Science.gov

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. Irradiation-induced formation of nanocrystallites with C15 Laves phase structure in bcc iron.

    PubMed

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

    2012-01-13

    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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. Thermoelectric properties of TbFe2 and TbCo2 in C15- laves phase: Spin-polarized DFT+U approach

    NASA Astrophysics Data System (ADS)

    Reshak, A. H.

    2017-01-01

    Thermoelectric properties of materials are intimately related to their electronic band structure. Combining first- and second-principles calculations, we have obtained the transport properties for the spin-up and spin-down electrons of the laves phase TbFe2 and TbCo2 compounds. The unique band structure feature and the density of states at Fermi level (EF) promote the EF to a point where carriers are in energetic proximity to these features. The non-zero density of states at EF for the spin-up (↑) and spin-down (↓) electrons leads to unusual transport properties because both the (↑) and (↓) densities contributes to the states at EF. The parabolic bands in the vicinity of EF enhance the carriers mobility and hence the transport properties of TbFe2 and TbCo2. Calculations show that the spin-up/down transport coefficients are temperature-dependent. It has been found that TbCo2 possess larger Seebeck coefficient than that of TbFe2 and hence the power factor. The calculated Seebeck coefficient of TbCo2 agree well with the available experimental data.

  10. NMR relaxation rate studies of molecular motions in NaSn, the Laves-phase metal hydride C15-ZrCr(2)H(x) and carbon/epoxy composite materials

    NASA Astrophysics Data System (ADS)

    Stoddard, Ronald Dean

    Here I present studies of molecular motions in three very different systems: NaSn, which exhibits motion characteristic of both a superionic conductor and a rotor crystal; C15-ZrCrsb2Hsbx (x < 0.5), a metal hydride which exhibits unusual characteristics in its hydrogen motion; and, finally a study of the relationship between Tsb2 and the degree of cure of carbon/epoxy materials. NaSn is characterized by Nasp+ ions and stable (Snsb4)sp{4-} tetrahedra. At high temperatures NaSn displays a disordered solid phase (alpha-NaSn). The presence of Nasp+ ions suggests that alpha-NaSn may be a superionic conductor (translationally disordered) and the presence of stable Snsb4 tetrahedra suggests it may be a rotor crystal (organizationally disordered). The purpose of this study is to gain better understanding of the motions in alpha-NaSn by monitoring Na and Sn motion using sp{23}Na and sp{119}Sn NMR, respectively. C15-ZrCrsb2Hsbx (x < 0.5) is a Laves phase metal hydride which displays extremely rapid hydrogen motion and a Tsb1 peak which cannot be explained by a model employing a single correlation time for the motion. A model employing a Gaussian distribution of correlation times has been used to successfully fit Tsb1, but the origin of this distribution in a crystalline solid solution is not known. The purpose of this study is to better understand the low temperature hydrogen motions occurring in C15-ZrCrsb2Hsbx by extending the previous NMR measurements using Tsb1p and Tsb1D, experiments which effectively push the relaxation peak to lower temperatures. New techniques for manufacturing carbon/epoxy components are under development which require partial curing of the material. At present, no method for monitoring partial curing exists. Tsb2 is a promising monitor of degree of cure because of its sensitivity to changes rates of molecular motions. The purpose of this study is to demonstrate the sensitivity of Tsb2 to changes in molecular motion due to curing, and to find a

  11. 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...

  12. 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...

  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. 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.

  15. C15orf48 — EDRN Public Portal

    Cancer.gov

    C15orf48 is expressed mainly in adult stomach, placenta, small intestine and colon, as well as in normal mucosa of esophagus. The gene was first identified in a study of human esophageal squamous cell carcinoma tissues. Levels of both the message and protein are reduced in carcinoma samples. Alternatively spliced transcript variants that encode the same protein have been identified.

  16. 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...

  17. 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...

  18. 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...

  19. 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...

  20. 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...

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

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... companies. 1.381(c)(15)-1 Section 1.381(c)(15)-1 Internal Revenue INTERNAL REVENUE SERVICE, DEPARTMENT OF...)-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...

  2. 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

  3. 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.

  4. Correcting the Redshift Measurement of 4C15.05 Using Neutral Hydrogen

    NASA Astrophysics Data System (ADS)

    Jones, Kristen M.; Ghosh, Tapasi; Salter, Christopher J.

    2017-01-01

    4C15.05, (also known as PKS 0202+14 or J0204+15), is a quintessential blazar. It has a flat radio spectrum, a super-luminal jet and gamma-ray detections. Arecibo observations with the experimental 700-800 MHz receiver on the 305-m diameter William E. Gordon Telescope detected, serendipitously, HI in absorption against 4C15.05 while using it as a bandpass calibrator for another object in an HI absorption project. Although the redshift we derive is different to than that attributed to 4C15.05 by Perlman et al. (1998), it agrees very well with the value of z=0.833 determined by Stickel et al. (1996). We note that the erroneous value of z=0.405 has been extensively used in the literature.

  5. 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..., Internal Revenue Code of 1954) § 31.3306(c)(15)-1 Services in delivery or distribution of newspapers... under the age of 18 in the delivery or distribution of newspapers or shopping news, not...

  6. 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..., Internal Revenue Code of 1954) § 31.3306(c)(15)-1 Services in delivery or distribution of newspapers... under the age of 18 in the delivery or distribution of newspapers or shopping news, not...

  7. 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..., Internal Revenue Code of 1954) § 31.3306(c)(15)-1 Services in delivery or distribution of newspapers... under the age of 18 in the delivery or distribution of newspapers or shopping news, not...

  8. 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..., Internal Revenue Code of 1954) § 31.3306(c)(15)-1 Services in delivery or distribution of newspapers... under the age of 18 in the delivery or distribution of newspapers or shopping news, not...

  9. 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..., Internal Revenue Code of 1954) § 31.3306(c)(15)-1 Services in delivery or distribution of newspapers... under the age of 18 in the delivery or distribution of newspapers or shopping news, not...

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

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 26 Internal Revenue 7 2012-04-01 2012-04-01 false Mutual insurance companies or associations. 1... 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...

  11. 26 CFR 1.501(c)(15)-1 - Mutual insurance companies or associations.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 26 Internal Revenue 7 2010-04-01 2010-04-01 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...

  12. 26 CFR 1.501(c)(15)-1 - Mutual insurance companies or associations.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 26 Internal Revenue 7 2014-04-01 2013-04-01 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...

  13. 26 CFR 1.501(c)(15)-1 - Mutual insurance companies or associations.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 26 Internal Revenue 7 2013-04-01 2013-04-01 false Mutual insurance companies or associations. 1... 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...

  14. 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...

  15. On the shear homeotypism in the MgCu 2 family

    NASA Astrophysics Data System (ADS)

    Schubert, K.

    1984-07-01

    It is well known that there are several homeotypes of MgCu 2 which are distinguished by different shears between double layers of atoms parallel to (111) MgCu 2 (Friauf-Laves phases) and that they are stable at specific valence electron concentrations (rule of Komura). This phenomenon may be interpreted by the two-correlations model, a valence model for metallic phases. The correlation of the peripheral core electrons ( c correlation) and its commensurability to the crystal cell a is the same for all quasi-homologous shear homeotypes of MgCu 2, but the correlation of the valence electrons ( b correlation) depends on the valence-electron concentration. The b correlation exhibits different discrete commensurabilities with respect to the c correlation in the hexagonal basal plane of a. Also, the distances of the b correlation planes parallel to the hexagonal basal plane exhibit energetically favorable commensurabilities to a. These different commensurabilities correspond to observed phases. The b electron correlation induces transitory electrical dipole vectors at the atoms with component in a3 direction (the hexagonal axis) and the interactions of the dipoles determine the stacking sequence of the double layers.

  16. 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.

  17. 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.

  18. eis Promoter C14G and C15G Mutations Do Not Confer Kanamycin Resistance in Mycobacterium tuberculosis.

    PubMed

    Pholwat, Suporn; Stroup, Suzanne; Heysell, Scott; Ogarkov, Oleg; Zhdanova, Svetlana; Ramakrishnan, Girija; Houpt, Eric

    2016-12-01

    We studied the significance of particular eis mutations on Mycobacterium tuberculosis drug resistance using a specialized transduction strategy. Recombinant strains harboring eis promoter mutations C14T, C12T, and G10A exhibited kanamycin resistance with MICs of 40, 10, and 20 μg/ml, respectively, while recombinant strains harboring C14G and C15G mutations were kanamycin susceptible (MIC, 2.5 to 5 μg/ml). Each of the eis mutants tested remained amikacin susceptible (MIC, 0.5 to 4 μg/ml). The identification of specific eis mutations is needed for accurate genotypic susceptibility testing for kanamycin.

  19. Deformation mechanisms in a Laves phase

    SciTech Connect

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

    1992-12-31

    The stress-induced phase transformation between C36 and C15 structures in Fe{sub 2}Zr is studied by electron microscopy. Nucleus of transformation is believed to be pre-existing C15 layers in C36 particles. Microstructural evidence for three mechanisms of growth of a new phase were found: Fault accumulation and rearrangement, moving of a individual partial dislocations between two phases, and the migration of microscopic ledges composed of a series of Shockley partials between C36 and C15. Plastic deformation by slip on non-basal planes of C36 caused by indentation is studied.

  20. 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.

  1. 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

  2. Nitrogen Fertilizer and Straw Applications Affect Uptake of 13C,15N-Glycine by Soil Microorganisms in Wheat Growth Stages.

    PubMed

    Yang, Lijie; Zhang, Lili; Yu, Chunxiao; Li, Dongpo; Gong, Ping; Xue, Yan; Song, Yuchao; Cui, Yalan; Doane, Timothy A; Wu, Zhijie

    2017-01-01

    This study investigated the influence of nitrogen (N) fertilizer and straw on intact amino acid N uptake by soil microorganisms and the relationship between amino acid turnover and soil properties during the wheat growing season. A wheat pot experiment was carried out with three treatments: control (CK), N fertilizer (NF) and N fertilizer plus rice straw (NS). We used stable isotope compound-specific analysis to determine the uptake of 13C,15N-glycine by soil microorganisms. In the NF treatment, microbial 13C,15N-glycine uptake was lower compared with CK, suggesting that inorganic N was the preferred N source for soil microorganisms. However, The application of straw with N fertilizer (in NS treatment) increased microbial 13C,15N-glycine uptake even with the same amount of N fertilizer application. In this treatment, enzyme activities, soil microbial biomass C and microbial biomass N increased simultaneously because more C was available. Soil mineral N and plant N contents all decreased substantially. The increased uptake of intact 13C,15N-glycine in the NS treatment can be attributed to direct assimilation by soil microorganisms to satisfy the demand for N when inorganic N was consumed.

  3. Nitrogen Fertilizer and Straw Applications Affect Uptake of 13C,15N-Glycine by Soil Microorganisms in Wheat Growth Stages

    PubMed Central

    Yu, Chunxiao; Li, Dongpo; Gong, Ping; Xue, Yan; Song, Yuchao; Cui, Yalan; Doane, Timothy A.; Wu, Zhijie

    2017-01-01

    This study investigated the influence of nitrogen (N) fertilizer and straw on intact amino acid N uptake by soil microorganisms and the relationship between amino acid turnover and soil properties during the wheat growing season. A wheat pot experiment was carried out with three treatments: control (CK), N fertilizer (NF) and N fertilizer plus rice straw (NS). We used stable isotope compound-specific analysis to determine the uptake of 13C,15N-glycine by soil microorganisms. In the NF treatment, microbial 13C,15N-glycine uptake was lower compared with CK, suggesting that inorganic N was the preferred N source for soil microorganisms. However, The application of straw with N fertilizer (in NS treatment) increased microbial 13C,15N-glycine uptake even with the same amount of N fertilizer application. In this treatment, enzyme activities, soil microbial biomass C and microbial biomass N increased simultaneously because more C was available. Soil mineral N and plant N contents all decreased substantially. The increased uptake of intact 13C,15N-glycine in the NS treatment can be attributed to direct assimilation by soil microorganisms to satisfy the demand for N when inorganic N was consumed. PMID:28045989

  4. 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

  5. Exogenous Isoleucine and Fatty Acid Shortening Ensure the High Content of Anteiso-C15:0 Fatty Acid Required for Low-Temperature Growth of Listeria monocytogenes

    PubMed Central

    Zhu, Kun; Ding, Xiang; Julotok, Mudcharee; Wilkinson, Brian J.

    2005-01-01

    Previous studies have demonstrated that the branched-chain fatty acid anteiso-C15:0 plays a critical role in the growth of Listeria monocytogenes at low temperatures by ensuring sufficient membrane fluidity. Studies utilizing a chemically defined minimal medium revealed that the anteiso fatty acid precursor isoleucine largely determined the fatty acid profile and fatty acid response of the organism to lowered growth temperature. When isoleucine was sufficient, the fatty acid profile was very uniform, with anteiso fatty acids comprising up to 95% of total fatty acid, and the major fatty acid adjustment to low temperature was fatty acid chain shortening, which resulted in an increase of anteiso-C15:0 solely at the expense of anteiso-C17:0. When isoleucine was not supplied, the fatty acid profile became more complex and was readily modified by leucine, which resulted in a significant increase of corresponding iso fatty acids and an inability to grow at 10°C. Under this condition, the increase of anteiso-C15:0 at low temperature resulted from the combined effect of increasing the anteiso:iso ratio and chain shortening. A branched-chain α-keto acid dehydrogenase-defective strain largely lost the ability to increase the anteiso:iso ratio. Cerulenin, an inhibitor of β-ketoacyl-acyl carrier protein synthase (FabF), induced a similar fatty acid chain shortening as low temperature did. We propose that the anteiso precursor preferences of enzymes in the branched-chain fatty acid biosynthesis pathway ensure a high production of anteiso fatty acids, and cold-regulated chain shortening results in a further increase of anteiso-C15:0 at the expense of anteiso-C17:0. PMID:16332779

  6. Asymmetric total synthesis of (+)-bermudenynol, a C15 Laurencia metabolite with a vinyl chloride containing oxocene skeleton, through intramolecular amide enolate alkylation.

    PubMed

    Kim, Gyudong; Sohn, Te-Ik; Kim, Deukjoon; Paton, Robert S

    2014-01-03

    A substrate-controlled asymmetric total synthesis of (+)-bermudenynol, a compact and synthetically challenging C15 Laurencia metabolite that contains several halogen atoms, is reported. The oxocene core, which contains a vinyl chloride, was constructed by an efficient and highly stereoselective intramolecular amide enolate alkylation (IAEA). This result showcases the broad utility of the IAEA methodology as a useful alternative for cases in which the ring-closing metathesis is inefficient.

  7. Intramolecular N-Glycan/Polypeptide Interactions Observed at Multiple N-Glycan Remodeling Steps through [13C,15N]-N-Acetylglucosamine Labeling of Immunoglobulin G1

    PubMed Central

    2014-01-01

    Asparagine-linked (N) glycosylation is a common eukaryotic protein modification that affects protein folding, function, and stability through intramolecular interactions between N-glycan and polypeptide residues. Attempts to characterize the structure–activity relationship of each N-glycan are hindered by inherent properties of the glycoprotein, including glycan conformational and compositional heterogeneity. These limitations can be addressed by using a combination of nuclear magnetic resonance techniques following enzymatic glycan remodeling to simultaneously generate homogeneous glycoforms. However, widely applicable methods do not yet exist. To address this technological gap, immature glycoforms of the immunoglobulin G1 fragment crystallizable (Fc) were isolated in a homogeneous state and enzymatically remodeled with [13C,15N]-N-acetylglucosamine (GlcNAc). UDP-[13C,15N]GlcNAc was synthesized enzymatically in a one-pot reaction from [13C]glucose and [15N-amido]glutamine. Modifying Fc with recombinantly expressed glycosyltransferases (Gnt1 and Gnt2) and UDP-[13C,15N]GlcNAc resulted in complete glycoform conversion as judged by mass spectrometry. Two-dimensional heteronuclear single-quantum coherence spectra of the Gnt1 product, containing a single [13C,15N]GlcNAc residue on each N-glycan, showed that the N-glycan is stabilized through interactions with polypeptide residues. Similar spectra of homogeneous glycoforms, halted at different points along the N-glycan remodeling pathway, revealed the presence of an increased level of interaction between the N-glycan and polypeptide at each step, including mannose trimming, as the N-glycan was converted to a complex-type, biantennary form. Thus, conformational restriction increases as Fc N-glycan maturation proceeds. Gnt1 and Gnt2 catalyze fundamental reactions in the synthesis of every glycoprotein with a complex-type N-glycan; thus, the strategies presented herein can be applied to a broad range of glycoprotein

  8. Amino acids as a nitrogen source in temperate upland grasslands: the use of dual labelled ((13)C, (15)N) glycine to test for direct uptake by dominant grasses.

    PubMed

    Streeter, T C; Bol, R; Bardgett, R D

    2000-01-01

    It is becoming increasingly apparent that soil amino acids are a principal source of nitrogen (N) for certain plants, and especially those of N-limited environments. This study of temperate upland grasslands used glycine-2-(13)C-(15)N and ((15)NH4)(2)SO(4) labelling techniques to test the hypothesis that plant species which dominate 'unimproved' semi-natural grasslands (Festuca-Agrostis-Galium) are able to utilise amino acid N for growth, whereas those plants which dominate 'improved' grasslands (Lolium-Cynosurus), that receive regular applications of inorganic fertiliser, use inorganic N forms as their main N source. Data from field experiments confirmed that 'free' amino acids were more abundant in 'unimproved' than 'improved' grassland and that glycine was the dominant amino acid type (up to 42% of total). Secondly, the injection of representative amounts of glycine-2-(13)C-(15)N (4.76 and 42.86 mM) into intact soil cores from the two grassland types provided evidence of direct uptake of glycine by plants, with both (15)N and (13)C being detected in plant material of both grasslands. Finally, a microcosm experiment demonstrated no preferential uptake of amino acid N by the grasses which dominate the grassland types, namely Holcus lanatus, Festuca rubra, Agrostis capillaris from the 'unimproved' grassland, and Lolium perenne from the 'improved' grassland. Again, both (13)C and (15)N were detected in all grass species suggesting uptake of intact glycine by these plants.

  9. 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

  10. Efficient Measurement of 3JN,Cγ and 3JC‧,Cγ Coupling Constants of Aromatic Residues in 13C, 15N-Labeled Proteins

    NASA Astrophysics Data System (ADS)

    Löhr, Frank; Rüterjans, Heinz

    2000-09-01

    An NMR pulse sequence is proposed for the simultaneous determination of side chain χ1 torsion-angle related 3JN,Cγ and 3JC‧,Cγ couplings in aromatic amino acid spin systems. The method is of the quantitative J correlation type and takes advantage of attenuated 15N and 1H transverse relaxation by means of the TROSY principle. Unlike previously developed schemes for the measurement of either of the two coupling types, spectra contain internal reference peaks that are usually recorded in separate experiments. Therefore, the desired information is extracted from a single rather than four data sets. The new method is demonstrated with uniformly 13C/15N labeled Desulfovibrio vulgaris flavodoxin, which contains 14 aromatic out of 147 total amino acid residues.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. Corrosion Behavior of Fe41Co7Cr15Mo14C15B6Y2 Bulk Metallic Glass in Sulfuric Acid Solutions

    NASA Astrophysics Data System (ADS)

    Fan, H. B.; Zheng, W.; Wang, G. Y.; Liaw, P. K.; Shen, J.

    2011-06-01

    An Fe41Co7Cr15Mo14C15B6Y2 bulk metallic glass with a diameter of 5 mm was prepared with the copper-mold-casting method. The corrosion resistance of this amorphous steel in sulfuric-acid solutions was determined by electrochemical measurements. The passive film formed on the surface of the alloy after immersion in the 0.5-mol/l H2SO4 solution for 1 week was analyzed by X-ray photoelectron spectroscopy (XPS). Electrochemical measurements show that the corrosion resistance of the amorphous steel in the 1 mol/l-H2SO4 solution is superior to a stainless steel (SUS 321), and is almost the same as Ti6Al4V, which shows that the amorphous steel has an excellent corrosion resistance in sulfuric-acid solutions. As the concentration of the sulfuric-acid solutions increases from 0.5 mol/l to 4 mol/l, the corrosion resistance of the amorphous steel decreases. The XPS result reveals that a bilayer structure of protective film formed on the surface of the amorphous steel in a H2SO4 solution. The compositions of the inner part of the film are MoO2, Cr2O3, CoO, and FeO, and those of the outer film are MoO3, Cr(OH)3, Co(OH)2, and Fe(OH)3.

  16. Elemental formula annotation of polar and lipophilic metabolites using (13) C, (15) N and (34) S isotope labelling, in combination with high-resolution mass spectrometry.

    PubMed

    Giavalisco, Patrick; Li, Yan; Matthes, Annemarie; Eckhardt, Aenne; Hubberten, Hans-Michael; Hesse, Holger; Segu, Shruthi; Hummel, Jan; Köhl, Karin; Willmitzer, Lothar

    2011-10-01

    The unbiased and comprehensive analysis of metabolites in any organism presents a major challenge if proper peak annotation and unambiguous assignment of the biological origin of the peaks are required. Here we provide a comprehensive multi-isotope labelling-based strategy using fully labelled (13) C, (15) N and (34) S plant tissues, in combination with a fractionated metabolite extraction protocol. The extraction procedure allows for the simultaneous extraction of polar, semi-polar and hydrophobic metabolites, as well as for the extraction of proteins and starch. After labelling and extraction, the metabolites and lipids were analysed using a high-resolution mass spectrometer providing accurate MS and all-ion fragmentation data, providing an unambiguous readout for every detectable isotope-labelled peak. The isotope labelling assisted peak annotation process employed can be applied in either an automated database-dependent or a database-independent analysis of the plant polar metabolome and lipidome. As a proof of concept, the developed methods and technologies were applied and validated using Arabidopsis thaliana leaf and root extracts. Along with a large repository of assigned elemental compositions, which is provided, we show, using selected examples, the accuracy and reliability of the developed workflow.

  17. Quantitative role of splanchnic region in leucine metabolism: L-(1-13C,15N)leucine and substrate balance studies

    SciTech Connect

    Yu, Y.M.; Wagner, D.A.; Tredget, E.E.; Walaszewski, J.A.; Burke, J.F.; Young, V.R. )

    1990-07-01

    The role of the splanchnic region (Sp) in whole body leucine metabolism was assessed in six chronically catheterized fasting mongrel dogs and in eight dogs during constant enteral feeding of a complete amino acid solution (0.24 g.kg-1.h-1). We used primed continuous intravenous infusions of L-(1-13C,15N)leucine and L-(1-14C)leucine and measurements of arteriovenous isotope and leucine balance across the gut, liver, and Sp. In the fasted condition, 3.5% of arterial leucine supply was oxidized in the Sp, accounting for 13% of total body leucine oxidation, with 10% by liver. With amino acid feeding (1) leucine carbon and nitrogen fluxes and oxidation were increased (P less than 0.01) at the whole body level; (2) the percent of whole body leucine oxidation occurring in the Sp and liver increased (P less than 0.01) to 41 and 27%, respectively; (3) fractional metabolic utilization of leucine delivered to the Sp was reduced (P less than 0.01) from 47 to 35%; (4) the deamination rate of leucine in the gut was increased (P less than 0.05), along with an increased reamination rate of alpha-ketoisocaproic acid in the Sp (P less than 0.05). These findings reveal that the Sp accounts for a small fraction of whole body leucine oxidation during the fasting condition, but it plays a quantitatively important role in total body leucine oxidation during amino acid feeding; the gut and liver play cooperative roles in controlling leucine supply to peripheral tissues.

  18. Emission rates of C 8-C 15 VOCs from seaweed and sand in the inter-tidal zone at Mace Head, Ireland

    NASA Astrophysics Data System (ADS)

    Sartin, J. H.; Halsall, C. J.; Hayward, S.; Hewitt, C. N.

    Emission fluxes for a range of C 8-C 15 volatile organic compounds (VOCs) were determined from the seaweed Fucus spiralis (spiral wrack) and an adjacent sand surface during low tide on the coastline of Mace Head, Ireland. These two surface types, assessed using dynamic flux chamber systems, are typical of the Mace Head inter-tidal zone. A range of n-alkanes and oxygenates were routinely identified in the measurement of chamber air. Examination of the odd/even n-alkane ratios and use of the carbon preference index (CPI) suggested a biogenic source for these compounds (CPIs >2 in for all samples). Fluxes of n-pentadecane, the most predominant n-alkane, ranged from 0.2 to 5.1 μg m -2 h -1 (0.9-24 nmol m -2 h -1), while oxygenates such as nonanal and decanal had fluxes ranging from <0.1 to 4.4 μg m -2 h -1 (<0.1-31 nmol m -2 h -1) and <0.1 to 4.6 μg m -2 h -1 (<0.1-30 nmol m -2 h -1), respectively. Seaweed emission rates for n-pentadecane were correlated with photosynthetically active radiation (PAR) ( rs=0.94) while emissions from sand showed correlation with temperature ( rs=0.85). This suggests a possible biochemical route controlling the release of n-pentadecane from spiral wrack, and temperature-driven volatilisation from sand. Volatilisation from residual seawater trapped in the sand may explain the comparable flux of both n-alkanes and oxygenates from this surface. Unlike the n-alkanes, oxygenate fluxes from sand correlate with PAR, suggesting a photodependent production from organic carbon residues present in seawater. Comparison with previous flux estimates from coastal seawater indicates that the two source types ( Fucus spiralis and bare sand) are significant but not dominant sources of these VOCs.

  19. 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.

  20. First principles total energy study of NbCr{sub 2} + V Laves phase ternary system

    SciTech Connect

    Ormeci, A.; Chen, S.P.; Wills, J.M.; Albers, R.C.

    1999-04-01

    The C15 NbCr{sub 2} + V Laves phase ternary system is studied by using a first-principles, self-consistent, full-potential total energy method. Equilibrium lattice parameters, cohesive energies, density of states and formation energies of substitutional defects are calculated. Results of all these calculations show that in the C15 NbCr{sub 2} + V compounds, V atoms substitute Cr atoms only.

  1. Isolation of anteiso-C17, iso-C17, iso-C16, and iso-C15 bacillomycin D from Bacillus amyloliquefaciens SD-32 and their antifungal activities against plant pathogens.

    PubMed

    Tanaka, Keijitsu; Ishihara, Atsushi; Nakajima, Hiromitsu

    2014-02-19

    Two new cyclic lipopeptides (3 and 4) were isolated from the culture filtrate of Bacillus amyloliquefaciens strain SD-32, together with two known metabolites, iso-C15 and iso-C16 bacillomycin D (1 and 2). Spectroscopic and chemical analyses identified the structures of the new compounds 3 and 4 as anteiso-C17 bacillomycin D, cyclic (l-Asn-d-Tyr-d-Asn-l-Pro-l-Glu-d-Ser-l-Thr-3-amino-14-methylhexadecanoic acid) and iso-C17 bacillomycin D, cyclic (l-Asn-d-Tyr-d-Asn-l-Pro-l-Glu-d-Ser-l-Thr-3-amino-15-methylhexadecanoic acid), respectively. The absolute configuration of C-3 in the β-amino fatty acid was determined to be R on the basis of the CD spectrum of its dinitrophenyl-p-methoxyaniline derivative. The activities of compounds 1-4 were evaluated against 13 plant pathogens: the activities of anteiso- and iso-C17 bacillomycin D (3 and 4) were almost the same and stronger than those of iso-C15 and iso-C16 bacillomycin D (1 and 2); iso-C15 bacillomycin D (1) was weakest. Compounds 2-4 inhibited the growth of all fungi tested; however, Pythium aphanidermatum was not inhibited at all by any of the compounds. Furthermore, compounds 1-4 at concentrations of 80, 40, 30, and 30 μM, respectively, inhibited completely the Botrytis cinerea infection in cucumber leaf.

  2. 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...

  3. 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.

  4. 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…

  5. 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.

  6. 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.

  7. 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)

  8. 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

  9. Phase stability, elastic anisotropy and electronic structure of cubic MAl2 (M = Mg, Ca, Sr and Ba) Laves phases from first-principles calculations

    NASA Astrophysics Data System (ADS)

    Kong, Yuanyuan; Duan, Yonghua; Ma, Lishi; Li, Runyue

    2016-10-01

    By performing first-principles calculations within the generalized gradient approximation, the phase stability, elastic constant and anisotropy, and density of states of cubic C15-type MAl2 (M = Mg, Ca, Sr and Ba) Laves phases have been investigated. Optimized equilibrium lattice parameters and formation enthalpies agree well with the available experimental data. Elastic constants C ij have been evaluated, and these C15-type MAl2 Laves phases are mechanically stable due to the meeting of C ij to the mechanical stability criteria. Polycrystalline elastic moduli have been deduced from elastic constants by Voigt-Reuss-Hill approximation. Plastic properties were characterized via values of B/G, Poisson’s ratio ν and Cauchy pressure (C 12-C 44). The elastic anisotropy has been considered by several anisotropy indexes (A U , A Z , A shear and A comp), anisotropy of shear modulus, and 3D surface constructions of bulk and Young’s moduli. Additionally, the sound velocity anisotropy and Debye temperature were predicted. Finally, electronic structures were carried out to reveal the underlying phase stability mechanism of these Laves phases.

  10. 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.

  11. 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.

  12. The effect of pressure on the phase transition behavior of tridecane, pentadecane, and heptadecane: A Fourier transform infrared spectroscopy study

    NASA Astrophysics Data System (ADS)

    Yamashita, Motoi; Hirao, Atsushi; Kato, Minoru

    2011-04-01

    The effect of pressure on the phase transition behavior of tridecane (C13), pentadecane (C15), and heptadecane (C17) has been investigated up to 489, 220, and 387 MPa, respectively, using Fourier transform infrared spectroscopy at 25 °C. The transition between the high pressure ordered (HPO) and high pressure rotator (HPR) phases has been observed in the pressure ranges of 270-220, 106-95, and 152-181 MPa for C13, C15, and C17, respectively, and the transition between the HPR and liquid phases was observed in the pressure ranges of 171-112, 73-47, and 43-70 MPa for C13, C15, and C17, respectively. The P1+P3 band of the methylene rocking mode exhibits factor group splitting caused by intermolecular vibrational coupling. This was observed in both the HPO and HPR phases, while the P1+P3 band did not split in the liquid phase. The separation of the peaks in the P1+P3 band changed discontinuously at the HPO-HPR and HPR-liquid phase transitions, even though the separation is known to change continuously in the transition from the liquid to the high temperature rotator (HTR) phase. In the HPR phase, the ratio of the intensities of the higher and lower frequency components in the P1+P3 doublet is roughly unity independent of pressure, while it is known to be much less than unity in the HTR phase. The separation of the P1+P3 doublet in the HPR phase is found to be larger for longer alkanes. From the intensity ratio, a large proportion of alkane molecules is believed to participate in intermolecular vibrational coupling and possess herringbone-type short-range positional order in the HPR phase. Conversely, in the HTR phase only small proportion of alkane molecules participate in intermolecular vibrational coupling. From the pressure dependence of the separation of the doublet, intermolecular vibrational coupling and herringbone-type short-range positional order is considered to change discontinuously at the HPR-liquid phase transition, while they are reported to change

  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. Phase array calibration orthogonal phase sequence

    NASA Technical Reports Server (NTRS)

    Sorace, Ronald E. (Inventor); Reinhardt, Victor S. (Inventor); Chan, Clinton (Inventor)

    1999-01-01

    Methods and systems for calibrating an array antenna are described. The array antenna has a plurality of antenna elements each having a signal with a phase and an amplitude forming an array antenna signal. For calibration, the phase of each element signal is sequentially switched one at a time through four orthogonal phase states. At each orthogonal phase state, the power of the array antenna signal is measured. A phase and an amplitude error for each of the element signals is determined based on the power of the array antenna signal at each of the four orthogonal phase states. The phase and amplitude of each of the element signals is then adjusted by the corresponding phase and amplitude errors.

  15. Focus on Phase Electives.

    ERIC Educational Resources Information Center

    Jones, Victor H., Ed.

    1976-01-01

    In this thematic issue, articles focus on the use of phase electives in the English classroom. Discussions include "Death in the Classroom,""Soapbox Operas in the English Classroom,""Language and History in Phase-Elective Programs,""Phase Electives and the Problem of Composition," and "Phase Electives and College Preparation.""Phase Electives Are…

  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. High-throughput backbone resonance assignment of small 13C, 15N-labeled proteins by a triple-resonance experiment with four sequential connectivity pathways using chemical shift-dependent, apparent 1J ( 1H, 13C): HNCACB codedHAHB

    NASA Astrophysics Data System (ADS)

    Pegan, Scott; Kwiatkowski, Witek; Choe, Senyon; Riek, Roland

    2003-12-01

    The proposed three-dimensional triple-resonance experiment HNCACB codedHAHB correlates sequential 15N, 1H moieties via the chemical shifts of 13C α, 13C β, 1H α, and 1H β. The four sequential correlation pathways are achieved by the incorporation of the concept of chemical shift-coding [J. Biomol. NMR 25 (2003) 281] to the TROSY-HNCACB experiment. The monitored 1H α and 1H β chemical shifts are then coded in the line shape of the cross-peaks of 13C α, 13C β along the 13C dimension through an apparent residual scalar coupling, the size of which depends on the attached hydrogen chemical shift. The information of four sequential correlation pathways enables a rapid backbone assignment. The HNCACB codedHAHB experiment was applied to ˜85% labeled 13C, 15N-labeled amino-terminal fragment of Vaccinia virus DNA topoisomerase I comprising residues 1-77. After one day of measurement on a Bruker Avance 700 MHz spectrometer and 8 h of manual analysis of the spectrum 93% of the backbone assignment was achieved.

  18. Recoupling pulse sequences with constant phase increments

    NASA Astrophysics Data System (ADS)

    Khaneja, Navin; Kumar, Ashutosh

    2016-10-01

    The paper studies a family of recoupling pulse sequences in magic angle spinning (MAS) solid state NMR, that are characterized by constant phase increments at regular intervals. These pulse sequences can be employed for both homonuclear and heteronuclear recoupling experiments and are robust to dispersion in chemical shifts and rf-inhomogeneity. The homonuclear pulse sequence consists of a building block (2 π) ϕp , where ϕp =p (n - 1) π/n, where n is number of blocks in a rotor period and p = 0, 1, 2, … . The pulse sequence repeats itself every rotor period when n is odd and every two rotor period when n is even. The heteronuclear recoupling pulse sequence consists of a building block (2 π) ϕ1p and (2 π) ϕ2p on channel I and S, where ϕ1p = p (2 n - 3) π/2 n, ϕ2p = p (2 n - 1) π/2 n and n is number of blocks in a rotor period. The recoupling pulse sequences mix the z magnetization. Experimental quantification of this method is shown for 13Cα -13CO , homonuclear recoupling in a sample of Glycine and 15N -13Cα , heteronuclear recoupling in Alanine. Application of this method is demonstrated on a sample of tripeptide N-formyl-[U-13C ,15N ]- Met-Leu-Phe-OH (MLF).

  19. 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

  20. 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

  1. 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

  2. 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.

  3. 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.

  4. Wideband Linear Phase Modulator

    NASA Technical Reports Server (NTRS)

    Mysoor, Narayan R.; Mueller, Robert O.

    1994-01-01

    Phase modulator for transmission in X band provides large phase deviation that remains nearly linear with voltage over relatively wide range. Operates with low loss over wide frequency band and with stable characteristics over wide temperature range. Phase modulator contains two varactor-diode phase shifters coupled via circulators. Separate drive circuit applies modulating voltages to varactor diodes. Modulation voltages vary in accordance with input to drive circuit.

  5. 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)

  6. 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

  7. The phase 2 NRA

    NASA Technical Reports Server (NTRS)

    Chipman, Eric

    1992-01-01

    We present points of special interest to potential proposers for the Compton Observatory Phase 2 Guest Investigator (GI) program. A general summary of some of the most important details of the phase 2 NASA Research Announcement (NRA) is followed by an enumeration of the modes of participation and proposal types available to GI proposers. Finally, the method which is planned for the selection of the Phase 2 Guest Investigators in parallel with the development of a preliminary Phase 2 observing timeline is outlined. The ways in which the selection of targets by GI's could be affected by the Phase 2 timeline development procedure is described.

  8. 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.

  9. 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)

  10. Quantum-phase synchronization

    NASA Astrophysics Data System (ADS)

    Fiderer, Lukas J.; Kuś, Marek; Braun, Daniel

    2016-09-01

    We study mechanisms that allow one to synchronize the quantum phase of two qubits relative to a fixed basis. Starting from one qubit in a fixed reference state and the other in an unknown state, we find that, contrary to the impossibility of perfect quantum cloning, the quantum phase can be synchronized perfectly through a joined unitary operation. When both qubits are initially in a pure unknown state, perfect quantum-phase synchronization through unitary operations becomes impossible. In this situation we determine the maximum average quantum-phase synchronization fidelity and the distribution of relative phases and fidelities, and we identify optimal quantum circuits that achieve this maximum fidelity. A subset of these optimal quantum circuits enable perfect quantum-phase synchronization for a class of unknown initial states restricted to the equatorial plane of the Bloch sphere.

  11. Active aperture phased arrays

    NASA Astrophysics Data System (ADS)

    Shenoy, R. P.

    1989-04-01

    Developments towards the realization of active aperture phased arrays are reviewed. The technology and cost aspects of the power amplifier and phase shifter subsystems are discussed. Consideration is given to research concerning T/R modules, MESFETs, side lobe control, beam steering, optical control techniques, and printed circuit antennas. Methods for configuring the array are examined, focusing on the tile and brick configurations. It is found that there is no technological impediment for introducing active aperture phased arrays.

  12. Cosmological phase transitions

    SciTech Connect

    Kolb, E.W. |

    1993-10-01

    If modern ideas about the role of spontaneous symmetry breaking in fundamental physics are correct, then the Universe should have undergone a series of phase transitions early in its history. The study of cosmological phase transitions has become an important aspect of early-Universe cosmology. In this lecture I review some very recent work on three aspects of phase transitions: the electroweak transition, texture, and axions.

  13. 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.

  14. 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.

  15. Phase-Conjugated Fluorescence

    DTIC Science & Technology

    1991-01-01

    reverse if necessary and identify by block number)FIELD GROUP SUB-GROUP PHASE-CONJUGATED FLUORESCENCE EMITTED POWER FOUR -WAVE MIXING THREE CONTRIBUTIONS...atom near a phase conjugator (PC) based on four -wave mixing is studied from first principles. The MaxwellLeisenberg equations are solved for the...Fronczak Hall State University of New York at Buffalo Buffalo, New York 14260 Fluorescent emission by an atom near a phase conjugator (PC) based on four -wave

  16. 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.

  17. Instantaneous phase shifting deflectometry.

    PubMed

    Trumper, Isaac; Choi, Heejoo; Kim, Dae Wook

    2016-11-28

    An instantaneous phase shifting deflectometry measurement method is presented and implemented by measuring a time varying deformable mirror with an iPhone ® 6. The instantaneous method is based on multiplexing phase shifted fringe patterns with color, and decomposing them in x and y using Fourier techniques. Along with experimental data showing the capabilities of the instantaneous deflectometry system, a quantitative comparison with the Fourier transform profilometry method, which is a distinct phase measuring method from the phase shifting approach, is presented. Sources of error, nonlinear color-multiplexing induced error correction, and hardware limitations are discussed.

  18. Nonlocal chaotic phase synchronization

    NASA Astrophysics Data System (ADS)

    Zhan, Meng; Zheng, Zhi-Gang; Hu, Gang; Peng, Xi-Hong

    2000-09-01

    A novel synchronization behavior, nonlocal chaotic phase synchronization, is investigated. For two coupled Rossler oscillators with only one forced by an injected periodic signal, the phase of the unforced oscillator can be locked to the phase of the periodic signal while the forced one is well unlocked by the signal; in a chain of coupled chaotic oscillators with nearest coupling, the phase of an oscillator (or a cluster) can be locked to another nonneighbor one. Moreover, the mechanism underlying the transition to nonlocal synchronization is discussed in detail.

  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 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

  1. 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...

  2. 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)

  3. 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.

  4. A Phase Odyssey

    SciTech Connect

    Nugent, K.A.; Paganin, D.; Gureyev, T.E.

    2009-01-06

    We are introduced to the effects of phase from the earliest days of our childhood, from the nursery rhyme above (or its less verbose for 'Twinkle, Twinkle Little Star') to the shimmer over a hot road and the network of bright lines at the bottom of a swimming pool. These are all manifestations of phase. And there are many more.

  5. 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.)

  6. 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.

  7. Phase singularity diffusion.

    PubMed

    Cheng, Xiaojun; Lockerman, Yitzchak; Genack, Azriel Z

    2014-06-01

    We follow the trajectories of phase singularities at nulls of intensity in the speckle pattern of waves transmitted through random media as the frequency of the incident radiation is scanned in microwave experiments and numerical simulations. Phase singularities are observed to diffuse with a linear increase of the square displacement 〈R2〉 with frequency shift. The product of the diffusion coefficient of phase singularities in the transmitted speckle pattern and the photon diffusion coefficient through the random medium is proportional to the square of the effective sample length. This provides the photon diffusion coefficient and a method for characterizing the motion of dynamic material systems.

  8. 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.

  9. Optical fiber phase discriminator.

    PubMed

    Danielson, B L

    1978-11-15

    Phase discriminators are devices widely used at rf and microwave frequencies to convert phase, or frequency, changes to amplitude changes. They find widespread use in generating audio feedback signals for frequency stabilization of oscillators and in angle demodulation applications. This paper demonstrates that similar devices, with similar functions, can be constructed in the visible region using optical fibers as delay-line elements. The operating principles of an optical-fiber delay-line phase discriminator are discussed. The sensitivity is shown to be proportional to the fiber propagation-delay time. A device working at 0.6328 microm is described and compared with predictions.

  10. Sliding Luttinger liquid phases

    NASA Astrophysics Data System (ADS)

    Mukhopadhyay, Ranjan; Kane, C. L.; Lubensky, T. C.

    2001-07-01

    We study systems of coupled spin-gapped and gapless Luttinger liquids. First, we establish the existence of a sliding Luttinger liquid phase for a system of weakly coupled parallel quantum wires, with and without disorder. It is shown that the coupling can stabilize a Luttinger liquid phase in the presence of disorder. We then extend our analysis to a system of crossed Luttinger liquids and establish the stability of a non-Fermi-liquid state: the crossed sliding Luttinger liquid phase. In this phase the system exhibits a finite-temperature, long-wavelength, isotropic electric conductivity that diverges as a power law in temperature T as T-->0. This two-dimensional system has many properties of a true isotropic Luttinger liquid, though at zero temperature it becomes anisotropic. An extension of this model to a three-dimensional stack exhibits a much higher in-plane conductivity than the conductivity in a perpendicular direction.

  11. 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.

  12. Dense Nonaqueous Phase Liquids

    EPA Pesticide Factsheets

    This issue paper is a literature evaluation focusing on DNAPLs and provides an overview from a conceptual fate and transport point of view of DNAPL phase distribution, monitoring, site characterization, remediation, and modeling.

  13. Wide deviation phase modulator

    NASA Technical Reports Server (NTRS)

    Couch, R. H.; Hearn, C. P.; Wilson, L. R.

    1974-01-01

    Modulator produces phase-modulated waveform having high modulating linearity. Technique is inherently wideband with respect to carrier frequency and can operate over decade carrier frequency range without adjustments. Circuit performance is both mathematically predictable and highly reproducible.

  14. 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.

  15. 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)

  16. 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.

  17. Quantum Phase Transitions

    DTIC Science & Technology

    2011-05-01

    Park, NC 27709-2211 15. SUBJECT TERMS Quantum Thoery Phase transitions Subir Sachdev Harvard University Office of Sponsored Research 1350...magnetism, and solvable models obtained from string theory. After introducing the basic theory, it moves on to a detailed description of the canonical...students and researchers in condensed matter physics and particle and string theory. Print | Close Quantum Phase Transitions 2nd Edition Subir Sachdev

  18. Phases of the Moon

    NASA Astrophysics Data System (ADS)

    Murdin, P.

    2000-11-01

    The various aspects that the Moon presents to observers on the Earth as the proportion of its sunlit side which is visible changes in the course of its orbit around the Earth. There are four principle phases: new moon, first quarter, full moon and last quarter. One complete cycle of phases is termed a lunation, and is completed in just over 29½ days, the Moon's synodic period....

  19. Bigradient Phase Referencing

    NASA Astrophysics Data System (ADS)

    Doi, Akihiro; Fujisawa, Kenta; Habe, Asao; Honma, Mareki; Kawaguchi, Noriyuki; Kobayashi, Hideyuki; Murata, Yasuhiro; Omodaka, Toshihiro; Sudou, Hiroshi; Takaba, Hiroshi

    2006-08-01

    We propose bigradient phase referencing (BPR), a new radio-observation technique, and report on its performance using the Japanese very-long-baseline-interferometry network (JVN). In this method, a weak source is detected by phase-referencing using a primary calibrator, in order to play a role as a secondary calibrator for phase-referencing to a weak target. We will be given the opportunity to select a calibrator from lots of milli-Jansky sources, one of which may be located at a position closer to the target. With such a smaller separation, high-quality phase-referencing can be achieved. A subsequent more-sophisticated calibration can relocate the array's focus to a hypothetical point much closer to the target; a higher quality of phase referencing is available. Our demonstrative observations with strong radio sources have proved the capabilities of the BPR in terms of the image dynamic ranges and astrometric reproducibility. The image dynamic range on a target has been improved by a factor of about six compared to that of normal phase-referencing; the resultant position difference of the target's emission between two epochs was only 62±50 microarcsecond, even with less than 2300-km baselines at 8.4GHz and fast-switching between a target-calibrator pair separated by a 2.°1.

  20. 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.

  1. Phased array ghost elimination

    PubMed Central

    Kellman, Peter; McVeigh, Elliot R.

    2007-01-01

    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

  2. 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.

  3. Introduction to phasing.

    PubMed

    Taylor, Garry L

    2010-04-01

    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 A 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 the structure

  4. 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.

  5. Magnetic properties and large magnetocaloric effect in Laves phase metallic compound

    NASA Astrophysics Data System (ADS)

    Gao, Tian; Qi, Ningning; Zhang, Yufeng; Zhou, Tao

    2014-12-01

    We investigated the magnetic properties and magnetocaloric effect of C15 Laves phase TbMn1.6Fe0.4 by magnetization and heat capacity measurements. A sharp second-order magnetic Tb-Tb ordering transition at Curie temperature TC ~ 120 K and a short-range Fe-Fe ordering transition at ~230 K are observed. Around TC, the compound shows a large magnetocaloric effect with no obvious thermal and magnetic hysteresis loss. The maximum value of magnetic entropy change reaches 8.72 J kg-1 K-1 for a magnetic field change ΔH = 7 T over a wide temperature range. The obtained relative cooling power reaches 184, 560, and 803 J kg-1 for ΔH = 2, 5 and 7 T, respectively. Large reversible magnetocaloric effect and the wide operating temperature range indicate that TbMn1.6Fe0.4 could be a promising candidate for magnetic refrigeration.

  6. Progress in ferrite phase shifters

    NASA Astrophysics Data System (ADS)

    Boyd, C. R., Jr.

    1983-10-01

    Advances in the technology of reciprocal ferrite phase shifters are outlined. Nonlatching rotary-field phase shifters have been produced with enhanced phase accuracy and modest control power. A significant quantity of dual-mode latching units has been built at 35 GHz, with good results. Both types of phase shifter can be adapted to perform other functions in addition to phase shifting. Examples of phase shifters that perform duplexing and polarization switching functions are given.

  7. 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.

  8. 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.

  9. Phases of unstable conifolds

    SciTech Connect

    Narayan, K.

    2007-03-15

    We explore the phase structure induced by closed string tachyon condensation of toric nonsupersymmetric conifold-like singularities described by an integral charge matrix Q=(n{sub 1}n{sub 2}-n{sub 3}-n{sub 4}), n{sub i}>0, iQ{sub i}{ne}0, initiated by Narayan [J. High Energy Phys. 03 (2006) 036]. Using gauged linear sigma model renormalization group flows and toric geometry techniques, we see a cascadelike phase structure containing decays to lower order conifold-like singularities, including, in particular, the supersymmetric conifold and the Y{sup pq} spaces. This structure is consistent with the Type II GSO projection obtained previously for these singularities. Transitions between the various phases of these geometries include flips and flops.

  10. Interferometric phase velocity measurements

    NASA Technical Reports Server (NTRS)

    Kintner, P. M.; Labelle, J.; Kelley, M. C.; Cahill, L. J., Jr.; Moore, T.; Arnoldy, R.

    1984-01-01

    Phase velocities of plasma waves near the lower hybrid frequency were measured with an interferometer composed of two spatially separated electron-density probes. The plasma waves were produced in the F-region ionosphere by an argon ion beam. By calculating the normalized cross spectrum of the plasma waves a coherency of .98 was estimated along with a maximum phase difference of pi/3 radians between the two probes. This implies that the wavelength was 6 meters compared to an O(+) gyroradius of 3.8 meters, and that the phase velocity was 45 km/sec compared to an ion-beam velocity of 12.4 km/sec. These numbers compare favorably with recent predictions of a nonresonant mode produced by a dense ion beam.

  11. 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.

  12. 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.

  13. 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 .

  14. 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.

  15. 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.

  16. 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).

  17. Noise and Phase Transitions

    NASA Astrophysics Data System (ADS)

    Chen, Zhi; Yu, Clare C.

    2006-03-01

    Noise is present in many physical systems and is often viewed as a nuisance. Yet it can also be a probe of microscopic fluctuations. There have been indications recently that the noise in the resistivity increases in the vicinity of the metal-insulator transition. But what are the characteristics of the noise associated with well-understood first and second order phase transitions? It is well known that critical fluctuations are associated with second order phase transitions, but do these fluctuations lead to enhanced noise? We have addressed these questions using Monte Carlo simulations to study the noise in the 2D Ising model which undergoes a second order phase transition, and in the 5-state Potts model which undergoes a first order phase transition. We monitor these systems as the temperature drops below the critical temperature. At each temperature, after equilibration is established, we obtain the time series of quantities characterizing the properties of the system, i.e., the energy and magnetization per site. We apply different methods, such as the noise power spectrum, the Detrended Fluctuation Analysis (DFA) and the second spectrum of the noise, to analyze the fluctuations in these quantities.

  18. Phase-contrast radiography.

    PubMed

    Gao, D; Pogany, A; Stevenson, A W; Wilkins, S W

    1998-01-01

    For the past 100 years, the paradigm for radiography has been premised on absorption as the sole means of contrast formation and on ray optics as the basis for image interpretation. A new conceptual approach to radiography has been developed that includes phase (ie, refractive) contrast and requires wave optics for proper treatment. This new approach greatly increases the amount of information that can be obtained with radiographic techniques and is particularly well suited to the imaging of soft tissue and of very small features in biologic samples. A key feature of the present technique of phase-contrast radiography is the use of a microfocus x-ray source about an order of magnitude (< or = 20 microm) smaller than that used in conventional radiography. Phase-contrast radiography offers a number of improvements over conventional radiography in a clinical setting, especially in soft-tissue imaging. These improvements include increased contrast resulting in improved visualization of anatomic detail, reduced absorbed dose to the patient, inherent image magnification and high spatial resolution, use of harder x rays, and relative ease of implementation. More technologically advanced detectors are currently being developed and commercialized, which will help fully realize the considerable potential of phase-contrast imaging.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. Linear Phase Modulator

    NASA Technical Reports Server (NTRS)

    Hesse, R. H.

    1986-01-01

    Circuit suppresses AM component while providing matched input impedance. Phase modulation uses reflective properties of series resonant tank to reflect all of signal except for small amount in unloaded Q of coils and varactor diode. Circuit used in payload integrator of Space Shuttle S-band communications and tracking equipment, has applications in other communications and tracking equipment.

  5. MAD phasing with krypton.

    PubMed

    Cohen, A; Ellis, P; Kresge, N; Soltis, S M

    2001-02-01

    Experiments demonstrating the feasibility of Kr-edge MAD on frozen crystals as a routine method for structure determination are reported. Approximately 50% of protein crystals can be successfully derivatized by pressurization with the noble gases xenon or krypton. While Xe has produced many useful derivatives for MIR phasing over the last several years, the Xe edges (K edge = 34.6 keV, L(I) = 5.5 keV) are not easily accessible for MAD studies. As the Kr K edge (14.3 keV) is accessible on most MAD beamlines, Kr derivatization provides the additional opportunity to conduct a MAD experiment and obtain phases using only a single crystal. This paper describes the phasing of two proteins using Kr MAD: the 17 kDa Fe protein myoglobin (Mb) from sperm whale (Physeter catodon) and an 18 kDa protein (SP18) from green abalone (Haliotis fulgens). Three-wavelength data were collected at SSRL beamline 9-2 from crystals of Mb and SP18 incubated in 2.76 MPa of Kr gas for 2 min, depressurized and then flash-frozen in a stream of nitrogen gas at 100 K. MAD phases were calculated using the program SHARP and the resulting density improved with wARP. The final maps for both Mb and SP18 were of excellent quality.

  6. 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.

  7. 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…

  8. 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…

  9. 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.

  10. Simultaneous elimination of dissolved and dispersed pollutants from cutting oil wastes using two aqueous phase extraction methods.

    PubMed

    Talbi, Z; Haddou, B; Bouberka, Z; Derriche, Z

    2009-04-30

    Oily wastewater experimental study has been accomplished using two aqueous phases extraction methods on the basis of phase separation properties of non-ionic surfactants above the so-called cloud point curve and the solubilization phenomena of coacervate micelles (surfactant rich phase). Two commercial ethoxylate fatty alcohol surfactants (Oxo-C(10)E(3), Oxo-C(15)E(7)) were employed to treat three kinds of cutting oil wastewater, in order to define the conditions promoting cutting oils emulsions destabilization and cloud point extraction possesses simultaneously. Before extraction test, the phase diagrams of binary water/surfactants systems were drawn and the effect of some cutting oil additives on water-surfactant systems was, therefore studied. The results of oily wastewater extraction with respect to wt.% surfactant and temperature were expressed in terms of chemical oxygen demand (COD) of the dilute phase before and after extraction, residual chemical oxygen demand (COD(R)), residual concentrations of surfactant in the dilute phase (X(t,w)) converted to chemical oxygen demand (COD(T)) and the volume fraction of coacervate (phi(c)) at the equilibrium. The results obtained for each parameter which were also represented on three dimensional diagrams using an empirical smoothing method were in agreement with the experimental ones, where the COD(R) was reduced from 55 to 1.1 g O(2)l(-1).

  11. Digital Phase-Locked Loop With Phase And Frequency Feedback

    NASA Technical Reports Server (NTRS)

    Thomas, J. Brooks

    1991-01-01

    Advanced design for digital phase-lock loop (DPLL) allows loop gains higher than those used in other designs. Divided into two major components: counterrotation processor and tracking processor. Notable features include use of both phase and rate-of-change-of-phase feedback instead of frequency feedback alone, normalized sine phase extractor, improved method for extracting measured phase, and improved method for "compressing" output rate.

  12. Large phase-by-phase modulations in atomic interfaces.

    PubMed

    Artoni, M; Zavatta, A

    2015-09-11

    Phase-resonant closed-loop optical transitions can be engineered to achieve broadly tunable light phase shifts. Such a novel phase-by-phase control mechanism does not require a cavity and is illustrated here for an atomic interface where a classical light pulse undergoes radian level phase modulations all-optically controllable over a few micron scale. It works even at low intensities and hence may be relevant to new applications of all-optical weak-light signal processing.

  13. 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.

  14. Phase switching in population cycles

    PubMed Central

    Henson, S. M.; Cushing, J. M.; Costantino, R. F.; Dennis, B.; Desharnais, R. A.

    1998-01-01

    Oscillatory populations may exhibit a phase change in which, for example, a high–low periodic pattern switches to a low–high pattern. We propose that phase shifts correspond to stochastic jumps between basins of attraction in an appropriate phase space which associates the different phases of a periodic cycle with distinct attractors. This mechanism accounts for two-cycle phase shifts and the occurrence of asynchronous replicates in experimental cultures of Tribolium.

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

    PubMed

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

    2014-09-14

    We report a Phase-Alternating R-Symmetry (PARS) dipolar recoupling scheme for accurate measurement of heteronuclear (1)H-X (X = (13)C, (15)N, (31)P, 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 (1)H CSA interaction persists and thereby introduces considerable errors in the dipolar measurements. In PARS, phase-shifted RN symmetry pulse blocks applied on the (1)H spins combined with π pulses applied on the X spins at the end of each RN block efficiently suppress the effect from (1)H chemical shift anisotropy, while keeping the (1)H-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, [(15)N]-N-acetyl-valine and [U-(13)C,(15)N]-N-formyl-Met-Leu-Phe tripeptide. The application of PARS for site-resolved measurement of accurate (1)H-(15)N dipolar couplings in the context of 3D experiments is presented on U-(13)C,(15)N-enriched dynein light chain protein LC8.

  16. 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.

  17. Multipulse phase resetting curves

    NASA Astrophysics Data System (ADS)

    Krishnan, Giri P.; Bazhenov, Maxim; Pikovsky, Arkady

    2013-10-01

    In this paper, we introduce and study systematically, in terms of phase response curves, the effect of dual-pulse excitation on the dynamics of an autonomous oscillator. Specifically, we test the deviations from linear summation of phase advances resulting from two small perturbations. We analytically derive a correction term, which generally appears for oscillators whose intrinsic dimensionality is >1. The nonlinear correction term is found to be proportional to the square of the perturbation. We demonstrate this effect in the Stuart-Landau model and in various higher dimensional neuronal models. This deviation from the superposition principle needs to be taken into account in studies of networks of pulse-coupled oscillators. Further, this deviation could be used in the verification of oscillator models via a dual-pulse excitation.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. Nucleosome phasing - new insights

    NASA Astrophysics Data System (ADS)

    Chereji, Razvan

    2014-03-01

    Eukaryotic genomes are organized into arrays of nucleosomes, in which stretches of 147 base-pairs of DNA are wrapped around octameric histones. Recently, a new method of mapping nucleosome positions was developed, which gives a much higher accuracy than the typical MNase-seq method. I present a statistical mechanics model which is able to reproduce the high-resolution nucleosome positioning data. I show that the DNA sequence is not the main cause of the nucleosome phasing which is observed genome-wide, and I present the major nucleosome phasing elements. The statistical mechanics framework is general enough to be useful in explaining different experimental observations, and I present a few results of this model.

  7. 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.

  8. Phases and phase transitions in disordered quantum systems

    NASA Astrophysics Data System (ADS)

    Vojta, Thomas

    2013-08-01

    These lecture notes give a pedagogical introduction to phase transitions in disordered quantum systems and to the exotic Griffiths phases induced in their vicinity. We first review some fundamental concepts in the physics of phase transitions. We then derive criteria governing under what conditions spatial disorder or randomness can change the properties of a phase transition. After introducing the strong-disorder renormalization group method, we discuss in detail some of the exotic phenomena arising at phase transitions in disordered quantum systems. These include infinite-randomness criticality, rare regions and quantum Griffiths singularities, as well as the smearing of phase transitions. We also present a number of experimental examples.

  9. Solid phase extraction membrane

    DOEpatents

    Carlson, Kurt C [Nashville, TN; Langer, Roger L [Hudson, WI

    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.

  10. Phase Conjugate Optics.

    DTIC Science & Technology

    1982-11-01

    multimode fibers. We have developed a detailed model of the photorefractive effect which will be used as a basis for comparing photorefractive materials...of our system. The preliminary results indicate that a resolution of 5 lines/mm was obtained ( compared with a resolution without the fiber of "u20...for comparing photorefractive materials for nonlinear phase conjugation. Preliminary results of four materials surveyed indicate that KNbO3 and BaTiO3

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. Viking Phase III

    NASA Technical Reports Server (NTRS)

    1978-01-01

    VIKING PHASE III - With the incredible success of the Viking missions on Mars, mission operations have progressed though a series of phases - each being funded as mission success dictated its potential. The Viking Primary Mission phase was concluded in November, 1976, when the reins were passed on to the second phase - the Viking Extended Mission. The Extended Mission successfully carried spacecraft operations through the desired period of time needed to provided a profile of a full Martian year, but would have fallen a little short of connecting and overlapping a full Martian year of Viking operations which scientists desired as a means of determining the degree of duplicity in the red planet's seasons - at least for the summer period. Without this continuation of spacecraft data acquisitions to and beyond the seasonal points when the spacecraft actually began their Mars observations, there would be no way of knowing whether the changing environmental values - such as temperatures and winds atmospheric dynamics and water vapor, surface thermal dynamics, etc. - would match up with those acquired as the spacecraft began investigations during the summer and fall of 1976. This same broad interest can be specifically pursued at the surface - where hundreds of rocks, soil drifts and other features have become extremely familiar during long-term analysis. This picture was acquired on the 690th Martian day of Lander 1 operations - 4009th picture sequence commanded of the two Viking Landers. As such, it became the first picture acquired as the third phase of Viking operations got under way - the Viking Continuation Mission. Between the start of the Continuation Mission in April, 1978, until spacecraft operations are concluded in November, the landers will acquire an additional 200 pictures. These will be used to monitor the two landscaped for the surface changes. All four cameras, two on Lander 1 and two on Lander 2, continue to operate perfectly. Both landers will also

  16. Helical phases in superconductors

    NASA Astrophysics Data System (ADS)

    Sandhu, Raminder P. Kaur

    In conventional superconductors, the Cooper pairs are formed from quasiparticles with opposite momentum and spins because of the degeneracy of the quasiparticles under time reversal and inversion. The absence of any of these symmetries will have pronounced effects on superconducting states. Time reversal symmetry can be broken in the presence of magnetic impurities or by the application of a magnetic field. Similarly, the dislocation of crystal ions from their higher symmetric positions can cause broken inversion symmetry. We studied the effects of broken time reversal and inversion symmetries on unconventional superconductors, such as high temperature cuprates, Sr2RuO 4, and CePt3Si. In the cuprates, the superconducting state exists near the antiferromagnetic order. Sr2RuO4 and CePt3Si do not have spatial inversion, and the superconducting states coexist with magnetic order. In cuprates, the broken time reversal symmetry has been reported in the pseudogap phase which will effect the d-wave superconducting state of underdoped regime. On the basis of symmetry analysis we found that a mixture of spin-singlet and -triplet state, d+ip, which is shown to give rise to a helical superconducting phase. Consequences of this d+ip state on Josephson experiments are also discussed. Sr2RuO 4 is known to be another broken time reversal superconductor with spin triplet superconductivity. The widely believed superconducting state, the chiral p wave state, has been extensively studied through Ginzburg Landau theory, but the predictions for this state contradict some experimental observations like anisotropy in the upper critical field, and the existence of a second vortex state. We have formalize quasiclassical theory to find the origin of these contradictions, and also extended the theory to study other possible super-conducting states. Surprisingly, we find that a superconducting state corresponding to freely rotating in-plane d-vector explains the existing experimental results

  17. 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.

  18. 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.

  19. Temperature- and pressure-induced structural transitions in rare-earth-deficient ? (R = Y, Sm, Gd, Tb) Laves phases

    NASA Astrophysics Data System (ADS)

    Gratz, E.; Kottar, A.; Lindbaum, A.; Mantler, M.; Latroche, M.; Paul-Boncour, V.; Acet, M.; Barner, Cl; Holzapfel, W. B.; Pacheco, V.; Yvon, K.

    1996-10-01

    Electrical resistivity, thermal expansion, and temperature-dependent x-ray diffraction measurements on 0953-8984/8/43/026/img14 compounds give mutually consistent evidence for structural phase transitions at 740 K, 550 K, 600 K, and 450 K respectively for R = Y, Sm, Gd, Tb; 0 < x < 0.05. Arguments are given as to why most of the rare-earth - nickel compounds with the 1:2 ratio do not crystallize in the simple cubic Laves phase (C15 type) but show a superstructure of the cubic Laves phase at room temperature and at ambient pressure. This superstructure with the space group 0953-8984/8/43/026/img15 and a doubled cell parameter is characterized by ordered vacancies on the R sites. It is shown that the observed structural instabilities result in transitions to the cubic Laves phase (space group 0953-8984/8/43/026/img16), however with disordered vacancies at high temperatures. High-pressure x-ray powder diffraction experiments show that the phase transition in 0953-8984/8/43/026/img17 shifts down to room temperature for a pressure of 27 GPa.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. Solid phases of tenoxicam.

    PubMed

    Cantera, Rodrigo G; Leza, María G; Bachiller, Carmen M

    2002-10-01

    In this report we describe the preparation and characterization of four polymorphic forms of tenoxicam; they are, three 1:1 stoichiometric solvates with acetonitrile, dioxane, and N,N-dimethylformamide, and an amorphous phase obtained by recrystallization in various solvents. Polymorph IV and solvates with dioxane and N,N-dimethylformamide are reported for the first time in this paper. In addition, three solvates were crystallized in acetone, ethyl acetate, and isopropyl alcohol. These solid forms were characterized by X-ray powder diffraction, differential scanning calorimetry, infrared spectroscopy, thermogravimetry, optical microscopy, and elemental analysis. Solid-state properties, intrinsic dissolution rate, and dissolution kinetics from formulated tablets are also provided.

  5. 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

  6. 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.

  7. 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.

  8. 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).

  9. Calculation of Ceramic Phase Diagrams

    DTIC Science & Technology

    1979-11-30

    Parameters were derived covering the liquid, spinel , periclase, corundum alpha and beta. DD IJAN73 1413 EDITIOW OF I NOV4SS IS OSSOLETE (/Ai/Ec-;/ 5 - -rZ7 77...Lattice Stability, Solution and Compound Phase Parameters were derived covering the liquid, spinel , periclase, corundum alpha and beta quartz, crystobalite...and compound phase parameters for the liquid, spinel , corundum and periclase phases can be employed to calculate phase equilibria activity, vapor

  10. Multiple phases of protien gels

    NASA Astrophysics Data System (ADS)

    Annaka, Masahiko; Tanaka, Toyoichi

    1994-03-01

    A multiple phase transition was observed in gels made by covalently cross-linking proteins in either native or denatured state. The enzymatic activity of the gels prepared from native α-chymotrypsin was determined for each of the multiple phases. The reversibility of the swelling degrees and the enzymatic reaction rates upon phase transition suggests that the protein is at a free energy minimum and thus in a phase.

  11. 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.

  12. 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.

  13. 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.

  14. Phase down of amalgam

    PubMed Central

    AL-Rabab’ah, Mohammad A.; Bustani, Mohammad A.; Khraisat, Ameen S.; Sawair, Faleh A.

    2016-01-01

    Objectives To assess the knowledge of Jordanian dentists toward phase down of dental amalgam as recommended by the Minamata Convention, and their training and competency in placing posterior composites. Methods This study was conducted through structured questionnaire interviews with randomly selected cohort of dentists in Jordan between March 2015 and June 2015. Out of 230 dentists who were invited, 196 (85.2%) agreed to participate. Dentists were asked if they know about the Minamata Convention. They were also asked about their training in placement of posterior composite. Results Out of the 196 interviewed, only 13.8% know about Minamata Convention and 17% had an undergraduate training in favor of placing composites in posterior teeth. Approximately 50% of those dentists were not trained in using rubber dam when placing posterior composites, while only 38.3% had training in sectional matrix placement. Undergraduate training did not influence (p=0.00) the dentists’ decision to remove old amalgam based on patient’s demands. Only 28.1% were of the opinion of discontinuing the use of amalgam due to its alleged health and environmental hazards. There was no general agreement on the type of composite, liner, and bonding strategy when placing posterior composites. Conclusion Dentists are not well informed on the Minamata Convention and the phase down of amalgam. Training in posterior composite placement should be given more room in undergraduate curriculum and continuous dental education. PMID:27874155

  15. Three phase power factor controller

    NASA Technical Reports Server (NTRS)

    Nola, F. J. (Inventor)

    1984-01-01

    A power control circuit for a three phase induction motor is described. Power factors for the three phases are summed to provide a control signal, and this control signal is particularly filtered and then employed to control the duty cycle of each phase of input power to the motor.

  16. Three phase power factor controller

    NASA Technical Reports Server (NTRS)

    Nola, F. J. (Inventor)

    1980-01-01

    A power control circuit for a three phase induction motor is described. The power factors for the three phases are summed to provide a control signal. This control signal is particularly filtered and then employed to control the duty cycle of each phase of input power to the motor.

  17. 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.

  18. Phase contrast MR angiography techniques.

    PubMed

    Dumoulin, C L

    1995-08-01

    Phase contrast MR methods encode information from macroscopic motion into the phase of the MR signal. Phase contrast methods can be applied with small and large fields-of-view, can give quantitative measures of velocity, and provide excellent suppression of signals from stationary tissue. Unlike time-of-flight methods, phase contrast methods directly measure flow and thus are not hindered by the artifactual appearance of tissue having short T1. Phase contrast angiograms can be two-dimensional (thin slice or projectile), three-dimensional, and/or time resolved and have applications throughout the body.

  19. 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.

  20. Information encryption in phase space.

    PubMed

    Liu, Jun; Xu, Xiaobin; Wu, Quanying; Sheridan, John T; Situ, Guohai

    2015-03-15

    In this Letter, we propose an information encryption technique based on the theory of phase-space optics. We show that encoding the plaintext in phase space provides a higher level of security: first, the key-space is significantly enlarged. Second, it is immune to various known-plaintext (cyphertext) attacks to which the double-random phase encryption (DRPE) is vulnerable. Third, the bilinearity of phase-space distributions offers additional security. Theoretical analysis and numerical calculation results show that the proposed technique has significantly different responses to errors added to the cypheretext and the two phase keys in comparison to the classical DRPE.

  1. 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.

  2. Helical Nanofilament Phases

    SciTech Connect

    L Hough; H Jung; D Kruerke; M Heberling; M Nakata; C Jones; D Chen; D Link; N Clark; et al.

    2011-12-31

    In the formation of chiral crystals, the tendency for twist in the orientation of neighboring molecules is incompatible with ordering into a lattice: Twist is expelled from planar layers at the expense of local strain. We report the ordered state of a neat material in which a local chiral structure is expressed as twisted layers, a state made possible by spatial limitation of layering to a periodic array of nanoscale filaments. Although made of achiral molecules, the layers in these filaments are twisted and rigorously homochiral - a broken symmetry. The precise structural definition achieved in filament self-assembly enables collective organization into arrays in which an additional broken symmetry - the appearance of macroscopic coherence of the filament twist-produces a liquid crystal phase of helically precessing layers.

  3. Friction and Phase Synchronization

    NASA Astrophysics Data System (ADS)

    Braiman, Y.; Protopopescu, V.; Family, F.; Hentschel, H. G. E.

    2000-03-01

    Spatiotemporal fluctuations in small discrete nonlinear arrays affect the dynamics of the center of mass. We derive the equations describing the dynamics of the center of mass and the spatial fluctuations for each coherent mode of the array. Analysis of these equations indicates that depending on array stiffness, size, and the external forcing - quantized jumps occur in the minimum friction (maximum velocity) of the array. We propose an analytical formalism to determine the occurrences of these jumps. We present numerical evidence indicating that phase synchronization is related to the frictional properties of sliding objects at the atomic scale and discuss mechanisms of tuning and controlling nanoscale friction. Y. Braiman, F. Family, H. G. E. Hentschel, C. Mak, and J. Krim, Phys. Rev. E 59, R4737 (1999). H. G. E. Hentschel, F. Family, and Y. Braiman, Phys. Rev. Lett. 83, 104 (1999).

  4. 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.

  5. 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

  6. Polarization phase shifting interferometric technique for phase calibration of a reflective phase spatial light modulator

    NASA Astrophysics Data System (ADS)

    Mukhopadhyay, Somparna; Sarkar, Sanjukta; Bhattacharya, Kallol; Hazra, Lakshminarayan

    2013-03-01

    Calibration of phase in spatial light modulators is a prerequisite for applications where a prespecified phase distribution needs to be implemented over the surface of the modulator. The present work proposes a full-field polarization phase shifting interferometric technique, based on the Twyman-Green interferometer, for the purpose.

  7. Geometric phase in Bohmian mechanics

    SciTech Connect

    Chou, Chia-Chun; Wyatt, Robert E.

    2010-10-15

    Using the quantum kinematic approach of Mukunda and Simon, we propose a geometric phase in Bohmian mechanics. A reparametrization and gauge invariant geometric phase is derived along an arbitrary path in configuration space. The single valuedness of the wave function implies that the geometric phase along a path must be equal to an integer multiple of 2{pi}. The nonzero geometric phase indicates that we go through the branch cut of the action function from one Riemann sheet to another when we locally travel along the path. For stationary states, quantum vortices exhibiting the quantized circulation integral can be regarded as a manifestation of the geometric phase. The bound-state Aharonov-Bohm effect demonstrates that the geometric phase along a closed path contains not only the circulation integral term but also an additional term associated with the magnetic flux. In addition, it is shown that the geometric phase proposed previously from the ensemble theory is not gauge invariant.

  8. Joint estimation of phase and phase diffusion for quantum metrology.

    PubMed

    Vidrighin, Mihai D; Donati, Gaia; Genoni, Marco G; Jin, Xian-Min; Kolthammer, W Steven; Kim, M S; Datta, Animesh; Barbieri, Marco; Walmsley, Ian A

    2014-04-14

    Phase estimation, at the heart of many quantum metrology and communication schemes, can be strongly affected by noise, whose amplitude may not be known, or might be subject to drift. Here we investigate the joint estimation of a phase shift and the amplitude of phase diffusion at the quantum limit. For several relevant instances, this multiparameter estimation problem can be effectively reshaped as a two-dimensional Hilbert space model, encompassing the description of an interferometer phase probed with relevant quantum states--split single-photons, coherent states or N00N states. For these cases, we obtain a trade-off bound on the statistical variances for the joint estimation of phase and phase diffusion, as well as optimum measurement schemes. We use this bound to quantify the effectiveness of an actual experimental set-up for joint parameter estimation for polarimetry. We conclude by discussing the form of the trade-off relations for more general states and measurements.

  9. Phase diagrams of polyelectrolyte solutions

    NASA Astrophysics Data System (ADS)

    Mahdi, Khaled A.

    We study the phase diagram of polyelectrolyte solutions in salt and salt-free environments. We examine the phase behavior of polyelectrolyte solutions, in the semidilute regime, using different physical models, namely the Random Phase Approximation (RPA) and the cross-linked model. In the RPA, we calculate the electrostatic free energy by summing all the fluctuations of the chains and all present ionic species. Within this approximation, the phase diagrams of salt-free polyelectrolyte solutions show phase separation even without including short-range attractions or ion condensation. We find that the phase behavior of large chains resembles the phase diagram of polymer network solutions. That is, the equilibrium is established between a network phase and a chain-free phase. Upon the addition of salt, the dissociated ions increase the entropy of the system and overcome the energy from the electrostatic fluctuations. When the short-range attraction between monomers is included in the model, the free energy predicts phase segregation for all salt valences at high salt concentrations (1 mol/l and higher). The phenomenon is called salting-out and occurs simply because the addition of salt reduces the quality of the solvent and induces precipitation. However, phase segregation in the presence of multivalent ions in polyelectrolyte solutions occurs at low salt concentrations (less than 1 mol/l). We propose that this phase separation is due to polyions cross-linked by multivalent ions. We constructed a phenomenological two-state model to examine this phenomenon. The two phases coexisting in the solution are a network-like phase and a polymer-free phase. The polymer-free phase is modeled using Debye-Huckel theory. In the cross-linked phase, each condensed multivalent ion attracts an equal number of monomers creating a neutral cluster. The energy of the cluster is evaluated by a simple Coulombic energy. The bare monomer charges between the linkages are treated as line of

  10. About Phase: Synthetic Aperture Radar and the Phase Retrieval

    DTIC Science & Technology

    2014-03-01

    techniques also enables detection of sudden seismic activity and even volcanic bulging prior to the eruption of volcanoes [2, 48, 71]. Navigation and...in SAR could have a more systematic solution if only additional signal data were available for analysis. The desire for more information motivates...transform. This reduction implies that any method of phase retrieval is also a solution to the phase error problem. We note that phase retrieval is

  11. Ferrite Phase Shifters Using Stress Insensitive Materials. Phase 1

    DTIC Science & Technology

    1992-06-11

    PROGRAM OBJECTIVES 1.3 PROGRAM TECHNICAL TASKS (PHASE I) 2.0 BACKGROUND DISCUSSION 2.1 REMANENT STATE FERRITE PHASERS 2.2 REMANENT MAGNETIZATION 2.3... MAGNETIZATION AND MAGNETOSTRICTION 2.1 REMANENT STATE FERRITE PHASERS Microwave ferrite digital phase shifters utilize ferrite toroidal structures and the...The insertion phase length of the structure is dependent on the remanent magnetization of the ferrite (see the hysteresis loop shown in Figure 2-4

  12. Ion mixing and phase diagrams

    NASA Astrophysics Data System (ADS)

    Lau, S. S.; Liu, B. X.; Nicolet, M.-A.

    1983-05-01

    Interactions induced by ion irradiation are generally considered to be non-equilibrium processes, whereas phase diagrams are determined by phase equilibria. These two entities are seemingly unrelated. However, if one assumes that quasi-equilibrium conditions prevail after the prompt events, subsequent reactions are driven toward equilibrium by thermodynamical forces. Under this assumption, ion-induced reactions are related to equilibrium and therefore to phase diagrams. This relationship can be seen in the similarity that exists in thin films between reactions induced by ion irradiation and reactions induced by thermal annealing. In the latter case, phase diagrams have been used to predict the phase sequence of stable compound formation, notably so in cases of silicide formation. Ion-induced mixing not only can lead to stable compound formation, but also to metastable alloy formation. In some metal-metal systems, terminal solubilities can be greatly extended by ion mixing. In other cases, where the two constituents of the system have different crystal structures, extension of terminal solubility from both sides of the phase diagram eventually becomes structurally incompatible and a glassy (amorphous) mixture can form. The composition range where this bifurcation is likely to occur is in the two-phase regions of the phase diagram. These concepts are potentially useful guides in selecting metal pairs that from metallic glasses by ion mixing. In this report, phenomenological correlation between stable (and metastable) phase formation and phase diagram is discussed in terms of recent experimental data.

  13. Experimental and calculated 1H, 13C, 15N NMR spectra of famotidine

    NASA Astrophysics Data System (ADS)

    Barańska, M.; Czarniecki, K.; Proniewicz, L. M.

    2001-05-01

    Famotidine, 3-[[[2-[(aminoiminomethyl)amino]-4-thiazolyl]methyl]thio]- N-(aminosulfonyl), is a histamine H 2-receptor blocker that has been used mainly for the treatment of peptic ulcers and the Zollinger-Ellison syndrome. Its NMR spectra in different solvents were reported earlier; however, detailed interpretation has not been done thus far. In this work, experimental 1H, 13C and 15N NMR spectra of famotidine dissolved in DMSO-d 6 are shown. The assignment of observed chemical shifts is based on quantum chemical calculation at the Hartree-Fock/6-31G ∗ level. The geometry optimization of the famotidine molecule with two internal hydrogen bonds, i.e. [N(3)-H(23)⋯N(9) and N(3)⋯H(34)-N(20)], is done by using the B3LYP method with the 6-31G ∗ basis set.

  14. 26 CFR 1.381(c)(15)-1 - Indebtedness of certain personal holding companies.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ..., in a transaction otherwise described in this section, an acquiring corporation acquires real estate... the satisfaction of the Commissioner that under all the facts and circumstances it bears the burden...

  15. 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.

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

    SciTech Connect

    Kristin Persson

    2016-03-28

    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

  17. 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

  18. 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.

  19. 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

  20. 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.

  1. 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.

    2009-03-01

    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.

  2. Liquid Phase Sintering

    NASA Technical Reports Server (NTRS)

    2004-01-01

    Industry spends billions of dollars each year on machine tools to manufacture products out of metal. This includes tools for cutting every kind of metal part from engine blocks to Shuttle main engine components. Cutting tool tips often break because of weak spots or defects in their composition. Based on a new concept called defect trapping, space offers a novel environment to study defect formation in molten metal materials as they solidify. After the return of these materials from space, researchers can evaluate the source of the defect and seek ways to eliminate them in products prepared on Earth. A widely used process for cutting tip manufacturing is liquid phase sintering. Compared to Earth-sintered samples which slump due to buoyancy induced by gravity, space samples are uniformly shaped and defects remain where they are formed. By studying metals sintered in space the US tool industry can potentially enhance its worldwide competitiveness. The Consortium for Materials Development in Space along with Wyle Labs, Teledyne Advanced Materials, and McDornell Douglas have conducted experiments in space.

  3. 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.

  4. 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.

  5. 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

  6. 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.

  7. 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.

  8. Digitally controlled distributed phase shifter

    DOEpatents

    Hietala, Vincent M.; Kravitz, Stanley H.; Vawter, Gregory A.

    1993-01-01

    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 or two discrete bias voltages. The application of the discrete bias voltages changes 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.

  9. Digitally controlled distributed phase shifter

    DOEpatents

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

    1993-08-17

    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 or two discrete bias voltages. The application of the discrete bias voltages changes 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.

  10. Oscillatory phase shapes syllable perception

    PubMed Central

    ten Oever, Sanne; Sack, Alexander T.

    2015-01-01

    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

  11. Phase-shift coherence holography.

    PubMed

    Naik, Dinesh N; Ezawa, Takahiro; Miyamoto, Yoko; Takeda, Mitsuo

    2010-05-15

    We propose and experimentally demonstrate a new reconstruction scheme for coherence holography using computer-generated phase-shift coherence holograms. A 3D object encoded into the spatial coherence function is reconstructed directly from a set of incoherently illuminated computer-generated holograms with numerically introduced phase shifts. Although a rotating ground glass is used to introduce spatially incoherent illumination, the phase-shifting portion of the system is simple and free from mechanically moving components.

  12. Compact optical microfiber phase modulator.

    PubMed

    Zhang, Xueliang; Belal, M; Chen, G Y; Song, Zhangqi; Brambilla, G; Newson, T P

    2012-02-01

    A compact optical microfiber phase modulator with MHz bandwidth is presented. A micrometer-diameter microfiber is wound on a millimeter-diameter piezoelectric ceramic rod with two electrodes. When a voltage is applied to the piezoelectric ceramic, the rod is strained, leading to a phase change along the microfiber; because of the small size, the optical microfiber phase modulator can have as high as a few MHz bandwidth response.

  13. Lunar and menstrual phase locking.

    PubMed

    Cutler, W B

    1980-08-01

    In a selected population of 312 women, prospective menses records were maintained during the autumn of 1977. Women whose menstrual cycle duration approaches the cycle duration of the earth's moon (29.5 days) tend to ovulate in the dark phase of the lunar period. The dark phase encompasses the half-cycle of the month from last quarter, through new moon, to first quarter. Women showing irregular menses also tended to ovulate during the dark phase of the lunar period.

  14. Phased Array Theory and Technology

    DTIC Science & Technology

    1981-07-01

    drive the ferrite magnetization to saturation as in a latching phase shifter, or to various points on the magnetization curve with flux drive...can vary from 1 kW to as much as 150 kW peak and average power levels to 400 W. Latching phase shifters have switching times un the order of one...Circuits , and Toroid Ferrite Phase Shifted SO. ode \\rrav Network 26. Dual Slat . 27. PA\\ E PAWS Array (Courtesy of Raytheon Company) 28. Patriot

  15. 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.

  16. 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.

  17. 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.

  18. MANUFACTURING METHODS FOR PHASE SHIFTERS.

    DTIC Science & Technology

    MANUFACTURING), (*PHASE SHIFT CIRCUITS, FERRITES , GARNET, DIGITAL SYSTEMS, X BAND, C BAND, S BAND, RADAR EQUIPMENT, MAGNETIC MATERIALS, YTTRIUM COMPOUNDS, GADOLINIUM COMPOUNDS, ALUMINUM COMPOUNDS, IRON COMPOUNDS, OXIDES.

  19. 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.

  20. Dual-Phase Nozzle Flow.

    DTIC Science & Technology

    1982-10-01

    Two-phase 20. A T RACT (0.31lmm 401 teV9 i 01 000* u...in #CMIdR@0fr &V WNHI& WARNeJ A revieW or the dual-phase -ower system was made. This study ...pr-et5 ._ lnering Dean of Science and Engineering J* ABSTRACT A review of the dual-phase power system was made. This study focused on the multi...be studied in detail, but first a review of the dual-phase cycle will be carried out from information obtained from References 1 and 2. Reference 1

  1. Topological phases of eternal inflation

    NASA Astrophysics Data System (ADS)

    Sekino, Yasuhiro; Shenker, Stephen; Susskind, Leonard

    2010-06-01

    “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.

  2. 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.

  3. Phase estimation for a phased array therapeutic interstitial ultrasound probe.

    PubMed

    Yang, Zhenya; Dillenseger, Jean-Louis

    2012-01-01

    This paper deals about high intensity ultrasound interstitial therapy simulation. The simulated phased array ultrasound probe allows a dynamic electronic focusing of the therapeutic beam. In order to maximize the power deposit at the focal point we propose a method which allows to optimally defining the phase shift of the electrical control signal for each individual element.

  4. Behavior and Sensitivity of Phase Arrival Times (PHASE)

    DTIC Science & Technology

    2014-09-30

    travel -time perturbations, and, further, to study the behavior of phase arrival times and its predictability, depending on propagation and signal...Using this definition, expressions for the corresponding travel -time perturbations are derived and the sensitivity behavior of phase arrival times...corresponding travel -time sensitivity kernels for peak arrivals. DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited

  5. 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

  6. Phase-locked loop with controlled phase slippage

    DOEpatents

    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.

  7. 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.

  8. 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.

  9. 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.

  10. Resolution Of Phase Ambiguities In QPSK

    NASA Technical Reports Server (NTRS)

    Nguyen, Tien M.

    1992-01-01

    Report discusses several techniques for resolution of phase ambiguities in detection and decoding of radio signals modulated by coherent quadrature phase-shift keying (QPSK) and offset QPSK (OQPSK). Eight ambiguities: four associated with phase of carrier signal in absence of ambiguity in direction of rotation of carrier phase, and another four associated with carrier phase in presence of phase-rotation ambiguity.

  11. Oscillator With Low Phase Noise

    NASA Technical Reports Server (NTRS)

    Kleinberg, Leonard L.

    1987-01-01

    Phase errors cancelled for high frequency stability. Radio-frequency oscillator achieves high stability of frequency through parallel, two-amplifier configuration in which effects cause phase noise tend to cancel each other. Circuit includes two amplifiers with resonating elements, each constitutes part of feedback loop of other. Generate same frequency because each circuit provides other with conditions necessary for oscillation.

  12. 78 FR 33911 - Phased Retirement

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-05

    ... Management (OPM) is proposing to implement phased retirement, a new human resources tool that allows full...-21,'' Public Law 112-141. Background Phased retirement is a new human resources management tool made... Benefits (FEHB) and Federal Employees' Group Life Insurance (FEGLI) enrollment will stay with the...

  13. 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

  14. 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

  15. Blue phases of cholesteryl nonanoate

    NASA Astrophysics Data System (ADS)

    Meiboom, S.; Sammon, M.

    1981-07-01

    The transformation on heating of an ordinary (helical) cholesteric liquid crystal (CHOL) into the isotropic phase (ISO) often occurs via a number of intermediate "blue" phases. We find the following scheme of phase transitions in cholesteryl nonanoate: CHOL-->91.35BPI-->91.76BPII-->91.84BPIII-->91.95ISO. Here BPI, BPII, and BPIII indicate three distinct, thermodynamically stable phases; transition temperatures are in °C. From observations of supercooling and coexistence, we conclude that all these transformations are first order, except possibly the BPIII-->ISO, the character of which remains in doubt. A similar behavior is found in cholesteryl myristate and in a mixture of cholesteryl nonanoate and cholesteryl chloride. A few observations having a bearing on the structure of the blue phases are reported.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  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. 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.

  6. 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.

  7. 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

  8. Phase Noise in Photonic Phased-Array Antenna Systems

    NASA Technical Reports Server (NTRS)

    Logan, Ronald T., Jr.; Maleki, Lute

    1998-01-01

    The total noise of a phased-array antenna system employing a photonic feed network is analyzed using a model for the individual component noise including both additive and multiplicative equivalent noise generators.

  9. 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.

  10. 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.

  11. Phase in Optical Image Processing

    NASA Astrophysics Data System (ADS)

    Naughton, Thomas J.

    2010-04-01

    The use of phase has a long standing history in optical image processing, with early milestones being in the field of pattern recognition, such as VanderLugt's practical construction technique for matched filters, and (implicitly) Goodman's joint Fourier transform correlator. In recent years, the flexibility afforded by phase-only spatial light modulators and digital holography, for example, has enabled many processing techniques based on the explicit encoding and decoding of phase. One application area concerns efficient numerical computations. Pushing phase measurement to its physical limits, designs employing the physical properties of phase have ranged from the sensible to the wonderful, in some cases making computationally easy problems easier to solve and in other cases addressing mathematics' most challenging computationally hard problems. Another application area is optical image encryption, in which, typically, a phase mask modulates the fractional Fourier transformed coefficients of a perturbed input image, and the phase of the inverse transform is then sensed as the encrypted image. The inherent linearity that makes the system so elegant mitigates against its use as an effective encryption technique, but we show how a combination of optical and digital techniques can restore confidence in that security. We conclude with the concept of digital hologram image processing, and applications of same that are uniquely suited to optical implementation, where the processing, recognition, or encryption step operates on full field information, such as that emanating from a coherently illuminated real-world three-dimensional object.

  12. ALMA long baseline phase calibration using phase referencing

    NASA Astrophysics Data System (ADS)

    Asaki, Yoshiharu; Matsushita, Satoki; Fomalont, Edward B.; Corder, Stuartt A.; Nyman, Lars-Åke; Dent, William R. F.; Philips, Neil M.; Hirota, Akihiko; Takahashi, Satoko; Vila-Vilaro, Baltasar; Nikolic, Bojan; Hunter, Todd R.; Remijan, Anthony; Vlahakis, Catherine

    2016-08-01

    The Atacama Large Millimeter/submillimeter Array (ALMA) is the world's largest millimeter/submillimeter telescope and provides unprecedented sensitivities and spatial resolutions. To achieve the highest imaging capabilities, interferometric phase calibration for the long baselines is one of the most important subjects: The longer the baselines, the worse the phase stability becomes because of turbulent motions of the Earth's atmosphere, especially, the water vapor in the troposphere. To overcome this subject, ALMA adopts a phase correction scheme using a Water Vapor Radiometer (WVR) to estimate the amount of water vapor content along the antenna line of sight. An additional technique is phase referencing, in which a science target and a nearby calibrator are observed by turn by quickly changing the antenna pointing. We conducted feasibility studies of the hybrid technique with the WVR phase correction and the antenna Fast Switching (FS) phase referencing (WVR+FS phase correction) for the ALMA 16 km longest baselines in cases that (1) the same observing frequency both for a target and calibrator is used, and (2) higher and lower frequencies for a target and calibrator, respectively, with a typical switching cycle time of 20 s. It was found that the phase correction performance of the hybrid technique is promising where a nearby calibrator is located within roughly 3◦ from a science target, and that the phase correction with 20 s switching cycle time significantly improves the performance with the above separation angle criterion comparing to the 120 s switching cycle time. The currently trial phase calibration method shows the same performance independent of the observing frequencies. This result is especially important for the higher frequency observations because it becomes difficult to find a bright calibrator close to an arbitrary sky position. In the series of our experiments, it is also found that phase errors affecting the image quality come from not only

  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. 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.

  18. Phase Instability in Semiconductor Lasers

    NASA Astrophysics Data System (ADS)

    Gil, L.; Lippi, G. L.

    2014-11-01

    For many years, the apparent absence of a phase instability has characterized lasers as peculiar nonlinear oscillators. We show that this unusual feature is solely due to the approximations used in writing the standard models. A new, careful derivation of the fundamental equations, based on codimension 2 bifurcation theory, shows the possible existence of dynamical regimes displaying either a pure phase instability, or mixed phase-amplitude turbulence. A comparison to existing experimental results convincingly shows that the Benjamin-Feir instability, common to all nonlinear wave problems, is a fundamental, satisfactory interpretation for their deterministic multimode dynamics.

  19. Progress Report NORSAR Phase 3

    DTIC Science & Technology

    1974-10-11

    PHASE 3 1 July - 30 September 1974 1 AUTHOR’«; Prepared by K.A. Berteussen 9 PERFORMING ORGANIZATION NAME AND ADDRESS NTNF...30 June 1975 F08606-74-C-0049 Norwegian Seismic Array (NORSAR) Phase 3 $900 000.— II October 1974 1 July - 30 September 197 4 Nils Maräs, (02)71...Hi.»,«—, Hl .1 ii.li in im. UM;!..». .1.1 „IM I,„LWII ■Mtffll^ A D/A-00 2 25 2 PROGRESS REPORT NORSAR PHASE

  20. Progress Report NORSAR Phase 3

    DTIC Science & Technology

    1975-04-11

    1 A I)-A 010 5 86 PROGRriSS REPORT NORSAR PHASE 3 K . /\\ . B c r t c u s s e n Royal Norwegian Council for Scientific and...NORSAR ROYAl NORWEGIAN COUNCIL FOR SCIENTIFIC AND INDUSTRIAL RESEARCH <o<: 00 10’ o H O < F 8606-74-C-0049 PROGRESS REPORT - NORSAR PHASE 3 1...Report NORSAR Phase 3 1st Quarter 1975 5 TYPE OE REPORT « PERIOD COVERED Progress Report 1st Quarter 1975 6 PERFORMING ORG

  1. 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

  2. Chromatography with two mobile phases.

    PubMed

    Wang, M; Hou, S; Parcher, J F

    2006-02-15

    Experimental results for the investigation of chromatographic columns containing two mobile phases are presented. The eluent was composed of mixtures of methanol and carbon dioxide. The column was an uncoated fused-silica-lined stainless steel capillary column. At certain experimental conditions, the eluent divided into two phases, both of which moved through the column. The predominant component of the liquid phase was methanol whereas the gas phase was composed of at least 93 mol % CO2. The columns were studied over a range of feed compositions (45-95 mol % CO2), pressures (61-101 bar), and temperatures (30-100 degrees C). The compositions and densities of each phase were calculated from the Peng-Robinson equation of state. The residence times of the two mobile phases were determined by tracer pulse chromatography. The partition coefficients of a probe solute, benzene, were measured along with the retention times of neon and the total volume of the chromatographic column as a function of temperature, pressure, and stoichiometric feed composition. The calculated column volumes, that is the volume of the liquid and gas, were constant over the full range of feed composition. The partition coefficient of benzene was constant at fixed pressure and temperature, varied logarithmically with density at fixed temperature and feed composition, and displayed a maximum at intermediate temperatures at fixed pressure and feed composition. The measured retention times of neon were consistently equivalent to the calculated residence times of the gas phase, indicating that neon did not dissolve in the liquid phase and could thus serve as an accurate dead time marker. The implementation of chromatography with two mobile phases produces a chromatographic "window". There is a lower limit for the retention volume of all solutes, viz., the residence time of the gas phase, exactly the same as normal chromatography. However, elimination of the stationary phase produces an upper limit to

  3. 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.

  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. Wavelet phase synchronization and chaoticity.

    PubMed

    Postnikov, E B

    2009-11-01

    It has been shown that the so-called "wavelet phase" (or "time-scale") synchronization of chaotic signals is actually synchronization of smoothed functions with reduced chaotic fluctuations. This fact is based on the representation of the wavelet transform with the Morlet wavelet as a solution of the Cauchy problem for a simple diffusion equation with initial condition in a form of harmonic function modulated by a given signal. The topological background of the resulting effect is discussed. It is argued that the wavelet phase synchronization provides information about the synchronization of an averaged motion described by bounding tori instead of the fine-level classical chaotic phase synchronization.

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

    DOE PAGES

    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.

  8. 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 ...

  9. Phase retrieval in protein crystallography.

    PubMed

    Liu, Zhong Chuan; Xu, Rui; Dong, Yu Hui

    2012-03-01

    Solution of the phase problem is central to crystallographic structure determination. An oversampling method is proposed, based on the hybrid input-output algorithm (HIO) [Fienup (1982). Appl. Opt. 21, 2758-2769], to retrieve the phases of reflections in crystallography. This method can extend low-resolution structures to higher resolution for structure determination of proteins without additional sample preparation. The method requires an envelope of the protein which divides a unit cell into the density region where the proteins are located and the non-density region occupied by solvents. After a few hundred to a few thousand iterations, the correct phases and density maps are recovered. The method has been used successfully in several cases to retrieve the phases from the experimental X-ray diffraction data and the envelopes of proteins constructed from structure files downloaded from the Protein Data Bank. It is hoped that this method will greatly facilitate the ab initio structure determination of proteins.

  10. Integrated optical phase locked loop.

    SciTech Connect

    Lentine, Anthony L.; Kim, Jungwon; Trotter, Douglas Chandler; DeRose, Christopher T.; Kartner, Franz X.; Byun, Hyunil; Nejadmalayeri, Amir H.; Watts, Michael R.; Zortman, William A.

    2010-12-01

    A silicon photonics based integrated optical phase locked loop is utilized to synchronize a 10.2 GHz voltage controlled oscillator with a 509 MHz mode locked laser, achieving 32 fs integrated jitter over 300 kHz bandwidth.

  11. APPARATUS FOR LIQUID PHASE EXTRACTION

    DOEpatents

    Hicks, T.R.; Lehman, H.R.; Rubin, B.

    1958-09-16

    operation is described. It comprises a tubular colunm having upper and lower enlarged terminal portions, and a constricted central section containing fluid dispersal packing. Pulsing means are coupled to the upper portion of the column. The inlet for the less dense phase is located above the inlet for the denser phase and both are positioned so that liquids enter the constricted packingfilled central section. The apparatos also includes an interfacing level control, and means fer sensing the level of the interface actuate apparatus for controlling the rate of flow of input or discharge. The outlet for the less dense phase is located in the upper packing free portion of the colunm and that of the denser phase in the lower portion.

  12. 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.

  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. 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

  15. Guiding light via geometric phases

    NASA Astrophysics Data System (ADS)

    Slussarenko, Sergei; Alberucci, Alessandro; Jisha, Chandroth P.; Piccirillo, Bruno; Santamato, Enrico; Assanto, Gaetano; Marrucci, Lorenzo

    2016-09-01

    All known methods for transverse confinement and guidance of light rely on modification of the refractive index, that is, on the scalar properties of electromagnetic radiation. Here, we disclose the concept of a dielectric waveguide that exploits vectorial spin-orbit interactions of light and the resulting geometric phases. The approach relies on the use of anisotropic media with an optic axis that lies orthogonal to the propagation direction but is spatially modulated, so that the refractive index remains constant everywhere. A spin-controlled cumulative phase distortion is imposed on the beam, balancing diffraction for a specific polarization. As well as theoretical analysis, we present an experimental demonstration of the guidance using a series of discrete geometric-phase lenses made from liquid crystal. Our findings show that geometric phases may determine the optical guiding behaviour well beyond a Rayleigh length, paving the way to a new class of photonic devices. The concept is applicable to the whole electromagnetic spectrum.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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).).

  1. 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.

  2. 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.

  3. AXKT Phase 3 Final Report

    DTIC Science & Technology

    1993-07-06

    AD-A275 236 - July 6 1993 AXKT PHASE 3 FINAL REPORT CONTRACT N00014-88-C-6027 CDRL A013 I NE * ,~ 9M SUBMITSED BY W80co 02 SIPPICAN, INC.I...Funding Numbers. AXKT Phase 3 Final Report Contract NOOQI 4-88-C-6027 PrOgram Elemeni No. 0603704N 6. Auw~) Project No. R01i180 Task fo. 300 Accession No

  4. 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.

  5. Interfacial phase-change memory.

    PubMed

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

    2011-07-03

    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.

  6. Resolving Phase Ambiguities In OQPSK

    NASA Technical Reports Server (NTRS)

    Nguyen, Tien M.

    1991-01-01

    Improved design for modulator and demodulator in offset-quaternary-phase-key-shifting (OQPSK) communication system enables receiver to resolve ambiguity in estimated phase of received signal. Features include unique-code-word modulation and detection and digital implementation of Costas loop in carrier-recovery subsystem. Enchances performance of carrier-recovery subsystem, reduces complexity of receiver by removing redundant circuits from previous design, and eliminates dependence of timing in receiver upon parallel-to-serial-conversion clock.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. Fiber optic phase stepping system for interferometry

    NASA Technical Reports Server (NTRS)

    Mercer, Carolyn R.; Beheim, Glenn

    1991-01-01

    A closed loop phase control system using an all-fiber optical configuration has been developed for use in phase-stepping interferometry. This system drives the relative phase of two interfering beams through a sequence of pi/2 rad increments so that the initial relative phase of these beams can be determined. This phase-stepping system uses optical fibers to provide spatially uniform phase steps from a flexible, easily aligned optical configuration. In addition, this system uses phase feedback to eliminate phase modulator errors and to compensate for phase drifts caused by environmental disturbances.

  17. Monodomain Blue Phase Liquid Crystal Layers for Phase Modulation

    PubMed Central

    Oton, E.; Netter, E.; Nakano, T.; D.-Katayama, Y.; Inoue, F.

    2017-01-01

    Liquid crystal “Blue Phases” (BP) have evolved, in the last years, from a scientific curiosity to emerging materials for new photonic and display applications. They possess attractive features over standard nematic liquid crystals, like submillisecond switching times and polarization- independent optical response. However, BPs still present a number of technical issues that prevent their use in practical applications: their phases are only found in limited temperature ranges, thus requiring stabilization of the layers; stabilized BP layers are inhomogeneous and not uniformly oriented, which worsen the optical performance of the devices. It would be essential for practical uses to obtain perfectly aligned and oriented monodomain BP layers, where the alignment and orientation of the cubic lattice are organized in a single 3D structure. In this work we have obtained virtually perfect monodomain BP layers and used them in devices for polarization independent phase modulation. We demonstrate that, under applied voltage, well aligned and oriented layers generate smoother and higher values of the phase shift than inhomogeneous layers, while preserving polarization independency. All BP devices were successfully stabilized in BPI phase, maintaining the layer monodomain homogeneity at room temperature, covering the entire area of the devices with a unique BP phase. PMID:28281691

  18. Monodomain Blue Phase Liquid Crystal Layers for Phase Modulation

    NASA Astrophysics Data System (ADS)

    Oton, E.; Netter, E.; Nakano, T.; D.-Katayama, Y.; Inoue, F.

    2017-03-01

    Liquid crystal “Blue Phases” (BP) have evolved, in the last years, from a scientific curiosity to emerging materials for new photonic and display applications. They possess attractive features over standard nematic liquid crystals, like submillisecond switching times and polarization- independent optical response. However, BPs still present a number of technical issues that prevent their use in practical applications: their phases are only found in limited temperature ranges, thus requiring stabilization of the layers; stabilized BP layers are inhomogeneous and not uniformly oriented, which worsen the optical performance of the devices. It would be essential for practical uses to obtain perfectly aligned and oriented monodomain BP layers, where the alignment and orientation of the cubic lattice are organized in a single 3D structure. In this work we have obtained virtually perfect monodomain BP layers and used them in devices for polarization independent phase modulation. We demonstrate that, under applied voltage, well aligned and oriented layers generate smoother and higher values of the phase shift than inhomogeneous layers, while preserving polarization independency. All BP devices were successfully stabilized in BPI phase, maintaining the layer monodomain homogeneity at room temperature, covering the entire area of the devices with a unique BP phase.

  19. Combinatorial entropy and phase diagram of partially ordered ice phases.

    PubMed

    Macdowell, Luis G; Sanz, Eduardo; Vega, Carlos; Abascal, José Luis F

    2004-11-22

    A close analytical estimate for the combinatorial entropy of partially ordered ice phases is presented. The expression obtained is very general, as it can be used for any ice phase obeying the Bernal-Fowler rules. The only input required is a number of crystallographic parameters, and the experimentally observed proton site occupancies. For fully disordered phases such as hexagonal ice, it recovers the result deduced by Pauling, while for fully ordered ice it is found to vanish. Although the space groups determined for ice I, VI, and VII require random proton site occupancies, it is found that such random allocation of protons does not necessarily imply random orientational disorder. The theoretical estimate for the combinatorial entropy is employed together with free energy calculations in order to obtain the phase diagram of ice from 0 to 10 GPa. Overall qualitative agreement with experiment is found for the TIP4P model of water. An accurate estimate of the combinatorial entropy is found to play an important role in determining the stability of partially ordered ice phases, such as ice III and ice V.

  20. Phase-field crystal model with a vapor phase

    NASA Astrophysics Data System (ADS)

    Schwalbach, Edwin J.; Warren, James A.; Wu, Kuo-An; Voorhees, Peter W.

    2013-08-01

    Phase-field crystal (PFC) models are able to resolve atomic length scale features of materials during temporal evolution over diffusive time scales. Traditional PFC models contain solid and liquid phases, however many important materials processing phenomena involve a vapor phase as well. In this work, we add a vapor phase to an existing PFC model and show realistic interfacial phenomena near the triple point temperature. For example, the PFC model exhibits density oscillations at liquid-vapor interfaces that compare favorably to data available for interfaces in metallic systems from both experiment and molecular-dynamics simulations. We also quantify the anisotropic solid-vapor surface energy for a two-dimensional PFC hexagonal crystal and find well-defined step energies from measurements on the faceted interfaces. Additionally, the strain field beneath a stepped interface is characterized and shown to qualitatively reproduce predictions from continuum models, simulations, and experimental data. Finally, we examine the dynamic case of step-flow growth of a crystal into a supersaturated vapor phase. The ability to model such a wide range of surface and bulk defects makes this PFC model a useful tool to study processing techniques such as chemical vapor deposition or vapor-liquid-solid growth of nanowires.

  1. Phase-field crystal model with a vapor phase.

    PubMed

    Schwalbach, Edwin J; Warren, James A; Wu, Kuo-An; Voorhees, Peter W

    2013-08-01

    Phase-field crystal (PFC) models are able to resolve atomic length scale features of materials during temporal evolution over diffusive time scales. Traditional PFC models contain solid and liquid phases, however many important materials processing phenomena involve a vapor phase as well. In this work, we add a vapor phase to an existing PFC model and show realistic interfacial phenomena near the triple point temperature. For example, the PFC model exhibits density oscillations at liquid-vapor interfaces that compare favorably to data available for interfaces in metallic systems from both experiment and molecular-dynamics simulations. We also quantify the anisotropic solid-vapor surface energy for a two-dimensional PFC hexagonal crystal and find well-defined step energies from measurements on the faceted interfaces. Additionally, the strain field beneath a stepped interface is characterized and shown to qualitatively reproduce predictions from continuum models, simulations, and experimental data. Finally, we examine the dynamic case of step-flow growth of a crystal into a supersaturated vapor phase. The ability to model such a wide range of surface and bulk defects makes this PFC model a useful tool to study processing techniques such as chemical vapor deposition or vapor-liquid-solid growth of nanowires.

  2. The gas-phase ozonolysis of α-humulene.

    PubMed

    Beck, M; Winterhalter, R; Herrmann, F; Moortgat, G K

    2011-06-21

    α-Humulene contains three double bonds (DB), and after ozonolysis of the first DB the first-generation products are still reactive towards O(3) and produce second- and third-generation products. The primary aim of this study consisted of identifying the products of the three generations, focusing on the carboxylic acids, which are known to have a high aerosol formation potential. The experiments were performed in a 570 litre spherical glass reactor at 295 K and 730 Torr. Initial mixing ratios were 260-2090 ppb for O(3) and 250-600 ppb for α-humulene in synthetic air. Reactants and gas-phase products were measured by in situ FTIR spectroscopy. Particulate products were sampled on Teflon filters, extracted with methanol and analyzed by LC-MS/MS-TOF. Using cyclohexane (10-100 ppm) as an OH-radical scavenger and by monitoring the yield of cyclohexanone by PTR-MS, an OH-yield of (10.5 ± 0.7)% was determined for the ozonolysis of the first DB, and (12.9 ± 0.7)% of the first-generation products. The rate constant of the reaction of O(3) with α-humulene is known as k(0) = 1.17 × 10(-14) cm(3) molecule(-1) s(-1) [Y. Shu and R. Atkinson, Int. J. Chem. Kinet., 1994, 26, 1193-1205]. The reaction rate constants of O(3) with the first-generation products and the second-generation products were, respectively, determined as k(1) = (3.6 ± 0.9) × 10(-16) and k(2) = (3.0 ± 0.7) × 10(-17) cm(3) molecule(-1) s(-1) by Facsimile-simulation of the observed ozone decay by FTIR. A total of 37 compounds in the aerosol phase and 5 products in the gas phase were tentatively identified: 25 compounds of the first-generation products contained C13-C15 species, 9 compounds of the second-generation products contained C8-C11 species, whereas 8 compounds of the third-generation products contained C4-C6 species. The products of all three generations consisted of a variety of dicarboxylic-, hydroxy-oxocarboxylic- and oxo-carboxylic acids. The formation mechanisms of some of the products are

  3. EUVL alternating phase shift mask

    NASA Astrophysics Data System (ADS)

    Yan, Pei-Yang; Myers, Alan; Shroff, Yashesh; Chandhok, Manish; Zhang, Guojing; Gullikson, Eric; Salmassi, Farhad

    2011-04-01

    Extreme ultra-violet Lithography (EUVL) alternating phase shift mask (APSM) or other optical enhancement techniques are likely needed for 16nm (half pitch) technology generation and beyond. One possible option is the combination of EUVL and APSM. The fabrication of EUVL APSM is more difficult than either the fabrication of an EUVL binary mask or a conventional optical APSM mask. In the case of EUVL APSM, the phase difference in the two regions (0 and 180-degree phase regions) is created by a phase step in the substrate prior to the multilayer (ML) coating. The step height that induces 180-degree phase mismatch in the ML is determined by [λ/(4cosθ)](2m+1), where m are integers (0, 1, 2,...). In this experiment, we targeted for a step height with m=1. The same mask design also contains the standard binary structures so that the comparison between the EUVL APSM and the EUVL binary mask can be performed under the same illumination and wafer process conditions. The EUVL APSM mask was exposed using Nikon's EUV1 scanner in Kumagaya Japan. The wafer level results showed higher dense line resolution for EUVL APSM as compared to that of EUVL binary mask. APSM also showed improved line width roughness (LWR) and depth of focus (DoF) as compared to the best EUVL binary results obtained with C-dipole off-axis illumination (OAI). The wafer CD resolution improvement obtained by APSM in this experiment is partially limited by the resist resolution and the mask phase edge spread during ML deposition. We believe that wafer CD resolution and can further be improved with imaging imbalance compensation mask design and improvements in resist resolution and the phase generation portion of the mask fabrication process. In this paper, we will discuss in detail the mask fabrication process, wafer level data analysis, and our understanding of EUVL APSM related issues.

  4. 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.

  5. An advanced phase retrieval algorithm in N-step phase-shifting interferometry with unknown phase shifts

    PubMed Central

    Li, Jiaosheng; Zhong, Liyun; Liu, Shengde; Zhou, Yunfei; Xu, Jie; Tian, Jindong; Lu, Xiaoxu

    2017-01-01

    In phase-shifting interferometry with unknown phase shifts, a normalization and orthogonalization phase-shifting algorithm (NOPSA) is proposed to achieve phase retrieval. The background of interferogram is eliminated through using the orthogonality of complex sinusoidal function; and the influence of phase shifts deviation on accuracy of phase retrieval is avoided through both normalization and orthogonalization processing. Compared with the current algorithms with unknown phase shifts, the proposed algorithm reveals significantly faster computation speed, higher accuracy, better stability and non-sensitivity of phase shifts deviation. PMID:28290494

  6. An advanced phase retrieval algorithm in N-step phase-shifting interferometry with unknown phase shifts

    NASA Astrophysics Data System (ADS)

    Li, Jiaosheng; Zhong, Liyun; Liu, Shengde; Zhou, Yunfei; Xu, Jie; Tian, Jindong; Lu, Xiaoxu

    2017-03-01

    In phase-shifting interferometry with unknown phase shifts, a normalization and orthogonalization phase-shifting algorithm (NOPSA) is proposed to achieve phase retrieval. The background of interferogram is eliminated through using the orthogonality of complex sinusoidal function; and the influence of phase shifts deviation on accuracy of phase retrieval is avoided through both normalization and orthogonalization processing. Compared with the current algorithms with unknown phase shifts, the proposed algorithm reveals significantly faster computation speed, higher accuracy, better stability and non-sensitivity of phase shifts deviation.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. What Phase Matters for Diffraction?

    NASA Astrophysics Data System (ADS)

    Jones, Eric; Bach, Roger; Batelaan, Herman

    2014-05-01

    Young's double-slit experiment for matter is often compared to that of optics. In rudimentary explanations of the locations of the diffraction maxima and minima far from the slits, paths are sometimes superimposed over waves drawn from the two slits to the detection screen, leading to a phase difference of Δϕ = 2 πΔL /λdB between paths. Despite the intuitive connection of the two kinds of wave phenomena, this approach can lead to a misunderstanding of the theory for matter waves. The Feynman path-integral formalism justifies the use of paths to determine the phase difference; however, the phase accumulated along single free-particle paths according to the formalism is not ϕ = 2 πL /λdB , even though the expression for the phase difference is correct. The resulting factor of 2 difference in the single path phase from the intuitive value arises from the particular treatment of time-dependence in interpreting the problem. The nature of this misunderstanding will be discussed, and a possible resolution proposed based on the quantum mechanical principle of indistinguishability: the time duration of all interfering paths must be equal. We gratefully acknowledge support from the NSF.

  12. Modeling of phased array transducers.

    PubMed

    Ahmad, Rais; Kundu, Tribikram; Placko, Dominique

    2005-04-01

    Phased array transducers are multi-element transducers, where different elements are activated with different time delays. The advantage of these transducers is that no mechanical movement of the transducer is needed to scan an object. Focusing and beam steering is obtained simply by adjusting the time delay. In this paper the DPSM (distributed point source method) is used to model the ultrasonic field generated by a phased array transducer and to study the interaction effect when two phased array transducers are placed in a homogeneous fluid. Earlier investigations modeled the acoustic field for conventional transducers where all transducer points are excited simultaneously. In this research, combining the concepts of delayed firing and the DPSM, the phased array transducers are modeled semi-analytically. In addition to the single transducer modeling the ultrasonic fields from two phased array transducers placed face to face in a fluid medium is also modeled to study the interaction effect. The importance of considering the interaction effect in multiple transducer modeling is discussed, pointing out that neighboring transducers not only act as ultrasonic wave generators but also as scatterers.

  13. 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.

  14. Phases of cannibal dark matter

    NASA Astrophysics Data System (ADS)

    Farina, Marco; Pappadopulo, Duccio; Ruderman, Joshua T.; Trevisan, Gabriele

    2016-12-01

    A hidden sector with a mass gap undergoes an epoch of cannibalism if number changing interactions are active when the temperature drops below the mass of the lightest hidden particle. During cannibalism, the hidden sector temperature decreases only logarithmically with the scale factor. We consider the possibility that dark matter resides in a hidden sector that underwent cannibalism, and has relic density set by the freeze-out of two-to-two annihilations. We identify three novel phases, depending on the behavior of the hidden sector when dark matter freezes out. During the cannibal phase, dark matter annihilations decouple while the hidden sector is cannibalizing. During the chemical phase, only two-to-two interactions are active and the total number of hidden particles is conserved. During the one way phase, the dark matter annihilation products decay out of equilibrium, suppressing the production of dark matter from inverse annihilations. We map out the distinct phenomenology of each phase, which includes a boosted dark matter annihilation rate, new relativistic degrees of freedom, warm dark matter, and observable distortions to the spectrum of the cosmic microwave background.

  15. Closed Orbits in Phase Space

    NASA Astrophysics Data System (ADS)

    Murphy, Andrew; Haestad, Jace; Morgan, Thomas

    2015-09-01

    We report characteristics of closed classical orbits in an electric field in phase space produced in photoabsorption. Rydberg states of atomic and molecular hydrogen and helium are considered. The core potential used for the hydrogen molecule is an effective one electron one center core potential evaluated at the internuclear equilibrium distance. Poincare surfaces of section in phase space are generated by integrating the equations of motion in semiparabolic coordinates u = (r + z) 1 / 2 and v = (r - z) 1 / 2, and plotting the location in phase space (pv versus v) whenever u = 0, with the electric field in the z direction. Combination orbits produced by Rydberg electron core scattering are studied and the evolution in phase space of these combination orbits due to scattering from one closed orbit into another is investigated. Connections are made to measured laser photoabsorption experiments that excite Rydberg states (20 < n < 30) and produce accompanying scaled energy recurrence spectra. The phase space structures responsible for the spectra are identified.

  16. 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.

  17. Origin and use of crystallization phase diagrams

    PubMed Central

    Rupp, Bernhard

    2015-01-01

    Crystallization phase diagrams are frequently used to conceptualize the phase relations and also the processes taking place during the crystallization of macromolecules. While a great deal of freedom is given in crystallization phase diagrams owing to a lack of specific knowledge about the actual phase boundaries and phase equilibria, crucial fundamental features of phase diagrams can be derived from thermodynamic first principles. Consequently, there are limits to what can be reasonably displayed in a phase diagram, and imagination may start to conflict with thermodynamic realities. Here, the commonly used ‘crystallization phase diagrams’ are derived from thermodynamic excess properties and their limitations and appropriate use is discussed. PMID:25760697

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. Phase diagram of ammonium nitrate

    NASA Astrophysics Data System (ADS)

    Dunuwille, Mihindra; Yoo, Choong-Shik

    2013-12-01

    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 N2, N2O, and H2O 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' transition above 17 GPa and provide new constraints for the melting and phase diagram of AN to 40 GPa and 400°C.

  4. Lensless phase microscopy using phase retrieval with multiple illumination wavelengths.

    PubMed

    Bao, Peng; Situ, Guohai; Pedrini, Giancarlo; Osten, Wolfgang

    2012-08-01

    A phase retrieval method for microscopy using multiple illumination wavelengths is proposed. A fast algorithm suitable for calculations with high numerical aperture is used for the iterative retrieval of the object wavefront. The advantages and limitations of the technique are systematically analyzed and demonstrated by both simulation and experimental results.

  5. Scrutinizing the pion condensed phase

    NASA Astrophysics Data System (ADS)

    Carignano, Stefano; Lepori, Luca; Mammarella, Andrea; Mannarelli, Massimo; Pagliaroli, Giulia

    2017-02-01

    When the isospin chemical potential exceeds the pion mass, charged pions condense in the zero-momentum state forming a superfluid. Chiral perturbation theory provides a very powerful tool for studying this phase. However, the formalism that is usually employed in this context does not clarify various aspects of the condensation mechanism and makes the identification of the soft modes problematic. We re-examine the pion condensed phase using different approaches within the chiral perturbation theory framework. As a first step, we perform a low-density expansion of the chiral Lagrangian valid close to the onset of the Bose-Einstein condensation. We obtain an effective theory that can be mapped to a Gross-Pitaevskii Lagrangian in which, remarkably, all the coefficients depend on the isospin chemical potential. The low-density expansion becomes unreliable deep in the pion condensed phase. For this reason, we develop an alternative field expansion deriving a low-energy Lagrangian analog to that of quantum magnets. By integrating out the "radial" fluctuations we obtain a soft Lagrangian in terms of the Nambu-Goldstone bosons arising from the breaking of the pion number symmetry. Finally, we test the robustness of the second-order transition between the normal and the pion condensed phase when next-to-leading-order chiral corrections are included. We determine the range of parameters for turning the second-order phase transition into a first-order one, finding that the currently accepted values of these corrections are unlikely to change the order of the phase transition.

  6. EHF multifunction phased array antenna

    NASA Astrophysics Data System (ADS)

    Solbach, Klaus

    1986-07-01

    The design of a low cost demonstration EHF multifunction-phased array antenna is described. Both, the radiating elements and the phase-shifter circuits are realized on microstrip substrate material in order to allow photolithographic batch fabrication. Self-encapsulated beam-lead PIN-diodes are employed as the electronic switch elements to avoid expensive hermetic encapsulation of the semiconductors or complete circuits. A space-feed using a horn-radiator to illuminate the array from the front-side is found to be the simplest and most inexpensive feed. The phased array antenna thus operates as a reflect-array, the antenna elements employed in a dual role for the collection of energy from the feed-horn and for the re-radiation of the phase-shifted waves (in transmit-mode). The antenna is divided into modules containing the radiator/phase-shifter plate plus drive- and BITE-circuitry at the back. Both drive- and BITE-components use gate-array integrated circuits especially designed for the purpose. Several bus-systems are used to supply bias and logical data flows to the modules. The beam-steering unit utilizes several signal processors and high-speed discrete adder circuits to combine the pointing, frequency and beam-shape information from the radar system computer with the stored phase-shift codes for the array elements. Since space, weight and power consumption are prime considerations only the most advanced technology is used in the design of both the microwave and the digital/drive circuitry.

  7. Isolation of α-linolenic acid biohydrogenation products by combined silver ion solid phase extraction and semi-preparative high performance liquid chromatography.

    PubMed

    Turner, T D; Meadus, W J; Mapiye, C; Vahmani, P; López-Campos, Ó; Duff, P; Rolland, D C; Church, J S; Dugan, M E R

    2015-02-01

    Polyunsaturated fatty acids typically found in cattle feed include linoleic (LA) and α-linolenic acid (ALA). In the rumen, microbes metabolize these resulting in the formation of biohydrogenation products (BHP), which can be incorporated into meat and milk. Bioactivities of LA-BHP, including conjugated linoleic acid (cis (c) 9,trans (t) 11-18:2 and t10,c12-18:2) and trans fatty acid isomers (t9-, t10- and t11-18:1) have been investigated, but effects of several BHP unique to ALA have not been extensively studied, and most ALA-BHP are not commercially available. The objective of the present research was to develop methods to purify and collect ALA-BHP using silver ion (Ag(+)) chromatography in sufficient quantities to allow for convenient bioactivity testing in cell culture. Fatty acid methyl esters (FAME) were prepared from perirenal adipose tissue from a cow enriched with ALA-BHP by feeding flaxseed. These were applied to Ag(+)-solid phase extraction, and eluted with hexane with increasing quantities of acetone (1, 2, 10, 20%) or acetonitrile (2%) to pre-fractionate FAME based on degree of unsaturation and double bond configuration. Fractions were collected, concentrated and applied to semi-preparative Ag(+)-high performance liquid chromatography (HPLC) for the isolation and collection of purified isomers, which was accomplished using isocratic elutions with hexane containing differing amounts of acetonitrile (from 0.015 to 0.075%). Purified trans-18:1 isomers collected ranged in purity from 88 to 99%. Purity of the ALA-BHP dienes collected, including c9,t13-18:2, t11,c15-18:2 and t10,c15-18:2, exceeded 90%, while purification of other dienes may require the use of other complementary procedures (e.g. reverse phase HPLC).

  8. Compressed sensing for phase retrieval.

    PubMed

    Newton, Marcus C

    2012-05-01

    To date there are several iterative techniques that enjoy moderate success when reconstructing phase information, where only intensity measurements are made. There remains, however, a number of cases in which conventional approaches are unsuccessful. In the last decade, the theory of compressed sensing has emerged and provides a route to solving convex optimisation problems exactly via ℓ(1)-norm minimization. Here the application of compressed sensing to phase retrieval in a nonconvex setting is reported. An algorithm is presented that applies reweighted ℓ(1)-norm minimization to yield accurate reconstruction where conventional methods fail.

  9. Phase behavior of methane haze.

    PubMed

    Signorell, R; Jetzki, M

    2007-01-05

    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.

  10. Holographically Encoded Volume Phase Masks

    DTIC Science & Technology

    2015-07-13

    experiments have been performed using an HPM recorded in a 1.97-mm thick photo -thermo-refractive (PTR) glass sample as illustrated in Fig. 1. PTR glass is a...spiral phase plate,” Appl. Opt. 43(12), 2397–2399 (2004). 19. K. Peithmann et al., “Low-spatial-frequency refractive-index changes in iron- doped ...Binary volume phase masks in photo -thermo-refrac- tive glass,” Opt. Lett. 37(7), 1190–1192 (2012). 21. M. Bass, Handbook of Optics, 2nd ed., McGraw-Hill

  11. Closure phase and lucky imaging.

    PubMed

    Rhodes, William T

    2009-01-01

    Since its introduction by Jennison in 1958, the closure-phase method for removing the effects of electrical path-length errors in radio astronomy and of atmospheric turbulence in optical astronomy has been based on the non-redundant-spacing triple interferometer. It is shown that through application of lucky imaging concepts it is possible to relax this condition, making closure-phase methods possible with redundantly spaced interferometer configurations and thereby widening their range of application. In particular, a quadruple-interferometer can, under lucky imaging conditions, be treated as though it were a triple interferometer. The slit-annulus aperture is investigated as a special case.

  12. Phase transition in Liouville theory

    SciTech Connect

    Johnston, D. )

    1989-11-15

    We suggest that the vortices arising in a Kosterlitz-Thouless phase transition in Liouville theory correspond to transitions between different genera, producing the plumber's nightmare'' and other phases that have been predicted in fluid membrane theory from energetic considerations. This transition has previously been invoked by Cates to explain the degeneration of numerical simulations of Gaussian random surfaces into branched polymers. The difficulty in quantizing Liouville theory for {ital d}{gt}1 is conjectured to be due to our insistence on working at a fixed genus.

  13. Phase transition in Liouville theory

    NASA Astrophysics Data System (ADS)

    Johnston, D.

    1989-11-01

    We suggest that the vortices arising in a Kosterlitz-Thouless phase transition in Liouville theory correspond to transitions between different genera, producing the ``plumber's nightmare'' and other phases that have been predicted in fluid membrane theory from energetic considerations. This transition has previously been invoked by Cates to explain the degeneration of numerical simulations of Gaussian random surfaces into branched polymers. The difficulty in quantizing Liouville theory for d>1 is conjectured to be due to our insistence on working at a fixed genus.

  14. Moving walls and geometric phases

    NASA Astrophysics Data System (ADS)

    Facchi, Paolo; Garnero, Giancarlo; Marmo, Giuseppe; Samuel, Joseph

    2016-09-01

    We unveil the existence of a non-trivial Berry phase associated to the dynamics of a quantum particle in a one dimensional box with moving walls. It is shown that a suitable choice of boundary conditions has to be made in order to preserve unitarity. For these boundary conditions we compute explicitly the geometric phase two-form on the parameter space. The unboundedness of the Hamiltonian describing the system leads to a natural prescription of renormalization for divergent contributions arising from the boundary.

  15. 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

  16. Small Business Innovation Research GRC Phase I, Phase II, and Post-Phase II Opportunity Assessment for 2015

    NASA Technical Reports Server (NTRS)

    Nguyen, Hung D.; Steele, Gynelle C.

    2016-01-01

    This report outlines the 2015 Small Business Innovation Research/Small Business Technology Transfer (SBIR/STTR) Phase I, Phase II, and Post-Phase II opportunity contract award results associated with NASA's Aeronautics Research Mission Directorate (ARMD), Human Exploration and Operations Mission Directorate (HEOMD), Science Mission Directorate (SMD), and Space Technology Mission Directorate (STMD) for NASA Glenn Research Center. The report also highlights the number of Phase I, Phase II, and Post-Phase II contracts awarded by mission directorate. The 2015 Phase I contract awards to companies in Ohio and their corresponding technologies are also discussed.

  17. Miniature Color Display Phase 4

    DTIC Science & Technology

    1993-05-01

    is used to generate full color. By spectral tuning of the xenon arc-lamp backlight and the color polarizers, a color gamut comparable to that of a...5 1.2 Phase IV Accom plishments ................................... 5 1.2.1 Subtractive Color Gamut ...Technical Achievem ents .............................................. 8 2.1 Subtractive Color Gamut 2.1.1 Sub Color LC Technology

  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. Phase Detection Using Neural Networks.

    DTIC Science & Technology

    1997-03-10

    A likelihood of detecting a reflected signal characterized by phase discontinuities and background noise is enhanced by utilizing neural networks to...identify coherency intervals. The received signal is processed into a predetermined format such as a digital time series. Neural networks perform

  20. 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.

  1. Mifepristone for luteal phase contraception.

    PubMed

    Croxatto, Horacio B

    2003-12-01

    The concept of luteal phase contraception and the use of mifepristone in clinical trials, which allows for testing of its validity, as well as clinical pharmacological research designed to understand its mode of action, are reviewed. Early luteal phase administration has a variety of morphological, physiological and biochemical effects on the endometrium that are likely to interfere with embryonic-endometrial interactions. In fact, specifically designed pilot clinical trials as well as data derived from emergency contraception studies indicate that early luteal phase administration of mifepristone is highly effective in preventing pregnancy, with minimal disturbance of hormonal parameters or menstrual cyclicity. Mid and late luteal phase administration of mifepristone at doses above 25 mg are highly effective in inducing endometrial bleeding in nonconceptional cycles. However, administration of mifepristone within the period between implantation and expected menses fails to induce bleeding in a significant proportion of cases, and furthermore the bleeding induced does not insure the termination of pregnancy. While the data suggest there is potential for a once-a-month contraceptive pill, it is likely that no molecule endowed with partial agonistic properties, like mifepristone, will completely and reliably suppress the essential functions of progesterone in order to achieve contraceptive efficacy comparable to that of modern contraceptive methods.

  2. 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.

  3. 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.

  4. 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)

  5. 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.

  6. 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.

  7. 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.

  8. 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)

  9. Gas phase chemistry in comets

    NASA Technical Reports Server (NTRS)

    Oppenheimer, M.

    1976-01-01

    The significance of gas phase reactions in determining the nuclear structure of comets is discussed. The sublimation of parent molecules such as H2O, CH4, CO2, and NH3 from the surface of the nucleus and their subsequent photodissociation and ionization in forming observed cometary molecular species are elaborated.

  10. 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

  11. 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.

  12. Phase synchronization of a new chaotic system

    NASA Astrophysics Data System (ADS)

    Vahedi, Shahed; Md Noorani, Mohd Salmi

    2013-09-01

    In this paper, we are going to apply phase and anti-phase synchronization on a recently studied chaotic system by the authors. The technique we employ to extract the phase at each time is EMD and we show that the corresponding intrinsic modes of the two systems are well phase locked after activating the control functions.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. Doppler phase shifting using dual, switched phase shifting devices

    NASA Technical Reports Server (NTRS)

    Gutierrez, Roman C. (Inventor)

    2002-01-01

    A system of inducing a phase shift using moving reflector elements. The moving reflectors can be moving mirrors or an acousto-optical filter. The moving reflectors oscillate i.e. the move first in a first direction and then in a second direction. Two different reflectors are used so that the light can be switched between the reflectors. During a first portion of the cycle the light is coupled to the first modulator which moves the reflector in the first direction. The second modulator is out of phase with the first modulator, and the light is switched to that second modulator during a second portion of the cycle. The second modulator is also moving in the first direction when the light is applied thereto. In this way, the light obtains a constant direction Doppler shift.

  18. Direct phasing in femtosecond nanocrystallography. II. Phase retrieval.

    PubMed

    Chen, Joe P J; Spence, John C H; Millane, Rick P

    2014-03-01

    X-ray free-electron laser diffraction patterns from protein nanocrystals provide information on the diffracted amplitudes between the Bragg reflections, offering the possibility of direct phase retrieval without the use of ancillary experimental diffraction data [Spence et al. (2011). Opt. Express, 19, 2866-2873]. The estimated continuous transform is highly noisy however [Chen et al. (2014). Acta Cryst. A70, 143-153]. This second of a series of two papers describes a data-selection strategy to ameliorate the effects of the high noise levels and the subsequent use of iterative phase-retrieval algorithms to reconstruct the electron density. Simulation results show that employing such a strategy increases the noise levels that can be tolerated.

  19. 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.

  20. Nanostructures having crystalline and amorphous phases

    DOEpatents

    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.

  1. Phase Analysis of Fringe Pattern In Shearography

    NASA Astrophysics Data System (ADS)

    Yusof, M. Y.; Abdullah, W. S. Wan

    2008-05-01

    This paper discusses the phase analysis of interference pattern from coherent light Nd:YAG 532 nm laser source. The Twyman-Green Interferometer set-up is used for generating the fringe pattern in the phase calibration. The piezoelectric transducer (PZT) is used to achieve the required phase shift of the fringe pattern. It was found that the system required 8.8 volts of out-put DC voltage to shift 2π radians phase. The accuracy of optical phase measurement of the interference pattern is analyzed by wrapped phases of three-phase stepping and four-phase stepping procedures. Comparison of the experimental phase measurement data and the theoretical phase calculations are also highlighted.

  2. 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.

  3. 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.

  4. 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.

  5. Magnetically ordered phase near transition to Bose-glass phase

    NASA Astrophysics Data System (ADS)

    Syromyatnikov, A. V.; Sizanov, A. V.

    2017-01-01

    We discuss a magnetically ordered ("superfluid") phase near quantum transition to the Bose-glass phase in a simple modeling system, a Heisenberg antiferromagnet with spatial dimension d >2 in an external magnetic field with disorder in exchange coupling constants. Our analytical consideration is based on hydrodynamic description of long-wavelength excitations. Results obtained are valid in the entire critical region near the quantum critical point (QCP), allowing us to describe a possible crossover from one critical behavior to another. We demonstrate that the system behaves in full agreement with predictions by M. P. Fisher et al. [Phys. Rev. B 40, 546 (1989), 10.1103/PhysRevB.40.546] in close vicinity to the QCP. We find as an extension to that analysis that the anomalous dimension η =2 -d and β =ν d /2 , where β and ν are critical exponents of the order parameter and the correlation length, respectively. The density of states per spin of low-energy localized excitations is found to be independent of d ("superuniversal"). We show that many recent experimental and numerical results obtained in various three-dimensional (3D) systems can be described by our formulas using percolation critical exponents. Then, it is a possibility that a percolation critical regime arises in the ordered phase in some 3D systems not very close to the QCP.

  6. Generalized phase-shifting color digital holography

    NASA Astrophysics Data System (ADS)

    Nomura, Takanori; Kawakami, Takaaki; Shinomura, Kazuma

    2016-06-01

    Two methods to apply the generalized phase-shifting digital holography to color digital holography are proposed. One is wave-splitting generalized phase-shifting color digital holography. This is realized by using a color Bayer camera. Another is multiple exposure generalized phase-shifting color digital holography. This is realized by the wavelength-dependent phase-shifting devices. Experimental results for both generalized phase-shifting color digital holography are presented to confirm the proposed methods.

  7. 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.

  8. The VLA Atmospheric Phase Interferometer

    NASA Astrophysics Data System (ADS)

    Morris, Keith

    2014-05-01

    The Atmospheric Phase Interferometer (API) is a two-element atmospheric seeing monitor located at the Very Large Array (VLA) site. The instrument measures turbulent refractive index variation through the atmosphere by examining phase differences in a satellite beacon signal detected at two (or more) antennas. With this measurement, the VLA scheduling software is able to consider atmospheric stability when determining which frequency observation to schedule next. We are in the process of extending this two-element interferometer to four elements, which will allow us to measure the turbulence in two dimensions and at multiple length scales. This thesis will look at some statistical properties of turbulence, the effects of atmospheric stability on radio interferometric observations, and discuss details of the instrument and the data that it collects. The thesis will also cover some techniques and principles of signal processing, and an analysis of some data from the instrument. The results demonstrate that other surface atmospheric variables (e.g. windspeed, water vapor pressure) show the same structure function exponent as the atmospheric phase fluctuations. In particular, the structure functions of water vapor partial pressure and wind speed show the same exponent as the phase. Though the agreement between meteorological variables and atmospheric phase is scientifically satisfying, these surface measurements are not nearly as sensitive as the API saturation phase measurement, and therefore cannot be used to schedule telescope time in its stead. What is informative about these results is that the similar structure functions for API and meteorological data are detecting reinforce the claim that both measurements represent turbulent transport, and not instrumental noise. Data from the instrument reveals that measurements are consistent with both Kolmogorov turbulence theory, and with prior observations. The API predominately measures three-dimensional isotropic

  9. Multiphase, multicomponent phase behavior prediction

    NASA Astrophysics Data System (ADS)

    Dadmohammadi, Younas

    Accurate prediction of phase behavior of fluid mixtures in the chemical industry is essential for designing and operating a multitude of processes. Reliable generalized predictions of phase equilibrium properties, such as pressure, temperature, and phase compositions offer an attractive alternative to costly and time consuming experimental measurements. The main purpose of this work was to assess the efficacy of recently generalized activity coefficient models based on binary experimental data to (a) predict binary and ternary vapor-liquid equilibrium systems, and (b) characterize liquid-liquid equilibrium systems. These studies were completed using a diverse binary VLE database consisting of 916 binary and 86 ternary systems involving 140 compounds belonging to 31 chemical classes. Specifically the following tasks were undertaken: First, a comprehensive assessment of the two common approaches (gamma-phi (gamma-ϕ) and phi-phi (ϕ-ϕ)) used for determining the phase behavior of vapor-liquid equilibrium systems is presented. Both the representation and predictive capabilities of these two approaches were examined, as delineated form internal and external consistency tests of 916 binary systems. For the purpose, the universal quasi-chemical (UNIQUAC) model and the Peng-Robinson (PR) equation of state (EOS) were used in this assessment. Second, the efficacy of recently developed generalized UNIQUAC and the nonrandom two-liquid (NRTL) for predicting multicomponent VLE systems were investigated. Third, the abilities of recently modified NRTL model (mNRTL2 and mNRTL1) to characterize liquid-liquid equilibria (LLE) phase conditions and attributes, including phase stability, miscibility, and consolute point coordinates, were assessed. The results of this work indicate that the ϕ-ϕ approach represents the binary VLE systems considered within three times the error of the gamma-ϕ approach. A similar trend was observed for the for the generalized model predictions using

  10. Asteroid photometry: Phase-angle effects

    NASA Astrophysics Data System (ADS)

    Belskaya, I.; Shevchenko, V.

    2014-07-01

    We review available observational data on magnitude phase-angle dependencies of asteroids. The number of asteroids, for which good quality phase curves were measured, increases very slowly. At present, the data-set on magnitude-phase dependencies with a good phase-angle coverage and small scatter includes less than one hundred asteroids. Most part of these data is related to the ground-based observations of main-belt asteroids and covered the phase-angle range from 0.3--0.5 deg to 20--25 deg. The phase curves in the wider phase-angle range up to 120--140 deg were measured for ten asteroids observed by space missions and for several near-Earth asteroids. Ground-based and space-based observations are generally mutually consistent. For most of the observed phase-angle ranges, asteroid magnitude phase curves are found to be linear with a noticeable deviation at phase angles smaller than 5--7 deg due to the opposition effect and at phase angles larger than 70-80 deg due to the influence of large-scale surface features. The differences in the phase curves at large phase angles and their influence on the phase integral have not yet been thoroughly investigated. The measured linear phase coefficients of asteroids are in the range of 0.02--0.05 mag/deg. The opposition-effect amplitudes determined relatively to the extrapolation of the linear part of the phase curve do not exceeds 0.4 mag. Relatively small variations of asteroid phase curve parameters require accurate photometric observations and thorough account for lightcurve amplitude to distinguish phase-angle effects. The measured magnitude phase dependencies revealed essential differences in magnitude phase-angle behavior for asteroids of different surface composition both in the linear part and in the opposition effect range (Harris et al. 1989, Belskaya and Shevchenko 2000, Shevchenko et al. 2012). Maximal amplitude of the opposition effect occurs for moderate-albedo S- and M-type asteroids. Low-albedo asteroids

  11. Fiber bundle phase conjugate mirror

    DOEpatents

    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.

  12. Phase diagram of Hertzian spheres

    NASA Astrophysics Data System (ADS)

    Pàmies, Josep C.; Cacciuto, Angelo; Frenkel, Daan

    2009-07-01

    We report the phase diagram of interpenetrating Hertzian spheres. The Hertz potential is purely repulsive, bounded at zero separation, and decreases monotonically as a power law with exponent 5/2, vanishing at the overlapping threshold. This simple functional describes the elastic interaction of weakly deformable bodies and, therefore, it is a reliable physical model of soft macromolecules, like star polymers and globular micelles. Using thermodynamic integration and extensive Monte Carlo simulations, we computed accurate free energies of the fluid phase and a large number of crystal structures. For this, we defined a general primitive unit cell that allows for the simulation of any lattice. We found multiple re-entrant melting and first-order transitions between crystals with cubic, trigonal, tetragonal, and hexagonal symmetries.

  13. Phase Aberrations in Diffraction Microscopy

    SciTech Connect

    Marchesini, S; Chapman, H N; Barty, A; Howells, M R; Spence, J H; Cui, C; Weierstall, U; Minor, A M

    2005-09-29

    In coherent X-ray diffraction microscopy the diffraction pattern generated by a sample illuminated with coherent x-rays is recorded, and a computer algorithm recovers the unmeasured phases to synthesize an image. By avoiding the use of a lens the resolution is limited, in principle, only by the largest scattering angles recorded. However, the imaging task is shifted from the experiment to the computer, and the algorithm's ability to recover meaningful images in the presence of noise and limited prior knowledge may produce aberrations in the reconstructed image. We analyze the low order aberrations produced by our phase retrieval algorithms. We present two methods to improve the accuracy and stability of reconstructions.

  14. 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.

  15. Undersampled Phase Retrieval with Outliers

    PubMed Central

    Weller, Daniel S.; Pnueli, Ayelet; Divon, Gilad; Radzyner, Ori; Eldar, Yonina C.; Fessler, Jeffrey A.

    2015-01-01

    This paper proposes a general framework for reconstructing sparse images from undersampled (squared)-magnitude data corrupted with outliers and noise. This phase retrieval method uses a layered approach, combining repeated minimization of a convex majorizer (surrogate for a nonconvex objective function), and iterative optimization of that majorizer using a preconditioned variant of the alternating direction method of multipliers (ADMM). Since phase retrieval is nonconvex, this implementation uses multiple initial majorization vectors. The introduction of a robust 1-norm data fit term that is better adapted to outliers exploits the generality of this framework. The derivation also describes a normalization scheme for the regularization parameter and a known adaptive heuristic for the ADMM penalty parameter. Both 1D Monte Carlo tests and 2D image reconstruction simulations suggest the proposed framework, with the robust data fit term, reduces the reconstruction error for data corrupted with both outliers and additive noise, relative to competing algorithms having the same total computation. PMID:26770999

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. Phase-domain photoacoustic sensing

    NASA Astrophysics Data System (ADS)

    Gao, Fei; Zhang, Ruochong; Feng, Xiaohua; Liu, Siyu; Ding, Ran; Kishor, Rahul; Qiu, Lei; Zheng, Yuanjin

    2017-01-01

    As one of the fastest-growing imaging modalities in recent years, photoacoustic imaging has attracted tremendous research interest for various applications including anatomical, functional, and molecular imaging. The majority of the photoacoustic imaging systems are based on the time-domain pulsed photoacoustic method, which utilizes a pulsed laser source to induce a wideband photoacoustic signal, revealing optical absorption contrast. An alternative way is the frequency-domain photoacoustic method utilizing the chirping modulation of laser intensity to achieve lower system cost. In this paper, we report another way of the photoacoustic method, called phase-domain photoacoustic sensing, which explores the phase difference between two consequent intensity-modulated laser pulse induced photoacoustic measurements to reveal the optical properties. The basic principle is introduced, modeled, and experimentally validated in this paper, which opens another potential pathway to perform photoacoustic sensing and imaging, eliminating acoustic detection variations beyond the conventional time-domain and frequency-domain photoacoustic methods.

  1. 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

  2. Phase Transitions in Brownian Pumps

    NASA Astrophysics Data System (ADS)

    Dierl, Marcel; Dieterich, Wolfgang; Einax, Mario; Maass, Philipp

    2014-04-01

    We study stochastic particle transport between two reservoirs along a channel, where the particles are pumped against a bias by a traveling wave potential. It is shown that phase transitions of period-averaged densities or currents occur inside the channel when exclusion interactions between the particles are taken into account. These transitions reflect those known for the asymmetric simple exclusion process. We argue that their occurrence is a generic feature of Brownian motors operating in open systems.

  3. Exotic Phases of Ultracold Atoms

    DTIC Science & Technology

    2011-11-18

    lattices". 5 10 July 2007 Henri Poincare Institute, Paris, France, Quantum Gases Program Seminar: “Some unconventional phases of cold atomic matter with or...Pittsburgh, PA. (Attended) 10. PI, Paris Program on “Quantum Gases”, Centre Emile Borel, Institut Henri Poincaré, April 23- July 20, 2007, Paris...Pittsburgh. Promoted to the rank of Associated Profes- sor, effective Sep 1, 2009. 7. Visiting Scientist, Centre Emile Borel, Institut Henri Poincaré

  4. 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.

  5. 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.

  6. 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

  7. 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.

  8. 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.

  9. 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.

  10. [Phase I cancer trials methodology].

    PubMed

    Le Tourneau, Christophe; Faivre, Sandrine; Raymond, Eric; Diéras, Véronique

    2007-11-01

    The main objective of phase I cancer trials is to determine precisely the recommended dose of an anticancer agent as a single agent or in a context of combinations of anticancer agents (including cytotoxic agents, immunotherapy, radiotherapy...), that is administered for the first time in man, to further proceed clinical development with phase II and III trials. The recommended dose must have the greatest efficiency with acceptable toxicity. For the anticancer agents, the ratio risk/benefit is high, since toxicities associated with many cancer therapeutic agents are substantial and because the efficacy is often limited. Thus, phase I cancer trials present unique challenges in comparison to other therapeutic areas. Indeed, it is essential to minimize the numbers of patients treated at subefficient dose levels, and in the same time not to expose the patients to unacceptable toxicity. Historically, the first method that has been used is the Fibonacci escalation. The major problems raised with this method have been the lengths of the trials and the risk to treat substantial numbers of patients at nontherapeutix doses. Thus, novel methods have been then developed modifying the numbers of patients included at each dose level and the rapidity of dose escalation. These methods include pharmacologically guided dose escalation, escalation with overdose control and the continual reassessment method which are both statistically based dose escalation methods, and the accelerated titration designs. Concerning the targeted anticancer therapies, the therapeutic effect on the target, due to their higher specificity, can be obtained using doses that have few toxicity. Using the toxicity to determine the recommended dose for phase II trials, as it is the case for "classical > anticancer agents, does not seem to be sufficient. Alternatives to determine the optimal biological dose include measurement of target inhibition, pharmacokinetic analysis and functional imaging.

  11. Quantum Dimer Model: Phase Diagrams

    NASA Astrophysics Data System (ADS)

    Goldstein, Garry; Chamon, Claudio; Castelnovo, Claudio

    We present new theoretical analysis of the Quantum Dimer Model. We study dimer models on square, cubic and triangular lattices and we reproduce their phase diagrams (which were previously known only numerically). We show that there are several types of dimer liquids and solids. We present preliminary analysis of several other models including doped dimers and planar spin ice, and some results on the Kagome and hexagonal lattices.

  12. Phase Behavior of Ionic Microgels

    NASA Astrophysics Data System (ADS)

    Gottwald, D.; Likos, C. N.; Kahl, G.; Löwen, H.

    2004-02-01

    We employ effective interaction potentials between spherical polyelectrolyte microgels in order to investigate theoretically the structure, thermodynamics, and phase behavior of ionic microgel solutions. Combining a genetic algorithm with accurate free energy calculations we are able to perform an unrestricted search of candidate crystal structures. Hexagonal, body-centered orthogonal, and trigonal crystals are found to be stable at high concentrations and charges of the microgels, accompanied by reentrant melting behavior and fluid-fcc-bcc transitions below the overlap concentration.

  13. Quantum shuttle in phase space.

    PubMed

    Novotný, Tomás; Donarini, Andrea; Jauho, Antti-Pekka

    2003-06-27

    We present a quantum theory of the shuttle instability in electronic transport through a nanostructure with a mechanical degree of freedom. A phase space formulation in terms of the Wigner function allows us to identify a crossover from the tunneling to the shuttling regime, thus extending the previously found classical results to the quantum domain. Further, a new dynamical regime is discovered, where the shuttling is driven exclusively by the quantum noise.

  14. Phase behavior of ionic microgels.

    PubMed

    Gottwald, D; Likos, C N; Kahl, G; Löwen, H

    2004-02-13

    We employ effective interaction potentials between spherical polyelectrolyte microgels in order to investigate theoretically the structure, thermodynamics, and phase behavior of ionic microgel solutions. Combining a genetic algorithm with accurate free energy calculations we are able to perform an unrestricted search of candidate crystal structures. Hexagonal, body-centered orthogonal, and trigonal crystals are found to be stable at high concentrations and charges of the microgels, accompanied by reentrant melting behavior and fluid-fcc-bcc transitions below the overlap concentration.

  15. Quantum gates with topological phases

    SciTech Connect

    Ionicioiu, Radu

    2003-09-01

    We investigate two models for performing topological quantum gates with the Aharonov-Bohm (AB) and Aharonov-Casher (AC) effects. Topological one- and two-qubit Abelian phases can be enacted with the AB effect using charge qubits, whereas the AC effect can be used to perform all single-qubit gates (Abelian and non-Abelian) for spin qubits. Possible experimental setups suitable for a solid-state implementation are briefly discussed.

  16. Phase diagrams for sonoluminescing bubbles

    NASA Astrophysics Data System (ADS)

    Hilgenfeldt, Sascha; Lohse, Detlef; Brenner, Michael P.

    1996-11-01

    Sound driven gas bubbles in water can emit light pulses. This phenomenon is called sonoluminescence (SL). Two different phases of single bubble SL have been proposed: diffusively stable and diffusively unstable SL. We present phase diagrams in the gas concentration versus forcing pressure state space and also in the ambient radius versus gas concentration and versus forcing pressure state spaces. These phase diagrams are based on the thresholds for energy focusing in the bubble and two kinds of instabilities, namely (i) shape instabilities and (ii) diffusive instabilities. Stable SL only occurs in a tiny parameter window of large forcing pressure amplitude Pa˜1.2-1.5 atm and low gas concentration of less than 0.4% of the saturation. The upper concentration threshold becomes smaller with increased forcing. Our results quantitatively agree with experimental results of Putterman's UCLA group on argon, but not on air. However, air bubbles and other gas mixtures can also successfully be treated in this approach if in addition (iii) chemical instabilities are considered. All statements are based on the Rayleigh-Plesset ODE approximation of the bubble dynamics, extended in an adiabatic approximation to include mass diffusion effects. This approximation is the only way to explore considerable portions of parameter space, as solving the full PDEs is numerically too expensive. Therefore, we checked the adiabatic approximation by comparison with the full numerical solution of the advection diffusion PDE and find good agreement.

  17. Spatial phase stepping wavelength meter

    NASA Astrophysics Data System (ADS)

    Surrel, Yves; García-Márquez, Jorge; Fodor, Jozsua; Juncar, Patrick

    2005-03-01

    A new way of evaluating the ratio between a reference wavelength radiation and an unknown wavelength radiation in a two-beam interferometer is proposed here. The advantage of two-beam interferometry is the sinusoidal fringe signal for which precise phase detection algorithms exist. Modern algorithms can cope with different sources of errors, and correct them. We recall the principle of the Michelson-type lambdameter using temporal interference and we introduce the Young-type lambdameter using spatial interference. The Young-type lambdameter is based on the acquisition of the interference pattern from two point sources (e.g. two ends of monomode fibres projected onto a CCD camera). The measurement of an unknown wavelength can be achieved by comparing with a reference wavelength. Accurate interference phase maps can be calculated using spatial phase shifting. In this way, each small group of contiguous pixels acts as a single interferometer, and the whole set of pixels corresponds to many hundreds or thousands of interferometric measurement system units. The analysis of uncertainties shows that resolutions better than 10-7 can be achieved. An advantage of the fibre wavelength metre described here is the measurement velocity that takes only a few seconds.

  18. Phase diagram of crushed powders

    NASA Astrophysics Data System (ADS)

    Bodard, Sébastien; Jalbaud, Olivier; Saurel, Richard; Burtschell, Yves; Lapebie, Emmanuel

    2016-12-01

    Compression of monodisperse powder samples in quasistatic conditions is addressed in a pressure range such that particles fragmentation occurs while the solid remains incompressible (typical pressure range of 1-300 MPa for glass powders). For a granular bed made of particles of given size, the existence of three stages is observed during compression and crush up. First, classical compression occurs and the pressure of the granular bed increases along a characteristic curve as the volume decreases. Then, a critical pressure is reached for which fragmentation begins. During the fragmentation process, the granular pressure stays constant in a given volume range. At the end of this second stage, 20%-50% of initial grains are reduced to finer particles, depending on the initial size. Then the compression undergoes the third stage and the pressure increases along another characteristic curve, in the absence of extra fragmentation. The present paper analyses the analogies between the phase transition in liquid-vapour systems and powder compression with crush-up. Fragmentation diagram for a soda lime glass is determined by experimental means. The analogues of the saturation pressure and latent heat of phase change are determined. Two thermodynamic models are then examined to represent the crush-up diagram. The first one uses piecewise functions while the second one is of van der Waals type. Both equations of state relate granular pressure, solid volume fraction, and initial particle diameter. The piecewise functions approach provides reasonable representations of the phase diagram while the van der Waals one fails.

  19. 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.

  20. NIF optics phase gradient specfication

    SciTech Connect

    Williams, W.; Auerbach, J.; Hunt, J.; Lawson, L.; Manes, K.; Orth, C.; Sacks, R.; Trenholme, J.; Wegner, P.

    1997-05-02

    A root-mean-square (rms) phase gradient specification seems to allow a good connection between the NIP optics quality and focal spot requirements. Measurements on Beamlet optics individually, and as a chain, indicate they meet the assumptions necessary to use this specification, and that they have a typical rms phase gradient of {approximately}80 {angstrom}/cm. This may be sufficient for NIP to meet the proposed Stockpile Stewardship Management Program (SSMP) requirements of 80% of a high- power beam within a 200-250 micron diameter spot. Uncertainties include, especially, the scale length of the optics phase noise, the ability of the adaptive optic to correct against pump-induced distortions and optics noise, and the possibility of finding mitigation techniques against whole-beam self-focusing (e.g. a pre- correction optic). Further work is needed in these areas to better determine the NIF specifications. This memo is a written summary of a presentation on this topic given by W. Williams 24 April 1997 to NIP and LS&T personnel.

  1. New 'phase' of quantum gravity.

    PubMed

    Wang, Charles H-T

    2006-12-15

    The emergence of loop quantum gravity over the past two decades has stimulated a great resurgence of interest in unifying general relativity and quantum mechanics. Among a number of appealing features of this approach is the intuitive picture of quantum geometry using spin networks and powerful mathematical tools from gauge field theory. However, the present form of loop quantum gravity suffers from a quantum ambiguity, owing to the presence of a free (Barbero-Immirzi) parameter. Following the recent progress on conformal decomposition of gravitational fields, we present a new phase space for general relativity. In addition to spin-gauge symmetry, the new phase space also incorporates conformal symmetry making the description parameter free. The Barbero-Immirzi ambiguity is shown to occur only if the conformal symmetry is gauge fixed prior to quantization. By withholding its full symmetries, the new phase space offers a promising platform for the future development of loop quantum gravity. This paper aims to provide an exposition, at a reduced technical level, of the above theoretical advances and their background developments. Further details are referred to cited references.

  2. Phase diagram of elastic spheres.

    PubMed

    Athanasopoulou, L; Ziherl, P

    2017-02-15

    Experiments show that polymeric nanoparticles often self-assemble into several non-close-packed lattices in addition to the face-centered cubic lattice. Here, we explore theoretically the possibility that the observed phase sequences may be associated with the softness of the particles, which are modeled as elastic spheres interacting upon contact. The spheres are described by two finite-deformation theories of elasticity, the modified Saint-Venant-Kirchhoff model and the neo-Hookean model. We determine the range of indentations where the repulsion between the spheres is pairwise additive and agrees with the Hertz theory. By computing the elastic energies of nine trial crystal lattices at densities far beyond the Hertzian range, we construct the phase diagram and find the face- and body-centered cubic lattices as well as the A15 lattice and the simple hexagonal lattice, with the last two being stable at large densities where the spheres are completely faceted. These results are qualitatively consistent with observations, suggesting that deformability may indeed be viewed as a generic property that determines the phase behavior in nanocolloidal suspensions.

  3. 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.

  4. 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.

  5. 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

  6. 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.

  7. A study on phase-noise reduction method in phase-locked loop systems.

    PubMed

    Takagi, Keiji

    2003-09-01

    Experimental studies are carried out on phase noise and the correlation coefficient between the phase and average current noises of voltage-controlled oscillator in phased-locked loop (PLL) systems. The precise phase stabilization technique is discussed, and new methods to reduce the phase noise are described in PLL systems, using the correlation.

  8. Laser Phase Front Measurements Using a Phase Conjugate Twyman-Green Interferometer

    DTIC Science & Technology

    1992-12-01

    34 AD-A258 821 AFIT/GEP/ENP/92-D-08 LASER PHASE FRONT MEASUREMENTS USING A PHASE CONJUGATE TWYMAN -GREEN INTERFEROMETER THESIS William J. Mandeville...LASER PHASE FRONT MEASUREMENTS USING A PHASE CONJUGATE TWYMAN -GREEN INTERFEROMETER THESIS Presented to the Faculty of the School of Engineering of the... Interferometer .............................................. 19 8. Phase conjugate Twyman -Green Interferometer .................................. 21

  9. Thermophysical properties of coexistent phases of plutonium

    SciTech Connect

    Freibert, Franz J; Mitchell, Jeremy N; Saleh, Tarik A; Schwartz, Dan S

    2009-01-01

    Plutonium is the element with the greatest number of allotropic phases. Thermally induced transformations between these phases are typically characterized by thermal hysteresis and incomplete phase reversion. With Ga substitutal in the lattice, low symmetry phases are replaced by a higher symmetry phase. However, the low temperature Martensitic phase transformation ({delta} {yields} {alpha}{prime}) in Ga stabilized {delta}-phase Pu is characterized by a region of thermal hysteresis which can reach 200 C in extent. These regions of thermal hysteresis offer a unique opportunity to study thermodynamics in inhomogeneous systems of coexistent phases. The results of thermophysical properties measured for samples of inhomogeneous unalloyed and Ga alloyed Pu will be discussed and compared with similar measurements of their single phase constituents.

  10. 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

  11. Variable phase sine wave generator for active phased arrays

    NASA Astrophysics Data System (ADS)

    Waters, W. M.

    1992-09-01

    A waveform generator is provided for generating a high frequency waveform. A pulse generator provides a pulse train at a low frequency. A pulse converter converts the pulse train into an alternatingly positive and negative groups of pulses. A bandpass filter passes the alternatingly positive and negative groups of pulses in a frequency band centered at the high frequency to output the generated waveform at the high frequency. When the groups of pulses are a pair of pulses, a sine wave is output from the bandpass filter. A pulse delay circuit can be used to variably delay the pulse train and thereby cause a phase change in the generated waveform.

  12. Quantum gates and their coexisting geometric phases

    SciTech Connect

    Wu Lianao; Bishop, C. Allen; Byrd, Mark S.

    2011-08-15

    Geometric phases arise naturally in a variety of quantum systems with observable consequences. They also arise in quantum computations when dressed states are used in gating operations. Here we show how they arise in these gating operations and how one may take advantage of the dressed states producing them. Specifically, we show that for a given, but arbitrary Hamiltonian, and at an arbitrary time {tau}, there always exists a set of dressed states such that a given gate operation can be performed by the Hamiltonian up to a phase {phi}. The phase is a sum of a dynamical phase and a geometric phase. We illustrate the dressed phase for several systems.

  13. Ponderomotive phase plate for transmission electron microscopes

    DOEpatents

    Reed, Bryan W [Livermore, CA

    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.

  14. Phase and structural transformations in magnetorheological suspensions

    NASA Astrophysics Data System (ADS)

    Iskakova, L. Yu.; Romanchuk, A. P.; Zubarev, A. Yu.

    2006-07-01

    Particle condensation in magnetorheological suspensions (MRS) under external magnetic field is studied theoretically. It is shown that the bulk condensation of particles into dense phases is preceded by the formation of fairly long chain aggregates. Phase transition occurs as a condensation of such chains due to their magnetic interaction. In thin layers of MRS, placed into the normal magnetic field, scenario of the phase transition differs essentially from that in infinite volumes of these systems. Equilibrium state of the system after the phase transition corresponds to the formation of ensemble of discrete domains of the dense phase rather than to separation into two massive phases as it takes place in infinite media.

  15. 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 )

  16. 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.

  17. 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.

  18. Parallel phase-shifting digital holography with adaptive function using phase-mode spatial light modulator.

    PubMed

    Lin, Miao; Nitta, Kouichi; Matoba, Osamu; Awatsuji, Yasuhiro

    2012-05-10

    Parallel phase-shifting digital holography using a phase-mode spatial light modulator (SLM) is proposed. The phase-mode SLM implements spatial distribution of phase retardation required in the parallel phase-shifting digital holography. This SLM can also compensate dynamically the phase distortion caused by optical elements such as beam splitters, lenses, and air fluctuation. Experimental demonstration using a static object is presented.

  19. Vapors-liquid phase separator

    NASA Astrophysics Data System (ADS)

    Frederking, T. H. K.; Brown, G. S.; Chuang, C.; Kamioka, Y.; Kim, Y. I.; Lee, J. M.; Yuan, S. W. K.

    1980-10-01

    The use of porous plugs, mostly with in the form of passive devices with constant area were considered as vapor-liquid phase separators for helium 2 storage vessels under reduced gravity. The incorporation of components with variable cross sectional area as a method of flow rate modification was also investigated. A particular device which uses a shutter-type system for area variation was designed and constructed. This system successfully permitted flor rate changes of up to plus or minus 60% from its mean value.

  20. 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.

  1. 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.

  2. 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

  3. Phase-shifting Gabor holography.

    PubMed

    Micó, Vicente; García, Javier; Zalevsky, Zeev; Javidi, Bahram

    2009-05-15

    We present a modified Gabor-like setup able to recover the complex amplitude distribution of the object wavefront from a set of inline recorded holograms. The proposed configuration is characterized by the insertion of a condenser lens and a spatial light modulator (SLM) into the classical Gabor configuration. The phase shift is introduced by the SLM that modulates the central spot (dc term) in an intermediate plane, without an additional reference beam. Experimental results validate the proposed method and produce superior results to the Gabor method.

  4. 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.

  5. 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.

  6. 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

  7. 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.

  8. 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.

  9. Automated Array Assembly, Phase 2

    NASA Technical Reports Server (NTRS)

    Carbajal, B. G.

    1979-01-01

    The Automated Array Assembly Task, Phase 2 of the Low Cost Silicon Solar Array Project is a process development task. The contract provides for the fabrication of modules from large area tandem junction cells (TJC). During this quarter, effort was focused on the design of a large area, approximately 36 sq cm, TJC and process verification runs. The large area TJC design was optimized for minimum I squared R power losses. In the TJM activity, the cell-module interfaces were defined, module substrates were formed and heat treated and clad metal interconnect strips were fabricated.

  10. 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.

  11. 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).

  12. Waveguide mutually pumped phase conjugators.

    PubMed

    James, S W; Youden, K E; Jeffrey, P M; Eason, R W; Chandler, P J; Zhang, L; Townsend, P D

    1993-09-20

    The operation of the bridge mutually pumped phase conjugator is reported in a planar waveguide structure in photorefractive BaTiO(3). The waveguide was fabricated by the technique of ion implantation, using 1.5-MeVH(+) ions at a dose of 10(16) ions/cm(2). An order of magnitude decrease in response time is observed in the waveguide as compared with typical values obtained in bulk crystals, probably as a result of a combination of the optical confinement within the waveguide and possible modification of the charge-transport properties induced by the implantation process.

  13. 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.

  14. Formation of metastable phases by spinodal decomposition

    PubMed Central

    Alert, Ricard; Tierno, Pietro; Casademunt, Jaume

    2016-01-01

    Metastable phases may be spontaneously formed from other metastable phases through nucleation. Here we demonstrate the spontaneous formation of a metastable phase from an unstable equilibrium by spinodal decomposition, which leads to a transient coexistence of stable and metastable phases. This phenomenon is generic within the recently introduced scenario of the landscape-inversion phase transitions, which we experimentally realize as a structural transition in a colloidal crystal. This transition exhibits a rich repertoire of new phase-ordering phenomena, including the coexistence of two equilibrium phases connected by two physically different interfaces. In addition, this scenario enables the control of sizes and lifetimes of metastable domains. Our findings open a new setting that broadens the fundamental understanding of phase-ordering kinetics, and yield new prospects of applications in materials science. PMID:27713406

  15. 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.

  16. 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.

  17. Low-noise phase/frequency detector

    NASA Astrophysics Data System (ADS)

    McCorkle, J. W.

    1985-09-01

    The purpose of the research reported on in this thesis, is to demonstrate the effectiveness of a new circuit technique proposed by the author to eliminate the dead-zone anomaly in a digital phase/frequency detector. In addition to demonstrating the elimination of the dead zone, a new loop filter is described. The filter takes advantage of the new phase detector circuit technique so as to simultaneously provide both low-level reference sidebands and a lock-up time of one cycle of the reference. Phase detectors are used in control systems to measure the phase of one signal relative to the phase of another signal. Control systems of this type are usually referred to as Phase-Locked-Loops (PLL). Development of phase detectors has occurred because of the PLL application. A new phase detector is described in this paper.

  18. Treating Chronic Myeloid Leukemia by Phase

    MedlinePlus

    ... CML) Treating Chronic Myeloid Leukemia Treating Chronic Myeloid Leukemia by Phase Treatment options for people with chronic ... Myeloid Leukemia by Phase More In Chronic Myeloid Leukemia About Chronic Myeloid Leukemia Causes, Risk Factors, and ...

  19. Formation of metastable phases by spinodal decomposition

    NASA Astrophysics Data System (ADS)

    Alert, Ricard; Tierno, Pietro; Casademunt, Jaume

    2016-10-01

    Metastable phases may be spontaneously formed from other metastable phases through nucleation. Here we demonstrate the spontaneous formation of a metastable phase from an unstable equilibrium by spinodal decomposition, which leads to a transient coexistence of stable and metastable phases. This phenomenon is generic within the recently introduced scenario of the landscape-inversion phase transitions, which we experimentally realize as a structural transition in a colloidal crystal. This transition exhibits a rich repertoire of new phase-ordering phenomena, including the coexistence of two equilibrium phases connected by two physically different interfaces. In addition, this scenario enables the control of sizes and lifetimes of metastable domains. Our findings open a new setting that broadens the fundamental understanding of phase-ordering kinetics, and yield new prospects of applications in materials science.

  20. 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.

  1. Phase sorting wave-particle correlator

    NASA Astrophysics Data System (ADS)

    Kletzing, C. A.; LaBelle, J.; Bounds, S. R.; Dolan, J.; Kaeppler, S. R.; Dombrowski, M.

    2017-02-01

    Wave-particle correlations, particularly of Langmuir waves and electrons, have been the subject of significant interest extending back to the 1970s. Often, these correlations have been simply observing modulation of the electrons at the plasma frequency with no phase resolution. The first phase-resolving correlators were developed at UC Berkeley in the late 1980s and reported by Ergun in the early 1990s. A design is presented which further improves on phase resolution in correlations of Langmuir waves and electrons with phase resolution of 22.5°. In this technique, a phase-locked loop (PLL) is used to lock onto the wave and subdivide the phase. Electrons are sorted on-the-fly as they arrive into the phase bins. Discussed are details of accurate timing, testing, and calibration of this system as well as results from rocket flights in which statistically significant phase correlations have been observed.

  2. Digital phase conjugate mirror by parallel arrangement of two phase-only spatial light modulators.

    PubMed

    Shibukawa, Atsushi; Okamoto, Atsushi; Goto, Yuta; Honma, Satoshi; Tomita, Akihisa

    2014-05-19

    In a conventional digital phase conjugation system, only the phase of an input light is time-reversed. This deteriorates phase conjugation fidelity and restricts application fields to specific cases only when the input light has uniformly-distributed scattered wavefront. To overcome these difficulties, we present a digital phase conjugate mirror based on parallel alignment of two phase-only spatial light modulators (SLMs), in which both amplitude and phase of the input light can be time-reversed. Experimental result showed that, in the phase conjugation through a holographic diffuser with diffusion angle of 0.5 degree, background noises decrease to 65% by our digital phase conjugation mirror.

  3. 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.

  4. 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.

  5. 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.

  6. Predicting the CP-Phase for Neutrinos

    NASA Astrophysics Data System (ADS)

    Takasugi, Eiichi

    In view of recent observation of neutrino mixing angles and also the CP-phase, the model to predict the CP phase becomes more interesting. In 2000, we proposed the neutrino mass matrix that predicts the maximal CP violation and the 2-3 mixing angle. I revisit this model and explore this model further to investigate Majorana phases and the possible extension that allows the deviation of the CP phase and the 2-3 mixing from the maximal.

  7. Phase protection system for ac power lines

    NASA Technical Reports Server (NTRS)

    Wong, W. J. (Inventor)

    1974-01-01

    The system described provides protection for phase sensitive loads from being or remaining connected to ac power lines whenever a phase reversal occurs. It comprises a solid state phase detection circuit, a dc power relay circuit, an ac-to-dc converter for energizing the relay circuit, and a bistable four terminal transducer coupled between the phase detection circuit and the power relay circuit, for controlling both circuits.

  8. 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.

  9. Sarcopenia: designing phase IIB trials.

    PubMed

    Chumlea, Wm C; Cesari, M; Evans, W J; Ferrucci, L; Fielding, R A; Pahor, M; Studenski, S; Vellas, B

    2011-06-01

    Sarcopenia is the age-related involuntary loss of skeletal muscle mass and functionality that can lead to the development of disability, frailty and increased health care costs. The development of interventions aimed at preventing and/or treating sarcopenia is complex, requiring the adoption of assumptions and standards that are not well established scientifically or clinically. A number of investigators and clinicians (both from academia and industry) met in Rome (Italy) in 2009 to develop a consensus definition of sarcopenia. Subsequently, in Albuquerque (New Mexico, USA) in 2010, the same group met again to consider the complex issues necessary for designing Phase II clinical trials for sarcopenia. Current clinical trial data indicate that fat-free mass (FFM) parameters are responsive to physical activity/nutritional treatment modalities over short time periods, but pharmacological trials of sarcopenia have yet to show significant efficacy. In order to conduct a clinical trial within a reasonable time frame, groups that model or display accelerated aging and loss of FFM are necessary. Few studies have used acceptable designs for testing treatment effects, sample sizes or primary outcomes that could provide interpretable findings or effects across studies. Dual energy x-ray absorptiometry (DXA) is the measure of choice for assessing FFM, but sufficient time is needed for changes to be detected accurately and reliably. A tool set that would allow clinical, basic and epidemiological research on sarcopenia to advance rapidly toward diagnosis and treatment phases should be those reflecting function and strength.

  10. High stability buffered phase comparator

    NASA Technical Reports Server (NTRS)

    Adams, W. A.; Reinhardt, V. S. (Inventor)

    1984-01-01

    A low noise RF signal phase comparator comprised of two high stability driver buffer amplifiers driving a double balanced mixer which operate to generate a beat frequency between the two RF input signals coupled to the amplifiers from the RF sources is described. The beat frequency output from the mixer is applied to a low noise zero crossing detector which is the phase difference between the two RF inputs. Temperature stability is provided by mounting the amplifiers and mixer on a common circuit board with the active circuit elements located on one side of a circuit board and the passive circuit elements located on the opposite side. A common heat sink is located adjacent the circuit board. The active circuit elements are embedded into the bores of the heat sink which slows the effect of ambient temperature changes and reduces the temperature gradients between the active circuit elements, thus improving the cancellation of temperature effects. The two amplifiers include individual voltage regulators, which increases RF isolation.

  11. Availability program: Phase I report

    SciTech Connect

    Thomson, S.L.; Dabiri, A.; Keeton, D.C.; Riemer, B.W.; Waganer, L.M.

    1985-05-01

    An Availability Working Group was formed within the Office of Fusion Energy in March 1984 to consider the establishment of an availability program for magnetic fusion. The scope of this program is defined to include the development of (1) a comprehensive data base, (2) empirical correlations, and (3) analytical methods for application to fusion facilities and devices. The long-term goal of the availability program is to develop a validated, integrated methodology that will provide (1) projections of plant availability and (2) input to design decisions on maintainability and system reliability requirements. The Phase I study group was commissioned to assess the status of work in progress that is relevant to the availability program. The scope of Phase I included surveys of existing data and data collection programs at operating fusion research facilities, the assessment of existing computer models to calculate system availability, and the review of methods to predict and correlate data on component failure and maintenance. The results of these investigations are reported to the Availability Working Group in this document.

  12. Three phase AC motor controller

    DOEpatents

    Vuckovich, Michael; Wright, Maynard K.; Burkett, John P.

    1984-03-20

    A motor controller for a three phase AC motor (10) which is adapted to operate bidirectionally from signals received either from a computer (30) or a manual control (32). The controller is comprised of digital logic circuit means which implement a forward and reverse command signal channel (27, 29) for the application of power through the forward and reverse power switching relays (16, 18, 20, 22). The digital logic elements are cross coupled to prevent activation of both channels simultaneously and each includes a plugging circuit (65, 67) for stopping the motor upon the removal of control signal applied to one of the two channels (27, 29) for a direction of rotation desired. Each plugging circuit (65, 67) includes a one-shot pulse signal generator (88, 102) which outputs a single pulse signal of predetermined pulsewidth which is adapted to inhibit further operation of the application of power in the channel which is being activated and to apply a reversal command signal to the other channel which provides a reversed phase application of power to the motor for a period defined by the pulse-width output of the one-shot signal generator to plug the motor (10) which will then be inoperative until another rotational command signal is applied to either of the two channels.

  13. Diffraction Techniques for Nonlamellar Phases of Phospholipids

    SciTech Connect

    Ding,L.; Liu, W.; Wang, W.; Glinka, C.; Worchester, D.; Yang, L.; Huang, H.

    2004-01-01

    A neutron diffraction method applicable to nonlamellar phases of substrate-supported lipid membranes is described and validated. When prepared on a flat substrate, the resulting nonlamellar phases have layered symmetry which provides some advantages over powder diffraction for detailed structure determination. This approach recently led to the detection of a rhombohedral phase and a distorted hexagonal phase of lipids. Here the determination of intensity and phase information for such phases is demonstrated by application to the hexagonal phase of diphytanoyl phosphatidylcholine (DPhPC). The hexagonal symmetry is used to verify the data reduction procedure for the intensities of the diffraction peaks. Diffraction intensities measured while varying the D2O/H2O ratio in the relative humidity was used to solve the phase problem. The neutron scattering length density distribution of the hexagonal phase was constructed and analyzed to elucidate the packing of the lipid molecules. The structure of DPhPC in the hexagonal phase is of interest in connection with its stalk structure in the rhombohedral phase. We also found that the incorporation of tetradecane into the DPhPC hexagonal phase is limited, similar to the case for dioleoyl phosphatidylethanolamine.

  14. Differential Phase Mode with the Keck Interferometer

    NASA Technical Reports Server (NTRS)

    Akeson, Rachel; Swain, Mark

    2000-01-01

    We describe the differential phase mode of the Keck Interferometer. The scientific goal of this mode is the direct detection and spectroscopic characterization of hot, Jupiter mass planets. We describe the differential phase effect, the basic observational mode, and the expected differential phase signatures for the extrasolar planets discovered through radial velocity searches.

  15. Geology of the Phase II System

    SciTech Connect

    Laney, R.; Laughlin, A. William

    1980-11-19

    This is a report on the analysis of EE-2 cuttings and thin sections, geologic characterization of the Phase II system, comparison with Phase 1, and geologic speculations and recommendations concerning Phase II. The EE-2 litholog has been included in the pocket.

  16. 32 CFR 651.49 - Preliminary phase.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 32 National Defense 4 2011-07-01 2011-07-01 false Preliminary phase. 651.49 Section 651.49... Preliminary phase. In the preliminary phase, the proponent agency or office identifies, as early as possible... tentative list of the affected parties to be notified. A key part of this preliminary identification is...

  17. A general formalism for phase space calculations

    NASA Technical Reports Server (NTRS)

    Norbury, John W.; Deutchman, Philip A.; Townsend, Lawrence W.; Cucinotta, Francis A.

    1988-01-01

    General formulas for calculating the interactions of galactic cosmic rays with target nuclei are presented. Methods for calculating the appropriate normalization volume elements and phase space factors are presented. Particular emphasis is placed on obtaining correct phase space factors for 2-, and 3-body final states. Calculations for both Lorentz-invariant and noninvariant phase space are presented.

  18. 45 CFR 800.104 - Phased expansion.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 45 Public Welfare 3 2014-10-01 2014-10-01 false Phased expansion. 800.104 Section 800.104 Public Welfare Regulations Relating to Public Welfare (Continued) OFFICE OF PERSONNEL MANAGEMENT MULTI-STATE PLAN PROGRAM Multi-State Plan Program Issuer Requirements § 800.104 Phased expansion. (a) Phase-in. OPM...

  19. 45 CFR 800.104 - Phased expansion.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 45 Public Welfare 3 2013-10-01 2013-10-01 false Phased expansion. 800.104 Section 800.104 Public Welfare Regulations Relating to Public Welfare (Continued) OFFICE OF PERSONNEL MANAGEMENT MULTI-STATE PLAN PROGRAM Multi-State Plan Program Issuer Requirements § 800.104 Phased expansion. (a) Phase-in. OPM...

  20. Wideband Phase-Locked Angle Modulator

    NASA Technical Reports Server (NTRS)

    Nguyen, Lim

    1991-01-01

    Modified configuration for phase-locked angle modulator circuit makes possible to design filters in modulating portion of circuit independently of filter in phase-locked-loop portion. Bandwidth of phase- or frequency-modulated output not limited by low-pass nature of loop filter.

  1. Centrifuge workers study. Phase II, completion report

    SciTech Connect

    Wooten, H.D.

    1994-09-01

    Phase II of the Centrifuge Workers Study was a follow-up to the Phase I efforts. The Phase I results had indicated a higher risk than expected among centrifuge workers for developing bladder cancer when compared with the risk in the general population for developing this same type of cancer. However, no specific agent could be identified as the causative agent for these bladder cancers. As the Phase II Report states, Phase I had been limited to workers who had the greatest potential for exposure to substances used in the centrifuge process. Phase II was designed to expand the survey to evaluate the health of all employees who had ever worked in Centrifuge Program Departments 1330-1339 but who had not been interviewed in Phase I. Employees in analytical laboratories and maintenance departments who provided support services for the Centrifuge Program were also included in Phase II. In December 1989, the Oak Ridge Associated Universities (ORAU), now known as Oak Ridge Institute for Science and Education (ORISE), was contracted to conduct a follow-up study (Phase II). Phase H of the Centrifuge Workers Study expanded the survey to include all former centrifuge workers who were not included in Phase I. ORISE was chosen because they had performed the Phase I tasks and summarized the corresponding survey data therefrom.

  2. Phase-contrast scanning transmission electron microscopy.

    PubMed

    Minoda, Hiroki; Tamai, Takayuki; Iijima, Hirofumi; Hosokawa, Fumio; Kondo, Yukihito

    2015-06-01

    This report introduces the first results obtained using phase-contrast scanning transmission electron microscopy (P-STEM). A carbon-film phase plate (PP) with a small center hole is placed in the condenser aperture plane so that a phase shift is introduced in the incident electron waves except those passing through the center hole. A cosine-type phase-contrast transfer function emerges when the phase-shifted scattered waves interfere with the non-phase-shifted unscattered waves, which passed through the center hole before incidence onto the specimen. The phase contrast resulting in P-STEM is optically identical to that in phase-contrast transmission electron microscopy that is used to provide high contrast for weak phase objects. Therefore, the use of PPs can enhance the phase contrast of the STEM images of specimens in principle. The phase shift resulting from the PP, whose thickness corresponds to a phase shift of π, has been confirmed using interference fringes displayed in the Ronchigram of a silicon single crystal specimen. The interference fringes were found to abruptly shift at the edge of the PP hole by π.

  3. Phase stability in metallic multilayers

    NASA Astrophysics Data System (ADS)

    Genc, Arda

    this problem has been solved by the correction of the spherical aberration of the microscope using a set of non-round lenses and consequently the information limit in an aberration corrected microscope (<0.1nm) has been pushed beyond an uncorrected microscope (˜0.13nm). In 2007, such a corrector system in the probe-forming lens of a Scanning TEM microscope was successfully installed at The Ohio State University. The preliminary results from this microscope were presented in the content of this work where we have studied the microscope and performed first hand experiments. Finally we have addressed the phase stability in Cu/Nb and Ti/Nb nanoscale metallic multilayers by extensive use of these advance characterization techniques and tools. At reduced layer thickness (<2nm) the change in fcc to bcc phase in Cu and hcp to bcc phase in Ti were experimentally confirmed using X-ray diffraction electron diffraction and electron imaging techniques along the plan-view and cross-section directions. These structural transformations were often referred to as being thermodynamic in nature and a classical thermodynamical model explains and predicts the formation of such pseudomorphic phases through the competition of volumetric and interfacial free energy variables. We have investigated both the structural and chemical changes in the Cu/Nb and Ti/Nb nanoscale metallic mutilayers as a function of length scale in order to understand and predict the phase stability. The important constituents: volumetric free energy and interfacial energy changes were experimentally derived considering the chemistry and structure of the multilayers and competition between these thermodynamic terms well explains the observed structural changes in nanoscale metallic multilayers.

  4. Phase saddles in light beams

    NASA Astrophysics Data System (ADS)

    Nye, J. F.

    2011-07-01

    In a section through a monochromatic light beam the contour map of phase contains saddle points. It has already been shown that a two-dimensional model of two superposed coaxial Gaussian beams, in antiphase and having different waist sizes, contains two saddles that perform an elaborate dance as the ratio of the amplitudes of the beams is altered. The present paper explains why this choreography is qualitatively identical to that found in a symmetrical version of an earlier and simpler two-dimensional model, where a plane wave is modulated by a quadratic polynomial. If wavefronts are defined as lines of equal phase, successive wavefronts pinch together in these models, and change their connectedness as they pass through two fixed saddle points on the axis. Although the idea of a phase saddle is not generally applicable in three dimensions, it can be extended to three dimensions in axially symmetric models, for example, two superposed coaxial Gaussian beams. The saddles are features of the set of azimuthal planes, and can either form rings around the axis or be on the axis itself. The action here as a parameter changes takes a more dramatic form, because it involves both a vortex ring and two saddle points on the axis, which collide and explode into a concentric saddle ring. The physical significance of saddles is that they change the topology of the wavefronts. In two dimensions a moving wavefront line passing through a fixed saddle point on the axis undergoes reconnection. As it meets an off-axis saddle the same process occurs but in a different orientation. In three dimensions as a wavefront passes through a saddle point on the axis, its local form changes from a hyperboloid of two sheets to a hyperboloid of one sheet, or vice versa, via a cone of angle 2\\tan^{-1}\\sqrt 2=109^{\\circ } . As it passes through a saddle ring a similar transition occurs simultaneously at all points of the ring. The changes in the topology of a wavefront as it encounters a monkey

  5. Supersolid phases in the magnetic fields

    NASA Astrophysics Data System (ADS)

    Wang, Ji-Guo; Yang, Shi-Jie

    2017-02-01

    We study the ground state phases of the ultracold atomic condensates loaded in a two-dimensional optical lattice with the magnetic fields. Apart from uniform superfluid (SF) phase, four types of supersolid (SS) phases in the presence of the uniform magnetic fluxes and two types of SS phases in the presence of the staggered magnetic fluxes are found. For the system without magnetic flux, except for a certain unit phase factor ϕ x (y) = π, the magnetic field has no effect on the system.

  6. Frequency spectrum analyzer with phase-lock

    DOEpatents

    Boland, Thomas J.

    1984-01-01

    A frequency-spectrum analyzer with phase-lock for analyzing the frequency and amplitude of an input signal is comprised of a voltage controlled oscillator (VCO) which is driven by a ramp generator, and a phase error detector circuit. The phase error detector circuit measures the difference in phase between the VCO and the input signal, and drives the VCO locking it in phase momentarily with the input signal. The input signal and the output of the VCO are fed into a correlator which transfers the input signal to a frequency domain, while providing an accurate absolute amplitude measurement of each frequency component of the input signal.

  7. Phase and amplitude errors in FM radars

    NASA Astrophysics Data System (ADS)

    Griffiths, Hugh D.

    The constraints on phase and amplitude errors are determined for various types of FM radar by calculating the range sidelobe levels on the point target response due to the phase and amplitude modulation of the target echo. It is shown that under certain circumstances the constraints on phase linearity appropriate for conventional pulse compression radars are unnecessarily stringent, and quite large phase errors can be tolerated provided the relative delay of the local oscillator with respect to the target echo is small compared with the periodicity of the phase error characteristic. The constraints on amplitude flatness, however, are severe under almost all circumstances.

  8. Lipid Bilayers: Clusters, Domains and Phases

    PubMed Central

    Ackerman, David G.; Feigenson, Gerald W.

    2015-01-01

    In this chapter we discuss the complex mixing behavior of plasma membrane lipids. To do so, we first introduce the plasma membrane and membrane mixtures often used to model its complexity. We then discuss the nature of lipid phase behavior in bilayers and the distinction between these phases and other manifestations of nonrandom mixing found in one-phase mixtures, such as clusters, micelles, and microemulsions. Finally, we demonstrate the applicability of Gibbs phase diagrams to the study of increasingly complex model membrane systems, with a focus on phase coexistence, morphology and their implications for the cell plasma membrane. PMID:25658342

  9. Work and quantum phase transitions: quantum latency.

    PubMed

    Mascarenhas, E; Bragança, H; Dorner, R; França Santos, M; Vedral, V; Modi, K; Goold, J

    2014-06-01

    We study the physics of quantum phase transitions from the perspective of nonequilibrium thermodynamics. For first-order quantum phase transitions, we find that the average work done per quench in crossing the critical point is discontinuous. This leads us to introduce the quantum latent work in analogy with the classical latent heat of first order classical phase transitions. For second order quantum phase transitions the irreversible work is closely related to the fidelity susceptibility for weak sudden quenches of the system Hamiltonian. We demonstrate our ideas with numerical simulations of first, second, and infinite order phase transitions in various spin chain models.

  10. Binary Colloidal Alloy Test-5: Phase Separation

    NASA Technical Reports Server (NTRS)

    Lynch, Matthew; Weitz, David A.; Lu, Peter J.

    2008-01-01

    The Binary Colloidal Alloy Test - 5: Phase Separation (BCAT-5-PhaseSep) experiment will photograph initially randomized colloidal samples onboard the ISS to determine their resulting structure over time. This allows the scientists to capture the kinetics (evolution) of their samples, as well as the final equilibrium state of each sample. BCAT-5-PhaseSep studies collapse (phase separation rates that impact product shelf-life); in microgravity the physics of collapse is not masked by being reduced to a simple top and bottom phase as it is on Earth.

  11. Sliding Over a Phase Transition

    NASA Astrophysics Data System (ADS)

    Tosatti, Erio; Benassi, Andrea; Vanossi, Andrea; Santoro, Giuseppe E.

    2011-03-01

    The frictional response experienced by a stick-slip slider when a phase transition occurs in the underlying solid substrate is a potentially exciting, poorly explored problem. We show, based on 2-dimensional simulations modeling the sliding of a nanotip, that indeed friction may be heavily affected by a continuous structural transition. First, friction turns nonmonotonic as temperature crosses the transition, peaking at the critical temperature Tc where fluctuations are strongest. Second, below Tc friction depends upon order parameter directions, and is much larger for those where the frictional slip can cause a local flip. This may open a route towards control of atomic scale friction by switching the order parameter direction by an external field or strain, with possible application to e.g., displacive ferroelectrics such as BaTi O3 , as well as ferro- and antiferro-distortive materials. Supported by project ESF FANAS/AFRI sponsored by the Italian Research Council (CNR).

  12. Iterative phase retrieval without support.

    PubMed

    Wu, J S; Weierstall, U; Spence, J C H; Koch, C T

    2004-12-01

    An iterative phase retrieval method for nonperiodic objects has been developed from the charge-flipping algorithm proposed in crystallography. A combination of the hybrid input-output (HIO) algorithm and the flipping algorithm has greatly improved performance. In this combined algorithm the flipping algorithm serves to find the support (object boundary) dynamically, and the HIO part improves convergence and moves the algorithm out of local minima. It starts with a single intensity measurement in the Fourier domain and does not require a priori knowledge of the support in the image domain. This method is suitable for general image recovery from oversampled diffuse elastic x-ray and electron-diffraction intensities. The relationship between this algorithm and the output-output algorithm is elucidated.

  13. Iterative phase retrieval without support

    NASA Astrophysics Data System (ADS)

    Wu, J. S.; Weierstall, U.; Spence, J. C. H.; Koch, C. T.

    2004-12-01

    An iterative phase retrieval method for nonperiodic objects has been developed from the charge-flipping algorithm proposed in crystallography. A combination of the hybrid input-output (HIO) algorithm and the flipping algorithm has greatly improved performance. In this combined algorithm the flipping algorithm serves to find the support (object boundary) dynamically, and the HIO part improves convergence and moves the algorithm out of local minima. It starts with a single intensity measurement in the Fourier domain and does not require a priori knowledge of the support in the image domain. This method is suitable for general image recovery from oversampled diffuse elastic x-ray and electron-diffraction intensities. The relationship between this algorithm and the output-output algorithm is elucidated.

  14. Optical phased-array ladar.

    PubMed

    Montoya, Juan; Sanchez-Rubio, Antonio; Hatch, Robert; Payson, Harold

    2014-11-01

    We demonstrate a ladar with 0.5 m class range resolution obtained by integrating a continuous-wave optical phased-array transmitter with a Geiger-mode avalanche photodiode receiver array. In contrast with conventional ladar systems, an array of continuous-wave sources is used to effectively pulse illuminate a target by electro-optically steering far-field fringes. From the reference frame of a point in the far field, a steered fringe appears as a pulse. Range information is thus obtained by measuring the arrival time of a pulse return from a target to a receiver pixel. This ladar system offers a number of benefits, including broad spectral coverage, high efficiency, small size, power scalability, and versatility.

  15. Two-phase viscoelastic jetting

    SciTech Connect

    Yu, J-D; Sakai, S.; Sethian, J.A.

    2008-12-10

    A coupled finite difference algorithm on rectangular grids is developed for viscoelastic ink ejection simulations. The ink is modeled by the Oldroyd-B viscoelastic fluid model. The coupled algorithm seamlessly incorporates several things: (1) a coupled level set-projection method for incompressible immiscible two-phase fluid flows; (2) a higher-order Godunov type algorithm for the convection terms in the momentum and level set equations; (3) a simple first-order upwind algorithm for the convection term in the viscoelastic stress equations; (4) central difference approximations for viscosity, surface tension, and upper-convected derivative terms; and (5) an equivalent circuit model to calculate the inflow pressure (or flow rate) from dynamic voltage.

  16. Liquid phase chromatography on microchips.

    PubMed

    Kutter, Jörg P

    2012-01-20

    Over the past twenty years, the field of microfluidics has emerged providing one of the main enabling technologies to realize miniaturized chemical analysis systems, often referred to as micro-Total Analysis Systems (uTAS), or, more generally, Lab-on-a-Chip Systems (LOC) [1,2]. While microfluidics was driven forward a lot from the engineering side, especially with respect to ink jet and dispensing technology, the initial push and interest from the analytical chemistry community was through the desire to develop miniaturized sensors, detectors, and, very early on, separation systems. The initial almost explosive development of, in particular, chromatographic separation systems on microchips, has, however, slowed down in recent years. This review takes a closer, critical look at how liquid phase chromatography has been implemented in miniaturized formats over the past several years, what is important to keep in mind when developing or working with separations in a miniaturized format, and what challenges and pitfalls remain.

  17. Cloud regimes as phase transitions

    NASA Astrophysics Data System (ADS)

    Stechmann, Samuel N.; Hottovy, Scott

    2016-06-01

    Clouds are repeatedly identified as a leading source of uncertainty in future climate predictions. Of particular importance are stratocumulus clouds, which can appear as either (i) closed cells that reflect solar radiation back to space or (ii) open cells that allow solar radiation to reach the Earth's surface. Here we show that these clouds regimes -- open versus closed cells -- fit the paradigm of a phase transition. In addition, this paradigm characterizes pockets of open cells as the interface between the open- and closed-cell regimes, and it identifies shallow cumulus clouds as a regime of higher variability. This behavior can be understood using an idealized model for the dynamics of atmospheric water as a stochastic diffusion process. With this new conceptual viewpoint, ideas from statistical mechanics could potentially be used for understanding uncertainties related to clouds in the climate system and climate predictions.

  18. Adaptive ground implemented phase array

    NASA Technical Reports Server (NTRS)

    Spearing, R. E.

    1973-01-01

    The simulation of an adaptive ground implemented phased array of five antenna elements is reported for a very high frequency system design that is tolerant to the radio frequency interference environment encountered by a tracking data relay satellite. Signals originating from satellites are received by the VHF ring array and both horizontal and vertical polarizations from each of the five elements are multiplexed and transmitted down to ground station. A panel on the transmitting end of the simulation chamber contains up to 10 S-band RFI sources along with the desired signal to simulate the dynamic relationship between user and TDRS. The 10 input channels are summed, and desired and interference signals are separated and corrected until the resultant sum signal-to-interference ratio is maximized. Testing performed with this simulation equipment demonstrates good correlation between predicted and actual results.

  19. Heliogyro Preliminary Design, Phase 2

    NASA Technical Reports Server (NTRS)

    1978-01-01

    There are 12 blades in the Heliogyro design, and each blade is envisioned to be 8 meters in width and 7,500 meters in length. The blades are expected to be composed primarily of a thin membrane constructed of material such as Kapton film with an aluminum reflective coating on one side and an infrared emissive coating on the other. The present Phase 2 Final Report covers work done on the following six topics: (1) Design and analysis of a stowable circular lattice batten for the Heliogyro blade. (2) Design and analysis of a biaxially tensioned blade panel. (3) Definition of a research program for micrometeoroid damage to tendons. (4) A conceptual design for a flight test model of the Heliogyro. (5) Definition of modifications to the NASTRAN computer program required to provide improved analysis of the Heliogyro. (6) A User's Manual covering applications of NASTRAN to the Heliogyro.

  20. Boost-phase discrimination research

    NASA Technical Reports Server (NTRS)

    Langhoff, Stephen R.; Feiereisen, William J.

    1993-01-01

    The final report describes the combined work of the Computational Chemistry and Aerothermodynamics branches within the Thermosciences Division at NASA Ames Research Center directed at understanding the signatures of shock-heated air. Considerable progress was made in determining accurate transition probabilities for the important band systems of NO that account for much of the emission in the ultraviolet region. Research carried out under this project showed that in order to reproduce the observed radiation from the bow shock region of missiles in their boost phase it is necessary to include the Burnett terms in the constituent equation, account for the non-Boltzmann energy distribution, correctly model the NO formation and rotational excitation process, and use accurate transition probabilities for the NO band systems. This work resulted in significant improvements in the computer code NEQAIR that models both the radiation and fluid dynamics in the shock region.