiber pulling operations in space. Anticipated results include less homogeneous nucleation than ground-based annealed fibers. Infrared Fiber Systems and Galileo are the participating industrial investigators.

  19. Chopper-stabilized phase detector

    NASA Technical Reports Server (NTRS)

    Hopkins, P. M.

    1978-01-01

    Phase-detector circuit for binary-tracking loops and other binary-data acquisition systems minimizes effects of drift, gain imbalance, and voltage offset in detector circuitry. Input signal passes simultaneously through two channels where it is mixed with early and late codes that are alternately switched between channels. Code switching is synchronized with polarity switching of detector output of each channel so that each channel uses each detector for half time. Net result is that dc offset errors are canceled, and effect of gain imbalance is simply change in sensitivity.

  20. Studies of two phase flow

    NASA Technical Reports Server (NTRS)

    Witte, Larry C.

    1994-01-01

    The development of instrumentation for the support of research in two-phase flow in simulated microgravity conditions was performed. The funds were expended in the development of a technique for characterizing the motion and size distribution of small liquid droplets dispersed in a flowing gas. Phenomena like this occur in both microgravity and normal earth gravity situations inside of conduits that are carrying liquid-vapor mixtures at high flow rates. Some effort to develop a conductance probe for the measurement of liquid film thickness was also expended.

  1. Predictive thermodynamics for condensed phases.

    PubMed

    Glasser, Leslie; Jenkins, H Donald Brooke

    2005-10-01

    Thermodynamic information is central to assessment of the stability and reactivity of materials. However, because of both the demanding nature of experimental thermodynamics and the virtually unlimited number of conceivable compounds, experimental data is often unavailable or, for hypothetical materials, necessarily impossible to obtain. We describe simple procedures for thermodynamic prediction for condensed phases, both ionic and organic covalent, principally via formula unit volumes (or density); our volume-based approach (VBT) provides a new thermodynamic tool for such assessment. These methods, being independent of detailed knowledge of crystal structures, are applicable to liquids and amorphous materials as well as to crystalline solids. Examples of their use are provided. PMID:16172676

  2. Phase Change Fabrics Control Temperature

    NASA Technical Reports Server (NTRS)

    2009-01-01

    Originally featured in Spinoff in 1997, Outlast Technologies Inc. (formerly Gateway Technologies Inc.) has built its entire product line on microencapsulated phase change materials, developed in Small Business Innovation Research (SBIR) contracts with Johnson Space Center after initial development for the U.S. Air Force. The Boulder, Colorado-based company acquired the exclusive patent rights and now integrates these materials into textiles or onto finished apparel, providing temperature regulation in bedding materials and a full line of apparel for both ordinary and extreme conditions.

  3. Phase VI Glove Durability Testing

    NASA Technical Reports Server (NTRS)

    Mitchell, Kathryn

    2011-01-01

    The current state-of-the-art space suit gloves, the Phase VI gloves, have an operational life of 25 -- 8 hour Extravehicular Activities (EVAs) in a dust free, manufactured microgravity EVA environment. Future planetary outpost missions create the need for space suit gloves which can endure up to 90 -- 8 hour traditional EVAs or 576 -- 45 minute suit port-based EVAs in a dirty, uncontrolled planetary environment. Prior to developing improved space suit gloves for use in planetary environments, it is necessary to understand how the current state-of-the-art performs in these environments. The Phase VI glove operational life has traditionally been certified through cycle testing consisting of International Space Station (ISS)-based EVA tasks in a clean environment, and glove durability while performing planetary EVA tasks in a dirty environment has not previously been characterized. Testing was performed in the spring of 2010 by the NASA Johnson Space Center (JSC) Crew and Thermal Systems Division (CTSD) to characterize the durability of the Phase VI Glove and identify areas of the glove design which need improvement to meet the requirements of future NASA missions. Lunar simulant was used in this test to help replicate the dirty lunar environment, and generic planetary surface EVA tasks were performed during testing. A total of 50 manned, pressurized test sessions were completed in the Extravehicular Mobility Unit (EMU) using one pair of Phase VI gloves as the test article. The 50 test sessions were designed to mimic the total amount of pressurized cycling the gloves would experience over a 6 month planetary outpost mission. The gloves were inspected periodically throughout testing, to assess their condition at various stages in the test and to monitor the gloves for failures. Additionally, motion capture and force data were collected during 18 of the 50 test sessions to assess the accuracy of the cycle model predictions used in testing and to feed into the

  4. Phase conjugated slab laser designator

    SciTech Connect

    Chandra, S.; Paul, J.L.

    1989-06-06

    A laser designator is described comprising a laser pump means; a high power phase conjugated slab laser amplifier formed of GSGG:Cr:Nd as a lasing material on one side of the pump means; a low power rod shaped laser oscillator on the opposite side of the pump means; and a first plurality of optical reflecting and refracting means for directing and shaping a laser beam which surrounds the pump means and passes through the rod and slab; and a telescope means coupled to the beam to direct it to a distant target.

  5. Airborne electronically steerable phased array

    NASA Technical Reports Server (NTRS)

    1972-01-01

    The results are presented of the second stage of a program for the design and development of a phased array capable of simultaneous and separate transmission and reception of radio frequency signals at S-band frequencies. The design goals of this stage were the development of three major areas of interest required for the final prototype model. These areas are the construction and testing of the low-weight, full-scale 128-element array of antenna elements, the development of the RF manifold feed system, and the construction and testing of a working module containing diplexer and transmit and receive circuits.

  6. Solid phase microextraction field kit

    DOEpatents

    Nunes, Peter J.; Andresen, Brian D.

    2005-08-16

    A field kit for the collection, isolation and concentration of trace amounts of high explosives (HE), biological weapons (BW) and chemical weapons (CW) residues in air, soil, vegetation, swipe, and liquid samples. The field kit includes a number of Solid Phase Microextraction (SPME) fiber and syringe assemblies in a hermetically sealed transportation container or tubes which includes a sampling port, a number of extra SPME fiber and syringe assemblies, the fiber and syringe assemblies including a protective cap for the fiber, and an extractor for the protective cap, along with other items including spare parts, protective glove, and an instruction manual, all located in an airtight container.

  7. Automatic contrast phase estimation in CT volumes.

    PubMed

    Sofka, Michal; Wu, Dijia; Sühling, Michael; Liu, David; Tietjen, Christian; Soza, Grzegorz; Zhou, S Kevin

    2011-01-01

    We propose an automatic algorithm for phase labeling that relies on the intensity changes in anatomical regions due to the contrast agent propagation. The regions (specified by aorta, vena cava, liver, and kidneys) are first detected by a robust learning-based discriminative algorithm. The intensities inside each region are then used in multi-class LogitBoost classifiers to independently estimate the contrast phase. Each classifier forms a node in a decision tree which is used to obtain the final phase label. Combining independent classification from multiple regions in a tree has the advantage when one of the region detectors fail or when the phase training example database is imbalanced. We show on a dataset of 1016 volumes that the system correctly classifies native phase in 96.2% of the cases, hepatic dominant phase (92.2%), hepatic venous phase (96.7%), and equilibrium phase (86.4%) in 7 seconds on average. PMID:22003696

  8. Antenna-array, phase quadrature tracking system

    NASA Technical Reports Server (NTRS)

    Cubley, H. D.

    1970-01-01

    Phase relationship between input signals appearing on widely-spaced parallel connected antenna elements in array is automatically adjusted in phase quadrature tracking system. Compact and lightweight design permit use in wide variety of airborne communications networks.

  9. Purification of biomaterials by phase partitioning

    NASA Technical Reports Server (NTRS)

    Harris, J. M.

    1984-01-01

    A technique which is particularly suited to microgravity environments and which is potentially more powerful than electrophoresis is phase partitioning. Phase partitioning is purification by partitioning between the two immiscible aqueous layers formed by solution of the polymers poly(ethylene glycol) and dextran in water. This technique proved to be very useful for separations in one-g but is limited for cells because the cells are more dense than the phase solutions thus tend to sediment to the bottom of the container before reaching equilibrium with the preferred phase. There are three phases to work in this area: synthesis of new polymers for affinity phase partitioning; development of automated apparatus for ground-based separations; and design of apparatus for performing simple phase partitioning space experiments, including examination of mechanisms for separating phases in the absence of gravity.

  10. Phase diagrams of bosonic ABn chains

    NASA Astrophysics Data System (ADS)

    Cruz, G. J.; Franco, R.; Silva-Valencia, J.

    2016-04-01

    The A B N - 1 chain is a system that consists of repeating a unit cell with N sites where between the A and B sites there is an energy difference of λ. We considered bosons in these special lattices and took into account the kinetic energy, the local two-body interaction, and the inhomogenous local energy in the Hamiltonian. We found the charge density wave (CDW) and superfluid and Mott insulator phases, and constructed the phase diagram for N = 2 and 3 at the thermodynamic limit. The system exhibited insulator phases for densities ρ = α/ N, with α being an integer. We obtained that superfluid regions separate the insulator phases for densities larger than one. For any N value, we found that for integer densities ρ, the system exhibits ρ + 1 insulator phases, a Mott insulator phase, and ρ CDW phases. For non-integer densities larger than one, several CDW phases appear.

  11. Constant-amplitude, frequency- independent phase shifter

    NASA Technical Reports Server (NTRS)

    Deboo, G. J.

    1971-01-01

    Electronic circuit using operational amplifiers provides output with constant phase shift amplitude, with respect to sinusoidal input, over wide range of frequencies. New circuit includes field effect transistor, Q, operational amplifiers, A1 and A2, and phase detector.

  12. Phase Detector for Power-Factor Controller

    NASA Technical Reports Server (NTRS)

    Nola, F. J.

    1984-01-01

    Positive feedback assures reliable switching. Three Phase Power Factor Controller includes three phase detectors, each produces rectangular waves of duration approximately equal to lag time between line voltage and motor current.

  13. Polarized gravitational waves from cosmological phase transitions

    NASA Astrophysics Data System (ADS)

    Kisslinger, Leonard; Kahniashvili, Tina

    2015-08-01

    We estimate the degree of circular polarization for the gravitational waves generated during the electroweak and QCD phase transitions from the kinetic and magnetic helicity generated by bubble collisions during those cosmological phase transitions.

  14. Space shuttle phase B study plan

    NASA Technical Reports Server (NTRS)

    Hello, B.

    1971-01-01

    Phase B emphasis was directed toward development of data which would facilitate selection of the booster concept, and main propulsion system for the orbiter. A shuttle system is also defined which will form the baseline for Phase C program activities.

  15. Phase transformations during the growth of paracetamol crystals from the vapor phase

    NASA Astrophysics Data System (ADS)

    Belyaev, A. P.; Rubets, V. P.; Antipov, V. V.; Bordei, N. S.

    2014-07-01

    Phase transformations during the growth of paracetamol crystals from the vapor phase are studied by differential scanning calorimetry. It is found that the vapor-crystal phase transition is actually a superposition of two phase transitions: a first-order phase transition with variable density and a second-order phase transition with variable ordering. The latter, being a diffuse phase transition, results in the formation of a new, "pretransition," phase irreversibly spent in the course of the transition, which ends in the appearance of orthorhombic crystals. X-ray diffraction data and micrograph are presented.

  16. Information Display System for Atypical Flight Phase

    NASA Technical Reports Server (NTRS)

    Statler, Irving C. (Inventor); Ferryman, Thomas A. (Inventor); Amidan, Brett G. (Inventor); Whitney, Paul D. (Inventor); White, Amanda M. (Inventor); Willse, Alan R. (Inventor); Cooley, Scott K. (Inventor); Jay, Joseph Griffith (Inventor); Lawrence, Robert E. (Inventor); Mosbrucker, Chris J. (Inventor); Rosenthal, Loren J. (Inventor); Lynch, Robert E. (Inventor); Chidester, Thomas R. (Inventor); Prothero, Gary L. (Inventor); Andrei, Adi (Inventor); Romanowski, Timothy P. (Inventor); Robin, Daniel E. (Inventor); Prothero, Jason W. (Inventor)

    2007-01-01

    Method and system for displaying information on one or more aircraft flights, where at least one flight is determined to have at least one atypical flight phase according to specified criteria. A flight parameter trace for an atypical phase is displayed and compared graphically with a group of traces, for the corresponding flight phase and corresponding flight parameter, for flights that do not manifest atypicality in that phase.

  17. Phase transition dynamics and gravitational waves

    SciTech Connect

    Megevand, Ariel

    2009-04-20

    During a first-order phase transition, gravitational radiation is generated either by bubble collisions or by turbulence. For phase transitions which took place at the electroweak scale and beyond, the signal is expected to be within the sensitivity range of planned interferometers such as LISA or BBO. We review the generation of gravitational waves in a first-order phase transition and discuss the dependence of the spectrum on the dynamics of the phase transition.

  18. Bandwidth controller for phase-locked-loop

    NASA Technical Reports Server (NTRS)

    Brockman, Milton H. (Inventor)

    1992-01-01

    A phase locked loop utilizing digital techniques to control the closed loop bandwidth of the RF carrier phase locked loop in a receiver provides high sensitivity and a wide dynamic range for signal reception. After analog to digital conversion, a digital phase locked loop bandwidth controller provides phase error detection with automatic RF carrier closed loop tracking bandwidth control to accommodate several modes of transmission.

  19. Catalyst and method for aqueous phase reactions

    DOEpatents

    Elliott, Douglas C.; Hart, Todd R.

    1999-01-01

    The present invention is a catalyst in the form of a plurality of porous particles wherein each particle is a support having nickel metal catalytic phase or reduced nickel deposited thereon in a first dispersed phase and an additional metal deposited onto the support in a second dispersed phase. The additional metal is effective in retarding or reducing agglomeration or sintering of the nickel metal catalytic phase without substantially affecting the catalytic activity, thereby increasing the life time of the catalyst.

  20. Infrared phased-array sensor

    NASA Astrophysics Data System (ADS)

    Slovick, Brian A.; Bean, Jeffrey A.; Florence, Lou A.; Boreman, Glenn D.

    2011-06-01

    Metal-oxide-metal (MOM) tunnel diode detectors when integrated with phased-array antennas provide determination of the angle of arrival and degree of coherence of received infrared radiation. Angle-of-arrival measurements are made with a pair of dipole antennas coupled to a MOM diode through a coplanar strip transmission line. The direction of maximum angular response is altered by varying the position of the MOM diode along the transmission line connecting the antenna elements. Phased-array antennas can also be used to measure the degree of coherence of a partially coherent infrared field. With a two-element array, the degree of coherence is a measure of the correlation of electric fields received by the antennas as a function of the element separation. Antenna-coupled MOM diode devices are fabricated using electron beam lithography and thin-film deposition through a resist shadow mask. Measurements at 10.6 μm are substantiated by electromagnetic simulations and compared to analytic results.