WorldWideScience
1

Multi-wavelength observations of the young binary system Haro 6-10: The case of misaligned discs  

CERN Document Server

Context. We present a multi-wavelength, high-resolution observational survey of the young binary system Haro 6-10 (GV Tau, IRAS 04263+2426), which is harbouring one of the few known infrared companions. Aims. The primary goal of this project is to determine the physical and geometrical properties of the circumstellar and circumbinary material in the Haro 6-10 system. Methods. High-resolution optical (HST/WFPC2) and near-infrared (VLT/NACO) images in different bands were analysed to investigate the large-scale structures of the material around the binary.Mid-infrared interferometry (VLTI/MIDI) and spectroscopy (TIMMI2 at the 3.6m ESO telescope) were carried out to determine the structure and optical depth of the circumstellar material around the individual components. Results. The multi-wavelength observations suggest that both components of the binary system Haro 6-10 are embedded in a common envelope. The measured ...

2011-01-01

2

Chemistry of dense clumps near moving Herbig-Haro objects  

British Library Electronic Table of Contents (United Kingdom)

Abstract Localized regions of enhanced emission from HCO+, NH3 and other species near Herbig-Haro objects (HHOs) have been interpreted as arising in a photochemistry stimulated by the HHO radiation on high-density quiescent clumps in molecular clouds. Static models of this process have been successful in accounting for the variety of molecular species arising ahead of the jet; however, recent observations show that the enhanced molecular emission is widespread along the jet as well as ahead. Hence, a realistic model must take into account the movement of the radiation field past the clump. It was previously unclear as to whether the short interaction time between the clump and the HHO in a moving source model would allow molecules such as HCO+ to reach high enough levels, and to survive fo...

2011-01-01

3

Nuclear moments and changes in rms-radii of neutron-deficient silver isotopes  

International Nuclear Information System (INIS)

... nuclear electric moments nuclear magnetic moments nuclear radii quadrupole

1987-03-23

5

Mean magnetic moments of polycrystalline Ce compounds in a tetragonal crystal field  

International Nuclear Information System (INIS)

An alternative and graphical representation of the magnetic moment and the effective paramagnetic moment for polycrystalline Ce compounds with tetragonal site symmetry is described. The reduced moments can be calculated by means of standard perturbation theory. The calculated values deduced from the ground states of CeCu_2Si_2, CeRu_2Si_2, and CePd_2Si_2 polycrystals are compared with experimental magnetic moments.

6

Magnetic phase transition in UPd_2Si_2  

International Nuclear Information System (INIS)

... fields magnetic moments neel temperature neutron diffraction order-disorder

7

A correction to the governor model moment of inertia  

International Nuclear Information System (INIS)

(15 Aug 1973). Canada Prakash, VR Indian Inst. of Tech., Kanpur. Dept.

8

Local Electrostatic Moments and Periodic Boundary Conditition  

Energy Technology Data Exchange (ETDEWEB)

Electronic structure calculations frequently invoke periodic boundary conditions to solve for electrostatic potentials. For systems that are electronically charged, or contain dipole (or higher) moments, this artifice introduces spurious potentials due to the interactions between the system and multipole moments of its periodic images in aperiodic directions. I describe a method to properly handle the multipole moments of the electron density in electronic structure calculations using periodic boundary conditions. The density for which an electrostatic potential is to be evaluated is divided into two pieces. A local density is constructed that matches the desired moments of the full density, and its potential computed treating this density as isolated. With the density of this local moment countercharge removed from the full density, the remainder density lacks the troublesome ...

1998-12-04

9

An alternative explanation of the COBE data  

Energy Technology Data Exchange (ETDEWEB)

The COBE data on cosmic background radiation (CBR) isotropy and spectrum are generally considered to be explicable only in the context of the Big Bang theory and to be confirmation of that theory. However, this data can also be explained by an alternative, non-Big Bang model which hypothesizes an intergalactic radio-absorbing and scattering medium. Dense, force-free magnetic filaments generated by quasars, active galactic nuclei and Herbig-Haro objects can remain stable in the intergalactic medium for many Gy. They will be opaque to radiation with wavelengths longer than 100--400 microns, and essentially transparent to shorter wavelengths. They are thus capable of thermalizing and isotropizing the cosmic background radiation, and of accounting for the observed decrease of radio luminosity of galaxies within increasing distance from earth. A simple, inhomogeneous model of such an absorbing medium can reproduce both the isotropy and spectrum of the CBR within the ...

1994-12-31

10

Nuclear moments of the 11/2"- isomer in "1"8"7Ir  

International Nuclear Information System (INIS)

... excited states iridium 187 isomeric nuclei magnetic fields nuclear electric

11

Moment of inertia calculations for some even-even rare earth nuclei  

International Nuclear Information System (INIS)

... angular momentum cranking model even-even nuclei gadolinium 156 governor

12

Media Training  

ScienceCinema

...global warming issues ...people stopping we put a big issue with global warming copenhagen going on at the moment it's a waste of money ...

13

Inelastic and non-single-diffraction factorial moments from phenomenological models for elastic hadron scattering  

International Nuclear Information System (INIS)

We calculate the normalized factorial moments of multiplicity distributions through three models for elastic hadron scattering (Chou-Yang, Henzi-Valin and Menon-Pimentel). Connections between the moments and the inelastic overlap function and/or eikonal function are obtained by means of an impact parameter representation for the multiplicity distribution. The predictions are compared with experimental data on factorial moments from both inelastic and non-single-diffractive events. The model results present best agreement with the inelastic events and data favour the model by Henzi and Valin. (author)

14

Fe clusters on Ni and Cu: size and shape dependence of the spin moment  

Energy Technology Data Exchange (ETDEWEB)

We present ab-initio calculations of the electronic structure of small Fe clusters (1-9 atoms) on Ni(001), Ni(111), Cu(001) and Cu(111) surfaces. Our focus is on the spin moments and their dependence on cluster size and shape. We derive a simple quantitative rule that relates the moment of each Fe atom linearly to its coordination number. Thus, for an arbitrary Fe cluster the spin moment of the cluster and of the individual Fe atoms can be readily found if the positions of the atoms are known. (orig.)

2006-01-01

15

Evidence for asymmetric shapes from high-spin odd-A spectra  

International Nuclear Information System (INIS)

... coupling deformed nuclei gold 195 high spin states iridium 187 moment of

18

Spontaneous radiation-induced alignment of dipole moments of atoms moving in a medium  

International Nuclear Information System (INIS)

The effect on an oscillator moving in a medium produced by that part of the radiative force which does not perform work but creates and angular moment is considered. It is shown that the radiative torque turns the dipole toward the axis along which it is moving. Near the axis of motion the dipole executes small oscilltions. The frequency of the oscillations is determined. This effect leads to spontaneous alignment of the dipole moments on moving through the medium. The feasibility of observing the effect experimentally is discussed.

1986-01-01

19

Hidden Markov Mixture Autoregressive Models: Stability and Moments  

CERN Document Server

This paper introduces a new parsimonious structure for mixture of autoregressive models. the weighting coefficients are determined through latent random variables, following a hidden Markov model. We propose a dynamic programming algorithm for the application of forecasting. We also derive the limiting behavior of unconditional first moment of the process and an appropriate upper bound for the limiting value of the variance. This can be considered as long run behavior of the process. Finally we show convergence and stability of the second moment. Further, we illustrate the efficacy of the proposed model by simulation and forecasting.

2011-01-01

20

Asymmetric rotor model for decoupled bands in transitional odd-mass nuclei  

International Nuclear Information System (INIS)

The high-spin states in transitional odd-mass nuclei are studied in terms of an odd quasi-particle coupled to an asymmetric rotor with a variable moment of inertia (VMI). In order to take into account the VMI, the basis states are expanded in terms of the core eigenfunctions. Excitation energies, quadrupole moments, magnetic moments, B(E2) values and B(M1) values are calculated and compared with the experimental data for nuclei in Au and La regions. On comparison with other descriptions it is found that the treatment with VMI provides a more satisfactory explanation of the data. (Auth.).

21

Paramagnetic properties of the RCo_2 compounds (R = rare earth)  

International Nuclear Information System (INIS)

The paramagnetic susceptibilities of all the RCo_2 compounds for which measurements are available are found to obey a Curie-Weiss law consistent with the modified indirect exchange model. The rare-earth ions are in a well defined tripositive valence state. Paramagnetic moments and paramagnetic Curie temperatures are obtained for these materials for the first time. The paramagnetic moments of these materials are changed from their free-ion values by the effects of itinerant electron polarisation, an effect which is particularly large for SmCo_2 whose paramagnetic moment is almost three times greater than the free-ion value. The modified indirect exchange model is found to be able to give a full description of the magnitude of the rare-earth, cobalt and diffuse moments in polarised neutron experiments. The band structures of the light RCo_2 compounds are found to be distinctly different to those of the ...

1984-03-01

22

Modeling and numerical simulation of linear and nonlinear spacecraft attitude dynamics and gravity gradient moments: A comparative study  

British Library Electronic Table of Contents (United Kingdom)

In this paper linear and nonlinear models of spacecraft attitude dynamics equations and gravity gradient moments are investigated. In addition, effects of gravity gradient moments on attitude dynamics of the satellite are studied. The purpose of this paper is to present a comparison between nonlinear and linear models of spacecraft attitude dynamics and gravity gradient moments in order to determine divergence of linear approximation from the nonlinear model. Simulation results indicate that designer of spacecraft attitude control subsystem should be meticulous in applying linear approximation of equations especially in low earth orbits. Consequently, finding an upper bound for small angle to keep the linear model valid and precise enough would be a vital part of using linear approximation...

2012-01-01

23

Magnetic Moments and Electromagnetic Radii of Nucleon and ?(1232) in an Extended Goldstone-Boson-Exchange Model  

International Nuclear Information System (INIS)

We derive the exchange currents of pseudoscalar, vector, and scalar mesons from Feynman diagrams, and use them to calculate the magnetic form factors of nucleon and ?(1232). The magnetic moments and electromagnetic radii are obtained by using those form factors and the parameters determined from the masses of nucleon and ?(1232). We find the magnetic moments and electromagnetic radii of nucleon and ?(1232) can be produced very well in the extended Goldstone-Boson-exchange model in which all of pseudoscalar, vector, and scalar meson nonet are included. The magnetic moments of ?(1232) are closer to experiment values and results from lattice calculation than the results obtained by the model without other mesons except for pion and sigma.

2005-01-15

26
27

Aerodynamic Static Differential Pressure  

Science.gov (United States)

aerodynamic force and moment values. Only the solid and the 25 percent porous dishes were tested for the static pressure values used primarily to determine ...

28

APERTURE SYNTHESIS IMAGING OF V892 Tau AND PV Cep: DISK EVOLUTION  

International Nuclear Information System (INIS)

I present a study of two Herbig Ae stars that are in completely different evolutionary stages: V892 Tau and PV Cep. Using sub-arcsecond interferometric observations obtained with the Combined Array for Research in Millimeter-wave Astronomy at #lambda# = 1.3 and 2.7 mm, I have for the first time resolved their disks. I deduce that the 5 Myr old V892 Tau has a low dust opacity index #beta# = 1.1 and a disk mass of #approx#0.03 M_s_u_n. These values correspond to the growth of its dust into large, up to centimeters size, structures. In contrast, the very young (a few x10"5 yr) PV Cep has a quite high opacity index #beta# = 1.75 and a more massive disk 0.8 M_s_u_n. PV Cep has the youngest resolved disk around any Herbig Ae star. Unlike the youngest T Tauri and Class 0 stars, which contain large and processed grains, the young Herbig Ae star, PV Cep, disk contains interstellar-medium-like unprocessed dust. This suggests that PV Cep's dust evolution is slower than T Tauri stars'. I also ...

2010-10-10

29

Wind-Tunnel Measurements of Aerodynamic Forces and Moments on a Model of a Semi-Submersible Offshore Drilling Rig.  

Science.gov (United States)

The model was based on a SEDCO 700 series semi-submersible offshore drilling rig used for operations in the North Sea. This report supplements earlier work on wind-heeling moments which are required to establish stability criteria on semi-submersibles. Wi...

1982-01-01

30

Time Average Aerodynmic Forces and Moments on a National Model of a Semi-Submersible Offshore Rig. Part 1. Measurements. Part 2. Analysis of Results for the Basic Model.  

Science.gov (United States)

Wind-tunnel measurements were taken of the time-average aerodynamic forces and moments on a notional model of a semi-submersible offshore drilling rig at two heights and at various attitudes to the wind. Attempts were made to analyze the separate effects ...

1982-01-01

31

Spin polarization and structure of the sup(181, 182, 187)Re and "1"7"7Ta states  

International Nuclear Information System (INIS)

The properties of "1"7"7Ta and sup(181, 182, 187)Re states are discussed in the framework of the rotational model with the Coriolis coupling. The relations are obtained for calculating magnetic moments by this model in the jlK representation. The valent-nucleon spin polarization found on the basis of a comparison of the experimental values of magnetic moments with the calculated ones, is shown to depend on the number of nucleons of the same type.

1978-03-01

32

Instability of 4f and 3d magnetic moments under high pressure  

International Nuclear Information System (INIS)

The purpose of this paper is to demonstrate how recent experimental results of "1"5"1Eu and "5"7Fe high pressure Moessbauer studies in 4f and 3d metallic magnetic systems can contribute to a deeper understanding of the nature of local moment (4f) and itinerant (3d) magnetism in these systems. Special emphasis is given on the comparison of the experimental results with related theoretical models. (orig.).

33

Indirect evidence for the existence of tachyons; a unified approach to the pion #-># muon #-># electron conversion problem  

International Nuclear Information System (INIS)

Using the experimentally determined cutoff energies of the muon-electron and the pion-electron conversion curves in a tachyon-bradyon model of the electron and the muon, the magnetic moments of these particles have been derived and found to be the Bohr magnetons identically. The tachyons, being bound to the bradyons and unable to drop below the speed of light, cause the bradyons to revolve in an orbit. It is this orbital motion of the charged bradyons that generates the magnetic moments.

34

Electromagnetic structure of decuplet baryons towards the chiral regime  

Science.gov (United States)

The electromagnetic properties of the baryon decuplet are calculated in quenched QCD on a 20{sup 3}x40 lattice with a lattice spacing of 0.128 fm using the fat-link irrelevant clover fermion action with quark masses providing a pion mass as low as 300 MeV. Magnetic moments and charge radii are extracted from the electric and magnetic form factors for each individual quark sector. From these, the corresponding baryon properties are constructed. We present results for the higher-order moments of the spin-3/2 baryons, including the electric-quadrupole moment E2 and the magnetic-octupole moment M3. The world's first determination of a nonzero M3 form factor for the {delta} baryon is presented. With these results we provide a conclusive analysis which shows that decuplet baryons are deformed. We compare the decuplet-baryon results from a similar lattice calculation of the octet baryons. We establish ...

2009-09-01

35

Determination of the /sup 242m/Am nuclear moments  

Energy Technology Data Exchange (ETDEWEB)

The hyperfine structure of Am atoms was investigated in an atomic beam by laser spectroscopy. The observed splittings were evaluated with respect to the magnetic dipole and electric quadrupole moments of /sup 242m/Am. The results are: ..mu../sub I/(/sup 242m/Am) = +0.97(5) nm, Q(/sup 242m/Am) = +6.5(2.0) b.

1988-07-01

36

Cerium moment collapse in ternary silicides CePd[sub 2[minus][ital x  

Energy Technology Data Exchange (ETDEWEB)

Cerium [ital L][sub 3] XANES (x-ray-absorption near-edge-structure) spectra were analyzed to separate Ce moment contributions and mixed valence (MV) in complex magnetic silicides CePd[sub 2[minus][ital x

1994-05-01

37

The high-density regime of kinetic-dominated loop quantum cosmology  

CERN Document Server

We study the dynamics of states perturbatively expanded about a harmonic system of loop quantum cosmology, exhibiting a bounce. In particular, the evolution equations for the first and second order moments of the system are analyzed. These moments back-react on the trajectories of the expectation values of the state and hence alter the energy density at the bounce. This analysis is performed for isotropic loop quantum cosmology coupled to a scalar field with a small but non-zero constant potential, hence in a regime in which the kinetic energy of matter dominates. Analytic restrictions on the existence of dynamical coherent states and the meaning of semi-classicality within these systems are discussed. A numerical investigation of the trajectories of states that remain semi-classical across the bounce demonstrates that, at least for such states, the bounce persists and that its properties are similar to the standard case, in which the ...

2010-01-01

38

Nuclear magnetic moment measurements through hyperfine interactions in highly stripped ions  

International Nuclear Information System (INIS)

Time-differential magnetic moment measurements on the first-excited Isup(#pi#)=2"+ states in "2"0Ne and "2"4Mg with mean lives of 1.0 and 2.1 ps, respectively are described. The lifetime of the latter state was determined simultaneously. A special detection geometry was designed to improve the experimental #gamma#-ray anisotropy measured with finite-size detectors. For "2"0Ne also a time-integral measurement with charge-state separation was performed. The necessary electronics circuitry built to perform these complicated measurements and the plunger assembly with laser interferometer are also described. A magnetic moment measurement of "2"2Ne(2_1"+) with tau=5.0 ps and transient field measurements at low and high recoil velocities are reported. A discussion of possible extensions of the techniques are given. (Auth.).

1975-09-15

39

Large Magnetic Moments of Arsenic-Doped Mn Clusters and their Relevance to Mn-Doped III-V Semiconductor Ferromagnetism  

CERN Document Server

We report electronic and magnetic structure of arsenic-doped manganese clusters from density-functional theory using generalized gradient approximation for the exchange-correlation energy. We find that arsenic stabilizes manganese clusters, though the ferromagnetic coupling between Mn atoms are found only in Mn$_2$As and Mn$_4$As clusters with magnetic moments 9 $\\mu_B$ and 17 $\\mu_B$, respectively. For all other sizes, $x=$ 3, 5-10, Mn$_x$As clusters show ferrimagnetic coupling. It is suggested that, if grown during the low temperature MBE, the giant magnetic moments due to ferromagnetic coupling in Mn$_2$As and Mn$_4$As clusters could play a role on the ferromagnetism and on the variation observed in the Curie temperature of Mn-doped III-V semiconductors.

2005-01-01

40

Constraining Parity Violation in Gravity with Measurements of Neutron-Star Moments of Inertia  

CERN Document Server

Neutron stars are sensitive laboratories for testing general relativity, especially when considering deviations where velocities are relativistic and gravitational fields are strong. One such deviation is described by dynamical, Chern-Simons modified gravity, where the Einstein-Hilbert action is modified through the addition of the gravitational parity-violating Pontryagin density coupled to a field. This four-dimensional effective theory arises naturally both in perturbative and non-perturbative string theory, loop quantum gravity, and generic effective field theory expansions. We calculate here Chern-Simons modifications to the properties and gravitational fields of slowly spinning neutron stars. We find that the Chern-Simons correction affects only the gravitomagnetic sector of the metric to leading order, thus introducing modifications to the moment of inertia but not to the mass-radius relation. We show that an observational determination of the ...

2009-01-01

41

Cerium moment collapse in ternary silicides CePd_2_-_xMn_xSi_2 (0#<=#x#<=#2)  

International Nuclear Information System (INIS)

Cerium L_3 XANES (x-ray-absorption near-edge-structure) spectra were analyzed to separate Ce moment contributions and mixed valence (MV) in complex magnetic silicides CePd_2_-_xMn_xSi_2 (0#<=#x#<=#2). The Ce valence mixing does not vary linearly with x, but increases rapidly for x#>=#1.5. The associated moment collapse correlates with pronounced deviations of the unit-cell volume from Vegard law and the onset of structural instability. Reorientation of [001] Mn 3d antiferromagnetic order for x<2 appears to rapidly suppress the weak Ce valence mixing coexisting with antiferromagnetic order in CeMn_2Si_2.

42

Antiferromagnetic ordering of defects in GaAs  

Energy Technology Data Exchange (ETDEWEB)

The magnetic susceptibility of GaAs samples containing a large concentration of native defects was investigated by dc magnetization measurements. Thin GaAs films grown by molecular-beam epitaxy at very low temperatures and bulk GaAs:S samples irradiated with fast neutrons have been studied. For all samples, the susceptibility follows a Curie-Weiss law, indicating the presence of localized magnetic moments. These moments are attributed to unpaired spins located at the native defects. Negative Curie-Weiss temperatures found for both neutron-irradiated and low-temperature-grown GaAs is a clear manifestation of an antiferromagnetic interaction between the moments. The presence of a highly inhomogeneous distribution of native defects has to be assumed to account for the observed antiferromagnetic ordering.

1992-10-15

43

Site Error There's a problem with ... - NASA Technical Reports Server  

Science.gov (United States)

Mar 1, 2011 ... Bending moments recorded by sensors on the aluminum tube. ... the escape rocket motor, tests also were made with the escape tower and rocket .... Incoming photographic data will be electronically converted and processed ...

44

Selected results in hadron structure from lattice QCD  

Energy Technology Data Exchange (ETDEWEB)

I present results for the mass spectrum of excited baryons and pentaquarks using overlap fermions and Bayesian curve-fitting method; and magnetic moments and polarizabilities for a variety of hadrons in the background field method.

2006-03-15

45

Selected results in hadron structure from lattice QCD  

International Nuclear Information System (INIS)

I present results for the mass spectrum of excited baryons and pentaquarks using overlap fermions and Bayesian curve-fitting method; and magnetic moments and polarizabilities for a variety of hadrons in the background field method.

2006-03-01

46

Neutrino emission in neutron matter from magnetic moment interactions  

CERN Document Server

Neutrino emission drives neutron star cooling for the first several hundreds of years after its birth. Given the low energy ($\\sim$ keV) nature of this process, one expects very few nonstandard particle physics contributions which could affect this rate. Requiring that any new physics contributions involve light degrees of freedom, one of the likely candidates which can affect the cooling process would be a nonzero magnetic moment for the neutrino. To illustrate, we compute the emission rate for neutrino pair bremsstrahlung in neutron-neutron scattering through photon-neutrino magnetic moment coupling. We also present analogous differential rates for neutrino scattering off nucleons and electrons that determine neutrino opacities in supernovae. Employing current upper bounds from collider experiments on the tau magnetic moment, we find that the neutrino emission rate can exceed the rate through neutral current electroweak ...

2004-01-01

47

Magnetization and 61Ni Moessbauer effect study of the ternary arsenide CrNiAs  

International Nuclear Information System (INIS)

The results of x-ray diffraction, dc magnetization, and 61Ni Moessbauer spectroscopy studies of the ternary arsenide CrNiAs are reported. This compound crystallizes in the orthorhombic Fe2P-type structure (space group P6-bar2m) with the lattice parameters a 6.1128(2) A and c = 3.6585(1) A. CrNiAs is a mean-field ferromagnet with Curie temperature TC = 171.9(1) K and the critical exponents ? 0.514(18), ? = 1.010(16), and ? = 2.922(10). The temperature dependence of the magnetic susceptibility above TC follows the modified Curie-Weiss law with a paramagnetic Curie temperature of 176.0(3) K and effective magnetic moment per transition metal atom of 2.42(1) ?B. The magnetic moment per formula unit at 4.2 K is found to be 1.114(33) ?B. The hyperfine magnetic field at 61Ni nuclei at 4.2 K of 41.5(1.0) kOe implies that the Ni atoms carry a magnetic moment of 0.15(3) ?B, and that the moment carried by the Cr ...

2008-08-13

48

Magnetic ordering in CeM_2Si_2 (M = Ag,Au,Pd,Rh) compounds as studied by neutron diffraction  

International Nuclear Information System (INIS)

We report the results of neutron-diffraction experiments on CeM_2Si_2 (M = Ag,Au,Pd,Rh) which were performed to explore the role of valence fluctuations and 4f hybridization in the magnetic ordering of cerium compounds. All four order antiferromagnetically, the first three exhibiting structures consisting of ferromagnetic layers with moments perpendicular to the layers, which are believed to be characteristic of 4f-4f interactions mediated through hybridization with conduction electrons. CePd_2Si_2 has an anomalously small moment (0.62#mu#/sub B/) in the ordered state. CeAg_2Si_2 exhibits an incommensurate longitudinal, static magnetization wave with moment and propagation direction along the a axis. The fourth compound, CeRh_2Si_2, has the highest known transition temperature (39 K) reported for cerium ordering; it exhibits another second-order transition at 27 K to a complex commensurate structure with modulated ...

49

Magnetic ordering in CeM/sub 2/Si/sub 2/ (M = Ag,Au,Pd,Rh) compounds as studied by neutron diffraction  

Energy Technology Data Exchange (ETDEWEB)

We report the results of neutron-diffraction experiments on CeM/sub 2/Si/sub 2/ (M = Ag,Au,Pd,Rh) which were performed to explore the role of valence fluctuations and 4f hybridization in the magnetic ordering of cerium compounds. All four order antiferromagnetically, the first three exhibiting structures consisting of ferromagnetic layers with moments perpendicular to the layers, which are believed to be characteristic of 4f-4f interactions mediated through hybridization with conduction electrons. CePd/sub 2/Si/sub 2/ has an anomalously small moment (0.62..mu../sub B/) in the ordered state. CeAg/sub 2/Si/sub 2/ exhibits an incommensurate longitudinal, static magnetization wave with moment and propagation direction along the a axis. The fourth compound, CeRh/sub 2/Si/sub 2/, has the highest known transition temperature (39 K) reported for cerium ordering; it exhibits another second-order transition at 27 K to a complex ...

1984-03-01

50

Magnetic nanoparticle detection using nano-SQUID sensors  

International Nuclear Information System (INIS)

We demonstrate detection of a single core-shell magnetite-silica nanoparticle (outer diameter #approx#120 nm, moment #approx#10"4#mu#_B) using an Nb dc superconducting quantum interference device (SQUID) with the loop size of 350 nm operational at T < 10 K. The system noise was minimized down to 0.2 #mu##PHI#_0 Hz"-"1"/"2 using a cryogenic SQUID series array pre-amplifier. Initial measurements of an individual magnetic nanoparticle were performed and a clear change of the noise spectra of the nano-SQUID was detected at low frequencies in the presence of the nanoparticle. Similar behaviour was confirmed with an FePt nanoparticle with a larger magnetic moment (diameter #approx#150 nm, moment #approx#10"6#mu#_B). Thus, we demonstrate a magnetic sensor based on a dc nano-SQUID and enabling detection of small moments (potentially down to a few electron spins). Such a sensor is of considerable significance ...

2010-12-01

51

Magnetic fields of x-ray pulsars  

Energy Technology Data Exchange (ETDEWEB)

An analytic model of magnetic torques applied to an accreting neutron star is employed to evaluate the magnetic dipole moments of x-ray pulsars. A new type of close binary system containing a neutron star is suggested.

1982-09-01

54

Inside the LEP control room at start-up  

CERN Multimedia

Physicists grouped around a screen in the LEP control room at the strat-up of LEP on 14 July 1989. The emotion of the moment is clear. Carlo Rubbia, Director-General of CERN at the time, is in the centre and on his left, Herwig Schopper, former Director-General of the Organization.

1989-01-01

55

Feynmann variance-to-mean method  

Energy Technology Data Exchange (ETDEWEB)

The Feynmann and other fluctuation techniques have been shown to be useful for determining the multiplication of subcritical systems. The moments of the counting distribution from neutron detectors is analyzed to yield the multiplication value. We present the methodology and some selected applications and results and comparisons with Monte Carlo calculations.

1985-01-01

56

Exact moment of tendon of pectoralis major muscle rupture captured on video  

UK PubMed Central (United Kingdom)

A powerlifting athlete ruptured his left tendon of the pectoralis major muscle while attempting to lift 160 kg in a Brazilian bench press championship. The injury seemed to occur in the concentric...Full Text Available

2007-09-01

57

Emergent magnetic moments produced by self-damage in plutonium  

UK PubMed Central (United Kingdom)

Plutonium possesses the most complicated phase diagram in the periodic table, driven by the complexities of overlapping 5f electron orbitals. Despite the importance of the 5f...Full Text Available

2006-11-14

58

ESTIMATION OF WATER QUALITY CRITERIA VIOLATION FREQUENCIES USING PEARSON PERCENTILES  

Science.gov (United States)

A numerical technique is developed for estimating water quality violation frequencies due to pollutant discharges from urban areas during combined sewer overflow events. The first four moments of in-stream pollutant concentration are found by integrating a pollutant loading - wat...

59

Clinical Correlates to Laboratory Measures for use in Non-Contact Anterior Cruciate Ligament Injury Risk Prediction Algorithm  

UK PubMed Central (United Kingdom)

BackgroundProspective measures of high knee abduction moment during landing identify female athletes at high risk for non-contact anterior cruciate ligament injury....Full Text Available

2010-08-01

60

Behavior of instrumented model batter piles in clay  

Energy Technology Data Exchange (ETDEWEB)

Pile foundations in several coastal and offshore structures are subjected to significant amounts of lateral loads due to wave action. Usually batter piles are adopted to resist large lateral loads. In this investigation an attempt has been made to study the behavior of batter pile in clayey soils through an experimental program carried out on instrumented model aluminium piles of 26 mm diameter in a test tank of size, 1,200 mm x 800mm x 1,100 mm. The pile was instrumented with electrical resistance type strain gauges to determine the bending moment variations along the depth of embedment of pile. Bending moment vis depth relationships were used to determine the Soil reaction (p) and lateral displacement (y) along the length of the pile for the applied load. From the bending moment vs depth curves it is found that depth of maximum bending moment is greater for negative batter pile than for vertical and ...

1995-12-31

61

[The study of the mixing layer by the point image method].  

Science.gov (United States)

The properties of the mixing layer in dynamic systems were studied by the example of a mathematical model of the cubic image type. Its role in the generation of information and the evolution of its significance was shown. At the moment of generation, information is of zero significance, and this significance then increases. A criterion of efficiency was proposed, and the optimum moment of making a decision in creative work was determined. It was shown that the increase in the variability of the parameters of a living system upon entry into the mixing layer and its decrease upon exit can serve as objective indicators of the transition of the system from one dynamic regime (attractor) to another. PMID:12723364

62

Three pitch control systems for vertical axis wind turbines compared  

Energy Technology Data Exchange (ETDEWEB)

The desirable performance attributes of a vertical axis wind turbine (VAWT) include high starting torque, high peak efficiency, broad operating range and a reasonable insensitivity to the parameters that define its operation. The theoretical performance of three variable pitch mechanisms for VAWT are compared. Cycloturbines use cam devices or gears to impose a sinusoidal pitch regime. In the mass-stabilised system, pitch is determined by the interplay of two opposing moments on the blades. These two mechanisms are compared with Aeropitch, a hypothetical pitch control system in which stabilising moments are related to the blade relative velocity. (Author)

1992-01-01

63

Reflections on a future international convention on safety in radioactive waste management - September 1994  

Energy Technology Data Exchange (ETDEWEB)

This probably is a suitable moment for work to begin on an international Convention in this area, although it is a difficult task. Generally speaking, the RADWASS (Radioactive Waste Safety Standards) Programme has achieved sufficient consensus, and might serve as an important basis for work in relation to the Convention. The Convention should not go into highly technical details since consensus at this level is more difficult at the present moment, although this will undoubtedly be achieved in the medium term. An important element of the Convention should be the regulation of movements of radioactive wastes at international level. (orig./HP)

1995-12-31

64

Nuclear magnetic resonance on oriented XVTa and XXTa  

Energy Technology Data Exchange (ETDEWEB)

XVTa and XXTa nuclei were oriented at low temperature as dilute impurities in Fe. The magnetic hyperfine splitting frequencies = B sub(HF)/Ih of the XVTa and XXTa ground states have been measured to be 320.45(11) and 317.552(55) MHz by using the technique of NMR-ON. Taking the known hyperfine field of Y Ta in Fe, the magnetic moments have been deduced: ( XVTa, 7/2 ) =2.270(45) and ( XXTa, 7/2 ) =2.250(45) sub(N). These values of the magnetic moments are discussed in the framework of the rotational model.

1984-08-01

65

Nuclear magnetic moments of "1"7"5Ta and "1"7"7Ta  

International Nuclear Information System (INIS)

"1"7"5Ta and "1"7"7Ta nuclei as dilute impurities in Fe were oriented at low temperatures. Using the technique of NMR/ON the magnetic moments have been measured: "+#mu#("1"7"5Ta, 7/2"+,"+=2.270(45) #mu# sub(N) and "+#mu#("1"7"5Ta, 7/2"+)"+=2.250(45) #mu# sub(N). These values are discussed in the framework of the rotational model. (author).

66

Neutron transition multipole moment for /sup 88/Sr(#alpha#,#alpha#')/sup 88/Sr (2"+, 1.84 MeV)  

International Nuclear Information System (INIS)

The neutron transition multipole moment, M/sub n/, for (0"+#->#2"+, 1.84 MeV) transition is inferred by measuring the (#alpha#,#alpha#') angular distribution at E/sub #alpha#/ = 50 MeV and comparing it with a microscopic distorted-wave Born approximation calculation. Proton transition densities are taken from electron scattering data. M/sub n//M/sub p/ is found to be substantially less than N/Z in agreement with the (p,p') result.

67

Moment based estimation of stochastic Kronecker graph parameters  

CERN Document Server

Stochastic Kronecker graphs supply a parsimonious model for large sparse real world graphs. They can specify the distribution of a large random graph using only three or four parameters. Those parameters have however proved difficult to choose in specific applications. This article looks at method of moments estimators that are computationally much simpler than maximum likelihood. The estimators are fast and in our examples, they typically yield Kronecker parameters with expected feature counts closer to a given graph than we get from KronFit. The improvement was especially prominent for the number of triangles in the graph.

2011-01-01

68

Microeconomics of the ideal gas like market models  

CERN Document Server

We develop a framework based on microeconomic theory from which the ideal gas like market models can be addressed. A kinetic exchange model based on that framework is proposed and its distributional features have been studied by considering its moments. Next, we derive the moments of the CC model (Eur. Phys. J. B 17 (2000) 167) as well. Some precise solutions are obtained which conform with the solutions obtained earlier. Finally, an output market is introduced with global price determination in the model with some necessary modifications.

2009-01-01

69

Magnetic structure of Ce(Ru_0_._9_6Pd_0_._0_4)_2Si_2  

International Nuclear Information System (INIS)

The magnetic structure of a tetragonal Ce(Ru_0_._9_6Pd_0_._0_4)_2Si_2 single crystal, determined by neutron diffraction measurements, is similar to that observed in Rh doped alloys. The magnetic moments are oriented and modulated along the c-axis. Here the wave vector is incommensurate: k=(0,0,0.38). At 1.5 K, the moment is estimated to about 0.3 #mu#_B. Magnetization, magnetoresistance and Hall effect measurements performed on this alloy are also reported. (orig.).

70

Magnetic properties of some RPd_2Si_2 compounds (R = Gd, Tb, Dy, Ho and Er)  

International Nuclear Information System (INIS)

The magnetic susceptibility of the ternary compounds, RPd_2Si_2 (where R=Gd, Tb, Dy, Ho and Er) has been measured. GdPd_2Si_2 and TbPd_2Si_2 order antiferromagnetically at 13 and 20 K respectively; the rest of the compounds do not show clear ordering down to 4.2 K. Palladium carries no moment in these compounds. The De Gennes formula is not obeyed indicating that the exchange interaction between the 4f moments via conduction electrons is not isotropic. (orig.).

71

Implantation of single-impurity Fe and its magnetic coupling in Er studied by TDPAD  

Energy Technology Data Exchange (ETDEWEB)

Single Fe impurities were implanted in an Er single crystal and found to occupy both substitutional and interstitial sites, below a temperature of 200 K. The local susceptibility of Fe on both sites follows a Curie-Weiss law and exhibits a positive local Curie constant, indicating an antiferromagnetic coupling between the Fe and the surrounding Er moments. The corresponding nuclear spin relaxation rates follow a Korringa law as a function of temperature, confirming the dominance of local magnetism and the formation of local moments on each of the sites occupied by Fe.

2004-05-01

72

A wrench for screwing and unscrewing lock connections  

Energy Technology Data Exchange (ETDEWEB)

A wrench is proposed for screwing and unscrewing lock connections, which includes a spring loaded base, a faceplate with low moment and high moment mechanisms and subassemblies for moving them. In order to increase the operational reliability, the wrench is equipped with uprights evenly disposed along the perimeter of the base with hinged suspensions for linking the base, the hinged suspension is made in the form of interconnected links for the upper and lower traverses with the hinges. One of the hinges is positioned between the upper traverse and the upright, while the other is located between the lower traverse and the base.

1983-01-01

73

NMR studies of the partially disordered state in a triangular antiferromagnet UNi_4B  

International Nuclear Information System (INIS)

A triangular antiferromagnet UNi_4B experiences a partially disordered state, in which two-thirds of U 5f moments order in a vertex-like structure and one-third of U 5f moments remain paramagnetic. Magnetization and NMR measurements of UNi_4B have been performed to study the dynamical properties of U magnetic moments in the partially disordered state. The value of the effective moment above T_N derived from the fitting of the Curie-Weiss law suggests a significant crystal field splitting and the Kondo effect. The Weiss temperature was also estimated to be -28 K, which suggests that the exchange interaction is antiferromagnetic. Furthermore, the exchange interaction estimated from the relaxation rate T_1"-"1 above 50 K is 18 K, which is close to the Weiss temperature. These results suggest that the dominant interactions between U moments are antiferromagnetic in the basal plane. The ...

2007-04-11

74

Perpendicular magnetic anisotropy of ultrathin FeCo alloy films on Pd(0 0 1) surface: First principles study  

International Nuclear Information System (INIS)

Using the full potential linearized augmented plane wave (FLAPW) method, thickness dependent magnetic anisotropy of ultrathin FeCo alloy films in the range of 1 monolayer (ML) to 5 ML coverage on Pd(0 0 1) surface has been explored. We have found that the FeCo alloy films have close to half metallic state and well-known surface enhancement in thin film magnetism is observed in Fe atom, whereas the Co has rather stable magnetic moment. However, the largest magnetic moment in Fe and Co is found at 1 ML thickness. Interestingly, it has been observed that the interface magnetic moments of Fe and Co are almost the same as those of surface elements. The similar trend exists in orbital magnetic moment. This indicates that the strong hybridization between interface FeCo alloy and Pd gives rise to the large magnetic moment. Theoretically calculated magnetic anisotropy shows that the 1 ML ...

2009-06-01

75

Manipulation of spin reorientation transition by Au capping in body-centered cubic Ni(001) film  

International Nuclear Information System (INIS)

The thickness dependent magnetic properties of artificially prepared ultrathin body-centered cubic Ni films have been explored using the all electron full potential linearized augmented plane wave (FLAPW) method. We have considered two types of BCC Ni(001) films: (i) pure BCC Ni(001) and (ii) Au capped BCC Ni(001) in the range from 1 monolayer (ML) to 4 ML of Au capping coverage. The average magnetic moment of pure BCC Ni(001) is about 0.63 #mu#_B and a typical surface enhancement is found with a magnetic moment of 0.78 #mu#_B. In the presence of an Au capping layer, the magnetic moment of interface Ni is strongly suppressed to approximately 0.5 #mu#_B and this causes a reduction of average magnetic moment. Nevertheless, the Au adlayer has no meaningful induced magnetic moment. The BCC pure Ni(001) films always have in-plane magnetization up to 11 ML, but very interestingly the ...

2008-12-03

76

Large orbital magnetic moment and its quenching in the itinerant uranium intermetallic compounds UTGa_5 (T=Ni, Pd, Pt)  

International Nuclear Information System (INIS)

The crystal structure, lattice strain due to the antiferromagnetic ordering, and magnetic form factor in the itinerant 5f compounds UTGa_5 (T=Ni, Pd, Pt) have been studied by neutron scattering. High-resolution powder diffraction revealed that the tetragonality of the U-Ga layers increases down to the series of the transition metal element T. The integrated intensities of the antiferromagnetic reflections can be well explained with the Neel-type structure for UNiGa_5, whereas UPtGa_5 has the antiferromagnetic stacking of the ferromagnetically ordered uranium moments in the c plane. In both compounds the uranium moments orient along the c axis with moments of 0.75(5) and 0.32(5) #mu#_B for UNiGa_5 and UPtGa_5, respectively. No magnetic peak could be observed in the powder diffraction pattern of UPdGa_5 due to the small magnetic moment less than the experimental sensitivity. The orbital contributions in ...

2003-12-01

77

Transport of sorbing solutes in randomly heterogeneous formations: Spatial moments, macrodispersion, and parameter uncertainty  

Energy Technology Data Exchange (ETDEWEB)

Expressions for the spatial moments and macrodispersion tensor for sorbing solutes in heterogeneous formations were presented using a probabilistic model of a fluid residence time coupled with the particle position analysis. The fluid residence time was defined as a fraction of the actual time during which the particle stayed in the mobile fluid phase of the aquifer. The fluid residence time is a random variable whose variability comes as a result of the non-equilibrium sorption properties. The sorbing solute was assumed to be governed with first-order linear kinetics. The closed-form expressions were based on the stationarity in the kinetic process and on the first-order approximation in the hydraulic conductivity field and in the fluid residence time. The non-equilibrium effects were presented as a function of the spatial variability in hydraulic conductivity and temporal variability in the fluid residence time. The importance of the non-equilibrium processes in ...

1993-06-01

78

Neutron diffraction and magnetization studies of pseudoternary HoRh_2_-_xPd_xSi_2 solid solutions (0#<=#x<2)  

International Nuclear Information System (INIS)

Neutron powder diffraction and magnetometric studies of the HoRh_2_-_xPd_xSi_2 series of solid solutions (x=0, 0.5, 0.75, 1.0, 1.5, 1.8) are reported. The intermetallics investigated crystallize in the body-centred-tetragonal ThCr_2Si_2-type structure (space group I4/mmm). All the samples order antiferromagnetically at low temperatures. For low values of the dilution parameter x a simple collinear antiferromagnetic structure of the AFI type is stable. Below T_N the magnetic moments are parallel to the c-axis and then, below T_t, deflect forming an angle #psi# with the c-axis. Further replacement of Rh by Pd results in the development of a sine-wave-modulated magnetic structure with one two-component propagation vector and magnetic moments in the basal plane. For x=1.8 a sine-wave-modulated structure similar to that reported for HoPd_2Si_2 (i.e. with a two-component propagation vector and magnetic moments parallel to the ...

2002-06-03

79

Magnetic moments of C isotopes studied with antisymmetrized molecular dynamics  

International Nuclear Information System (INIS)

We studied the magnetic dipole moments #mu# of even-odd C isotopes, ranging from proton-rich to neutron-rich nuclei, with antisymmetrized molecular dynamics (AMD). The results are in good agreement with the experimental data. In the "9C ground state the total intrinsic spin of the protons is found to be nonzero (S_p#not =#0), which is unusual in even-odd nuclei. The interesting point is that the spin-orbit force breaks slightly the coupling off of intrinsic spins of the even nucleon group in isospin T=3/2 nuclei. This result is consistent with the newly measured #mu# data that, when combined with "9Li data, indicate an unusual left-angle #sigma# right-angle value larger than unity. A #mu# moment -1.05#mu#_N of "1"7C is theoretically predicted. We also show a good reproduction of E2 transition data. copyright 1996 The American Physical Society.

80

Magnetic moment measurements of gadolinium, holmium and ytterbium tartrate trihydrate crystals  

British Library Electronic Table of Contents (United Kingdom)

Magnetic moment and susceptibility of single crystals of rare earth tartrates of the type R(C4H4O6)(C4H5O6)3H2O (where R = Gd, Ho, and Yb), using a vibration sample magnetometer are reported. The experimental values of molar susceptibilities for Gd(C4H4O6)(C4H5O6)3H2O, Ho(C4H4O6)(C4H5O6)3H2O, and Yb(C4H4O6)(C4H5O6)3H2O are 2.58x10-2, 4.66x10-2, and 8.03x10-3 (in cgs em units), respectively. The calculated effective magnetic moments are in good agreement with the theoretical predictions on rare earth ions.

2008-01-01

81

Anomalous tensor magnetic moments and form factors of the proton in the self-consistent chiral quark-soliton model  

Science.gov (United States)

We investigate the form factors of the chiral-odd nucleon matrix element of the tensor current. In particular, we aim at the anomalous tensor magnetic form factors of the nucleon within the framework of the SU(3) and SU(2) chiral quark-soliton model. We consider 1/N{sub c} rotational corrections and linear effects of SU(3) symmetry breaking with the symmetry-conserving quantization employed. We first obtain the results of the anomalous tensor magnetic moments for the up and down quarks: {kappa}{sub T}{sup u}=3.56 and {kappa}{sub T}{sup d}=1.83, respectively. The strange anomalous tensor magnetic moment is yielded to be {kappa}{sub T}{sup s}=0.2{approx}-0.2, that is compatible with zero. We also calculate the corresponding form factors {kappa}{sub T}{sup q}(Q{sup 2}) up to a momentum transfer Q{sup 2{<=}}1 GeV{sup 2} at a renormalization scale of 0.36 GeV{sup 2}.

2010-09-01

82

Program NetMoment; Simultaneous Calculation of Moment, Source Corner Frequency, and Site Specific t* from Network Recordings  

Energy Technology Data Exchange (ETDEWEB)

The purpose of computer program NetMoment (Appendix I) is to utilize fundamental knowledge of earthquake sources, propagation attenuation, and site response in a simultaneous inversion of network data to determine the moment and source corner frequency of earthquakes, and site specific t*. The source parameters are especially difficult to determine for small earthquakes. A fundamental problem in determining the source corner frequencies of small earthquakes is that site response can result in spectral corner frequencies in the range that may be expected from the earthquakes themselves. Several authors have identified this as fmax (Hanks, 1982), a constant corner frequency for small events so that below threshold moment (about 1.0 x 10{sup 21} dyne-cm) the corner frequency remains constant the size of events diminishes. Hutchings and Wu (1990) found that for the southern California region, events with ...

2001-12-12

83

X-ray magnetic form factor of UTe  

Energy Technology Data Exchange (ETDEWEB)

A measurement of the magnetic form factor of a ferromagnetic actinide compound of UTe with circularly polarized X-rays is reported. The present geometrical configuration of the measurement gives a form factor of L(k)+0.3S(k), where L(k) and S(k) are the form factors of the orbital and the spin magnetic moment, respectively. We have combined the X-ray magnetic form factor with the neutron one which gives L(k)+2S(k) (G. Busch et al.: J. Phys. C 12 (1979) 1391), and have deduced L(k) and S(k) separately. The obtained profiles of L(k) and S(k) show that the orbital and the spin magnetic moments are spatially spread out more than those calculated for a free uranium ion. (author).

1995-07-01

84

X-ray magnetic form factor of UTe  

International Nuclear Information System (INIS)

A measurement of the magnetic form factor of a ferromagnetic actinide compound of UTe with circularly polarized X-rays is reported. The present geometrical configuration of the measurement gives a form factor of L(k)+0.3S(k), where L(k) and S(k) are the form factors of the orbital and the spin magnetic moment, respectively. We have combined the X-ray magnetic form factor with the neutron one which gives L(k)+2S(k) (G. Busch et al.: J. Phys. C 12 (1979) 1391), and have deduced L(k) and S(k) separately. The obtained profiles of L(k) and S(k) show that the orbital and the spin magnetic moments are spatially spread out more than those calculated for a free uranium ion. (author).

85

What density-functional theory can tell us about the spin-density wave in  

International Nuclear Information System (INIS)

The energy-versus-volume curve of the spin-density wave (SDW) in body-centred-cubic Cr is calculated with the density functional theory/full-potential linearized augmented plane wave (DFT/FLAPW) method using the generalized gradient approximation (GGA). The predicted ground state is not the SDW, in contrast to an earlier FLAPW calculation. A conjecture is formulated that the widely varying results of the local density approximation (LDA) and GGA - and of different solution methods - can be scaled by the size of the calculated moment. As a consequence, experimentally relevant properties of the SDW can be calculated by tuning the moment. The implications of these results for the ability of DFT to describe Cr are discussed. (author)

2002-04-01

86

Seismic tests of post-tensioned self-centering building frames with column and slab restraints  

British Library Electronic Table of Contents (United Kingdom)

Post-tensioned (PT) self-centering moment frames have been developed as an alternative to typical moment-resisting frames (MRFs) for earthquake resistance. When a PT frame deforms laterally, gaps between the beams and columns open. However, the gaps are constrained by the columns and the slab in a real PT self-centering building frame. This paper presents a methodology for evaluating the column restraint and beam compression force based on the column deformation and gap openings at all stories. The method is verified by cyclic tests of a full-scale, two-bay by one-story PT frame. Moreover, a sliding slab is proposed to minimize restraints on the expansion of the PT frame. Shaking table tests were conducted on a reduced-scale, two-by-two bay one-story specimen, which comprises one PT frame ...

2011-01-01

87

Precipitation of ions induced by nonadiabatic motion in the outer cusp region  

Science.gov (United States)

The transport of magnetospheric particles in the outer cusp region is examined by means of three-dimensional single particle codes. It is shown that, at high altitudes, particles can experience nonadiabatic motions leading to significant magnetic moment changes. It is demonstrated that this nonadiabatic behavior can be interpreted, at least partly, by the action of an impulsive centrifugal force perturbing the particle gyromotion. Systematic trajectory calculations reveal that plasma sheet ions which ExB convert toward the magnetopause from low L-shells in the dayside sector are subjected to such nonadiabatic motions. As a result of magnetic moment damping, a number of them are injected into the loss cone and subsequently precipitate near the cusp equatorward edge.

88

Neutron transition multipole moment for /sup 88/Sr(. cap alpha. ,. cap alpha. ')/sup 88/Sr (2/sup +/, 1. 84 MeV)  

Energy Technology Data Exchange (ETDEWEB)

The neutron transition multipole moment, M/sub n/, for (0/sup +/..-->..2/sup +/, 1.84 MeV) transition is inferred by measuring the (..cap alpha..,..cap alpha..') angular distribution at E/sub ..cap alpha../ = 50 MeV and comparing it with a microscopic distorted-wave Born approximation calculation. Proton transition densities are taken from electron scattering data. M/sub n//M/sub p/ is found to be substantially less than N/Z in agreement with the (p,p') result.

1989-04-01

89

Magnetic properties of some RPd/sub 2/Si/sub 2/ compounds (R = Gd, Tb, Dy, Ho and Er)  

Energy Technology Data Exchange (ETDEWEB)

The magnetic susceptibility of the ternary compounds, RPd/sub 2/Si/sub 2/ (where R=Gd, Tb, Dy, Ho and Er) has been measured. GdPd/sub 2/Si/sub 2/ and TbPd/sub 2/Si/sub 2/ order antiferromagnetically at 13 and 20 K respectively; the rest of the compounds do not show clear ordering down to 4.2 K. Palladium carries no moment in these compounds. The De Gennes formula is not obeyed indicating that the exchange interaction between the 4f moments via conduction electrons is not isotropic.

1982-10-01

90

Magnetic properties of ErPd_2Si_2 from magnetization Moessbauer and neutron diffraction measurements  

International Nuclear Information System (INIS)

Magnetization, neutron diffraction and "1"6"6Er Moessbauer measurements on ErPd_2Si_2 are reported. Below 4.8 K ErPd_2Si_2 orders AF with complex modulated magnetic structures, where the Er moments are aligned along the c-axis. At 1.5 K a squared structure with #mu#_E_r #approx# 7.8(1)#mu#_B is found while a saturation Er moment of 8.2(2)#mu#_B is inferred from the hyperfine field data. The temperature dependence of the Moessbauer spectra in the paramagnetic region is explained in the framework of a relaxation model implying excited crystal field levels. Its analysis is used to estimate the B"m_n CEF parameters. (orig.).

91

Magnetic properties of Ab initio model of iron-based superconductors LaFeAsO  

International Nuclear Information System (INIS)

By using a variational Monte Carlo method, we examine an effective low-energy model for LaFeAsO derived from an ab initio downfolding scheme. We show that quantum and many-body fluctuations near the antiferromagnetic (AF) quantum critical point largely reduce the antiferromagnetic ordered moment. Our derived model not only quantitatively reproduces the small ordered moment in LaFeAsO, but also accounts for the diversity from LaFePO, BaFe_2As_2 to FeTe. Electron correlation is found to determine the observed material dependence. We also find that LaFeAsO is subject to large orbital fluctuations, sandwiched by the AF Mott insulator and weakly correlated metals. The orbital fluctuations and Dirac-cone dispersion hold keys for the diverse magnetic properties. (author)

2011-02-01

92

Magnetic order of Co{sub 0.1}Pt{sub 0.9} in proximity in CoPt{sub 3}  

Energy Technology Data Exchange (ETDEWEB)

A polarized neutron reflectometry study of the magnetization density depth profile of a Co{sub 0.1}Pt{sub 0.9}-CoPt{sub 3} bilayer film found evidence for an induced moment in the Co{sub 0.1}Pt{sup 0.9} overlayer in close proximity to the CoPt{sub 3} underlayer. If the moment of Co in these films is that of the bulk, then the {mu}{sub Pt} = 0.09(1){mu}{sub B} in the overlayer, and {mu}{sub Pt} = 0.04(1){mu}{sub B} in the underlayer. In addition, ferromagnetic order of the Co{sub 0.1}Pt{sub 0.9} overlayer was observed 8K above {Tc} for the material in the bulk.

1998-12-01

93

Magnetic and electronic properties of Mn{sub 4}Si{sub 7}  

Energy Technology Data Exchange (ETDEWEB)

We present a systematic study of the magnetization, Hall effect and specific heat on single crystals of Mn{sub 4}Si{sub 7}. Curie-Weiss law is observed above 43 K. At low-temperature moments order in an anisotropic helical state and are aligned above 1 T. We observe an anomalous Hall effect in both {rho}{sub H} vs. B and in R{sub H} vs. T curves and a field dependence of the low T specific heat due to spin fluctuations. The magnetic moments (p{sub eff} and p{sub sat}) are the lowest reported for similar itinerant magnetic systems, this suggests that Mn{sub 4}Si{sub 7} is a good candidate to observe critical quantum fluctuations expected for a marginal Fermi liquid.

2004-05-01

94

Local binary pattern based features for sign language recognition  

British Library Electronic Table of Contents (United Kingdom)

In this paper we focus on appearance features describing the manual component of Sign Language particularly the Local Binary Patterns. We compare the performance of these features with geometric moments describing the trajectory and shape of hands. Since the non-manual component is also very important for sign recognition we localize facial landmarks via Active Shape Model combined with Landmark detector that increases the robustness of model fitting. We test the recognition performance of individual features and their combinations on a database consisting of 11 signers and 23 signs with several repetitions. Local Binary Patterns outperform the geometric moments. When the features are combined we achieve a recognition rate up to 99.75% for signer dependent tests and 57.54% for signer indep...

2011-01-01

95

Linearization effect in multifractal analysis: Insights from Random Energy Model analysis  

CERN Document Server

The analysis of the linearization effect in multifractal analysis, and hence of the estimation of moments for multifractal processes, is revisited borrowing concepts from the statistical physics of disordered systems, notably from the analysis of the so-called Random Energy Model. Considering a standard multifractal process (compound Poisson motion), chosen as a simple representative example, we show: i) the existence of a critical order q* beyond which moments, though finite, cannot be estimated through empirical averages, irrespective of the sample size of the observation; ii) that multifractal exponents necessarily behave linearly in q, for q > q*. Tailoring the analysis conducted for the Random Energy Model to that of Compound Poisson motion, we provide explicative and quantitative predictions for the values of q* and for the slope controlling the linear behavior of the multifractal exponents. These quantities are shown to be related ...

2010-01-01

96

Generalised rotationally invariant core (RIC) model: a two mass-point approach  

International Nuclear Information System (INIS)

A generalised RIC model for the rotational - vibrational spectra of deformed even-even nuclei of ellipsoidal shape in the rare-earth region has been proposed by incorporating many important features of various microscopic models proposed earlier. The two mass-point model and the governor model moments of intertia are obtained on the basis of the proposed model with appropriate limiting values of the radius of the RIC. Also, the model moment of intertia goes to zero for spherical nuclei, thus giving no rotational spectra for such nuclei. A quantum mechanical treatment of the model on the basis of the two mass-point concept, is expected to give results which are in better agreement with experiments. (author).

97

Feeding of the megamouth shark (Pisces: Lamniformes: Megachasmidae) predicted by its hyoid arch: A biomechanical approach  

British Library Electronic Table of Contents (United Kingdom)

Abstract Studies of the megamouth shark, one of three planktivorous sharks, can provide information about their evolutionary history. Megamouth shark feeding has never been observed in life animals, but two alternative hypotheses on biomechanics suggest either feeding, i.e., ram feeding or suction feeding. In this study, the second moment of area of the ceratohyal cartilages, which is an indicator of the flexural stiffness of the cartilages, is calculated for 21 species of ram- and suction-feeding sharks using computed tomography. The results indicate that suction-feeding sharks have ceratohyal cartilages with a larger second moment of area than ram-feeding sharks. The result also indicates that the ram-suction index, which is an indicator of relative contribution of ram and suction behavi...

2011-01-01

98

Equivariant cohomology of K-contact manifolds  

CERN Document Server

We investigate the equivariant cohomology of the natural torus action on a K-contact manifold and its relation to the topology of the Reeb flow. Using the contact moment map, we show that the equivariant cohomology of this action is Cohen-Macaulay, which is a generalization of equivariant formality for torus actions without fixed points. As a consequence, a generic component of the contact moment map is a perfect Morse-Bott function for the basic cohomology of the orbit foliation F of the Reeb flow. Assuming that the closed Reeb orbits are isolated, we show that the basic cohomology of F is trivial in odd degrees, and its dimension equals the number of closed Reeb orbits. We characterize the K-contact manifolds with minimal number of closed Reeb orbits as real cohomology spheres. We also prove a GKM type theorem for K-contact manifolds, which allows us to calculate the equivariant cohomology algebra of K-contact manifolds in presence of the ...

2011-01-01

99

Effects of velocity-dependent force on the magnetic form factors of odd-Z  

International Nuclear Information System (INIS)

We investigate the effects of the velocity-dependent force on the magnetic form factors and magnetic moments of odd-Z nuclei. The form factors are calculated with the harmonic-oscillator wavefunctions. It is found that the contributions of the velocity-dependent force manifest themselves in the very large momentum transfer region (q?4 fm-1). In the low and medium q region the contributions of the velocity-dependent force are very small compared with those without this force. However, in the high-q region the contributions of the velocity-dependent force are larger than the normal form factors. The diffraction structures beyond the existing experimental data are found after the contributions of the velocity-dependent force are included. The formula of the correction to the single particle magnetic moment due to the velocity-dependent force is reproduced exactly in the long-wavelength limit (q=0) of the M1 form factor. (authors)

2008-03-01

100

Effects of confinement on the permanent electric-dipole moment of Xe atoms in liquid Xe  

CERN Document Server

Searches for permanent electric-dipole moments (EDM) of atoms provide important constraints on competing extensions to the standard model of elementary particles. Recently proposed experiment with liquid $^{129}$Xe [M.V. Romalis and M.P. Ledbetter, Phys. Rev. Lett. \\textbf{87}, 067601 (2001)] may significantly improve present limits on the EDMs. To interpret experimental data in terms of CP-violating sources, one must relate measured atomic EDM to various model interactions via electronic-structure calculations. Here we study density dependence of atomic EDMs. The analysis is carried out in the framework of the cell model of the liquid coupled with relativistic atomic-structure calculations. We find that compared to an isolated atom, the EDM of an atom of liquid Xe is suppressed by about 40%.

2004-01-01

101

Determination of critical length for pipe whip design  

Energy Technology Data Exchange (ETDEWEB)

Design of pipe whip restraints requires a knowledge of the maximum allowable unsupported pipe length. This paper presents a numerical method for calculating this critical length of the pipe. Salient features of the method are: (1) as a flow rounds an elbow, it exerts a transverse kick and an axial thrust to the pipe, both the axial thrust and the bending moment are considered; (2) the jet force is applied in an abrupt manner, the dynamic amplification factor (DAF) is determined from the load-deflection (H-{Delta}) curve of the pipe, by taking into consideration large strain, large deformation and the nonlinear stress-strain relationship of the piping material; (3) the ultimate capacity of the pipe under the combined action of an axial force and a bending moment is governed by an interaction formula. The maximum unsupported pipe length is calculated from this formula. Only the formulas and derivation are presented. Numerical results and design ...

1995-11-01

102

Coherent spontaneous radiation of Frenkel excitons  

International Nuclear Information System (INIS)

We have constructed a mathematical model that describes the coherent spontaneous radiation of a macroscopically filled exciton mode. We have demonstrated qualitatively ways in which a coherent subsystem of excitons can be formed. When this occurs under the influence of an external coherent source, exciton free induction occurs, while in the case of a spontaneous transition of the excitons to a coherent state through freezing of the reservoir of intermolecular interactions superradiance occurs. We have concluded that superradiance in the system of Frenkel excitons is possible under the influence of the non-Dicke mechanisms of self-induction of correlations, when the dipole transition moments of the individual atoms are coupled into a single macroscopic effective spin through their electrostatic interaction, this being analogous to the ordering of magnetic dipole moments in a ferromagnet.

1988-01-01

103

The Hannover thermal noise experiment  

International Nuclear Information System (INIS)

To analyse the thermal noise of the pendulum mode of a suspended mirror, we interferometrically detect the differential movement of two mirrors suspended as multiple-stage pendulums. We present the set-up of this experiment and the current sensitivity, and also the different steps that we took in the past to increase the sensitivity, which include an auto alignment of the laser beam into the resonator eigenmode, changes of the seismic isolation system to more damping stages and higher moments of inertia and an intensive noise hunting.

2004-03-07

104

Progress in lattice QCD  

Energy Technology Data Exchange (ETDEWEB)

After reviewing some of the mathematical foundations and numerical difficulties facing lattice QCD, I review the status of several calculations relevant to experimental high-energy physics. The topics considered are moments of structure functions, which may prove relevant to search for new phenomena at the LHC, and several aspects of flavor physics, which are relevant to understanding CP and flavor violation.

2002-09-30

105

Neutron multiplicities for the transplutonium nuclides  

Science.gov (United States)

This paper continues, with respect to the transplutonium nuclides, earlier efforts to collate and evaluate data from the scientific literature on the prompt neutron multiplicity distribution from fission and its first moment = ..sigma..nuPnu. The isotopes considered here for which P/sub nu/ and or data (or both) were found in the literature are of americium (Am), curium (Cm), berkelium (Bk), californium (Cf), einsteinium (Es), fermium (Fm), and nobelium (No).

1985-01-01

106

Neutron multiplicities for the transplutonium nuclides  

Energy Technology Data Exchange (ETDEWEB)

This paper continues, with respect to the transplutonium nuclides, earlier efforts to collate and evaluate data from the scientific literature on the prompt neutron multiplicity distribution from fission and its first moment = ..sigma..nuPnu. The isotopes considered here for which P/sub nu/ and or data (or both) were found in the literature are of americium (Am), curium (Cm), berkelium (Bk), californium (Cf), einsteinium (Es), fermium (Fm), and nobelium (No).

1985-01-01

107

Magnetic moments of "1"7"7Ta apd sup(181,182,187)Re states  

International Nuclear Information System (INIS)

The magnetic moments of "1"7"7Ta and sup(181,182,187)Re levels decaying via the K-forbidden transitions are measured. The nuclei studied are produced via the "1"7"7W and sup(181,182)Os and "1"8"7W #beta#-decay respectively. The magnetic moments have been measured using the method of the differential #gamma##gamma# angular correlations, perturbed by an external magnetic field. The following magnetic moments and lifetimes are obtained: for the 5/2"-1/2"-[541] "1"8"1Re level with excitation energy of 357 keV #mu#/#mu#sub(n)=2.00+-0.10, Tsub(1/2)=(76+-8)x10sup(-8) s; for the 186.4 keV 5/2"-1/2"-[541] "1"7"7Ta level #mu#/#mu#sub(n)=2.02+-0.13, Tsub(1/2)=(2.78+-0.09)x10sup(-6) s; for the 236 keV 2"- "1"8"2Re level #mu#/#mu#sub(n)=2.12+-0.08; for the 203 keV 9/2"- [514] "1"8"7Re level #mu#/#mu#sub(n)=5.04+-0.09.

1978-03-01

108

Excited leptons and quarks at #gamma##gamma#/#gamma#e colliders  

International Nuclear Information System (INIS)

We discuss the search of excited leptons and quarks with spin 1/2 at #gamma##gamma# and at #gamma#e colliders. We show that #gamma##gamma# colliders have important advantages for the observation of excited leptons and quarks in comparison with ee, ep, and pp colliders discussed in previous papers. These collisions give a simple test for the chirality of the l"*l#gamma# transition. The anomalous magnetic moment of excited leptons can be observed when its value is not too small. (orig.).

109

Electromagnetic properties of generalized Majorana particles  

Energy Technology Data Exchange (ETDEWEB)

We prove a theorem stating that a massive Majorana particle (a CPT-self-conjugate particle) with arbitrary spin J can possess only an anapole moment and multipoles of that. We also show that massless Majorana particles, except those of spin (1/2, do not have any single-photon electromagnetic form factor.

1989-02-20

110

Effect of large supersymmetric phases on Higgs production  

CERN Document Server

If the soft supersymmetry (SUSY) breaking masses and couplings are complex and cancellations do take place in the SUSY induced contributions to the fermionic electric dipole moments, then the CP- violating soft phases can drastically modify much of the known phenomenological pattern of the minimal supersymmetric standard model. In particular, the squark loop content of the dominant Higgs production mechanism at the large hadron collider, the gluon-gluon fusion mode, could be responsible for large corrections to the known cross sections. (15 refs).

2000-01-01

111

Australian Studies in Europe and the Omnipresent Elephant  

DEFF Research Database (Denmark)

Australian Studies has to undergo a transformation from its overtly literary focus to a more interdisciplinary approach, if it is to have a viable future. Rather than seeing this as a moment of unproductive stalemate, the article argues for the advantages in developing such a new focus. Also the article considers the historical evolution of Australian Studies in Europe.

2009-01-01

112

Association between meniscal tears and the peak external knee adduction moment and foot rotation during level walking in postmenopausal women without knee osteoarthritis: a cross-sectional study  

UK PubMed Central (United Kingdom)

IntroductionMeniscal injury is a risk factor for the development and progression of knee osteoarthritis, yet little is known about risk factors for meniscal pathology. Joint loading...Full Text Available

2008-01-01

113

(Photoexcited charge pair escape and recombination)  

Science.gov (United States)

Progress in four research areas on this project are summarized under the following topics: (1) Geminate charge pair recombination in hexane; (2) Fast current measurements resulting from excitation of charge transfer (CT) states; (3) Measurement of the dipole moment of excited states by DC conductivity; and (4) Charge separation at macroscopic interfaces between electron donor and acceptor solids. In a final section, personnel who have contributed to the project during the past budget period are described.

1990-01-01

114

Aurivillius phases of PbBi4Ti4O15 doped with Mn3+ synthesized by molten salt technique: Structure, dielectric, and magnetic properties  

International Nuclear Information System (INIS)

Doping of manganese (Mn3+/Mn4+) into the Aurivillius phase Pb1-xBi4+xTi4-xMnxO15 was carried out using the molten salt technique for various Mn concentrations (x=0, 0.2, 0.4, 0.6, 0.8, and 1). Single phase samples could be obtained in the composition range with x up to 0.6 as confirmed by X-ray and neutron diffraction analysis. Dielectric measurements show a peak at 801, 803, 813 and 850 K for samples with x=0, 0.2, 0.4, and 0.6, respectively, related to the ferroelectric transition temperature (Tc). The main contribution of the in-plane polarization for x?0.2 which was calculated from the atomic positions obtained by the structure analysis is the dipole moment in the Ti(1)O6 layer; however, for x?0.4 the polarization originates from the dipole moment in the Ti(2)O6 layer. Mn doping in the Pb1-xBi4+xTi4-xMnxO15 does not show any long range magnetic ordering. -- Graphical abstract: The dipole moment of TiO6 dependence of x ...

2011-05-01

115

Weak ferromagnets with integer and half-integer spin quantum numbers  

Energy Technology Data Exchange (ETDEWEB)

Experimental investigations are presented which demonstrate that the weak ferromagnets are special materials of a larger group of magnets which exhibit two magnetic ordering structures. In weak ferromagnets the main order is antiferromagnetic with a small ferromagnetic component existing in addition. On the other hand, materials in which other combinations of the two basic ordering structures coexist are also known. Common to all these non-collinear spin structures is that the moment components of the two magnetic structures are orthogonal. In the weak ferromagnets this orthogonality manifests already in the paramagnetic phase as a crossover from an isotropic to an anisotropic susceptibility with respect to the applied magnetic field: at high temperatures the antiferromagnetic Curie-Weiss law of the total moment is observed while for T->Tc crossover to a second Curie-Weiss law due to the weak ferromagnetic component occurs. For ...

2005-01-31

116

Topics in axion and neutrino physics, time reversal violation, and Higgs detection  

Energy Technology Data Exchange (ETDEWEB)

A number of systems which can elucidate physics beyond the standard model are investigated. The production of axions by a network of cosmic strings in the early universe is calculated. This allows an upper bound to be placed on the axion decay constant, and provides the preferred Peccei-Quinn symmetry breaking scale for axions to make up the dark matter of the universe. Models of neutrino mass arising from strong interactions are investigated. These models possess a massless up quark, thereby solving the strong CP problem. A systematic analysis of the contributions to time reversal violating atomic and molecular electric dipole moments is presented. Specific contributions from the supersymmetric standard model are calculated. The contributions arising from the QCD vacuum angle are also discussed. Prospects for detecting the axion by its long range coherent force are related to measurable electron dipole moments. A method for measuring neutrino ...

1993-12-31

117

Topics in axion and neutrino physics, time reversal violation, and Higgs detection  

International Nuclear Information System (INIS)

A number of systems which can elucidate physics beyond the standard model are investigated. The production of axions by a network of cosmic strings in the early universe is calculated. This allows an upper bound to be placed on the axion decay constant, and provides the preferred Peccei-Quinn symmetry breaking scale for axions to make up the dark matter of the universe. Models of neutrino mass arising from strong interactions are investigated. These models possess a massless up quark, thereby solving the strong CP problem. A systematic analysis of the contributions to time reversal violating atomic and molecular electric dipole moments is presented. Specific contributions from the supersymmetric standard model are calculated. The contributions arising from the QCD vacuum angle are also discussed. Prospects for detecting the axion by its long range coherent force are related to measurable electron dipole moments. A method for measuring neutrino ...

118

Socio-Academic Integrative Moments: Rethinking Academic and Social Integration among Two-Year College Students in Career-Related Programs  

Science.gov (United States)

College student persistence and dropout have been studied for decades, but little inquiry has focused on community college or private two-year college students. Although about half of first-time postsecondary students enroll in a two-year college, researchers understand little about why only approximately a quarter of these degree-seekers complete any degree five years after entrance (Rosenbaum, Deil-Amen, & Person, 2006). Models that exist have been generated primarily from research on residential, four-year college students. The present analysis uses rich qualitative data to excavate the potential of Tinto's Theory of Student Departure for understanding the dynamics of persistence for a more nontraditional group--two-year college commuting students. To better reflect how these students successfully cultivate feelings of belonging and competence, reinforce goal commitment, and access valuable social capital, a new conceptual fusion of the formerly distinct processes of academic ...

2010-12-01

119

Nuclear moments of neutron deficient iridium isotopes from laser spectroscopy  

Energy Technology Data Exchange (ETDEWEB)

Laser spectroscopy measurements have been performed on neutron deficient iridium isotopes. The hyperfine structure and isotope shift of the optical Ir I transition 5d{sup 7}6s{sup 24}F{sub 9/2} {sup {yields}} 5d{sup 7}6s6p {sup 6}F{sub 11/2} at 351.5 nm have been studied for the {sup 182-189}Ir, {sup 186}Ir{sup 1}m and {sup 191,193}Ir isotopes. The nuclear magnetic and quadrupole moments were obtained from the HFS measurements and the changes of the mean square charge radii from the IS measurements. A large mean square charge radius change between {sup 187}Ir and {sup 186}Ir and between {sup 186}Ir{sup 1}m and {sup 186}Ir{sup 1}g has been observed.

2000-08-15

120

Nuclear moments of neutron deficient iridium isotopes from laser spectroscopy  

International Nuclear Information System (INIS)

Laser spectroscopy measurements have been performed on neutron deficient iridium isotopes. The hyperfine structure and isotope shift of the optical Ir I transition 5d"76s"2"4F_9_/_2 "#-># 5d"76s6p "6F_1_1_/_2 at 351.5 nm have been studied for the "1"8"2"-"1"8"9Ir, "1"8"6Ir"1m and "1"9"1","1"9"3Ir isotopes. The nuclear magnetic and quadrupole moments were obtained from the HFS measurements and the changes of the mean square charge radii from the IS measurements. A large mean square charge radius change between "1"8"7Ir and "1"8"6Ir and between "1"8"6Ir"1m and "1"8"6Ir"1g has been observed.

2000-08-01

121

New short-range electromagnetic current in the deuteron  

International Nuclear Information System (INIS)

A new model for short-range isoscalar current in the deuteron and NN system is developed and tested on a variety of isoscalar magnetic observables such as the deuteron magnetic moment, magnetic form factor, and the circular polarization of photons at n"#->#p radiative capture at thermal neutron energies. The model for electromagnetic two-nucleon current proposed in the paper is based on generation of an intermediate dibaryon in the short-range NN interaction. This intermediate dibaryon, in turn, is treated within the new model for intermediate and short-range NN interaction recently proposed by the present authors. The transition current model developed here satisfies the current conservation relation by the construction. Our calculations have demonstrated that the new current model, using only one parameter (with a clear physical meaning), is able to describe, in very good agreement with the experimental data, three basic deuteron observables of magnetic type, ...

2007-02-01

122

Magnetic susceptibility and "1"5"1Eu Moessbauer studies on cubic ternary compounds: EuPtSi and EuPdSi  

International Nuclear Information System (INIS)

Two new equiatomic ternary compounds, EuPtSi and EuPdSi, have been synthesized and are found to crystallize in the cubic LaIrSi type structure. The magnetic susceptibility of both compounds follows Curie-Weiss behavior in the temperature range 10 to 300 K with an effective magnetic moment close to that of Eu"2"+ moment. The paramagnetic Curie temperatures are 5 K for EuPtSi and 9 K for EuPdSi. There is no clear indication of magnetic ordering in the susceptibility of both the compounds down to 4.2 K. However, "1"5"1Eu Moessbauer studies show a hyperfine split pattern in EuPtSi at 4.2 K indicating the onset of magnetic ordering. The "1"5"1Eu isomer shifts are temperature independent and are characteristic of the divalent Eu ion. All these results establish that the Eu ions are in a stable divalent state in these compounds. (orig.).

123

Low-temperature properties of ternary magnetic rare-earth transition-metal germanides with the Sc sub 5 Co sub 4 Ge sub 10 -type structure  

Energy Technology Data Exchange (ETDEWEB)

DC resistivity, dc magnetization, and specific heat of eight Sc{sub 5}Co{sub 4}Ge{sub 10}-type crystal-structure compounds R{sub 5}T{sub 4}Ge{sub 10} for R = Dy, Ho, Er, Tm, and T = Rh and Ir are presented. The resistivity, single-crystal magnetization, and specific-heat results show that in all those compounds, the magnetic moments order antiferromagnetically in the c direction at low temperature. However, in the Er and Tm compounds, the magnetizations along x-y hard directions do not show any anomalies above 2.0 K. This suggests that the ordered Er and Tm ions, which have positive quadrupole coefficients, interact with a crystal field that has an electronic potential valley along the c axis. The fitting of the hard axis magnetizations to Curie-Weiss law suggests that the resulting antiferromagnetic-like {theta} reflects the strength of the crystal-field torque on the magnetic moments rather than the strength of antiferromagnetic exchange.

1988-01-01

124

Low temperature properties of ternary magnetic rare earth transition metal germanides with the Sc/sub 5/Co/sub 4/Ge/sub 10/-type structure  

Energy Technology Data Exchange (ETDEWEB)

DC resistivity, dc magnetization, and specific heat of eight Sc/sub 5/Co/sub 4/Ge/sub 10/-type crystal structure compounds R/sub 5/T/sub 4/Ge/sub 10/ for R = Dy, Ho, Er, Tm, and T = Rh and Ir are presented. The resistivity, single crystal magnetization, and specific heat results show that in all those compounds, the magnetic moments order antiferromagnetically in the c direction at low temperature. However, in the Er and Tm compounds, the magnetizations along x-y hard directions do not show any anomalies above 2.0 K. This suggests that the ordered Er and Tm ions, which have positive quadrupole coefficients ..cap alpha../sub j/, interact with a crystal field that has an electronic potential valley along the c axis. The fitting of the hard axis magnetizations to Curie-Weiss law suggests that the resulting antiferromagnetic-like theta reflects the strength of the crystal field torque on the magnetic moments rather than the strength of ...

1988-07-01

125

Lifetimes of superdeformed nuclei in the mass region A {approx}150 with the Eurogam multidetector array; Durees de vie de noyaux superdeformes de la region de masse A {approx}150 mesurees avec le multicompteur Eurogam  

Energy Technology Data Exchange (ETDEWEB)

This work concerns the study of the nuclear superdeformation phenomenon in the rare earth region (A {approx} 150). The superdeformed (SD) states in Gadolinium and Dysprosium isotopes were produced via heavy-ion induced reactions and studied with the (EUROGAM EUROpean GAmma-ray Microscope) gamma multidetector array. Precise level attenuation method (DSAM). From the derived quadrupole moments, we find large differences in deformation between the yrast bands in neighbour nuclei explained in terms of the case of nuclei corresponding to an axis ratio of 2:1, the shell gaps are not fixed at a specific particle number and deformation. Furthermore the present results indicate that the deformations associated with identical bands are different supporting the picture that mass and deformation changes tend to compensate in SB bands with the same moments of inertia. (author). 114 refs.

1996-05-13

126

Interpreting the visible absorption bands of 1,4-(dihydroxy)-9,10-anthraquinone and its metal chelates.  

Science.gov (United States)

The visible absorption spectra of 1,4-(dihydroxy)-9,10-anthraquinone and of Co(II), Ni(II), Cu(II) and Zn(II) chelates have been studied in different organic solvents. This system provides a model for the anthracycline antibiotics and their metal chelates. The band structure of the spectrum has been determined using the second and fourth derivatives of the spectrum. The visible absorption band of the parent molecule can be assigned to a single electronic state with a reduced dipole moment in the excited state; structure in this band is ascribed to two overlapping vibrational progressions. In contrast, the dianion (hydroxy protons removed) shows a single electronic state with an increased dipole moment in the excited state; structure in this band can be assigned to a single vibrational progression. All of the metal chelates show spectra which are similar in appearance to that of the dianion although the identity of the metal determines the ...

1990-08-15

127

High Magnetic Field NMR Studies of LiVGe$_2$O$_6$, a quasi 1-D Spin $S = 1$ System  

CERN Document Server

We report $^{7}$Li pulsed NMR measurements in polycrystalline and single crystal samples of the quasi one-dimensional S=1 antiferromagnet LiVGe$_2$O$_6$, whose AF transition temperature is $T_{\\text{N}}\\simeq 24.5$ K. The field ($B_0$) and temperature ($T$) ranges covered were 9-44.5 T and 1.7-300 K respectively. The measurements included NMR spectra, the spin-lattice relaxation rate ($T_1^{-1}$), and the spin-phase relaxation rate ($T_2^{-1}$), often as a function of the orientation of the field relative to the crystal axes. The spectra indicate an AF magnetic structure consistent with that obtained from neutron diffraction measurements, but with the moments aligned parallel to the c-axis. The spectra also provide the $T$-dependence of the AF order parameter and show that the transition is either second order or weakly first order. Both the spectra and the $T_1^{-1}$ data show that $B_0$ has at most a small effect on the alignment of the AF ...

2001-01-01

128

Generalized Gas Dynamic Equations for Microflows  

CERN Document Server

n an early approach, we proposed a kinetic model with multiple translational temperature [K. Xu, H. Liu and J. Jiang, Phys. Fluids {\\bf 19}, 016101 (2007)], to simulate non-equilibrium flows. In this paper, instead of using three temperatures in $x-$, $y-$, and $z$-directions, we are going to further define the translational temperature as a second-order symmetric tensor. Based on a multiple stage BGK-type collision model and the Chapman-Enskog expansion, the corresponding macroscopic gas dynamics equations in three-dimensional space will be derived. The zeroth-order expansion gives the 10 moment closure equations of Levermore [C.D. Levermore, J. Stat. Phys {\\bf 83}, pp.1021 (1996)]. To the 1st-order expansion, the derived gas dynamic equations can be considered as a regularization of Levermore's 10 moments equations. The new gas dynamic equations have the same structure as the Navier-Stokes equations, but the stress strain relationship in ...

2008-01-01

129

Frequency analysis of daily rainfall in Han River basin based on regional L-moments algorithm  

Energy Technology Data Exchange (ETDEWEB)

At-site and regional frequency analyses of annual maximum 1-, 2-, and 3-days rainfall in Han River basin was performed and compared based on the regional L-moments algorithm. To perform regional frequency analysis, Han River basin was subdivided into 3 sub-basins such as South Han River, North Han River, and downstream regions. For each sub-basin, the discordancy and homogeneity tests were performed. As the results of goodness of fit tests, lognormal model was selected as an appropriate probability distribution for both South Han River and downstream regions and gamma-3 model for North Han River region. From Monte Carlo simulation, RBIAS and RRMSE of the estimated quantiles from regional frequency analysis and at-site frequency analysis were calculated and compared each other. Regional frequency analysis shows less RRMSE of the estimated quantiles than at-sites frequency analysis in overall return periods. The differences of RRMSE between two approaches increase as ...

2001-04-30

130

Fluctuation properties of strength function phenomena: A model study  

Energy Technology Data Exchange (ETDEWEB)

We study fluctuation properties of strength function phenomena by employing a quantum mechanical model where a single parent state couples with a large number of background states. The background system is devised in such a way that the classical dynamics of the system may show a regular, an irregular, or a chaotic character as a function of a single parameter. The coupling of the parent state to the background states produces a fragmentation of the parent state, giving rise to a strength function phenomenon. We study various measures of the strength function that characterize its bulk structure or fluctuation properties. They include energy moments, strength distribution, fractal dimensions of the strength function, and Fourier transform of the autocorrelation function. Some of these measures, such as strength distribution or Fourier transform of the autocorrelation function, reflect characteristic aspects of the dynamics of the background system, i.e., if they ...

1997-07-01

131

Ferroelectric and magnetic properties of Ho{sub 2}CuTiO{sub 6} double perovskite  

Energy Technology Data Exchange (ETDEWEB)

Ho{sub 2}CuTiO{sub 6} double pervoskite is synthesized by solid state reaction method and the phase formation was confirmed by X-ray diffraction. Ho{sub 2}CuTiO{sub 6} crystallizes in space group P63 cm and are isostructural in AMnO{sub 3} structure. We have investigated the effect of the presence of a magnetic ion (Ho{sup 3+}{approx}10.4{mu}{sub B}) in Ho{sub 2}CuTiO{sub 6}, on the magnetic properties, compared to that of an isostructural double perovskite containing Y-ion (non-magnetic), i.e., Y{sub 2}CuTiO{sub 6}. Magnetization measurements on Ho{sub 2}CuTiO{sub 6} showed paramagnetic moment of 0.026{mu}{sub B}/Ho at room temperature in an applied field of 7 T although no saturation is observed at room temperature, whereas, at 5 K, the paramagnetic moment was 0.3{mu}{sub B}/Ho in the same field. Since this compound is non-centrosymmetric, it is of interest to look into the possibility of realizing multiferroicity (coexistence of magnetic and ...

2006-08-15

132

Element-selective thermal x-ray magnetic circular dichroism study through the magnetic compensation temperature of Ho{sub 6}Fe{sub 23}  

Science.gov (United States)

We present an x-ray magnetic circular dichroism (XMCD) study performed on both Ho{sub 6}Fe{sub 23} and Y{sub 6}Fe{sub 23} compounds as a function of the temperature. The combined analysis of both Fe K-edge and Ho L{sub 2,3}-edge XMCD spectra recorded through the magnetic compensation transition allows us to disentangle the thermal dependence of both Fe and Ho magnetic moments in Ho{sub 6}Fe{sub 23}. In addition, contributions from Ho ions to the Fe K-edge XMCD signals and, conversely, from Fe ions to the Ho L{sub 2,3}-edge XMCD spectra have been clearly identified. These extra contributions, arising from the strong Fe(3d)-Ho(5d) hybridization, have been isolated from the spectra and correlated with the magnetic state of both Ho and Fe ions surrounding the absorbing site. The influence of these contributions to the values of the orbital and spin moments derived by using sum rule analysis is also shown.

2005-09-01

133

Effect of seafloor instability on offshore pile foundations  

Energy Technology Data Exchange (ETDEWEB)

A modified boundary element approach was used to analyze the response of offshore piles subjected to external soil movements. The computer model employed to solve the pile-soil problem was able to model pile head and tip loading, and loading caused by lateral movement of soil. A nonlinear pile-soil interface element with the ability to represent a hardening or softening plastic response prior to reaching an ultimate state was incorporated. With the program, 4 failure modes can be determined: flow of the soil slide past an intact stationary pile; rotation of the pile with the soil at failure along the full pile length; translation of the pile with the sliding soil, resulting in failure of the supporting soil; and the long-pile mode, in which the maximum bending moment in the pile reaches the yield moment of the pile before complete development of the other 3 modes. Theoretical solutions for a realistic hypothetical offshore pile subjected to ...

1991-01-01

134

Consistency of the phenomenological theories of wave-type heat transport with the hydrodynamics of a phonon gas  

International Nuclear Information System (INIS)

Various phenomenological theories of wave-type heat transport, which can be interpreted as the models of an isotropic rigid heat conductor with an internal vector state variable, have been proposed in the literature with the objective to describe the second sound propagation in dielectric crystals. The aim of this paper is to analyze the relation between these phenomenological approaches and the phonon gas hydrodynamics. The four-moment phonon gas hydrodynamics based on the maximum entropy closure of the moment equations with nonlinear isotropic phonon dispersion relation is considered for this purpose. We reformulate the equations of this hydrodynamics in terms of energy and quasi-momentum as the primitive fields and subsequently demonstrate that, from the macroscopic point of view, they can be understood as describing the reference model of an isotropic rigid heat conductor with quasi-momentum playing the role of the internal vector state ...

2010-09-24

135

Compressed Counting  

CERN Document Server

Counting is among the most fundamental operations in computing. For example, counting the pth frequency moment has been a very active area of research, in theoretical computer science, databases, and data mining. When p=1, the task (i.e., counting the sum) can be accomplished using a simple counter. Compressed Counting (CC) is proposed for efficiently computing the pth frequency moment of a data stream signal A_t, where 0= 0, which includes the strict Turnstile model as a special case. For natural data streams encountered in practice, this restriction is minor. The underly technique for CC is what we call skewed stable random projections, which captures the intuition that, when p=1 a simple counter suffices, and when p = 1+/\\Delta with small \\Delta, the sample complexity of a counter system should be low (continuously as a function of \\Delta). We show at small \\Delta the sample complexity (number of projections) k = O(1/\\epsilon) instead ...

2008-01-01

136

Atomic spectroscopy study of nuclear properties of francium and cesium isotopes; Etude par spectroscopie atomique de proprietes nucleaires d'isotopes de francium et de cesium  

Energy Technology Data Exchange (ETDEWEB)

This work is based on the study of cesium ({sup 118,146}Cs) and francium ({sup 207-213}Fr,{sup 220-228}Fr) isotopes by hyperfine atomic spectroscopy and on the interpretation of these results from the nuclear physics point of view. The measured nuclear quantities are: the spin, the magnetic moment, the electric quadrupole moment and the mean square charge radius. The experimental method which is based on hyperfine optical pumping with a tunable laser, followed by magnetic analysis of the atoms is described in the first part. Results related to atomic physics are also presented. In the second part, these data are interpreted in the framework of nuclear models. The deformation of light cesium isomers are compared to values obtained from a theoretical self-consistent calculation. Heavy francium isotopes are situated in an area where the existence of static octupole deformations have been predicted. The odd-even staggering measured on the mean ...

1986-04-15

137

[Method of determining tissue renin activity using heterologous serum].  

Science.gov (United States)

The authors described a method for determination of tissue renin activity with heterologous substrate. The preparation of the substrate was performed at several stages: salting with amonium sulfate; dialisis of the precipitate till complete separation of amonium sulfate molecules; distruction of angiotensinases by interchangeble souring and alcalization of the medium; lyophylization of the pure substrate. The obtained renin-substrate was preserved in ampules and its usage had a series of advantages--duration, economic, a possibility for standartization of the determination, etc., which were described in details in the article. The described in details also the quantitative determination of the renin activity in the tissues (renal and cerebral) with the help of the obtained substrate as the moments, modiied by the authors, were indicated. PMID:436712

1979-01-01

138

The Proton structure function F(2) in the resonance region  

Energy Technology Data Exchange (ETDEWEB)

Unique measurement of the proton structure function F2 in a wide two-dimensional region of x and Q**2 has been reported. The accessible kinematics covers entire resonance region up to W=2.5 GeV in the Q**2 interval from 0.1 to 4.5 GeV**2. Obtained data allowed for the first time an evaluation of moments of the structure function F2 directly from experimental data as well as an intensive study of the Bloom-Gilman duality phenomenon.

2003-06-01

139

The ACR Model: A Multivariate Dynamic Mixture Autoregression  

British Library Electronic Table of Contents (United Kingdom)

Abstract This paper proposes and analyses the autoregressive conditional root (ACR) time-series model. This multivariate dynamic mixture autoregression allows for non-stationary epochs. It proves to be an appealing alternative to existing nonlinear models, e.g. the threshold autoregressive or Markov switching class of models, which are commonly used to describe nonlinear dynamics as implied by arbitrage in presence of transaction costs. Simple conditions on the parameters of the ACR process and its innovations are shown to imply geometric ergodicity, stationarity and existence of moments. Furthermore, consistency and asymptotic normality of the maximum likelihood estimators are established. An application to real exchange rate data illustrates the analysis.

2008-01-01

140

Reactor Neutrino Experiments  

CERN Document Server

Precisely measuring $\\theta_{13}$ is one of the highest priority in neutrino oscillation study. Reactor experiments can cleanly determine $\\theta_{13}$. Past reactor neutrino experiments are reviewed and status of next precision $\\theta_{13}$ experiments are presented. Daya Bay is designed to measure $\\sin^22\\theta_{13}$ to better than 0.01 and Double Chooz and RENO are designed to measure it to 0.02-0.03. All are heading to full operation in 2010. Recent improvements in neutrino moment measurement are also briefed.

2007-01-01

141

Quark-hadron duality in structure functions  

Energy Technology Data Exchange (ETDEWEB)

I review recent developments in quark-hadron duality in inclusive electron-nucleon scattering. Matrix elements of twist-4 operators extracted from moments of the spin-dependent g1 structure function suggest that duality violating higher twists are small above Q2 {approx} 1 GeV2. The x dependence of local duality is analyzed within a quark model framework, and mechanisms are identified for spin-flavor symmetry breaking which underpin the behavior of structure functions at large x.

2004-10-01

142

Quantum Impurities in the Two-Dimensional Spin One-Half Heisenberg Antiferromagnet  

CERN Document Server

The study of randomness in low-dimensional quantum antiferromagnets is at the forefront of research in the field of strongly correlated electron systems, yet there have been relatively few experimental model systems. Complementary neutron scattering and numerical experiments demonstrate that the spin-diluted Heisenberg antiferromagnet La2Cu(1-z)(Zn,Mg)zO4 is an excellent model material for square-lattice site percolation in the extreme quantum limit of spin one-half. Measurements of the ordered moment and spin correlations provide important quantitative information for tests of theories for this complex quantum-impurity problem.

2002-01-01

143

Properties of the quadrupole glass phase in the presence of an external field gradient  

Energy Technology Data Exchange (ETDEWEB)

A model of a solid disordered ortho-parahydrogen mixture with infinite long-range interaction J/sub ij/ between orthomolecules distributed in accordance with a normal law with first moment J/sub 0/ is investigated. It is shown that the introduction of an external electric field gradient ..gamma.. can give rise to a phase transition to an orientational phase. The possible existence of an orientational glass phase is established. The influence of the degeneracy of the hydrogen orthomolecules on the low-temperature thermal properties of these systems is demonstrated, and a condition of stability of the replica-symmetric solution is established. At low temperatures, this solution is stable for a large value of ..gamma.. or J/sub 0/.nctio

1987-11-01

144

Outage Probability of Diversity Combining Receivers in Arbitrarily Fading Channels  

CERN Document Server

We propose a simple and accurate method to evaluate the outage probability at the output of arbitrarily fading L-branch diversity combining receiver. The method is based on the saddlepoint approximation, which only requires the knowledge of the moment generating functions of the signal-to-noise ratio at the output of each diversity branch. In addition, we show that the obtained results reduce to closed-form expressions in many particular cases of practical interest. Numerical results illustrate a very high accuracy of the proposed method for practical outage values and for a large mixture of fading and system parameters.

2011-01-01

145

On the validity of the pseudo-spin concept for axially symmetric deformed nuclei  

International Nuclear Information System (INIS)

The average single-particle field shows a very small pseudo-spin-orbit splitting in the pseudo-spin representation. If this splitting is neglected, pseudo-spin becomes a good quantum number and the resulting scheme (the pseudo-Nilsson model) has a very simple interpretation. The pseudo-spin symmetry embodied in the realistic deformed average field is explored by comparing the single-particle energies and wave functions of the deformed Woods-Saxon model with the corresponding results of the pseudo-Nilsson model. The scheme is used to calculate the magnetic moments of deformed odd-A nuclei of the rare-earth region. (orig.).

146

On the magnetic behaviour of REBa_2F_7 compounds (RE=Eu, Dy, Ho, Er, Tm and Yb)  

International Nuclear Information System (INIS)

The DC magnetic susceptibility of the REBa_2F_7 compounds was measured by a SQUID magnetometer in the temperature range 5-300 K. Except for Eu, the other compounds show either Curie law or Curie-Weiss law with relatively small values of paramagnetic Curie temperature, #theta#_p, with effective magnetic moments in the range expected of electronic ground state of the trivalent rare earth ion with appropriate J value. The behaviour of Eu is complex. (orig.).

147

Occurrence of magnetism in superconductors  

Science.gov (United States)

We discuss how magnetic phenomena affect superconductivity in simple metals, transition metals and alloys thereof, and dilute Rare-Earth alloys. It is shown both qualitatively and quantitatively that superconductors are sensitive probes for studying itinerant spin excitations, local spin excitations associated with nearly magnetic impurities, the effect of the atomic environment on the stability of local magnetic moments, and the nature of the spin order in Rare-Earth alloys. Also, we discuss how magnetic impurities can be used to study the electronic configuration which is responsible for superconductivity in Laves-phase crystals like A-15 compounds and ..beta..-W crystals, for example.

1970-12-14

148

Neutron diffraction study of 5f itinerant antiferromagnet UPtGa{sub 5} and UNiGa{sub 5}  

Energy Technology Data Exchange (ETDEWEB)

Magneto-striction and magnetic form factors in 5f itinerant antiferromagnets UNiGa{sub 5} and UPtGa{sub 5} are studied by means of neutron scattering. Remarkable magneto-striction was observed around T{sub N}, indicating large spin-orbit coupling in the itinerant system. The orbital magnetic moment is found to be strongly suppressed due to the hybridization of uranium 5f with Ga-4p electron.

2003-05-01

149

Nature of the magnetic susceptibility of dysprosium. Paramagnetic susceptibility of dysprosium - yttrium alloys  

International Nuclear Information System (INIS)

The paramagnetic susceptibility of single crystals of dysprosium-yttirum alloys is measured in the basal plane and along the hexagonal axis. It is shown that the susceptibility of the alloys obeys the Curie-Weiss law, the effective magnetic moments allong the different directions being the same and the paramagnetic Curie temperatures being different. The difference between the paramagnetic Curie temperatures in the basal plane and along the hexagonal axis is independent of the dysprosium concentration in the alloy. As a comparison with the theoretical models of magnetic anisotropy shows, this is an indication that the magnetic anisotropy of dysprosium - yttrium alloys is of a single-ion nature.

1976-01-01

150

Hyperfine structure studies with the COMPLIS facility  

International Nuclear Information System (INIS)

COMPLIS is an experimental facility designed to carry out spectroscopic studies on radioisotopes produced by disintegration of elements available at CERN's Booster-ISOLDE on-line isotope separator. During recent series of experimental runs, hyperfine structure measurements have yielded information on nuclear moments and deformations of platinum and iridium isotopes. For the first time, population by #alpha#-decay from Hg was exploited to investigate "1"7"8"-"1"8"1Pt--the most neutron-deficient Pt isotopes yet studied. Successful measurements have recently been carried out on "1"8"2"-"1"8"9Ir.

1998-12-16

151

Excited leptons and quarks at. gamma. gamma. /. gamma. e colliders  

Energy Technology Data Exchange (ETDEWEB)

We discuss the search of excited leptons and quarks with spin 1/2 at {gamma}{gamma} and at {gamma}e colliders. We show that {gamma}{gamma} colliders have important advantages for the observation of excited leptons and quarks in comparison with ee, ep, and pp colliders discussed in previous papers. These collisions give a simple test for the chirality of the l{sup *}l{gamma} transition. The anomalous magnetic moment of excited leptons can be observed when its value is not too small. (orig.).

1992-02-06

152

Electron and phonon properties of 25 A-15 superconductors obtained from heat capacity measurements  

International Nuclear Information System (INIS)

We review 25 specific heat measurements performed in Geneva on binary and pseudo-binary A-15 compounds. The rather extended temperature range allows us to make reliable estimates of several moments of the phonon spectrum which are required in the theory of superconductivity. The Tsub(c) expression of Allen and Dynes can then be used consistently to estimate the microscopic parameters lambda, eta, Nsub(bs) (Esub(F)), etc. The broad range of values reviewed permits to establish significant correlations between the parameters in stoichiometric and ordered compounds. (orig.).

153

Effective Constraints for Quantum Systems  

CERN Document Server

An effective formalism for quantum constrained systems is presented which allows manageable derivations of solutions and observables, including a treatment of physical reality conditions without requiring full knowledge of the physical inner product. Instead of a state equation from a constraint operator, an infinite system of constraint functions on the quantum phase space of expectation values and moments of states is used. The examples of linear constraints as well as the free non-relativistic particle in parameterized form illustrate how standard problems of constrained systems can be dealt with in this framework.

2008-01-01

154

Distribution amplitudes of {sigma} and {lambda} and their electromagnetic form factors  

Energy Technology Data Exchange (ETDEWEB)

Based on QCD conformal partial wave expansion to leading order conformal spin accuracy, we present the light-cone distribution amplitudes (DAs) of {sigma} and {lambda} baryons up to twist 6. It is concluded that fourteen independent DAs are needed to describe the valence three-quark states of the baryons at small transverse separations. The nonperturbative parameters relevant to the DAs are determined within the framework of QCD sum rule method. With the obtained DAs, a simple investigation on the electromagnetic form factors of these baryons are given. The magnetic moments of the baryons are estimated by fitting the magnetic form factor with the dipole formula.

2009-04-15

155

Deformation change in light iridium nuclei from laser spectroscopy  

Energy Technology Data Exchange (ETDEWEB)

Laser spectroscopy measurements have been performed on neutron-deficient and stable Ir isotopes using the COMPLIS experimental setup installed at ISOLDE-CERN. The radioactive Ir atoms were obtained from successive decays of a mass-separated Hg beam deposited onto a carbon substrate after deceleration to 1kV and subsequently laser desorbed. A three-color, two-step resonant scheme was used to selectively ionize the desorbed Ir atoms. The hyperfine structure (HFS) and isotope shift (IS) of the first transition of the ionization path 5d{sup 7}6s{sup 24}F{sub 9/2}{yields}5d{sup 7}6s6p{sup 6}F{sub 11/2} at 351.5nm were measured for {sup 182-189}Ir, {sup 186}Ir{sup m} and the stable {sup 191,193}Ir. The nuclear magnetic moments {mu}{sub I} and the spectroscopic quadrupole moments Q{sub s} were obtained from the HFS spectra and the change of the mean square charge radii from the IS measurements. The sign of {mu}{sub I} was experimentally determined for ...

2006-12-15

156

Coordination compounds of oxovanadium(4), nickel(2) and copper(2) with bis-(salicyliden)-thiocarbazide  

International Nuclear Information System (INIS)

A reaction of aqueous-methanol solutions of thiocarbazide and salycilic aldehyde, taken in a molal ratio of 1:2 on the matrix of oxovanadium(VO) in the presence of aqueous ammonium results in a coordination compound of the VC_1_5H_1_2N_4O_3S composition. Similar compounds are obtained with salts of nickel(2) and copper(2). Complexes of oxovanadium(4) and copper(2) have effective magnetic moments normal for systems with a spin of 1/2. The compound with nickel is diamagnetic. These data agree with the configuration of the coordination compounds obtained.

157

Compressive and Torsional Buckling Behavior of Carbon Nanotube Bundles  

International Nuclear Information System (INIS)

The compressive and torsional buckling behavior of carbon nanotube bundles at room temperature is examined with classical molecular dynamics simulation. The critical compressive load and stiffness of a single carbon nanotube in the bundle are found to be similar to those of individual carbon nanotubes. However, the critical torsional moment and stiffness of a single carbon nanotube in the bundle are found to be higher than those of individual carbon nanotubes. In addition, this study demonstrates that van der Waals interactions between the nanotubes in the bundle significantly affect the critical compressive load of the nanotube bundle.

2007-08-01

158

Clean air status report. Statistical analysis of pollution, 1966 through 1982  

Energy Technology Data Exchange (ETDEWEB)

Air pollution abatement measures are being intensified at the moment: Power plants and district heating systems are being retrofitted with high-efficiency desulphurisation and NO/sub 2/ reduction systems, the 3rd amendment of the Clean Air Technical Guide sets more rigid emission limits, and unleaded petrol and catalysts will significantly reduce car exhaust emissions. The author presents pollutant balances from 1966 to 1982 to contradict the popular notion that pollutant emitters formerly failed to take preventive measures.

1986-04-01

159

Chiral solitons in nuclei: Electromagnetic form factors  

Science.gov (United States)

We calculate the electromagnetic form factors of a bound proton. The chiral quark-soliton model provides the quark and antiquark substructure of the proton, which is embedded in nuclear matter. This procedure yields significant modifications of the form factors in the nuclear environment. The sea quarks are almost completely unaffected, and serve to mitigate the valence quark effect. In particular, the ratio of the isoscalar electric to the isovector magnetic form factor decreases by 20% at Q{sup 2}=1 GeV{sup 2} at nuclear density, and we do not see a strong enhancement of the magnetic moment.

2004-12-01

160

An efficient control variate method for pricing variance derivatives  

British Library Electronic Table of Contents (United Kingdom)

This paper studies the pricing of variance swap derivatives with stochastic volatility by the control variate method. A closed form solution is derived for the approximate model with deterministic volatility, which plays the key role in the paper, and an efficient control variate technique is therefore proposed when the volatility obeys the log-normal process. By the analysis of moments for the underlying processes, the optimal volatility function in the approximate model is constructed. The numerical results show the high efficiency of our method; the results coincide with the theoretical results. The idea in the paper is also applicable for the valuation of other types of variance swap, options with stochastic volatility and other financial derivatives with multi-factor models.

2010-01-01

161

Magnetism of the Ni(110) and Ni(100) surfaces: local-spin-density-functional calculations using the thin-slab linearized augmented-plane-wave method  

International Nuclear Information System (INIS)

Results of self-consistent local-spin-density-functional calculations are reported for the first time for the Ni(110) surface, represented by one-, three-, and five-layer slabs. Calculations for one- and five-layer slabs of Ni(100) are also reported. The behavior of the surface magnetization with varying slab thickness elucidates the nature and origin of the surface magnetic moment. We predict a 13% enhancement of the Ni(110) surface magnetic moment compared to the bulk value. For the Ni(100) surface, we find a smaller surface enhancement about 7%, compared to bulk, which agrees with the results of Jepsen et al. The enhancement of surface magnetic moments on Ni(100) and Ni(110) surfaces is attributed to s-d dehybridization at the surface and to the presence of electrostatic shifts required to maintain layer-by-layer charge neutrality. We find that the total d-electron charge is the same in each layer, which contradicts the ...

162

Magnetic properties of Nd_2CuO_4-type R_2CuO_4 (R=Y, Dy, Ho, Er, Tm) synthesized under high pressure: Weak ferromagnetism of Y_2CuO_4  

International Nuclear Information System (INIS)

Magnetization of R_2CuO_4 (R=Y, Dy, Ho, Er, Tm) crystallizing in the Nd_2CuO_4-type (T') structure has been measured between 4 and 300 K. In Y_2CuO_4 antiferromagnetic ordering of Cu"2"+ spins at 260 K has been detected clearly, without being interfered with by the paramagnetic contribution of rare-earth elements as in the other compositions. Weak ferromagnetic behavior with a moment of 9x10"-"4 #mu#_B/Cu accompanies the antiferromagnetic transition. Dy"3"+, Ho"3"+, Er"3"+, and Tm"3"+ ions obey the Curie-Weiss law at relatively high temperatures, and the effective moments are in good agreement with the values anticipated from their lowest multiplet levels. Various types of deviations from the law occur at low temperatures. Specifically, a sharp kink possibly suggesting antiferromagnetic ordering of the Dy"3"+ moments has been found at 7 K. Anomalies around 200 K for Ho_2CuO_4 and Er_2CuO_4 reflect the weak ferromagnetic ...

1990-10-01

163

Large perpendicular magnetic anisotropy of ultrathin Ru and Rh films on a NiAl(001) surface  

International Nuclear Information System (INIS)

Using the full potential linearized augmented plane wave (FLAPW) method, the magnetic properties of two-dimensional Ru and Rh monolayers (MLs) on a NiAl(001) surface have been investigated. It has been found that free standing one monolayer Ru and Rh films have ferromagnetic ground state with magnetic moments of 2.21 and 1.48 #mu#_B, respectively. The ferromagnetism is still observed even on a Ni terminated NiAl(001) surface, while no magnetic state is found on an Al terminated surface. The calculated magnetic moments of Ru and Rh atoms are 1.56 and 0.88 #mu#_B, respectively. In addition, an induced magnetic moment in surface Ni is observed. It has been found that the free standing Ru film has perpendicular magnetization to the film surface with a magnetocrystalline anisotropy (MCA) energy of 0.66 meV/atom, while an in-plane MCA energy of 0.37 meV/atom is achieved in Rh film. Very interestingly, we find that both ...

2010-10-27

164

Element selective X-ray magnetic circular and linear dichroisms in ferrimagnetic yttrium iron garnet films  

Energy Technology Data Exchange (ETDEWEB)

X-ray magnetic circular dichroism (XMCD) was used to probe the existence of induced magnetic moments in yttrium iron garnet (YIG) films in which yttrium is partly substituted with lanthanum, lutetium or bismuth. Spin polarization of the 4d states of yttrium and of the 5d states of lanthanum or lutetium was clearly demonstrated. Angular momentum resolved d-DOS of yttrium and lanthanun was shown to be split by the crystal field, the two resolved substructures having opposite magnetic polarization. The existence of a weak orbital moment involving the 6p states of bismuth was definitely established with the detection of a small XMCD signal at the Bi M{sub 1}-edge. Difference spectra also enhanced the visibility of subtle changes in the Fe K-edge XMCD spectra of YIG and {l_brace}Y, Bi{r_brace}IG films. Weak natural X-ray linear dichroism signatures were systematically observed with all iron garnet films and with a bulk YIG single crystal cut ...

2009-12-15

165

Effect of magnetic field and pressure on U(Ni_1_-_xPd_x)_2Si_2 single crystals  

International Nuclear Information System (INIS)

Single crystals of U(Ni_1_-_xPd_x )_2Si_2 for x = 0.05, 0.10 and 0.15 have been grown. Magnetization and electrical resistivity measurements were performed in a wide range of temperatures, magnetic fields and high pressures in order to study stability of magnetic phases in the solid solutions between UNi_2Si_2 and UPd_2Si_2 with a special emphasis on the type of ground state. In UPd_2Si_2 the simple AFI-type antiferromagnetic structure of U moments is observed at low temperatures. UNi_2Si_2 adopts the uncompensated AF structure (UAF) with the ++- stacking of U moments along the c-axis and consequently this compound exhibits a spontaneous magnetization corresponding to 1/3 of the U moment. The substitution of Pd for Ni leads to a rapid decay of the spontaneous magnetization. The evolution of magnetization and electrical resistivity behavior with Pd doping is tentatively attributed to the coexistence of the AF-I and UAF ...

2002-07-01

166

Deformation change in light iridium nuclei from laser spectroscopy  

International Nuclear Information System (INIS)

Laser spectroscopy measurements have been performed on neutron-deficient and stable Ir isotopes using the COMPLIS experimental setup installed at ISOLDE-CERN. The radioactive Ir atoms were obtained from successive decays of a mass-separated Hg beam deposited onto a carbon substrate after deceleration to 1kV and subsequently laser desorbed. A three-color, two-step resonant scheme was used to selectively ionize the desorbed Ir atoms. The hyperfine structure (HFS) and isotope shift (IS) of the first transition of the ionization path 5d"76s"2"4F_9_/_2#->#5d"76s6p"6F_1_1_/_2 at 351.5nm were measured for "1"8"2"-"1"8"9Ir, "1"8"6Ir"m and the stable "1"9"1","1"9"3Ir. The nuclear magnetic moments #mu#_I and the spectroscopic quadrupole moments Q_s were obtained from the HFS spectra and the change of the mean square charge radii from the IS measurements. The sign of #mu#_I was experimentally determined for the first time for the masses 182#=#+0.2 for ...

2006-12-01

167

Wave electromagnetic fields induced by instantaneous braking of charges  

International Nuclear Information System (INIS)

Exact expressions for wave electromagnetic fields during instantaneous braking of two differently charged discs uniformly moving in the opposite directions have been derived. Analysis of their properties has been made. It is shown that electromagnetic wave fields during instantaneous braking of charges have a tearing nature and the Umov-Poynting theorem in the integral form is realized only at a certain value of parameter #alpha# which determines charges rates at the moment of braking. The value of parameter #alpha# is in the ranges from 0.5 to #sq root#3/2. The wave field is formed already in the absence of motion of charged discs. It is a good example confirming the conclusion that in the case of nonstationary electromagnetic fields, performance of reaction force of the wave field can differ fram radiation energy.

168

Tunneling magnetoresistance from a symmetry filtering effect  

International Nuclear Information System (INIS)

This paper provides a brief overview of the young, but rapidly growing field of spintronics. Its primary objective is to explain how as electrons tunnel through simple insulators such as MgO, wavefunctions of certain symmetries are preferentially transmitted. This symmetry filtering property can be converted into a spin-filtering property if the insulator is joined epitaxially to a ferromagnetic electrode with the same two-dimensional symmetry parallel to the interface. A second requirement of the ferromagnetic electrodes is that a wavefunction with the preferred symmetry exists in one of the two spin channels but not in the other. These requirements are satisfied for electrons traveling perpendicular to the interface for Fe-MgO-Fe tunnel barriers. This leads to a large change in the resistance when the magnetic moment of one of the electrodes is rotated relative to those of the other electrode. This large tunneling magnetoresistance effect is being used as the ...

2008-04-01

169

Transformed Governance and the Education for All-Fast Track Initiative. Policy Brief 2010-02  

Science.gov (United States)

The Education for All-Fast Track Initiative (FTI) grew out of the "New Focus on Education for All" communique of the G-8 when Canada hosted the summit in 2002 at Kananaskis. As Canada prepares again to host the G-8, and Korea assumes leadership of the newly-empowered G-20, it is a valuable moment to revisit and re-think the current global education architecture. By adopting some of the recommendations from the recent independent evaluation of the FTI and borrowing some lessons from global partnerships in other sectors, the FTI could set a new course toward the achievement of universal basic education. The FTI should broaden and strengthen the role of diverse stakeholders from developing countries and civil society in its governance structure in order to fully harness the energies of these stakeholders in resource mobilization and effective implementation. (Contains 9 endnotes.)

2010-05-01

170

The temporal distribution of past and future autobiographical events across the lifespan.  

Science.gov (United States)

Knowledge and awareness of past and future autobiographical events may be mediated by a common system that supports intentional, goal-directed behavior. The purpose of this study was to assess the correspondence of past and future autobiographical thought. In Experiment 1, 300 undergraduates aged 19 years generated and assigned dates to past and f utu re autobiographical events. Thetemporal distribution of past events replicated a power function for retention as has been described in past research. The intention function of future autobiographical events fit the inverse of this same power function, reflecting a temporality of past and future mental time travel centered around the present moment. In Experiment 2, these findings were extended to young, middle-aged, and older groups. These data provide empirical support for the notion that thinking outside of "now" is mediated by a common system, regardless of whether one is thinking about the past or the future. ...

2006-12-01

171

The physics of tachyons. Part 4. Tachyon electrodynamics  

Energy Technology Data Exchange (ETDEWEB)

A new formulation of the theory of tachyons using the same two postulates as in special relativity is applied to the electrodynamics of material media. A discussion of Lagrange`s equations and Hamilton`s equations for `classical` charged tachyons shows that such a formalism is a viable approach. An essay is included on why tachyons can be considered to be localised particles for the purpose of calculations. Tachyonic transformations of the electromagnetic fields D, P, H and M are shown to be the same as for bradyonic transformations. Examples discussed include the electric dipole moment of a tachyonic current loop, constitutive equations, polarisation in tachyonic dielectric materials and the velocity of light in tachyonic dielectric media. This is followed by discussions of the collision energy loss for charged tachyons interacting with a material medium and a mathematical proof that tachyons cannot emit Cherenkov radiation when passing through a bradyonic ...

1998-12-31

172

The physics of tachyons. Part 4. Tachyon electrodynamics  

International Nuclear Information System (INIS)

A new formulation of the theory of tachyons using the same two postulates as in special relativity is applied to the electrodynamics of material media. A discussion of Lagrange's equations and Hamilton's equations for 'classical' charged tachyons shows that such a formalism is a viable approach. An essay is included on why tachyons can be considered to be localised particles for the purpose of calculations. Tachyonic transformations of the electromagnetic fields D, P, H and M are shown to be the same as for bradyonic transformations. Examples discussed include the electric dipole moment of a tachyonic current loop, constitutive equations, polarisation in tachyonic dielectric materials and the velocity of light in tachyonic dielectric media. This is followed by discussions of the collision energy loss for charged tachyons interacting with a material medium and a mathematical proof that tachyons cannot emit Cherenkov radiation when passing through a bradyonic ...

173

The number of cycles of specified normalized length in permutations  

CERN Document Server

We compute the limiting distribution, as n approaches infinity, of the number of cycles of length between gamma n and delta n in a permutation of [n] chosen uniformly at random, for constants gamma, delta such that 1/(k+1) <= gamma < delta <= 1/k for some integer k. This distribution is supported on {0, 1, ... k} and has 0th, 1st, ..., kth moments equal to those of a Poisson distribution with parameter log (delta/gamma). For more general choices of gamma, delta we show that such a limiting distribution exists, which can be given explicitly in terms of certain integrals over intersections of hypercubes with half-spaces; these integrals are analytically intractable but a recurrence specifying them can be given. The results herein provide a basis of comparison for similar statistics on restricted classes of permutations.

2009-01-01

174

The environmental Kuznets curve hypothesis for water pollution: Do regions matter?  

Energy Technology Data Exchange (ETDEWEB)

This study revisits the environmental Kuznets curve (EKC) hypothesis for water pollution by using a recent dynamic technique, which is the generalized method of moments (GMM) approach, for a board sample of 97 countries during the period 1980-2001. On a global scale, as we cannot obtain the EKC relationship between real income and biological oxygen demand (BOD) emissions, this paper further classifies these countries into four regional groups - Africa, Asia and Oceania, America, and Europe - to explore whether the different regions have different ECK relationships. The empirical results show evidence of the inverted U-shaped EKC relationships' existence in America and Europe, but not in Africa and Asia and Oceania. Thus, the regional difference of EKC for water pollution is supported. Furthermore, the estimated turning points are, approximately, US$13,956 and US$38,221 for America and Europe, respectively.

2010-01-15

175

The environmental Kuznets curve hypothesis for water pollution: Do regions matter?  

International Nuclear Information System (INIS)

This study revisits the environmental Kuznets curve (EKC) hypothesis for water pollution by using a recent dynamic technique, which is the generalized method of moments (GMM) approach, for a board sample of 97 countries during the period 1980-2001. On a global scale, as we cannot obtain the EKC relationship between real income and biological oxygen demand (BOD) emissions, this paper further classifies these countries into four regional groups - Africa, Asia and Oceania, America, and Europe - to explore whether the different regions have different ECK relationships. The empirical results show evidence of the inverted U-shaped EKC relationships' existence in America and Europe, but not in Africa and Asia and Oceania. Thus, the regional difference of EKC for water pollution is supported. Furthermore, the estimated turning points are, approximately, US$13,956 and US$38,221 for America and Europe, respectively.

2010-01-01

176

The environmental Kuznets curve hypothesis for water pollution. Do regions matter?  

Energy Technology Data Exchange (ETDEWEB)

This study revisits the environmental Kuznets curve (EKC) hypothesis for water pollution by using a recent dynamic technique, which is the generalized method of moments (GMM) approach, for a board sample of 97 countries during the period 1980-2001. On a global scale, as we cannot obtain the EKC relationship between real income and biological oxygen demand (BOD) emissions, this paper further classifies these countries into four regional groups - Africa, Asia and Oceania, America, and Europe - to explore whether the different regions have different ECK relationships. The empirical results show evidence of the inverted U-shaped EKC relationships' existence in America and Europe, but not in Africa and Asia and Oceania. Thus, the regional difference of EKC for water pollution is supported. Furthermore, the estimated turning points are, approximately, US$13,956 and US$38,221 for America and Europe, respectively. (author)

2010-01-15

177

Tachyons and experimental physics  

International Nuclear Information System (INIS)

An experimentalist looking for free tachyons is faced with the following two related problems: A) How does a tachyon interact with bradyonic matter. Is it an object more or less localized in space-time. B) How should a (bradyonic) detector for tachyons look. To answer B) you should necessarily know something about A). But a theory which provides sufficient information doesn't exist at the moment. Therefore it is necessary to make some simple assumption to tackle problem B). In the second part of this contribution two possibilities of tachyon detectors are proposed assuming that a free charged tachyon (if it exists) exhibits normal electromagnetic interaction with bradyonic matter. Another possibility to look for tachyons produced in high energy reactions of bradyons is the missing mass method using the fact that the four-momentum of a collection of particles can be spacelike if at least one tachyon is present. Such experiments have been undertaken with negative ...

178

Synthesis, Characterization and Biological Properties of Anions of Bivalent Transition Metal [Co(II) and Ni(II)] Complexes With Acylhydrazine Derived ONO Donor Schiff Bases.  

Science.gov (United States)

Some acylhydrazine derived ONO donor Schiff bases and their Co(II) and Ni(II) complexes have been prepared having the same metal ion (cation) but different anions. These synthesized metal(II) complexes have been characterized on the basis of their elemental analyses, magnetic moment, molar conductance, and IR and electronic spectral data. All of the Schiff base ligands function as tridentates and the deprotonated enolic form is preferred for coordination. In order to evaluate the effect of anions on the bactericidal activity, these synthesized complexes, in comparison to the uncomplexed Schiff bases have been screened against bacterial species., Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa and the results are reported. PMID:18475936

2000-01-01

179

Studies on the superconducting properties of A-15 type intermetallic compounds  

International Nuclear Information System (INIS)

The influence of 3d-transition metal impurities on the superconducting properties of the A-15 compounds V_3Si and V_3Ga have been investigated. In the case of V_3Si, the Fe impurities replacing V were found to have a local moment. A compensation effect was found in this case, resulting in a 20KOe increase in the upper critical field at dilute concentrations of Fe. It was demonstrated that long range order V_3Ga possessed higher transition temperature and upper critical field than found hitherto. Investigations on Nb_3Ge/sub 1-x/Ga/sub x/ films obtained by chemical vapor deposition has clearly shown the relation between the transition temperature and structural characteristics. The influence of generalized defects on the superconducting properties in A-15 type Nb_3X compounds has been discussed.

180

Studies on ball screw type damper with centrifugal brakes  

International Nuclear Information System (INIS)

The effects of vibration isolation of the new type of mechanical damper applied to a single-degree-of-freedom system and a simple beam are discussed numerically and experimentally. The damper is composed of a ball screw, a flywheel and centrifugal brakes, and possesses nonlinear characteristics. The Continuous System Simulation Language is used for the digital simulations of the nonlinear vibration systems. The results may be summarized as follows: (1) The damper is effective for suppressing the amplitude of the single-degree-of-freedom system as well as of the beam at the point of attachment of the damper, at the resonances. (2) The damper approaches a snubber for smaller values of lead L of the ball screw (or larger values of moment of inertia J of the flywheel), and acts like a damper whose damping force is proportional to the square of the velocity for larger values of L (or smaller values of J). (author).

1986-01-01

181

Structures, Vibrational And Electronic Properties Of (F2O)N (N=2-4) Clusters  

International Nuclear Information System (INIS)

Recently, molecular clusters are the subject of several experimental and computational studies by means of their bonding structures. We studied, first time, small difluorine monoxide clusters such as dimer (linear, cyclic, bifurcated), trimer and tetramer structures using B3LYP variant of density functional theory with cc-pVDZ basis set. On the basis of the optimized geometry, various energy properties such as binding energy, molecular orbital energies, two and three body interaction energies have been calculated. Additionally dipole moment, polarizability, anisotropic polarizability and hyper polarizability have been calculated and compared with monomer structure.

2008-08-25

182

Structural integrity of whipping pipes following postulated rupture - a contribution to strain levels acceptable under faulted conditions. Integritaetsverhalten von Rohrleitungen nach unterstelltem Rundabriss - ein Beitrag zur Dehnungsabsicherung bei Schadensfaellen  

Energy Technology Data Exchange (ETDEWEB)

By tests about pipe failure under extreme bending, moment at cross sections affected by circumferential cracks, admissible strains for securing the integrity in the area of a flow link are indicated. These are 7% for austenic and ferritic materials in the undisturbed cross section. From d/t-ratios of 20 onwards the strains are limited by pipe bulging on the pressure-load side. In this connection, circumferential flaws do not have any influence on the behaviour on the strained side, when their expansion does not exceed the investigated limitis of <60 circumferential expansion and crack depth of 0,3 t. (orig.)

1991-01-01

183

Solution of free vibration equations of semi-rigid connected Reddy?Bickford beams resting on elastic soil using the differential transform method  

British Library Electronic Table of Contents (United Kingdom)

The literature regarding the free vibration analysis of Bernoulli?Euler and Timoshenko beams under various supporting conditions is plenty, but the free vibration analysis of Reddy?Bickford beams with variable cross-section on elastic soil with/without axial force effect using the Differential Transform Method (DTM) has not been investigated by any of the studies in open literature so far. In this study, the free vibration analysis of axially loaded and semi-rigid connected Reddy?Bickford beam with variable cross-section on elastic soil is carried out by using DTM. The model has six degrees of freedom at the two ends, one transverse displacement and two rotations, and the end forces are a shear force and two end moments in this study. The governing differential equations of motion of the r...

2011-01-01

184

Resistivity, Hall effect, and magnetic susceptibility of UPd_2Si_2  

International Nuclear Information System (INIS)

The electrical resistivity, Hall effect, and magnetic susceptibility of single-crystal UPd_2Si_2 have been studied between 4.2 and 300 K. A large anisotropy was observed in both the magnetic and transport properties. There is a quadratic temperature dependence of the resistivity for a range of temperatures between 4.2 and 80 K. At higher temperatures, the resistivity indicates a Kondo-type behavior. The behavior of these quantities is accounted for by the magnetic phase transitions at 108 and 136 K reported from neutron-scattering studies. At high temperatures, the magnetic susceptibility of UPd_2Si_2 is Curie-Wiess-like along the c axis. The temperature dependence of the Hall coefficient above 108 K is accounted for by a theoretical model invoking skew scattering of conduction electrons by localized magnetic moments.

185

Resistivity, Hall effect, and magnetic susceptibility of UPd[sub 2]Si[sub 2  

Energy Technology Data Exchange (ETDEWEB)

The electrical resistivity, Hall effect, and magnetic susceptibility of single-crystal UPd[sub 2]Si[sub 2] have been studied between 4.2 and 300 K. A large anisotropy was observed in both the magnetic and transport properties. There is a quadratic temperature dependence of the resistivity for a range of temperatures between 4.2 and 80 K. At higher temperatures, the resistivity indicates a Kondo-type behavior. The behavior of these quantities is accounted for by the magnetic phase transitions at 108 and 136 K reported from neutron-scattering studies. At high temperatures, the magnetic susceptibility of UPd[sub 2]Si[sub 2] is Curie-Wiess-like along the [ital c] axis. The temperature dependence of the Hall coefficient above 108 K is accounted for by a theoretical model invoking skew scattering of conduction electrons by localized magnetic moments.

1993-12-15

186

Residual stresses in darrieus vertical axis wind turbine blades  

Energy Technology Data Exchange (ETDEWEB)

A numerical package called RESID has been assembled to calculate the residual stresses in VAWT blades induced during cold forming. Using a strength of materials - elementary beam theory approach, RESID models the material response with a bilinear stress-strain curve, and the cross-sectional geometry with an array of area increments. Through an iterative solution procedure residual stresses are predicted for a specified final radius of curvature or applied bending moment. RESID results are compared to theoretical solutions for simple geometries and with MARC Finite element results for VAWT blade geometries. Calculating residual stress levels, determining acceptable residual stress levels, and a method of reducing residual stresses are discussed. A complete listing and sample run are included in the appendicies.

1981-04-01

187

QCD corrections to top quark pair production in association with a photon at hadron colliders  

CERN Document Server

We compute QCD corrections to the production of a ttbar pair in association with a hard photon at the Tevatron and the LHC. This process allows a direct measurement of the top quark electromagnetic couplings that, at the moment, are only loosely constrained. We include top quark decays, treating them in the narrow width approximation, and retain spin correlations of final-state particles. Photon radiation off top quark decay products is included in our calculation and yields a significant contribution to the cross-section. We study next-to-leading order QCD corrections to the ppbar -> ttbar+gamma process at the Tevatron for the selection criteria used in a recent measurement by the CDF collaboration. We also discuss the impact of QCD corrections to the pp -> ttbar+gamma process on the measurement of the top quark electric charge at the 14 TeV LHC.

2011-01-01

188

Progress of negative-ion based NBI system for JT-60U  

Energy Technology Data Exchange (ETDEWEB)

The operation of the negative ion based NBI system for JT-60U has been progressed since 1996. Most of the efforts in the operation for increasing beam power and energy have been concentrated to get over the troubles, caused by surge energy at the moment of the accelerator break-down, in the ion sources and high voltage power supplies. The ion source for the N-NBI, so far, has accelerated negative ion beams of 14.3 A at 380 keV with deuterium and 18.5 A at 360 keV with hydrogen against the target of 22 A. The neutral beam power injected into JT-60U has already reached 5.2 MW at 350 keV for 0.7 sec with deuterium. (author)

1998-07-01

189

Prevalence and incidence of depressive and anxious symptoms in couples undergoing assisted reproductive treatment in an Italian infertility department  

British Library Electronic Table of Contents (United Kingdom)

Objective: We have conducted a longitudinal observational study in order to evaluate the prevalence and the incidence of depressive and anxious symptoms in women and men seeking infertility treatment and to analyze associated factors or risk factors for these kinds of disorders. Study design: A total of 1000 consecutive couples that visited our center for the first time were asked to join this study. Depressive and anxious symptoms were assessed with self-rating Zung Depression Scale (ZDS) and Zung Anxiety Scale (ZAS) questionnaires. A second assessment was planned at the time of b HCG dosage (or at the moment of cycle suspension). A standard questionnaire was used to investigate socio-demographic information and the psychological aspects of couples undergoing in vitro fertilization (IVF) ...

2011-01-01

190

Possible observation of the coexistence of superconductivity and long-range magnetic order in NdRh_4B_4  

International Nuclear Information System (INIS)

The ternary rare earth compound NdRh_4B_4 has been studied by means of critical field, low temperature heat capacity, and static magnetic susceptibility measurements. Features in the upper critical field and heat capacity data at 1.31 K and 0.89 K suggest the occurrence of long-range magnetic order in the superconducting state. The temperature dependence of the static magnetic susceptibility follows a Curie-Weiss law with an effective magnetic moment #mu#sub(eff) = 3.58 +- 0.05 #mu#sub(B) and a Curie-Weiss temperature thetasub(p) = -6.2 +- 1.0 K between 20 K and room temperature. However, magnetization vs. applied magnetic field isotherms suggest the development of a ferromagnetic component in the Nd"3"+ magnetization at low temperatures. (author).

1979-01-01

191

Polarized neutron diffraction study of CePd{sub 3}  

Energy Technology Data Exchange (ETDEWEB)

We have performed polarized neutron diffraction measurements on the intermediate valence compound CePd{sub 3} using the D3 spectrometer at the ILL. The results show that at low temperatures, 1.7 K, as well as at 100 K, the field-induced magnetic amplitudes measured in a field of 4.6 T could be interpreted in terms of two contributions: a 4f-type contribution with a Ce{sup 3+} form factor, and an extra delocalized contribution (relatively narrow in q-extent). In particular, we find that the values of the 4f moment deduced from the extrapolation of the neutron data to Q=0 are systematically lower than the values deduced from bulk magnetization measurements performed on the same sample. This difference can be ascribed to a possible positive polarization of the conduction band which is similar at both temperatures.

2004-07-15

192

Pipework design and operation  

Energy Technology Data Exchange (ETDEWEB)

This book presents the proceedings of a conference dedicated to the design and operation of pipework in all its aspects, involving both metallic and non-metallic materials. Topics considered include a study of single mitre pipe bends using the finite element method; tests to failure of GRP pipe bends under in-plane flexural loading; finite element stress analysis of an equal diameter branch pipe intersection subjected to internal pressure and in-plane moment loadings; finite element stress analysis of extruded outlet tee junctions; design of pipework on the British PWR; a review of advanced remanent life methods for pipes operating in the creep range; pipe whip analysis and design; damping values for piping systems; pipework snubbers based on electro-rheological fluids; and the seismic design of piping systems in the flexible range.

1985-01-01

193

Perturbation theory including topological degrees of freedom Yang-Mills theory in three Euclidean dimensions  

CERN Document Server

A method for systematically including topological degrees of freedom in perturbation theory is developed. This is not bound by the restrictions of semi-classical techniques. The Yang-Mills theory in three Euclidean dimensions is considered here. A well-defined separation of the topological and the ``spin wave'' degrees of freedom is obtained, motivated by a singular gauge. This has ``photons'' distorting the spherically symmetric magnetic fields of Dirac monopoles, and massless charged vector bosons ``W'' scattering off the latter. It is explicitly shown that the Dirac string does not contribute. The mode of the charged vector bosons with total angular momentum J=0 provides precisely the core to give a finite energy to the monopole. The radial equation for W is remarkably simplified and only two polarization states survive exactly for the anomalous magnetic moment required by the Yang-Mills interaction.

2003-01-01

194

Nuclear magnetic resonance on oriented "1"7"5Ta and "1"7"7Ta  

International Nuclear Information System (INIS)

"1"7"5Ta and "1"7"7Ta nuclei were oriented at low temperature as dilute impurities in Fe. The magnetic hyperfine splitting frequencies #nu#="+#mu#B sub(HF)/Ih"+ of the "1"7"5Ta and "1"7"7Ta ground states have been measured to be 320.45(11) and 317.552(55) MHz by using the technique of NMR-ON. Taking the known hyperfine field of "1"8"1Ta in Fe, the magneticmoments have been deduced: "+#mu#("1"7"5Ta, 7/2"+)"+=2.270(45) and "+#mu#("1"7"7Ta, 7/2"+)"+=2.250(45)#mu# sub(N). These values of the magnetic moments are discussed in the framework of the rotational model. (author).

195

Nonlinear dynamic analysis of high energy line pipe whip  

Energy Technology Data Exchange (ETDEWEB)

This paper describes a nonlinear dynamic analysis of TVA high energy line pipe whip tests using the ABAQUS-EPGEN code. The analysis considers the effects of large deformation and strain rate on resisting moment and energy absorption capability. The numerical results of impact forces, impact velocities, pipe strains, and reaction forces at pipe supports are compared to the TVA test data. The calculated pipe whip impact time and forces are also compared with those predicted using current industry practice. The calculated pipe support reaction forces are found to be in good agreement with the TVA test data except for some peak values at the very beginning of the pipe break. These peaks are believed to be due to stress wave propagation which cannot be addressed by the ABAQUS code. Both elbow crushing and strain rate have been approximately simulated. The effects are found to be important for pipe whip impact evaluation.

1984-02-01

196

Mother and infant coordinate heart rhythms through episodes of interaction synchrony  

British Library Electronic Table of Contents (United Kingdom)

Animal studies demonstrated the powerful impact of maternal-infant social contact on the infant's physiological systems, yet the online effects of social interactions on the human infant's physiology remain poorly understood. Mothers and their 3-month old infants were observed during face-to-face interactions while cardiac output was collected from mother and child. Micro-analysis of the partners' behavior marked episodes of gaze, affect, and vocal synchrony. Time-series analysis showed that mother and infant coordinate heart rhythms within lags of less than 1s. Bootstrapping analysis indicated that the concordance between maternal and infant biological rhythms increased significantly during episodes of affect and vocal synchrony compared to non-synchronous moments. Humans, like other mamm...

2011-01-01

197

Moessbauer investigation of the magnetic anisotropy and electronic structure of a metallic glass  

International Nuclear Information System (INIS)

The temperature dependence of the average magnetization direction in an Fe_8_0B_2_0 glassy alloy (METGLAS 2605) is investigated by Moessbauer spectroscopy. Moessbauer spectra were recorded between 77 K and 363 K using a conventional constant-acceleration Moessbauer spectrometer with 10 mCi "5"7Co in Pd source. The direction of the easy magnetization is found to be strongly terperature dependent and the out-of-plane component turned to be unusually large. Comparing the magnetic moments some similarities between the electronic structure of the glassy alloy and the Fe_2B and FeB intermetallic compounds are established and discussed. (Sz.N.Z.).

198

Modeling and forecasting short-term interest rates: The benefits of smooth regimes, macroeconomic variables, and bagging  

British Library Electronic Table of Contents (United Kingdom)

Abstract In this paper we propose a smooth transition tree model for both the conditional mean and variance of the short-term interest rate process. The estimation of such models is addressed and the asymptotic properties of the quasi-maximum likelihood estimator are derived. Model specification is also discussed. When the model is applied to the US short-term interest rate we find: (1) leading indicators for inflation and real activity are the most relevant predictors in characterizing the multiple regimes' structure; (2) the optimal model has three limiting regimes. Moreover, we provide empirical evidence of the power of the model in forecasting the first two conditional moments when it is used in connection with bootstrap aggregation (bagging). Copyright 2010 John Wiley & Sons, Ltd.

2011-01-01

199

Means and method of balancing multi-cylinder reciprocating machines  

Energy Technology Data Exchange (ETDEWEB)

A virtual balancing axis arrangement is described for multi-cylinder reciprocating piston machines for effectively balancing out imbalanced forces and minimizing residual imbalance moments acting on the crankshaft of such machines without requiring the use of additional parallel-arrayed balancing shafts or complex and expensive gear arrangements. The novel virtual balancing axis arrangement is capable of being designed into multi-cylinder reciprocating piston and crankshaft machines for substantially reducing vibrations induced during operation of such machines with only minimal number of additional component parts. Some of the required component parts may be available from parts already required for operation of auxiliary equipment, such as oil and water pumps used in certain types of reciprocating piston and crankshaft machine so that by appropriate location and dimensioning in accordance with the teachings of the invention, the virtual balancing axis arrangement ...

1985-01-01

200

Maximum entropy probability method applied to assess voltage sag frequency due to transmission line fault in the electric power system  

British Library Electronic Table of Contents (United Kingdom)

Abstract Voltage sag caused by faults on an electric power transmission line is one of the most intractable power quality issues for both utility companies and customers. The fault in power system randomly exists along transmission lines due to the combination of many uncertain factors. To predict and assess the annual expected sag frequency (ESF) deriving from the faults along lines, a stochastic based method that employs maximum entropy principle, namely the maximum entropy probability method (MEPM), has been introduced in this paper. Moreover, various types of faults have been considered systematically. With the fault line intervals and the sample moments taken into account, the discrete values of distribution probability of fault locations along the transmission lines have been estimat...

2010-01-01

201

Magnetic properties of some Au_3R compounds  

International Nuclear Information System (INIS)

The magnetization of a series of intermetallic compounds Au_3R, where R is Gd through Yb, was investigated at 2.5 to 300"0K in applied fields up to 26 kOe. All the compounds studied exhibited the orthorhombic TiCu_3--Do/sub a/ type structure. For high temperatures, the temperature dependence of the inverse susceptibility followed a Curie--Weiss law, yielding effective paramagnetic moments in good agreement with the values calculated for free tripositive rare earth ions. At low temperatures, deviations from Curie--Weiss behavior were observed in all cases. These deviations are ascribed to the influence of crystal-field and exchange interactions. (auth).

1974-12-03

202

Magnetic behavior and crystal field of Pr"3"+ in praseodymium selenate octahydrate  

International Nuclear Information System (INIS)

Measurements are made on the principal magnetic susceptibilities and anisotropies of praseodymium selenate octahydrate single crystals in the temperature range 90 to 300 K. Although the effective magnetic moment is close to the free ion value, the anisotropy is quite high at room temperature. A least sequares fit of the Curie-Weiss law to the observed average susceptibility yields -36.5 K as the paramagnetic Curie temperature. An analysis of the results with a crystal field (CF) of D_4 symmetry, explains the observed results quite well. The CF and the spin-orbit interaction matrix is block diagonalized in the complete 33 dimensional basis of the "3H term in order to obtain the Stark energies and their eigenstates. Intermediate coupling effects are also considered. The ground state being a singlet, the g-factors are absent. Some predictions on the electronic heat capacity and the electronic quadrupole splitting are made in the light of the proposed CF. (author).

1988-09-01

203

Machine condition monitoring - the way ahead  

Energy Technology Data Exchange (ETDEWEB)

During the last fifteen years a variety of instruments and transducers, such as voltage plugs, power transducers, flow and pressure transducers, recorders and tensometers, have been developed for underground use in measuring the performance and technical parameters of prototype machines. The equipment, until recently, has been in a portable form and was found useful by the industry generally, in fault finding and trouble-shooting exercises and in commissioning procedures performed by small teams on a call-out basis. Over the last five years the test equipment has been adapted and the techniques modified to suit individual colliery-based operations with more permanent machine mounted and built-in transducers. At the moment these techniques operate within the framework of a statutory planned preventive maintenance scheme for each mine. This paper discusses the merits of changing from preventive maintenance to condition-based maintenance and the practical steps being ...

1984-11-01

204

Innovative wind turbines. Circulation controlled vertical axis wind turbine. Progress report, March 1-December 31, 1976  

Science.gov (United States)

Theoretical and experimental research efforts in evaluating an innovative concept for vertical axis wind turbines (VAWT) are described. The concept is that of using straight blades composed of circulation controlled airfoil sections. The theoretical analysis has been developed to determine the unsteady lift and moment characteristics of multiple-blade cross-flow wind turbines. To determine the drag data needed as input to the theoretical analysis, an outdoor test model VAWT has been constructed; design details, instrumentation, and calibration results are reported. Initial testing is with fixed pitch blades having cross-sections of conventional symmetrical airfoils. Costs of building the test model are included, as well as estimates for blades constructed with composite materials. These costs are compared with those of other types of wind turbines.

1978-10-01

205

Influence of performance characteristic of a gaseous fuel supply system on hydrocarbon emissions of a dual-fuel engine  

Energy Technology Data Exchange (ETDEWEB)

The performance of the gaseous fuel supply and its influence on hydrocarbon (HC) emissions of dual-fuel engines have been investigated. A new design of manifold respirators with mixers is also presented in the paper. The design of the gaseous fuel supply system has a great influence on HC emissions in the dual-fuel engine at light load. The problem of scavenging is discussed and solved by using the manifold respirators in the dual-fuel engine. It performs the function of retarding the gaseous fuel entry timing from the moment of intake valve opening, and its delaying effects have been measured and tested. Experimental results show that the manifold respirator gives the best performance in reducing HC emissions compared with a common pipe mixer and a respirator with bo miser. In addition, the mixing effects are sensitive to the mixer configuration. (Author)

2000-11-01

206

IBM-2 calculation of band mixing in "1"3"2Ba  

International Nuclear Information System (INIS)

The band crossing in "1"3"2Ba has been investigated by using the interacting boson model. A broken neutron pair has been coupled to a collective boson core. The boson-fermion interaction hamiltonian contains terms which can transform a boson into a pair of quasiparticles and vice versa. The parameters were partly determined by fitting the collective states of "1"3"2","1"3"4Ba and the yrast states of "1"3"1Ba. The energy backbending has been satisfactorily reproduced. Good agreement of the electromagnetic moments has been reached. The structure of the wave functions has been discussed. (author)

1999-12-04

207

Heat capacity and magnetic ordering of two cerium sulfides, CeS/sub 1. 393/ and CeS/sub 1. 457/  

Energy Technology Data Exchange (ETDEWEB)

Heat-capacity (0.5--20 K) and magnetic-susceptibility (4--300 K) measurements have been made on two cerium sulfide samples having compositions as CeS/sub 1.393/ and CeS/sub 1.457/. These materials follow the Curie-Weiss law above 100 K, and become ferromagnetically ordered near 6 and 3 K, respectively. Shift of the ordering to higher temperatures under applied magnetic fields is also observed in CeS/sub 1.457/. The estimated effective magnetic moment and entropy associated with the ordering are consistent with the paramagnetic nature of Ce/sup 3 +/ (4f/sup 1/) in a crystalline environment.

1982-08-01

208

Estimating hip fracture risk from digital x-ray image data  

International Nuclear Information System (INIS)

The authors propose a method for determining the risk of femoral neck fracture in osteoporotic patients that is not based on densitometric techniques. The method is based on a structural analysis performed by a computer on data taken from a single digital anteroposterior projection of the hip. From the image, the effective cross-sectional area and cross-sectional moment of inertia are computed from attenuation principles. Together with other geometric measurements, these data are used in an engineering analysis to compute the yield strength of the proximal femur, under stress applied through the acetabulum in a one-legged stance. An index of fracture risk based on the ratio of estimated yield strength to body weight is proposed. Ultimately it is expected that this work will allow the clinician to estimate hip fracture risk in osteoporotic patient using widely available existing technology, a goal which has eluded bone density-based methods.

209

Electronic structure of p-type (Ga,Fe)N diluted magnetic semiconductors  

Energy Technology Data Exchange (ETDEWEB)

By ab-initio calculation we show that the (Ga,Fe)N ground state may be changed from anti-ferromagnetic to ferromagnetic by acceptor defect like Ga vacancies. The electronic structures are calculated by using the Korringa-Kohn-Rostoker (KKR) method combined with coherent potential approximation (CPA). We show that we can increase the magnetic moment of Fe in p-type GaN by oxygen co-doping. Mechanism of exchange interactions between magnetic ions in p-type (Ga,Fe)N is also studied. The effect of external magnetic field on the electronic structure of (Ga, Fe)N and p-type (Ga, Fe)N is investigated.

2009-08-15

210

Effect of Kerr nonlinearity on an Airy beam  

International Nuclear Information System (INIS)

The effect of Kerr nonlinearity on an Airy beam is investigated by using the nonlinear Schroedinger equation. Based on the moments method, the evolution of the Airy beam width in the rms sense is analytically described. Numerical simulations indicate that the central parts of the major lobe of the Airy beam initially give rise to radial compression during propagation in a focusing medium, even though the rms beam width broadens. The partial collapse of the center parts of the major lobe of the beam appear below the threshold for a global collapse. The evolutions of the field distributions of the Airy beams are different during propagation in different Kerr media while the beams still travel along the parabolic trajectory just as the beam propagates in free space.

2010-10-01

211

Dielectric studies of hydrogen bonded ternary systems: Acetonitrile+alcohols+benzene  

British Library Electronic Table of Contents (United Kingdom)

Any molecule which has a hydrogen atom attached directly to oxygen or nitrogen is capable of hydrogen bonding. The molecular complexes formed by hydrogen have particularly attracted considerable attention to understand the nature of the bond. The hydrogen bonded complexes formed by acetonitrile with certain alcohols such as tertiary butyl alcohol, isoamyl alcohol, cyclohexyl alcohol, hexyl alcohol and diethylene glycol in benzene were studied. The dipole moments of 1:1 complexes of the above said systems were determined at 308K. The dipolar increments for these systems were computed from the bond angle data available from molecular orbital studies. All these studied systems show that polarization interaction dominates in all the complexes.

2010-01-01

212

Crystal structure and magnetic properties of R/sub 6/Cu/sub 8/Sn/sub 8/ compounds (R=Gd, Tb, Dy, Ho, Er, Tm)  

Energy Technology Data Exchange (ETDEWEB)

The crystal structure of R/sub 6/Cu/sub 8/Sn/sub 8/ compounds (R=Gd, Tb, Dy, Ho, Er, Tm) is determined and their magnetic susceptibility is measured in the temperature range 78-293 K. The structure of the compounds is isotypical with the Gd/sub 6/Cu/sub 8/Ge/sub 8/ type (space group Immm, Z=1). The magnetic susceptibility of the R/sub 6/Cu/sub 8/Sn/sub 8/ compounds is described by the Curie-Weiss law. Effective magnetic moments of R/sub 6/Cu/sub 8/Sn/sub 8/ compounds (R=Gd, Tb, Dy, Ho, Er, Tm) are in good agreement with theoretical values for free R/sup 3 +/ ions.

1984-09-01

213

Concerning the statistics of cosmic magnetism  

CERN Document Server

Magnetic fields appear to be a generic feature of the early universe and are a natural source of secondary CMB non-Gaussianity. In recent years the statistical nature of the stresses of a primordial magnetic field has been well studied. In this paper we confirm and extend these studies at one- and two-point level, and present analytical results for a wide range of power-law spectra. We also consider two non-power law cases of interest: a blue spectrum with an extended damping tail on small scales, which could be generated by the non-linear mixing of density and vorticity; and a red spectrum with a damping tail on large scales. We then briefly consider the CMB impacts that result from such fields. While this paper focuses on the one- and two-point moments, the techniques we employ are designed to ease the analysis of the full bispectra induced by primordial magnetic fields.

2010-01-01

214

Computational study of non-stationary cluster size distribution and rate of nucleation in case of pre-existing clusters  

International Nuclear Information System (INIS)

The dynamics of a cluster-type system formed by constant total number of molecules, M, is studied when clusters change their sizes by nearest-size transitions (the Szilard model) with time-dependent boundary conditions and non-zero initial cluster size distribution. We compare these results to those reported previously, when non-stationary cluster size distribution was considered under the condition that only monomers are present in the system at the initial moment t=0, and describe the effect of arbitrary pre-existing clusters on the time evolution of the interacting clusters with different sizes, n. The average group size problem is also solved, and the process of relaxation in the system is studied. authors)

215

Chromatographic evaluation of microbial activity in biological activated carbon bed; Kuromatoho ni yoru seibutsu kasseitanso ni okeru biseibutsu kassei no hyoka  

Energy Technology Data Exchange (ETDEWEB)

The moment analysis of pulse responses was applied to a biological activated carbon (BAC) bed to evaluate the microbial activity. Glucose and activated carbon fiber (ACF) were employed in experiments as a model tracer and an activated carbon respectively. No significant difference in biodegradation rates of glucose by microorganisms attached on different solid supports such as activated carbon inactivated carbon and glass fibers was observed. However, higher microbial activity was obtained from microorganisms supported on the ACF in terms of the apparent degradation of total organic including metabolic byproducts by microorganisms, since part of the metabolic byproducts was irreversibly deposited onto the ACF. 11 refs., 6 figs.

1996-07-10

216

Augmented-plane-wave calculations on small molecules  

International Nuclear Information System (INIS)

We have performed ab initio calculations on a wide range of small molecules, demonstrating the accuracy and flexibility of an alternative method for calculating the electronic structure of molecules, solids, and surfaces. It is based on the local-density approximation (LDA) for exchange and correlation and the nonlinear augmented-plane-wave method. Very accurate atomic forces are obtained directly. This allows for implementation of Car-Parrinello-like techniques to determine simultaneously the self-consistent electron wave functions and the equilibrium atomic positions within an iterative scheme. We find excellent agreement with the best existing LDA-based calculations and remarkable agreement with experiment for the equilibrium geometries, vibrational frequencies, and dipole moments of a wide variety of molecules, including strongly bound homopolar and polar molecules, hydrogen-bound and electron-deficient molecules, and weakly bound alkali and noble-metal dimers, ...

217

Assuring both quality and creativity in basic research  

Energy Technology Data Exchange (ETDEWEB)

How does one assure that both quality and creativity are obtained in basic research environments QA theoreticians have attempted to develop workable definitions of quality, but in more reflective moments, these definitions often fail to capture the deeper essence of the idea of quality.'' This paper asserts that creativity (as a product of the human mind) is a concrete interface between perfunctory definitions of quality (conformance to specifications) and more philosophical speculations about the nature of quality- related ultimates'' like elegance or beauty. In addition, we describe the distinction between creative ideas and creative acts and highlight one of the major inhibitors of creativity, fear. Finally we show that highly creative people often have an irreverent attitude toward boundaries and established authority, and discuss how one can allow for this when designing a QA program in a basic research environment.

1990-04-12

218

An institutional architecture for meta-risk regulation in Irish banking: Lessons from Anglo Irish Bank’s Minsky moment  

British Library Electronic Table of Contents (United Kingdom)

The article maps the risk management failures within Anglo Irish Bank, showing that, when banks are systemic in nature, poor internal corporate governance within a Minsky credit cycle can lead to destabilising macroeconomic conditions, which may prolong the effects of a credit-induced downturn. The article highlights a failure of management at Anglo Irish Bank to establish and measure firm-level risks and develop appropriate internal controls to support a culture of prudent credit management. We propose the adoption of a novel supervisory architecture based on the meta-risk regulatory philosophy, which is designed to strengthen risk management practices at banks.

2011-01-01

219

Adsorption and Dissociation of Molecular Hydrogen on the (0001) Surface of DHCP Americium  

Science.gov (United States)

Hydrogen molecule adsorption on the (0001) surface of double hexagonal closed packed americium has been studied in detail within the framework of density functional theory. Weak molecular hydrogen adsorptions were observed. The most stable configuration corresponded to a Hor2 approach molecular adsorption at the one-fold top site where the molecule's approach is perpendicular to a lattice vector. Adsorption energies and adsorption geometries for different adsorption sites will be discussed. The change in work functions, magnetic moments, partial charges inside muffin-tins, difference charge density distributions and density of states for the bare Am slab and the Am slab after adsorption of the hydrogen molecule will be discussed. Reaction barrier for the dissociation of hydrogen molecule will be presented. The implications of adsorption on Am 5f electron localization-delocalization will be summarized.

2009-03-01

220

A polarized neutron reflectometry study of the spin glass freezing in a 29 nm thick AuFe film  

Energy Technology Data Exchange (ETDEWEB)

We performed polarized neutron reflectometry (PNR) experiments on a 29 nm thick Au{sub 93}Fe{sub 7} film in a temperature range from 295 K down to 2 K in a vertical magnetic field up to 6 T. These high-field experiments were performed on the C5 spectrometer in Chalk River, Canada, using a split-pair cryomagnet. The magnetization as determined by PNR can be described with a Brillouin function from 295 K down to 50 K assuming the magnetic moment of isolated Fe atoms, i.e. 4{mu}{sub B} per Fe atom. Below 50 K the onset of the spin-glass freezing is observed as a strong deviation from this Brillouin type behavior of isolated atoms.

2007-07-15

221

A microscopic model of electronic field noise heating in ion traps  

CERN Document Server

Motional heating of ions in micro-fabricated traps is a challenge hindering experimental realization of large-scale quantum processing devices. Recently a series of measurements of the heating rates in surface-electrode ion traps characterized their frequency, distance, and temperature dependencies, but our understanding of the microscopic origin of this noise is still vague. In this work we develop a theoretical model for the electric field noise which is associated with a random distribution of adsorbed atoms on the trap electrode surface. By using first principle calculations of the fluctuating dipole moments of the adsorbed atoms we evaluate the distance, frequency and temperature dependence of the resulting electric field fluctuation spectrum.Our theory calculates the noise spectrum beyond the standard scenario of two-level fluctuators, by incorporating all the relevant vibrational states. The $1/f$ noise is shown to commence at roughly the frequency of the ...

2011-01-01

222

A method for lowering into water a support block for an offshore drilling rig  

Energy Technology Data Exchange (ETDEWEB)

A procedure for lowering an offshore rig support block into water, one with water displacement elements, including transfering a structure ready for installation from construction supports onto the grillage that has been set up on the slide, and then lowering the structure together with the grillage into the water. With the goal of dereasing the volume of hydrotechnical operations, the slides have been extended only to the waterline, and the water-displacing elements of the support block are mounted or the structure in a manner whereby the following conditions are fulfilled: Msigmaless than or equal toM /SUB wi/ sigma-W/Lless than or equal toq where Msigma, M /SUB w/ - are the mass moments of the support block and bouyancy forces correspond to the threshhold; sigma and W - the weight force and bouyancy; L - the support length of the block on the grillage; q - the allowable linear load for the support block structure.

1981-10-09

223

A density Functional Calculations on The Geometrical Electronic and Nonlinear Optical Properties of Thienyl Oxazoles and Thienyl Isoxazoles  

International Nuclear Information System (INIS)

Thienyl oxazoles and thienyl isoxazoles, are composite molecules having two subsystems thiophene and oxazole molecules connected together by a single bond that they have 13 isomers. They are potential candidates for many kinds of applications such as OLED and nonlinear optical materials. Initially equilibrium geometries of title compounds have been obtained without any restriction using density functional theory with 6-311++g(2d,p) basis set. We obtained structural parameters, dipole moment and electronic energy. At the second stage, we have calculated some electronic and nonlinear optical properties such as HOMO and LUMO energies, polarizability, anisotropic polarizability and hyper polarizability using same level of theory.

2008-08-25

224

A computational study of aluminum phosphide nanotubes  

British Library Electronic Table of Contents (United Kingdom)

Abstract Electronic structures of two representative zigzag and armchair models of aluminum phosphide nanotube (AlPNT) were investigated by density functional theory calculations. The structures were optimized and the bond lengths, tip diameters, band gaps, and dipole moments were calculated. Moreover, the quadrupole coupling constants (CQ) were calculated for the Al-27 atoms of the optimized structures. The same values of AlP bond lengths were calculated for both models. The larger value of band gap of armchair model than the zigzag model indicated the stronger dielectric property for the former model. The values of CQ(27Al) were the largest for the Al atoms placed at the tips of both zigzag and armchair AlPNT than other Al atoms, which could reveal dominant role of the Al atoms placed at...

2011-01-01

225

The role of the negative selection activities in securing the competence of an organization belonging to SEN units  

International Nuclear Information System (INIS)

The transformation and the accommodation of National Power System (SEN) units to a new management system, own to a decentralized economy and having financial support from both native capital and foreign capital, in uncertain proportion at the moment and being in a continuous adjustment determined by the reasons and the motivations first of all political, generated conceptual changes in the so-called modern management theory. The accommodation of this theory to the concrete situation from SEN units imposed the concept of negative selection. It is a concept which represents author's desire to be created as an original contribution to the contemporary management theory. Unlike the selection at the hiring (or positive selection), the negative selection is achieved on personal already employed, in the conditions of activities of a decreased number of personnel and also of a redistribution of personnel on the other side. The negative selection, much more than the ...

2008-05-28

226

The accurate magnetic structure of CeAl{sub 2} at various temperatures in the ordered state  

Energy Technology Data Exchange (ETDEWEB)

The magnetic structure of the cubic compound CeAl{sub 2} is incommensurate and double-k. The moments on the two Ce sites describe two elliptical helices of opposed chiralities and lie in the (11-bar0) plane, with their Fourier components m{sup k} close to the [111] direction. Recent symmetry considerations, including for the first time the inversion center of the crystal, have reduced the number of parameters of this structure and have underlined the existence of a phase difference between the projections m{sub x}{sup k}, m{sub y}{sup k} and m{sub z}{sup k} of m{sup k}. Up to now, although many neutron investigations have been carried out on CeAl{sub 2} single crystals, no set of magnetic intensities was available which was large and good enough to check whether this phase difference exists or not. We have measured such a set of data, taking great care of the instrumental resolution in order to avoid unwanted contributions to the intensities from other domains. As ...

2008-04-02

227

The accurate magnetic structure of CeAl_2 at various temperatures in the ordered state  

International Nuclear Information System (INIS)

The magnetic structure of the cubic compound CeAl_2 is incommensurate and double-k. The moments on the two Ce sites describe two elliptical helices of opposed chiralities and lie in the (11-bar0) plane, with their Fourier components m"k close to the [111] direction. Recent symmetry considerations, including for the first time the inversion center of the crystal, have reduced the number of parameters of this structure and have underlined the existence of a phase difference between the projections m_x"k, m_y"k and m_z"k of m"k. Up to now, although many neutron investigations have been carried out on CeAl_2 single crystals, no set of magnetic intensities was available which was large and good enough to check whether this phase difference exists or not. We have measured such a set of data, taking great care of the instrumental resolution in order to avoid unwanted contributions to the intensities from other domains. As the magnetic form factor of the #GAMMA#_7 ground ...

2008-04-02

228

Rapid yield learning through optical defect and electrical test analysis  

Energy Technology Data Exchange (ETDEWEB)

As semiconductor device density and wafer area continue to increase, the volume of in-line and off-line data required to diagnose yield-limiting conditions is growing exponentially. To manage this data in the future, analysis tools will be required that can automatically reduce this data to useful information, e.g., by assisting the engineer in rapid root-cause diagnosis of defect generating mechanisms. In this paper, the authors describe a technology known as Spatial Signature Analysis (SSA) and its application to both optically-detected defect data as well as electrical test (e-test) bin data. The results of a validation study are summarized that demonstrate the effectiveness of the SSA approach on optical defect wafermaps through field-testing at three semiconductor manufacturing sites on ASIC, DRAM and SRAM products. This method has been extended to analyze and interpret electrical test data and to provide a pathway for correlation of this data with in-line optical measurements. ...

1998-02-01

229

Noncollinear magnetism in surfaces and interfaces of transition metals  

Energy Technology Data Exchange (ETDEWEB)

Noncollinear (NC) magnetism is common in nature, especially when there exist geometrical frustration and chemical imparity in the system. In this work we studied the NC magnetism and the response to external magnetic fields in surfaces and interfaces of transition metals by using an semi-empirical tight-binding (TB) method that parameterized to the ab initio TB-LMTO calculations. We implemented this method to study two systems. The first one is the system of 6 Mn monolayers on Fe(001) substrate. Due to the complex structure and magnetic properties of Mn, we found 23 collinear magnetic configurations but only one NC configuration. The collinear ground state has a layered antiferromagnetic (AFM) coupling which agrees with previous experiments and calculations. In the NC configuration the local AFM coupling in the Mn layers is preserved, but the surface is 90 degree coupled to the substrate. Similar to the experiment in CdCr{sub 2}O{sub 4}, we obtained a collinear plateau in the NC ...

2009-09-15

230

Magnetocaloric effect of Gd{sub 4}(Bi{sub x}Sb{sub 1{minus}x}){sub 3} alloy series  

Energy Technology Data Exchange (ETDEWEB)

Alloys from the Gd{sub 4}(Bi{sub x}Sb{sub 1{minus}x}){sub 3} series were prepared by melting a stoichiometric amounts of pure metals in an induction furnace. The crystal structure is of the anti-Th{sub 3}P{sub 4} type (space group I{bar 4}3d) for all the compounds tested. The linear increase of the lattice parameters with Bi concentration is attributed to the larger atomic radius of Bi than that of Sb. Magnetic measurements show that the alloys order ferromagnetically from 266K to 330K, with the ordering temperature increasing with decreasing Bi concentration. The alloys are soft ferromagnets below their Curie temperatures, and follow the Curie-Weiss law above their ordering temperatures. The paramagnetic effective magnetic moments are low compared to the theoretical value for a free Gd{sup 3+}, while the ordered magnetic moments are close to the theoretical value for Gd. The alloys exhibit a moderate magnetocaloric effect (MCE) whose maxima ...

1999-12-01

231

Magnetization and magnetic susceptibilities of GdH_3, HoH_3, ErH_3 and YbH_3  

International Nuclear Information System (INIS)

The magnetic susceptibility of powdered samples of HoH_3, ErH_3, GdH_3 and YbH_3 have been measured in the temperature range from 4.2 to 1.2 K. Two broad, local maxima are observed in the variation of chi versus T for GdH_3, with maxima in (delta chi/delta T) versus T at 1.8 K and 3.3 K. The inverse susceptibilities for HoH_3 and ErH_3 both obey a Curie--Weiss law over a limited range (4.2 to 2.6 K and 4.2 to 2 K, respectively) with values for the Weiss constant of -4.25 K and -1.11 K, and effective moments of 8.6 and 7.7 Bohr magnetons, respectively. The susceptibility of YbH_3 is independent of temperature over the range investigated. High-field magnetization measurements yield extrapolated saturation moments of 7.0 +- 0.25 Bohr magnetons/ion for GdH_3, 6.1 +- 0.2 Bohr magnetons/ion for HoH_3 and 3.74 +- 0.11 Bohr magnetons/ion for ErH_3. In addition, ErH_3 exhibits a van Vleck paramagnetism in the high-field region.

1976-03-29

232

Magnetic properties of Ni/sub 100-2x/Mn/sub x/Sb/sub x/-alloys (5less than or equal toxless than or equal to50) - solid and liquid state  

Energy Technology Data Exchange (ETDEWEB)

Magnetothermal measurements up to 1600 K have been made on alloys in the ternary Ni-Mn-Sb system with a constant ratio Mn/Sb=1/1, to which belong the two ferromagnetic Heusler phases Ni/sub 2/MnSb with L2/sub 1/ structure and NiMnSb with C1/sub b/ structure. The susceptibility-temperature curves show the constitution of the vertical section. At high temperatures the susceptibilities obey a Curie-Weiss law. In the solid state the effective magneton number decreases with increasing Mn concentration from 4.9 (Ni/sub 2/MnSb) to 3.8 (NiMnSb). Simultaneously, on the transition from Ni/sub 2/MnSb to NiMnSb there is a strong increase of the susceptibility and of the Curie temperature from 292 to 686 K. In the heterogeneous range between 10 and 20 at.% Mn another phase part appears which is ferromagnetic at room temperature. By a heat treatment it undergoes a distinct development. In the liquid phase, the alloys can be characterized by an extended Curie-Weiss law. Between 20 and 50 at.% Mn a ...

1989-02-01

233

Magnetic properties and low temperature X-ray studies of the weak ferromagnetic monoclinic and trigonal chromium tellurides Cr_5Te_8  

International Nuclear Information System (INIS)

Monoclinic and trigonal Cr_5Te_8 show a transition into the ferromagnetic state with a Curie temperature T_c, which sensitively depends on the actual composition. Monoclinic samples exhibit a lower T_c despite their higher Cr content. This observation is explained on the basis of less effective ferromagnetic superexchange in the monoclinic compounds and the larger number of Cr atoms being antiferromagnetically coupled. Magnetization experiments performed at 5 K demonstrate that the compounds saturate already at rather low magnetic fields. In addition, small values are estimated for the coercitive field H_c as well as for the remanence magnetization both being typical for weak ferromagnetic materials. The values for the saturation magnetization amount to about 72% and 65% for monoclinic and trigonal Cr_5Te_8, respectively. These low values can partially be explained on the basis of antiferromagnetically coupled Cr(III) d"3 centers. An additional spin canting is assumed to fully account ...

2004-03-01

234

Magnetic moment of the three-quasiparticle state in /sup 177/Ta  

Energy Technology Data Exchange (ETDEWEB)

An experimental investigation was made of the ..gamma..-transitions feeding or de-exciting the 1355 keV isomeric state in /sup 177/Ta. The E2/M1 mixing ratios for the 311 keV interband transition from the isomer and for the 271 keV and the 295 keV intraband transitions within the rotational band on the isomer were determined to be delta = 0.29sup(+0.11)sub(-0.06), 0.25sup(+0.05)sub(-0.03) and 0.30sup(+0.06)sub(-0.08), respectively, employing combined measurements of the linear polarization and angular distribution of the ..gamma..-ray with the aid of conversion electron measurements. Spin and parity assignments of the isomer were confirmed to be 21/2/sup -/. The half-life of the isomer was remeasured to be Tsub(1/2) = 5.0 +- 0.2 ..mu..s and the magnetic moment was found to be ..mu.. = 0.080 +- 0.014 ..mu..sub(N). The gsub(K) and gsub(R) factors for the band on the isomer were deduced separately to be gsub(K=21/2/sup -/) = 0.062sup(+0.011)sub(-0.008) and gsub(R) = ...

1982-06-07

235

Magnetic moment of the three-quasiparticle state in "1"7"7Ta  

International Nuclear Information System (INIS)

An experimental investigation was made of the #gamma#-transitions feeding or de-exciting the 1355 keV isomeric state in "1"7"7Ta. The E2/M1 mixing ratios for the 311 keV interband transition from the isomer and for the 271 keV and the 295 keV intraband transitions within the rotational band on the isomer were determined to be delta = 0.29sup(+0.11)sub(-0.06), 0.25sup(+0.05)sub(-0.03) and 0.30sup(+0.06)sub(-0.08), respectively, employing combined measurements of the linear polarization and angular distribution of the #gamma#-ray with the aid of conversion electron measurements. Spin and parity assignments of the isomer were confirmed to be 21/2"-. The half-life of the isomer was remeasured to be Tsub(1/2) = 5.0 +- 0.2 #mu#s and the magnetic moment was found to be #mu# = 0.080 +- 0.014 #mu#sub(N). The gsub(K) and gsub(R) factors for the band on the isomer were deduced separately to be gsub(K=21/2"-) = 0.062sup(+0.011)sub(-0.008) and gsub(R) = ...

236

Low-temperature behavior of two ternary lanthanide nickel carbides: Superconducting LaNiC_2 and magnetic CeNiC_2  

International Nuclear Information System (INIS)

A study of the magnetic properties and the heat capacity as functions of temperature and magnetic field of two ternary carbides RNiC_2, where R=La and Ce, confirms that LaNiC_2 becomes superconducting at T_c=2.7thinspK, and that CeNiC_2 orders antiferromagnetically below 18thinspK. LaNiC_2 is a conventional superconductor with a critical field of 900 Oe at T=2thinspK. CeNiC_2 obeys the Curie-Weiss law between 50 and 300thinspK showing the nearly full Ce"3"+ magnetic moment, p_e_f_f=2.47(1)#mu#_B, and has a negative paramagnetic Weiss temperature #THETA#_p=-18.3(8)thinspK. A low net magnetic moment in the ordered state, which is far from saturation in a magnetic field of 5thinspT, is consistent with an antiferromagnetic ground state. Below 20thinspK CeNiC_2 shows multiple-step magnetic transitions at 18, 10, and 2.4thinspK. Both LaNiC_2 (in the normal state) and CeNiC_2 have the same electronic heat capacity, #gamma#=6.5(2)thinspmJ/molthinspK"2, ...

1998-07-01

237

Visualization of direct contact heat transfer between water and molten alloy  

Energy Technology Data Exchange (ETDEWEB)

We have been developing an innovative Steam Generator concept of Fast Breeder Reactors by using liquid-liquid direct contact heat transfer. In this concept, the SG shell is filled with a molten alloys, which is heated by primary sodium. Water is fed into the high temperature molten alloy, and evaporates by direct contact heating. In order to obtain the fundamental information to discuss the heat transfer mechanisms of the direct contact between the water and the alloy, this phenomenon was visualized by real-time neutron radiography. JRR-3M real-time thermal neutron radiography in Japan Atomic Energy Research Institute was used. Followings are main results. (1) The vigorous evaporation occurs in the molten alloy. This phenomena is different from the known phenomenon such as the evaporation of refrigerant R-113 in the water. (2) The evaporation in the bubble has finished in a moment due to high heat transfer performance between the liquid and molten alloy. (3) It is ...

1996-06-01

238

Treatment of produced water using hydrocyclones; Tratamento de agua produzida usando hidrociclone  

Energy Technology Data Exchange (ETDEWEB)

Beyond a great number of applications in mineral process, the hydrocyclone separation has been used recently in an increasing number of fields, such as: environmental engineering, petrochemical engineering, food engineering, electrochemical engineering, pulp bioengineering, processes and paper industries, among others. Nowadays, the produced water is treated and then reinjected in the surface and also in return to the formation. In the offshore platforms, the produced water can be directly discarded in the ocean, since the dispersed phase concentration (oil) is according to Brazilian regulating agency limits. The basic principle used in hydrocyclone separation is the centrifugal sedimentation machine: the suspended particles are submitted to centrifugal acceleration, which separates them from the fluid. The basic geometry of a hydrocyclone consists of four parts: a cylindrical section for feeding, a conical section for swirling, an overflow and an under flow. The project depends on the ...

2008-07-01

239

Theoretical study of indoline dyes for dye-sensitized solar cells  

International Nuclear Information System (INIS)

Indoline dye sensitizers were designed and studied theoretically to increase molar extinction coefficients in the visible to near infrared region for solar-cell devices. To gain insight into dye sensitizers' structural, electronic, and optical properties, DFT/TDDFT calculations were performed on a series of dye sensitizers derived from the D149. The good agreement between the experimental and TDDFT calculated absorption spectra of the D149 sensitizer allowed us to provide a detailed assessment of the main spectral features of a series of dye sensitizers. Increase in the conjugation length resulted in a more red-shifted spectral response and less positive oxidation potential than that of the D149. The dye with the dimethylfluorene group showed stronger absorption bands due to a large dipole moment. The calculated dipoles for the dye series correlate well with the observed strong absorption bands of the electronic spectra. These results provided useful clues for the ...

2010-09-01

240

The role of 5-quark components on the nucleon form factors  

Energy Technology Data Exchange (ETDEWEB)

The covariant quark model is shown to allow a phenomenological description of the neutron electric form factor, G{sub E}{sup n}(Q{sup 2}), in the impulse approximation, provided that the wave function contains minor ({approx}3%) admixtures of the lowest energy sea-quark configurations. While that form factor is not very sensitive to whether the q{sup -} in the qqqqq{sup -} component is in the P-state or in the S-state, the calculated nucleon magnetic form factors are much closer to the empirical values in the case of the former configuration. In the case of the electric form factor of the proton, G{sub E}{sup p}(Q{sup 2}) a zero appears in the impulse approximation close to 10 GeV{sup 2}, when the q{sup -} is in the P-state. That configuration, which may be interpreted as a pion loop ('cloud') fluctuation, also leads to a clearly better description of the nucleon magnetic moments. When the amplitude of the sea-quark admixtures are set so as to ...

2007-07-15

241

The indoor environment and advanced ventilation systems; Binnenmilieu steeds afhankelijker van geavanceerde ventilatie  

Energy Technology Data Exchange (ETDEWEB)

A lower energy efficiency standard for buildings (EPC) can have a negative impact on thermal comfort and indoor air quality. Cooperation and integrated design are preconditions for a correct use, installation and maintenance of heating and ventilation systems in buildings. [Dutch] Er komt steeds meer kritiek op de wijze waarop in ons land woningen en gebouwen worden gebouwd. Op dit moment is het vooral woonhuisventilatie waar veel om te doen is. Van beleidsmakers tot aannemers en van Consumentenbond tot gezondheidsdiensten; iedereen vraagt zich af of we met vergaande isolatie onze woningen en gebouwen nog wel leefbaar houden. In dit artikel wordt een pleidooi gehouden voor onderlinge samenwerking en integraal ontwerp als randvoorwaarden voor een goede toepassing, installatie en onderhoud van verwarmings- en ventilatiesystemen in gebouwen.

2006-09-15

242

The effect of the changing microstructure on the fatigue behaviour during cyclic rolling contact loading  

Energy Technology Data Exchange (ETDEWEB)

During rolling contact fatigue of the inner rings of ball bearings three stages of material response can be distinguished, in terms of the volume that is plastically deformed upon overrolling. After a first stage of material strengthening during which a decrease occurs for the volume that is deformed plastically, an effectively stationary, second stage is entered which is eventually succeeded by a third stage exhibiting a pronounced increase of the volume that is deformed plastically upon overrolling, which leads to failure. It is suggested that carbon diffusion induced by local temperature peaks occurring at the moment of overrolling is the key mechanism leading to fatigue damage. The amount of decomposed retained austenite is a useful, practical parameter to assess fatigue life. It is shown that published ideas about the role of certain components of residual stress in enhancing fatigue life are not correct and that the so-called Palmgren-Miner rule, as applied ...

1997-04-01

243

The Kinematic Signature of Face-On Peanut-Shaped Bulges  

CERN Document Server

We present a kinematic diagnostic for peanut-shaped bulges in nearly face-on galaxies. The face-on view provides a novel perspective on peanuts which would allow study of their relation to bars and disks in greater detail than hitherto possible. The diagnostic is based on the fact that peanut shapes are associated with a flat density distribution in the vertical direction. We show that the kinematic signature corresponding to such a distribution is a minimum in the fourth-order Gauss-Hermite moment $s_4$. We demonstrate our method on $N$-body simulations of varying peanut strength, showing that strong peanuts can be recognized to inclinations $i \\simeq 30\\degrees$, regardless of the strength of the bar. We also consider compound systems in which a bulge is present in the initial conditions as may happen if bulges form at high redshift through mergers. We show that in this case, because the vertical structure of the bulge is not derived from that of the disk, that ...

2005-01-01

244

Studies of ultra-low energy electron-molecule collisions using very-high-n Rydberg atoms  

International Nuclear Information System (INIS)

Potassium atoms in selected high-lying np Rydberg states (80 #<=# n #<=# 400) are being used as a tool to examine electron-polar molecule collisions at ultra-low energies (#approx#80 #mu#eV - 1 meV). This energy regime has not been investigated previously and is of interest because the corresponding electron de Broglie wavelength is large, #approx#1300 - 330 Angstrom, and because the collision time is comparable to the period of molecular rotation. A variety of target molecules has been studied, including simple rotors such as HF, and more complex species such as NH_3, CH_3I, CH_2Br_2 and C_6H_5NO_2. These targets encompass a range of dipole moments and rotational behavior, but analysis of the data shows that in each case the cross section #sigma#(#epsilon#) for rotationally-inelastic electron-polar molecule scattering varies approximately as 1/#epsilon# where #epsilon# is the electron energy. Such threshold behavior is not predicted by the Born approximation ...

1993-05-16

245

Structure and Function Evolution of Thiolate Monolayers on Gold  

Energy Technology Data Exchange (ETDEWEB)

The use of n-alkanethiolate self-assembled monolayers on gold has blossomed in the past few years. These systems have functioned as models for common interfaces. Thiolate monolayers are ideal because they are easily modified before or after deposition. The works contained within this dissertation include interfacial characterization (inbred reflection absorption spectroscopy, ellipsometry, contact angle, scanning probe microscopy, and heterogeneous electron-transfer kinetics) and various modeling scenarios. The results of these characterizations present ground-breaking insights into the structure, function, and reproducible preparation of these monolayers. Surprisingly, three interfacial properties (electron-transfer, contact angle, and ellipsometry) were discovered to depend directly on the odd-even character of the monolayer components. Molecular modeling was utilized to investigate adlayer orientation, and suggests that these effects are adlayer structure specific. Finally, the ...

2006-05-01

246

Stable atomic structure and magnetism of Pt-Cr binary surface alloys on Pt(0 0 1): First-principle calculations  

International Nuclear Information System (INIS)

The possibility of Pt-Cr surface alloys formation on Pt(0 0 1) was investigated and their magnetism was calculated by the full-potential linearized augmented plane wave (FLAPW) method with eight different atomic configurations. The most stable structure was calculated to be the Pt-segregated L1_2 ferromagnetic surface alloy. A_3B types (L1_2 or D0_2_2) were more stable compared to AB types (L1_0). It implies that the A_3B type surface alloys may be formed when depositing a monolayer of Cr on Pt(0 0 1). It was found from the total energy calculations that there exists a strong tendency of the Pt segregation. The segregation further stabilizes the surface alloy significantly. The work function of the most stable surface alloy was calculated to be 6.02 eV and the magnetic moment of the surface Cr was much enhanced to 3.3 #mu# _B. It is a quite interesting finding that the coupling between Cr and Pt atoms on the surface plane is ferromagnetic in the Pt-segregated L1_2 ...

2006-09-01

247

Simulation tools and new developments of the molten salt fast reactor  

International Nuclear Information System (INIS)

Starting from the Molten Salt Breeder Reactor project of Oak-Ridge, we have performed parametric studies in terms of safety coefficients, reprocessing requirements and breeding capabilities. In the frame of this major re-evaluation of the molten salt reactor (MSR), we have developed a new concept called Molten Salt Fast Reactor or MSFR, based on the Thorium fuel cycle and a fast neutron spectrum. This concept has been selected for further studies by the MSR steering committee of the Generation IV International Forum in 2009. Our reactor's studies of the MSFR concept rely on numerical simulations making use of the MCNP neutron transport code coupled with a code for materials evolution which resolves the Bateman's equations giving the population of each nucleus inside each part of the reactor at each moment. Because of MSR's fundamental characteristics compared to classical solid-fuelled reactors, the classical Bateman equations have to be modified by adding two ...

248

Shell-model predictions for electromagnetic properties of N = 50 nuclei  

Energy Technology Data Exchange (ETDEWEB)

Predictions for E2, M1, and M4 transition rates and moments, together with examples of transition-charge densities, are presented for states of N = 50 nuclei. These predictions are based on one-body spectroscopic amplitudes obtained from the wave functions of a new N = 50 shell-model calculation which incorporates the 0f/sub 5/2/, 1p/sub 3/2/, 1p/sub 1/2/, and 0g/sub 9/2/ single-particle orbits and an empirically determined effective Hamiltonian for this space. The predictions are compared with experimental data, first in order to evaluate how well the model space, as applied by this Hamiltonian, accounts for observations, and then to assess the importance of configurations excluded from the model space and to determine the values of the operator renormalizations (effective charges and effective g factors) which optimally map the theoretical results onto the corresponding experimental values.

1988-12-01

249

Shape isomers: Mean-field description and beyond  

Energy Technology Data Exchange (ETDEWEB)

Nuclear Hartree-Fock (HF) + BCS calculations have led to predictions of shape isomerism in isotopes of Pt, Hg and Os nuclei. These have been confirmed through the observation of superdeformed rotational bands in {sup 190,{hor ellipsis},194}Hg. Encouraged by these measurements and similar observations in {sup 194}Pb, we have extended these calculations to a wide range of contiguous nuclei. These HF results, for {sup 192,194}Pt, {sup 190,{hor ellipsis},198}Hg and {sup 194}Pb, have been employed in a Generator Coordinate Method (GCM) calculation utilizing the quadrupole deformation as the generating variable. The resulting spectra confirm the conclusions drawn from the HF results and agree with those experiments which have been performed. Adding a phenomenological assumption for the moments of inertia of our GCM states, we can construct the radiative transitions within and out of the superdeformed band. The results are in good agreement with the observed de-population ...

1990-11-19

250

Seismic response of pile-supported structure considering nonlinearity of superstructure and pile, and liquefaction of surrounding ground; Shuhen jiban no ekijoka oyobi kui no hisenkeisei wo koryoshita kui shiji tatemono no jishin oto kaiseki  

Energy Technology Data Exchange (ETDEWEB)

Recent earthquake disasters have revealed the importance of countermeasures against soil Liquefaction in seismic design. In particular, the 1995 Hyogoken Nanbu earthquake caused several types of severe damages to pile foundations. This paper describes an analysis method for soil liquefaction using simple parameters such as SPT-N values and seismic response analyses for the pile-supported structure to consider soil-structure interaction effects and soil non-linearity using a modified Penzien model. It is important to find a way to determine the region of surrounding soil whose behavior is identical to that of piles. This paper adopts the thin layer element method to systematically determine the volume of the surrounding soil. The responses of pile-supported structure are similar, whether soil liquefaction and nonlinearity of pile are considered or not. However, the bending moment of pile become large as to soil liquefaction, and small as to nonlinearity of pile. ...

2000-01-10

251

Recent trends in heavy-fermion physics  

Energy Technology Data Exchange (ETDEWEB)

We discuss recent results obtained for the heavy-fermion metals UPd{sub 2}Al{sub 3} and YbRh{sub 2}Si{sub 2}. UPd{sub 2}Al{sub 3} is the first among all superconductors for which tunneling and inelastic neutron-scattering data highlight a non-phononic, i.e., magnetic-exciton mediated, pair state. YbRh{sub 2}Si{sub 2} represents a model system exhibiting pronounced non-Fermi liquid effects above a weak antiferromagnetic phase transition at T{sub N}=70 mK. Upon approaching the quantum critical point (T{sub N}{yields}0), by low doping with Ge, one observes for T<0.3 K disparate behavior in the temperature dependences of both the electrical resistivity and the electronic specific heat as well as a Curie-Weiss law in the uniform magnetic susceptibility, implying uncompensated large 4f moments. These observations indicate a break up of the composite quasiparticles into their local f-spin and itinerant conduction-electron parts.

2003-05-01

252

Radial distribution of superthermal electrons measured with ECE (abstract)  

International Nuclear Information System (INIS)

To aid in the study of lower hybrid current drive as a means of current profile control, the radial profile and velocity distribution of the fast current-carrying electrons and their time evolution must be known. As part of the recent effort to understand this fast electron transport, a diagnostic has been installed on PBX-M to measure the electron cyclotron emission from the fast electrons. An oblique horizontal view of upshifted cyclotron emission in the midplane can give radial as well as velocity space information about the fast electrons. Emission in X mode frequencies refracted by the right-hand cutoff is radially localized. The observed emission at a specific frequency comes only from the radial region r_t_u_r_n=#0. Emission measured by this new diagnostic has been found to be radially localized as predicted. It is also expected that localized moments of the distribution function may be obtained from these data. A superheterodyne receiver at 60--90 GHz has ...

0854-01-01

253

Quark and Gluon Tagging at the LHC  

CERN Document Server

Being able to distinguish light-quark jets from gluon jets on an event-by-event basis could significantly enhance the reach for many new physics searches at the Large Hadron Collider. Through an exhaustive search of existing and novel jet substructure observables, we find that a multivariate approach can filter out over 95% of the gluon jets while keeping more than half of the light-quark jets. Moreover, a combination of two simple variables, the charge track multiplicity and the pT-weighted linear radial moment (girth), can achieve similar results. While this pair appears very promising, our study is only Monte Carlo based, and other discriminants may work better with real data in a realistic experimental environment. To that end, we explore many other observables constructed using different jet sizes and parameters, and highlight those that deserve further theoretical and experimental scrutiny. Additional information, including distributions of around 10,000 ...

2011-01-01

254

Paramagnetic susceptibility of nonstoichiometric fluorides with the fluorite-type structure  

Energy Technology Data Exchange (ETDEWEB)

Magnetic properties of single crystals of nonstoichiometric fluorides M[sub 1-x]R[sub x]F[sub 2+x] (M = Ca, Sr, Ba; R = Ce, Pr, Nd, Gd, Ho, Er, Tm, Yb; with 0.05 [le] x [le] 0.28) with the fluorite-type structure have been studied for the first time. The magnetic susceptibility was measured using a Faraday balance in the 15-300 K temperature range. The samples are paramagnetic following the Curie-Weiss law. The values of paramagnetic Curie temperatures and effective magnetic moments of rare-earth ions have been found. Deviations of the temperature dependence of magnetic susceptibility from the Curie-Weiss law are observed for some nonstoichiometric fluorides at temperatures ranging from 60 to 85 K. Possible reaons for these deviations are discussed. Measurements of magnetic susceptibility provide an effective technique for a rapid and accurate determination of the concentration of rare-earth ions in nonstoichiometric fluorides.

1993-01-01

255

Orbital roulette: a new method of gravity estimation from observed motions  

CERN Document Server

The traditional way of estimating the gravitational field from observed motions of test objects is based on the virial relation between their kinetic and potential energy. We find a more efficient method. It is based on the natural presumption that the objects are observed at a random moment of time and therefore have random orbital time phases. The proposed estimator, which we call "orbital roulette", checks the randomness of the phases. The method has the following advantages: (1) It estimates accurately Keplerian (point-mass) potentials as well as non-Keplerian potentials where the unknown gravitating mass is distributed in space. (2) It is a complete statistical estimator: it checks a trial potential and accepts it or rules it out with a certain significance level; the best-fit measurement is thus supplemented with error bars at any confidence level. (3) It needs no a priori assumptions about the distribution of orbital parameters of the test bodies. We test ...

2004-01-01

256

On the temperature dependence of the magnetic excitations  

International Nuclear Information System (INIS)

We compare experimental data for temperature dependence of the magnetic order parameter and the magnetic excitations (spin waves) in materials with a quenched orbital moment and a well-defined spin quantum number. It is observed that the thermal decrease of the two quantities proceeds according to the same analytical function of the type y(T)=1-cT"#epsilon# with an identical exponent #epsilon#. This power function applies not only asymptotically for T->0 but holds over a wide temperature range. The exponent #epsilon# is universal, i.e. independent of spin order type and lattice symmetry and depends only on the dimensionality of the relevant interactions and on whether the spin quantum number is integer or half-integer. The different T"#epsilon# functions are identified as representations of stable universality classes. The fact that order parameter and magnetic excitations follow the same T"#epsilon# function shows that the two quantities belong to the same ...

2005-07-15

257

Nonlinear dynamic analysis of high energy line pipe whip  

International Nuclear Information System (INIS)

To facilitate potential cost savings in pipe whip protection design, TVA conducted a 1'' high pressure line break test to investigate the pipe whip behavior. The test results are available to EPRI as a data base for a generic study on nonlinear dynamic behavior of piping systems and pipe whip phenomena. This paper describes a nonlinear dynamic analysis of the TVA high energy line tests using ABAQUS-EPGEN code. The analysis considers the effects of large deformation and high strain rate on resisting moment and energy absorption capability of the analyzed piping system. The numerical results of impact forces, impact velocities, and reaction forces at pipe supports are compared to the TVA test data. The pipe whip impact time and forces have also been calculated per the current NRC guidelines and compared. The calculated pipe support reaction forces prior to impact have been found to be in good agreement with the TVA test data except for some peak values at the very ...

258

New constraints on the primordial black hole number density from Galactic gamma-ray astronomy  

CERN Document Server

Primordial black holes are unique probes of cosmology, general relativity, quantum gravity and non standard particle physics. They can be considered as the ultimate particle accelerator in their last (explosive) moments since they are supposed to reach, very briefly, the Planck temperature. Upper limits on the primordial black hole number density of mass $M_{\\star} = 5 10^{14}$ g, the Hawking mass (born in the big-bang terminating their life presently), is determined comparing their predicted cumulative $\\gamma$-ray emission, galaxy-wise, to the one observed by the EGRET satellite, once corrected for non thermal $\\gamma$-ray background emission induced by cosmic ray protons and electrons interacting with light and matter in the Milky Way. A model with free gas emissivities is used to map the Galaxy in the 100 MeV photon range, where the peak of the primordial black hole emission is expected. The best gas emissivities and additional model parameters are obtained ...

2009-01-01

259

Nature of magnetic coupling between Mn ions in as-grown Ga1-xMnxAs studied by x-ray magnetic circular dichroism  

International Nuclear Information System (INIS)

The magnetic properties of as-grown Ga1-xMnxAs have been investigated by the systematic temperature and magnetic field dependent soft x-ray magnetic circular dichroism (XMCD) measurements in the Mn L2,3 absorption edge region. The XMCD intensity at high temperatures obeys the Curie-Weiss law, but residual spin magnetic moment appears already around 100 K, significantly above Curie temperature (Tc), suggesting that short-range ferromagnetic correlations are developed significantly above Tc. The high-field magnetic susceptibility becomes T-independent below TC, indicating that the AF interaction between the substitutional Mn (Mnsub and interstitial Mn (Mnint) ions, which becomes strong as the Mn concentration x increases, exists and that the amount of the Mnint affects Tc. The present experimental findings should give valuable insight into the inhomogeneous magnetic properties of many DMS's. (author)

2009-07-01

260

Molybdenum complexes of biochemical interest. New coordination complexes of oxomolybdenum(V) with the tridentate ONO donor Schiff bases derived from salicylaldehydes and ethanolamine  

Energy Technology Data Exchange (ETDEWEB)

New oxomolybdenum(V) complexes MoOClL (where LH/sub 2/ = Schiff base) derived from ethanolamine and salicylaldehyde, 5-chlorosalicylaldehyde, 5-bromosalicylaldehyde, 5-nitrosalicylaldehyde, 3-ethoxysalicylaldehyde and 2-hydroxy-1-naphthaldehyde have been synthesized and characterised by elemental analyses, conductance, molecular weight, I.R. and electronic spectra and magnetic measurements. The Schiff bases behave as dibasic tridentate ONO donor ligands. The complexes are non-electrolytes and dimers. The complexes exhibit subnormal magnetic moments and are involved in antiferromagnetic exchange with S = 0 ground state. The complexes exhibit electronic spectral bands at ca. 13000 and ca. 17000 cm/sup -1/ due to the transitions dsub(xy)- > dsub(xz,yz) (/sup 2/B/sub 2/- > /sup 2/E) and dsub(xy)- > dsub(x2-y2) (/sup 2/B/sub 2/- > /sup 2/B/sub 1/), respectively. The ..nu..(Mo = O) frequency of the complexes is observed in the 900-970 cm/sup -1/ region. On ...

1985-02-01

261

Molybdenum complexes of biochemical interest. New coordination complexes of oxomolybdenum(V) with the tridentate ONO donor Schiff bases derived from salicylaldehydes and ethanolamine  

International Nuclear Information System (INIS)

New oxomolybdenum(V) complexes MoOClL (where LH_2 = Schiff base) derived from ethanolamine and salicylaldehyde, 5-chlorosalicylaldehyde, 5-bromosalicylaldehyde, 5-nitrosalicylaldehyde, 3-ethoxysalicylaldehyde and 2-hydroxy-1-naphthaldehyde have been synthesized and characterised by elemental analyses, conductance, molecular weight, i.r. and electronic spectra and magnetic measurements. The Schiff bases behave as dibasic tridentate ONO donor ligands. The complexes are non-electrolytes and dimers. The complexes exhibit subnormal magnetic moments and are involved in antiferromagnetic exchange with S = 0 ground state. The complexes exhibit electronic spectral bands at ca. 13000 and ca. 17000 cm"-"1 due to the transitions dsub(xy)->dsub(xz,yz) ("2B_2->"2E) and dsub(xy)->dsub(x2-y2) ("2B_2->"2B_1), respectively. The #nu#(Mo=O) frequency of the complexes is observed in the 900-970 cm"-"1 region. On the basis of the magnetic susceptibility, i.r. and molecular ...

1985-01-01

262

Moderately heavy, heavy-fermion compound YbPd_2Si_2 at low temperatures  

International Nuclear Information System (INIS)

The available experimental data on the specific heat, magnetic susceptibility, magnetization, valence, NMR Knight shift and relaxation rate, and the quadrupolar moment of YbPd_2Si_2 are examined within the framework of the single-ion Anderson model. Such an analysis has previously given excellent agreement between theory and experiment for numerous other light heavy-fermion compounds, where crystalline fields do not play a dominant role. For YbPd_2Si_2, substantial crystalline-field splittings make difficult a quantitative comparison with existing exact solutions of the Anderson model. Inconsistencies with the interpretation that a nearly degenerate ground quadruplet determines the low-temperature thermodynamics are pointed out. It is concluded that at least three of the four Kramers doublets participate in the low-T properties. These three doublets should have a splitting of the order of the Kondo temperature, i.e., about 100 K. A simple resonant-level model ...

263

Moderately heavy, heavy-fermion compound YbPd sub 2 Si sub 2 at low temperatures  

Energy Technology Data Exchange (ETDEWEB)

The available experimental data on the specific heat, magnetic susceptibility, magnetization, valence, NMR Knight shift and relaxation rate, and the quadrupolar moment of YbPd{sub 2}Si{sub 2} are examined within the framework of the single-ion Anderson model. Such an analysis has previously given excellent agreement between theory and experiment for numerous other light heavy-fermion compounds, where crystalline fields do not play a dominant role. For YbPd{sub 2}Si{sub 2}, substantial crystalline-field splittings make difficult a quantitative comparison with existing exact solutions of the Anderson model. Inconsistencies with the interpretation that a nearly degenerate ground quadruplet determines the low-temperature thermodynamics are pointed out. It is concluded that at least three of the four Kramers doublets participate in the low-{ital T} properties. These three doublets should have a splitting of the order of the Kondo temperature, i.e., about 100 K. A simple ...

1992-07-01

264

Microstructure and magnetic properties of nanocrystalline Fe75Si20M5 (M = Al, B, Cr) powders  

International Nuclear Information System (INIS)

Nanocrystalline Fe75Si20M5 (M = Al, B and Cr) powders were synthesized by mechanical alloying in a planetary ball mill from high purity elemental powders. Evolution of non-equilibrium solid solutions of ?-Fe[Si,(Al, B, Cr)] with a nanocrystalline structure was accompanied by the introduction of a large number of dislocation defects in the course of the milling process. Fe sites get substituted by Si and M (M = Al, B, Cr) atoms during the milling process. The structural change and the resulting disorder are reflected in the changes in the lattice parameter and average magnetic moment of the powders milled for various time periods. The effective magnetic anisotropy increases linearly with the milling time. An increase in coercivity with increasing milling time was observed which could be attributed to the introduction of dislocations and the reduction in the powder particle size during milling. The presence of dislocations and grain boundaries increases the ...

2008-08-21

265

Microscopic analysis of the /sup 88/Sr(p,p') reaction at E/sub p/ = 201. 5 MeV  

Energy Technology Data Exchange (ETDEWEB)

Differential cross sections for 201.5 MeV proton scattering form /sup 88/Sr were measured. From the analysis of the elastic data, no unique optical-model potential could be obtained, but the radial moments are well determined. In a macroscopic analysis of the collective states it turns out that if the optical potential and transition potential are chosen consistently, unambiguous potential deformation lengths can be obtained even though the optical potential is not unique. Taking into account the range and density dependence of the underlying effective interaction reliable neutron deformation lengths can be obtained. For inelastic transitions of various character microscopic distorted-wave calculations with a density-dependent interaction based on the Paris potential were performed. The nuclear structure was taken from one broken-pair calculations in a large model space, calibrated by (e,e') data. In general a good description is obtained for states with ...

1988-04-25

266

Microscopic analysis of the "8"8Sr(p,p') reaction at E_p = 201.5 MeV  

International Nuclear Information System (INIS)

Differential cross sections for 201.5 MeV proton scattering form "8"8Sr were measured. From the analysis of the elastic data, no unique optical-model potential could be obtained, but the radial moments are well determined. In a macroscopic analysis of the collective states it turns out that if the optical potential and transition potential are chosen consistently, unambiguous potential deformation lengths can be obtained even though the optical potential is not unique. Taking into account the range and density dependence of the underlying effective interaction reliable neutron deformation lengths can be obtained. For inelastic transitions of various character microscopic distorted-wave calculations with a density-dependent interaction based on the Paris potential were performed. The nuclear structure was taken from one broken-pair calculations in a large model space, calibrated by (e,e') data. In general a good description is obtained for states with spins ranging ...

267

Metastatic tumor of thoracic and lumbar spine: prospective study comparing the surgery and radiotherapy vs external immobilization with radiotherapy; Metastases do segmento toracico e lombar da coluna vertebral: estudo prospectivo comparativo entre o tratamento cirurgico e radioterapico com a imobilizacao externa e radioterapia  

Energy Technology Data Exchange (ETDEWEB)

Bone metastases at the thoracic and lumbar segment of the spine are usually presented with painful sensation and medullar compression. The treatment is based on the clinical and neurological conditions of the patient and the degree of tumor invasion. In the present study, 32 patients with spinal metastasis of thoracic and lumbar segment were prospectively analyzed. These patients were treated by decompression and internal stabilization followed by radiotherapy or irradiation with external immobilization. The election of the groups was in accordance with the tumor radiotherapy sensitivity, clinical conditions, spinal stability, medullar or nerve compression and patient's decision. The Frankel scale and pain visual test were applied at the moment of diagnosis and after 1 and 6 months. The surgical group had better results with preserving the ambulation longer and significant reduction of pain.(author)

2007-09-15

268

Magnetic resonance imaging in multiple sclerosis. Imagerie nouvelle par resonance magnetique nucleaire au cours de la sclerose en plaques  

Energy Technology Data Exchange (ETDEWEB)

Magnetic resonance imaging (MRI) has rapidly attained a major position among the examinations used in the diagnostic approach of multiple sclerosis because it is highly sensitive in demonstrating lesions. However, these lesional images may have several meanings, and there is the problem of distinguishing between oedema, which is said to reflect recent lesions, and gliosis which is thought to betray old lesions. The intrinsic MRI parameters studied (i.e. relaxation times) are unable to make this distinction, whereas it is provided by paramagnetic contrast media such as gadolinium. There is no correlation between the changes observed at MRI and the severity of the disease. Another problem is the accuracy of lesion localization, since visualization is predominantly macroscopic. This raises several questions about the demonstration of correlations between clinical signs and site of the lesion(s). At the moment, several teams of neuroradiologists are trying to find the ...

1991-09-15

269

Large deformation change in iridium isotopes from laser spectroscopy  

International Nuclear Information System (INIS)

Laser spectroscopy measurements have been performed on neutron-deficient iridium isotopes. The hyperfine structure and isotope shift of the optical Ir I transition 5d"76s"2 "4F_9_/_2#->#5d"76s6p "6F_1_1_/_2 have been studied for the "1"8"2"-"1"8"9Ir, "1"8"0Ir"m and "1"9"1","1"9"3Ir isotopes. The nuclear magnetic and quadrupole moments were obtained from the hyperfine splitting measurements and the changes of the mean square charge radii from the isotope shift measurements. A large deformation change between "1"8"7Ir and "1"8"6Ir and between "1"8"6Ir"m and "1"8"6Ir"g has been observed.

1999-11-16

270

Kondo effect and impurity-impurity interaction in (La, Ce)B_6 alloys  

International Nuclear Information System (INIS)

Measurements of the magnetic susceptibility betweeen 0.03 and 300 K and of the magnetization between 0.05 and 10 K for magnetic fields up to 60kOe have been used to investigate effects from the interaction between the conduction electrons and local magnetic moments in (Lasub(1-x)Cesub(x))B_6 alloys (0.0007<=x<=0.10). For Ce concentrations x<0.006 the data show Kondo-type single impurity behaviour at low temperatures with a transition from a magnetic to a non-magnetic regime of the Ce ions. In the magnetic regime the impurity susceptibility follows a Curie-Weiss law, and in the non-magnetic regime it varies with T"2. An external magnetic field gradually restores the free-ion behaviour of the Ce impurities. For more concentrated alloys interactions between the impurities are observed. The RKKY interaction strength derived is more than two orders of magnitude smaller than in the Kondo system CuFe. Values of the s-f exchange integral, J, estimated from both ...

1978-01-01

271

Isotope shift measurements at the {sup 242{ital f}}Am fission isomer  

Energy Technology Data Exchange (ETDEWEB)

Isotope shift measurements have been performed for the {sup 242{ital f}}Am fission isomer with target production rates of only a few per second. The method is based on resonance ionization spectroscopy (RIS) in a buffer gas cell with radioactive decay detection of the ionization process (RADRIS). A relative isotope shift ratio X{sub {ital exp}}=IS{sup 242{ital f},241}/IS{sup 243,241}=41.7{plus_minus}0.9 has been measured for the 500.02 nm transition corresponding to a nuclear parameter A{sup 242{ital f},241}=(5.4{plus_minus}0.3) fm{sup 2}. A preliminary analysis of the quadrupole moment based on the deformed Fermi model of the nuclear charge distribution results in Q{sub 20}=35.9{plus_minus}1.1({sup +0.3}{sub {minus}0.7}) {sub model} eb. {copyright} 1995 {ital American} {ital Institute} {ital of} {ital Physics}

1995-04-01

272

Investigations of Pulsed Plasma Streams Generated by 'Prosvet' device Operated with Different Gases  

International Nuclear Information System (INIS)

The paper presents the investigations of plasma streams generated by pulsed plasma gun 'Prosvet' operated with different gases: krypton (m=84) and helium (m=4). Contour parameters of working gas spectral lines (full intensities and half-widths) are used for determination of spatial distributions of the electron density and temperature. Temporal distributions of the spectral lines intensities (both neutrals and ions of working gas), impurity spectral lines and continuum intensities are analyzed. Plasma stream velocity was estimated by time-of-flight method between two monochromators (MUM) connected with photo-multiplier. longitudinal distributions of the plasma pressure for different time moments and varied distances from the accelerator output have been used for investigation of the plasma stream dynamics and study the plasma compression in the focus region for different operational regimes of plasma accelerator. Experiments show that operation regime of the ...

2006-01-01

273

Inelastic electron--dipole-molecule scattering at sub-milli-electron-volt energies: Possible role of dipole-supported states  

International Nuclear Information System (INIS)

Studies of collisions between Rydberg atoms with values of principal quantum number n in the range 100 approx-lt n approx-lt 400 and H_2S and C_6H_5NO_2 are reported. These targets were selected because they have very different dipole moments: 0.97 and 4.22 D, respectively. Analysis of the data using the essentially-free-electron model shows that at micro-electron-volt energies the cross sections for rotationally inelastic electron scattering by these targets have very different energy dependences. This difference suggests that, in the case of C_6H_5NO_2, dipole-supported states might be important in the scattering. To examine this further, the data are compared with the results of calculations using a free-electron cross section that assumes the presence of dipole-supported states, and it is demonstrated that, with a reasonable choice of parameters, it is possible to reproduce the experimental observations.

274

ISR Hadron Production in e+e- Annihilations and Meson-Photon Transition Form Factors  

CERN Document Server

We present several recent results from the BaBar collaboration in the areas of initial state radiation physics and transition form factors. An updated study of the processes e+e- -> K+K-pi+pi- and e+e- -> K+K-pi0pi0 provides an improved understanding of the Y(2175) meson. A very precise study of the process e+e- -> pi+pi- improves the precision on the calculated anomalous magnetic moment of the muon and provides by far the best information on excited rho states. Our previous measurements of the timelike transition form factors (TFF) of the eta and eta' mesons at Q^2=112 GeV^2, combined with new measurements of the their spacelike TFFs and those of the pi0 and eta_c mesons, provide powerful tests of QCD and models of the distribution amplitudes of quarks inside these mesons. The eta_c TFF shows the expected behavior over the Q^2 range 1-50 GeV^2, and we are sensitive to next-to-leading-order QCD corrections. The eta and eta' TFFs are consistent with ...

2011-01-01

275

High resolution spectroscopy of second overtone transitions in solid parahydrogen  

Energy Technology Data Exchange (ETDEWEB)

The high resolution spectrum of the parahydrogen Q{sub 3}(0) transition at 11758 cm{sup -1} has allowed specific quantum state assignment of the ten lines which compose this transition. The transition cannot occur unless a dipole moment is induced in the parahydrogen by an external field. The quadrupole field of an impurity o-H{sub 2} molecule provides this field, and the transition occurs in the orientationally dependent field of the orthohydrogen molecule. Transitions induced by the quadrupolar field of the J=1 H{sub 2} in the nearest neighbor as well as in the next nearest neighbor shells have been observed. By lowering the impurity orthohydrogen concentration, the authors have observed lines with linewidths of approximately 15 MHz hwhm with a Ti:Sapphire laser having a sensitivity of 3x10{sup -5} ({Delta}I/I) using the toneburst method. Additionally, the second vibrational overtone of the impurity orthohydrogen molecule (Q{sub 3}(1)) has been observed at ...

1995-12-31

276

Gear fault detection using customized multiwavelet lifting schemes  

Science.gov (United States)

Fault symptoms of running gearboxes must be detected as early as possible to avoid serious accidents. Diverse advanced methods are developed for this challenging task. However, for multiwavelet transforms, the fixed basis functions independent of the input dynamic response signals will possibly reduce the accuracy of fault diagnosis. Meanwhile, for multiwavelet denoising technique, the universal threshold denoising tends to overkill important but weak features in gear fault diagnosis. To overcome the shortcoming, a novel method incorporating customized (i.e., signal-based) multiwavelet lifting schemes with sliding window denoising is proposed in this paper. On the basis of Hermite spline interpolation, various vector prediction and update operators with the desirable properties of biorthogonality, symmetry, short support and vanishing moments are constructed. The customized lifting-based multiwavelets for feature matching are chosen by the minimum entropy ...

2010-07-01

277

From high enriched to low enriched uranium fuel in research reactors  

International Nuclear Information System (INIS)

Since the 1970's, global efforts have been going on to replace the high-enriched (>90% "2"3"5U), low-density UAlx research reactor fuel with high-density, low enriched (<20% "2"3"5U) replacements. This search is driven by the attempt to reduce the civil use of high-enriched material because of proliferation risks and terrorist threats. American initiatives, such as the Global Threat Reduction Initiative (GTRI) and the Reduced Enrichment for Research and Test Reactors (RERTR) program have triggered the development of reliable low-enriched fuel types for these reactors, which can replace the high enriched ones without loss of performance. Most success has presently been obtained with U_3Si_2 dispersion fuel, which is currently used in many research reactors in the world. However, efforts to search for a replacement with even higher density, which will also allow the conversion of some high flux research reactors that currently cannot change to U_3Si_2 (eg. BR2 in Belgium), have ...

278

Fragment angular momenta in low and medium energy fission of /sup 242/Pu  

Energy Technology Data Exchange (ETDEWEB)

Independent isomeric yield ratios of /sup 128/Sb were determined radiochemically in the thermal neutron induced fission of /sup 241/Pu and 34 MeV alpha particle induced fission of /sup 238/U, both involving the same compound nucleus (/sup 242/Pu). Fragment angular momenta estimated from the measured isomer ratios using the statistical model analysis showed significantly larger fragment angular momenta in the medium energy fissioning system compared to the low energy fissioning system. This has been attributed to the effect of higher excitation energy and angular momentum in the entrance channel leading to increased fragment temperature, moments of inertia and angular velocity. An attempt was made to calculate the fragment angular momentum in the medium energy fission using the Fermi gas model for the fissioning nucleus, taking into account the multichance fission, saddle shapes of the fissioning nuclei and the angular velocity components of the fissioning nuclei ...

1987-06-01

279

FIB implantation induced site-selectively grown self-assembled InAs QDs in a light emitting #mu#-diode  

International Nuclear Information System (INIS)

We present an approach for fabrication of intentionally positioned epitaxial InAs QDs in a micron sized light emitting diode. For site-selective growth, a combination of molecular beam epitaxy (MBE) and focused ion beam (FIB) implantation technology in an all-ultra-high-vacuum (UHV) setup has been employed. Single dot occupancy of almost 55 % on FIB patterned nano-depressions was successfully achieved. Thereafter, carrier injection and subsequent radiative recombination from the positioned InAs/GaAs self-assembled QDs was investigated by embedding these QDs in the intrinsic part of a GaAs-based micron sized p-i-n junction device. Few or single dot are expected to be electrically addressed in these devices. We report results from electroluminescence (EL) measurement which proves the single dot characteristics of our device. The EL spectra consist of sharp emission lines and their dependence on injection current shows linear behavior for exciton and quadratic behavior for biexciton ...

2010-03-21

280

Evaluation of a stack: A concrete chimney with brick liner  

Energy Technology Data Exchange (ETDEWEB)

A 200 ft. tall stack, consisting of a concrete chimney with an independent acid proof brick liner built in the 1950`s, serving the Separations facility at the Savannah River Site (SRS), was evaluated for the performance category 3 (PC3) level of Natural Phenomena Hazards (NPH) effects. The inelastic energy absorption capacity of the concrete chimney was considered in the evaluation of the earthquake resistance, in particular, to compute the F{sub {mu}} factor. The calculated value of F{sub {mu}} exceeded 3.0, while the seismic demand for the PC3 level, using an F{sub {mu}} value of 1.5, was found to be less than the capacity of the concrete chimney. The capacity formulation of ACI 307 was modified to incorporate the effect of an after design opening on the tension side. There are considerable uncertainties in determining the earthquake resistance of the independent brick liner. The critical liner section, located at the bottom of the breeching opening, does not meet the current ...

1995-12-31

281

Elephant's foot phenomenon in liquid storage tanks  

Energy Technology Data Exchange (ETDEWEB)

This paper presents a method for analyzing the seismic response of a flat bottomed cylindrical liquid storage tank to vertical earthquake excitation. Here, vertical earthquake acceleration is considered to correspond to an increase in the density of a stored liquid. Taking into account the vertical and horizontal earthquake loads, hydrostatic pressure, and considering restrictive moment and shear forces at shell-bottom welded joint, the author has calculated circumferential and longitudinal stresses. These are combined to more accurately approximate the stresses at the base shell course. The calculated result closely conforms to the actual damage, termed ''elephant's foot,'' observed in the fuel storage tanks damaged in the Tangshan earthquake. This result shows that the ''elephant's foot'' phenomenon is not caused by buckling of the tank shell due to longitudinal compressive ...

1983-01-01

282

Direct observation of ordered orbital of YTiO_3 by the X-ray magnetic diffraction technique  

International Nuclear Information System (INIS)

X-ray magnetic diffraction (XMD) technique was applied to an orbital ordering compound of ferromagnetic YTiO_3 for the first time. The orbital-magnetic form factor #mu# _L(k) and the spin-magnetic form factor #mu# _S(k) were independently measured by utilizing the LS separation ability of the XMD. The #mu# _L(k) was measured for ten reciprocal-lattice points. No significant values of the #mu# _L(k) were observed for most of the reciprocal-lattice points within the estimated statistical errors, which suggested quenching of the orbital moment. The #mu# _S(k) was measured for 22 reciprocal-lattice points. Fourier synthesis of the #mu# _S(k) gave the spin density distribution m _S(r) in the real space. The obtained m _S(r) map shows the characteristic feature of the electron distribution of 3d electron in the t_2_g state of a Ti atom coordinated by O"2"- ions, in which the electrons are distributed away from the negative O"2"- ions. It is concluded that the electron ...

2005-08-01

283

Crystal-field excitations in uranium dioxide  

Energy Technology Data Exchange (ETDEWEB)

The energy levels of the configuration f{sup 2} in an eight-fold cubic crystal field (CF) have been calculated, and the results are used to explain the experimental spectrum of UO{sub 2}. The fourth-order CF potential turns out to be much smaller than usually assumed for this compound. This has an effect of reducing the J-mixing in the wavefunctions, particularly in the case of the ground state wavefunction. In spite of the strength of the CF, the ground state vertical stroke {sup 3}H{sub 4}T{sub 2} right angle is found to be modified only slightly by the J-mixing effect; it consists of 89.4% {sup 3}He{sub 4}, and the remaining eleven components make up the rest. Very good correlation is obtained between the experimental and simulated energy-level schemes. The predominance of {sup 3}H{sub 4} in the ground state consequently increases the value of the calculated effective magnetic moment. The results are compared with our previous predictions about the system, and ...

1998-04-13

284

Crystal-field excitations in uranium dioxide  

International Nuclear Information System (INIS)

The energy levels of the configuration f"2 in an eight-fold cubic crystal field (CF) have been calculated, and the results are used to explain the experimental spectrum of UO_2. The fourth-order CF potential turns out to be much smaller than usually assumed for this compound. This has an effect of reducing the J-mixing in the wavefunctions, particularly in the case of the ground state wavefunction. In spite of the strength of the CF, the ground state vertical stroke "3H_4T_2 right angle is found to be modified only slightly by the J-mixing effect; it consists of 89.4% "3He_4, and the remaining eleven components make up the rest. Very good correlation is obtained between the experimental and simulated energy-level schemes. The predominance of "3H_4 in the ground state consequently increases the value of the calculated effective magnetic moment. The results are compared with our previous predictions about the system, and relevant conclusions drawn in the light of ...

1998-04-01

285

Crystal electric field excitations in the cerium compound CeRh{sub 3}B{sub 2} studied by inelastic neutron scattering  

Energy Technology Data Exchange (ETDEWEB)

We have performed inelastic neutron scattering (INS) experiments on CeRh{sub 3}B{sub 2} at various temperatures to obtain direct information on the crystal electric field (CEF) in this compound, which exhibits some very peculiar magnetic properties for a Ce system: it is ferromagnetic with an unusually high Curie temperature (115 K), which contrasts with a strongly reduced and anisotropic magnetization (0.4 {mu}{sub B}/fu within the c-plane of the hexagonal structure). Measurements with high incident energies show only one well defined magnetic excitation around 150 meV, its exact position varying with the temperature. These results, combined with our previous data of magnetization and magnetic form factor, have permitted us to determine the CEF energy level scheme taking into account the two J multiplets of the Ce{sup 3+} ion. Information on the ground state (quasielastic contribution and ground state moment) has also been obtained by experiments at low incident ...

2007-12-19

286

Crystal electric field excitations in the cerium compound CeRh_3B_2 studied by inelastic neutron scattering  

International Nuclear Information System (INIS)

We have performed inelastic neutron scattering (INS) experiments on CeRh_3B_2 at various temperatures to obtain direct information on the crystal electric field (CEF) in this compound, which exhibits some very peculiar magnetic properties for a Ce system: it is ferromagnetic with an unusually high Curie temperature (115 K), which contrasts with a strongly reduced and anisotropic magnetization (0.4 #mu#_B/fu within the c-plane of the hexagonal structure). Measurements with high incident energies show only one well defined magnetic excitation around 150 meV, its exact position varying with the temperature. These results, combined with our previous data of magnetization and magnetic form factor, have permitted us to determine the CEF energy level scheme taking into account the two J multiplets of the Ce"3"+ ion. Information on the ground state (quasielastic contribution and ground state moment) has also been obtained by experiments at low incident energies in the ...

2007-12-19

287

Controlling Schottky energy barriers in organic electronic devices using self-assembled monolayers  

Energy Technology Data Exchange (ETDEWEB)

We demonstrate tuning of Schottky energy barriers in organic electronic devices by utilizing chemically tailored electrodes. The Schottky energy barrier of Ag on poly[2-methoxy], 5-(2{prime}-ethyl-hexyloxy)- 1,4-phenylene was tuned over a range of more than 1 eV by using self-assembled monolayers (SAM{close_quote}s) to attach oriented dipole layers to the Ag prior to device fabrication. Kelvin probe measurements were used to determine the effect of the SAM{close_quote}s on the Ag surface potential. {ital Ab} {ital initio} Hartree-Fock calculations of the molecular dipole moments successfully describe the surface potential changes. The chemically tailored electrodes were then incorporated in organic diode structures and changes in the metal/organic Schottky energy barriers were measured using an electroabsorption technique. These results demonstrate the use of self-assembled monolayers to control metal/organic interfacial electronic properties. They establish a ...

1996-11-01

288

Control of adsorption by microwave irradiation; Maikuroha nado wo mochiita gas no kyuchaku datsuri seigyo  

Energy Technology Data Exchange (ETDEWEB)

Introduced herein is microwave irradiation for the adsorption and desorption of environmental pollutants. Microwaves may be used in two ways, other than through elevation of temperature of a system as a whole with the adsorbent such as activated carbon serving as the heating medium. The first is the application by which desorption is caused to take place of specified molecules. For example, zeolite that has adsorbed water is regenerated when it is irradiated with microwaves in a stream of cooling gas. This is because only the moisture is heated since zeolite is a non-carbon adsorbent that absorbs microwaves but a little. Another case is reported in which microwaves are utilized to desorb H2S, H2O, CO, etc., from molecular sieves. In the second application, coexisting materials different in absorptivity are exposed to irradiation. The adsorption of microwave-absorbent materials is inhibited while that of the others is accelerated. For example, the adsorption of chlorofluorocarbon from a ...

1997-01-25

289

Computational study of jet interaction flow field with and without incidence  

International Nuclear Information System (INIS)

The objective was to study the interaction of a side jet with the incoming supersonic flow and hypersonic flow. Qualitatively same Cp trends have been obtained as found experimentally. Also in aerodynamic coefficients side jet interaction results in additional pitching moment which is because of the high pressure region in upstream of the jet and a low pressure region in the downstream of the jet. Also jet interaction results in the rise in the lift coefficient. Whereas in the incidence case, simulation has been performed for the hypersonic flows over a biconic body with supersonic lateral jet at Mach 9.7 and incidence of 0"o to incidence of -12"o and 12"o. The results obtained were compared with the experimental and CFD code CFL3D results. PAK-3D over predicts the surface pressure as compared to the CFL3D and experimental results, whereas the qualitative trends are the same. Finally the integrated aerodynamic force coefficients were compared with CFL3D predicted ...

2004-05-09

290

Can a model-independent analysis be made for the matter distribution of "4"0Ca from 166 MeV #alpha# particle scattering  

International Nuclear Information System (INIS)

It is proposed to extract, independently of any nuclear model, the "4"0Ca matter density from an analysis of the elastic scattering of "1"6"6 MeV alpha particles. The scattering is described using an optical potential whose real part is evaluated by folding the matter density with a nucleon-alpha interaction. Following the procedure proposed by Sick (Nucl. Phys. A; 218: 509 (1974)) and Phys. Lett.; 44B; 62 (1975)) for the analysis of electron scattering data, the density is represented by a sum of gaussians whose amplitudes are deduced in fitting, via a chi"2 minimization, the experimental cross section data. This method determines the envelope of densities for different parameters of gaussians: width, spacing. The envelope of the moments of these densities are presented and the root-mean-square radius is extracted. It is concluded that only the nuclear surface is well studied by the alpha particle scattering. (author).

291

Anisotropy in Magnetic Properties and Electronic Structure of Single Crystal LiFePO4  

Energy Technology Data Exchange (ETDEWEB)

We report the experimental and theoretical results on the anisotropies in the magnetic properties and x-ray absorption spectra of single-crystal LiFePO4. A mean-field theory is developed to explain the observed strong anisotropies in Lande g-factor, paramagnetic Curie temperature, and effective moment for LiFePO4 single crystals. The values of the in-plane nearest- and next-nearest-neighbor spin exchange (J1 and J2), interplane spin exchange (J{perpendicular}), and single-ion anisotropy (D), obtained recently from neutron scattering measurements, are used for calculating the Curie temperatures with the formulas derived from the mean-field Hamiltonian. It is found that the calculated Curie temperatures match well with that obtained by fitting the magnetic susceptibility curves to the modified Curie-Weiss law. For the polarized Fe K-edge x-ray absorption spectra of single-crystal LiFePO4, a different feature assignment for the 1s4p transition features is proposed and ...

2008-01-01

292

An objective indicator for two-phase flow pattern transition  

Energy Technology Data Exchange (ETDEWEB)

This work concerns the development of a methodology the objective of which is to characterize and diagnose two-phase flow regime transitions. The approach is based on the fundamental assumption that a transition flow is less stationary than a flow with an established regime. During the first time, the efforts focused on: (1) the design and construction of an experimental loop, allowing to reproduce the main horizontal two-phase flow patterns, in a stable and controlled way; (2) the design and construction of an electrical impedance probe, providing an imaged information of the spatial phase distribution in the pipe; and (3) the systematic study of the joint time-frequency and time-scale analysis methods, which permitted to define an adequate parameter quantifying the unstationarity degree. During the second time, in order to verify the fundamental assumption, a series of experiments were conducted, the objective of which was to demonstrate the correlation between unstationarity and ...

1998-08-01

293

An objective indicator for two-phase flow pattern transition  

International Nuclear Information System (INIS)

This work concerns the development of a methodology the objective of which is to characterize and diagnose two-phase flow regime transitions. The approach is based on the fundamental assumption that a transition flow is less stationary than a flow with an established regime. During the first time, the efforts focused on: (1) the design and construction of an experimental loop, allowing to reproduce the main horizontal two-phase flow patterns, in a stable and controlled way; (2) the design and construction of an electrical impedance probe, providing an imaged information of the spatial phase distribution in the pipe; and (3) the systematic study of the joint time-frequency and time-scale analysis methods, which permitted to define an adequate parameter quantifying the unstationarity degree. During the second time, in order to verify the fundamental assumption, a series of experiments were conducted, the objective of which was to demonstrate the correlation between unstationarity and ...

1998-08-01

294

A gas-jet ECR ion source at TRIGA-SPEC  

International Nuclear Information System (INIS)

The TRIGA-SPEC experiment has been installed recently at the research reactor TRIGA Mainz. Ground state properties like masses, charge radii, spins, and moments of short-lived nuclides can be determined with very-high precision using the Penning trap mass spectrometer TRIGA-TRAP, and the collinear laser spectroscopy setup TRIGA-LASER. Short-lived neutron-rich radionuclides in the mass range 80 < A < 140 are produced by thermal neutron induced fission of e.g. U-235, Pu-239 or Cf-249, respectively. For the extraction and ionization of the fission products a gas-jet system is coupled to a 2.45-GHz ECR ion source for the production of singly charged ions. The gas-jet has been tested on-line and fission products have been extracted. First off-line tests of the ion source have been performed successfully with argon gas. The results of the commissioning test of the ion source and the on-line coupling of the experiments are presented.

2010-03-08

295

A full-potential linearized augmented plane wave (FP-LAPW) study of atomic carbon, nitrogen, and oxygen chemisorption on the (1 0 0) surface of #delta#-Pu  

International Nuclear Information System (INIS)

Fully relativistic full-potential density functional calculations with an all-electron linearized augmented plane wave plus local orbitals method have been performed to investigate the electronic and geometric structures of atomic carbon, nitrogen, and oxygen chemisorption on the (1 0 0) surface of #delta#-Pu. For all chemisorption processes, the center adsorption site is found to be the most preferred site with chemisorption energies of 7.964, 7.665, and 8.335 eV for the C, N, and O adatoms, respectively. The respective optimized distances of the C, N, and O adatoms from the surface were found to be 0.26, 0.35, and 0.48 A. The work functions and the net magnet moments, respectively, increased and decreased in all cases compared with the bare #delta#-Pu (1 0 0) surface. In particular, the work function shift is largest for the least preferred top site and lowest for the most preferred center site. A detailed analysis of partial charges inside the atomic spheres, ...

2007-04-15

296

Magnetic properties and magnetic ordering in the rare earth molybdenum(IV) pyrochlores: R_2Mo_2O_7  

International Nuclear Information System (INIS)

The series of cubic pyrochlore structure compounds, R_2Mo_2O_7 (R = Nd-Yb, Y; R not= Eu), were prepared as single phase materials by solid state reaction between R_2O_3 and MoO_2 at 1400 "0C in a CO/CO_2 = 1 buffer gas atmosphere. Lattice constants obtained from X-ray powder data compare well with results from previous studies. Magnetic susceptibility and magnetization data were obtained for all samples between 300 K and 4.2 K (700 K for R = Gd) and a range of applied fields. For R = Nd, Sm, and Gd magnetic ordering is observed at 97 K, 93 K and 83 K respectively which is assigned to ferromagnetism on the Mo(IV) sublattice. The Mo(IV) moment in the ordered state is about 1 #mu#/sub B/. At low temperatures, the Gd(III) and Mo(IV) moments are apparently coupled feromagnetically in Gd_2Mo_2O_7 yet the high temperature susceptibility data seem to indicate a ferrimagnetic (antiparallel) Gd(III)-Mo(IV) coupling. The low-temperature magnetic ...

1986-01-01

297

Weld integrity of the superconducting cable aluminium jackets of W7-X  

Energy Technology Data Exchange (ETDEWEB)

The Wendelstein 7-X (W7-X) modular stellarator is under construction at the Max-Planck-Institut fuer Plasmaphysik in Greifswald, Germany. The W7-X magnet system contains 70 coils made up from helium cooled superconducting cables in aluminium alloy (EN AW-6063) jackets. Several hundred connections of the jacket to the cable joints are made by aluminium-to-aluminium welds. Due to geometrical and thermal boundary conditions these welds cannot be accomplished free from defects. Microscopic analyses of the welds show that a variety of small flaws such as cracks and pores develop during welding. The welds have thus to be dimensioned accordingly, and appropriate weld qualification, investigation and testing has to be done in order not to jeopardise the structural integrity and leak tightness. The weld is mechanically loaded during cool-down due to the difference in thermal contractions between the GRP insulation and the aluminium, and during operation by bending moments ...

2009-06-15

298

Weld integrity of the superconducting cable aluminium jackets of W7-X  

International Nuclear Information System (INIS)

The Wendelstein 7-X (W7-X) modular stellarator is under construction at the Max-Planck-Institut fuer Plasmaphysik in Greifswald, Germany. The W7-X magnet system contains 70 coils made up from helium cooled superconducting cables in aluminium alloy (EN AW-6063) jackets. Several hundred connections of the jacket to the cable joints are made by aluminium-to-aluminium welds. Due to geometrical and thermal boundary conditions these welds cannot be accomplished free from defects. Microscopic analyses of the welds show that a variety of small flaws such as cracks and pores develop during welding. The welds have thus to be dimensioned accordingly, and appropriate weld qualification, investigation and testing has to be done in order not to jeopardise the structural integrity and leak tightness. The weld is mechanically loaded during cool-down due to the difference in thermal contractions between the GRP insulation and the aluminium, and during operation by bending moments ...

2009-06-01

299

Understanding and predicting soot generation in turbulent non-premixed jet flames.  

Energy Technology Data Exchange (ETDEWEB)

This report documents the results of a project funded by DoD's Strategic Environmental Research and Development Program (SERDP) on the science behind development of predictive models for soot emission from gas turbine engines. Measurements of soot formation were performed in laminar flat premixed flames and turbulent non-premixed jet flames at 1 atm pressure and in turbulent liquid spray flames under representative conditions for takeoff in a gas turbine engine. The laminar flames and open jet flames used both ethylene and a prevaporized JP-8 surrogate fuel composed of n-dodecane and m-xylene. The pressurized turbulent jet flame measurements used the JP-8 surrogate fuel and compared its combustion and sooting characteristics to a world-average JP-8 fuel sample. The pressurized jet flame measurements demonstrated that the surrogate was representative of JP-8, with a somewhat higher tendency to soot formation. The premixed flame measurements revealed that flame temperature has a ...

2010-10-01

300

Ultracold neutrons  

International Nuclear Information System (INIS)

In 1959 Zeldovich pointed out to the possibility of storage in a closed vessel of very slow neutrons with energies below less than or equal to 10"-"7 eV noting that one may achieve the storage time up to the lifetime of a free neutron before #beta#-decay (approx.10"3 sec). This possibility is due to the effective repulsing potential which describes the interaction of slow neutrons with many substances employing a strong suppression of inelastic processes in the reflection of ultracold neutrons (UCN). In a series of experiments beginning 1968 the effective methods were developed of obtaining pure UCN beams from the maxwellian spectrum of thermal neutrons. The UCN beams of intensity about 10"3 n/sec and density up to 10"2 n/liter were obtained at the reactors with thermal neutron flux of 5 x 10"1"3 n/cm"2 sec. Such UCN beam parameters allow to measure easily the UCN storage time in different vessels and under different conditions. Maximum UCN storage time achieved in the experiments is ...

1976-07-06

301

Transverse Quark Spin Effects and the Flavor Dependence of the Boer-Mulders Function  

Energy Technology Data Exchange (ETDEWEB)

The naive time reversal odd (T-odd) parton distribution $h_{1}^{\\perp}$, the so-called Boer-Mulders function, for both $u$- and $d$-quarks is considered in the diquark spectator model. While other approaches give evidence that the signs of the Boer-Mulders function for both flavors $u$ and $d$ are the same and negative, previous caculations in the diquark-spectator model found $h_{1}^{\\perp(u)}$ and $h_{1}^{\\perp(d)}$ have differnet signs. The flavor dependence is of significance for the analysis of the azimuthal $\\cos(2\\phi)$ asymmetries in unpolarized SIDIS and DY-processes, as well as for the overall physical understanding of the distribution of transversely polarized quarks in unpolarized nucleons. We find substantial differences with previous work. In particular we obtain estimates of the zeroth, half and first moments of Boer-Mulders functions that are negative over the full range in Bjorken $x$ for both the up and down quarks. In conjunction with the ...

2007-07-30

302

The gamma transition from the 55/22"+[402] state to the 77/22"+[404] state in "1"7"7Ta  

International Nuclear Information System (INIS)

An experimental investigation of the 70.5 keV #gamma#-ray transition from the 55/22"+[402] state to the 77/22"+[404] ground state in "1"7"7Ta was made. The half-life and magnetic moment of the initial state were found to be 73+-5 ns and 4.7+-0.5 #mu#sub(N) respectively. The E2/M1 mixing ratio of the transition was determined to be -0.10+-0.04. The reduced transition probabilities, B(E2) and B(M1), were found to be 2.9+-2.3e"2.fm"4 and (1.1+-0.1)x10"-"4#mu#sub(N)"2, respectively, and the M1 penetration parameter was determined to be 6+-2. The Coriolis mixing amplitude of the 75/22"+[402] state in the 77/22"+[404] ground state was determined from the B(E2) value to be -0.011+-0.004. It was found that the experimental value of the Coriolis matrix element <5/2"+/j-/7/2"+>sub(exp) was one-tenth of that calculated using the Nilsson wave function. The coefficient k_2, introduced by Wahlborn et al., was re-analyzed using the present experimental results and found to ...

303

The Application of Spatial Signature Analysis to Electrical Test Data: Validation Study  

Energy Technology Data Exchange (ETDEWEB)

This paper presents the results of the Spatial Signature Analysis (SSA) Electrical-test (e-test) validation study that was conducted between February and June, 1998. SSA is an automated procedure developed by researchers at the Oak Ridge National Laboratory to address the issue of intelligent data reduction while providing feedback on current manufacturing processes. SSA was initially developed to automate the analysis of optical defect data. Optical defects can form groups, or clusters, which may have a distinct shape. These patterns can reveal information about the manufacturing process. Optical defect SSA uses image processing algorithms and a classifier system to interpret and identify these patterns, or signatures. SSA has been extended to analyze and interpret electrical test data. The algorithms used for optical defect SSA have been adapted and applied to e-test binmaps. An image of the binmap is created, and features such as geometric and invariant moments ...

1999-03-15

304

Ternary stannides RE_3Ru_4Sn_1_3 (RE = La, Ce, Pr, Nd). Structure, magnetic properties, and "1"1"9Sn Moessbauer spectroscopy  

International Nuclear Information System (INIS)

The ternary stannides RE_3Ru_4Sn_1_3 (RE = La, Ce, Pr, Nd) were obtained by arc-melting of the elements. The polycrystalline samples were characterized by powder X-ray diffraction. The structures of three compounds were refined from single-crystal diffractometer data: Yb_3Rh_4Sn_1_3 type, Pm anti 3n, a = 977.74(3) pm, wR2 = 0.0379, 280 F"2 values for La_3Ru_4Sn_1_3, a = 971.34(9) pm, wR2 = 0.0333, 274 F"2 values for Ce_3Ru_4Sn_1_3, a = 970.68(8) pm, wR2 = 0.0262, 272 F"2 values for Nd_3Ru_4Sn_1_3 with 13 variables per refinement. The structures consist of three-dimensional networks of condensed RuSn_6_/_2 trigonal prisms with the RE (CN 16) and Sn2 (CN 12) atoms in two different types of cavities of the networks. The two crystallographically independent tin sites have been resolved by "1"1"9Sn Moessbauer spectroscopy. Temperature-dependent magnetic susceptibility measurements of Ce_3Ru_4Sn_1_3 gave a reduced magnetic moment of 2.32 ?_B per Ce atom, indicating ...

2011-07-01

305

THE EFFECT OF INTERSTITIAL N ON GRAIN BOUNDARY COHESIVE STRENGTH IN Fe  

Energy Technology Data Exchange (ETDEWEB)

Increased nitrogen levels have been correlated with decreased ductility and elevated ductile-to-brittle transition temperature in pressure vessel steels [1]. However, the exact role played by nitrogen in the embrittlement of steels remains unclear. Miller and Burke have reported atom probe ion microscopy findings from neutron-irradiated low-alloy pressure vessel steel showing the presence of a 1 to 2 ruonolayer thick film of Mo, N, and C at prior austenitic grain boundaries (GB's) [2], suggesting a role for nitrogen as an intergranular embrittler. It is of interest for the development of mitigation strategies whether nitrogen must combine with other impurities to form nitride precipitates in order to exert an embrittling effect. Briant et al [1] have associated the embrittling effect of N in steels exclusively with intergranular nitride formation. This association suggests that high nitrogen levels may be acceptable if nitride precipitation at grain boundaries is suppressed. ...

2003-09-22

306

Synthesis of colloidal silver iron oxide nanoparticles--study of their optical and magnetic behavior.  

Science.gov (United States)

Silver iron oxide nanoparticles of fairly small size (average diameter approximately 1 nm) with narrow size distribution have been synthesized by the interaction of colloidal beta- Fe2O3 and silver nanoparticles. The surface morphology and size of these particles have been analyzed by using atomic force microscopy (AFM), field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). Their structural analysis has been carried out by employing x-ray diffraction (XRD), selected-area electron diffraction (SAED), optical and infrared (IR) spectroscopic techniques. The ageing of these particles exhibits the formation of self-assembly, possibly involving weak supramolecular interactions between Ag(I)O4 and Fe(III)O4 species. These particles display the onset of absorption in the near-infrared region and have higher absorption coefficient in the visible range compared to that of its precursors. Magnetic measurements reveal an interesting transition in their ...

2009-07-01

307

Synthesis of Ln_0_._6Sr_0_._4Co_0_._8Fe_0_._2O_3_-_#delta# powders through glycine-nitrate combustion process  

International Nuclear Information System (INIS)

Solid oxide fuel cell (SOFC) is a promising source of power generation in terms of conversion efficiency which is higher than the conventional one, as it is not limited by the Carnot efficiency. Theoretically, the SOFC have an efficiency of the order of 60-80 % but it is limited by the number of active side available for the reaction i.e. TPB (triple phase boundary) at the electrode-electrolyte interface which depends on the particle size of the materials employed during the fabrication of SOFC components (i.e. the method employed during the synthesis). Literally, there are several methods used in the syntheses of oxide materials such as conventional solid-state reaction, co-precipitation, hydrothermal rout, sol-gel and Glycine nitrate process (GNP) but among these GNP found to be effective over the other because of homogeneity, phase purity and smaller particle size of final product. In this work, the Nano-crystalline Ln_0_._6Sr_0_._4Co_0_._8Fe_0_._2O_3_-_#delta# (LSCF) cathode was ...

2010-12-01

308

Structure properties and magnetic susceptibility of diluted magnetic semiconductor Y_2_-_xHo_xO_3  

International Nuclear Information System (INIS)

The polycrystalline samples of Y_2_-_xHo_xO_3 (0.10#<=#x#<=#1.80) were synthesized by ceramic technology. The X-ray powder diffraction data were collected and the crystal structures were refined by the Rietveld method for the samples Y_2_-_xHo_xO_3 (x=0.00, 0.20, 0.40, 1.20, 1.80, 2.00). Holmium ions Ho"3"+ were randomly distributed over two cationic sites 8b and 24d in the space group Ia3 in all refined structures. Cation-anion-cation bonds important for superexchange interaction were determined. Magnetic susceptibility measurements were done by the Faraday method in the temperature range 290 to 620 K and a behaviour in accordance with the Curie-Weiss law was obtained. The molar Curie's constants linearly depend on concentration. The effective magnetic moments of Ho"3"+ ions were smaller than the free ion value. The Curie-Weiss paramagnetic temperatures indicated antiferromagnetic interaction. The gram ion susceptibilities confirmed the random distribution ...

1995-01-01

309

Spin-s tachyons and the propagation of tachyon waves. Part B  

International Nuclear Information System (INIS)

The propagation of bradyon and tachyon wave functions can be compared by considering them as cases of normal and anomalous dispersion and using the ideas of Brillouin which where developed in order to describe the propagation of light in a transparent medium near an adsorption line. It is found that if a wave packet, or pulse, is formed using a superposition of waves moving only in the positive x direction, including both positive energies, it will propagate superluminally for both bradyons and tachyons. If non-physical states, imaginary moments and energies, are included in the superposition, both types of waves will propagate subluminally and remain within the light cone. This last result has also been obtained by Fox, Kuper and Lipson and Strnad and Kodre for tachyons when they included imaginary energies in their superposition. However, these approaches allow the tachyon to be localizable in space and can lead to divergences in the wave packet. If all the ...

310

Results 2005 of the surveillance of the artificial radioactivity levels of aquatic ecosystems in the basin of Seine-Normandy. Riviere 2005; Resultats 2005 de la surveillance des niveaux de la radioactivite artificielle d'ecosystemes aquatiques appartenant au bassin Seine-Normandie. Riviere 2005  

Energy Technology Data Exchange (ETDEWEB)

Set up in 2004 by the A.C.R.O. the citizens network of radioecological surveillance, information and evaluation (R.I.V.I.E.R.E.) aims at making a follow-up of the radioactive contamination of the aquatic ecosystems on the scale of the Seine-Normandy pond: from Nogent-on-Seine to La Hague and from the Mont-Saint-Michel to the Treport. The peculiarity of this network, which also makes its strength is to associate strictly all those who wish to appropriate the knowledge of the radioactivity levels around to them. With R.I.V.I.E.R.E., the citizen is at the same moment an author and an actor of the surveillance of his environment as his information. An approach defended by the A.C.R.O. since about 20 years and which has no equivalent anywhere else. This project has four main objectives: to know the levels and the tendencies of the present radioactivity in the main aquatic ecosystems of the Seine-Normandy widened pond, and so feed a data base including more than 3000 ...

2005-07-01

311

Rainfall effect on single-vehicle crash severities using polychotomous response models.  

Science.gov (United States)

As part of the Wisconsin road weather safety initiative, the objective of this study is to assess the effects of rainfall on the severity of single-vehicle crashes on Wisconsin interstate highways utilizing polychotomous response models. Weather-related factors considered in this study include estimated rainfall intensity for 15 min prior to a crash occurrence, water film depth, temperature, wind speed/direction, stopping sight distance and deficiency of car-following distance at the crash moment. For locations with unknown weather information, data were interpolated using the inverse squared distance method. Non-weather factors such as road geometrics, traffic conditions, collision types, vehicle types, and driver and temporal attributes were also considered. Two types of polychotomous response models were compared: ordinal logistic and sequential logistic regressions. The sequential logistic regression was tested with forward and backward formats. Comparative ...

2009-08-14

312

Physiological responses of Pinus sylvestris to changing carbon dioxide and ozone concentrations  

Energy Technology Data Exchange (ETDEWEB)

The objective of this research is to study the effects of elevated ozone, carbon dioxide and their combination on ultrastructural, physiological and biochemical responses of Scots pine needles and how these effects are reflected to photosynthesis, carbohydrate and nutrient allocation and finally to shoot and root growth of trees. In addition the interactions of the studied trees and mycorrhizal fungi as well as insect herbivores are studied. The exposures have been running only for two growing periods and it seems necessary to continue the experiment over the third growing season in 1996. Since the analyses are partially incomplete, only preliminary conclusions are possible at the moment. The slightly increased shoot growth and needle width and increased amount of starch in chloroplasts point to the slight stimulating effect of elevated CO{sub 2} among the chamber treatments. Altogether the growth of the seedlings was best in the chamberless treatment indicating a ...

1996-12-31

313

Nucleon electromagnetic form factors from lattice QCD using 2+1 flavor domain wall fermions on fine lattices and chiral perturbation theory  

Science.gov (United States)

We present a high-statistics calculation of nucleon electromagnetic form factors in N{sub f}=2+1 lattice QCD using domain wall quarks on fine lattices, to attain a new level of precision in systematic and statistical errors. Our calculations use 32{sup 3}x64 lattices with lattice spacing a=0.084 fm for pion masses of 297, 355, and 403 MeV, and we perform an overdetermined analysis using on the order of 3600 to 7000 measurements to calculate nucleon electric and magnetic form factors up to Q{sup 2{approx_equal}}1.05 GeV{sup 2}. Results are shown to be consistent with those obtained using valence domain wall quarks with improved staggered sea quarks, and using coarse domain wall lattices. We determine the isovector Dirac radius r{sub 1}{sup v}, Pauli radius r{sub 2}{sup v} and anomalous magnetic moment {kappa}{sub v}. We also determine connected contributions to the corresponding isoscalar observables. We extrapolate these observables to the physical pion mass using ...

2010-02-01

314

Molecular orbitals of nucleons in nucleus-nucleus collisions  

International Nuclear Information System (INIS)

A formalism for the dynamical treatment of the molecular orbitals of valence nucleons in nucleus-nucleus collisions is developed with the use of the coupled-reaction-channel (CRC) method. The Coriolis coupling effects as well as the finite mass effects of the nucleon are taken into account in this model, of rotating molecular orbitals, RMO. First, the validity of the concept is examined from the viewpoint of the multi-step processes in a standard CRC calculation for systems containing two identical [core] nuclei. The calculations show strong CRC effects particularly in the case where the mixing of different l-parity orbitals - called hybridization in atomic physics - occurs. Then, the RMO representation for active nucleons is applied to the same systems and compared to the CRC results. Its validity is investigated with respect to the radial motion (adiabaticity) and the rotation of the molecular axis (radial and rotational coupling). Characteristic molecular orbitals of covalent ...

315

Measurement of the weak pion nucleon coupling constant, h1(pi), from backward pion photo-production near threshold on the proton  

Energy Technology Data Exchange (ETDEWEB)

The longest range weak pion-nucleon coupling constant, h1/n is important for nuclear parity violation. However, after considerable effort in the past two decades, its value is still poorly known largely due to many-body theoretical uncertainties. Prospects of a new measurement of h1/n in a theoretically clean process are presented. A measurement of the parity-violating asymmetry in pion photoproduction off the proton is related to h1/n in a low-energy theorem for the photon polarization asymmetry at threshold in the chiral limit. At present two completed experiments - photon circular polarization for 18F and the anapole moment of 133Cs - have been interpreted to give very different values of ...

2003-05-01

316

Magnetic susceptibility of Cesub(x)Lasub(1-x)B_6, Cesub(x)Eusub(1-x)B_6, Smsub(x)Lasub(1-x)B_6, and Smsub(x)Cesub(1-x)B_6 solid solutions  

International Nuclear Information System (INIS)

The magnetic susceptibility chi of Cesub(x)Lasub(1-x)B_6, Cesub(x)Eusub(1-x)B_6, Smsub(x)Lasub(1-x)B_6, and Smsub(x)Cesub(1-x)B_6 is investigated for temperatures of 80 to 1000 K. chi of Cesub(x)Lasub(1-x)B_6 and Cesub(x)Eusub(1-x)B_6 obeys the Curie-Weiss law. The composition dependence of effectiv magnetic moment #mu#sub(eff) exhibits an unusual behaviour. The value of #mu#sub(eff) per cerium ion abruptly decreases on substituting the cerium ions in CeB_6 by lanthanium ions. The values of the Weiss constants agree with the conclusions of the RKKY theory of indirect exchange by conduction electrons. The temperature dependence of chi of Smsub(x)Lasub(1-x)B_6 and Smsub(x)Cesub(1-x)B_6 do not obey the Curie-Weiss law. Both magnetic and X-ray data show that in Smsub(x)Lasub(1-x)B_6 and Smsub(x)Cesub(1-x)B_6 solid solutions the relative concentration of Sm"2"+ and Sm"3"+ ions changes with the change of composition. (author).

1980-11-01

317

Magnetic Resonance Perfusion Imaging in Malformations of Cortical Development  

International Nuclear Information System (INIS)

Background: Malformations of cortical development vary in neuronal maturity and level of functioning. Purpose: To characterize regional relative cerebral blood volume (rCBV) and difference in first moment transit time (TTfm) in polymicrogyria and cortical tubers using magnetic resonance (MR) perfusion imaging. Material and Methods: MR imaging and dynamic T2*-weighted MR perfusion imaging were performed in 13 patients with tuberous sclerosis complex, 10 with polymicrogyria, and 18 controls with developmental delay but no macroscopic brain abnormality. Regions of interest were placed in cortical tubers or polymicrogyric cortex and in the contralateral normal-appearing side in patients with malformations. In 'control' subjects, regions of interest were placed in the frontal and parietal lobes in both hemispheres. The rCBV and TTfm of the tuber/contralateral side (rCBVRTSC and TTFMTSC) as well as those of the polymicrogyria/contralateral side (rCBVRPMG and TTFMPMG) ...

2007-10-01

318

Heat transfer augmentation using a magnetic fluid under the influence of a line dipole  

Energy Technology Data Exchange (ETDEWEB)

Ferrofluids have promising potential for heat transfer applications, since advective transport in a ferrofluid can be readily controlled by using an external magnetic field. However, unlike conventional free or forced convection, ferrohydrodynamic convection is not yet well characterized. A full understanding of the relationship between an imposed magnetic field, the resulting ferrofluid flow, and the temperature distribution is a prerequisite for the proper design and implementation of applications involving thermomagnetic convection. The literature variously assumes constant magnetic fields, does not completely represent the variation in the imposed field, or its descriptions are inaccurate, since the fields do not comply with the Maxwell's equations of electromagnetism. We address this by simulating two-dimensional forced convection heat transfer in a channel with a ferrofluid that is under the influence of a two-dimensional magnetic field created by a line-source dipole. ...

2004-04-01

319

Heat transfer augmentation using a magnetic fluid under the influence of a line dipole  

International Nuclear Information System (INIS)

Ferrofluids have promising potential for heat transfer applications, since advective transport in a ferrofluid can be readily controlled by using an external magnetic field. However, unlike conventional free or forced convection, ferrohydrodynamic convection is not yet well characterized. A full understanding of the relationship between an imposed magnetic field, the resulting ferrofluid flow, and the temperature distribution is a prerequisite for the proper design and implementation of applications involving thermomagnetic convection. The literature variously assumes constant magnetic fields, does not completely represent the variation in the imposed field, or its descriptions are inaccurate, since the fields do not comply with the Maxwell's equations of electromagnetism. We address this by simulating two-dimensional forced convection heat transfer in a channel with a ferrofluid that is under the influence of a two-dimensional magnetic field created by a line-source dipole. Our ...

2004-04-01

320

General formulation of neutron noise for fast reactor systems  

Energy Technology Data Exchange (ETDEWEB)

A general space- and energy-dependent formalism is developed in order to analyze zero-power neutron noise experiments in fast reactor systems. A generalized dispersion equation is combined with theoretical expressions for the experimentally measured power spectral density and variance-to-mean ratio which makes it possible to express these quantities in terms of a double moment of the Laplace and Fourier transformed Green's function of a slowing-down operator rather than those of the full Boltzmann operator. Several spatial approximations are analyzed in the context of the general formalism. In each case, the power spectral density and variance-to-mean ratio are written in terms of an appropriate fast reactor dispersion law for the medium which can be calculated from the solution to a simple slowing-down equation. The resultant expression for the power spectral density are analyzed for various combinations of neutron migration descriptions, slowing-down ...

1982-01-01

321

Full scale heavily reinforced concrete beam-column joints of NPP structures-quality assurance and construction in the laboratory  

International Nuclear Information System (INIS)

Under the current design philosophy, reactor structures are to be designed to withstand large inelastic deformation caused by strong and severe ground motion. The design of the main structural elements and their connections are to be such that they always fail in ductile mode. This will ensure large energy absorption capacity of the structures under seismic excitation and avoid sudden and brittle failure of the structure. Over the years, a number of experimental investigations have been carried out on RC beam- column joints to study their behaviour and strength. However, these studies mostly pertain to small scale joints of moment resisting frame of residential buildings and commercial complexes. Information on full scale joints existing in NPP structures are scanty. Therefore, experimental programme was planned in the laboratory to construct identical large sized joints with the same reinforcement percentage and detail as that of the existing joints in NPP ...

2003-02-01

322

Frontiers of Nuclear Astrophysics  

International Nuclear Information System (INIS)

The main goals of nuclear astrophysics have been to probe the interiors of stars, stellar explosions, the early moments of cosmic expansion, and the formation and evolution of galaxies and cosmic structure by measurement and application of the relevant nuclear physics. The approach to these goals have generally been from three directions: 1) Careful measurements of the relevant nuclear reactions; 2) Detailed computer models of the relevant astrophysical environments; and 3) Observations of the relevant terrestrial and extra-terrestrial atomic and isotopic abundances. These approaches provide not only insight into the formation and evolution of the elements, but are also pillars upon which a variety of cosmological models as well as models for physics beyond the standard model of particle physics can stand or fall. At present there is a very exciting frontier on all three of these approaches. The development and applications of radioactive-ion-beam and ...

2008-06-01

323

Exposure of Finnish population to solar UV radiation and consequent carcinogenic effects  

Energy Technology Data Exchange (ETDEWEB)

Depletion of stratospheric ozone increases irradiance of terrestrial ultraviolet (UV) radiation at short wavelengths, which may be harmful to the human health. To understand quantitatively the risks caused by increasing UV radiation to the Finnish population, the actual UV exposure of the population has to be assessed. It was shown that the snow reflection increases the UV exposure to the face and eyes particularly in the northern Finland. In 1993 exceptionally low ozone levels persisted up to the end of May, which resulted in a theoretical increase in the annual UV dose ranging from 8 % to 13 % in Finland. The maximal increase in the measured erythemally effective dose rate was 34 % on 23 April, when compared with the theoretical normal value. During this study exposure models have been developed. The models have been combined them with Green`s radiation transfer model to estimate annual facial UV doses received by different groups of Finnish population. Also, an updated estimate for ...

1996-12-31

324

Elastic flexural properties of multistranded stainless steel versus conventional nickel titanium archwires.  

Science.gov (United States)

Based on a recent investigation that modeled the elastic properties (ie, strength, stiffness and range) of multistranded wires made from linearly elastic materials, three-stranded (triple) and six-stranded coaxial (coax) stainless steel (SS) wires were compared to single-stranded (single) SS and conventional nickel titanium (NiTi) leveling wires. To measure Young's modulus of elasticity (E), flexural tests were performed with an Instron mechanical testing machine in a three-point bending arrangement having a span length of 8.9 mm or 12.5 mm. A strong correlation between wire stiffness and the area moment of inertia demonstrated that strand interaction was negligible at low activations and that E = 199 GPa was constant even for the heavily drawn coax strands. Using the Instron with an extensometer, the 0.1% yield strengths (sigma(YS)) of the single SS wires and the straight inner strands within the coax wires were tested. The ratio of the sigma(YS) to the ultimate ...

2002-08-01

325

Effective Lagrangian description of Higgs mediated flavor violating electromagnetic transitions: Implications on lepton flavor violation  

International Nuclear Information System (INIS)

Higgs mediated flavor violating electromagnetic interactions, induced at the one-loop level by a nondiagonal Hf_if_j vertex, with f_i and f_j charged leptons or quarks, are studied within the context of a completely general effective Yukawa sector that comprises SU_L(2)xU_Y(1)-invariant operators of up to dimension-six. Exact formulae for the one-loop #gamma#f_if_j and #gamma##gamma#f_if_j couplings are presented and their related processes used to study the phenomena of Higgs mediated lepton flavor violation. The experimental limit on the #mu##->#e#gamma# decay is used to derive a bound on the branching ratio of the #mu##->#e#gamma##gamma# transition, which is 6 orders of magnitude stronger than the current experimental limit. Previous results on the #tau##->##mu##gamma# and #tau##->##mu##gamma##gamma# decays are reproduced. The possibility of detecting signals of lepton flavor violation at #gamma##gamma# colliders is explored through the #gamma##gamma##->#l_il_j ...

2009-05-01

326

Direct observation of ordered orbital of YTiO{sub 3} by the X-ray magnetic diffraction technique  

Energy Technology Data Exchange (ETDEWEB)

X-ray magnetic diffraction (XMD) technique was applied to an orbital ordering compound of ferromagnetic YTiO{sub 3} for the first time. The orbital-magnetic form factor {mu} {sub L}(k) and the spin-magnetic form factor {mu} {sub S}(k) were independently measured by utilizing the LS separation ability of the XMD. The {mu} {sub L}(k) was measured for ten reciprocal-lattice points. No significant values of the {mu} {sub L}(k) were observed for most of the reciprocal-lattice points within the estimated statistical errors, which suggested quenching of the orbital moment. The {mu} {sub S}(k) was measured for 22 reciprocal-lattice points. Fourier synthesis of the {mu} {sub S}(k) gave the spin density distribution m {sub S}(r) in the real space. The obtained m {sub S}(r) map shows the characteristic feature of the electron distribution of 3d electron in the t{sub 2g} state of a Ti atom coordinated by O{sup 2-} ions, in which the electrons are distributed away from the ...

2005-08-15

327

Development of Intelligent Setting System for Fracture Based on X-Ray Image  

Energy Technology Data Exchange (ETDEWEB)

In order to achieve micro-wound, intelligence and high efficiency for fracture setting, intelligent setting system for fracture is proposed in accordance with biomechanics and fracture therapy theory. In the comprehensive medical system based on C-shape-arm X-machine, image processing and analysis is the core, programmable logical controller and stepping motor are important driving parts controlling mechanical parts. Six degree of freedom dynamics sensor ensures to control accurately force and moment. On the foundation of analyzing X-ray image peculiarities, method of processing and analysis is put forward, combining time domain with frequency domain. After mining domain knowledge in depth, setting actions is quantized into three non-continuous steps and is parameterized into two angles and one distance aiming at femoral-neck fracture. Objective features are extracted by virtue of three power polymerization curved surface fitting. Master-slave reference frame is ...

2006-10-15

328

Development and application of a third order scheme of finite differences centered in mesh; Desarrollo y aplicacion de un esquema de tercer orden de diferencias finitas centradas en malla  

Energy Technology Data Exchange (ETDEWEB)

In this work the development of a third order scheme of finite differences centered in mesh is presented and it is applied in the numerical solution of those diffusion equations in multi groups in stationary state and X Y geometry. Originally this scheme was developed by Hennart and del Valle for the monoenergetic diffusion equation with a well-known source and they show that the one scheme is of third order when comparing the numerical solution with the analytical solution of a model problem using several mesh refinements and boundary conditions. The scheme by them developed it also introduces the application of numeric quadratures to evaluate the rigidity matrices and of mass that its appear when making use of the finite elements method of Galerkin. One of the used quadratures is the open quadrature of 4 points, no-standard, of Newton-Cotes to evaluate in approximate form the elements of the rigidity matrices. The other quadrature is that of 3 points of Radau that it is used to ...

2003-07-01

329

Building a Construction Curriculum for Your School District  

Science.gov (United States)

Embracing the notion of going green, an affluent school district in Pennsylvania spent $83 million as part of the high school's renovation and expansion project. The three-level addition is now equipped with self-dimming lights, energy-efficient windows, a rooftop solar water heater, and a geothermal cooling and heating system. As a bonus for going green, the school district received a $250,000 grant from the Pennsylvania Department of Environmental Protection. The district used that money to create an information center in the lobby of the building where a touch-screen computer provides students, staff, and visitors with data related to the operation of the school's energy-efficient water and electrical systems. The system will graphically depict utility use over the course of a year. The monitoring system and touch-screen computer can turn this school into a living lab, with science, math, and economics teachers using the data as teaching tools within classrooms. Teachers can also ...

2010-06-01

330

Adsorption of benzene on graphitized thermal carbon black: reduction of the quadrupole moment in the adsorbed phase.  

Science.gov (United States)

The performance of intermolecular potential models on the adsorption of benzene on graphitized thermal carbon black at various temperatures is investigated. Two models contain only dispersive sites, whereas the other two models account explicitly for the dispersive and electrostatic sites. Using numerous data in the literature on benzene adsorption on graphitized thermal carbon black at various temperatures, we have found that the effect of surface mediation on interaction between adsorbed benzene molecules must be accounted for to describe correctly the adsorption isotherm as well as the isosteric heat. Among the two models with partial charges tested, the WSKS model of Wick et al. that has only six dispersive sites and three discrete partial charges is better than the very expensive all-atom model of Jorgensen and Severance. Adsorbed benzene molecules on graphitized thermal carbon black have a complex orientation with respect to distance from the surface and also with respect to ...

2006-01-31

331

Adsorption and dissociation of water on the (0001) surface of double hexagonal close packed americium  

International Nuclear Information System (INIS)

Ab initio total energy calculations within the framework of density functional theory have been performed for water molecule adsorption on the (0001) surface of double hexagonal packed americium using a full-potential all-electron linearized augmented plane wave plus local orbitals method (FP-L/APW+lo). Subsequent partial dissociation (OH+H) and complete dissociation (H+O+H) of the water molecule have been examined. The completely dissociated H+O+H configuration exhibit the strongest binding with the surface (3.35 eV), followed by partially dissociated species OH+H (2.23 eV), with all molecular H_2O configurations showing weak physisorption (0.366 eV). For molecular adsorptions, the flat lying orientation of the water molecule if found to be more favorable for majority of the cases. In the case of partial dissociation (OH+H), the vertical orientation of OH molecule with O facing the surface adsorbed at a h3 adsorption site and the H atom adsorbed at another neighboring h3 site is found ...

2009-06-01

332

A model for the calculation of vent clearing transients in pressure suppression systems  

International Nuclear Information System (INIS)

For the layout of a pressure suppression system of a light water cooled reactor (boiling water reactor) it is important to know the time dependent behavior of the vent clearing transient after a loss-of-coolant accident for two main reasons: time of the end of the vent clearing transient influences strongly the pressure and temperature maxima in the drywell and wetwell. Time-dependent behavior of the vent clearing transient influences pressure loads in the condensation pool of the wetwell and therefore pressure induced stresses to the structure. The time-dependent behavior of the water masses in the vent pipes and wetwell are described by the basic equations for a nonstationary incompressible friction flow: momentum equation, continuity equation and a correlation for the variation of the state of the gas volume in the wetwell above the water level. After many algebraic operations and integrations along the flow path, a single ordinary nonlinear differential equation for the variations ...

1975-09-01

333

A density functional study of atomic hydrogen and oxygen chemisorption on the relaxed (0001) surface of double hexagonal close packed americium  

International Nuclear Information System (INIS)

Ab initio total energy calculations within the framework of density functional theory have been performed for atomic hydrogen and oxygen chemisorption on the (0001) surface of double hexagonal packed (dhcp) americium using a full-potential all-electron linearized augmented plane wave plus local orbitals method. Chemisorption energies were optimized with respect to the distance of the adatom from the relaxed surface for three adsorption sites, namely top, bridge, and hollow hcp sites, the ad-layer structure corresponding to the coverage of a 0.25 monolayer in all cases. Chemisorption energies were computed at the scalar-relativistic level (no spin-orbit coupling NSOC) and at the fully relativistic level (with spin-orbit coupling SOC). The two-fold bridge adsorption site was found to be the most stable site for O at both the NSOC and SOC theoretical levels with chemisorption energies of 8.204 eV and 8.368 eV respectively, while the three-fold hollow hcp adsorption site was found to be ...

2008-02-01

334

A High-Frequency Secondary Event During the 2004 M6.0 Parkfield Earthquake  

Science.gov (United States)

We present an image of the rupture propagation of the 2004 M6.0 Parkfield earthquake using records from a dense network of local strong motion stations. We back-propagate high-frequency waveforms in 3D with a method, similar to reverse time migration, to obtain an estimate of the distribution of radiated high-frequency seismic energy in space and time. The image is forced to be coherent at the known hypocenter location and the quake origin time by applying small static time shifts obtained using waveform cross-correlation. We observe that the Parkfield earthquake radiated a distinct secondary high-frequency phase, which is located about 12.5~km northwest of the hypocenter with an onset of seismic radiation about 5~s after the rupture initiation. The time history of the back-projection suggests a rupture velocity of 2.5~km/s between hypocenter and subevent. The back-projection result is confirmed by inversion of picked arrival times of the secondary event clearly visible at some of the ...

2007-12-01

335

Upper Paleozoic petroleum system, Ordos Basin, China  

Energy Technology Data Exchange (ETDEWEB)

The Ordos Basin is a typical lapped basin, including three sequences of strata: early Paleozoic, late Paleozoic and Mesozoic, with a total thickness of 4000-6000m. Impermeable sealing beds are well developed at the top and base of the upper Paleozoic sequence, separating it from the Mesozoic and the lower Paleozoic strata to form an independent petroleum system. In this petroleum system, the source rocks are widely distributed coals and dark mudstones occurring in the Carboniferous-lower Permian coal measures, with a thickness of 10-15 and 40-60m, respectively. The reservoirs are mainly early Permian tight sandstones, mostly with a porosity of 4-8% and a permeability of 0.1-1.0x10{sup -3}{mu}m{sup 2}. The regional cap rock is a 100-150m thick mudstone in the upper Permian strata. The structural framework of the basin is a huge asymmetric syncline, dipping gently toward the east and north, and steeply toward the south and west. Well data show that gas-saturated, gas-water transition and ...

2005-09-01

336

RADIAL DISTRIBUTION OF STARS, GAS AND DUST IN SINGS GALAXIES. I. SURFACE PHOTOMETRY AND MORPHOLOGY  

International Nuclear Information System (INIS)

We present ultraviolet through far-infrared (FIR) surface brightness profiles for the 75 galaxies in the Spitzer Infrared Nearby Galaxies Survey (SINGS). The imagery used to measure the profiles includes Galaxy Evolution Explorer UV data, optical images from Kitt Peak National Observatory, Cerro Tololo Inter-American Observatory, and Sloan Digital Sky Survey, near-IR data from Two Micron All Sky Survey, and mid- and FIR images from Spitzer. Along with the radial profiles, we also provide multi-wavelength asymptotic magnitudes and several nonparametric indicators of galaxy morphology: the concentration index (C 42), the asymmetry (A), the Gini coefficient (G), and the normalized second-order moment of the brightest 20% of the galaxy's flux (M-bar20). In this paper, the first of a series, we describe the technical aspects regarding the surface photometry, and present a basic analysis of the global and structural properties of the SINGS galaxies at different ...

2009-10-01

337

Proposal of procedures to prevent errors in radiotherapy based in learned lessons of accidental expositions; Proposta de procedimentos para evitar erros em radioterapia baseados em licoes aprendidas de exposicoes acidentais  

Energy Technology Data Exchange (ETDEWEB)

In order to consider some procedures to prevent errors in radiotherapy based in learned lessons of accidental expositions and in accordance with information contained in international reports elaborated by International Atomic Energy Agency (IAEA) and of the data base availability by the European group Radiation Oncology Safety Information System (ROSIS) on the events, a research of the occurred errors was performed. For the evaluation of the incidents a data base based in the ROSIS and added plus a parameter was created 'type of error'. All the stored data make possible the evaluation of the 839 incidents in terms of frequency of the type of error, the process of detention, the number of reached patients and the degree of severity. Of the 50 types of found errors, the type of error more frequently was 'incorrect treatment coordinate', confirmed with the data of literature and representing 28,96 por cent of the total of the incidents. The results ...

2007-07-01

338

Phase formation, crystal structures and magnetic properties of perovskite-type phases in the system La2Co1+z(MgxTi1-x)1-zO6  

International Nuclear Information System (INIS)

Perovskite-type cobaltates in the system La2Co1+z(MgxTi1-x)1-zO6 were studied for z=0?x?0.6 and 0?xoC. The space group symmetry of the structure changes from P21/n via Pbnm to R3-bar c with both increasing Mg content and increasing Co content. The La2Co(MgxTi1-x)O6 (z=0) compounds show anti-ferromagnetic couplings of the magnetic moments for the Co below 15 K for x=0, 0.1 and 0.2. XANES spectra show for the compositions 0?x?0.5 a linear decrease in the L3/(L3+L2) Co-L2,3 edge branching ratio with x, in agreement with a decrease of the average Co ion spin-state, from a high-spin to a lower-spin-state, with decreasing nominal Co2+ ion content. -- Graphical abstract: XRPD patterns for perovskite compounds along the lines La2Co(MgxTi1-x)O6 and La2Co1+z(Mg0.5Ti0.5)1-zO6. Display Omitted Research Highlights: ?Tuning of the oxidation state of Co in the perovskite system La2Co1+z(Mtem La2Co1+z(MgxTi1-x)1-zO6, z=0?x?0.6 and 0?x2Co1+z(MgxTi1-x)1-zO6, z=0?x?0.6 and ...

2011-01-01

339

Nonphotochemical Hole-Burning Imaging Studies of in vitro Carcinoma and Normal Cells Utilizing a Mitochondrial Specific Dye  

Energy Technology Data Exchange (ETDEWEB)

Low temperature Nonphotochemical Hole Burning (NPHB) Spectroscopy of the dye rhodamine 800 (MF680) was applied for the purpose of discerning differences between cultured normal and carcinoma ovarian surface epithelial (OSE) cells. Both the cell lines were developed and characterized at the Mayo Clinic (Rochester, MN), with the normal cell line having been transfected with a strain of temperature sensitive Simian Virus 40 Large T Antigen (SV40) for the purpose of extending the life of the cell culture without inducing permanent changes in the characteristics of the cell line. The cationic lipophilic fluorophore rhodamine 800 preferentially locates in in situ mitochondria due to the high lipid composition of mitochondria and the generation of a large negative membrane potential (relative to the cellular cytoplasm) for oxidative phosphorylation. Results presented for NPHB of MF680 located in the cells show significant differences between the two cell lines. The results are interpreted on ...

2002-06-27

340

Nonphotochemical Hole-Burning Imaging Studies of In Vitro Carcinoma and Normal Cells Utilizing a Mitochondrial Specific Dye  

Energy Technology Data Exchange (ETDEWEB)

Low temperature Nonphotochemical Hole Burning (NPHB) Spectroscopy of the dye rhodamine 800 (MF680) was applied for the purpose of discerning differences between cultured normal and carcinoma ovarian surface epithelial (OSE) cells. Both the cell lines were developed and characterized at the Mayo Clinic (Rochester, MN), with the normal cell line having been transfected with a strain of temperature sensitive Simian Virus 40 Large T Antigen (SV40) for the purpose of extending the life of the cell culture without inducing permanent changes in the characteristics of the cell line. The cationic lipophilic fluorophore rhodamine 800 preferentially locates in in situ mitochondria due to the high lipid composition of mitochondria and the generation of a large negative membrane potential (relative to the cellular cytoplasm) for oxidative phosphorylation. Results presented for NPHB of MF680 located in the cells show significant differences between the two cell lines. The results are interpreted on ...

2002-08-01

341

Multi-scale modeling of fiber and fabric reinforced cement based composites  

Science.gov (United States)

With an increased use of fiber reinforced concrete in structural applications, proper characterization techniques and development of design guides are needed. This dissertation presents a multi-scale modeling approach for fiber and fabric reinforced cement-based composites. A micromechanics-based model of the yarn pullout mechanism due to the failure of the interfacial zone is presented. The effect of mechanical anchorage of transverse yarns is simulated using nonlinear spring elements. The yarn pullout mechanism was used in a meso-scale modeling approach to simulate the yarn bridging force in the crack evolution process. The tensile stress-strain response of a tension specimen that experiences distributed cracking can be simulated using a generalized finite difference approach. The stiffness degradation, tension stiffening, crack spacing evolution, and crack width characteristics of cement composites can be derived using matrix, interface and fiber properties. The theoretical models ...

2008-01-01

342

Evaluation method for grate combustion (EMGC); Utvaerderingsmetod foer eldning i rostpannor  

Energy Technology Data Exchange (ETDEWEB)

The aim with this project sponsored by Energimyndigheten is to develop a method for calculations of grate boilers fueled by bark. This report describes this project, 'Evaluation Method for Grate Combustion' (EMGC). CFD codes is an engineering tool applicable in the area of the over-grate section called the furnace. This part of the boiler is easy to model for an experienced CFD code user and the results are usually quite satisfactory for evaluating the combustion process in general. Various gas phases reactions and related combustion processes over the burning bed can be simulated including air staging, fuel staging and SNCR. However the simulation needs information of amount and properties of the burning bed products, entering the furnace. The simulation of the in-furnace processes without this information is often just a numerical speculation. A predictive mathematical model based on physical and chemical data for the grate and fuel bed would solve this problem. ...

2000-04-01

343

Energy value as a factor of agroforestry wood species selectivity in Akinyele and Ido local government areas of Oyo State, Nigeria  

Energy Technology Data Exchange (ETDEWEB)

Wood usage for cooking and heating is still very relevant in most developing countries especially those of sub-Saharan Africa and many parts of Asia. Therefore, sustainable means of generating it for this and other purposes are necessary bearing in mind the influence of indigenous knowledge/users' perspective on any production method regarding success and sustenance. In conformity with this view, questionnaires were administered on 240 respondents in 8 rural communities of Akinyele and Ido Local Government Areas (LGAs) of Oyo State, Nigeria, to elicit information on species that can be used as fuelwood, preferred by the respondents for incorporation into and/or retention in agroforestry plots, out of which 179 (i.e. 75% of the total number of questionnaires administered) were successfully retrieved for statistical analyses. Twelve woody species namely: Annona senegalensis, Anogeissus leiocarpus, Bridelia ferruginea, Daniellia oliveri, Detarium microcarpum, Gardenia ternifolia, ...

2009-10-15

344

Comprehensive Approaches to Multiphase Flows in Geophysics - Application to nonisothermal, nonhomogenous, unsteady, large-scale, turbulent dusty clouds I. Hydrodynamic and Thermodynamic RANS and LES Models  

Energy Technology Data Exchange (ETDEWEB)

The objective of this manuscript is to fully derive a geophysical multiphase model able to ''accommodate'' different multiphase turbulence approaches; viz., the Reynolds Averaged Navier-Stokes (RANS), the Large Eddy Simulation (LES), or hybrid RANSLES. This manuscript is the first part of a larger geophysical multiphase project--lead by LANL--that aims to develop comprehensive modeling tools for large-scale, atmospheric, transient-buoyancy dusty jets and plume (e.g., plinian clouds, nuclear ''mushrooms'', ''supercell'' forest fire plumes) and for boundary-dominated geophysical multiphase gravity currents (e.g., dusty surges, diluted pyroclastic flows, dusty gravity currents in street canyons). LES is a partially deterministic approach constructed on either a spatial- or a temporal-separation between the large and small scales of the flow, whereas RANS is an entirely probabilistic ...

2005-09-05

345

Unsteady aerodynamic forces of a flapping wing.  

Science.gov (United States)

The unsteady aerodynamic forces of a model fruit fly wing in flapping motion were investigated by numerically solving the Navier-Stokes equations. The flapping motion consisted of translation and rotation [the translation velocity (u(t)) varied according to the simple harmonic function (SHF), and the rotation was confined to a short period around stroke reversal]. First, it was shown that for a wing of given geometry with u(t) varying as the SHF, the aerodynamic force coefficients depended only on five non-dimensional parameters, i.e. Reynolds number (Re), stroke amplitude (Phi), mid-stroke angle of attack (alpha(m)), non-dimensional duration of wing rotation (Delta tau(r)) and rotation timing [the mean translation velocity at radius of the second moment of wing area (U), the mean chord length (c) and c/U were used as reference velocity, length and time, respectively]. Next, the force coefficients were investigated for a case in which typical values of these ...

2004-03-01

346

Status of steam generators in Spain  

International Nuclear Information System (INIS)

There are a total of nine operational nuclear plants in Spain totalling 7.350 MWe. These units produced 54.265 x 106 KWh in 1990, 36% of the total generation in Spain. Seven of these plants are of the PWR type. The first plant in operation was Jose Cabrera (ZORITA) in 1968, one loop Westinghouse plant with a model 24 Steam Generator. Due to the design margin and careful operation of the Steam Generator of this plant its performance have been very good, with only 5% tubes plugged after 23 years of operation. This is one of the few units in the world that remains in phosphate chemistry. During the period 1981-1985 a total of four units, two in Almaraz and two in Asco entered in operation. These three loop s Westinghouse units use model D-3 preheater Steam Generators. The poor design and manufacture of the Steam Generators of these units have caused a large number of problems: mechanical (Preheater and AVB's vibration), denting, and primary and secondary stress corrosion cracking. As a ...

1991-09-16

347

Model to simulate the interaction between boron carbide and steam or air at high temperature  

Energy Technology Data Exchange (ETDEWEB)

The oxidation of boron carbide in steam or air was recently extensively studied especially in Forschungszentrum Karlsruhe, Institut fuer Materialforschung. An important data set is available for the interaction modelling. An oxygen diffusion model through the superficial liquid boron oxide formed on the boron carbide external surface associated to a superficial reaction between the liquid boron oxide and steam is proposed to simulate the experimental kinetics from BOX rig and thermogravimetric tests on the interaction between steam and boron carbide at a temperature range 800 C to 1400 C. The oxygen diffusion model will be also useful to simulate interaction between boron carbide and Ar+O2 (air simulation) atmosphere when the steam pressure becomes zero. From the analysis of BOX rig experimental kinetics of non-condensable (H2, CO2, CO and CH4) gases we propose an oxygen diffusion model through the liquid boron oxide and a ''steam/liquid boron ...

2005-03-01

348

Detection of high-frequency radiation sources during the 2004 Parkfield earthquake by a matched filter analysis  

Science.gov (United States)

Introduction Uchide and Ide [SSA Spring Meeting, 2009] proposed a new framework for studying the scaling and overall nature of earthquake rupture growth in terms of cumulative moment functions. For better understanding of rupture growth processes, spatiotemporally local processes are also important. The nature of high-frequency (HF) radiation has been investigated for some time, but its role in the earthquake rupture process is still unclear. A wavelet analysis reveals that the HF radiation (e.g., 4 - 32 Hz) of the 2004 Parkfield earthquake is peaky, which implies that the sources of the HF radiation are isolated in space and time. We experiment with applying a matched filter analysis using small template events occurring near the target event rupture area to test whether it can reveal the HF radiation sources for a regular large earthquake. Method We design a matched filter for multiple components and stations. Shelly et al. [2007] attempted identifying ...

2009-12-01

349

Carbomolybdates(III): On Pr{sub 2}[Mo{sub 2}C{sub 3}] and structural relations to Er{sub 2}Mo{sub 2}C{sub 3}; Carbomolybdate(III): Zur Kenntnis von Pr{sub 2}[Mo{sub 2}C{sub 3}] sowie Strukturbeziehungen zu Er{sub 2}Mo{sub 2}C{sub 3}  

Energy Technology Data Exchange (ETDEWEB)

Pr{sub 2}[Mo{sub 2}C{sub 3}] was obtained by arc melting of the elements followed by annealing at 1500 C in arc welded and sealed Mo-ampoules. The compound was characterised by chemical analyses, X-ray diffraction and metallography. The crystal structure (monoclinic, P2{sub 1}/c, Z = 4, a = 597.99(10) pm, b = 665.15(11) pm, c = 1185.60(19) pm and {beta} = 111.631(5) ) represents a new structure type containing a three dimensional polyanion {sub {infinity}}{sup 3}[(Mo{sub 2}C{sub 3}){sup 6-}] with Molybdenum(III) in a distorted tetrahedral coordination by carbo-ligands. Tetrameric building-blocks, Mo{sub 4}C{sub 10}, of edge sharing MoC{sub 4}-tetrahedra are arranged to form layers running parallel to (100). The layers are interconnected along [100] by sharing common apices of the MoC{sub 4} tetrahedra. The coordination polyhedra around praseodymium represent distorted (PrC{sub 5})-arrangements (mono capped tetrahedra and square pyramids). The metal atoms together form a distorted motif ...

2004-11-01

350

Final Scientific EFNUDAT Workshop  

ScienceCinema

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351

40th Anniversary of the First Proton-Proton Collisions in the CERN Intersecting Storage Rings (ISR)  

ScienceCinema

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352

Final Scientific EFNUDAT Workshop  

ScienceCinema

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353

Science at the Theater: Hot Technology, Cool Science  

ScienceCinema

...and welcome to ...lab also known as berkeley lab my name is jeff miller and ...and a public affairs i'd like to ? ...but space is science center and ...berkeley albany high school science department and berkeley high school science department and oakland high school science ...be a q. and ...here please use and because we wanna make sure that your questions are here ...heard of also for the latest developments on science and technology ...guy we're going to be any more and more new features i hope ...and change ...thank you ? much and thank you for coming on the welcome to my world of and mayotte science journalist and what i've done for the last almost thirty years ...people about things about which there passionate and national religion tonight and ...people to explain the science and and i asking the question so what ...and ...worldwide and what it does best ? uh ...bench science and turn it into reality what do you scientists and ...uh they take scientific theory and they turn ...