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  • 2000-2004  (1,000)
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  • 1
    Publication Date: 2001-01-01
    Print ISSN: 1077-260X
    Electronic ISSN: 1558-4542
    Topics: Electrical Engineering, Measurement and Control Technology
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  • 2
    Publication Date: 2019-07-10
    Description: Open loop, experimental force and power measurements of a three-axis, radial, heteropolar magnetic bearing at room temperature for rotor speeds up to 20,000 RPM are presented in this paper. The bearing, NASA Glenn Research Center's and Texas A&M's third generation high temperature magnetic bearing, was designed to operate in a 1000 F (540 C) environment and was primarily optimized for maximum load capacity. The experimentally measured force produced by one C-core of this bearing was 630 lb. (2.8 kN) at 16 A, while a load of 650 lbs (2.89 kN) was predicted at 16 A using 1D circuit analysis. The maximum predicted radial load for one of the three axes is 1,440 lbs (6.41 kN) at room temperature. The maximum measured load of an axis was 1050 lbs. (4.73 kN). Results of test under rotating conditions showed that rotor speed has a negligible effect on the bearing's load capacity. A single C-core required approximately 70 W of power to generate 300 lb (1.34 kN) of magnetic force. The room temperature data presented was measured after three thermal cycles up to 1000 F (540 C), totaling six hours at elevated temperatures.
    Keywords: Aircraft Propulsion and Power
    Type: NASA/TM-2002-211904 , NAS 1.15:211904 , ARL-TR-2858 , E-13594
    Format: application/pdf
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  • 3
    Publication Date: 2019-07-13
    Description: Open loop, experimental force and power measurements of a radial, redundant-axis, magnetic bearing at temperatures to 1000 F (538 C) and rotor speeds to 15,000 RPM along with theoretical temperature and force models are presented in this paper. The experimentally measured force produced by a single C-core using 22A was 600 lb. (2.67 kN) at room temperature and 380 lb. (1.69 kN) at 1000 F (538 C). These values were compared with force predictions based on a 1D magnetic circuit analysis and a thermal analysis of gap growth as a function of temperature. Tests under rotating conditions showed that rotor speed has a negligible effect on the bearing s load capacity. One C-core required approximately 340 W of power to generate 190 lb. (8.45 kN) of magnetic force at 1000 F (538 C); however the magnetic air gap was much larger than at room temperature. The data presented is after the bearing had already operated six thermal cycles and eleven total (not consecutive) hours at 1000 F (538 C).
    Keywords: Aircraft Propulsion and Power
    Type: NASA/TM-2003-212183 , E-13784 , NAS 1.15:212183 , ARL-TR-2929 , 59th Annual Forum and Technology Display; May 06, 2003 - May 08, 2003; Phoenix, AZ; United States
    Format: application/pdf
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Accreditation and quality assurance 5 (2000), S. 363-366 
    ISSN: 1432-0517
    Keywords: Key words Quality assessment ; Bias ; Harmonization ; Calibration ; Laboratory medicine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract  Most efforts in quality control have been focussed on the reduction of intralaboratory variation and the assessment of interlaboratory variation. Over the last few years, the importance of bias in interlaboratory variation and intralaboratory shifts has become clear. Small shifts can sometimes have a large impact on the number of treated patients, particularly in assays where cut off values are used. For example in cholesterol, HDL-cholesterol, HbA1c and TSH assays. There is an obvious need for adequate calibration material. However, the process of development of international primary reference materials and reference methods takes time, and even if reference materials exist and are used by in vitro diagnostics manufacturers, there still remains significant and clinically relevant interlaboratory variance and intralaboratory shifts, as is seen, e.g. in protein chemistry. The harmonization of inter laboratory and intralaboratory results needs an impulse from professional organizations to convince individual laboratories of the importance and significance of bias. This applies to all subdisciplines of laboratory medicine. On the occasion of the 25th anniversary of the Foundation for External Quality Assessment (SKZL), a large interdisciplinary harmonization project called Calibration 2000 was launched in The Netherlands The strategy and first results are reported in this paper. The project aims at harmonization of laboratory data of several disciplines, using secondary calibration materials, leading to common reference ranges throughout The Netherlands.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. Cre recombinase was used to mediate recombination between a chromosomally introduced loxP sequence in Arabidopsis thaliana (35S-lox-cre) and transferred DNA (T-DNA) originating from Agrobacterium tumefaciens (plox-npt), carrying a single loxP sequence. Constructs were designed for specific Cre-mediated recombination between the two lox sites, resulting in restoration of neomycin phosphotransferase (nptII) expression at the target locus. Kanamycin resistant (Kmr) recombinants were obtained with an efficiency of about 1% compared with random integration. Molecular analyses confirmed that these were indeed due to recombination between the lox sites of the target and introduced T-DNA. However, polymerase chain reaction analysis revealed that these reflected site-specific integration events only in a minority (4%). The other events were classified as translocations/inversions (71%) or deletions (25%), and were probably caused by site-specific recombination between a randomly integrated T-DNA and the original target locus. We studied some of these events in detail, including a Cre-mediated balanced translocation event, which was characterized by a combination of molecular, genetic and cytogenetic experiments (fluorescence in situ hybridization to spread pollen mother cells at meiotic prophase I). Our data clearly demonstrate that Agrobacterium-mediated transfer of a targeting T-DNA with a single lox site allows the isolation of multiple chromosomal rearrangements, including translocation and deletion events. Given that the complete sequence of the Arabidopsis genome will have been determined shortly this method has significant potential for applications in functional genomics.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Physics of the solid state 42 (2000), S. 734-738 
    ISSN: 1063-7834
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract An experimental study is reported of the nonlinear magnetoelectric effect in the metastable orthor-hombic ferroelectric ferroelastic paramagnetic β′ phase of Gd2(MoO4)3 in magnetic fields of up to 20 T and at temperatures of 4.2 and 0.4 K. It is shown that the present models of the paramagnetoelectric effect can be reconciled with experiments only for low magnetic fields. A new approach to the description of the magnetoelectric effect in rare-earth molybdates is proposed, which is based on a model of single-ion magnetostriction.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Journal of experimental and theoretical physics 90 (2000), S. 1042-1049 
    ISSN: 1090-6509
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We investigated the in-plane magnetoresistance and the Hall effect of high-quality Bi2Sr2CuOx single crystals with T c (midpoint) = 3.7–9.6 K in dc magnetic fields up to 23 T. For T 〈 10 K, the crystals show the classical positive magnetoresistance. Starting at T ≈ 14 K, an anomalous negative magnetoresistance appears at low magnetic fields; for T ≥ 40 K, the magnetoresistance is negative in the whole studied range of magnetic fields. Temperature and magnetic field dependences of the negative-magnetoresistance single crystals are qualitatively consistent with the electron interaction theory developed for simple semiconductors and disordered metals. As is observed in other cuprate superconductors, the Hall resistivity is negative in the mixed state and changes its sign with increasing field. The linear T-dependence of cotθH for the Hall angle in the normal state closely resembles that of the normal-state resistivity as expected for a Fermi liquid picture.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 112 (2000), S. 6949-6952 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: It is investigated to which extent the effect of intramolecular electron correlation on intermolecular first-order Coulomb and exchange energies can be accounted for when solely the reference determinant of the Brueckner coupled-cluster-doubles scheme is used to construct the charge density and the density matrices of the monomers. Considering the dimers He2, Ne2, Ar2, NeAr, NeHF, ArHF, (H2)2, (HF)2, and (H2O)2 the Brueckner orbital approximation in general is found to improve considerably upon the results of the Hartree–Fock determinant. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 116 (2002), S. 3277-3285 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: A model of the polarizability of carbon disulfide dimers was constructed, using polarizabilities from accurate time-dependent density functional theory calculations as reference. This direct reaction field model takes dipole-induced dipole effects, induced multipole effects and effects due to the overlap of the electronic clouds into account in an approximate way. The importance of the induced multipole and the overlap effects is investigated. This polarizability model is subsequently used to calculate the third-order time-domain Raman response of liquid carbon disulfide. These results are compared to experimental data and earlier calculated response in which only dipole-induced dipole effects on the polarizability were included. The multipole effects are found to give a significant contribution to the subpico second part of the third-order Raman response. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 115 (2001), S. 5445-5453 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The vibrational frequencies of OH and NH groups which form hydrogen bonds to a water molecule are calculated using the complete active space self-consistent field (CASSCF) method and the second order perturbation theory based on the CASSCF reference (CASPT2). As model systems indole(H2O), phenol(H2O), and their corresponding cations are chosen. Furthermore, different isomers of the 3-aminophenol(H2O)+ and 4-aminophenol(H2O)+ clusters are considered. For all these clusters IR spectra are known, but the IR spectra of the ionic clusters in the region of the hydrogen-bonded OH and NH groups have not yet been well interpreted. Due to the strong anharmonicity of the OH and NH vibrations it is not possible to predict their frequencies by a simple scaling of harmonic values. By using different active spaces including both π-orbitals as well as σ-orbitals it is shown that the vibrational frequencies can be derived from potentials obtained from CASSCF single-point calculations along the OH and NH stretching modes. These vibrations can be regarded as proton-transfer coordinates. The calculated vibrational frequencies are in excellent agreement with the experimental values obtained for the investigated clusters. Furthermore, a strong shift of the OH stretching frequency is predicted by going from phenol(H2O)+ to aminophenol(H2O)+ clusters, explaining the completely different IR spectra of the investigated species. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
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